Hemodynamic parameters to guide fluid therapy

A prospective randomized comparison of a pulse-contour analysis monitor versus a non-invasive bioreactance monitor in a stroke-volume based goal-directed fluid resuscitation protocol in brain-dead organ donors

BACKGROUND

Brain-dead (BD) organ donors are frequently hypotensive and hypovolemic requiring fluid resuscitation. We previously published our four-hour stoke volume (SV)-based fluid resuscitation protocol that expeditiously corrected the fluid deficit and significantly decreased time on vasopressors. The SV was measured by pulse-contour analysis (PCA).

OBJECTIVE

To determine if the measurement of stroke volume by bioreactance (BR) was equivalent to PCA in a goal-directed fluid resuscitation protocol in BD donors.

METHODS

We performed a prospective randomized trial of fluid resuscitation in BD donors comparing the two monitors.

RESULTS

In 169 deceased donors there were 1481 comparative measurements of SV. The correlation coefficient was 0.32. A Bland Altman analysis revealed a minimal bias (-1.8 ml) but large limits of agreement (±62.9 ml) and a percentage error of 80.5 %. A 10 % SV increase with a 500 ml fluid bolus had conflicting results between the monitors in 31.3 % of 1309 measurements. As a reference standard, the Fick method of measuring SV was used 49 times with simultaneous measurements of PCA-SV and BR-SV. The mean Fick SV (96.0 ± 30.6 ml) was significantly greater than BR (79.4 ± 18.1 ml; p<.01) and the PCA (77.2 ± 22.5 ml; p<.01). The mean SV differences for Fick-BR (16.6 ± 27.2, 95 % CI 8.78-24.42) and Fick-PCA (18.7 ± 29.0, 95 % CI 10.42-27.08) were not significantly different (p=.57).

CONCLUSION

Although this study demonstrated inaccuracies, imprecision, and disagreement between BR and PCA SV measurements, there was equipoise in clinical outcomes when used with our fluid resuscitation protocol, as previously published.

Prognostic Value of Noninvasive Central Blood Pressure and Arterial Stiffness in Hemodynamic Shock

OBJECTIVES

Elevated central blood pressure (BP) and arterial stiffness are risk factors for cardiovascular mortality. However, their prognostic value in patients with hemodynamic shock has not been studied broadly. Evolved BP monitoring devices enable the noninvasive assessment of central BP and arterial stiffness. The objective of this study was to evaluate the prognostic value of central BP and arterial stiffness measurements, delivered by 2 noninvasive devices, in patients with septic or cardiogenic shock admitted to the intensive care unit.

DESIGN

This is a monocenter, prospective, cohort study.

SETTING

This study was conducted in a tertiary university hospital.

PARTICIPANTS

We enrolled 57 patients who were admitted to the intensive care unit with septic or cardiogenic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Central BP and arterial stiffness indices like pulse wave velocity (PWV) and Aix were recorded with a Mobil-o-Graph 24h PWA and SphygmoCor XCEL. Age, catecholamine dosage, resuscitation incidence before inclusion, C-reactive protein, leukocytes, and creatinine were recorded as possible confounders. With regard to the confounders, central systolic BP measured in the first 24 hours, was predictive of 6-month mortality (odds ratio, 0.9; p < 0.05). Aix, recorded by Mobil-o-Graph 24h PWA, was associated with death in the first 14 days (odds ratio, 1.11; p = 0.03). An increased PWV was not associated with adverse outcomes.

CONCLUSIONS

Low central BP and increased Aix were linked to a higher mortality in shock patients. PWV had no prognostic value.

Hemodynamic effects of slower versus faster intravenous fluid bolus rates in critically ill patients: An observational study

PURPOSE

We compared the immediate and sustained effects of 500 mL of crystalloid administered at slow (333 mL/h) versus fast rates (999 mL/h) on mean arterial pressure (MAP) in critically ill patients.

MATERIALS AND METHODS

Hemodynamic variables were collected immediately before and every 30 min up to 60 min after the end of the infusion. The primary outcome was the adjusted difference in MAP.

RESULTS

We included 146 patients (slow rate: 71, fast rate: 75). One hour after the end of the infusion, there was no difference in the overall mean marginal effect on MAP between the groups [1.9 mmHg (95 % CI: -1.5 to 5.3 mmHg), p = 0.27] or on the perfusion parameters. Similarly, no difference was found in the immediate effect after 90 min [overall marginal effect: 1.1 mmHg (95 % CI: -2.3 to 4.6 mmHg); p = 0.52]. In patients with cardiac output (CO) monitoring, there was an increase in CO in the fast rate group (overall mean marginal effect: 1.78 L/min (95 % CI: 0.08 to 3.48 L/min); p = 0.04).

CONCLUSION

In critically ill patients, crystalloid infusion at both fast and slow rates did not lead to immediate or sustained differences in MAP. However, fast infusion may result in a greater increase in CO.

Non-Invasive Cardiac Output Monitoring with Electrical Cardiometry During Laparoscopic Cholecystectomy Surgery, a Cross-Sectional Study

Background: Increased intra-abdominal pressure (IAP), autonomic reactions, and anesthetics all contribute to hemodynamic alterations during laparoscopic cholecystectomy. This study's objectives are to measure noninvasively the intraoperative individual responses in cardiac and systemic hemodynamics, focusing on cardiac output (CO. L/min), stroke volume (SV, mL/min), systemic vascular resistance (SVR, dyn.s.cm-5), and noninvasive mean arterial blood pressure (MABP, mmHg) during and after peritoneal insufflation (cmH2O). The secondary objective was to evaluate the utility of EC as an adjunct to standard monitoring and to assess the individual differences. Methods: The CO and associated parameters were continuously and noninvasively monitored with the electrical cardiometry (EC, ICON, Osypka, Berlin Germany). Results: Seventy-three patients showed that when the IAP increased to 13 [IQR: 13-14] cmH2O, there was an overall percentage decrease in CO (-11.29%), MABP (-9.31%), and SVR (-23.16%) compared to pre induction with minimal changes in heart rate (HR). Individual variation and extreme reactions among certain patients were noted, with CO falling by -47.14% and MABP by -61.59, respectively, which can have major repercussions. Conclusions: The EC enabled real-time, non-invasive CO monitoring and detected significant cardio-hemodynamic changes that conventional monitors could miss. EC can supplement traditional monitors and give attending anesthesiologists access to more of patients' vital information.

Lessons from the similarities and differences in fluid resuscitation between burns and sepsis: a bibliometric analysis

Background

Fluid is an essential component of initial resuscitation in sepsis or burns. Meanwhile, the optimal strategy of titrating fluids for both of the two conditions remains uncertain. In this bibliometric analysis, we compared the similarities and differences in fluid resuscitation between sepsis and burns in recent publications.

Methods

Literatures related to fluid resuscitation in either sepsis or burns were searched in the Web of Science database Core Collection from January 1, 1992, to December 31, 2022. CiteSpace and VOSviewer was used for bibliometric analysis.

Results

A total of 1,549 and 468 publications on fluid resuscitation in sepsis and burns were retrieved from 1992 to 2022. Based on the occurrences, 341 and 86 high-frequency keywords were screened out from sepsis and burns publications, respectively, which were similarly categorized into 5 clusters [i.e. "mechanisms of hypovolemia" (cluster 1), "titration of fluid" (cluster 2), "outcomes or complications" (cluster 3), "pathophysiological alternations" (cluster 4), and "fluid types and others" (cluster 5)]. The high-frequency keywords of the top 20 were more concentrated in cluster 3 and cluster 2, with "mortality" ranked the top in both sepsis and burns literature. Significantly, 3 keywords in cluster 2 ranked in the top 5, including "goal directed resuscitation" (the 3rd), fluid responsiveness (the 4th) and fluid balance (the 5th) in sepsis literature, while the keywords of "microvascular exchange" (cluster 1) and "abdominal compartment syndrome" (ACS, cluster 3) ranked at the second and the fifth place in burns publications. Keyword burst analysis demonstrated that the keyword with the highest burst strength (BS) was "formula" (BS = 5.88, 2008-2014), followed by management (BS = 4.79, 2012-2022), ACS (BS = 4.76, 2006-2010), and fluid creep (BS = 4.74, 2011-2016) in burn publications, but they were dobutamine (BS = 12.31, 1992-2008), cardiac output (BS = 9.79, 1993-2001), catecholamine (BS = 9.54, 1993-2006), and consumption (BS = 7.52, 1992-2006) in sepsis literature. Moreover, the most frequently cited article in either sepsis or burns was categorized into cluster 2, that investigated goal-directed fluid therapy for sepsis and formula improvement for burns resuscitation.

Conclusion

It was demonstrated that the research priorities in titrating fluid were mainly concentrated on targeting hemodynamics in sepsis vs. improving formula (which briefly calculates the increased microvascular permeability) in burns, while concerning of "outcomes and complications" in fluid resuscitation similarly after 1992. However, hemodynamics and microvascular permeability have been simultaneously well considered in few previous studies regarding fluid resuscitation in either sepsis or burns.

End-Expiratory Occlusion Test and Tidal Volume Challenge Test for Evaluating Fluid Responsiveness in Severe Traumatic Brain Injury, Septic Shock, and Acute Respiratory Distress Syndrome

INTRODUCTION

Fluid management in critically ill patients, particularly those with severe traumatic brain injury (TBI), septic shock, and acute respiratory distress syndrome (ARDS), presents a complex and multifaceted challenge. Dynamic tests such as the end-expiratory occlusion (EEO) test and tidal volume challenge (TVC) test are commonly used to assess fluid responsiveness, providing valuable insights into cardiovascular responses to changes in volume status. However, due to the unique risks and complications associated with these conditions, there is an increasing need to explore and evaluate alternative methods for predicting fluid responsiveness more safely and accurately in these critically ill patients.

METHODS

This study presents a prospective investigation conducted on patients with severe TBI, septic shock, and ARDS. Before administering a 100 mL colloid bolus, both the EEO and TVC tests were performed. Initial measurements of cardiac output (CO), cardiac index (CI), and pulse pressure variation (PPV) were recorded, followed by subsequent measurements after each test to assess the fluid responsiveness and cardiovascular changes in these critically ill patients.

RESULTS

Among the 180 participants, a more than 5% increase in CI during the EEO test was indicative of fluid responsiveness. Similarly, a 3.5% absolute increase in PPV during the TVC test suggested fluid responsiveness. The interrater reliability for the EEO test was observed to be 0.915, indicating strong agreement between raters, while for PPV, it was 0.637, reflecting moderate agreement. These values suggest that the EEO test shows a high degree of consistency between different evaluators, whereas the PPV measurement demonstrates a more moderate level of reliability.

CONCLUSION

In patients with severe TBI, septic shock, and ARDS who are receiving low tidal volume (VT) ventilation, both the EEO test for 15 seconds and the TVC method can be used to assess fluid responsiveness. However, it is important to note that the EEO test demonstrates greater reliability in this context.

A review of recent advances in anesthetic drugs for patients undergoing cardiac surgery

Inducing and maintaining general anesthesia requires a diverse set of medications. Currently, heart surgery anesthetic management does not adhere to any one standard protocol or set of drugs. To ensure steady circulatory function while providing sufficient sedation, anesthetic medications are carefully selected for cardiovascular operations. Among the opioids used most often in cardiac surgery are fentanyl, sufentanil, and remifentanil. As a cardiac anesthesiologist, your key responsibilities will be to maintain your patient's blood pressure (BP) and oxygen levels, reduce the frequency and intensity of ischemia events, and make it easy for them to get off of cardiopulmonary bypass (CPB) and supplemental oxygen fast. Additionally, new knowledge gaps have been identified as a result of developments in cardiac anesthetics, which must be addressed. The goal of the most recent developments in cardiac anesthesia has been to decrease risks and increase accuracy in patient outcomes during cardiac surgeries. Furthermore, new methods and tools are contributing to the evolution of cardiovascular anesthesia toward a more dynamic, patient-centered approach, with an eye on boosting safety, decreasing complications, and facilitating better recovery for patients. New medications and methods have emerged in the field of anesthetic pharmacology, aiming to improve anesthesia management, particularly for patients who have cardiovascular disease. Optimal cardiovascular stability, fewer side effects, and enhanced surgical recovery are achieved by use of these medications. We have reviewed all the different kinds of cardiac anesthetic techniques and medications in this research. We have also examined the many new anesthetic medicines that have been produced and used for individuals with cardiovascular issues. Next, we covered prospects in the realm of cardiovascular anesthesia and novel cardiac anesthetic drugs.

Assessing fluid responsiveness by using functional hemodynamic tests in critically ill patients: a narrative review and a profile-based clinical guide

Fluids are given with the purpose of increasing cardiac output (CO), but approximately only 50% of critically ill patients are fluid responders. Since the effect of a fluid bolus is time-sensitive, it diminuish within few hours, following the initial fluid resuscitation. Several functional hemodynamic tests (FHTs), consisting of maneuvers affecting heart-lung interactions, have been conceived to discriminate fluid responders from non-responders. Three main variables affect the reliability of FHTs in predicting fluid responsiveness: (1) tidal volume; (2) spontaneous breathing activity; (3) cardiac arrythmias. Most FTHs have been validated in sedated or even paralyzed ICU patients, since, historically, controlled mechanical ventilation with high tidal volumes was the preferred mode of ventilatory support. The transition to contemporary methods of invasive mechanical ventilation with spontaneous breathing activity impacts heart-lung interactions by modifying intrathoracic pressure, tidal volumes and transvascular pressure in lung capillaries. These alterations and the heterogeneity in respiratory mechanics (that is present both in healthy and injured lungs) subsequently influence venous return and cardiac output. Cardiac arrythmias are frequently present in critically ill patients, especially atrial fibrillation, and intuitively impact on FHTs. This is due to the random CO fluctuations. Finally, the presence of continuous CO monitoring in ICU patients is not standard and the assessment of fluid responsiveness with surrogate methods is clinically useful, but also challenging. In this review we provide an algorithm for the use of FHTs in different subgroups of ICU patients, according to ventilatory setting, cardiac rhythm and the availability of continuous hemodynamic monitoring.

High-throughput microfluidic spheroid technology for early detection of colistin-induced nephrotoxicity with gradient-based analysis

Colistin is essential for treating multidrug-resistant Gram-negative bacterial infections but has significant nephrotoxic side effects. Traditional approaches for studying colistin's nephrotoxicity are challenged by the rapid metabolism of its prodrug, colistin methanesulfonate and the difficulty of obtaining adequate plasma from critically ill patients. To address these challenges, we developed the Spheroid Nephrotoxicity Assessing Platform (SNAP), a microfluidic device that efficiently detects colistin-induced toxicity in renal proximal tubular epithelial cell (RPTEC) spheroids within 48 hours using just 200 μL of patient plasma. Our findings demonstrate that SNAP not only promotes higher expression of kidney-specific markers aquaporin-1 (AQP1) and low-density lipoprotein receptor-related protein 2 (LRP2) compared to traditional two-dimensional (2D) cultures, but also exhibits increased sensitivity to colistin, with significant toxicity detected at concentrations of 50 μg ml-1 and above. Notably, SNAP's non-invasive method did not identify nephrotoxicity in plasma from healthy donors, thereby confirming its physiological relevance and showcasing superior sensitivity over 2D cultures, which yielded false-positive results. In clinical validation, SNAP accurately identified patients at risk of colistin-induced nephrotoxicity with 100% accuracy for both early and late onset and demonstrated a 75% accuracy rate in predicting the non-occurrence of nephrotoxicity. These results underline the potential of SNAP in personalized medicine, offering a non-invasive, precise and efficient tool for the assessment of antibiotic-induced nephrotoxicity, thus enhancing the safety and efficacy of treatments against resistant bacterial infections.

Effect of low-dose norepinephrine combined with goal-directed fluid therapy on postoperative pulmonary complications in lung surgery: A prospective randomized controlled trial

STUDY OBJECTIVE

Postoperative pulmonary complications (PPCs), the predominant complications following lung surgery, are closely associated with intraoperative fluid therapy. This study investigates whether continuous low-dose norepinephrine infusion combined with goal-directed fluid therapy (GDFT) reduced the risk of PPCs after lung surgery relative to either GDFT alone or standard fluid treatment.

DESIGN

A prospective, randomized controlled trial.

SETTING

The First Affiliated Hospital of Anhui Medical University, Anhui, China.

PATIENTS

The study included 184 patients undergoing elective thoracoscopic lung resection surgery.

INTERVENTIONS

Patients were randomized into three groups based on different fluid treatment regimens: Group C received standard fluid treatment, Group G received GDFT, and Group N received continuous low-dose norepinephrine infusion combined with GDFT.

MEASUREMENTS

The primary outcome was the incidence of PPCs, including respiratory infection, atelectasis, pneumothorax, pleural empyema, respiratory failure, pulmonary embolism and bronchopleural fistula, during the postoperative hospital stay. Secondary outcomes were hemodynamic variables and arterial blood gases. Additional recorded parameters included other postoperative complications such as bleeding, postoperative re-intubation, re-hospitalization within 30 days, and the length of hospital stay.

MAIN RESULTS

Group N showed a significantly lower PPCs incidence during hospitalization compared to Group C (11.5 % vs 27.9 %; odds ratio, 2.98; 95 % confidence interval, 1.17-8.31; P = 0.023). No significant difference in PPCs was found between Group N and Group G (11.5 % vs 14.5 %; odds ratio, 1.31; 95 % confidence interval, 0.46-3.91; P = 0.616). Additionally, there were no significant differences among the three groups in the components of PPCs. Group N showed higher mean arterial pressure and stroke volume index intraoperatively compared to Group C.

CONCLUSIONS

Continuous low-dose norepinephrine infusion combined with GDFT reduced PPCs incidence in elective lung surgery patients compared with standard fluid management, but showed no difference compared to GDFT alone.

CLINICAL TRIAL REGISTRATION

ChiCTR2200064081.

Application of ultrasound-guided inferior vena cava collapsibility measurement in volume assessment for patients undergoing single-shot spinal anesthesia in total hip arthroplasty

To explore the value of ultrasound in volume assessment during the perioperative period of single-shot spinal anesthesia for total hip arthroplasty. A total of 100 patients undergoing elective surgery under spinal anesthesia at our hospital from January 2022 to January 2024 were selected. Transthoracic echocardiography was used to measure the diameter of the abdominal aorta (Ao) before anesthesia (T1), 10 minutes after anesthesia (T2), and 30 minutes after anesthesia (T3). The inferior vena cava collapsibility index (IVC-CI) and the ratio of IVCe to Ao (IVCe/Ao) were calculated. A volume load test was performed 10 minutes after anesthesia. Based on the increase in stroke volume (ΔSV) after the volume load test, patients were divided into a volume-responsive group (ΔSV ≥ 15%) and a volume-nonresponsive group (ΔSV < 15%). The reliability of inferior vena cava parameters in predicting hypotension after spinal anesthesia and the value in predicting volume responsiveness postanesthesia were evaluated using ROC curves. A total of 100 patients were enrolled, 18 were withdrawn, and a total of 82 patients were included. After the volume load test, the parameters of the volume response group and the volume nonresponse group were basically consistent, and the difference was not statistically significant (P > .05). The SV of volume reaction group was significantly higher than that of volume no reaction group (P < .05). The incidence of hypotension in the volume response group was higher than that in the non-volume response group (51.28% vs 11.63%, χ2 = 15.174, P < .01). The AUC for volume reactivity prediction using IVCe, IVCi, IVC-CI, and IVCe/Ao were 0.62, 0.71, 0.70, and 0.72, respectively. IVCi, IVC-CI, and IVCe/Ao were significant predictors of volume reactivity (P < .05). The AUC predicting persistent hypotension after spinal anesthesia using IVCe, IVCi, IVC-CI, and IVCe/Ao were 0.78, 0.79, 0.70, and 0.84, respectively. IVCe, IVCi, IVC-CI, and IVCe/Ao can predict volume reactivity before anesthesia. IVCi, IVC-CI, and IVCe/Ao predicted persistent hypotension in patients with spinal anesthesia after anesthesia, and IVCe/Ao showed the best predictive effect. Thus, IVCe/Ao is a reliable parameter for predicting persistent hypotension and assessing volumetric reactivity.

Use of the cardiac power index to predict fluid responsiveness in the prone position: a proof-of-concept study

BACKGROUND

The primary aim of this proof-of-concept study was to investigate whether the Cardiac Power Index (CPI) could be a novel alternative method to assess fluid responsiveness in the prone position.

METHODS

Patients undergoing scheduled elective lumbar spine surgery in the prone position under general anesthesia were enrolled in the criteria of patients aged 19-75 years with American Society of Anesthesiologists (ASA) physical status I-II. The hemodynamic variables were evaluated before and after changes in posture after administering a colloid bolus (5 mL.kg-1) in the prone position. Fluid responsiveness was defined as an increase in the Stroke Volume Index (SVI) ≥ 10%.

RESULTS

A total of 28 patients were enrolled. In responders, the CPI (median [1/4Q-3/4Q]) decreased to 0.34 [0.28-0.39] W.m-2 (p = 0.035) after the prone position. After following fluid loading, CPI increased to 0.48 [0.37-0.52] W.m-2 (p < 0.008), and decreased SVI (median [1/4Q-3/4Q]) after prone increased from 26.0 [24.5-28.0] mL.m-2 to 33.0 [31.0-37.5] mL.m-2 (p = 0.014). Among non-responders, CPI decreased to 0.43 [0.28-0.53] W.m-2 (p = 0.011), and SVI decreased to 29.0 [23.5-34.8] mL.m-2 (p < 0.009). CPI exhibited predictive capabilities for fluid responsiveness as a receiver operating characteristic curve of 0.78 [95% Confidence Interval, 0.60-0.95; p = 0.025].

CONCLUSION

This study suggests the potential of CPI as an alternative method to existing preload indices in assessing fluid responsiveness in clinical scenarios, offering potential benefits for responders and non-responders.

[Functional hemodynamic monitoring]

BACKGROUND

Critically ill patients in the intensive care unit require intensified monitoring to control the treatment with volume and/or vasoactive substances.

RESEARCH QUESTION

What role does functional hemodynamic monitoring play in controlling treatment and what techniques are used to manage this?

MATERIAL AND METHODS

Review of the current literature.

RESULTS AND DISCUSSION

Precise knowledge of the physiology of the cardiovascular system as well as the pathophysiology of individual clinical pictures and the possibilities of invasive and noninvasive monitoring are the prerequisites for the indications, implementation and interpretation of functional hemodynamic monitoring. An understanding of the heart-lung interaction and the influence of invasive ventilation on the volumetric target parameters, such as stroke volume variation, systolic pressure variation and pulse pressure variation as well as sonography of the inferior vena cava are indispensable prerequisites for the question of volume responsiveness. Other maneuvers, such as the passive leg raising test, can be very helpful when deciding on volume administration in everyday clinical practice. Static parameters such as central venous pressure generally play no role and if any only a subordinate one.

Sublingual microcirculatory assessment on admission independently predicts the outcome of old intensive care patients suffering from shock

Shock is a life-threatening condition. This study evaluated if sublingual microcirculatory perfusion on admission is associated with 30-day mortality in older intensive care unit (ICU) shock patients. This trial prospectively recruited ICU patients (≥ 80 years old) with arterial lactate above 2 mmol/L, requiring vasopressors despite adequate fluid resuscitation, regardless of shock cause. All patients received sequential sublingual measurements on ICU admission (± 4 h) and 24 (± 4) hours later. The primary endpoint was 30-day mortality. From September 4th, 2022, to May 30th, 2023, 271 patients were screened, and 44 included. Patients were categorized based on the median percentage of perfused small vessels (sPPV) into those with impaired and sustained microcirculation. 71% of videos were of good or acceptable quality without safety issues. Patients with impaired microcirculation had significantly shorter ICU and hospital stays (p = 0.015 and p = 0.019) and higher 30-day mortality (90.0% vs. 62.5%, p = 0.036). Cox regression confirmed the independent association of impaired microcirculation with 30-day mortality (adjusted hazard ratio 3.245 (95% CI 1.178 to 8.943, p = 0.023). Measuring sublingual microcirculation in critically ill older patients with shock on ICU admission is safe, feasible, and provides independent prognostic information about outcomes.Trial registration NCT04169204.

Comparison of two different preload targets of stroke volume variation during kidney transplantation: a randomised controlled trial

INTRODUCTION

Maintaining adequate preload during kidney transplantation (KT) is important for graft function. We evaluated whether a high or low normal target for a dynamic preload index of stroke volume variation (SVV) would impact graft function during living donor KT.

METHODS

We compared haemodynamic management algorithms using two different targets of SVV: SVV6% group (n = 30) versus SVV12% group (n = 30). Crystalloids were administered to achieve SVV less than the assigned target. Neutrophil gelatinase-associated lipocalin (NGAL) level at the end of surgery was compared. We also compared the incidence of delayed graft function (DGF), daily serum creatinine level and glomerular filtration rate (GFR) until 2 weeks postoperatively.

RESULTS

The total amount of crystalloids administered was significantly different between the SVV6% and SVV12% groups (median [interquartile range] 2,250 [1,700-3,600] vs. 1,350 [1,050-1,900], P < 0.001). There was no significant difference in NGAL level at the end of the operation between the SVV6% and SVV12% groups (395 [234-560] vs. 518 [346-654], P = 0.115). The incidence of DGF was not significantly different, and there was no significant difference in the postoperative serum creatinine levels or GFR between the groups.

CONCLUSIONS

Our randomised trial demonstrated that an SVV target of either 6% or 12% could be adequate as a preload management target for postoperative graft function during living donor KT. However, given the low incidence of DGF in living donor KT and type II error, our study should be interpreted carefully and further studies for deceased donor KT are required.

The Ability of Military Critical Care Air Transport Members to Visually Estimate Percent Systolic Pressure Variation

INTRODUCTION

Inappropriate fluid management during patient transport may lead to casualty morbidity. Percent systolic pressure variation (%SPV) is one of several technologies that perform a dynamic assessment of fluid responsiveness (FT-DYN). Trained anesthesia providers can visually estimate and use %SPV to limit the incidence of erroneous volume management decisions to 1-4%. However, the accuracy of visually estimated %SPV by other specialties is unknown. The aim of this article is to determine the accuracy of estimated %SPV and the incidence of erroneous volume management decisions for Critical Care Air Transport (CCAT) team members before and after training to visually estimate and utilize %SPV.

MATERIAL AND METHODS

In one sitting, CCAT team providers received didactics defining %SPV and indicators of fluid responsiveness and treatment with %SPV ≤7 and ≥14.5 defining a fluid nonresponsive and responsive patient, respectively; they were then shown ten 45-second training arterial waveforms on a simulated Propaq M portable monitor's screen. Study subjects were asked to visually estimate %SPV for each arterial waveform and queried whether they would treat with a fluid bolus. After each training simulation, they were told the true %SPV. Seven days post-training, the subjects were shown a different set of ten 45-second testing simulations and asked to estimate %SPV and choose to treat, or not. Nonparametric limits of agreement for differences between true and estimated %SPV were analyzed using Bland-Altman graphs. In addition, three errors were defined: (1) %SPV visual estimate errors that would label a volume responsive patient as nonresponsive, or vice versa; (2) incorrect treatment decisions based on estimated %SPV (algorithm application errors); and (3) incorrect treatment decisions based on true %SPV (clinically significant treatment errors). For the training and testing simulations, these error rates were compared between, and within, provider groups.

RESULTS

Sixty-one physicians (MDs), 64 registered nurses (RNs), and 53 respiratory technicians (RTs) participated in the study. For testing simulations, the incidence and 95% CI for %SPV estimate errors with sufficient magnitude to result in a treatment error were 1.4% (0.5%, 3.2%), 1.6% (0.6%, 3.4%), and 4.1% (2.2%, 6.9%) for MDs, RNs, and RTs, respectively. However, clinically significant treatment errors were statistically more common for all provider types, occurring at a rate of 7%, 10%, and 23% (all P < .05). Finally, students did not show clinically relevant reductions in their errors between training and testing simulations.

CONCLUSIONS

Although most practitioners correctly visually estimated %SPV and all students completed the training in interpreting and applying %SPV, all groups persisted in making clinically significant treatment errors with moderate to high frequency. This suggests that the treatment errors were more often driven by misapplying FT-DYN algorithms rather than by inaccurate visual estimation of %SPV. Furthermore, these errors were not responsive to training, suggesting that a decision-making cognitive aid may improve CCAT teams' ability to apply FT-DYN technologies.

Evaluation of Electrical Cardiometry to Assess Fluid Responsiveness in Patients with Acute Circulatory Failure: A Comparative Study with Transthoracic Echocardiography

Aim

Acute circulatory failure is commonly encountered in critically ill patients, that requires fluid administration as the first line of treatment. However, only 50% of patients are fluid-responsive. Identification of fluid responders is essential to avoid the harmful effects of overzealous fluid therapy. Electrical cardiometry (EC) is a non-invasive bedside tool and has proven to be as good as transthoracic echocardiography (TTE) to track changes in cardiac output. We aimed to look for an agreement between EC and TTE for tracking changes in cardiac output in adult patients with acute circulatory failure before and after the passive leg-raising maneuver.

Materials and methods

Prospective comparative study, conducted at a Tertiary Care Teaching Hospital.

Results

We recruited 125 patients with acute circulatory failure and found 42.4% (53 out of 125) to be fluid-responsive. The Bland-Altman plot analysis showed a mean difference of 2.08 L/min between EC and TTE, with a precision of 3.8 L/min. The limits of agreement (defined as bias ± 1.96SD), were -1.7 L/min and 5.8 L/min, respectively. The percentage of error between EC and TTE was 56% with acceptable limits of 30%.

Conclusion

The percentage error beyond the acceptable limit suggests the non-interchangeability of the two techniques. More studies with larger sample sizes are required to establish the interchangeability of EC with TTE for tracking changes in cardiac output in critically ill patients with acute circulatory failure.

How to cite this article

Sharma S, Ramachandran R, Rewari V, Trikha A. Evaluation of Electrical Cardiometry to Assess Fluid Responsiveness in Patients with Acute Circulatory Failure: A Comparative Study with Transthoracic Echocardiography. Indian J Crit Care Med 2024;28(7):650-656.

Are We Always Right? Evaluation of the Performance and Knowledge of the Passive Leg Raise Test in Detecting Volume Responsiveness in Critical Care Patients: A National German Survey

Background: In hemodynamically unstable patients, the passive leg raise (PLR) test is recommended for use as a self-fluid challenge for predicting preload responsiveness. However, to interpret the hemodynamic effects and reliability of the PLR, the method of performing it is of the utmost importance. Our aim was to determine the current practice of the correct application and interpretation of the PLR in intensive care patients. Methods: After ethical approval, we designed a cross-sectional online survey with a short user-friendly online questionnaire. Using a random sample of 1903 hospitals in Germany, 182 hospitals with different levels of care were invited via an email containing a link to the questionnaire. The online survey was conducted between December 2021 and January 2022. All critical care physicians from different medical disciplines were surveyed. We evaluated the correct points of concern for the PLR, including indication, contraindication, choice of initial position, how to interpret and apply the changes in cardiac output, and the limitations of the PLR. Results: A total of 292 respondents participated in the online survey, and 283/292 (97%) of the respondents completed the full survey. In addition, 132/283 (47%) were consultants and 119/283 (42%) worked at a university medical center. The question about the performance of the PLR was answered correctly by 72/283 (25%) of the participants. The limitations of the PLR, such as intra-abdominal hypertension, were correctly selected by 150/283 (53%) of the participants. The correct effect size (increase in stroke volume ≥ 10%) was correctly identified by 217/283 (77%) of the participants. Conclusions: Our results suggest a considerable disparity between the contemporary practice of the correct application and interpretation of the PLR and the practice recommendations from recently published data at German ICUs.

Influence of fluid accumulation on major adverse kidney events in critically ill patients - an observational cohort study

BACKGROUND

Fluid accumulation (FA) is known to be associated with acute kidney injury (AKI) during intensive care unit (ICU) stay but data on mid-term renal outcome is scarce. The aim of this study was to investigate the association between FA at ICU day 3 and major adverse kidney events in the first 30 days after ICU admission (MAKE30).

METHODS

Retrospective, single-center cohort study including adult ICU patients with sufficient data to compute FA and MAKE30. We defined FA as a positive cumulative fluid balance greater than 5% of bodyweight. The association between FA and MAKE30, including its sub-components, as well as the serum creatinine trajectories during ICU stay were examined. In addition, we performed a sensitivity analysis for the stage of AKI and the presence of chronic kidney disease (CKD).

RESULTS

Out of 13,326 included patients, 1,100 (8.3%) met the FA definition. FA at ICU day 3 was significantly associated with MAKE30 (adjusted odds ratio [aOR] 1.96; 95% confidence interval [CI] 1.67-2.30; p < 0.001) and all sub-components: need for renal replacement therapy (aOR 3.83; 95%CI 3.02-4.84), persistent renal dysfunction (aOR 1.72; 95%CI 1.40-2.12), and 30-day mortality (aOR 1.70; 95%CI 1.38-2.09), p all < 0.001. The sensitivity analysis showed an association of FA with MAKE30 independent from a pre-existing CKD, but exclusively in patients with AKI stage 3. Furthermore, FA was independently associated with the creatinine trajectory over the whole observation period.

CONCLUSIONS

Fluid accumulation is significantly associated with MAKE30 in critically ill patients. This association is independent from pre-existing CKD and strongest in patients with AKI stage 3.

Evaluation of risk factors for postoperative neurologic intensive care admission after brain tumor craniotomy: A single-center longitudinal study

Background and Aims

Perioperative variable parameters can be significant risk factors for postoperative intensive care unit (ICU) admission after elective craniotomy for intracranial neoplasm, as assessed by various scoring systems such as Cranio Score. This observational study evaluates the relationship between these factors and early postoperative neurological complications necessitating ICU admission.

Material and Methods

In total, 119 patients, aged 18 years and above, of either sex, American Society of Anesthesiologists (ASA) grades I-III, scheduled for elective craniotomy and tumor excision were included. The primary objective was to evaluate the relationship between perioperative risk factors and the incidence of early postoperative complications as a means of validation of the Cranio Score. The secondary outcomes studied were 30-day postoperative morbidity/mortality and the association with patient-related risk factors.

Results

Forty-five of 119 patients (37.82%) required postoperative ICU care with the mean duration of ICU stay being 1.92 ± 4.91 days. Tumor location (frontal/infratemporal region), preoperative deglutition disorder, Glasgow Coma Scale (GCS) less than 15, motor deficit, cerebellar deficit, midline shift >3 mm, mass effect, tumor size, use of blood products, lateral position, inotropic support, elevated systolic/mean arterial pressures, and duration of anesthesia/surgery were associated with a higher incidence of ICU care. Maximum (P = 0.035, AOR = 1.130) and minimum systolic arterial pressures (P = 0.022, Adjusted Odds Ratio (AOR) = 0.861) were the only independent risk factors. Cranio Score was found to be an accurate predictor of complications at a cut-off point of >10.52%. The preoperative motor deficit was the only independent risk factor associated with 30-day morbidity (AOR = 4.66).

Conclusion

Perioperative hemodynamic effects are an independent predictor of postoperative ICU requirement. Further Cranio Score is shown to be a good scoring system for postoperative complications.

Surviving 20 Hours of Critical Avalanche Burial and a Core Temperature of 22.5 °C

A 24-year-old male snowboarder was buried in an avalanche for 20 h and rescued on the next day at a depth of 2.3 m below the snow surface. A large air pocket was noted in front of his mouth and nose. He was responsive but moved restlessly and uncoordinatedly. The epitympanic temperature was 22.5 °C. He was bradycardic (35/min), and a right bundle branch block with Osborn waves was noted. Rewarming (1 °C/h) was initiated with continuous hemodialysis; core temperature raised to 29.8 °C within 4 h. At 30 °C he became conscious. With rewarming, the heart rate increased to 90 beats per minute and the ECG changes disappeared; nonfreezing cold injuries were noted. On the next day, his pulmonary function deteriorated-fluid overload of 9 L since admission was diagnosed. With spontaneous diuresis, the situation improved. On Day 4, the neurologist reported subtle polyneuropathy in both legs secondary to hypothermia, without tendency to regress. This case occurred more than 20 years ago but has not been reported yet. To this day, this is the third-longest critical avalanche burial ever reported. We discuss the circumstances of this accident, the clinical course, and how treatment has changed since 2000.

Measurement of non-invasive cardiac output during cycling exercise in ischemic stroke inpatients: A pilot study

BACKGROUND

Cardiac dysfunction accompanies acute ischemic stroke and affects the effective implementation of early rehabilitation interventions. There is a lack of reference hemodynamic data on cardiac function in the subacute phase of ischemic stroke.

OBJECTIVE

In this study, we aimed to identify appropriate cardiac parameters for exercise training utilizing a pilot study.

METHODS

We used a transthoracic electrical bioimpedance non-invasive cardiac output measurement (NICOM) device to monitor cardiac function in real time for two groups [i.e., subacute ischemic stroke inpatients group (n= 10) and healthy control group (n= 11)] using a cycling exercise experiment. The parameters of both groups were compared to highlight the cardiac dysfunction in the subacute phase in patients with ischemic stroke.

RESULTS

We considered stroke volume index (SVI) and systemic vascular resistance index (SVRi) as the primary outcomes, and there was significant intragroup difference (stroke group: P< 0.001; control group: P< 0.001, using one-way ANOVA) and significant intergroup difference at each individual time segment (P< 0.01, using independent t-test). Among the secondary outcomes, i.e., cardiac index (CI), ejection fraction (EF), end-diastolic volume (EDV), and cardiac contraction index (CTI), we found significant intergroup differences in CI, EF, and CTI scores (P< 0.01, using independent t-test). Significant interaction with respect to time and group were seen only in the SVRi and CI scores (P< 0.01, using two-way ANOVA). There was no significant inter- or intra-group differences in EDV scores.

CONCLUSION

SVRI, SVI, and CI values highlight cardiac dysfunction in stroke patients the most. At the same time, these parameters suggest that cardiac dysfunction in stroke patients may be closely related to the increased peripheral vascular resistance caused by infarction and the limitation of myocardial systolic function.

Prediction of fluid responsiveness for patients in shock using a ventilator disconnection test combined with the pulse contour-derived cardiac index

BACKGROUND

Finding a simple and reliable method to predict and assess fluid responsiveness has long been of clinical interest.

OBJECTIVE

To investigate the predictive value of a ventilator disconnection (DV) test combined with the pulse contour-derived cardiac output (PiCCO) index on fluid responsiveness for patients in shock.

METHODS

Thirty-two patients were chosen for the study. Patients who were in shock, received mechanical ventilation, and met the inclusion criteria were selected. Patients were divided into a fluid-responsive group (14 patients) and fluid-unresponsive group (18 patients) based on whether the increase in cardiac index (Δ CI) was > 10% or not, respectively, following the fluid challenge test. Changes in heart rate, pulse oximeter-measured oxygen saturation, mean arterial pressure (MAP), and CI before and after passive leg raising (PLR), DV, and fluid challenge tests were observed. We used Pearson's correlation coefficient to analyze an increase in the MAP (Δ MAP) and Δ CI before and after the PLR, DV, and fluid challenge tests; the sensitivity and specificity of the Δ MAP and Δ CI in the PLR and DV tests for predicting fluid response were also analyzed by plotting the receiver operating characteristic (ROC) curves.

RESULTS

CI results in the PLR and DV tests, as well as the fluid challenge test, were significantly higher in the fluid-responsive group compared with before the test (P< 0.05). The Δ CI before and after the PLR, DV, and fluid challenge tests were positively correlated among patients in the fluid-responsive group. The area under the ROC curve for the post-PLR test CI and the post-DV CI for predicting fluid responsiveness was 0.869 (95% confidence interval (CI) [0.735-1.000, P= 0.000]) and 0.937 (95% CI [0.829-1.000, P= 0.000]), respectively, in patients in the fluid-responsive group. The sensitivity and specificity of the post-DV CI for predicting fluid responsiveness in all patients was 100.0% and 88.9%, respectively, using a 5% increase as the cut-off value.

CONCLUSION

Application of DV, combined with PiCCO, has a high predictive value for fluid responsiveness among patients in shock.

Carotid Blood Flow as a Surrogate for Pulse Contour Analysis in Assessment of Fluid Responsiveness: A Prospective, Observational, Single-Centre Study (Contour Study)

Background and objectives The quest for an accurate and reliable non-invasive method of assessing cardiac output in critically ill patients is still ongoing. Carotid artery Doppler is a promising non-invasive, reproducible, and feasible bedside monitor. So we compared the change in cardiac output derived from arterial pressure waveforms (pulse contour analysis) with that from carotid artery Doppler-derived measurements, in post-major elective abdominal surgery patients. Materials and methods We conducted a prospective observational study in 30 adult post-major elective abdominal surgery patients admitted to the Gastroenterology and Liver Transplant intensive care unit postoperatively on mechanical ventilator support, who were found to be fluid responsive clinically on passive leg raise (PLR) test. Demographics and vasopressor support were recorded. Hemodynamic parameters including heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), cardiac output (CO) using arterial pulse contour analysis (Vigileo monitor/FloTrac® sensor; Edwards Lifesciences, Irvine, California, United States), and carotid blood flow (CBF) were recorded on the baseline, pre- and post- PLR, and post fluid bolus administration. Balanced salt solution at the rate of 6ml/kg over 20 minutes was given as a fluid bolus. Results Of the 30 patients who were included in the study, 16 patients (53.3%) were on vasopressor support, mean (± SD) age of the patients was 52.93 (± 8.13) years. There was a significant increase in the SBP (mmHg) pre- to post-PLR, that is, 112.2±15.57 and 118.7±14.96, respectively (p-value = 0.001). Also from pre-PLR to post-fluid bolus administration, the increase in SBP was significant, 112.2±15.57 and 121.93±13.96, respectively (p-value = 0.001). The change in cardiac output measured using Vigileo and CBF from pre- to post-PLR (7.66±1.45 to 9.14±1.76, p< 0.001 for Vigileo and 8.10±1.66 to 9.72±1.99, p<0.001 for CBF) and pre-PLR to post fluid administration (7.66±1.45 to 9.39±1.77, p< 0.001 for Vigileo and 8.10±1.66 to 10.31±2.26, p< 0.001 for CBF) were significant. There was a positive correlation between the change in cardiac output as measured from arterial pulse contour analysis technique (Vigileo) and that measured from CBF (r=0.884) pre- and post-PLR. There was a significant correlation between cardiac output measurements derived from two techniques, before PLR, after PLR, and after fluid expansion (p< 0.001 for each variable). The change in cardiac output before PLR and after fluid expansion was also correlated by both the techniques (correlation coefficient being, r=0.781). Conclusion There was a significant positive correlation of the CO (absolute and change) measurements pre- and post-interventions (that is, PLR and fluid bolus administration) as made by pulse contour analysis (Vigileo) and by CBF in post-surgical patients. Pulse wave Doppler of CBF could be used as a surrogate for invasive measures of CO measurement for prediction of fluid responsiveness in this subgroup. Further larger studies can be performed to validate the same.

Clinical outcomes of a prospective randomized comparison of bioreactance monitoring versus pulse-contour analysis in a stroke-volume based goal-directed fluid resuscitation protocol in brain-dead organ donors

Eighty percent of brain-dead (BD) organ donors develop hypotension and are frequently hypovolemic. Fluid resuscitation in a BD donor is controversial. We have previously published our 4-h goal-directed stroke volume (SV)-based fluid resuscitation protocol which significantly decreased time on vasopressors and increased transplanting four or more organs. The SV was measured by pulse-contour analysis (PCA) or an esophageal doppler monitor, both of which are invasive. Thoracic bioreactance (BR) is a non-invasive portable technology that measures SV but has not been studied in BD donors. We performed a randomized prospective comparative study of BR versus PCA technology in our fluid resuscitation protocol in BD donors. Eighty-four donors (53.1%) were randomized to BR and 74 donors to PCA (46.8%). The two groups were well matched based on 24 demographic, social, and initial laboratory factors, without any significant differences between them. There was no difference in the intravenous fluid infused over the 4-h study period [BR 2271 ± 823 vs. PCA 2230 ± 962 mL; p = .77]. There was no difference in the time to wean off vasopressors [BR 108.8 ± 61.8 vs. PCA 150.0 ± 68 min p = .07], nor in the number of donors off vasopressors at the end of the protocol [BR 16 (28.6%) vs. PCA 15 (29.4%); p = .92]. There was no difference in the total number of organs transplanted per donor [BR 3.25 ± 1.77 vs. PCA 3.22 ± 1.75; p = .90], nor in any individual organ transplanted. BR was equivalent to PCA in clinical outcomes and provides a simple, non-invasive, portable technology to monitor fluid resuscitation in organ donors.

Reviving Hope: A Comprehensive Review of Post-resuscitation Care in Pediatric ICUs After Cardiac Arrest

This comprehensive review thoroughly examines post-resuscitation care in pediatric ICUs (PICUs) following cardiac arrest. The analysis encompasses adherence to resuscitation guidelines, advances in therapeutic interventions, and the nuanced management of neurological, cardiovascular, and respiratory considerations during the immediate post-resuscitation phase. Delving into the complexities of long-term outcomes, cognitive and developmental considerations, and rehabilitation strategies, the review emphasizes the importance of family-centered care for pediatric survivors. A call to action is presented, urging continuous education, research initiatives, and quality improvement efforts alongside strengthened multidisciplinary collaboration and advocacy for public awareness. Through implementing these principles, healthcare providers and systems can collectively contribute to ongoing advancements in pediatric post-resuscitation care, ultimately improving outcomes and fostering a culture of excellence in pediatric critical care.

Impact of clinical pharmacist's interventions on clinical outcomes in appropriate use of colistin: a prospective pre-post intervention study

This study aims to evaluate the clinical pharmacist's contribution impact on the appropriate use of colistin. Our study was conducted prospectively in patients in the Internal Diseases Intensive Care Unit of Gazi University Medical Faculty Hospital for eight months. The first four months of the study were with the observation group, while the next four months were with the intervention group. The study determined how the active participation of clinical pharmacists had affected the appropriateness of colistin use. The results showed that the appropriate use of colistin was higher in the intervention group than in the observational group; furthermore, incidence of nephrotoxicity was lower. The difference between both groups was statistically significant (p < 0.001, p < 0.05), respectively. This study showed that the clinical pharmacist's active intervention by following the patients increased the frequency and percentage of the appropriate use of colistin. This decreased the incidence of nephrotoxicity, colistin's most important side effect.

Research Progress on the Mechanism and Management of Septic Cardiomyopathy: A Comprehensive Review

Sepsis is defined as a kind of life-threatening organ dysfunction due to a dysregulated host immune response to infection and is a leading cause of mortality in the intensive care unit. Sepsis-induced myocardial dysfunction, also called septic cardiomyopathy, is a common and serious complication in patients with sepsis, which may indicate a bad prognosis. Although efforts have been made to uncover the pathophysiology of septic cardiomyopathy, a number of uncertainties remain. This article sought to review available literature to summarize the existing knowledge on current diagnostic tools and biomarkers, pathogenesis, and treatments for septic cardiomyopathy.

Reliability of point-of-care ultrasound to evaluate fluid tolerance performed by critical care residents

BACKGROUND

Patients with hypotension usually receive intravenous fluids, but only 50% will respond to fluid administration. We aimed to assess the intra and interobserver agreement to evaluate fluid tolerance through diverse ultrasonographic methods.

METHODS

We prospectively included critically ill patients on mechanical ventilation. One trained intensivist and two intensive care residents obtained the left ventricular outflow tract velocity-time integral (VTI) variability, inferior vena cava (IVC) distensibility index, internal jugular vein (IJV) distensibility index, and each component of the venous excess ultrasound (VExUS) system. We obtained the intraclass correlation coefficient (ICC) and Gwet's first-order agreement coefficient (AC1), as appropriate.

RESULTS

We included 32 patients. In-training observers were unable to assess the VTI-variability in two patients. The interobserver agreement was moderate to evaluate the IJV-distensibility index (AC1 0.54, CI 95% 0.29-0.80), fair to evaluate VTI-variability (AC1 0.39, CI 95% 0.12-0.66), and absent to evaluate the IVC-distensibility index (AC1 0.19, CI 95% - 0.07 to 0.44). To classify patients according to their VExUS grade, the intraobserver agreement was good, and the interobserver agreement was moderate (AC1 0.52, CI 95% 0.34-0.69).

CONCLUSIONS

Point-of-care ultrasound is frequently used to support decision-making in fluid management. However, we observed that the VTI variability and IVC-distensibility index might require further training of the ultrasound operators to be clinically useful. Our findings suggest that the IJV-distensibility index and the VExUS system have acceptable reproducibility among in-training observers.

Effects of tidal volume challenge on the reliability of plethysmography variability index in hepatobiliary and pancreatic surgeries: a prospective interventional study

BACKGROUND

The plethysmography variability index (PVI) is a non-invasive, real-time, and automated parameter for evaluating fluid responsiveness, but it does not reliably predict fluid responsiveness during low tidal volume (VT) ventilation. We hypothesized that in a 'tidal volume challenge' with a transient increase in tidal volume from 6 to 8 ml Kg- 1, the changes in PVI could predict fluid responsiveness reliably.

METHOD

We performed a prospective interventional study in adult patients undergoing hepatobiliary or pancreatic tumor resections and receiving controlled low VT ventilation. The values for PVI, perfusion index, stroke volume variation, and stroke volume index (SVI) were recorded at baseline VT of 6 ml Kg- 1, 1 min after the VT challenge (8 ml Kg- 1), 1 min after VT 6 ml Kg- 1 reduced back again, and then 5 min after crystalloid fluid bolus 6 ml kg- 1 (actual body weight) administered over 10 min. The fluid responders were identified by SVI rise ≥ 10% after the fluid bolus.

RESULTS

The area under the receiver operating characteristic curve for PVI value change (ΔPVI6-8) after increasing VT from 6 to 8 ml Kg- 1 was 0.86 (95% confidence interval, 0.76-0.96), P < 0.001, 95% sensitivity, 68% specificity, and with best cut-off value of absolute change (ΔPVI6-8) = 2.5%.

CONCLUSION

In hepatobiliary and pancreatic surgeries, tidal volume challenge improves the reliability of PVI for predicting fluid responsiveness and changes in PVI values obtained after tidal volume challenge are comparable to the changes in SVI.

Performance of four cardiac output monitoring techniques vs. intermittent pulmonary artery thermodilution during a modified passive leg raise maneuver in isoflurane-anesthetized dogs

Objective

This study investigated the performance among four cardiac output (CO) monitoring techniques in comparison with the reference method intermittent pulmonary artery thermodilution (iPATD) and their ability to diagnose fluid responsiveness (FR) during a modified passive leg raise (PLRM) maneuver in isoflurane-anesthetized dogs undergoing acute blood volume manipulations. The study also examined the simultaneous effect of performing the PLRM on dynamic variables such as stroke distance variation (SDV), peak velocity variation (PVV), and stroke volume variation (SVV).

Study design

Prospective, nonrandomized, crossover design.

Study animals

Six healthy male Beagle dogs.

Methods

The dogs were anesthetized with propofol and isoflurane and mechanically ventilated under neuromuscular blockade. After instrumentation, they underwent a series of sequential, nonrandomized steps: Step 1: baseline data collection; Step 2: removal of 33 mL kg-1 of circulating blood volume; Step 3: blood re-transfusion; and Step 4: infusion of 20 mL kg-1 colloid solution. Following a 10-min stabilization period after each step, CO measurements were recorded using esophageal Doppler (EDCO), transesophageal echocardiography (TEECO), arterial pressure waveform analysis (APWACO), and electrical cardiometry (ECCO). Additionally, SDV, PVV, and SVV were recorded. Intermittent pulmonary artery thermodilution (iPATDCO) measurements were also recorded before, during, and after the PLRM maneuver. A successful FR diagnosis made using a specific test indicated that CO increased by more than 15% during the PLRM maneuver. Statistical analysis was performed using one-way analysis of variance for repeated measures with post hoc Tukey test, linear regression, Lin's concordance correlation coefficient (ρc), and Bland-Altman analysis. Statistical significance was set at p < 0.05.

Results

All techniques detected a reduction in CO (p < 0.001) during hemorrhage and an increase in CO after blood re-transfusion and colloid infusion (p < 0.001) compared with baseline. During hemorrhage, CO increases with the PLRM maneuver were as follows: 33% for iPATD (p < 0.001), 19% for EC (p = 0.03), 7% for APWA (p = 0.97), 39% for TEE (p < 0.001), and 17% for ED (p = 0.02). Concurrently, decreases in SVV, SDV, and PVV values (p < 0.001) were also observed. The percentage error for TEE, ED, and EC was less than 30% but exceeded 55% for APWA. While TEECO and ECCO slightly underestimated iPATDCO values, EDCO and APWACO significantly overestimated iPATDCO values. TEE and EC exhibited good and acceptable agreement with iPATD. However, CO measurements using all four techniques and iPATD did not differ before, during, and after PLRM at baseline, blood re-transfusion, and colloid infusion.

Conclusion and clinical relevance

iPATD, EC, TEE, and ED effectively assessed FR in hypovolemic dogs during the PLRM maneuver, while the performance of APWA was unacceptable and not recommended. SVV, SDV, and PVV could be used to monitor CO changes during PLRM and acute blood volume manipulations, suggesting their potential clinical utility.

Subclinical cardiac dysfunction may impact on fluid and vasopressor administration during early resuscitation of septic shock

BACKGROUND

According to the Surviving Sepsis Campaign (SSC) fluids and vasopressors are the mainstays of early resuscitation of septic shock while inotropes are indicated in case of tissue hypoperfusion refractory to fluids and vasopressors, suggesting severe cardiac dysfunction. However, septic cardiac disfunction encompasses a large spectrum of severities and may remain "subclinical" during early resuscitation. We hypothesized that "subclinical" cardiac dysfunction may nevertheless influence fluid and vasopressor administration during early resuscitation. We retrospectively reviewed prospectically collected data on fluids and vasoconstrictors administered outside the ICU in patients with septic shock resuscitated according to the SSC guidelines that had reached hemodynamic stability without the use of inotropes. All the patients were submitted to transpulmonary thermodilution (TPTD) hemodynamic monitoring at ICU entry. Subclinical cardiac dysfunction was defined as a TPTD-derived cardiac function index (CFI) ≤ 4.5 min-1.

RESULTS

At ICU admission, subclinical cardiac dysfunction was present in 17/40 patients (42%; CFI 3.6 ± 0.7 min-1 vs 6.6 ± 1.9 min-1; p < 0.01). Compared with patients with normal CFI, these patients had been resuscitate with more fluids (crystalloids 57 ± 10 vs 47 ± 9 ml/kg PBW; p < 0.01) and vasopressors (norepinephrine 0.65 ± 0.25 vs 0.43 ± 0.29 mcg/kg/min; p < 0.05). At ICU admission these patients had lower cardiac index (2.2 ± 0.6 vs 3.6 ± 0.9 L/min/m2, p < 0.01) and higher systemic vascular resistances (2721 ± 860 vs 1532 ± 480 dyn*s*cm-5/m2, p < 0.01).

CONCLUSIONS

In patients with septic shock resuscitated according to the SSC, we found that subclinical cardiac dysfunction may influence the approach to fluids and vasopressor administration during early resuscitation. Our data support the implementation of early, bedside assessment of cardiac function during early resuscitation of septic shock.

Prehospital pulse pressure and mortality of septic shock patients cared for by a mobile intensive care unit

BACKGROUND

Septic shock medical treatment relies on a bundle of care including antibiotic therapy and hemodynamic optimisation. Hemodynamic optimisation consists of fluid expansion and norepinephrine administration aiming to optimise cardiac output to reach a mean arterial pressure of 65mmHg. In the prehospital setting, direct cardiac output assessment is difficult because of the lack of invasive and non-invasive devices. This study aims to assess the relationship between 30-day mortality and (i) initial pulse pressure (iPP) as (ii) pulse pressure variation (dPP) during the prehospital stage among patients cared for SS by a prehospital mobile intensive care unit (MICU).

METHODS

From May 09th, 2016 to December 02nd, 2021, septic shock patients requiring MICU intervention were retrospectively analysed. iPP was calculated as the difference between systolic blood pressure (SBP) and diastolic blood pressure (DBP) at the first contact between the patient and the MICU team prior to any treatment and, dPP as the difference between the final PP (the difference between SBP and DBP at the end of the prehospital stage) and iPP divided by prehospital duration. To consider cofounders, the propensity score method was used to assess the relationship between (i) iPP < 40mmHg, (ii) positive dPP and 30-day mortality.

RESULTS

Among the 530 patients analysed, pulmonary, digestive, and urinary infections were suspected among 43%, 25% and 17% patients, respectively. The 30-day overall mortality rate reached 31%. Cox regression analysis showed an association between 30-day mortality and (i) iPP < 40mmHg; aHR of 1.61 [1.03-2.51], and (ii) a positive dPP; aHR of 0.56 [0.36-0.88].

CONCLUSION

The current study reports an association between 30-day mortality rate and iPP < 40mmHg and a positive dPP among septic shock patients cared for by a prehospital MICU. A negative dPP could be helpful to identify septic shock with higher risk of poor outcome despite prehospital hemodynamic optimization.

Impact of initial fluid resuscitation volume on clinical outcomes in patients with heart failure and septic shock

Background

Fluid resuscitation is a key treatment for sepsis, but limited data exists in patients with existing heart failure (HF) and septic shock. The objective of this study was to determine the impact of initial fluid resuscitation volume on outcomes in HF patients with reduced or mildly reduced left ventricular ejection fraction (LVEF) with septic shock.

Methods

This multicenter, retrospective, cohort study included patients with known HF (LVEF ≤50%) presenting with septic shock. Patients were divided into two groups based on the volume of fluid resuscitation in the first 6 h; <30 mL/kg or ≥30 mL/kg. The primary outcome was a composite of in-hospital mortality or renal replacement therapy (RRT) within 7 days. Secondary outcomes included acute kidney injury (AKI), initiation of mechanical ventilation, and length of stay (LOS). All related data were collected and compared between the two groups. A generalized logistic mixed model was used to assess the association between fluid groups and the primary outcome while adjusting for baseline LVEF, Acute Physiology and Chronic Health Evaluation (APACHE) II score, inappropriate empiric antibiotics, and receipt of corticosteroids.

Results

One hundred and fifty-four patients were included (93 patients in <30 mL/kg group and 61 patients in ≥30 mL/kg group). The median weight-based volume in the first 6 h was 17.7 (12.2-23.0) mL/kg in the <30 mL/kg group vs. 40.5 (34.2-53.1) mL/kg in the ≥30 mL/kg group (P <0.01). No statistical difference was detected in the composite of in-hospital mortality or RRT between the <30 mL/kg group compared to the ≥30 mL/kg group (55.9% vs. 45.9%, P=0.25), respectively. The <30 mL/kg group had a higher incidence of AKI, mechanical ventilation, and longer hospital LOS.

Conclusions

In patients with known reduced or mildly reduced LVEF presenting with septic shock, no difference was detected for in-hospital mortality or RRT in patients who received ≥30 mL/kg of resuscitation fluid compared to less fluid, although this study was underpowered to detect a difference. Importantly, ≥30 mL/kg fluid did not result in a higher need for mechanical ventilation.

Monitoring Macro- and Microcirculation in the Critically Ill: A Narrative Review

Circulatory shock is a common and important diagnosis in the critical care environment. Hemodynamic monitoring is quintessential in the management of shock. The currently used hemodynamic monitoring devices not only measure cardiac output but also provide data related to the prediction of fluid responsiveness, extravascular lung water, and also pulmonary vascular permeability. Additionally, these devices are minimally invasive and associated with fewer complications. The area of hemodynamic monitoring is progressively evolving with a trend toward the use of minimally invasive devices in this area. The critical care physician should be well-versed with current hemodynamic monitoring limitations and stay updated with the upcoming advances in this field so that optimal therapy can be delivered to patients in circulatory shock.

Fluid Responsiveness in Critically Ill Patients Using Carotid Peak Systolic Velocity Variability: A New Frontier

Background and objectives A fluid responder is a patient who can increase his stroke volume/ cardiac output by more than 10%-15% after a fluid bolus. Left ventricular outflow tract (LVOT) velocity time integral (VTI) variability is widely used as an adynamic parameter of fluid responsiveness, but a transthoracic echo view of LVOT VTI is often time-consuming and, at times, difficult to achieve. So, in the quest for another parameter that might equally be a good surrogate marker of stroke volume variation, carotid peak systolic velocity (CPSV) variation has been studied. The objective was to assess CPSV variation in patients who are already fluid responders. Methods The sample size was calculated considering a minimum correlation coefficient of 0.5. Adult patients in whom the physician wanted to give a fluid bolus and whose average LVOT VTI was more than 15% over 3 respiratory cycles were included in the study. Demographic variables, along with hemodynamic parameters such as heart rate, blood pressure, the need for vasopressors, mode of breathing (spontaneous or mechanical ventilation), and CPSV variation,were noted and averaged over three respiratory cycles. Fluid bolus (Plasmalyte) 6 ml/kg bolus over 10-15 minutes. Post-fluid hemodynamic variables, along with averaged LVOT VTI over three respiratory cycles and averaged CPSV variation over three respiratory cycles, are noted. Results Thirty adult patients were evaluated in the study. In spontaneously breathing patients (n=12), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight was 14.1 ± 3.4 and 5.4 ± 2.6, respectively (p < 0.05). In mechanically ventilated patients (n=18), the average CPSV variation expressed as mean + standard deviation before and after fluid administration of 6ml/kg of ideal body weight fluid was 15 ± 5.3 and 6.5 ± 3.1, respectively (p <0.005). Overall, there was a statistically significant positive correlation between LVOT VTI variation and CPSV variation before fluid therapy (correlation coefficient 0.56 and p-value 0.001) and a statistically significant moderate positive correlation post-fluid therapy (correlation coefficient 0.37 and p-value 0.043). Conclusion We found a significant decrease in CPSV variation post-fluid administration in patients who are fluid responders, which mimics a decrease in stroke volume variation after fluid administration in patients who are fluid responsive.

Usefulness of the velocity-time integral of the left ventricular outflow tract variability index to predict fluid responsiveness in patients undergoing cardiac surgery

BACKGROUND

Haemodynamic monitoring of patients after cardiac surgery using echocardiographic evaluation of fluid responsiveness is both challenging and increasingly popular. We evaluated fluid responsiveness in the first hours after surgery by determining the variability of the velocity-time integral of the left ventricular outflow tract (VTI-LVOT).

METHODS

We conducted a cross-sectional study of 50 consecutive adult patients who underwent cardiac surgery and in whom it was possible to obtain VTI-LVOT measurements. We then determined the variability and correlations with our pulse pressure variation (PPV) measurements to predict fluid responsiveness.

RESULTS

A strong positive correlation was seen between the VTI-LVOT variability index absolute values and PPV for predicting fluid responsiveness in the first hours after cardiac surgery. We also found that the VTI-LVOT variability index has high specificity and a high positive likelihood ratio compared with the gold standard using a cut-off point of ≥ 12%.

CONCLUSIONS

The VTI-LVOT variability index is a valuable tool for determining fluid responsiveness during the first 6 postoperative hours in patients undergoing cardiac surgery.

New Insights into the Fluid Management in Patients with Septic Shock

The importance of fluid resuscitation therapy during the early stages of sepsis management is a well-established principle. Current Surviving Sepsis Campaign (SSC) guidelines recommend the early administration of intravenous crystalloid fluids for sepsis-related hypotension or hyperlactatemia due to tissue hypoperfusion, within the first 3 h of resuscitation and suggest using balanced solutions (BSs) instead of normal saline (NS) for the management of patients with sepsis or septic shock. Studies comparing BS versus NS administration in septic patients have demonstrated that BSs are associated with better outcomes including decreased mortality. After initial resuscitation, fluid administration has to be judicious in order to avoid fluid overload, which has been associated with increased mortality, prolonged mechanical ventilation, and worsening of acute kidney injury. The "one size fits all" approach may be "convenient" but it should be avoided. Personalized fluid management, based on patient-specific hemodynamic indices, provides the foundations for better patient outcomes in the future. Although there is a consensus on the need for adequate fluid therapy in sepsis, the type, the amount of administered fluids, and the ideal fluid resuscitation strategy remain elusive. Well-designed large randomized controlled trials are certainly needed to compare fluid choices specifically in the septic patient, as there is currently limited evidence of low quality. This review aims to summarize the physiologic principles and current scientific evidence regarding fluid management in patients with sepsis, as well as to provide a comprehensive overview of the latest data on the optimal fluid administration strategy in sepsis.

Mock circulatory loop generated database for dynamic characterization of pressure-based cardiac output monitoring systems

Pulse contour cardiac output monitoring systems allow real-time and continuous estimation of hemodynamic variables such as cardiac output (CO) and stroke volume variation (SVV) by analysis of arterial blood pressure waveforms. However, evaluating the performance of CO monitoring systems to measure the small variations in these variables sometimes used to guide fluid therapy is a challenge due to limitations in clinical reference methods. We developed a non-clinical database as a tool for assessing the dynamic attributes of pressure-based CO monitoring systems, including CO response time and CO and SVV resolutions. We developed a mock circulation loop (MCL) that can simulate rapid changes in different parameters, such as CO and SVV. The MCL was configured to simulate three different states (normovolemic, cardiogenic shock, and hyperdynamic) representing a range of flow and pressure conditions. For each state, we simulated stepwise changes in the MCL flow and collected datasets for characterizing pressure-based CO systems. Nine datasets were generated that contain hours of peripheral pressure, central flow and pressure waveforms. The MCL-generated database is provided open access as a tool for evaluating dynamic characteristics of pressure-based CO algorithms and systems in detecting variations in CO and SVV indices. In an example application of the database, a CO response time of 10 s, CO and SVV resolutions with lower and upper limits of (-9.1%, 8.4%) and (-5.0%, 3.8%), respectively, were determined for a pressure-based CO benchtop system. This tool will support a more comprehensive assessment of pressure-based CO monitoring systems and algorithms.

Fluid management in septic patients with pulmonary hypertension, review of the literature

The management of sepsis in patients with pulmonary hypertension (PH) is challenging due to significant conflicting goals of management and complex hemodynamics. As PH progresses, the ability of right heart to perfuse lungs at a normal central venous pressure (CVP) is impaired. Elevated pulmonary vascular pressure, due to pulmonary vasoconstriction and vascular remodeling, opposes blood flow through lungs thus limiting the ability of right ventricle (RV) to increase cardiac output (CO) and maintain adequate oxygen delivery to tissue. In sepsis without PH, avoidance of volume depletion with intravascular volume replacement, followed by vasopressor therapy if hypoperfusion persists, remains the cornerstone of therapy. Intravenous fluid (IVF) resuscitation based on individualized hemodynamic assessment can help improve the prognosis of critically ill patients. This is accomplished by optimizing CO by maintaining adequate preload, afterload and contractility. Particular challenges in patients with PH include RV failure as a result of pressure and volume overload, gas exchange abnormalities, and managing IVF and diuretic use. Suggested approaches to remedy these difficulties include early recognition of symptoms associated with pressure and volume overload, intravascular volume management strategies and serial lab monitoring to assess electrolytes and renal function.

Perioperative Fluid Management and Volume Assessment

Fluid therapy is an integral component of perioperative care and helps maintain or restore effective circulating blood volume. The principal goal of fluid management is to optimize cardiac preload, maximize stroke volume, and maintain adequate organ perfusion. Accurate assessment of volume status and volume responsiveness is necessary for appropriate and judicious utilization of fluid therapy. To accomplish this, static and dynamic indicators of fluid responsiveness have been widely studied. This review discusses the overarching goals of perioperative fluid management, reviews the physiology and parameters used to assess fluid responsiveness, and provides evidence-based recommendations on intraoperative fluid management.

Photoplethysmography waveform analysis for classification of vascular tone and arterial blood pressure: Study based on neural networks

BACKGROUND

To test whether a Shallow Neural Network (S-NN) can detect and classify vascular tone dependent changes in arterial blood pressure (ABP) by advanced photopletysmographic (PPG) waveform analysis.

METHODS

PPG and invasive ABP signals were recorded in 26 patients undergoing scheduled general surgery. We studied the occurrence of episodes of hypertension (systolic arterial pressure (SAP) >140 mmHg), normotension and hypotension (SAP < 90 mmHg). Vascular tone according to PPG was classified in two ways: 1) By visual inspection of changes in PPG waveform amplitude and dichrotic notch position; where Classes I-II represent vasoconstriction (notch placed >50% of PPG amplitude in small amplitude waves), Class III normal vascular tone (notch placed between 20-50% of PPG amplitude in normal waves) and Classes IV-V-VI vasodilation (notch <20% of PPG amplitude in large waves). 2) By an automated analysis, using S-NN trained and validated system that combines seven PPG derived parameters.

RESULTS

The visual assessment was precise in detecting hypotension (sensitivity 91%, specificity 86% and accuracy 88%) and hypertension (sensitivity 93%, specificity 88% and accuracy 90%). Normotension presented as a visual Class III (III-III) (median and 1st-3rd quartiles), hypotension as a Class V (IV-VI) and hypertension as a Class II (I-III); all p < .0001. The automated S-NN performed well in classifying ABP conditions. The percentage of data with correct classification by S-ANN was 83% for normotension, 94% for hypotension, and 90% for hypertension.

CONCLUSIONS

Changes in ABP were correctly classified automatically by S-NN analysis of the PPG waveform contour.

Does tidal volume challenge improve the feasibility of pulse pressure variation in patients mechanically ventilated at low tidal volumes? A systematic review and meta-analysis

BACKGROUND

Pulse pressure variation (PPV) has been widely used in hemodynamic assessment. Nevertheless, PPV is limited in low tidal volume ventilation. We conducted this systematic review and meta-analysis to evaluate whether the tidal volume challenge (TVC) could improve the feasibility of PPV in patients ventilated at low tidal volumes.

METHODS

PubMed, Embase and Cochrane Library inception to October 2022 were screened for diagnostic researches relevant to the predictability of PPV change after TVC in low tidal volume ventilatory patients. Summary receiving operating characteristic curve (SROC), pooled sensitivity and specificity were calculated. Subgroup analyses were conducted for possible influential factors of TVC.

RESULTS

Ten studies with a total of 429 patients and 457 measurements were included for analysis. The predictive performance of PPV was significantly lower than PPV change after TVC in low tidal volume, with mean area under the receiving operating characteristic curve (AUROC) of 0.69 ± 0.13 versus 0.89 ± 0.10. The SROC of PPV change yielded an area under the curve of 0.96 (95% CI 0.94, 0.97), with overall pooled sensitivity and specificity of 0.92 (95% CI 0.83, 0.96) and 0.88 (95% CI 0.76, 0.94). Mean and median cutoff value of the absolute change of PPV (△PPV) were 2.4% and 2%, and that of the percentage change of PPV (△PPV%) were 25% and 22.5%. SROC of PPV change in ICU group, supine or semi-recumbent position group, lung compliance less than 30 cm H₂O group, moderate positive end-expiratory pressure (PEEP) group and measurements devices without transpulmonary thermodilution group yielded 0.95 (95%0.93, 0.97), 0.95 (95% CI 0.92, 0.96), 0.96 (95% CI 0.94, 0.97), 0.95 (95% CI 0.93, 0.97) and 0.94 (95% CI 0.92, 0.96) separately. The lowest AUROCs of PPV change were 0.59 (95% CI 0.31, 0.88) in prone position and 0.73 (95% CI 0.60, 0.84) in patients with spontaneous breathing activity.

CONCLUSIONS

TVC is capable to help PPV overcome limitations in low tidal volume ventilation, wherever in ICU or surgery. The accuracy of TVC is not influenced by reduced lung compliance, moderate PEEP and measurement tools, but TVC should be cautious applied in prone position and patients with spontaneous breathing activity. Trial registration PROSPERO (CRD42022368496). Registered on 30 October 2022.

Lung Ultrasound and Caval Indices to Assess Volume Status in Maintenance Hemodialysis Patients

Background: Volume overload is common in end stage kidney disease (ESKD) and dialysis patients. Hence, the need for objective tools to detect such volume excess. Point of care ultrasound (POCUS) is a goal-directed, bedside examination to answer such a specific diagnostic question. Methods: One hundred Iraqi adult hemodialysis patients were recruited from February 1 to May 31, 2022. Primary clinical, dialysis data, and prescriptions were recorded. A nephrologist performed a POCUS examination after the last dialysis session of the week. In addition, an ultrasound examination of the chest was performed to detect B-lines and pleural effusion. Caval parameters included inferior vena cava (IVC) diameter and collapsibility index. Results: The mean age of the study group was 51.48 ± 14.6 years, with 53% males. The mean interdialytic weight gain was 2.74 ± 1.15 Kg. Lower limb edema and pleural effusion were present in 33% and 27%, respectively. Forty-seven percent of patients had >3 B-lines on lung ultrasound with a range of 12. Forty-three percent of patients had an IVC diameter of >2 cm, and 93% had <50% IVC collapsibility. In total, 97% of patients had evidence of excess volume by ultrasound criteria. IVC collapsibility index was the most prevalent sign of excess volume (93%). Patients without lower limb edema and pleural effusion had positive B-lines in 38.8% and 38.3%, an IVC diameter >2 cm in 46.2% and 38.3%, and IVC collapsibility <50% in 89.5% and 95.8% respectively. Conclusion: Iraqi maintenance hemodialysis patients are volume overloaded, which warrants proper intervention for detection and dialysis management. POCUS is a useful and easily performed technique to assess the volume status.

The Use of Vigileo® Monitor in a Parturient With Severe Mitral Valve Stenosis and Severe Pulmonary Hypertension Undergoing Cesarean Section Under General Anesthesia: A Case Report and Literature Review

We report a case of a 35-year-old pregnant female of Afghan origin who was admitted to the intensive care unit (ICU) because of pulmonary edema development when she was in the 30th week of gestation. During the bedside examination, the transthoracic echocardiogram (TTE) revealed severe mitral valve stenosis and pulmonary hypertension. The patient went into treatment with metoprolol for the control of tachycardia and furosemide for the prevention of fluid overload. During the 32nd week of gestation, the medical council decided on a cesarean section (CS) to be carried out under general anesthesia. The anesthesiologists decided to use the Vigileo monitor (Edwards Lifesciences, Irvine, CA, USA) as it is vitally important to approach fluid administration as fluid management is challenging concerning the obstetric patient. Vigileo monitoring is based on the invasive measurement of cardiac output (CO), cardiac index (CI), stroke volume (SV), and stroke volume variation (SVV). Fluid resuscitation based on hemodynamic parameters is a key component of patient care, especially in scenarios such as cardiovascular disease. This is the first case report where a Vigileo monitor was applied to a patient with severe mitral valve stenosis and severe pulmonary hypertension undergoing a cesarean section, which was accomplished without any complications. The patient was discharged from the hospital on the 12th postoperative day, hemodynamically stable. Each immigrant woman, regardless of her financial, social, cultural, or any other situation, has the fundamental right to receive complete perinatal healthcare. Nevertheless, the most recent statistical data show that those women's access to public healthcare is insufficient, leading to high rates of maternal mortality. The international medical community has to adapt to the new multicultural environment, and health services must be provided to this vulnerable population with the appropriate level of safety.

Fluid challenge in critically ill patients receiving haemodynamic monitoring: a systematic review and comparison of two decades

Introduction

Fluid challenges are widely adopted in critically ill patients to reverse haemodynamic instability. We reviewed the literature to appraise fluid challenge characteristics in intensive care unit (ICU) patients receiving haemodynamic monitoring and considered two decades: 2000–2010 and 2011–2021.

Methods

We assessed research studies and collected data regarding study setting, patient population, fluid challenge characteristics, and monitoring. MEDLINE, Embase, and Cochrane search engines were used. A fluid challenge was defined as an infusion of a definite quantity of fluid (expressed as a volume in mL or ml/kg) in a fixed time (expressed in minutes), whose outcome was defined as a change in predefined haemodynamic variables above a predetermined threshold.

Results

We included 124 studies, 32 (25.8%) published in 2000–2010 and 92 (74.2%) in 2011–2021, overall enrolling 6,086 patients, who presented sepsis/septic shock in 50.6% of cases. The fluid challenge usually consisted of 500 mL (76.6%) of crystalloids (56.6%) infused with a rate of 25 mL/min. Fluid responsiveness was usually defined by a cardiac output/index (CO/CI) increase ≥ 15% (70.9%). The infusion time was quicker (15 min vs 30 min), and crystalloids were more frequent in the 2011–2021 compared to the 2000–2010 period.

Conclusions

In the literature, fluid challenges are usually performed by infusing 500 mL of crystalloids bolus in less than 20 min. A positive fluid challenge response, reported in 52% of ICU patients, is generally defined by a CO/CI increase ≥ 15%. Compared to the 2000–2010 decade, in 2011–2021 the infusion time of the fluid challenge was shorter, and crystalloids were more frequently used.

Pathophysiology of fluid administration in critically ill patients

Fluid administration is a cornerstone of treatment of critically ill patients. The aim of this review is to reappraise the pathophysiology of fluid therapy, considering the mechanisms related to the interplay of flow and pressure variables, the systemic response to the shock syndrome, the effects of different types of fluids administered and the concept of preload dependency responsiveness. In this context, the relationship between preload, stroke volume (SV) and fluid administration is that the volume infused has to be large enough to increase the driving pressure for venous return, and that the resulting increase in end-diastolic volume produces an increase in SV only if both ventricles are operating on the steep part of the curve. As a consequence, fluids should be given as drugs and, accordingly, the dose and the rate of administration impact on the final outcome. Titrating fluid therapy in terms of overall volume infused but also considering the type of fluid used is a key component of fluid resuscitation. A single, reliable, and feasible physiological or biochemical parameter to define the balance between the changes in SV and oxygen delivery (i.e., coupling "macro" and "micro" circulation) is still not available, making the diagnosis of acute circulatory dysfunction primarily clinical.

Intravenous fluid therapy in sepsis

Sepsis is the dysregulated immune response to severe infection that is common and lethal among critically ill patients. Fluid administration is a common treatment for hypotension and shock in early sepsis. Fluid therapy can also cause edema and organ dysfunction. Research on the best treatment strategies for sepsis has provided insights on the optimal timing, dose, and type of fluid to treat patients with sepsis. Initial research on early goal-directed therapy for sepsis included an initial bolus of 30 ml/kg of fluid, but more recent research has supported use of smaller volumes. After initial fluid resuscitation, minimizing additional fluid administration may be beneficial, but no single measure has been established as the best method to guide ongoing fluid management in sepsis. Dynamic measures of "fluid responsiveness" can predict which patients will experience an increase in cardiac output from a fluid bolus. Use of such a measure in clinical care remains limited by applicability to patient populations and uncertainty regarding the effect on clinical outcomes. Recent research informs the effect of fluid composition on outcomes for patients with sepsis. Current data support the use of balanced crystalloids, rather than saline, and the use of crystalloids, rather than semisynthetic colloids. The role for albumin administration in sepsis remains uncertain. Future research should focus on determining the optimal volume of fluid during sepsis resuscitation, the effectiveness of measures of "fluid responsiveness" in improving outcomes, the optimal composition of crystalloid solutions, the role of albumin, and the effects of "deresuscitation" after septic shock.

Comparison of inferior vena cava collapsibility and central venous pressure in assessing volume status in shocked patients

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An accurate diagnosis of shock state can be challenging, particularly in low-income countries, such as African countries, because physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap.

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Low-income countries therefore require easy and noninvasive methods, such as ultrasound devices.

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This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the management of shocked patients.

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We discovered that the inferior vena cava collapsibility index (IVC-ci) could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.

Introduction

Determination of intravascular volume status in patients admitted to the emergency centre is critical. Physical signs of hypovolaemic, distributive, cardiogenic, and obstructive shock frequently overlap, making an accurate diagnosis of shock state difficult. This is problematic because fluid loading is considered the first step in haemodynamically unstable patients’ resuscitation. Yet, multiple studies have shown that only approximately 50% of haemodynamically unstable patients in the intensive care unit and operating theatre respond to a fluid challenge. This study aims to provide an accurate estimation of intravascular volume status using bedside noninvasive methods as an essential part of the assessment of volume status in shocked patients.

Methodology

This is a cross-sectional analytical study conducted on 102 shocked patients presented to the emergency centre. IV fluid boluses were standardized to be administered at 500 mL every 30 min over 120 min, as clinically indicated. Concurrent measurements of inferior vena cava collapsibility index (IVC-ci) were performed shortly before the initiation of IV bolus (i.e., time 0), and then at 30, 90, and 120 min, we measured both venous collapsibility index (CI) and central venous pressure (CVP). At each session, we recorded patient demographics, fluid responsiveness, and vital sign assessments.

Results

We discovered that IVC-ci at cut-off point 40 has a sensitivity of 93.3% and specificity of 70.7% with an AUC of 0.908 and a good 95% CI (0.84–0.975), implying that IVC-ci of 40% or higher can indicate fluid responsiveness in shocked patients. CVP, despite having a good sensitivity of 88.6%, high specificity of 100%, and a significant p-value, is not a reliable detector of fluid responsiveness due to its small AUC value and low 95% CI.

Conclusion

IVC-ci could be a good tool with moderate reliability for detecting fluid responsiveness because it is a less invasive and fast method.