Does the central venous pressure predict fluid responsiveness? An updated meta-analysis and a plea for some common sense. Crit Care Med. 2013;41:1774-1781. [PMID: 23774337 DOI: 10.1097/ccm.0b013e31828a25fd]

Knowledge and Awareness of Volume Assessment Among Emergency and Intensive Care Physicians in Saudi Arabia

BACKGROUND

Fluid volume measurement in the emergency department and intensive care unit (ICU) is critical for patient care. This study aimed to assess the knowledge of volume assessment among emergency medicine (EM) and ICU physicians in Saudi Arabia.

MATERIALS AND METHODS

A cross-sectional study was conducted among EM and ICU physicians using an online questionnaire. Data were collected on participants' demographics, work-related information, confidence in volume assessment, use of point-of-care ultrasonography, and knowledge and practices of volume assessment.

RESULTS

Of the 114 physicians surveyed, 92 (80.7%) were aged 25-35 years, 65 (57%) were male, 70 (61.4%) were EM physicians, and 68 (59.6%) had fewer than five years of practice. ICU physicians demonstrated significantly higher knowledge that, in mechanically ventilated patients, a distensibility index of >18% indicates fluid responsiveness. In contrast, EM physicians had a higher proportion of correct responses regarding the indications for using Swan-Ganz catheters. The most commonly used method for volume assessment was physical examination (83, 72.8%), and the most frequently used laboratory biomarker was serum lactate (65, 57%). The majority (85, 74.6%) used focused cardiac assessments, including evaluation of the inferior vena cava, for volume assessment. ICU physicians reported significantly higher use of Doppler ultrasound for volume assessment. Only 17 (14.9%) physicians demonstrated a good level of knowledge of volume assessment, with no significant associations found between knowledge level and participants' demographics, work experience, or confidence in volume assessment.

CONCLUSIONS

A poor understanding of fluid volume assessment was observed among EM and ICU physicians in Saudi Arabia. Training on the principles of volume assessment is needed.

Current Concepts in Fluid Resuscitation and Vasopressor Use in Cirrhosis

Critically ill patients with cirrhosis and liver failure do not uncommonly have hypotension due to multifactorial reasons, which include a hyperdynamic state with increased cardiac index (CI), low systemic vascular resistance (SVR) due to portal hypertension, following the use of beta-blocker or diuretic therapy, and severe sepsis. These changes are mediated by microvascular alterations in the liver, systemic inflammation, activation of renin-angiotensin-aldosterone system, and vasodilatation due to endothelial dysfunction. Haemodynamic assessment includes measuring inferior vena cava indices, cardiac output (CO), and SVR using point-of-care ultrasound (POCUS), arterial waveform analysis, pulmonary artery pressures, and lactate clearance to guide fluid resuscitation. Fluid responsiveness reflects the ability of fluid bolus to increase the CO and is assessed effectively by POCUS, passive leg raises manoeuvre, and dynamic tests such as pulse pressure and stroke volume variation in spontaneously breathing and mechanically ventilated patients. Albumin has pleiotropic benefits through anti-inflammatory properties besides its standard action on oncotic pressure and volume expansion in patients with cirrhosis but has the potential for precipitating pulmonary oedema. In conclusion, fluid therapy in critically ill patients with liver disease is a complex and dynamic process that requires individualized management protocols to optimize patient outcomes.

Haemodynamic management of septic shock

Septic shock is a significant challenge in the management of patients with burns and traumatic injuries when complicated by infection, necessitating prompt and effective haemodynamic support. This review provides a comprehensive overview of current strategies for vasopressor and fluid management in septic shock, with the aim to optimize patient outcomes. With regard to vasopressor management, we elaborate on the pharmacologic profiles and clinical applications of catecholamines, vasopressin derivatives, angiotensin II, and other vasoactive agents. Noradrenaline remains central to septic shock management. The addition of vasopressin, when sequentially added to noradrenaline, offers a non-catecholaminergic vasoactive effect with some clinical benefits and risks of adverse effects. Emerging agents such as angiotensin II and hydroxocobalamin are highlighted for their roles in catecholamine-resistant vasodilatory shock. Next, for fluid management, crystalloids are currently preferred for initial resuscitation, with balanced crystalloids showing benefits over saline. The application of albumin in septic shock warrants further research. High-quality evidence does not support large-volume fluid resuscitation, and an individualized strategy based on haemodynamic parameters, including lactate clearance and capillary refill time, is recommended. The existing knowledge suggests that early vasopressor initiation, particularly noradrenaline, may be critical in cases where fluid resuscitation takes inadequate effect. Management of refractory septic shock remains challenging, with novel agents like angiotensin II and methylene blue showing potential in recent studies. In conclusion, Further research is needed to optimize haemodynamic management of septic shock, particularly in developing novel vasopressor usage and fluid management approaches.

Demystifying Volume Status: An Ultrasound-Guided Physiologic Framework

TOPIC IMPORTANCE

Accurate assessment of a patient's volume status is crucial in many conditions, informing decisions on fluid prescribing, vasoactive agents, and decongestive therapies. Determining a patient's volume status is challenging because of limitations in examination and investigations and the complexities of fluid homeostasis in disease states. Point-of-care ultrasound (POCUS) is useful in assessing hemodynamic parameters related to volume status, fluid responsiveness, and fluid tolerance. It requires understanding several physiologic concepts to interpret and integrate POCUS findings accurately into volume-related clinical decision-making.

REVIEW FINDINGS

The following concepts serve as a scaffold for a comprehensive volume status assessment: central venous pressure, right-sided heart function, left-sided heart assessment, extravascular volume, and venous congestion. POCUS allows us access to these hemodynamic and structural data points as an extension and refinement of the physical examination. Often, multiple POCUS applications are used, and findings must be integrated with the rest of the clinical evaluation. We illustrate this using 3 common scenarios: hypotension, hypoxia, and acute kidney injury. Clinicians must be aware of the strengths and weaknesses of findings in different physiologic states and the potential pitfalls of image acquisition and interpretation. Further studies are necessary to determine the benefits and clinical outcomes of a POCUS-directed volume status assessment.

SUMMARY

Volume status assessment is ubiquitous, yet is challenging to perform. This review summarizes foundational physiologic concepts relevant to volume status evaluation and highlights how multiorgan POCUS elucidates hemodynamic parameters that can be combined with the conventional clinical assessment to make fluid-related decisions.

Perioperative Acute Kidney Injury: Diagnosis, Prediction, Prevention, and Treatment

In this review, the authors define acute kidney injury in the perioperative setting, describe the epidemiologic burden, discuss procedure-specific risk factors, detail principles of management, and highlight areas of ongoing controversy and research.

Predictive value of trendelenburg position and carotid ultrasound for fluid responsiveness in patients on VV-ECMO with acute respiratory distress syndrome in the prone position

Fluid administration is widely used to treat hypotension in patients undergoing veno-venous extracorporeal membrane oxygenation (VV-ECMO). However, excessive fluid administration may lead to fluid overload can aggravate acute respiratory distress syndrome (ARDS) and increase patient mortality, predicting fluid responsiveness is of great significance for VV-ECMO patients. This prospective single-center study was conducted in a medical intensive care unit (ICU) and finally included 51 VV-ECMO patients with ARDS in the prone position (PP). Stroke volume index variation (ΔSVI), pulse pressure variation (PPV), stroke volume variation (SVV), baseline carotid corrected flow time (FTcBaseline), and respirophasic variation in carotid artery blood flow peak velocity (ΔVpeakCA) were taken before and after the Trendelenburg position or volume expansion. Fluid responsiveness was defined as a 15% or more increase in stroke volume index as assessed by transthoracic echocardiography after the volume expansion (VE). In our study, 33 patients (64.7%) were identified as fluid responders. Stroke volume index variation induced by the Trendelenburg position (ΔSVITrend), FTcBaseline, and ΔVpeakCA demonstrated superior predictive performance of fluid responsiveness. ΔSVITrend had an AUC of 0.89 (95% CI, 0.80-0.98) with an optimal threshold of 14.5% (95% CI, 12.5-21.5%), with the sensitivity and specificity were 82% (95% CI, 66-91%) and 83% (95% CI, 61-94%). FTcBaseline had an AUC of 0.87 (95% CI, 0.76-0.98) with an optimal threshold of 332ms (95% CI, 318-335ms), the sensitivity and specificity were 85% (95% CI, 69-93%) and 83% (95% CI, 61-94%), respectively. ΔVpeakCA showed an AUC of 0.83 (95% CI, 72-95), with a 10% optimal threshold (95% CI, 9-13%), sensitivity was 82% (95% CI, 66-91%) and specificity 78% (95% CI, 55-91%). ΔSVITrend, FTcBaseline and ΔVpeakCA could effectively predict fluid responsiveness in VV-ECMO patients with ARDS in the PP. Compared to ΔSVITrend and ΔVpeakCA, FTcBaseline is easier and more direct to acquire, and it does not require Trendelenburg position or VE, making it a more accessible and efficient option for assessing fluid responsiveness.

Navigating Heart-Lung Interactions in Mechanical Ventilation: Pathophysiology, Diagnosis, and Advanced Management Strategies in Acute Respiratory Distress Syndrome and Beyond

Patients in critical condition who require mechanical ventilation experience intricate interactions between their respiratory and cardiovascular systems. These complex interactions are crucial for clinicians to understand as they can significantly influence therapeutic decisions and patient outcomes. A deep understanding of heart-lung interactions is essential, particularly under the stress of mechanical ventilation, where the right ventricle plays a pivotal role and often becomes a primary concern. Positive pressure ventilation, commonly used in mechanical ventilation, impacts right and left ventricular pre- and afterload as well as ventricular interplay. The right ventricle is especially susceptible to these changes, and its function can be critically affected, leading to complications such as right heart failure. Clinicians must be adept at recognizing and managing these interactions to optimize patient care. This perspective will analyze this matter comprehensively, covering the pathophysiology of these interactions, the monitoring of heart-lung dynamics using the latest methods (including ECHO), and management and treatment strategies for related conditions. In particular, the analysis will delve into the efficacy and limitations of various treatment modalities, including pharmaceutical interventions, nuanced ventilator management strategies, and advanced devices such as extracorporeal membrane oxygenation (ECMO). Each approach will be examined for its impact on optimizing right ventricular function, mitigating complications, and ultimately improving patient outcomes in the context of mechanical ventilation.

Changes in portal pulsatility index induced by a fluid challenge in patients with haemodynamic instability and systemic venous congestion: a prospective cohort study

BACKGROUND

It is uncertain whether fluid administration can improve patients with systemic venous congestion and haemodynamic instability. This study aimed to describe the changes in systemic venous congestion and peripheral perfusion parameters induced by a fluid challenge in these patients, and to analyse the influence of the fluid responsiveness status on these changes.

METHODS

The study is a single-centre prospective cohort study of 36 critically ill ICU patients with haemodynamic instability and a maximum vena cava diameter ≥ 20 mm. Changes in cardiac index during a fluid challenge (4 mL/kg of lactated Ringer's solution during 5 min) assessed by pulse contour analysis, central venous pressure, ultrasound systemic congestion parameters (portal venous flow pulsatility index, supra hepatic and intrarenal venous Doppler), and peripheral perfusion parameters (capillary refill time and peripheral perfusion index) were assessed in the overall population. All these data were compared between patients presenting a cardiac index increase > 10% during the fluid challenge (fluid responders) and the others (fluid non-responders).

RESULTS

Twenty-eight (78%) patients were admitted for postoperative care following cardiac surgery; their mean ± SD left ventricular ejection fraction was 42 ± 9% and right ventricular dysfunction was found in at least 61% of the patients. The mean ± SD SOFA score was 9 ± 3. Thirteen (36%) patients were fluid responders. The fluid challenge administration induced a significant increase in portal pulsatility index, VExUS score, and central venous pressure without significant difference of these changes between fluid responders and non-responders. No significant change in perfusion parameters was observed.

CONCLUSION

Fluid administration in patients with haemodynamic instability and systemic venous congestion worsens venous congestion regardless of the fluid responsiveness status, without improving perfusion parameters.

[Bedside imaging]

Sonography, in particular echocardiography, is essential in the assessment of volume status and hemodynamics in critically ill patients. Examination of the left ventricle, in addition to assessing ventricular function, provides valuable information, including the "kissing papillary muscle sign," which may indicate fluid responsiveness. Examination of the right ventricle is also important because it is sensitive to both volume and pressure overload. Assessment of diastolic function and measurement of inferior vena cava width and variability provide clues to left and right ventricular preload, respectively. Measurement of stroke volume and cardiac output allows further assessment of hemodynamics and also permits determination of stroke volume variability.

[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.

Intraoperative central venous pressures related to early graft function in deceased donor kidney transplant recipients with low immunological risks

This study aims to analyze data from patients who received kidney transplantation from deceased donors to investigate the anesthetic factors influencing early and late graft outcomes, including the incidence of slow graft function (SGF), delayed graft function (DGF), and 3-year graft outcomes. We retrospectively analyzed 202 recipients who underwent deceased donor kidney transplantation from March 2010 to December 2020. Anesthetic monitoring data during the intraoperative period was analyzed at 5-minute intervals, and basic clinical parameters were evaluated. The mean recipient age was 46.6 ± 10.3 years, and the mean donor age was 41.7 ± 12.7 years. Anesthetic time averaged 285.8 ± 70.2 min, and operation time averaged 223.1 ± 44.0 min. The incidence of SGF was 11.8%, and the incidence of DGF was 3.9%. Mean central venous pressures (CVPs) were higher in recipients with SGF or DGF (11.7 mmHg) compared to those with immediate graft function (9.7 mmHg). Higher CVP was identified as an independent risk factor for SGF or DGF (odds ratio 1.219, p = 0.006). This study suggests that intraoperative monitoring of CVP is crucial for predicting short-term graft function in deceased donor kidney transplantation and should be managed to prevent excessive fluid intake.

Mistaken Identity: Misidentification of Other Vascular Structures as the Inferior Vena Cava and How to Avoid It

While point-of-care ultrasound (POCUS) of the inferior vena cava (IVC) is broadly perceived as having value in intravascular volume status assessment, this has not been borne out in large-scale meta-analyses containing heterogenous populations of acutely ill patients. While the limitations of IVC POCUS could be largely due to the complexity of the relationship between IVC appearance and volume status, another confounder not widely appreciated is the ease with which the aorta or right hepatic vein (RHV) can be mistaken for the IVC. While misidentification of the aorta as the IVC has been recognized elsewhere, misidentification of the RHV for the IVC has not and, in our experience, occurs frequently, even in the hands of experienced sonographers. We demonstrate how these errors occur and provide guidance on how to systematically avoid them.

Exploring the optimal range of central venous pressure in sepsis and septic shock patients: A retrospective study in 208 hospitals

BACKGROUND

The aim of this study was to investigate the optimal CVP range in sepsis and septic shock patients admitted to intensive care unit.

METHODS

We performed a retrospective study with adult sepsis patients with CVP records based on the eICU Collaborative Research Database. Multivariable logistic regression was performed to explore the associations between CVP level and hospital mortality. Non-linear correlations and optimal CVP range were explored using restricted cubic splines (RCS).

RESULTS

A total of 5302 sepsis patients were included in this study. Patients in 4-8 mmHg group owned the lowest odds ratio for raw hospital mortality (19.7%). The logistic regression analyses revealed that hospital death risk increased significantly when mean CVP level exceeds 12 mmHg compared to 4-8 mmHg level. U-shaped association of CVP with hospital mortality was revealed by RCS model in septic shock patients and the optimal range was 5.6-12 mmHg. While, there was a J-shaped trend for non-septic shock patients. For non-septic shock patients, patients had an increased risk of hospital death only if CVP exceeded 11 mmHg.

CONCLUSIONS

We observed U-shaped association between mean CVP level and hospital mortality in septic shock patients and J-shaped association in non-septic shock patients. This may imply that patients with different severity of sepsis have different CVP requirements. We need to monitor and manage CVP according to the circulatory status of the sepsis patient.

Predicting stroke volume variation using central venous pressure waveform: a deep learning approach

Objective. This study evaluated the predictive performance of a deep learning approach to predict stroke volume variation (SVV) from central venous pressure (CVP) waveforms.Approach. Long short-term memory (LSTM) and the feed-forward neural network were sequenced to predict SVV using CVP waveforms obtained from the VitalDB database, an open-source registry. The input for the LSTM consisted of 10 s CVP waveforms sampled at 2 s intervals throughout the anesthesia duration. Inputs of the feed-forward network were the outputs of LSTM and demographic data such as age, sex, weight, and height. The final output of the feed-forward network was the SVV. The performance of SVV predicted by the deep learning model was compared to SVV estimated derived from arterial pulse waveform analysis using a commercialized model, EV1000.Main results. The model hyperparameters consisted of 12 memory cells in the LSTM layer and 32 nodes in the hidden layer of the feed-forward network. A total of 224 cases comprising 1717 978 CVP waveforms and EV1000/SVV data were used to construct and test the deep learning models. The concordance correlation coefficient between estimated SVV from the deep learning model were 0.993 (95% confidence interval, 0.992-0.993) for SVV measured by EV1000.Significance. Using a deep learning approach, CVP waveforms can accurately approximate SVV values close to those estimated using commercial arterial pulse waveform analysis.

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 Pleth Variability Index as a Guide to Fluid Therapy in Dogs Undergoing General Anesthesia: A Preliminary Study

The aim of this prospective, randomized clinical trial was to evaluate the use of the pleth variability index (PVi) to guide the rate of intraoperative fluid therapy compared to a traditional fixed-fluid-rate approach in ASA 1-2 dogs undergoing surgery. Twenty-seven dogs met the inclusion criteria and were randomly assigned to the conventional fluid management group (CFM, n = 12) or the PVi-guided group (PVi, n = 15). The CFM group received a fixed rate of 5 mL kg-1 h-1 of crystalloid solution, while in the PVi group the rate was continuously adjusted based on the PVi: PVi < 14% = 3 mL kg-1 h-1; 14% ≤ PVi ≥ 20% = 10 mL kg-1 h-1; and PVi > 20% = 15 mL kg-1 h-1. Hypotension (MAP < 65 mmHg) in the CFM was treated with a maximum of two fluid boluses (5 mL kg-1 in 10 min) and in the case of no response, dobutamine (1-3 mcg kg-1 min-1) was administered. In the PVi group, the treatment of hypotension was similar, except when the PVi > 14%, when dobutamine was started directly. Total fluid volume was significantly lower in the PVI group (0.056 ± 0.027 mL kg-1 min-1) compared to the CFM group (0.132 ± 0.115 mL kg-1 min-1), and the incidence of hypotension was lower (p = 0.023) in the PVi group (0%) compared to the CFM group (41%). The mean arterial pressure (MAP) was significantly higher in the PVi group during surgery. Dobutamine was never administered in either group. Preliminary data suggest that the PVi may be considered as a potential target to guide fluid therapy in dogs; larger studies are needed, especially in cases of cardiovascular instability.

Intrarenal venous flow patterns - Guiding fluid management in sepsis with AKI: A case report

INTRODUCTION

Sepsis often leads to acute kidney injury (AKI), presenting significant challenges in fluid management. This study explores the potential of analyzing intrarenal venous flow (IRVF) patterns to guide tailored fluid therapy, aiming to improve patient outcomes.

PATIENT CONCERNS

A patient was admitted to the intensive care unit with symptoms of septic shock, including fever, severe hypotension, and altered mental status, secondary to a perforated ascending colon adenocarcinoma.

DIAGNOSIS

The patient was diagnosed with perforated ascending colon adenocarcinoma, septic shock, and AKI. Clinical findings included elevated inflammatory markers and impaired renal function.

INTERVENTIONS

The primary therapeutic interventions included surgical resection of the perforated colon, administration of broad-spectrum antibiotics, and fluid resuscitation. Fluid management was guided by continuous monitoring of IRVF, which facilitated precise adjustments to optimize fluid balance and renal perfusion.

OUTCOMES

By utilizing IRVF patterns to guide fluid therapy, the patient's circulatory status and renal function significantly improved. The individualized fluid management approach contributed to better stabilization of the patient's condition.

LESSONS

This case underscores the potential utility of IRVF patterns in guiding fluid management strategies for patients with sepsis and AKI. The main is the benefit of IRVF-guided fluid therapy in improving patient outcomes. Further research is warranted to validate the efficacy and safety of this approach, with the aim of enhancing clinical outcomes in critically ill patients.

Effects of dynamic versus static parameter-guided fluid resuscitation in patients with sepsis: A randomized controlled trial

Background

Fluid resuscitation is an essential component for sepsis treatment. Although several studies demonstrated that dynamic variables were more accurate than static variables for prediction of fluid responsiveness, fluid resuscitation guidance by dynamic variables is not standard for treatment. The objectives were to determine the effects of dynamic inferior vena cava (IVC)-guided versus (vs.) static central venous pressure (CVP)-guided fluid resuscitation in septic patients on mortality; and others, i.e., resuscitation targets, shock duration, fluid and vasopressor amount, invasive respiratory support, length of stay and adverse events.

Methods

A single-blind randomized controlled trial was conducted at Thammasat University Hospital between August 2016 and April 2020. Septic patients were stratified by acute physiologic and chronic health evaluation II (APACHE II) <25 or ≥25 and randomized by blocks of 2 and 4 to fluid resuscitation guidance by dynamic IVC or static CVP.

Results

Of 124 patients enrolled, 62 were randomized to each group, and one of each was excluded from mortality analysis. Baseline characteristics were comparable. The 30-day mortality rates between dynamic IVC vs. static CVP groups were not different (34.4% vs. 45.9%, p=0.196). Relative risk for 30-day mortality of dynamic IVC group was 0.8 (95%CI=0.5-1.2, p=0.201). Different outcomes were median (interquartile range) of shock duration (0.8 (0.4-1.6) vs. 1.5 (1.1-3.1) days, p=0.001) and norepinephrine (NE) dose (6.8 (3.9-17.8) vs. 16.1 (7.6-53.6) milligrams, p=0.008 and 0.1 (0.1-0.3) vs. 0.3 (0.1-0.8) milligram⋅kilogram -1, p=0.017). Others were not different.

Conclusions

Dynamic IVC-guided fluid resuscitation does not affect mortality of septic patients. However, this may reduce shock duration and NE dose, compared with static CVP guidance.

Accuracy of Noninvasive Blood Pressure Monitoring in Critically Ill Adults

Background: Blood pressure (BP) is routinely invasively monitored by an arterial catheter in the intensive care unit (ICU). However, the available data comparing the accuracy of noninvasive methods to arterial catheters for measuring BP in the ICU are limited by small numbers and diverse methodologies. Purpose: To determine agreement between invasive arterial blood pressure monitoring (IABP) and noninvasive blood pressure (NIBP) in critically ill patients. Methods: This was a single center, observational study of critical ill adults in a tertiary care facility evaluating agreement (≤10% difference) between simultaneously measured IABP and NIBP. We measured clinical features at time of BP measurement inclusive of patient demographics, laboratory data, severity of illness, specific interventions (mechanical ventilation and dialysis), and vasopressor dose to identify particular clinical scenarios in which measurement agreement is more or less likely. Results: Of the 1852 critically ill adults with simultaneous IABP and NIBP readings, there was a median difference of 6 mm Hg in mean arterial pressure (MAP), interquartile range (1-12), P < .01. A logistic regression analysis identified 5 independent predictors of measurement discrepancy: increasing doses of norepinephrine (adjusted odds ratio [aOR] 1.10 [95% confidence interval, CI 1.08-1.12] P = .03 for every change in 5 µg/min), lower MAP value (aOR 0.98 [0.98-0.99] P < .01 for every change in 1 mm Hg), higher body mass index (aOR 1.04 [1.01-1.09] P = .01 for an increase in 1), increased patient age (aOR 1.31 [1.30-1.37] P < .01 for every 10 years), and radial arterial line location (aOR 1.74 [1.16-2.47] P = .04). Conclusions: There was broad agreement between IABP and NIBP in critically ill patients over a range of BPs and severity of illness. Several variables are associated with measurement discrepancy; however, their predictive capacity is modest. This may guide future study into which patients may specifically benefit from an arterial catheter.

Point-of-care ultrasonography in cirrhosis-related acute kidney injury: How I do it

Discerning the etiology of acute kidney injury (AKI) in cirrhotic patients remains a formidable challenge due to diverse and overlapping causes. The conventional approach of empiric albumin administration for suspected volume depletion may inadvertently lead to fluid overload. In the recent past, point-of-care ultrasonography (POCUS) has emerged as a valuable adjunct to clinical assessment, offering advantages in terms of diagnostic accuracy, rapidity, cost-effectiveness, and patient satisfaction. This review provides insights into the strategic use of POCUS in evaluating cirrhotic patients with AKI. The review distinguishes basic and advanced POCUS, emphasizing a 5-point basic POCUS protocol for efficient assessment. This protocol includes evaluations of the kidneys and urinary bladder for obstructive nephropathy, lung ultrasound for detecting extravascular lung water, inferior vena cava (IVC) ultrasound for estimating right atrial pressure, internal jugular vein ultrasound as an alternative to IVC assessment, and focused cardiac ultrasound for assessing left ventricular (LV) systolic function and identifying potential causes of a plethoric IVC. Advanced POCUS delves into additional Doppler parameters, including stroke volume and cardiac output, LV filling pressures and venous congestion assessment to diagnose or prevent iatrogenic fluid overload. POCUS, when employed judiciously, enhances the diagnostic precision in evaluating AKI in cirrhotic patients, guiding appropriate therapeutic interventions, and minimizing the risk of fluid-related complications.

Predicting Fluid Responsiveness Using Carotid Ultrasound in Mechanically Ventilated Patients: A Systematic Review and Meta-Analysis of Diagnostic Test Accuracy Studies

BACKGROUND

A noninvasive and accurate method of determining fluid responsiveness in ventilated patients would help to mitigate unnecessary fluid administration. Although carotid ultrasound has been previously studied for this purpose, several studies have recently been published. We performed an updated systematic review and meta-analysis to evaluate the accuracy of carotid ultrasound as a tool to predict fluid responsiveness in ventilated patients.

METHODS

Studies eligible for review investigated the accuracy of carotid ultrasound parameters in predicting fluid responsiveness in ventilated patients, using sensitivity and specificity as markers of diagnostic accuracy (International Prospective Register of Systematic Reviews [PROSPERO] CRD42022380284). All included studies had to use an independent method of determining cardiac output and exclude spontaneously ventilated patients. Six bibliographic databases and 2 trial registries were searched. Medline, Embase, Emcare, APA PsycInfo, CINAHL, and the Cochrane Library were searched on November 4, 2022. Clinicaltrials.gov and Australian New Zealand Clinical Trials Registry were searched on February 24, 2023. Results were pooled, meta-analysis was conducted where possible, and hierarchical summary receiver operating characteristic models were used to compare carotid ultrasound parameters. Bias and evidence quality were assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) guidelines.

RESULTS

Thirteen prospective clinical studies were included (n = 648 patients), representing 677 deliveries of volume expansion, with 378 episodes of fluid responsiveness (58.3%). A meta-analysis of change in carotid Doppler peak velocity (∆CDPV) yielded a sensitivity of 0.79 (95% confidence interval [CI], 0.74-0.84) and a specificity of 0.85 (95% CI, 0.76-0.90). Risk of bias relating to recruitment methodology, the independence of index testing to reference standards and exclusionary clinical criteria were evaluated. Overall quality of evidence was low. Study design heterogeneity, including a lack of clear parameter cutoffs, limited the generalizability of our results.

CONCLUSIONS

In this meta-analysis, we found that existing literature supports the ability of carotid ultrasound to predict fluid responsiveness in mechanically ventilated adults. ∆CDPV may be an accurate carotid parameter in certain contexts. Further high-quality studies with more homogenous designs are needed to further validate this technology.

Portal vein pulsatility: An important sonographic tool assessment of systemic congestion for critical ill patients

In this editorial we comment on the article by Kuwahara et al, published in the recent issue of the World Journal of Cardiology. In this interesting paper, the authors showed a correlation between portal vein pulsatility ratio, examined by bedside ultrasonography, and prognosis of hospitalized patients with acute heart failure. Systemic congestion is being notoriously underdetected in the acutely ill population with conventional methods like clinical examination, biomarkers, central venous pressure estimation and X-rays. However, congestion should be a key therapeutic target due to its deleterious effects to end organ function and subsequently patient prognosis. Doppler flow assessment of the abdominal veins is gaining popularity worldwide, as a valuable tool in estimating comprehensively congestion and giving a further insight into hemodynamics and patient management.

Value of carotid corrected flow time or changes value of FTc could be more useful in predicting fluid responsiveness in patients undergoing robot-assisted gynecologic surgery: a prospective observational study

Background

The aim of this study was to evaluate the ability of point-of-care Doppler ultrasound measurements of carotid corrected flow time and its changes induced by volume expansion to predict fluid responsiveness in patients undergoing robot-assisted gynecological surgery.

Methods

In this prospective study, carotid corrected flow time was measured using Doppler images of the common carotid artery before and after volume expansion. The stroke volume index at each time point was recorded using noninvasive cardiac output monitoring with MostCare. Of the 52 patients enrolled, 26 responded.

Results

The areas under the receiver operating characteristic curves of the carotid corrected flow time and changes in carotid corrected flow time induced by volume expansion were 0.82 and 0.67, respectively. Their optimal cut-off values were 357 and 19.5 ms, respectively.

Conclusion

Carotid corrected flow time was superior to changes in carotid corrected flow time induced by volume expansion for predicting fluid responsiveness in this population.

Dynamic monitoring tools for patients admitted to the emergency department with circulatory failure: narrative review with panel-based recommendations

Intravenous fluid therapy is commonly administered in the emergency department (ED). Despite the deleterious potential of over- and under-resuscitation, professional society guidelines continue to recommend administering a fixed volume of fluid in initial resuscitation. Predicting whether a specific patient will respond to fluid therapy remains one of the most important, but challenging questions that ED clinicians face in clinical practice. Surrogate parameters (i.e. blood pressure and heart rate), are widely used in usual care to estimate changes in stroke volume (SV). Due to their inadequacy in estimating SV, noninvasive techniques (e.g. bioreactance, echocardiography, noninvasive finger cuff technology), have been proposed as a more accurate and readily deployable method for assessing flow and preload responsiveness. Dynamic monitoring systems based on cardiac preload challenge and assessment of SV, by using noninvasive and continuous methods, provide more accurate, feasible, efficient, and reasonably accurate strategy for prediction of fluid responsiveness than static measurements. In this article, we aimed to analyze the different methods currently available for dynamic monitoring of preload responsiveness.

The effect of goal-directed fluid therapy on delayed graft function in kidney transplant recipients: A systematic review and meta-analysis

Delayed graft function (DGF) is a common post-operative complication with potential long-term sequelae for many kidney transplant recipients, and hemodynamic factors and fluid status play a role. Fixed perioperative fluid infusions are the standard of care, but more recent evidence in the non-transplant population has suggested benefit with goal-directed fluid strategies based on hemodynamic targets. We searched MEDLINE, EMBASE, Cochrane Controlled Trials Registry and Google Scholar through December 2022 for randomized controlled trials comparing risk of DGF between goal-directed and conventional fluid therapy in adults receiving a living or deceased donor kidney transplant. Effect estimates were reported with odds ratios (OR) and pooled using random effects meta-analysis. We identified 4 studies (205 participants) that met the inclusion criteria. The use of goal-directed fluid therapy had no significant effect on DGF (OR 1.37 95% CI, 0.34-5.6; p = 0.52; I2 = 0.11). Subgroup analysis examining effects among deceased and living kidney donation did not reveal significant differences in the effects of fluid strategy on DGF between subgroups. Overall, the strength of the evidence for goal-directed versus conventional fluid therapy to reduce DGF was of low certainty. Our findings highlight the need for larger trials to determine the effect of goal-directed fluid therapy on this patient-centered outcome.

Feasibility of Fluid Responsiveness Assessment in Patients at Risk for Increased Intracranial Pressure

Background: Effective fluid management is important for patients at risk of increased intracranial pressure (ICP). Maintaining constant cerebral perfusion represents a challenge, as both hypovolemia and fluid overload can severely impact patient outcomes. Fluid responsiveness tests, commonly used in critical care settings, are often deemed potentially hazardous for these patients due to the risk of disrupting cerebral perfusion. Methods: This single-center, prospective, clinical observational study enrolled 40 patients at risk for increased ICP, including those with acute brain injury. Informed consent was obtained from each participant or their legal guardians before inclusion. The study focused on the dynamics of ICP and cerebral perfusion pressure (CPP) changes during the Passive Leg Raise Test (PLRT) and the End-Expiratory Occlusion Test (EEOT). Results: The results demonstrated that PLRT and EEOT caused minor and transient increases in ICP, while consistently maintaining stable CPP. EEOT induced significantly lower ICP elevations, making it particularly suitable for use in high-risk situations. Conclusions: PLRT and EEOT can be considered feasible and safe for assessing fluid responsiveness in patients at risk for increased ICP. Notably, EEOT stands out as a preferred method for high-risk patients, offering a dependable strategy for fluid management without compromising cerebral hemodynamics.

Comparative evaluation of stroke volume variation measured by pulse wave transit time and arterial pressure wave

BACKGROUND

Several monitors have been developed that measure stroke volume (SV) in a beat-to-beat manner. Accordingly, Stroke volume variation (SVV) induced by positive pressure ventilation is widely used to predict fluid responsiveness.

OBJECTIVE

The purpose of this study was to compare the ability of two different methods to predict fluid responsiveness using SVV, stroke volume variation by esCCO (esSVV) and stroke volume variation by FloTrac/VigileoTM (flSVV).

METHODS

esSVV, flSVV, and stroke volume index (SVI) by both monitoring devices of 37 adult patients who underwent laparotomy surgery, were measured. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

The area under the ROC curve (AUC) of esSVV was significantly higher than that of flSVV (p= 0.030). esSVV and flSVV showed cutoff values of 6.1% and 10% respectively, to predict an increase of more than 10% in SVI after fluid challenge. The Youden index for esSVV was higher than flSVV, even with a cutoff value between 6% and 8%.

CONCLUSION

Since esSVV and flSVV showed significant differences in AUC and cutoff values, the two systems were not comparable in predicting fluid responsiveness. Furthermore, it seems that SVV needs to be personalized to accurately predict fluid responsiveness for each patient.

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.

A systematic review and meta-analysis on the effect of goal-directed fluid therapy on postoperative outcomes in renal transplantation surgeries

Introduction

This systematic review and meta-analysis investigated the impact of intraoperative goal-directed therapy (GDT) compared with conventional fluid therapy on postoperative outcomes in renal transplantation recipients, addressing this gap in current literature.

Method

A systematic search of patients aged ≥18 years who have undergone single-organ primary renal transplantations up to June 2022 in PubMed, Embase, Scopus and CINAHL Plus was performed. Primary outcome examined was postoperative renal function. Secondary outcomes assessed were mean arterial pressure at graft reperfusion, intraoperative fluid volume and other postoperative complications. Heterogeneity was tested using I² test. The study protocol was registered on PROSPERO.

Results

A total of 2459 studies were identified. Seven eligible studies on 607 patients were included. Subgroup assessments revealed potential renal protective benefits of GDT, with patients receiving cadaveric grafts showing lower serum creatinine on postoperative days 1 and 3, and patients monitored with arterial waveform analysis devices experiencing lower incidences of postoperative haemodialysis. Overall analysis found GDT resulted in lower incidence of tissue oedema (risk ratio [RR] 0.34, 95% CI 0.15-0.78, P=0.01) and respiratory complications (RR 0.39, 95% CI 0.17-0.90, P=0.03). However, quality of data was deemed low given inclusion of non-randomised studies, presence of heterogeneities and inconsistencies in defining outcomes measures.

Conclusion

While no definitive conclusions can be ascertained given current limitations, this review highlights potential benefits of using GDT in renal transplantation recipients. It prompts the need for further standardised studies to address limitations discussed in this review.

Fluid management in renal transplantation: Is it time to move towards goal-directed directed therapy?

Achieving optimal fluid balance for a patient undergoing major surgery, especially transplant surgery, has always been the lofty goal of peri-operative care,1 which often proves to be an elusive target. While keeping the patient well hydrated improves organ perfusion, being too generous with fluids can result in morbidity, such as venous congestion and tissue oedema. On the flip side, keeping the patient less than well hydrated may potentially reduce blood loss, but water deprivation exposes organs to the risk of injury. The complex process of achieving optimal fluid management is further amplified in renal transplantation, where the interplay of different factors such as tissue oedema leading to vascular anastomotic failure against acute tubular necrosis from intraoperative hypotension and dehydration, creates a convoluted puzzle waiting to unfold. One can no longer rely on the traditional goal of achieving an adequate urine output but rather, depend on other markers to gauge the patient's fluid status.

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.

Internal jugular vein collapsibility does not predict fluid responsiveness in spontaneously breathing patients after cardiac surgery

PURPOSE

The objective of our study was to evaluate the diagnostic accuracy of internal jugular vein (IJV) collapsibility as a predictor of fluid responsiveness in spontaneously breathing patients after cardiac surgery.

METHODS

In this prospective observational study, spontaneously breathing patients were enrolled on the first postoperative day after coronary artery bypass grafting. Hemodynamic data coupled with simultaneous ultrasound assessment of the IJV were collected at baseline and after passive leg raising test (PLR). Continuous cardiac index (CI), stroke volume (SV), and stroke volume variation (SVV) were assessed with FloTracTM/EV1000™. Fluid responsiveness was defined as an increase in CI ≥ 10% after PLR. We compared the differences in measured variables between fluid responders and non-responders and tested the ability of ultrasonographic IJV indices to predict fluid responsiveness.

RESULTS

Fifty-four patients were included in the study. Seventeen (31.5%) were fluid responders. The responders demonstrated significantly lower inspiratory and expiratory diameters of the IJV at baseline, but IJV collapsibility was comparable (P = 0.7). Using the cut-off point of 20%, IJV collapsibility predicted fluid responsiveness with a sensitivity of 76.5% and specificity of 38.9%, ROC AUC 0.55.

CONCLUSION

In spontaneously breathing patients after surgical coronary revascularisation, collapsibility of the internal jugular vein did not predict fluid responsiveness.

Early persistent exposure to high CVP is associated with increased mortality and AKI in septic shock: A retrospective study

PURPOSE

This study's objective was to investigate the association between exposure to different intensities of central venous pressure (CVP) over time in patients with septic shock with 28-day mortality and acute kidney injury (AKI).

MATERIALS AND METHODS

We obtained data from the AmsterdamUMCdb, which includes data on patients ≥18 years old with septic shock undergoing CVP monitoring. The primary outcome was mortality by day 28. Piecewise exponential additive mixed models were used to estimate the strength of the association over time.

RESULTS

9668 patients were included in the study. They exhibited 8.2% overall mortality at 28 days and 41.1% AKI incidence. Daily time-weighted average CVP was strongly associated with increased mortality at 28 days, primarily within 24 h of ICU admission. The mortality rate of patients was lowest when the CVP was 6-12 cmH2O. When the time of high CVP (TWA-CVP >12 cmH2O) exposure within the first 24 h was >5 h, the risk of death increased by 2.69-fold. Additionally, patients exposed to high CVP had a significantly increased risk of developing AKI.

CONCLUSIONS

The optimal CVP range for patients with septic shock within 24 h of ICU admission is 6-12 cmH2O. Mortality increased when patients were exposed to high CVP for >5 h.

Utility of Inferior Vena Cava Distensibility and Respiratory Variation in Peak Aortic Blood Flow Velocity to Predict Fluid Responsiveness in Children with Shock

OBJECTIVES

To evaluate the sensitivity and specificity of inferior vena cava (IVC) distensibility index (∆IVC) and respiratory variation in peak aortic blood flow velocity (∆Vpeak) to predict fluid responsiveness in ventilated children with shock and to find out the best cut-off values for predicting fluid responsiveness.

METHODS

In this prospective observational study, conducted in a pediatric ICU from January 2019 through May 2020, consecutive children aged 2 mo to 17 y with shock requiring fluid bolus were included. ∆IVC and ∆Vpeak were measured before and immediately after 10 ml/kg fluid bolus administration. ∆IVC and ∆Vpeak were compared between responders and non-responders, defined by a change in stroke volume index (SVI) of ≥10%.

RESULTS

Thirty-seven ventilated children [26 (70.4%) boys] with median age of 60 (36, 108) mo were included. The median (IQR) ∆IVC was 21.7% (14.3, 30.9) and the median (IQR) ΔVpeak was 11.3% (7.2, 15.2). Twenty-three (62%) children were fluid responsive. The median (IQR) ∆IVC was higher in responders compared to non-responders [26% (16.9, 36.5) vs. 17.2% (8.4, 21.9); p = 0.018] and mean (SD) ΔVpeak was higher in responders [13.9% (6.1) vs. 8.4% (3.9), p = 0.004]. The prediction of fluid responsiveness with ΔIVC [ROC curve area 0.73 (0.56-0.9), p = 0.01] and ΔVpeak [ROC curve area 0.78 (0.63-0.94), p = 0.002] was similar. The best cut-off of ∆IVC to predict fluid responsiveness was 23% (sensitivity, 60.8%; specificity, 85.7%) and ΔVpeak was 11.3% (sensitivity, 74%; specificity, 86%).

CONCLUSIONS

In this study, authors found that ∆IVC and ΔVpeak were good predictors of fluid responsiveness in ventilated children with shock.

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.

A critical review of the perioperative fluid therapy and hemodynamic monitoring recommendations of the Enhanced Recovery of the Adult Pathway (RICA): A position statement of the fluid therapy and hemodynamic monitoring Subcommittee of the Hemostasis, Transfusion Medicine and Fluid Therapy Section (SHTF) of the Spanish Society of Anesthesiology and Critical Care (SEDAR)

In an effort to standardize perioperative management and improve postoperative outcomes of adult patients undergoing surgery, the Ministry of Health, through the Spanish Multimodal Rehabilitation Group (GERM), and the Aragonese Institute of Health Sciences, in collaboration with multiple Spanish scientific societies and based on the available evidence, published in 2021 the Spanish Intensified Adult Recovery (RICA) guideline. This document includes 12 perioperative measures related to fluid therapy and hemodynamic monitoring. Fluid administration and hemodynamic monitoring are not straightforward but are directly related to postoperative patient outcomes. The Fluid Therapy and Hemodynamic Monitoring Subcommittee of the Hemostasis, Transfusion Medicine and Fluid Therapy Section (SHTF) of the Spanish Society of Anesthesiology and Critical Care (SEDAR) has reviewed these recommendations and concluded that they should be revised as they do not follow an adequate methodology.

Proceedings of the 2022 UAB CRRT Academy: Non-Invasive Hemodynamic Monitoring to Guide Fluid Removal with CRRT and Proliferation of Extracorporeal Blood Purification Devices

In 2022, we celebrated the 15th anniversary of the University of Alabama at Birmingham (UAB) Continuous Renal Replacement Therapy (CRRT) Academy, a 2-day conference attended yearly by an international audience of over 100 nephrology, critical care, and multidisciplinary trainees and practitioners. This year, we introduce the proceedings of the UAB CRRT Academy, a yearly review of select emerging topics in the field of critical care nephrology that feature prominently in the conference. First, we review the rapidly evolving field of non-invasive hemodynamic monitoring and its potential to guide fluid removal by renal replacement therapy (RRT). We begin by summarizing the accumulating data associating fluid overload with harm in critical illness and the potential for harm from end-organ hypoperfusion caused by excessive fluid removal with RRT, underscoring the importance of accurate, dynamic assessment of volume status. We describe four applications of point-of-care ultrasound used to identify patients in need of urgent fluid removal or likely to tolerate fluid removal: lung ultrasound, inferior vena cava ultrasound, venous excess ultrasonography, and Doppler of the left ventricular outflow track to estimate stroke volume. We briefly introduce other minimally invasive hemodynamic monitoring technologies before concluding that additional prospective data are urgently needed to adapt these technologies to the specific task of fluid removal by RRT and to learn how best to integrate them into practical fluid-management strategies. Second, we focus on the growth of novel extracorporeal blood purification devices, starting with brief reviews of the inflammatory underpinnings of multiorgan dysfunction and the specific applications of pathogen, endotoxin, and/or cytokine removal and immunomodulation. Finally, we review a series of specific adsorptive technologies, several of which have seen substantial clinical use during the COVID-19 pandemic, describing their mechanisms of target removal, the limited existing data supporting their efficacy, ongoing and future studies, and the need for additional prospective trials.

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.

The Effects of Restrictive Fluid Resuscitation on the Clinical Outcomes in Patients with Sepsis or Septic Shock: A Meta-Analysis of Randomized-Controlled Trials

This study aims to assess the impact of a restrictive resuscitation strategy on the outcomes of patients with sepsis and septic shock. This meta-analysis was conducted in accordance with the recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P) guidelines. A systematic search was performed in databases, including PubMed, Web of Science, EMBASE, and the Cochrane Library, covering the period from the inception of the database to August 2023, with no limitations on the language of publication. Outcomes assessed in the meta-analysis included mortality, duration of intensive care unit (ICU) stay in days, duration of mechanical ventilation in days, acute kidney injury (AKI) or the need for renal replacement therapy (RRT), and length of hospital stay in days. Overall, 12 studies met the inclusion criteria and were included in the present meta-analysis. The findings of this study indicate that although the risk of mortality was lower in fluid restriction compared to the control group, the difference was statistically insignificant (risk ratio (RR): 0.98; 95% confidence interval (CI): 0.9-1.05; P value: 0.61). Additionally, the duration of mechanical ventilation was significantly shorter in the restrictive fluid group compared to its counterparts (mean difference (MD): -1.02; 95% CI: -1.65 to -0.38; P value: 0.003). There were no significant differences found in relation to the duration of ICU stays, the incidence of AKI, the requirement for RRT, or the length of hospital stays measured in days.

Hemodynamic management of septic shock: beyond the Surviving Sepsis Campaign guidelines

Although the Surviving Sepsis Campaign guidelines provide standardized and generalized guidance, they are less individualized. This review focuses on recent updates in the hemodynamic management of septic shock. Monitoring and intervention for septic shock should be personalized according to the phase of shock. In the salvage phase, fluid resuscitation and vasopressors should be given to provide life-saving tissue perfusion. During the optimization phase, tissue perfusion should be optimized. In the stabilization and de-escalation phases, minimal fluid infusion and safe fluid removal should be performed, respectively, while preserving organ perfusion. There is controversy surrounding the use of restrictive versus liberal fluid strategies after initial resuscitation. Fluid administration after initial resuscitation should depend upon the patient's fluid responsiveness and requires individualized management. A number of dynamic tests have been proposed to monitor fluid responsiveness, which can help clinicians decide whether to give fluid or not. The optimal timing for the initiation of vasopressor agents is unknown. Recent data suggest that early vasopressor initiation should be considered. Inotropes can be considered in patients with decreased cardiac contractility associated with impaired tissue perfusion despite adequate volume status and arterial blood pressure. Venoarterial extracorporeal membrane oxygenation should be considered for refractory septic shock with severe cardiac systolic dysfunction.

Cardiopulmonary interactions-which monitoring tools to use?

Heart-lung interactions occur due to the mechanical influence of intrathoracic pressure and lung volume changes on cardiac and circulatory function. These interactions manifest as respiratory fluctuations in venous, pulmonary, and arterial pressures, potentially affecting stroke volume. In the context of functional hemodynamic monitoring, pulse or stroke volume variation (pulse pressure variation or stroke volume variability) are commonly employed to assess volume or preload responsiveness. However, correct interpretation of these parameters requires a comprehensive understanding of the physiological factors that determine pulse pressure and stroke volume. These factors include pleural pressure, venous return, pulmonary vessel function, lung mechanics, gas exchange, and specific cardiac factors. A comprehensive knowledge of heart-lung physiology is vital to avoid clinical misjudgments, particularly in cases of right ventricular (RV) failure or diastolic dysfunction. Therefore, when selecting monitoring devices or technologies, these factors must be considered. Invasive arterial pressure measurements of variations in breath-to-breath pressure swings are commonly used to monitor heart-lung interactions. Echocardiography or pulmonary artery catheters are valuable tools for differentiating preload responsiveness from right ventricular failure, while changes in diastolic function should be assessed alongside alterations in airway or pleural pressure, which can be approximated by esophageal pressure. In complex clinical scenarios like ARDS, combined forms of shock or right heart failure, additional information on gas exchange and pulmonary mechanics aids in the interpretation of heart-lung interactions. This review aims to describe monitoring techniques that provide clinicians with an integrative understanding of a patient's condition, enabling accurate assessment and patient care.

Diagnostic accuracy of the peripheral venous pressure variation induced by an alveolar recruitment maneuver to predict fluid responsiveness during high-risk abdominal surgery

BACKGROUND

In patients undergoing high-risk surgery, it is recommended to titrate fluid administration using stroke volume or a dynamic variable of fluid responsiveness (FR). However, this strategy usually requires the use of a hemodynamic monitor and/or an arterial catheter. Recently, it has been shown that variations of central venous pressure (ΔCVP) during an alveolar recruitment maneuver (ARM) can predict FR and that there is a correlation between CVP and peripheral venous pressure (PVP). This prospective study tested the hypothesis that variations of PVP (ΔPVP) induced by an ARM could predict FR.

METHODS

We studied 60 consecutive patients scheduled for high-risk abdominal surgery, excluding those with preoperative cardiac arrhythmias or right ventricular dysfunction. All patients had a peripheral venous catheter, a central venous catheter and a radial arterial catheter linked to a pulse contour monitoring device. PVP was always measured via an 18-gauge catheter inserted at the antecubital fossa. Then an ARM consisting of a standardized gas insufflation to reach a plateau of 30 cmH₂O for 30 s was performed before skin incision. Invasive mean arterial pressure (MAP), pulse pressure, heart rate, CVP, PVP, pulse pressure variation (PPV), and stroke volume index (SVI) were recorded before ARM (T1), at the end of ARM (T2), before volume expansion (T3), and one minute after volume expansion (T4). Receiver-operating curves (ROC) analysis with the corresponding grey zone approach were performed to assess the ability of ∆PVP (index test) to predict FR, defined as an ≥ 10% increase in SVI following the administration of a 4 ml/kg balanced crystalloid solution over 5 min.

RESULTS

∆PVP during ARM predicted FR with an area under the ROC curve of 0.76 (95%CI, 0.63 to 0.86). The optimal threshold determined by the Youden Index was a ∆PVP value of 5 mmHg (95%CI, 4 to 6) with a sensitivity of 66% (95%CI, 47 to 81) and a specificity of 82% (95%CI, 63 to 94). The AUC's for predicting FR were not different between ΔPVP, ΔCVP, and PPV.

CONCLUSION

During high-risk abdominal surgery, ∆PVP induced by an ARM can moderately predict FR. Nevertheless, other hemodynamic variables did not perform better.

Mechanical Circulatory Support and Critical Care Management of High-Risk Acute Pulmonary Embolism

Hemodynamically significant pulmonary embolism (PE) remains a widely prevalent, underdiagnosed condition associated with mortality rates as high as 30%. The main driver of poor outcomes is acute right ventricular failure that remains clinically challenging to diagnose and requires critical care management. Treatment of high-risk (or massive) acute PE has traditionally included systemic anticoagulation and thrombolysis. Mechanical circulatory support, including both percutaneous and surgical approaches, are emerging as treatment options for refractory shock due to acute right ventricular failure in the setting of high-risk acute pulmonary embolism.

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.