Review of A Large Clinical Series: Association of Cumulative Fluid Balance on Outcome in Acute Lung Injury: A Retrospective Review of the ARDSnet Tidal Volume Study Cohort

Impact of a Pharmacist-Driven Medication Diluent Volume Optimization Protocol on Fluid Balance and Outcomes in Critically Ill Patients

Background: Volume overload (VO) is common in the intensive care unit (ICU) and associated with negative outcomes. Approaches have been investigated to curtail VO; however, none specifically focused on medication diluent volume optimization. Objective: Investigate the impact of a pharmacist-driven medication diluent volume optimization protocol on fluid balance in critically ill patients. Methods: A prospective, pilot study was conducted in a medical ICU during October 2021 to December 2021 (pre) and February 2022 to April 2022 (post). A pharmacist-driven medication diluent volume optimization protocol focusing on vasopressor and antimicrobial diluent volumes was implemented. Demographics and clinical data were collected during ICU admission up to 7 days. The primary outcome was net fluid balance on day 3. Secondary outcomes were medication volumes administered, net fluid balance, ICU length of stay, and mortality. Results: Supply chain shortages caused the study to stop at the end of February 2022. Overall, 152 patients were included (123 pre group, 29 post group). The most common admission diagnosis was acute respiratory failure (35%). Vasopressors and antimicrobials were utilized in 47% and 66% of patients, respectively. Net fluid balance on day 3 was greater but not significant in the post group (227.1 mL [-1840.3 to 3483.7] vs 2012.3 mL [-2686.0 to 4846.0]; P = .584). Antimicrobial diluent volumes were significantly less in the post group. No differences were seen in other secondary outcomes. Protocol group assignment was not associated with net fluid balance on day 3. Conclusion: Despite decreasing antimicrobial volume contributions, optimizing diluent volumes alone did not significantly impact overall volume status. Future studies should focus on comprehensive approaches to medication diluent optimization and fluid stewardship.

Identifying novel clinical phenotypes of acute respiratory distress syndrome using trajectories of daily fluid balance: a secondary analysis of randomized controlled trials

BACKGROUND

Previously identified phenotypes of acute respiratory distress syndrome (ARDS) could not reveal the dynamic change of phenotypes over time. We aimed to identify novel clinical phenotypes in ARDS using trajectories of fluid balance, to test whether phenotypes respond differently to different treatment, and to develop a simplified model for phenotype identification.

METHODS

FACTT (conservative vs liberal fluid management) trial was classified as a development cohort, joint latent class mixed models (JLCMMs) were employed to identify trajectories of fluid balance. Heterogeneity of treatment effect (HTE) for fluid management strategy across phenotypes was investigated. We also constructed a parsimonious probabilistic model using baseline data to predict the fluid trajectories in the development cohort. The trajectory groups and the probabilistic model were externally validated in EDEN (initial trophic vs full enteral feeding) trial.

RESULTS

Using JLCMM, we identified two trajectory groups in the development cohort: Class 1 (n = 758, 76.4% of the cohort) had an early positive fluid balance, but achieved negative fluid balance rapidly, and Class 2 (n = 234, 24.6% of the cohort) was characterized by persistent positive fluid balance. Compared to Class 1 patients, patients in Class 2 had significantly higher 60-day mortality (53.5% vs. 17.8%, p < 0.001), and fewer ventilator-free days (0 vs. 20, p < 0.001). A significant HTE between phenotypes and fluid management strategies was observed in the FACTT. An 8-variables model was derived for phenotype assignment.

CONCLUSIONS

We identified and validated two novel clinical trajectories for ARDS patients, with both prognostic and predictive enrichment. The trajectories of ARDS can be identified with simple classifier models.

Fluid Management in Acute Respiratory Failure

Fluid management in acute respiratory failure is an area of uncertainty requiring a delicate balance of resuscitation and fluid removal to manage hypoperfusion and avoidance of hypoxemia. Overall, a restrictive fluid strategy (minimizing fluid administration) and careful attention to overall fluid balance may be beneficial after initial resuscitation and does not have major side effects. Further studies are needed to improve our understanding of patients who will benefit from a restrictive or liberal fluid management strategy.

Fluid balance control in critically ill patients: results from as-treated analyses of POINCARE-2 randomized trial

BACKGROUND

Intention-to-treat analyses of POINCARE-2 trial led to inconclusive results regarding the effect of a conservative fluid balance strategy on mortality in critically ill patients. The present as-treated analysis aimed to assess the effectiveness of actual exposure to POINCARE-2 strategy on 60-day mortality in critically ill patients.

METHODS

POINCARE‑2 was a stepped wedge randomized controlled trial. Eligible patients were ≥ 18 years old, under mechanical ventilation and had an expected length of stay in ICU > 24 h. POINCARE-2 strategy consisted of daily weighing over 14 days, and subsequent restriction of fluid intake, administration of diuretics, and/or ultrafiltration. We computed a score of exposure to the strategy based on deviations from the strategy algorithm. We considered patients with a score ≥ 75 as exposed to the strategy. We used logistic regression adjusted for confounders (ALR) or for an instrumental variable (IVLR). We handled missing data using multiple imputations.

RESULTS

A total of 1361 patients were included. Overall, 24.8% of patients in the control group and 69.4% of patients in the strategy group had a score of exposure ≥ 75. Exposure to the POINCARE-2 strategy was not associated with 60-day all-cause mortality (ALR: OR 1.2, 95% CI 0.85-1.55; IVLR: OR 1.0, 95% CI 0.76-1.33).

CONCLUSION

Actual exposure to POINCARE-2 conservative strategy was not associated with reduced mortality in critically ill patients. Trial registration POINCARE-2 trial is registered at ClinicalTrials.gov (NCT02765009). Registered 29 April 2016.

Early transthoracic echocardiography and long-term mortality in moderate- to-severe acute respiratory distress syndrome: An analysis of the Medical Information Mart for Intensive Care database

BACKGROUND

The clinical use of transthoracic echocardiography (TTE) in patients with acute respiratory distress syndrome (ARDS) in the intensive care unit (ICU) has dramatically increased, its impact on long-term prognosis in these patients has not been studied. This study aimed to explore the effect of early-TTE on long-term mortality in patients with moderate-to-severe ARDS in ICU.

METHODS

A total of 2833 patients with moderate-to-severe ARDS who had or had not received early-TTE were obtained from the Medical Information Mart for Intensive Care (MIMIC-III) database after imputing missing values by a random forest model, patients were divided into early-TTE group and non-early-TTE group according to whether they received TTE examination in ICU. A variety of statistical methods were used to balance 41 covariates and increase the reliability of this study, including propensity score matching, inverse probability of treatment weight, covariate balancing propensity score, multivariable regression, and doubly robust estimation. Chi-Square test and t-tests were used to examine the differences between groups for categorical and continuous data, respectively.

RESULTS

There was a significant improvement in 90-day mortality in the early-TTE group compared to non-early-TTE group (odds ratio  =  0.79, 95% CI: 0.64-0.98, p-value  =  0.036), revealing a beneficial effect of early-TTE. Net-input was significantly decreased in the early-TTE group on the third day of ICU admission and throughout the ICU stay, compared with non-early-TTE group (838.57 vs. 1181.89 mL, p-value  =  0.014; 4542.54 vs. 8025.25 mL, p-value  =  0.05). There was a significant difference in the reduction of serum lactate between the two groups, revealing the beneficial effect of early-TTE (0.59 vs. 0.83, p-value  =  0.009). Furthermore, the reduction in the proportion of acute kidney injury demonstrated a correlation between early-TTE and kidney protection (33% vs. 40%, p-value < 0.001).

CONCLUSIONS

Early application of TTE is beneficial to improve the long-term mortality of patients with moderate-to-severe ARDS.

The numerical value of fluid balance to predict survival in neonates requiring extracorporeal membrane oxygenation

BACKGROUND

The aim of this study was to understand numerical variation of fluid balance in neonates requiring extracorporeal membrane oxygenation (ECMO) and to assess the relationship between hourly fluid balance and mortality.

METHODS

This is a prospective cohort study. All neonates supported by ECMO were enrolled from October 2011 to September 2017. All of the enrolled neonates were divided into survival group and non- survival group. The numerical value of fluid balance of the enrolled neonates were recorded at 6 hours, 12 hours, 24 hours, 36 hours and 48 hours after initiation of ECMO respectively. The differences between the two groups were compared. The numerical value of fluid balance predict survival by the receiver operating characteristic (ROC) curve.

RESULTS

Forty-eight neonates were enrolled, in which 35 cases were survival and the survival rate was 72.9%. The numerical value of fluid balance in the survival group were lower than that in the non-survival group at 6 hours, 12 hours, 24 hours, 36 hours and 48 hours after ECMO(all P<0.05). The area under ROC curve at 6h, 12h, 24h, 36h and 48h after initiation of ECMO was 0.835, 0.900, 0.839, 0.909 and 0.974 respectively. There were statistically significant in the numerical value of fluid balance predicting survival (all P<0.05) and a high sensitivity, specificity and positive predictive value at the each time point.

CONCLUSIONS

The negative hourly fluid balance were associated with decreased mortality, and the lower the numerical value of fluid balance in neonates requiring ECMO, the higher the survival rate.

End-expiratory Occlusion Test and Mini-fluid Challenge Test for Predicting Fluid Responsiveness in Acute Circulatory Failure

Introduction

Predicting which patients with acute circulatory failure will respond to the fluid by an increase in cardiac output is a daily challenge. End-expiratory occlusion test (EEOT) and mini-fluid challenge (MFC) can be used for assessing fluid responsiveness in patients with spontaneous breathing activity, cardiac arrhythmias, low-tidal volume and/or low lung compliance.

Methods

The objective of the study is to evaluate the value of EEOT and MFC-induced rise in left ventricular outflow tract (LVOT) velocity time integral (VTI) in predicting fluid responsiveness in acute circulatory failure in comparison to the passive leg-raising (PLR) test. Hundred critically ill ventilated and sedated patients with acute circulatory failure were studied. LVOT VTI was measured by transthoracic echocardiography before and after EEOT (interrupting the ventilator at end-expiration over 15 s), and before and after MFC (100 ml of Ringer lactate was infused over 1 min). The variation of LVOT VTI after EEOT and the MFC was calculated from the baseline. Sensitivity, specificity, and area under the receiver-operating characteristic (AUROC) curve of LVOT VTI after EEOT and MFC to predict fluid responsiveness were determined.

Results

After PLR, stroke volume (SV) increased by ≥12% in 49 patients, who were defined as responders and 34 patients in whom the increase in SV <12% were defined as nonresponders. A cutoff of 9.1% Change in VTI after MFC (ΔVTIMFC) predicted fluid responsiveness with an AUROC of 0.96 (P < 0.001) with sensitivity and specificity of 91.5% and 88.9%, respectively. Change in VTI after EEOT (ΔVTIEEOT) >4.3% predicted fluid responsiveness with sensitivity and specificity 89.4% and 88.9%, respectively, with an AUROC of 0.97 (P < 0.001), but in 17 patients, EEOT was not possible because triggering of the ventilator by the patient's inspiratory effort.

Conclusion

In conclusion, in mechanically ventilated patients with acute circulatory failure Δ VTIMFC and Δ VTI EEOT accurately predicts fluid responsiveness.

Integrated ultrasonographic approach to evaluate fluid responsiveness in critically ill patients

In patients with acute circulatory failure, we tested the feasibility of the evaluation of the fluid-responsiveness (FR) by a combined approach with echocardiography and lung ultrasound. We enrolled 113 consecutive patients admitted to the Emergency Department High-Dependency Unit of Careggi University-Hospital from January 2015 to June 2020. We assessed: (1) inferior vena cava collapsibility index (IVCCI); (2) the variation of aortic flow (VTIAo) during the passive leg raising test (PLR); (3) the presence of interstitial syndrome by lung ultrasound. FR was defined as an increase in the VTIAo > 10% during PLR or IVCCI ≥ 40%. FR patients were treated with fluid and those non-FR with diuretics or vasopressors. The therapeutic strategy was reassessed after 12 h. The goal was to maintain the initial strategy. Among 56 FR patients, at lung ultrasound, 15 patients showed basal interstitial syndrome and 4 all-lung involvement. One fluid bolus was given to 51 patients. Among 57 non-FR patients, 26 patients showed interstitial syndrome at lung ultrasound (basal fields in 14, all lungs in 12). We administered diuretics to 21 patients and vasopressors to 4 subjects. We had to change the initial treatment plan in 9% non-FR patients and in 12% FR patients (p = NS). In the first 12 h after the evaluation, non-FR patients received significantly less fluids compared to those FR (1119 ± 410 vs 2010 ± 1254 ml, p < 0.001). The evaluation of the FR based on echocardiography and lung ultrasound was associated with the reduction in fluid administration for non-FR patients compared with those FR.

Optimizing Fluid Management Guided by Volumetric Parameters in Patients with Sepsis and ARDS

We compared two de-escalation strategies guided by either extravascular lung water or global end-diastolic volume-oriented algorithms in patients with sepsis and ARDS. Sixty patients with sepsis and ARDS were randomized to receive de-escalation fluid therapy, guided either by the extravascular lung water index (EVLWI, n = 30) or the global end-diastolic volume index (GEDVI, n = 30). In cases of GEDVI > 650 mL/m² or EVLWI > 10 mL/kg, diuretics and/or controlled ultrafiltration were administered to achieve the cumulative 48-h fluid balance in the range of 0 to -3000 mL. During 48 h of goal-directed de-escalation therapy, we observed a decrease in the SOFA score (p < 0.05). Extravascular lung water decreased only in the EVLWI-oriented group (p < 0.001). In parallel, PaO₂/FiO₂ increased by 30% in the EVLWI group and by 15% in the GEDVI group (p < 0.05). The patients with direct ARDS demonstrated better responses to dehydration therapy concerning arterial oxygenation and lung fluid balance. In sepsis-induced ARDS, both fluid management strategies, based either on GEDVI or EVLWI, improved arterial oxygenation and attenuated organ dysfunction. The de-escalation therapy was more efficient for direct ARDS.

Early Restrictive or Liberal Fluid Management for Sepsis-Induced Hypotension

BACKGROUND

Intravenous fluids and vasopressor agents are commonly used in early resuscitation of patients with sepsis, but comparative data for prioritizing their delivery are limited.

METHODS

In an unblinded superiority trial conducted at 60 U.S. centers, we randomly assigned patients to either a restrictive fluid strategy (prioritizing vasopressors and lower intravenous fluid volumes) or a liberal fluid strategy (prioritizing higher volumes of intravenous fluids before vasopressor use) for a 24-hour period. Randomization occurred within 4 hours after a patient met the criteria for sepsis-induced hypotension refractory to initial treatment with 1 to 3 liters of intravenous fluid. We hypothesized that all-cause mortality before discharge home by day 90 (primary outcome) would be lower with a restrictive fluid strategy than with a liberal fluid strategy. Safety was also assessed.

RESULTS

A total of 1563 patients were enrolled, with 782 assigned to the restrictive fluid group and 781 to the liberal fluid group. Resuscitation therapies that were administered during the 24-hour protocol period differed between the two groups; less intravenous fluid was administered in the restrictive fluid group than in the liberal fluid group (difference of medians, -2134 ml; 95% confidence interval [CI], -2318 to -1949), whereas the restrictive fluid group had earlier, more prevalent, and longer duration of vasopressor use. Death from any cause before discharge home by day 90 occurred in 109 patients (14.0%) in the restrictive fluid group and in 116 patients (14.9%) in the liberal fluid group (estimated difference, -0.9 percentage points; 95% CI, -4.4 to 2.6; P = 0.61); 5 patients in the restrictive fluid group and 4 patients in the liberal fluid group had their data censored (lost to follow-up). The number of reported serious adverse events was similar in the two groups.

CONCLUSIONS

Among patients with sepsis-induced hypotension, the restrictive fluid strategy that was used in this trial did not result in significantly lower (or higher) mortality before discharge home by day 90 than the liberal fluid strategy. (Funded by the National Heart, Lung, and Blood Institute; CLOVERS ClinicalTrials.gov number, NCT03434028.).

A Study to Compare Ultrasound-guided and Clinically Guided Fluid Management in Children with Septic Shock

Background

To evaluate the role of ultrasound during initial fluid resuscitation along with clinical guidance in reducing the incidence of fluid overload on day 3 in children with septic shock.

Materials and methods

It was a prospective, parallel limb open-labeled randomized controlled superiority trial done in the PICU of a government-aided tertiary care hospital in Eastern India. Patient enrolment took place between June 2021 and March 2022. Fifty-six children aged between 1 month and 12 years, with proven or suspected septic shock, were randomized to receive either ultrasound-guided or clinically guided fluid boluses (1:1 ratio) and subsequently followed up for various outcomes. The primary outcome was frequency of fluid overload on day 3 of admission. The treatment group received ultrasound-guided fluid boluses along with the clinical guidance and the control group received the same but without ultrasound guidance upto 60 mL/kg of fluid boluses.

Results

The frequency of fluid overload on day 3 of admission was significantly lower in the ultrasound group (25% vs 62%, p = 0.012) as was the median (IQR) cumulative fluid balance percentage on day 3 [6.5 (3.3-10.3) vs 11.3 (5.4-17.5), p = 0.02]. The amount of fluid bolus administered was also significantly lower by ultrasound [median 40 (30-50) vs 50 (40-80) mL/kg, p = 0.003]. Resuscitation time was shorter in the ultrasound group (13.4 ± 5.6 vs 20.5 ± 8 h, p = 0.002).

Conclusion

Ultrasound-guided fluid boluses were found to be significantly better than clinically guided therapy, in preventing fluid overload and its associated complications in children with septic shock. These factors make ultrasound a potentially useful tool for resuscitation of children with septic shock in the PICU.

How to cite this article

Kaiser RS, Sarkar M, Raut SK, Mahapatra MK, Uz Zaman MA, Roy O, et al. A Study to Compare Ultrasound-guided and Clinically Guided Fluid Management in Children with Septic Shock. Indian J Crit Care Med 2023;27(2):139-146.

Cirrhosis Management in the Intensive Care Unit

Patients with cirrhosis frequently require admission to the intensive care unit as complications arise in the course of their disease. These admissions are associated with high short- and long-term morbidity and mortality. Thus, understanding and characterizing complications and unique needs of patients with cirrhosis and acute-on-chronic liver failure helps providers identify appropriate level of care and evidence-based treatments. While there is no widely accepted critical care admission criteria for patients with cirrhosis, the presence of organ failure and primary or nosocomial infections are associated with particularly high in-hospital mortality. Optimal management of patients with cirrhosis in the critical care setting requires a system-based approach that acknowledges deviations from canonical pathophysiology. In this review, we discuss appropriate considerations and evidence-based practices for the general care of patients with cirrhosis and critical illness.

POCUS and Fluid Responsiveness on Venoarterial ECMO

VA ECMO allows organ perfusion and oxygenation while awaiting myocardial recovery, cardiac transplantation, or long-term mechanical circulatory support. Diagnosis of hospital-acquired pneumonia (HAP) is a daily challenge for the clinician managing patients on venoarterial ECMO. Lung ultrasound (US) can be a valuable tool as the initial imaging modality for the diagnosis of pneumonia. Point-of-care US (POCUS) is broadly used in patients with ARDS. POCUS is recommended to be performed regularly in COVID-19 patients for respiratory failure management. In this review, we summarized the US characteristics of COVID-19 patients, mainly focusing on lung US and echocardiography. Point-of-care lung US (LUS) was demonstrated to be an effective tool in case of acute respiratory failure for ICU patients, community-acquired pneumonia, and ventilator-associated pneumonia. This review describes the usefulness of LUS in the early detection of HAP in cardiac critically ill patients under VA ECMO as well as assess its sonographic features.

The volume of infusion fluids correlates with treatment outcomes in critically ill trauma patients

Background

Appropriate fluid management is essential in the treatment of critically ill trauma patients. Both insufficient and excessive fluid volume can be associated with worse outcomes. Intensive fluid resuscitation is a crucial element of early resuscitation in trauma; however, excessive fluid infusion may lead to fluid accumulation and consequent complications such as pulmonary edema, cardiac failure, impaired bowel function, and delayed wound healing. The aim of this study was to examine the volumes of fluids infused in critically ill trauma patients during the first hours and days of treatment and their relationship to survival and outcomes.

Methods

We retrospectively screened records of all consecutive patients admitted to the intensive care unit (ICU) from the beginning of 2019 to the end of 2020. All adults who were admitted to ICU after trauma and were hospitalized for a minimum of 2 days were included in the study. We used multivariate regression analysis models to assess a relationship between volume of infused fluid or fluid balance, age, ISS or APACHE II score, and mortality. We also compared volumes of fluids in survivors and non-survivors including additional analyses in subgroups depending on disease severity (ISS score, APACHE II score), blood loss, and age.

Results

A total of 52 patients met the inclusion criteria for the study. The volume of infused fluids and fluid balance were positively correlated with mortality, complication rate, time on mechanical ventilation, length of stay in the ICU, INR, and APTT. Fluid volumes were significantly higher in non-survivors than in survivors at the end of the second day of ICU stay (2.77 vs. 2.14 ml/kg/h) and non-survivors had a highly positive fluid balance (6.21 compared with 2.48 L in survivors).

Conclusion

In critically ill trauma patients, worse outcomes were associated with higher volumes of infusion fluids and a more positive fluid balance. Although fluid resuscitation is lifesaving, especially in the first hours after trauma, fluid infusion should be limited to a necessary minimum to avoid fluid overload and its negative consequences.

Echocardiographic indicators of fluid responsiveness in hospitalized dogs with compromised hemodynamics and tissue hypoperfusion

OBJECTIVE

To evaluate the accuracy of selected echocardiographic variables used to predict fluid responsiveness in hospitalized dogs with compromised hemodynamics and tissue hypoperfusion.

DESIGN

Diagnostic test study in a prospective cohort of hospitalized dogs.

SETTING

Veterinary referral clinics.

ANIMALS

Forty-four hospitalized dogs with compromised hemodynamics and tissue hypoperfusion were utilized in this study.

INTERVENTIONS

Echocardiographic examination before and after fluid replacement with 30 ml/kg of lactated Ringer's solution.

MEASUREMENTS AND MAIN RESULTS

Pre-fluid replacement measurements of velocity of transmitral E wave (E-peak), the left ventricular end-diastolic internal diameter normalized to body weight (LVIDdN), and the left ventricular end-systolic internal diameter normalized to body weight (LVIDsN) were significantly lower in fluid-responsive patients compared with nonresponders (P < 0.001). The area under the receiver operating characteristic curve (AUROC) with its 95% confidence interval (CI) for each significant predictor was as follows: E-peak 0.907 (0.776-1.000, P < 0.001) and LVIDdN 0.919 (0.801-1.000, P < 0.001). The predictive capacity of LVIDsN was not significantly better than chance (AUROC, 0.753; 95% CI, 0.472-1.000, P = 0.078). A significant negative linear correlation was observed between the percentage of increase in velocity-time integral after expansion and the echocardiographic variables LVIDdN (r_s  = -0.452, P = 0.023) and E-peak (r_s  = -0.396, P = 0.008) pre-fluid replacement. The intraobserver and interobserver variability was very low (<5 %) for all measurements.

CONCLUSIONS

In this study using critically ill dogs with compromised hemodynamics and tissue hypoperfusion, pre-fluid replacement measurements of LVIDdN and E-peak adequately predict fluid responsiveness. Because a small number of fluid nonresponders were involved in the present study (11.4%), further studies that include larger numbers of fluid-nonresponsive animals are required.

A system theory based digital model for predicting the cumulative fluid balance course in intensive care patients

Background: Surgical interventions can cause severe fluid imbalances in patients undergoing cardiac surgery, affecting length of hospital stay and survival. Therefore, appropriate management of daily fluid goals is a key element of postoperative intensive care in these patients. Because fluid balance is influenced by a complex interplay of patient-, surgery- and intensive care unit (ICU)-specific factors, fluid prediction is difficult and often inaccurate. Methods: A novel system theory based digital model for cumulative fluid balance (CFB) prediction is presented using recorded patient fluid data as the sole parameter source by applying the concept of a transfer function. Using a retrospective dataset of n = 618 cardiac intensive care patients, patient-individual models were created and evaluated. RMSE analyses and error calculations were performed for reasonable combinations of model estimation periods and clinically relevant prediction horizons for CFB. Results: Our models have shown that a clinically relevant time horizon for CFB prediction with the combination of 48 h estimation time and 8-16 h prediction time achieves high accuracy. With an 8-h prediction time, nearly 50% of CFB predictions are within ±0.5 L, and 77% are still within the clinically acceptable range of ±1.0 L. Conclusion: Our study has provided a promising proof of principle and may form the basis for further efforts in the development of computational models for fluid prediction that do not require large datasets for training and validation, as is the case with machine learning or AI-based models. The adaptive transfer function approach allows estimation of CFB course on a dynamically changing patient fluid balance system by simulating the response to the current fluid management regime, providing a useful digital tool for clinicians in daily intensive care.

Perfusion-based deresuscitation during continuous renal replacement therapy: A before-after pilot study (The early dry Cohort)

BACKGROUND

Active fluid removal has been suggested to improve prognosis following the resolution of acute circulatory failure. We have implemented a routine care protocol to guide fluid removal during continuous renal replacement therapy (CRRT). We designed a before-after pilot study to evaluate the impact of this deresuscitation strategy on the fluid balance.

METHODS

Consecutive ICU patients suffering from fluid overload and undergoing CRRT for acute kidney injury underwent a perfusion-based deresuscitation protocol combining a restrictive intake, net ultrafiltration (UFnet) of 2 mL/kg/h, and monitoring of perfusion (early dry group, N = 42) and were compared to a historical group managed according to usual practices (control group, N = 45). The primary outcome was the cumulative fluid balance at day 5 or at discharge.

RESULTS

Adjusted cumulative fluid balance was significantly lower in the early dry group (median [IQR]: -7784 [-11,833 to -2933] mL) compared to the control group (-3492 [-9935 to -1736] mL; p = 0.04). The difference was mainly driven by a greater daily UFnet (31 [22-46] mL/kg/day vs. 24 [15-32] mL/kg/day; p = 0.01). There was no significant difference between both groups regarding hemodynamic tolerance.

CONCLUSION

Our perfusion-based deresuscitation protocol achieved a greater negative cumulative fluid balance compared to standard practices and was hemodynamically well tolerated.

Overview of the Medical Management of the Critically Ill Patient

The medical management of the critically ill patient focuses predominantly on treatment of the underlying condition (e g, sepsis or respiratory failure). However, in the past decade, the importance of initiating early prophylactic treatment for complications arising from care in the intensive care unit setting has become increasingly apparent. As survival from critical illness has improved, there is an increased prevalence of postintensive care syndrome-defined as a decline in physical, cognitive, or psychologic function among survivors of critical illness. The Intensive Care Unit Liberation Bundle, a major initiative of the Society of Critical Care Medicine, is centered on facilitating the return to normal function as early as possible, with the intent of minimizing iatrogenic harm during necessary critical care. These concepts are universally applicable to patients seen by nephrologists in the intensive care unit and may have particular relevance for patients with kidney failure either on dialysis or after kidney transplant. In this article, we will briefly summarize some known organ-based consequences associated with critical illness, review the components of the ABCDEF bundle (the conceptual framework for Intensive Care Unit Liberation), highlight the role nephrologists can play in implementing and complying with the ABCDEF bundle, and briefly discuss areas for additional research.

Association between early cumulative fluid balance and successful liberation from invasive ventilation in COVID-19 ARDS patients — insights from the PRoVENT-COVID study: a national, multicenter, observational cohort analysis

Background

Increasing evidence indicates the potential benefits of restricted fluid management in critically ill patients. Evidence lacks on the optimal fluid management strategy for invasively ventilated COVID-19 patients. We hypothesized that the cumulative fluid balance would affect the successful liberation of invasive ventilation in COVID-19 patients with acute respiratory distress syndrome (ARDS).

Methods

We analyzed data from the multicenter observational ‘PRactice of VENTilation in COVID-19 patients’ study. Patients with confirmed COVID-19 and ARDS who required invasive ventilation during the first 3 months of the international outbreak (March 1, 2020, to June 2020) across 22 hospitals in the Netherlands were included. The primary outcome was successful liberation of invasive ventilation, modeled as a function of day 3 cumulative fluid balance using Cox proportional hazards models, using the crude and the adjusted association. Sensitivity analyses without missing data and modeling ARDS severity were performed.

Results

Among 650 patients, three groups were identified. Patients in the higher, intermediate, and lower groups had a median cumulative fluid balance of 1.98 L (1.27–7.72 L), 0.78 L (0.26–1.27 L), and − 0.35 L (− 6.52–0.26 L), respectively. Higher day 3 cumulative fluid balance was significantly associated with a lower probability of successful ventilation liberation (adjusted hazard ratio 0.86, 95% CI 0.77–0.95, P = 0.0047). Sensitivity analyses showed similar results.

Conclusions

In a cohort of invasively ventilated patients with COVID-19 and ARDS, a higher cumulative fluid balance was associated with a longer ventilation duration, indicating that restricted fluid management in these patients may be beneficial.

Trial registration Clinicaltrials.gov (NCT04346342); Date of registration: April 15, 2020.

Graphical abstract

Biological impact of restrictive and liberal fluid strategies at low and high PEEP levels on lung and distal organs in experimental acute respiratory distress syndrome

Background: Fluid regimens in acute respiratory distress syndrome (ARDS) are conflicting. The amount of fluid and positive end-expiratory pressure (PEEP) level may interact leading to ventilator-induced lung injury (VILI). We therefore evaluated restrictive and liberal fluid strategies associated with low and high PEEP levels with regard to lung and kidney damage, as well as cardiorespiratory function in endotoxin-induced ARDS.

Methods: Thirty male Wistar rats received an intratracheal instillation of Escherichia coli lipopolysaccharide. After 24 h, the animals were anesthetized, protectively ventilated (V_T = 6 ml/kg), and randomized to restrictive (5 ml/kg/h) or liberal (40 ml/kg/h) fluid strategies (Ringer lactate). Both groups were then ventilated with PEEP = 3 cmH₂O (PEEP3) and PEEP = 9 cmH₂O (PEEP9) for 1 h (n = 6/group). Echocardiography, arterial blood gases, and lung mechanics were evaluated throughout the experiments. Histologic analyses were done on the lungs, and molecular biology was assessed in lungs and kidneys using six non-ventilated animals with no fluid therapy.

Results: In lungs, the liberal group showed increased transpulmonary plateau pressure compared with the restrictive group (liberal, 23.5 ± 2.9 cmH₂O; restrictive, 18.8 ± 2.3 cmH₂O, p = 0.046) under PEEP = 9 cmH₂O. Gene expression associated with inflammation (interleukin [IL]-6) was higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.006) and restrictive-PEEP9 (p = 0.012), Regardless of the fluid strategy, lung mechanical power and the heterogeneity index were higher, whereas birefringence for claudin-4 and zonula-ocludens-1 gene expression were lower in the PEEP9 groups. Perivascular edema was higher in liberal groups, regardless of PEEP levels. Markers related to damage to epithelial cells [club cell secreted protein (CC16)] and the extracellular matrix (syndecan) were higher in the liberal-PEEP9 group than the liberal-PEEP3 group (p = 0.010 and p = 0.024, respectively). In kidneys, the expression of IL-6 and neutrophil gelatinase-associated lipocalin was higher in PEEP9 groups, regardless of the fluid strategy. For the liberal strategy, PEEP = 9 cmH₂O compared with PEEP = 3 cmH₂O reduced the right ventricle systolic volume (37%) and inferior vena cava collapsibility index (45%).

Conclusion: The combination of a liberal fluid strategy and high PEEP led to more lung damage. The application of high PEEP, regardless of the fluid strategy, may also be deleterious to kidneys.

The optimal management of the patient with COVID‐19 pneumonia: HFNC, NIV/CPAP or mechanical ventilation?

The recent pandemic has seen unprecedented demand for respiratory support of patients with COVID‐19 pneumonia, stretching services and clinicians. Yet despite the global numbers of patients treated, guidance is not clear on the correct choice of modality or the timing of escalation of therapy for an individual patient.This narrative review assesses the available literature on the best use of different modalities of respiratory support for an individual patient, and discusses benefits and risks of each, coupled with practical advice to improve outcomes. On current data, in an ideal context, it appears that as disease severity worsens, conventional oxygen therapy is not sufficient alone. In more severe disease, i.e. PaO2/FiO2 ratios below approximately 200, helmet‐CPAP (continuous positive airway pressure) (although not widely available) may be superior to high‐flow nasal cannula (HFNC) therapy or facemask non‐invasive ventilation (NIV)/CPAP, and that facemask NIV/CPAP may be superior to HFNC, but with noted important complications, including risk of pneumothoraces. In an ideal context, invasive mechanical ventilation should not be delayed where indicated and available. Vitally, the choice of respiratory support should not be prescriptive but contextualised to each setting, as supply and demand of resources vary markedly between institutions. Over time, institutions should develop clear policies to guide clinicians before demand exceeds supply, and should frequently review best practice as evidence matures.

Association of Volume Status During Veno-Venous Extracorporeal Membrane Oxygenation with Outcome

Fluid overload in acute respiratory distress syndrome is associated with increased mortality. The purpose of this study was to investigate the association of cumulative fluid balance (CFB) during the first 7 days of veno-venous extracorporeal membrane oxygenation (VV ECMO) and mortality. Adult patients on VV ECMO for greater than 168 hours, between November 2015 and October 2019, were included. CFB during the first 7 ECMO days was compared between survivors and nonsurvivors, and survival was analyzed using Kaplan-Meier analysis and cox proportional hazards modeling. One hundred forty-six patients were included. Median age was 45 years [32, 55], respiratory ECMO survival prediction score was 3 [0, 5], and P/F ratio was 70 [55, 85]. CFB for ECMO days 1-3 was +2,350 cc [-540, 5,941], days 4-7 -3,070 cc [-6,545, 437], and days 1-7 -341 cc [-4,579, 5,290]. One hundred seventeen patients (80%) survived to hospital discharge. Survivors were younger (41 years [31, 53] vs. 53 years [45, 60], p &lt; 0.001) and had a higher respiratory ECMO survival prediction score, (3 [1, 5] vs. 1.5 [-1, 3], p = 0.002). VV ECMO survivors had a significantly more negative CFB during the first 7 days of VV ECMO (-1,311 cc [-4,755, 4,217] vs. 3,617 cc [-2,764, 9,413], p = 0.02), and CFB was an independent predictor of 90 day mortality (HR = 1.07 [1.01, 1.14], p = 0.02). Further studies are needed to determine the causal relationship between fluid balance and survival during VV ECMO.

Loop diuretics in adult intensive care patients with fluid overload: a systematic review of randomised clinical trials with meta-analysis and trial sequential analysis

BACKGROUND

Fluid overload is a risk factor for organ dysfunction and death in intensive care unit (ICU) patients, but no guidelines exist for its management. We systematically reviewed benefits and harms of a single loop diuretic, the predominant treatment used for fluid overload in these patients.

METHODS

We conducted a systematic review with meta-analysis and Trial Sequential Analysis (TSA) of a single loop diuretic vs. other interventions reported in randomised clinical trials, adhering to our published protocol, the Cochrane Handbook, and PRISMA statement. We assessed the risks of bias with the ROB2-tool and certainty of evidence with GRADE. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42020184799).

RESULTS

We included 10 trials (804 participants), all at overall high risk of bias. For loop diuretics vs. placebo/no intervention, we found no difference in all-cause mortality (relative risk (RR) 0.72, 95% confidence interval (CI) 0.49-1.06; 4 trials; 359 participants; I2 = 0%; TSA-adjusted CI 0.15-3.48; very low certainty of evidence). Fewer serious adverse events were registered in the group treated with loop diuretics (RR 0.81, 95% CI 0.66-0.99; 6 trials; 476 participants; I2 = 0%; very low certainty of evidence), though contested by TSA (TSA-adjusted CI 0.55-1.20).

CONCLUSIONS

The evidence is very uncertain about the effect of loop diuretics on mortality and serious adverse events in adult ICU patients with fluid overload. Loop diuretics may reduce the occurrence of these outcomes, but large randomised placebo-controlled trials at low risk of bias are needed.

Pathophysiology, mechanisms, and managements of tissue hypoxia

Oxygen is needed to generate aerobic adenosine triphosphate and energy that is required to support vital cellular functions. Oxygen delivery (DO₂) to the tissues is determined by convective and diffusive processes. The ability of the body to adjust oxygen extraction (ERO₂) in response to changes in DO₂ is crucial to maintain constant tissue oxygen consumption (VO₂). The capability to increase ERO₂ is the result of the regulation of the circulation and the effects of the simultaneous activation of both central and local factors. The endothelium plays a crucial role in matching tissue oxygen supply to demand in situations of acute drop in tissue oxygenation. Tissue oxygenation is adequate when tissue oxygen demand is met. When DO₂ is severely compromised, a critical DO₂ value is reached below which VO₂ falls and becomes dependent on DO₂, resulting in tissue hypoxia. The different mechanisms of tissue hypoxia are circulatory, anaemic, and hypoxic, characterised by a diminished DO₂ but preserved capacity of increasing ERO₂. Cytopathic hypoxia is another mechanism of tissue hypoxia that is due to impairment in mitochondrial respiration that can be observed in septic conditions with normal overall DO₂. Sepsis induces microcirculatory alterations with decreased functional capillary density, increased number of stopped-flow capillaries, and marked heterogeneity between the areas with large intercapillary distance, resulting in impairment of the tissue to extract oxygen and to satisfy the increased tissue oxygen demand, leading to the development of tissue hypoxia. Different therapeutic approaches exist to increase DO₂ and improve microcirculation, such as fluid therapy, transfusion, vasopressors, inotropes, and vasodilators. However, the effects of these agents on microcirculation are quite variable.

Doppler-estimated Carotid and Brachial Artery Flow as Surrogate for Cardiac Output: Needs Further Validation

Selvam V, Srinivasan S. Doppler-estimated Carotid and Brachial Artery Flow as Surrogate for Cardiac Output: Needs Further Validation. Indian J Crit Care Med 2022;26(2):159–160.

Fluid overload in children with pediatric acute respiratory distress syndrome: A retrospective cohort study

OBJECTIVES

To assess the association of cumulative fluid overload (FO) up to 14 days from the diagnosis of pediatric acute respiratory syndrome (PARDS) with pediatric intensive care unit (PICU) mortality, 28-day mechanical ventilation free days (VFD), and 28-day intensive care unit free days (IFD). We hypothesized that fluid overload, even beyond the acute period, would be associated with increased morbidity and mortality.

METHODS

We conducted a retrospective cohort study of PARDS patients admitted to PICU from 2009 to 2015. For repeated admissions, we considered the admission with the highest oxygenation index (OI). Daily FO (%) was calculated as (intake - output)/weight at PICU admission × 100. Peak cumulative FO (CFO) was the highest CFO from the diagnosis of PARDS to Day 14 or to PICU discharge or mortality, whichever was earliest. Rate to peak CFO was the peak CFO divided by the number of days to reach that highest CFO. The association of FO with mortality, VFD and IFD were analyzed with logistic and linear regression models, with the following covariates: Pediatric Index of Mortality 2 score, PARDS severity, and the presence of acute kidney injury (AKI).

RESULTS

There were 165 patients included in this study, with a mortality rate of 45.5% (75/165), median age 3.2 years (interquartile range [IQR] 0.7-9.9) and OI 15.8 (IQR 9.5-27.9). Seventy-three (44.2%) patients had severe PARDS and 64 (38.8%) had AKI. AKI (aOR [adjusted odds ratio] 3.19, 95% CI [confidence interval] 1.43-7.09, p = 0.004) and rate to peak cumulative FO (aOR 1.23, 95% CI 1.07-1.42, p = 0.004) were associated with mortality. AKI and peak cumulative FO were associated with decreased VFD and IFD.

CONCLUSION

The rate to peak CFO over the first 14 days of PARDS was associated with mortality and peak CFO was associated with decreased VFD and IFD.

Euvolemic off pump coronary surgery further improves early postoperative outcomes

Background:

Fluid resuscitation during Off-Pump Coronary Surgery (OPCABG) is still not protocolized and depends on multiple variables. We are exploring in this study whether a restrictive or euvolemic approach has any impact on short term surgical outcomes following OPCABG.

Methods:

It is a retrospective study of 300 patients analyzed based on the intraoperative fluid requirement with 150 patients in each group (Group I: Fluid <2 Litres, Group II: Fluid >2 Litres).

Results:

Multivariable analysis showed echocardiography variables such as E/e ratio, LA volume index, and atrial fibrillation (AF). LA volume index is related to the higher fluid requirement. Group II had significantly higher ventilation time (P < 0.05), drain output (P = 0.05), drain removal time (<0.05), inotropic requirement, and diuretic use.

Conclusion:

The requirement of the intraoperative fluid was associated with various factors including diastolic dysfunction (left atrial volume index, left ventricle mass index, E/e ratio) and preoperative dual antiplatelet use. Group II patients had longer ventilation time, diuretics use, high drain output, and required drains for a longer period of time. Although there was no statistical difference among two groups as far as postoperative AF concerned, a reversal of AF to sinus rhythm was delayed in group II patients.

Current Practice of Fluid Maintenance and Replacement Therapy in Mechanically Ventilated Critically Ill Children: A European Survey

Appropriate fluid management in mechanically ventilated critically ill children remains an important challenge and topic of active discussion in pediatric intensive care medicine. An increasing number of studies show an association between a positive fluid balance or fluid overload and adverse outcomes. However, to date, no international consensus regarding fluid management or removal strategies exists. The aim of this study was to obtain more insight into the current clinical practice of fluid therapy in mechanically ventilated critically ill children. On behalf of the section of cardiovascular dynamics of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) we conducted an anonymous survey among pediatric intensive care unit (PICU) specialists in Europe regarding fluid overload and management. A total of 107 study participants responded to the survey. The vast majority of respondents considers fluid overload to be a common phenomenon in mechanically ventilated children and believes this complication is associated with adverse outcomes, such as mortality and duration of respiratory support. Yet, only 75% of the respondents administers a lower volume of fluids (reduction of 20% of normal intake) to mechanically ventilated critically ill children on admission. During PICU stay, a cumulative fluid balance of more than 5% is considered to be an indication to reduce fluid intake and start diuretic treatment in most respondents. Next to fluid balance calculation, the occurrence of peripheral and/or pulmonary edema (as assessed including by chest radiograph and lung ultrasound) was considered an important clinical sign of fluid overload entailing further therapeutic action. In conclusion, fluid overload in mechanically ventilated critically ill children is considered an important problem among PICU specialists, but there is great heterogeneity in the current clinical practice to avoid this complication. We identify a great need for further prospective and randomized investigation of the effects of (restrictive) fluid strategies in the PICU.

Ventilator-Associated Events: Epidemiology, Risk Factors, and Prevention

The Centers for Disease Control and Prevention shifted the focus of safety surveillance in mechanically ventilated patients from ventilator-associated pneumonia to ventilator-associated events in 2013 to increase the objectivity and reproducibility of surveillance and to encourage quality improvement programs to focus on preventing a broader array of complications. Ventilator-associated events are associated with a doubling of the risk of dying. Prospective studies have found that minimizing sedation, increasing spontaneous awakening and breathing trials, and conservative fluid management can decrease event rates and the duration of ventilation. Multifaceted interventions to enhance these practices can decrease ventilator-associated event rates.

Severe Patients With ARDS With COVID-19 Treated With Extracorporeal Membrane Oxygenation in China: A Retrospective Study

Background: The novel coronavirus disease 2019 (COVID-19) pandemic has become a global health crisis affecting over 200 countries worldwide. Extracorporeal membrane oxygenation (ECMO) has been increasingly used in the management of COVID-19-associated end-stage respiratory failure. However, the exact effect of ECMO in the management of these patients, especially with regards to complications and mortality, is unclear.

Methods: This is the largest retrospective study of ECMO treated COVID-19 patients in China. A total of 50 ECMO-treated COVID-19 patients were recruited. We describe the main characteristics, the clinical features, ventilator parameters, ECMO-related variables and management details, and complications and outcomes of COVID-19 patients with severe acute respiratory distress syndrome (ARDS) that required ECMO support.

Results: For those patients with ECMO support, 21 patients survived and 29 died (mortality rate: 58.0%). Among those who survived, PaO₂ (66.3 mmHg [59.5–74.0 mmHg] and PaO₂/FiO₂ (68.0 mmHg [61.0–76.0 mmHg]) were higher in the survivors than those of non-survivors (PaO₂: 56.8 mmHg (49.0–65.0 mmHg), PaO₂/FiO₂ (58.2 mmHg (49.0–68.0 mmHg), all P < 0.01) prior to ECMO. Patients who achieved negative fluid balance in the early resuscitation phase (within 3 days) had a higher survival rate than those who did not (P = 0.0003).

Conclusions: In this study of 50 cases of ECMO-treated COVID-19 patients, a low PO₂/FIO₂ ratio before ECMO commencement may indicate a poor prognosis. Negative fluid balance in the early resuscitation phase during ECMO treatment was a predictor of increased survival post-ECMO treatment.

Acute Kidney Injury and Acute Respiratory Distress Syndrome

Acute kidney injury (AKI) complicates approximately a third of all acute respiratory distress syndrome (ARDS) cases, and the combination of the two drastically worsens prognosis. Recent advances in ARDS supportive care have led to improved outcomes; however, much less is known on how to prevent and support patients with AKI and ARDS together. Understanding the dynamic relationship between the kidneys and lungs is crucial for the practicing intensivist to prevent injury. This article summarizes key concepts for the critical care physician managing a patient with ARDS complicated by AKI. Also provided is a discussion of AKI in the COVID-19 era.

Ability of short-time low peep challenge to predict fluid responsiveness in mechanically ventilated patients in the intensive care

Short-time low PEEP challenge (SLPC, application of additional 5 cmH₂O PEEP to patients for 30 s) is a novel functional hemodynamic test presented in the literature. We hypothesized that SLPC could predict fluid responsiveness better than stroke volume variation (SVV) in mechanically ventilated intensive care patients. Heart rate, mean arterial pressure, stroke volume index (SVI) and SVV were recorded before SLPC, during SLPC and before and after 500 mL fluid loading. Patients whose SVI increased more than 15% after the fluid loading were defined as fluid responders. Reciever operating characteristics (ROC) curves were generated to evaluate the abilities of the methods to predict fluid responsiveness. Fifty-five patients completed the study. Twenty-five (46%) of them were responders. Decrease percentage in SVI during SLPC (SVIΔ%–SLPC) was 11.6 ± 5.2% and 4.3 ± 2.2% in responders and non-responders, respectively (p < 0.001). A good correlation was found between SVIΔ%–SLPC and percentage change in SVI after fluid loading (r = 0.728, P < 0.001). Areas under the ROC curves (ROC–AUC) of SVIΔ%–SLPC and SVV were 0.951 (95% CI 0.857–0.991) and 0.747 (95% CI 0.611–0.854), respectively. The ROC–AUC of SVIΔ%–SLPC was significantly higher than that of SVV (p = 0.0045). The best cut-off value of SVIΔ%–SLPC was 7.5% with 90% sensitivity and 96% specificity. The percentage change in SVI during SLPC predicts fluid responsiveness in intensive care patients who are ventilated with low tidal volumes; the sensitivity and specificity values are higher than those of SVV.

Early Cumulative Fluid Balance and Outcomes in Pediatric Allogeneic Hematopoietic Cell Transplant Recipients With Acute Respiratory Failure: A Multicenter Study

OBJECTIVES

To evaluate the associations between early cumulative fluid balance (CFB) and outcomes among critically ill pediatric allogeneic hematopoietic cell transplant (HCT) recipients with acute respiratory failure, and determine if these associations vary by treatment with renal replacement therapy (RRT).

METHODS

We performed a secondary analysis of a multicenter retrospective cohort of patients (1mo - 21yrs) post-allogeneic HCT with acute respiratory failure treated with invasive mechanical ventilation (IMV) from 2009 to 2014. Fluid intake and output were measured daily for the first week of IMV (day 0 = day of intubation). The exposure, day 3 CFB (CFB from day 0 through day 3 of IMV), was calculated using the equation [Fluid in - Fluid out] (liters)/[PICU admission weight](kg)*100. We measured the association between day 3 CFB and PICU mortality with logistic regression, and the rate of extubation at 28 and 60 days with competing risk regression (PICU mortality = competing risk).

RESULTS

198 patients were included in the study. Mean % CFB for the cohort was positive on day 0 of IMV, and increased further on days 1-7 of IMV. For each 1% increase in day 3 CFB, the odds of PICU mortality were 3% higher (adjusted odds ratio (aOR) 1.03, 95% CI 1.00-1.07), and the rate of extubation was 3% lower at 28 days (adjusted subdistribution hazard ratio (aSHR) 0.97, 95% CI 0.95-0.98) and 3% lower at 60 days (aSHR 0.97, 95% CI 0.95-0.98). When day 3 CFB was dichotomized, 161 (81%) had positive and 37 (19%) had negative day 3 CFB. Positive day 3 CFB was associated with higher PICU mortality (aOR 3.42, 95% CI 1.48-7.87) and a lower rate of extubation at 28 days (aSHR 0.30, 95% CI 0.18-0.48) and 60 days (aSHR 0.30, 95% 0.19-0.48). On stratified analysis, the association between positive day 3 CFB and PICU mortality was significantly stronger in those not treated with RRT (no RRT: aOR 9.11, 95% CI 2.29-36.22; RRT: aOR 1.40, 95% CI 0.42-4.74).

CONCLUSIONS

Among critically ill pediatric allogeneic HCT recipients with acute respiratory failure, positive and increasing early CFB were independently associated with adverse outcomes.

Helmet and face mask for non-invasive respiratory support in patients with acute hypoxemic respiratory failure: A retrospective study

PURPOSE

Non-invasive respiratory support could reduce the incidence of intubation in patients with Acute Hypoxemic Respiratory Failure (AHRF). The optimal interface or modality of non-invasive respiratory support is debated. We sought to evaluate the differences between patients who succeeded or failed non-invasive respiratory support, with a specific focus on the type of non-invasive respiratory support (i.e. helmet CPAP versus face mask NIV).

MATERIALS AND METHODS

In a single-center observational retrospective study, we investigated baseline, clinical characteristics and AHRF management by non-invasive respiratory support between January 2015 to December 2016. Data on gas exchange and respiratory mechanics, non-invasive respiratory support duration, ICU length of stay and mortality were collected.

RESULTS

110 patients with AHRF were included of which 41 patients (37%) were intubated. The use of helmet CPAP (p = 0.016) and a lower fluid balance (p = 0.038) were independently associated with a decreased rate of intubation after adjustment for confounders. Face mask NIV patients trended to a higher respiratory frequency at 1 h after treatment [28 (22-36) versus 24 (18-29) hours, p = 0.067], and showed a longer ICU stay (p = 0.009) compared to patients treated with helmet CPAP.

CONCLUSIONS

Helmet CPAP and a lower fluid balance were independent predictors of a lower intubation rate in AHRF patients in ICU. Prospective studies aimed at identifying the optimal interface and modality of non-invasive respiratory support in AHRF patients are needed.

Prediction of fluid responsiveness using lung recruitment manoeuvre in paediatric patients receiving lung-protective ventilation: A prospective observational study

BACKGROUND

Pressure-based dynamic variables are poor predictors of fluid responsiveness in children, and their predictability is expected to reduce further during lung-protective ventilation with a low tidal volume.

OBJECTIVE

We hypothesised that lung recruitment manoeuvre (LRM)-induced changes in dynamic variables improve their ability to predict fluid responsiveness in children.

DESIGN

Prospective observational study.

SETTING

Tertiary care children's hospital, single-centre study performed from June 2017 to May 2019.

PATIENTS

We included patients less than 7 years of age undergoing cardiac surgery. Neonates and patients with pulmonary hypertension, significant dysrhythmia, ventricular ejection fraction of less than 30% or pulmonary disease were excluded.

INTERVENTION

All patients were provided with lung-protective volume-controlled ventilation (tidal volume 6 ml kg-1, positive end-expiratory pressure 6 cmH2O). A LRM was applied with a continuous inspiratory pressure of 25 cmH2O for 20 s.

MAIN OUTCOME MEASURE

The ability of dynamic variables to predict fluid responsiveness was evaluated by the area under the receiver operating characteristic curve [area under the curve (AUC)]. Fluid responsiveness was defined as an increase in the cardiac index by more than 15% with crystalloid administration (10 ml kg-1).

RESULTS

Thirty patients were included in the final analysis, of whom 19 were responders. The baseline pleth variability index (PVI) (AUC 0.794, 95% confidence interval 0.608 to 0.919, P < 0.001) and LRM-induced PVI (AUC 0.711, 95% confidence interval 0.517 to 0.861, P = 0.026) could predict fluid responsiveness. The respiratory variation of pulse oximetry photoplethysmographic waveform and pulse pressure variation did not predict fluid responsiveness regardless of the LRM.

CONCLUSION

The PVI is effective in predicting fluid responsiveness in paediatric patients with lung-protective ventilation regardless of a LRM. However, the LRM did not improve the ability of the other dynamic variables to predict fluid responsiveness in these patients.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.gov identifier: NCT03184961.

Impact of Early Fluid Balance on 1-Year Mortality in Critically Ill Patients With Cancer: A Retrospective Study in Central Taiwan

A positive fluid balance has been found to be deleterious in critically ill patients; however, the impact of early fluid balance, particularly on long-term outcomes, in critically ill patients with cancer remains unclear. We performed this retrospective study at a tertiary-care referral hospital with 1500 beds and 6 intensive care units (ICUs) in central Taiwan, and 942 patients with cancer admitted to ICUs during 2013 to 2016 were enrolled. The primary outcome was 1-year mortality. Cancer-related data were obtained from the cancer registry, and data during ICU admissions were retrieved from the electronic medical records. The association between fluid balance, which was represented by median and interquartile range, and 1-year mortality was determined by calculating the hazard ratio (HR) with 95% confidence interval (CI) using a multivariable Cox proportional hazards regression model. The in-hospital mortality rate was 22.9% (216 of 942), and the mortality within 1 year after the index ICU admission was 38.7% (365 of 942). Compared to survivors, nonsurvivors tended to have a higher Acute Physiology and Chronic Health Evaluation II score (24.1 ± 6.9 vs 20.5 ± 6.2, P < .01), a higher age (65.0 ± 14.4 vs 61.3 ± 14.3, P < .01), a higher serum creatinine (1.5 ± 1.3 vs 1.0 ± 1.0, P < .01), and a higher cumulative day 1 to 4 fluid balance (2669, 955-5005 vs 4103, 1268-7215 mL, P < .01). Multivariable Cox proportional hazards regression analysis found that cumulative day-4 fluid balance was independently associated with 1-year mortality (adj HR 1.227, 95% CI: 1.132-1.329). A positive day 1 to 4 cumulative fluid balance was associated with shorter 1-year survival in critically ill patients with cancer. Further studies are needed to validate this association.

A longitudinal change of syndecan-1 predicts risk of acute respiratory distress syndrome and cumulative fluid balance in patients with septic shock: a preliminary study

Background

The purpose of this study is to investigate the time course of syndecan-1 (Syn-1) plasma levels, the correlation between Syn-1 and organ damage development, and the associations of Syn-1 level with cumulative fluid balance and ventilator-free days (VFD) in patients with septic shock.

Methods

We collected blood samples from 38 patients with septic shock upon their admission to ICU and for the first 7 days of their stay. Syn-1 plasma level, acute respiratory distress syndrome (ARDS), other organ damage, VFD, and cumulative fluid balance were assessed daily.

Results

Over the course of 7 days, Syn-1 plasma levels increased significantly more in patients with ARDS than in those without ARDS. Patients with high levels of Syn-1 in the 72 h after ICU admission had significantly higher cumulative fluid balance, lower PaO₂/FiO₂, and fewer VFD than patients with low levels of Syn-1. Syn-1 levels did not correlate with sequential organ failure assessment score or with APACHE II score.

Conclusions

In our cohort of patients with septic shock, higher circulating level of Syn-1 of cardinal glycocalyx component is associated with more ARDS, cumulative positive fluid balance, and fewer VFD. Measurement of Syn-1 levels in patients with septic shock might be useful for predicting patients at high risk of ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40560-021-00543-x.

Association between Cumulative Fluid Balance and Outcomes in Acute Respiratory Distress Syndrome Patients Treated with Extracorporeal Membrane Oxygenation

Background

Extracorporeal membrane oxygenation (ECMO) has become increasingly accepted as a life-saving procedure for patients with severe acute respiratory distress syndrome (ARDS). This study investigated the relationship between cumulative fluid balance (CFB) and outcomes in adult ARDS patients treated with ECMO.

Methods

We retrospectively analyzed the data of adult ARDS patients who received ECMO between December 2009 and December 2019 at Korea University Anam Hospital. CFB was calculated during the first 7 days after ECMO initiation. The primary endpoint was 28-day mortality.

Results

The 74 patients were divided into survivor (n=33) and non-survivor (n=41) groups based on 28-day survival. Non-survivors showed a significantly higher CFB at 1-7 days (p<0.05). Cox multivariable proportional hazard regression revealed a relationship between CFB on day 3 and 28-day mortality (hazard ratio, 3.366; 95% confidence interval, 1.528-7.417; p=0.003).

Conclusion

In adult ARDS patients treated with ECMO, a higher positive CFB on day 3 was associated with increased 28-day mortality. Based on our findings, we suggest a restrictive fluid strategy in ARDS patients treated with ECMO. CFB may be a useful predictor of survival in ARDS patients treated with ECMO.

Inferior vena cava dilation predicts global cardiac dysfunction in acute respiratory distress syndrome: A strain echocardiographic study

PURPOSE

Limited data exist on the utility of ultrasonographic evaluation of inferior vena cava (IVC) in acute respiratory distress syndrome (ARDS). We studied the value of IVC diameter in assessing cardio-circulatory performance in ARDS using strain echocardiography.

MATERIALS AND METHODS

Retrospective cross-sectional analysis of Doppler echocardiograms of patients with moderate-severe ARDS was performed. Right ventricle (RV) parameters, IVC diameter, and left ventricle (LV) systolic and diastolic parameters were collected. RV free wall strain (RVFWS) and LV global longitudinal strain (LVGLS) were calculated.

RESULTS

Fifty-one patients were dichotomized into two groups: with IVC > 2.1 cm (dilated) and with IVC ≤ 2.1 cm (nondilated). The dilated IVC group presented worse hypoxemic profile, hypotension, and poor perfusion markers. No significant associations with positive end-expiratory pressure or lung mechanics were observed. Dilated IVC was associated with impaired RV function, high central venous pressure, elevated pulmonary artery pressure, and LV systolic and diastolic dysfunctions. Strongest predictors of a dilated IVC were RVFWS, LVGLS, and tissue Doppler mitral annular early diastolic velocity. Dilated IVC predicted a global cardiac dysfunction defined by strain echocardiography (GCDS) with high sensitivity and specificity.

CONCLUSIONS

In ARDS, strain echocardiography analyses demonstrated that a dilated IVC is associated with GCDS and impaired hemodynamics independent of lung mechanics. A dilated IVC should be considered a marker of circulatory distress, signaling the potential necessity for improved hemodynamic optimization.

Association of Fluid Balance and Survival of Pediatric Patients Treated With Extracorporeal Membrane Oxygenation

The effect of positive fluid balance (FB) on extracorporeal membrane oxygenation (ECMO) outcomes in pediatric patients remains unknown. We sought to evaluate if positive FB in pediatric intensive care unit (PICU) patients with respiratory and/or cardiac failure necessitating ECMO was associated with increased morbidity or mortality. This was a multicenter retrospective cohort study of data from the deidentified PEDiatric ECMO Outcomes Registry (PEDECOR). Patients entered into the database from 2014 to 2017, who received ECMO support, were included. A total of 168 subjects met the study criteria. Univariate analysis showed no significant difference in total FB on ECMO days 1-5 between survivors and non-survivors [median 90 ml/kg (IQR 18-208.5) for survivors vs. median 139.7 ml/kg (IQR 11.2-300.6) for non-survivors, p = 0.334]. There was also no difference in total FB on ECMO days 1-5 in patients with no change in functional outcome as reflected by the Pediatric Outcome Performance Category (POPC) score vs. those who had worsening in POPC score ≥2 at hospital discharge [median 98 ml/kg (IQR 18-267) vs. median 130 ml/kg (IQR 13-252), p = 0.91]. Subjects that required 50 ml/kg or more of blood products over the initial 5 days of ECMO support had an increased rate of mortality with an odds ratio of 5.8 (95% confidence interval of 2.7-12.3; p = 0.048). Our study showed no association of the noted FB with survival after ECMO cannulation. This FB trend was also not associated with POPC at hospital discharge, MV duration, or ECMO duration. The amount of blood product administered was found to be a significant predictor of mortality.

Fluid Responsiveness in the Critically Ill Patient

Accurate assessment of intravascular volume status in critically ill patients remains a very challenging task. Recent data have shown adverse outcomes in critically ill patients with either inadequate or overaggressive fluid therapy. Understanding the tools and techniques available for accurate volume assessment is imperative. This article discusses the concept of fluid responsiveness and reviews methods for assessing fluid responsiveness in critically ill patients.

Comparison of the Efficacy of Different Arterial Waveform-derived Variables (Pulse Pressure Variation, Stroke Volume Variation, Systolic Pressure Variation) for Fluid Responsiveness in Hemodynamically Unstable Mechanically Ventilated Critically Ill Patients

Introduction

This study was conducted to assess fluid responsiveness in critically ill patients to avoid various complications of fluid overload.

Material and methods

This study was done in an ICU of a tertiary care hospital after approval from the institute ethical committee over 18 months. A total of 54 consenting adult patients were included in the study. Patients were hemodynamically unstable requiring mechanical ventilation, had acute circulatory failure, or those with at least one clinical sign of inadequate tissue perfusion. All patients were ventilated using tidal volume of 6–8 mL/kg, RR—12–15/minutes, positive end expiratory pressure (PEEP)—5 cm of water, and plateau pressure was kept below 30 cm water. They were sedated throughout the study. The arterial line and the central venous catheter were placed and connected to Vigileo-FloTrac transducer (Edward Lifesciences). Patients were classified into responder and nonresponder groups on the basis of the cardiac index (CI) after fluid challenge of 10 mL/kg of normal saline over 30 minutes. Pulse pressure variation (PPV), stroke volume variation (SVV), and systolic pressure variation (SPV) were assessed and compared at baseline, 30 minutes, and 60 minutes.

Results

In our study we found that PPV and SVV were significantly lower among responders than nonresponders at 30 minutes and insignificant at 60 minutes. Stroke volume variation was 10.28 ± 1.76 in the responder compared to 12.28 ± 4.42 (p = 0.02) at 30 minutes and PPV was 15.28 ± 6.94 in responders while it was 20.03 ± 4.35 in nonresponders (p = 0.01). We found SPV was insignificant at all time periods among both groups.

Conclusion

We can conclude that initial assessment for fluid responsiveness in critically ill mechanically ventilated patients should be based on PPV and SVV to prevent complications of fluid overload and their consequences.

How to cite this article

Kumar N, Malviya D, Nath SS, Rastogi S, Upadhyay V. Comparison of the Efficacy of Different Arterial Waveform-derived Variables (Pulse Pressure Variation, Stroke Volume Variation, Systolic Pressure Variation) for Fluid Responsiveness in Hemodynamically Unstable Mechanically Ventilated Critically Ill Patients. Indian J Crit Care Med 2021;25(1):48–53.

COVID-19-associated acute respiratory distress syndrome (CARDS): Current knowledge on pathophysiology and ICU treatment - A narrative review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces coronavirus-19 disease (COVID-19) and is a major health concern. Following two SARS-CoV-2 pandemic “waves,” intensive care unit (ICU) specialists are treating a large number of COVID19-associated acute respiratory distress syndrome (ARDS) patients. From a pathophysiological perspective, prominent mechanisms of COVID19-associated ARDS (CARDS) include severe pulmonary infiltration/edema and inflammation leading to impaired alveolar homeostasis, alteration of pulmonary physiology resulting in pulmonary fibrosis, endothelial inflammation (endotheliitis), vascular thrombosis, and immune cell activation.

Although the syndrome ARDS serves as an umbrella term, distinct, i.e., CARDS-specific pathomechanisms and comorbidities can be noted (e.g., virus-induced endotheliitis associated with thromboembolism) and some aspects of CARDS can be considered ARDS “atypical.” Importantly, specific evidence-based medical interventions for CARDS (with the potential exception of corticosteroid use) are currently unavailable, limiting treatment efforts to mostly supportive ICU care.

In this article, we will discuss the underlying pulmonary pathophysiology and the clinical management of CARDS. In addition, we will outline current and potential future treatment approaches.

Implementing a Goal-Directed Therapy Protocol for Fluid Resuscitation in the Cardiovascular Intensive Care Unit

BACKGROUND

Balancing fluid administration and titration of vasoactive medications is critical to preventing postoperative complications in cardiac surgical patients.

OBJECTIVE

To evaluate the impact of implementing a goal-directed therapy protocol in the cardiovascular intensive care unit on total intravenous fluids administered on the day of surgery, rates of acute kidney injury, and hospital length of stay.

METHODS

A fluid resuscitation protocol using dynamic assessment of fluid responsiveness with stroke volume index was developed, and nurses were prepared for its implementation using simulation training.

RESULTS

After implementation of the new protocol, the total amount of intravenous fluids administered on the day of surgery was significantly reduced (P = .003). There were no significant changes in hospital length of stay (P = .83) or rates of acute kidney injury (P = .86). There were significant increases in nurses' knowledge of (P < .001) and confidence in (P < .001) fluid resuscitation and titration of vasoactive medications after simulation training.

CONCLUSIONS

Use of a fluid resuscitation protocol resulted in a reduction in the amount of intravenous fluids administered on the day of surgery. The simulation training increased nurses' knowledge of and confidence in fluid resuscitation and titration of vasoactive medications.

Fluid administration and monitoring in ARDS: which management?

Modalities of fluid management in patients sustaining the acute respiratory distress syndrome (ARDS) are challenging and controversial. Optimal fluid management should provide adequate oxygen delivery to the body, while avoiding inadvertent increase in lung edema which further impairs gas exchange. In ARDS patients, positive fluid balance has been associated with prolonged mechanical ventilation, longer ICU and hospital stay, and higher mortality. Accordingly, a restrictive strategy has been compared to a more liberal approach in randomized controlled trials conducted in various clinical settings. Restrictive strategies included fluid restriction guided by the monitoring of extravascular lung water, pulmonary capillary wedge or central venous pressure, and furosemide targeted to diuresis and/or albumin replacement in hypoproteinemic patients. Overall, restrictive strategies improved oxygenation significantly and reduced duration of mechanical ventilation, but had no significant effect on mortality. Fluid management may require different approaches depending on the time course of ARDS (i.e., early vs. late period). The effects of fluid strategy management according to ARDS phenotypes remain to be evaluated. Since ARDS is frequently associated with sepsis-induced acute circulatory failure, the prediction of fluid responsiveness is crucial in these patients to avoid hemodynamically inefficient—hence respiratory detrimental—fluid administration. Specific hemodynamic indices of fluid responsiveness or mini-fluid challenges should be preferably used. Since the positive airway pressure contributes to positive fluid balance in ventilated ARDS patients, it should be kept as low as possible. As soon as the hemodynamic status is stabilized, correction of cumulated fluid retention may rely on diuretics administration or renal replacement therapy.

The inspiration hold maneuver is a reliable method to assess mean systemic filling pressure but its clinical value remains unclear

Background

The upstream pressure for venous return (VR) is considered to be a combined conceptual blood pressure of the systemic vessels: the mean systemic filling pressure (MSFP). The relevance of estimating the MSFP during dynamic changes of the circulation at the bedside is controversial. Herein, we studied the effect of high ventilatory pressures on the relationship between VR and central venous pressure (CVP).

Methods

In 9 healthy pigs under anaesthesia and mechanically ventilated, MSFP was estimated from extrapolated VR versus CVP relationships during inspiratory hold maneuvers (IHMs) with different levels of ventilatory pressure (Pvent). MSFP was measure 3 times per animal during euvolemia and hypovolemia. Hypovolemia was induced by bleeding with 10 mL/kg. The estimated MSFP values were compared to the blood pressure recording after induced ventricle fibrillation (i.e., mean circulatory filling pressure).

Results

Our results revealed a strong linear correlation between VR and CVP [R2 of 0.92 (range, 0.67–0.99)], during IHMs with different levels of Pvent. Volume status significantly alters the resulting MSFP, 20±1 and 16±2 mmHg for euvolemia and hypovolemia respectively. This estimation of the MSFP was strongly correlated—but not interchangeable—to the blood pressure recording after induced ventricle fibrillation (R2=0.8 and P=0.045).

Conclusions

In conclusion, we showed a strong linear correlation between VR and CVP—when applying IHMs with high levels of Pvent—however the clinical applicability of this method to guide volume therapy in its current form is improbable.

Hypotheses about sub-optimal hydration in the weeks before coronavirus disease (COVID-19) as a risk factor for dying from COVID-19

To address urgent need for strategies to limit mortality from coronavirus disease 2019 (COVID-19), this review describes experimental, clinical and epidemiological evidence that suggests that chronic sub-optimal hydration in the weeks before infection might increase risk of COVID-19 mortality in multiple ways. Sub-optimal hydration is associated with key risk factors for COVID-19 mortality, including older age, male sex, race-ethnicity and chronic disease. Chronic hypertonicity, total body water deficit and/or hypovolemia cause multiple intracellular and/or physiologic adaptations that preferentially retain body water and favor positive total body water balance when challenged by infection. Via effects on serum/glucocorticoid-regulated kinase 1 (SGK1) signaling, aldosterone, tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), aquaporin 5 (AQP5) and/or Na⁺/K⁺-ATPase, chronic sub-optimal hydration in the weeks before exposure to COVID-19 may conceivably result in: greater abundance of angiotensin converting enzyme 2 (ACE2) receptors in the lung, which increases likelihood of COVID-19 infection, lung epithelial cells which are pre-set for exaggerated immune response, increased capacity for capillary leakage of fluid into the airway space, and/or reduced capacity for both passive and active transport of fluid out of the airways. The hypothesized hydration effects suggest hypotheses regarding strategies for COVID-19 risk reduction, such as public health recommendations to increase intake of drinking water, hydration screening alongside COVID-19 testing, and treatment tailored to the pre-infection hydration condition. Hydration may link risk factors and pathways in a unified mechanism for COVID-19 mortality. Attention to hydration holds potential to reduce COVID-19 mortality and disparities via at least 5 pathways simultaneously.

Early fluid overload is associated with mortality and prolonged mechanical ventilation in extremely low birth weight infants

Recent studies revealed that fluid overload is associated with higher mortality in critically ill children and adults. This study aimed to evaluate the association between fluid overload in the first 3 days of life and mortality in extremely low birth weight infants. This single-center retrospective cohort study included two hundred nineteen newborns with birth weight less than 1000 g who were admitted to the neonatal intensive care between January 2012 and December 2017. Overall mortality was 32.4%, the median gestational age was 27.3 (26.1-29.4) weeks, and birth weight was 770 (610-900) grams. In the group with severe fluid overload, we found a higher rate of deaths (72.2%); mean airway pressure was significantly higher and with longer invasive mechanical ventilation necessity.Conclusion: Early fluid overload in extremely low birth weight infants is associated with higher mortality rate, higher mean airway pressure in invasive mechanically ventilated patients, and longer mechanical ventilation duration in the first 7 days of life. What is Known: • Fluid overload is associated with a higher mortality rate and prolonged mechanical ventilation in children and adults. What is New: • Fluid overload in the first 72 h of life in an extremely premature infant is associated with higher mortality rate, higher mean airway pressure in invasive mechanically ventilated patients, and longer mechanical ventilation duration the first 7 days of life.