Parameters of fluid responsiveness:

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

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

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.

Consistency of data reporting in fluid responsiveness studies in the critically ill setting: the CODEFIRE consensus from the Cardiovascular Dynamic section of the European Society of Intensive Care Medicine

PURPOSE

To provide consensus recommendations regarding hemodynamic data reporting in studies investigating fluid responsiveness and fluid challenge (FC) use in the intensive care unit (ICU).

METHODS

The Executive Committee of the European Society of Intensive Care Medicine (ESICM) commissioned and supervised the project. A panel of 18 international experts and a methodologist identified main domains and items from a systematic literature, plus 2 ancillary domains. A three-step Delphi process based on an iterative approach was used to obtain the final consensus. In the Delphi 1 and 2, the items were selected with strong (≥ 80% of votes) or week agreement (70-80% of votes), while the Delphi 3 generated recommended (≥ 90% of votes) or suggested (80-90% of votes) items (RI and SI, respectively).

RESULTS

We identified 5 main domains initially including 117 items and the consensus finally resulted in 52 recommendations or suggestions: 18 RIs and 2 SIs statements were obtained for the domain "ICU admission", 11 RIs and 1 SI for the domain "mechanical ventilation", 5 RIs for the domain "reason for giving a FC", 8 RIs for the domain pre- and post-FC "hemodynamic data", and 7 RIs for the domain "pre-FC infused drugs". We had no consensus on the use of echocardiography, strong agreement regarding the volume (4 ml/kg) and the reference variable (cardiac output), while weak on administration rate (within 10 min) of FC in this setting.

CONCLUSION

This consensus found 5 main domains and provided 52 recommendations for data reporting in studies investigating fluid responsiveness in ICU patients.

Comparison Between Changes in Systolic-Pressure Variation and Pulse-Pressure Variation After Passive Leg Raising to Predict Fluid Responsiveness in Postoperative Critically Ill Patients

OBJECTIVE

The authors aimed to evaluate the precision of changes in systolic-pressure variation after passive leg raising (PLR) as a predictor of fluid responsiveness in postoperative critically ill patients, and to compare the precision of changes in pulse-pressure variation after PLR (ΔPPVPLR) with changes in systolic-pressure variation after PLR (ΔSPVPLR).

DESIGN

A prospective observational study.

SETTING

A surgical intensive care unit of a tertiary hospital.

PARTICIPANTS

Seventy-four postoperative critically ill patients with acute circulatory failure were enrolled.

INTERVENTIONS

Fluid responsiveness was defined as an increase of 10% or more in stroke volume after PLR, dividing patients into 2 groups: responders and nonresponders.

MEASUREMENT AND MAIN RESULTS

Hemodynamic data were recorded at baseline and after PLR, and the stroke volume was measured by transthoracic echocardiography. Thirty-eight patients were responders, and 36 were nonresponders. ΔPPVPLR predicted fluid responsiveness with an area under the receiver operating characteristic curve (AUC) of 0.917, and the optimal cutoff value was 2.3%, with a gray zone of 1.6% to 3.3%, including 19 (25.7%) patients. ΔSPVPLR predicted fluid responsiveness with an AUC of 0.908, and the optimal cutoff value was 1.9%, with a gray zone of 1.1% to 2.0%, including 18 (24.3%) patients. No notable distinction was observed between the AUC for ΔPPVPLR and ΔSPVPLR (p = 0.805) in predicting fluid responsiveness.

CONCLUSIONS

ΔSPVPLR and ΔPPVPLR could accurately predict fluid responsiveness in postoperative critically ill patients. There was no difference in the ability to predict fluid responsiveness between ΔSPVPLR and ΔPPVPLR.

Surviving Sepsis After Burn Campaign

INTRODUCTION

The Surviving Sepsis Campaign was developed to improve outcomes for all patients with sepsis. Despite sepsis being the primary cause of death after thermal injury, burns have always been excluded from the Surviving Sepsis efforts. To improve sepsis outcomes in burn patients, an international group of burn experts developed the Surviving Sepsis After Burn Campaign (SSABC) as a testable guideline to improve burn sepsis outcomes.

METHODS

The International Society for Burn Injuries (ISBI) reached out to regional or national burn organizations to recommend members to participate in the program. Two members of the ISBI developed specific "patient/population, intervention, comparison and outcome" (PICO) questions that paralleled the 2021 Surviving Sepsis Campaign [1]. SSABC participants were asked to search the current literature and rate its quality for each topic. At the Congress of the ISBI, in Guadalajara, Mexico, August 28, 2022, a majority of the participants met to create "statements" based on the literature. The "summary statements" were then sent to all members for comment with the hope of developing an 80% consensus. After four reviews, a consensus statement for each topic was created or "no consensus" was reported.

RESULTS

The committee developed sixty statements within fourteen topics that provide guidance for the early treatment of sepsis in burn patients. These statements should be used to improve the care of sepsis in burn patients. The statements should not be considered as "static" comments but should rather be used as guidelines for future testing of the best treatments for sepsis in burn patients. They should be updated on a regular basis.

CONCLUSION

Members of the burn community from the around the world have developed the Surviving Sepsis After Burn Campaign guidelines with the goal of improving the outcome of sepsis in burn patients.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSION

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

PASSIVE LEG RAISING-INDUCED CHANGES IN PEAK VELOCITY VARIATION OF LEFT VENTRICULAR OUTFLOW TRACT TO PREDICT FLUID RESPONSIVENESS IN POSTOPERATIVE CRITICALLY ILL ELDERLY PATIENTS

ABSTRACT

Background : Accurate prediction of fluid responsiveness is important for postoperative critically ill elderly patients. The objective of this study was to evaluate the predictive values of peak velocity variation (ΔVpeak) and passive leg raising (PLR)-induced changes in ΔVpeak (ΔVpeak PLR ) of the left ventricular outflow tract to predict fluid responsiveness in postoperative critically ill elderly patients. Method : Seventy-two postoperative elderly patients with acute circulatory failure who were mechanically ventilated with sinus rhythm were enrolled in our study. Pulse pressure variation (PPV), ΔVpeak, and stroke volume were collected at baseline and after PLR. An increase of >10% in stroke volume after PLR defined fluid responsiveness. Receiver operating characteristic curves and gray zones were constructed to assess the ability of ΔVpeak and ΔVpeak PLR to predict fluid responsiveness. Results : Thirty-two patients were fluid responders. The area under the receiver operating characteristic curves (AUC) for baseline PPV and ΔVpeak to predict fluid responsiveness was 0.768 (95% confidence interval [CI], 0.653-0.859; P < 0.001) and 0.899 (95% CI, 0.805-0.958; P < 0.001) with gray zones of 7.63% to 12.66% that included 41 patients (56.9%) and 9.92% to 13.46% that included 28 patients (38.9%). ΔPPV PLR predicted fluid responsiveness with an AUC of 0.909 (95% CI, 0.818-0.964; P < 0.001), and the gray zone was 1.49% to 2.93% and included 20 patients (27.8%). ΔVpeak PLR predicted fluid responsiveness with an AUC of 0.944 (95% CI, 0.863-0.984; P < 0.001), and the gray zone was 1.48% to 2.46% and included six patients (8.3%). Conclusions : Passive leg raising-induced changes in peak velocity variation of blood flow in the left ventricular outflow tract accurately predicted fluid responsiveness with a small gray zone in postoperative critically ill elderly patients.

Changes of cardiac output and velocity time integral in blood return at the end of renal replacement therapy predict fluid responsiveness in critically Ill patients with acute circulatory failure

OBJECTIVES

To observe if blood return, also defined as the blood infusion test (BIT) could predict fluid responsiveness in critically ill patients with acute circulatory failure and renal replacement therapy (RRT).

METHODS

This was a single-center, prospective, diagnostic accuracy study. Before BIT, the passive leg raise test (PLRT) was performed to record the change of cardiac output (ΔCO) by pulse contour analysis, and ΔCO >  = 10% was defined as the fluid responder. Meanwhile, the change in velocity time integral (ΔVTI) was recorded by ultrasound. Later, the ΔCO and ΔVTI during BIT were recorded 5-10 min after PLRT. The receiver-operating characteristic curves of ΔCO and ΔVTI of BIT were performed in predicting the fluid responder defined by PLRT.

RESULTS

A total of 43 patients with acute circulatory failure undergoing RRT were enrolled in the present study, and 25 patients (58.1%) were recognized as responders during PLRT. According to the receiver-operating characteristic curves, the cutoff value of ΔCO was 10% and ΔVTI was 9% during BIT with the area under curve of 0.96 and 0.94, respectively.

CONCLUSIONS

BIT in RRT could identify fluid responsiveness in critically ill patients with shock.

TRIAL REGISTRATION

ChiCTR-DDD-17010534. Registered on 30/01/2017 (retrospective registration).

Tidal volume challenge to predict preload responsiveness in patients with acute respiratory distress syndrome under prone position

Background

Prone position is frequently used in patients with acute respiratory distress syndrome (ARDS), especially during the Coronavirus disease 2019 pandemic. Our study investigated the ability of pulse pressure variation (PPV) and its changes during a tidal volume challenge (TVC) to assess preload responsiveness in ARDS patients under prone position.

Methods

This was a prospective study conducted in a 25-bed intensive care unit at a university hospital. We included patients with ARDS under prone position, ventilated with 6 mL/kg tidal volume and monitored by a transpulmonary thermodilution device. We measured PPV and its changes during a TVC (ΔPPV TVC6–8) after increasing the tidal volume from 6 to 8 mL/kg for one minute. Changes in cardiac index (CI) during a Trendelenburg maneuver (ΔCITREND) and during end-expiratory occlusion (EEO) at 8 mL/kg tidal volume (ΔCI EEO8) were recorded. Preload responsiveness was defined by both ΔCITREND ≥ 8% and ΔCI EEO8 ≥ 5%. Preload unresponsiveness was defined by both ΔCITREND < 8% and ΔCI EEO8 < 5%.

Results

Eighty-four sets of measurements were analyzed in 58 patients. Before prone positioning, the ratio of partial pressure of arterial oxygen to fraction of inspired oxygen was 104 ± 27 mmHg. At the inclusion time, patients were under prone position for 11 (2–14) hours. Norepinephrine was administered in 83% of cases with a dose of 0.25 (0.15–0.42) µg/kg/min. The positive end-expiratory pressure was 14 (11–16) cmH2O. The driving pressure was 12 (10–17) cmH2O, and the respiratory system compliance was 32 (22–40) mL/cmH2O. Preload responsiveness was detected in 42 cases. An absolute change in PPV ≥ 3.5% during a TVC assessed preload responsiveness with an area under the receiver operating characteristics (AUROC) curve of 0.94 ± 0.03 (sensitivity: 98%, specificity: 86%) better than that of baseline PPV (0.85 ± 0.05; p = 0.047). In the 56 cases where baseline PPV was inconclusive (≥ 4% and < 11%), ΔPPV TVC6–8 ≥ 3.5% still enabled to reliably assess preload responsiveness (AUROC: 0.91 ± 0.05, sensitivity: 97%, specificity: 81%; p < 0.01 vs. baseline PPV).

Conclusion

In patients with ARDS under low tidal volume ventilation during prone position, the changes in PPV during a TVC can reliably assess preload responsiveness without the need for cardiac output measurements.

Trial registration: ClinicalTrials.gov (NCT04457739). Registered 30 June 2020 —Retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT04457739

ISCCM Guidelines for Hemodynamic Monitoring in the Critically Ill

Hemodynamic assessment along with continuous monitoring and appropriate therapy forms an integral part of management of critically ill patients with acute circulatory failure. In India, the infrastructure in ICUs varies from very basic facilities in smaller towns and semi-urban areas, to world-class, cutting-edge technology in corporate hospitals, in metropolitan cities. Surveys and studies from India suggest a wide variation in clinical practices due to possible lack of awareness, expertise, high costs, and lack of availability of advanced hemodynamic monitoring devices. We, therefore, on behalf of the Indian Society of Critical Care Medicine (ISCCM), formulated these evidence-based guidelines for optimal use of various hemodynamic monitoring modalities keeping in mind the resource-limited settings and the specific needs of our patients. When enough evidence was not forthcoming, we have made recommendations after achieving consensus amongst members. Careful integration of clinical assessment and critical information obtained from laboratory data and monitoring devices should help in improving outcomes of our patients.

How to cite this article

Kulkarni AP, Govil D, Samavedam S, Srinivasan S, Ramasubban S, Venkataraman R, et al. ISCCM Guidelines for Hemodynamic Monitoring in the Critically Ill. Indian J Crit Care Med 2022;26(S2):S66-S76.

Intravenous fluid therapy in perioperative and critical care setting-Knowledge test and practice: An international cross-sectional survey

PURPOSE

In the absence of recent international recommendations supported by scientific societies like Anesthesiology or Intensive Care Medicine, healthcare professionals (HCP) knowledge on IV fluid is expected to vary. We undertook a cross-sectional survey, aiming to assess prescription patterns and test the knowledge of HCP for IV fluid use in the operating room (OR) and intensive care unit (ICU).

METHODS

An online international cross-sectional survey was conducted between October 20, 2019, and November 27, 2021. The survey included multiple-choice questions on demographics, practice patterns and knowledge of IV fluids, and a hemodynamically unstable patient assessment.

RESULTS

1045 HCP, from 97 countries responded to the survey. Nearly three-quarters reported the non-existence of internal hospital or ICU-based guidelines on IV fluids. The respondents' mean score on the knowledge assessment questions was 46.4 ± 14.4. The cumulative mean scores were significantly higher among those supervising trainees (p = 0.02), specialists (p < 0.001) and those working in high-income (p < 0.001) countries. Overall performance of respondents on the knowledge testing for IV fluid was unsatisfactory with only 6.5% respondents performed above average.

CONCLUSION

There is a wide difference in the knowledge and prescription of IV fluids among the HCP surveyed. These findings reflect the urgent need for education on IV fluids.

Septic Shock and Cardiac Arrest in Obstetrics: A Practical Simplified Clinical View

Septic shock and cardiac arrest during pregnancy, despite being uncommon, carry a high mortality rate among pregnant individuals. Basic initial management strategies are fundamental to improve clinical outcomes; obstetricians and maternal-fetal medicine specialists need to be familiar with such interventions.

The Cardiac Caval Index: Improving Noninvasive Assessment of Cardiac Preload

OBJECTIVES

Inferior vena cava (IVC) pulsatility quantified by the Caval Index (CI) is characterized by poor reliability, also due to the irregular magnitude of spontaneous respiratory activity generating the major pulsatile component. The aim of this study was to test whether the IVC cardiac oscillatory component could provide a more stable index (Cardiac CI-CCI) compared to CI or respiratory CI (RCI).

METHODS

Nine healthy volunteers underwent long-term monitoring in supine position of IVC, followed by 3 minutes passive leg raising (PLR). CI, RCI, and CCI were extracted from video recordings by automated edge-tracking and CCI was averaged over each respiratory cycle (aCCI). Cardiac output (CO), mean arterial pressure (MAP) and heart rate (HR) were also recorded during baseline (1 minutes prior to PLR) and PLR (first minute).

RESULTS

In response to PLR, all IVC indices decreased (P < .01), CO increased by 4 ± 4% (P = .055) while HR and MAP did not vary. The Coefficient of Variation (CoV) of aCCI (13 ± 5%) was lower than that of CI (17 ± 5%, P < .01), RCI (26 ± 7%, P < .001) and CCI (25 ± 7%, P < .001). The mutual correlations in time of the indices were 0.81 (CI-RCI), 0.49 (CI-aCCI) and 0.2 (RCI-aCCI).

CONCLUSIONS

Long-term IVC monitoring by automated edge-tracking allowed us to evidence that 1) respiratory and averaged cardiac pulsatility components are uncorrelated and thus carry different information and 2) the new index aCCI, exhibiting the lowest CoV while maintaining good sensitivity to blood volume changes, may overcome the poor reliability of CI and RCI.

Prediction of fluid responsiveness. What’s new?

Although the administration of fluid is the first treatment considered in almost all cases of circulatory failure, this therapeutic option poses two essential problems: the increase in cardiac output induced by a bolus of fluid is inconstant, and the deleterious effects of fluid overload are now clearly demonstrated. This is why many tests and indices have been developed to detect preload dependence and predict fluid responsiveness. In this review, we take stock of the data published in the field over the past three years. Regarding the passive leg raising test, we detail the different stroke volume surrogates that have recently been described to measure its effects using minimally invasive and easily accessible methods. We review the limits of the test, especially in patients with intra-abdominal hypertension. Regarding the end-expiratory occlusion test, we also present recent investigations that have sought to measure its effects without an invasive measurement of cardiac output. Although the limits of interpretation of the respiratory variation of pulse pressure and of the diameter of the vena cava during mechanical ventilation are now well known, several recent studies have shown how changes in pulse pressure variation itself during other tests reflect simultaneous changes in cardiac output, allowing these tests to be carried out without its direct measurement. This is particularly the case during the tidal volume challenge, a relatively recent test whose reliability is increasingly well established. The mini-fluid challenge has the advantage of being easy to perform, but it requires direct measurement of cardiac output, like the classic fluid challenge. Initially described with echocardiography, recent studies have investigated other means of judging its effects. We highlight the problem of their precision, which is necessary to evidence small changes in cardiac output. Finally, we point out other tests that have appeared more recently, such as the Trendelenburg manoeuvre, a potentially interesting alternative for patients in the prone position.

Assessment of Dynamic Changes in Stressed Volume and Venous Return during Hyperdynamic Septic Shock

The present work investigated the dynamic changes in stressed volume (Vs) and other determinants of venous return using a porcine model of hyperdynamic septic shock. Septicemia was induced in 10 anesthetized swine, and fluid challenges were started after the diagnosis of sepsis-induced arterial hypotension and/or tissue hypoperfusion. Norepinephrine infusion targeting a mean arterial pressure (MAP) of 65 mmHg was started after three consecutive fluid challenges. After septic shock was confirmed, norepinephrine infusion was discontinued, and the animals were left untreated until cardiac arrest occurred. Baseline Vs decreased by 7% for each mmHg decrease in MAP during progression of septic shock. Mean circulatory filling pressure (Pmcf) analogue (Pmca), right atrial pressure, resistance to venous return, and efficiency of the heart decreased with time (p < 0.001 for all). Fluid challenges did not improve hemodynamics, but noradrenaline increased Vs from 107 mL to 257 mL (140%) and MAP from 45 mmHg to 66 mmHg (47%). Baseline Pmca and post-cardiac arrest Pmcf did not differ significantly (14.3 ± 1.23 mmHg vs. 14.75 ± 1.5 mmHg, p = 0.24), but the difference between pre-arrest Pmca and post-cardiac arrest Pmcf was statistically significant (9.5 ± 0.57 mmHg vs. 14.75 ± 1.5 mmHg, p < 0.001). In conclusion, the baseline Vs decreased by 7% for each mmHg decrease in MAP during progression of hyperdynamic septic shock. Significant changes were also observed in other determinants of venous return. A new physiological intravascular volume existing at zero transmural distending pressure was identified, termed as the rest volume (Vr).

Respiratory-Cardiovascular Interactions During Mechanical Ventilation: Physiology and Clinical Implications

Positive-pressure inspiration and positive end-expiratory pressure (PEEP) increase pleural, alveolar, lung transmural, and intra-abdominal pressure, which decrease right and left ventricular (RV; LV) preload and LV afterload and increase RV afterload. The magnitude and clinical significance of the resulting changes in ventricular function are determined by the delivered tidal volume, the total level of PEEP, the compliance of the lungs and chest wall, intravascular volume, baseline RV and LV function, and intra-abdominal pressure. In mechanically ventilated patients, the most important, adverse consequences of respiratory-cardiovascular interactions are a PEEP-induced reduction in cardiac output, systemic oxygen delivery, and blood pressure; RV dysfunction in patients with ARDS; and acute hemodynamic collapse in patients with pulmonary hypertension. On the other hand, the hemodynamic changes produced by respiratory-cardiovascular interactions can be beneficial when used to assess volume responsiveness in hypotensive patients and by reducing dyspnea and improving hypoxemia in patients with cardiogenic pulmonary edema. Thus, a thorough understanding of the physiological principles underlying respiratory-cardiovascular interactions is essential if critical care practitioners are to anticipate, recognize, manage, and utilize their hemodynamic effects. © 2022 American Physiological Society. Compr Physiol 12:1-24, 2022.

[Resuscitation strategy for patients with sepsis and septic shock]

Fluid and vasopressor resuscitation is, along with antimicrobial therapy and control of the focus of infection, a basic issue of the treatment of sepsis and septic shock. There is currently no accepted protocol that we can follow for the resuscitation of these patients and the Surviving Sepsis Campaign proposes controversial measures and without sufficient evidence support to establish firm recommendations. We propose a resuscitation strategy adapted to the situation of each patient: in the patient in whom community sepsis is suspected, we consider that the early administration of 30mL/kg of crystalloids is effective and safe; in the patient with nosocomial sepsis, we must carry out a more in-depth evaluation before initiating aggressive resuscitation. In patients who do not respond to initial resuscitation, it is necessary to increase monitoring level and, depending on the hemodynamic profile, administer more fluids, a second vasopressor or inotropes.

Predictive Value of the Respiratory Variation in Inferior Vena Cava Diameter for Ventilated Children With Septic Shock

OBJECTIVES

This study aimed to investigate the predictive utility of respiratory variations of inferior vena cava diameters on fluid responsiveness in children with septic shock.

DESIGN

A prospective observational single-center study.

SETTING

A pediatric intensive care unit in a tertiary hospital in China.

PARTICIPANTS

Patients with sepsis shock who require invasive mechanical ventilation were recruited between 1 December 2017 and 1 November 2021.

INTERVENTIONS AND MEASUREMENTS

Volume expansion (VE) was induced by a 30-min infusion of 20 ml/kg of normal saline. Hemodynamics indexes were obtained through bedside transthoracic echocardiography (TTE) measurement and calculation.

RESULTS

A total of 86 patients were enrolled in this study, among them, 45 patients (52.3%) were considered to be non-responders (NR), with an increase in stroke volume variation (SVV) <15% after VE. Multivariate logistic analysis showed that ΔIVC (adjusted OR = 1.615, 95% CI 1.092-2.215, p = 0.012) was the significant predictor associated with the fluid responsiveness. The area under the ROC of ΔIVC was 0.922 (95% CI: 0.829-1.000, p < 0.01), and the cutoff value of ΔIVC used to predict fluid responsiveness was 28.5%, with a sensitivity and specificity of 95.4 and 68.5%, respectively.

CONCLUSIONS

The ΔIVC was found to have a potential value in predicting fluid responsiveness in mechanically ventilated children with septic shock.

Hemodynamic effects of different fluid volumes for a fluid challenge in septic shock patients

Background:

It is still unclear what the minimal infusion volume is to effectively predict fluid responsiveness. This study was designed to explore the minimal infusion volume to effectively predict fluid responsiveness in septic shock patients. Hemodynamic effects of fluid administration on arterial load were observed and added values of effective arterial elastance (Ea) in fluid resuscitation were assessed.

Methods:

Intensive care unit septic shock patients with indwelling pulmonary artery catheter (PAC) received five sequential intravenous boluses of 100 mL 4% gelatin. Cardiac output (CO) was measured with PAC before and after each bolus. Fluid responsiveness was defined as an increase in CO >10% after 500 mL fluid infusion.

Results:

Forty-seven patients were included and 35 (74.5%) patients were fluid responders. CO increasing >5.2% after a 200 mL fluid challenge (FC) provided an improved detection of fluid responsiveness, with a specificity of 80.0% and a sensitivity of 91.7%. The area under the ROC curve (AUC) was 0.93 (95% CI: 0.84–1.00, P < 0.001). Fluid administration induced a decrease in Ea from 2.23 (1.46–2.78) mmHg/mL to 1.83 (1.34–2.44) mmHg/mL (P = 0.002), especially for fluid responders in whom arterial pressure did not increase. Notably, the baseline Ea was able to detect the fluid responsiveness with an AUC of 0.74 (95% CI: 0.59–0.86, P < 0.001), whereas Ea failed to predict the pressure response to FC with an AUC of 0.50 (95% CI: 0.33–0.67, P = 0.086).

Conclusion:

In septic shock patients, a minimal volume of 200 mL 4% gelatin could reliably detect fluid responders. Fluid administration reduced Ea even when CO increased. The loss of arterial load might be the reason for patients who increased their CO without pressure responsiveness. Moreover, a high level of Ea before FC was able to predict fluid responsiveness rather than to detect the pressure responsiveness.

Trial registration:

ClinicalTrials.gov, NCT04515511

Current practice and evolving concepts in septic shock resuscitation

Clinical and pathophysiological understanding of septic shock has progressed exponentially in the previous decades, translating into a steady decrease in septic shock-related morbidity and mortality. Even though large randomized, controlled trials have addressed fundamental aspects of septic shock resuscitation, many questions still exist. In this review, we will describe the current standards of septic shock resuscitation, but the emphasis will be placed on evolving concepts in different domains such as clinical resuscitation targets, adequate use of fluids and vasoactive drugs, refractory shock, and the use of extracorporeal therapies. Multiple research opportunities remain open, and collaborative endeavors should be performed to fill in these gaps.

Accuracy of cumulative volumes of fluid challenge to assess fluid responsiveness in critically ill patients with acute circulatory failure: a pharmacodynamic approach

BACKGROUND

The relationship between the dose (volume of fluid) and the effect (increase of stroke volume [SV]) has been poorly described. We hypothesised that the analysis of the dynamic response of SV during fluid challenge (FC) helps to determine the optimal volume of FC, along with its diagnostic accuracy parameters for fluid responsiveness.

METHODS

A prospective observational study was conducted in critically ill patients with circulatory failure. Patients monitored with oesophageal Doppler and assigned to an FC of 500 ml of crystalloid were included. The areas under the curve (AUC) and 95% confidence intervals (CI₉₅) of the receiver operating characteristic curves for cumulative volumes from 50 to 450 ml were determined for fluid responsiveness (SV increase ≥15% from baseline) along with other parameters of diagnostic accuracy. In the pharmacodynamic analysis, dose-effect and dose-response models were constructed, with determination of median and 90% effective dose (ED₅₀ and ED₉₀).

RESULTS

Forty-five patients were included. The AUC increased with cumulative volumes of FC up to 250 ml (AUC₂₅₀ 0.93 [CI₉₅: 0.85-1.00]), followed by a plateau above 0.95 of AUC. The optimal volume was 250 ml, associated with a specificity of 0.89 [CI₉₅: 0.78-1.00], a sensitivity of 0.92 [CI₉₅: 0.69-1.00], and a threshold of 9.6% increase in SV. The ED₅₀ was 156 [CI₉₅: 136-177] ml and the ED₉₀ was 312 [CI₉₅: 269-352] ml.

CONCLUSIONS

A volume of FC of 250 ml with a threshold of 9.6% increase in SV showed the highest accuracy in detecting fluid responsiveness in critically ill patients with shock.

CLINICAL TRIAL REGISTRATION

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Volume status and volume responsiveness in postoperative cardiac surgical patients: An observational, multicentre cohort study

BACKGROUND

The best strategy to identify patients in whom fluid loading increases cardiac output (CO) following cardiac surgery remains debated. This study examined the utility of a calculated mean systemic filling pressure analogue (P_msa ) and derived variables to explain the response to a fluid bolus.

METHODS

The P_msa was calculated using retrospective, observational cohort data in the early postoperative period between admission to the intensive care unit and extubation within 6 hours. The venous return pressure gradient (VRdP) was calculated as P_msa  - central venous pressure. Concurrent changes induced by a fluid bolus in the ratio of the VRdP over P_msa , the volume efficiency (E_vol ), were studied to assess fluid responsiveness. Changes between P_msa and derived variables and CO were analysed by Wilcoxon rank-sum test, hierarchial clustering and multiple linear regression.

RESULTS

Data were analysed for 235 patients who received 489 fluid boluses. The P_msa increased with consecutive fluid boluses (median difference [range] 1.3 [0.5-2.4] mm Hg, P = .03) with a corresponding increase in VRdP (median difference 0.4 [0.2-0.6] mm Hg, P = .04). Hierarchical cluster analysis only identified E_vol and the change in CO within one cluster. The multiple linear regression between P_msa and its derived variables and the change in CO (overall r²  = .48, P < .001) demonstrated the best partial regression between the continuous change in CO and the concurrent E_vol (r = .55, P < .001).

CONCLUSION

The mean systemic filling P_msa enabled a comprehensive interpretation of fluid responsiveness with volume efficiency useful to explain the change in CO as a continuous phenomenon.

The ability of pulse oximetry-derived peripheral perfusion index to detect fluid responsiveness in patients with septic shock

BACKGROUND

Fluid challenge test is a widely used method for the detection of fluid responsiveness in acute circulatory failure. However, detection of the patient's response to the fluid challenge requires monitoring of cardiac output which is not feasible in many settings. We investigated whether the changes in the pulse oximetry-derived peripheral perfusion index (PPI), as a non-invasive surrogate of cardiac output, can detect fluid responsiveness using the fluid challenge test or not.

METHODS

We prospectively enrolled 58 patients with septic shock on norepinephrine infusion. Fluid challenge test, using 200 mL crystalloid solution, was performed in all study subjects. All patients received an additional 300 mL crystalloid infusion to confirm fluid responsiveness. Velocity time integral (VTI) (using transthoracic echocardiography), and PPI were measured at the baseline, after 200 mL fluid challenge, and after completion of 500 mL crystalloids. Fluid responsiveness was defined by 10% increase in the VTI after completion of the 500 mL. The predictive ability of ∆PPI [Calculated as (PPI after 200 mL - baseline PPI)/baseline PPI] to detect fluid responders was obtained using the receiver operating characteristic curve.

RESULTS

Forty-two patients (74%) were fluid responders; in whom, the mean arterial pressure, the central venous pressure, the VTI, and the PPI increased after fluid administration compared to the baseline values. ∆PPI showed moderate ability to detect fluid responders [area under receiver operating characteristic curve (95% confidence interval) 0.82 (0.70-0.91), sensitivity 76%, specificity 80%, positive predictive value 92%, negative predictive value 54%, cutoff value ≥ 5%]. There was a significant correlation between ∆PPI and ∆VTI induced by the fluid challenge.

CONCLUSION

∆PPI showed moderate ability to detect fluid responsiveness in patients with septic shock on norepinephrine infusion. Increased PPI after 200 mL crystalloid challenge can detect fluid responsiveness with a positive predictive value of 92%; however, failure of the PPI to increase does not exclude fluid responsiveness.

CLINICAL TRIAL IDENTIFIER

NCT03805321. Date of registration: 15 January 2019. Clinical trial registration URL: https://clinicaltrials.gov/ct2/show/NCT03805321?term=ahmed+hasanin&rank=9 .

USER Protocol as a Guide to Resuscitation of the Patient with Septic Shock in the Emergency Department

Introduction

Sepsis is a disease that is still associated with high mortality, in which timely interventions are related to better results.

Objective

To determine if there is a difference in in-hospital mortality, fluid balances, norepinephrine initiation and recovery time of blood pressure, when comparing the resuscitation of the patient who is admitted to the emergency room in septic shock by applying the ultrasound protocol (USER) versus the standard of care.

Patients and Methods

This is a prospective, cohort study conducted in the emergency room of a highly complex hospital of patients with septic shock.

Results

83 patients recruited in total. The groups were comparable in demographics, mean baseline blood pressure, disease severity given by the SOFA value, and arterial lactate. A statistically significant difference was documented in the fluid balances at 4 hours, median 1325mL (IQR:451–2455mL) in Group C versus 900mL (IQR:440–1292) in Group U (p=0.048) and at 6 hours, median 1658mL (IQR:610–2925mL) versus 1107mL (IQR:600–1500mL), p=0.026, as well as in the total fluid balance of hospital stay, median 14,564mL (IQR:8660–18,705mL) versus 8660mL (IQR:5309–16,974mL), p=0.049. On the other hand, in the USER Group, the mean blood pressure ≥ 65mmHg was achieved in 97.4% of the patients 4 hours after the start of the protocol versus 50% in Group C (p=<0.001). Mortality with the use of the protocol compared with conventional therapy was (56.4% vs 61.36%, p=0.647).

Conclusion

The use of the USER protocol in patients with septic shock in the emergency room showed lower fluid balances at 4 and 6 hours, and of the total hospital stay, as well as earlier initiation of norepinephrine and statistically significant faster improvement in blood pressure. Although a statistically significant difference was not found in the days of ICU stay, hospitalization and in-hospital mortality, a trend was observed in the reduction of these parameters.

Evaluation of fluid responsiveness during COVID-19 pandemic: what are the remaining choices?

Non-protocolized fluid administration in critically ill patients, especially those with acute respiratory distress syndrome (ARDS), is associated with poor outcomes. Therefore, fluid administration in patients with Coronavirus disease (COVID-19) should be properly guided. Choice of an index to guide fluid management during a pandemic with mass patient admissions carries an additional challenge due to the relatively limited resources. An ideal test for assessment of fluid responsiveness during this pandemic should be accurate in ARDS patients, economic, easy to interpret by junior staff, valid in patients in the prone position and performed with minimal contact with the patient to avoid spread of infection. Patients with COVID-19 ARDS are divided into two phenotypes (L phenotype and H phenotype) according to their lung compliance. Selection of the proper index for fluid responsiveness varies according to the patient phenotype. Heart–lung interaction methods can be used only in patients with L phenotype ARDS. Real-time measures, such a pulse pressure variation, are more appropriate for use during this pandemic compared to ultrasound-derived measures, because contamination of the ultrasound machine can spread infection. Preload challenge tests are suitable for use in all COVID-19 patients. Passive leg raising test is relatively better than mini-fluid challenge test, because it can be repeated without overloading the patient with fluids. Trendelenburg maneuver is a suitable alternative to the passive leg raising test in patients with prone position. If a cardiac output monitor was not available, the response to the passive leg raising test could be traced by measurement of the pulse pressure or the perfusion index. Preload modifying maneuvers, such as tidal volume challenge, can also be used in COVID-19 patients, especially if the patient was in the gray zone of other dynamic tests. However, the preload modifying maneuvers were not extensively evaluated outside the operating room. Selection of the proper test would vary according to the level of healthcare in the country and the load of admissions which might be overwhelming. Evaluation of the volume status should be comprehensive; therefore, the presence of signs of volume overload such as lower limb edema, lung edema, and severe hypoxemia should be considered beside the usual indices for fluid responsiveness.