The end-expiratory occlusion test: please, let me hold your breath!

Haemodynamic monitoring during noncardiac surgery: past, present, and future

During surgery, various haemodynamic variables are monitored and optimised to maintain organ perfusion pressure and oxygen delivery - and to eventually improve outcomes. Important haemodynamic variables that provide an understanding of most pathophysiologic haemodynamic conditions during surgery include heart rate, arterial pressure, central venous pressure, pulse pressure variation/stroke volume variation, stroke volume, and cardiac output. A basic physiologic and pathophysiologic understanding of these haemodynamic variables and the corresponding monitoring methods is essential. We therefore revisit the pathophysiologic rationale for intraoperative monitoring of haemodynamic variables, describe the history, current use, and future technological developments of monitoring methods, and finally briefly summarise the evidence that haemodynamic management can improve patient-centred outcomes.

Variables influencing the prediction of fluid responsiveness: a systematic review and meta-analysis

INTRODUCTION

Prediction of fluid responsiveness in acutely ill patients might be influenced by a number of clinical and technical factors. We aim to identify variables potentially modifying the operative performance of fluid responsiveness predictors commonly used in clinical practice.

METHODS

A sensitive strategy was conducted in the Medline and Embase databases to search for prospective studies assessing the operative performance of pulse pressure variation, stroke volume variation, passive leg raising (PLR), end-expiratory occlusion test (EEOT), mini-fluid challenge, and tidal volume challenge to predict fluid responsiveness in critically ill and acutely ill surgical patients published between January 1999 and February 2023. Adjusted diagnostic odds ratios (DORs) were calculated by subgroup analyses (inverse variance method) and meta-regression (test of moderators). Variables potentially modifying the operative performance of such predictor tests were classified as technical and clinical.

RESULTS

A total of 149 studies were included in the analysis. The volume used during fluid loading, the method used to assess variations in macrovascular flow (cardiac output, stroke volume, aortic blood flow, volume‒time integral, etc.) in response to PLR/EEOT, and the apneic time selected during the EEOT were identified as technical variables modifying the operative performance of such fluid responsiveness predictor tests (p < 0.05 for all adjusted vs. unadjusted DORs). In addition, the operative performance of fluid responsiveness predictors was also influenced by clinical variables such as the positive end-expiratory pressure (in the case of EEOT) and the dose of norepinephrine used during the fluid responsiveness assessment for PLR and EEOT (for all adjusted vs. unadjusted DORs).

CONCLUSION

Prediction of fluid responsiveness in critically and acutely ill patients is strongly influenced by a number of technical and clinical aspects. Such factors should be considered for individual intervention decisions.

Understanding cardiopulmonary interactions through esophageal pressure monitoring

Esophageal pressure is the closest estimate of pleural pressure. Changes in esophageal pressure reflect changes in intrathoracic pressure and affect transpulmonary pressure, both of which have multiple effects on right and left ventricular performance. During passive breathing, increasing esophageal pressure is associated with lower venous return and higher right ventricular afterload and lower left ventricular afterload and oxygen consumption. In spontaneously breathing patients, negative pleural pressure swings increase venous return, while right heart afterload increases as in passive conditions; for the left ventricle, end-diastolic pressure is increased potentially favoring lung edema. Esophageal pressure monitoring represents a simple bedside method to estimate changes in pleural pressure and can advance our understanding of the cardiovascular performance of critically ill patients undergoing passive or assisted ventilation and guide physiologically personalized treatments.

Predictors of fluid responsiveness in the operating room: a narrative review

Prediction of fluid responsiveness has been considered an essential tool for modern fluid management. However, most studies in this field have focused on patients in intensive care unit despite numerous research throughout several decades. Therefore, the present narrative review aims to show the representative method's feasibility, advantages, and limitations in predicting fluid responsiveness, focusing on the operating room environments. Firstly, we described the predictors of fluid responsiveness based on heart-lung interaction, including pulse pressure and stroke volume variations, the measurement of respiratory variations of inferior vena cava diameter, and the end-expiratory occlusion test and addressed their limitations. Subsequently, the passive leg raising test and mini-fluid challenge tests were also mentioned, which assess fluid responsiveness by mimicking a classic fluid challenge. In the last part of this review, we pointed out the pitfalls of fluid management based on fluid responsiveness prediction, which emphasized the importance of individualized decision-making. Understanding the available representative methods to predict fluid responsiveness and their associated benefits and drawbacks through this review will aid anesthesiologists in choosing the most reliable methods for optimal fluid administration in each patient during anesthesia in the operating room.

Can carotid artery Doppler variations induced by the end-expiratory occlusion maneuver predict fluid responsiveness in septic shock patients?

BACKGROUND

An increase in cardiac index (CI) during an end-expiratory occlusion test (EEOt) predicts fluid responsiveness in ventilated patients. However, if CI monitoring is unavailable or the echocardiographic window is difficult, using the carotid Doppler (CD) could be a feasible alternative to track CI changes. This study investigates whether changes in CD peak velocity (CDPV) and corrected flow time (cFT) during an EEOt were correlated with CI changes and if CDPV and cFT changes predicted fluid responsiveness in patients with septic shock.

METHODS

Prospective, single-center study in adults with hemodynamic instability. The CDPV and cFT on carotid artery Doppler and hemodynamic variables from the pulse contour analysis EV1000™ were recorded at baseline, during a 20-s EEOt, and after fluid challenge (500 mL). We defined responders as those who increased CI ≥ 15% after a fluid challenge.

RESULTS

We performed 44 measurements in 18 mechanically ventilated patients with septic shock and without arrhythmias. The fluid responsiveness rate was 43.2%. The changes in CDPV were significantly correlated with changes in CI during EEOt (r = 0.51 [0.26-0.71]). A significant, albeit lower correlation, was found for cFT (r = 0.35 [0.1-0.58]). An increase in CI ≥ 5.35% during EEOt predicted fluid responsiveness with 78.9% sensitivity and 91.7% specificity, with an area under the ROC curve (AUROC) of 0.85. An increase in CDPV ≥ 10.5% during an EEOt predicted fluid responsiveness with 96.2% specificity and 53.0% sensitivity with an AUROC of 0.74. Sixty-one percent of CDPV measurements (from - 13.5 to 9.5 cm/s) fell within the gray zone. The cFT changes during EEOt did not accurately predict fluid responsiveness.

CONCLUSIONS

In septic shock patients without arrhythmias, an increase in CDPV greater than 10.5% during a 20-s EEOt predicted fluid responsiveness with > 95% specificity. Carotid Doppler combined with EEOt may help optimize preload when invasive hemodynamic monitoring is unavailable. However, the 61% gray zone is a major limitation (retrospectively registered on Clinicaltrials.gov NCT04470856 on July 14, 2020).

The increase in cardiac output induced by a decrease in positive end-expiratory pressure reliably detects volume responsiveness: the PEEP-test study

BACKGROUND

In patients on mechanical ventilation, positive end-expiratory pressure (PEEP) can decrease cardiac output through a decrease in cardiac preload and/or an increase in right ventricular afterload. Increase in central blood volume by fluid administration or passive leg raising (PLR) may reverse these phenomena through an increase in cardiac preload and/or a reopening of closed lung microvessels. We hypothesized that a transient decrease in PEEP (PEEP-test) may be used as a test to detect volume responsiveness.

METHODS

Mechanically ventilated patients with PEEP ≥ 10 cmH₂O ("high level") and without spontaneous breathing were prospectively included. Volume responsiveness was assessed by a positive PLR-test, defined as an increase in pulse-contour-derived cardiac index (CI) during PLR ≥ 10%. The PEEP-test consisted in reducing PEEP from the high level to 5 cmH₂O for one minute. Pulse-contour-derived CI (PiCCO2) was monitored during PLR and the PEEP-test.

RESULTS

We enrolled 64 patients among whom 31 were volume responsive. The median increase in CI during PLR was 14% (11-16%). The median PEEP at baseline was 12 (10-15) cmH₂O and the PEEP-test resulted in a median decrease in PEEP of 7 (5-10) cmH₂O, without difference between volume responsive and unresponsive patients. Among volume responsive patients, the PEEP-test induced a significant increase in CI of 16% (12-20%) (from 2.4 ± 0.7 to 2.9 ± 0.9 L/min/m², p < 0.0001) in comparison with volume unresponsive patients. In volume unresponsive patients, PLR and the PEEP-test increased CI by 2% (1-5%) and 6% (3-8%), respectively. Volume responsiveness was predicted by an increase in CI > 8.6% during the PEEP-test with a sensitivity of 96.8% (95% confidence interval (95%CI): 83.3-99.9%) and a specificity of 84.9% (95%CI 68.1-94.9%). The area under the receiver operating characteristic curve of the PEEP-test for detecting volume responsiveness was 0.94 (95%CI 0.85-0.98) (p < 0.0001 vs. 0.5). Spearman's correlation coefficient between the changes in CI induced by PLR and the PEEP-test was 0.76 (95%CI 0.63-0.85, p < 0.0001).

CONCLUSIONS

A CI increase > 8.6% during a PEEP-test, which consists in reducing PEEP to 5 cmH₂O, reliably detects volume responsiveness in mechanically ventilated patients with a PEEP ≥ 10 cmH₂O. Trial registration ClinicalTrial.gov (NCT 04,023,786). Registered July 18, 2019. Ethics Committee approval CPP Est III (N° 2018-A01599-46).

Prediction of Fluid Responsiveness Using Combined End-Expiratory and End-Inspiratory Occlusion Tests in Cardiac Surgical Patients

End-expiratory occlusion (EEO) and end-inspiratory occlusion (EIO) tests have been successfully used to predict fluid responsiveness in various settings using calibrated pulse contour analysis and echocardiography. The aim of this study was to test if respiratory occlusion tests predicted fluid responsiveness reliably in cardiac surgical patients with protective ventilation. This single-centre, prospective study, included 57 ventilated patients after elective coronary artery bypass grafting who were indicated for fluid expansion. Baseline echocardiographic measurements were obtained and patients with significant cardiac pathology were excluded. Cardiac index (CI), stroke volume and stroke volume variation were recorded using uncalibrated pulse contour analysis at baseline, after performing EEO and EIO tests and after volume expansion (7 mL/kg of succinylated gelatin). Fluid responsiveness was defined as an increase in cardiac index by 15%. Neither EEO, EIO nor their combination predicted fluid responsiveness reliably in our study. After a combined EEO and EIO, a cut-off point for CI change of 16.7% predicted fluid responsiveness with a sensitivity of 61.8%, specificity of 69.6% and ROC AUC of 0.593. In elective cardiac surgical patients with protective ventilation, respiratory occlusion tests failed to predict fluid responsiveness using uncalibrated pulse contour analysis.

How I personalize fluid therapy in septic shock?

During septic shock, fluid therapy is aimed at increasing cardiac output and improving tissue oxygenation, but it poses two problems: it has inconsistent and transient efficacy, and it has many well-documented deleterious effects. We suggest that there is a place for its personalization according to the patient characteristics and the clinical situation, at all stages of circulatory failure. Regarding the choice of fluid for volume expansion, isotonic saline induces hyperchloremic acidosis, but only for very large volumes administered. We suggest that balanced solutions should be reserved for patients who have already received large volumes and in whom the chloremia is rising. The initial volume expansion, intended to compensate for the constant hypovolaemia in the initial phase of septic shock, cannot be adapted to the patient's weight only, as suggested by the Surviving Sepsis Campaign, but should also consider potential absolute hypovolemia induced by fluid losses. After the initial fluid infusion, preload responsiveness may rapidly disappear, and it should be assessed. The choice between tests used for this purpose depends on the presence or absence of mechanical ventilation, the monitoring in place and the risk of fluid accumulation. In non-intubated patients, the passive leg raising test and the mini-fluid challenge are suitable. In patients without cardiac output monitoring, tests like the tidal volume challenge, the passive leg raising test and the mini-fluid challenge can be used as they can be performed by measuring changes in pulse pressure variation, assessed through an arterial line. The mini-fluid challenge should not be repeated in patients who already received large volumes of fluids. The variables to assess fluid accumulation depend on the clinical condition. In acute respiratory distress syndrome, pulmonary arterial occlusion pressure, extravascular lung water and pulmonary vascular permeability index assess the risk of worsening alveolar oedema better than arterial oxygenation. In case of abdominal problems, the intra-abdominal pressure should be taken into account. Finally, fluid depletion in the de-escalation phase is considered in patients with significant fluid accumulation. Fluid removal can be guided by preload responsiveness testing, since haemodynamic deterioration is likely to occur in patients with a preload dependent state.

Hemodynamic Implications of Prone Positioning in Patients with ARDS

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2023. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2023 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

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

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.

[Haemodynamic monitoring in sepsis and septic shock]

Cardiovascular disturbances associated with sepsis cause hypoperfusion situations, which will negatively impact these patients' prognosis. The aim of haemodynamic monitoring is to guide the detection and correction of this hypoperfusion, and assist in decision making in optimising oxygen transport to tissues, primarily by manipulating cardiac output. This review seeks to summarise the different parameters of haemodynamic monitoring, the objectives of resuscitation, the physiological parameters, and the tools available to us for appropriate cardiac output manipulation.

Assessing Fluid Intolerance with Doppler Ultrasonography: A Physiological Framework

Ultrasonography is becoming the favored hemodynamic monitoring utensil of emergentologists, anesthesiologists and intensivists. While the roles of ultrasound grow and evolve, many clinical applications of ultrasound stem from qualitative, image-based protocols, especially for diagnosing and managing circulatory failure. Often, these algorithms imply or suggest treatment. For example, intravenous fluids are opted for or against based upon ultrasonographic signs of preload and estimation of the left ventricular ejection fraction. Though appealing, image-based algorithms skirt some foundational tenets of cardiac physiology; namely, (1) the relationship between cardiac filling and stroke volume varies considerably in the critically ill, (2) the correlation between cardiac filling and total vascular volume is poor and (3) the ejection fraction is not purely an appraisal of cardiac function but rather a measure of coupling between the ventricle and the arterial load. Therefore, management decisions could be enhanced by quantitative approaches, enabled by Doppler ultrasonography. Both fluid ‘responsiveness’ and ‘tolerance’ are evaluated by Doppler ultrasound, but the physiological relationship between these constructs is nebulous. Accordingly, it is argued that the link between them is founded upon the Frank–Starling–Sarnoff relationship and that this framework helps direct future ultrasound protocols, explains seemingly discordant findings and steers new routes of enquiry.

Predicting fluid-response, the heart of hemodynamic management: A model-based solution

BACKGROUND

Intravenous fluid infusions are an important therapy for patients with circulatory shock. However, it is challenging to predict how patients' cardiac stroke volume (SV) will respond, and thus identify how much fluids should be delivered, if any. Model-predicted SV time-profiles of response to fluid infusions could potentially be used to guide fluid therapy.

METHOD

A clinically applicable model-based method predicts SV changes in response to fluid-infusions for a pig trial (N = 6). Validation/calibration SV, SVmea, is from an aortic flow probe. Model parameters are identified in 3 ways: fitting to SVmea from the entire infusion, SVflfit, from the first 200 ml, SVfl200, or from the first 100 ml, SVfl100. RMSE compares error of model-based SV time-profiles for each parameter identification method, and polar plot analysis assesses trending ability. Receiver-operating characteristic (ROC) analysis evaluates ability of model-predicted SVs, SVfl200 and SVfl100, to distinguish non-responsive and responsive infusions, using area-under the curve (AUC), and balanced accuracy as a measure of performance.

RESULTS

RMSE for SVflFit, SVfl200, and SVfl100 was 1.8, 3.2, and 6.5 ml, respectively, and polar plot angular limit of agreement from was 11.6, 28.0, and 68.8°, respectively. For predicting responsive and non-responsive interventions SVfl200, and SVfl100 had ROC AUC of 0.64 and 0.69, respectively, and balanced accuracy was 0.75 in both cases.

CONCLUSIONS

The model-predicted SV time-profiles matched measured SV trends well for SVflFit, SVfl200, but not SVfl100. Thus, the model can fit the observed SV dynamics, and can deliver good SV prediction given a sufficient parameter identification period. This trial is limited by small numbers and provides proof-of-method, with further experimental and clinical investigation needed. Potentially, this method could deliver model-predicted SV time-profiles to guide fluid therapy decisions, or as part of a closed-loop fluid control system.

Management of sepsis and septic shock in the emergency department

Early management of sepsis and septic shock is crucial for patients' prognosis. As the Emergency Department (ED) is the place where the first medical contact for septic patients is likely to occur, emergency physicians play an essential role in the early phases of patient management, which consists of accurate initial diagnosis, resuscitation, and early antibiotic treatment. Since the issuing of the Surviving Sepsis Campaign guidelines in 2016, several studies have been published on different aspects of sepsis management, adding a substantial amount of new information on the pathophysiology and treatment of sepsis and septic shock. In light of this emerging evidence, the present narrative review provides a comprehensive account of the recent advances in septic patient management in the ED.

Bioreactance reliably detects preload responsiveness by the end-expiratory occlusion test when averaging and refresh times are shortened

Background

The end-expiratory occlusion (EEXPO) test detects preload responsiveness, but it is 15 s long and induces small changes in cardiac index (CI). It is doubtful whether the Starling bioreactance device, which averages CI over 24 s and refreshes the displayed value every 4 s (Starling-24.4), can detect the EEXPO-induced changes in CI (ΔCI). Our primary goal was to test whether this Starling device version detects preload responsiveness through EEXPO. We also tested whether shortening the averaging and refresh times to 8 s and one second, respectively, (Starling-8.1) improves the accuracy of the device in detecting preload responsiveness using EEXPO.

Methods

In 42 mechanically ventilated patients, during a 15-s EEXPO, we measured ∆CI through calibrated pulse contour analysis (CI_pulse, PiCCO2 device) and using the Starling device. For the latter, we considered both CI_{Starling-24.4} from the commercial version and CI_Starling-8.1 derived from the raw data. For relative ∆CI_{Starling-24.4} and ∆CI_Starling-8.1 during EEXPO, we calculated the area under the receiver operating characteristic curve (AUROC) to detect preload responsiveness, defined as an increase in CI_pulse ≥ 10% during passive leg raising (PLR). For both methods, the correlation coefficient vs. ∆CI_pulse was calculated.

Results

Twenty-six patients were preload responders and sixteen non preload-responders. The AUROC for ∆CI_{Starling-24.4} was significantly lower compared to ∆CI_Starling-8.1 (0.680 ± 0.086 vs. 0.899 ± 0.049, respectively; p = 0.027). A significant correlation was observed between ∆CI_Starling-8.1 and ∆CI_pulse (r = 0.42; p = 0.009), but not between ∆CI_{Starling-24.4} and ∆CI_pulse. During PLR, both ∆CI_{Starling-24.4} and ∆CI_Starling-8.1 reliably detected preload responsiveness.

Conclusions

Shortening the averaging and refresh times of the bioreactance signal to 8 s and one second, respectively, increases the reliability of the Starling device in detection of EEXPO-induced ∆CI.

Trial registration: No. IDRCB:2018-A02825-50. Registered 13 December 2018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00920-7.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members.As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

Changes in peripheral perfusion index during intraoperative end-expiratory occlusion tests do not predict the response to fluid administration in patients undergoing lung protective ventilation

INTRODUCTION

The end-expiratory occlusion test (EEOT) may predict the response to fluid administration in patients undergoing lung-protective ventilation, but arterial catheter insertion is necessary to evaluate changes in stroke volume (SV). The peripheral perfusion index is a potential noninvasive alternative to evaluate SV. The aim of this study is to investigate whether changes in perfusion index during an intraoperative EEOT can predict the response to fluid administration in patients undergoing lung-protective ventilation (tidal volume 7 ml/kg predicted body weight).

METHODS

Forty-one elective surgical patients were enrolled. The SV and perfusion index were recorded before (baseline), during a 40-s EEOT and after volume expansion (250 ml of lactated Ringer's solution over 10 min). Patients with an increase in SV greater than 10% after volume expansion were defined as responders. ΔPI (change in perfusion index between baseline and 20 (ΔPI₂₀) or 40 s (ΔPI₄₀) after the beginning of EEOT were calculated using: ΔPI₂₀ (%) = [(PI at 20 s after EEOT beginning - PI_baseline)/PI_baseline] × 100, ΔPI₄₀ (%) = [(PI at 40 s after EEO beginning - PI_baseline)/PI_baseline] × 100).

RESULTS

Sixteen patients were responders, and 25 were non-responders. The area under the receiver operating characteristics curves generated for ΔPI₂₀ and ΔPI₄₀ to predict response to a fluid challenge were 0.561 (95% CI 0.374-0.749) and 0.688 (95% CI 0.523-0.852), respectively.

CONCLUSION

Changes in perfusion index during intraoperative EEOT in patients undergoing lung-protective ventilation (7 ml/kg) were unable to predict the response to fluid administration.

Changes in the Plethysmographic Perfusion Index During an End-Expiratory Occlusion Detect a Positive Passive Leg Raising Test

OBJECTIVES

The end-expiratory occlusion test for assessing preload responsiveness consists in interrupting mechanical ventilation for 15 seconds at end-expiration and measuring the cardiac index changes. The perfusion index is the ratio between the pulsatile and the nonpulsatile portions of the plethysmography signal and is, in part, determined by stroke volume. We tested whether the end-expiratory occlusion-induced changes in perfusion index could detect a positive passive leg raising test, suggesting preload responsiveness.

DESIGN

Observational study.

SETTING

Medical ICU.

PATIENTS

Thirty-one ventilated patients without atrial fibrillation.

INTERVENTIONS

We measured perfusion index (Radical-7 device; Masimo Corp., Irvine, CA) and cardiac index (PiCCO2; Pulsion Medical Systems, Feldkirchen, Germany) before and during a passive leg raising test and a 15-second end-expiratory occlusion.

MEASUREMENTS AND MAIN RESULTS

In 19 patients with a positive passive leg raising test (increase in cardiac index ≥ 10%), compared to the baseline value and expressed as a relative change, passive leg raising increased cardiac index and perfusion index by 17% ± 7% and 49% ± 23%, respectively, In these patients, end-expiratory occlusion increased cardiac index and perfusion index by 6% ± 2% and 11% ± 8%, respectively. In the 12 patients with a negative passive leg raising test, perfusion index did not significantly change during passive leg raising and end-expiratory occlusion. Relative changes in perfusion index and cardiac index observed during all interventions were significantly correlated (r = 0.83). An end-expiratory occlusion-induced relative increase in perfusion index greater than or equal to 2.5% ([perfusion index during end-expiratory occlusion-perfusion index at baseline]/perfusion index at baseline × 100) detected a positive passive leg raising test with an area under the receiver operating characteristic curve of 0.95 ± 0.03. This threshold is larger than the least significant change observed for perfusion index (1.62% ± 0.80%).

CONCLUSIONS

Perfusion index could be used as a reliable surrogate of cardiac index for performing the end-expiratory occlusion test. Confirming previous results, the relative changes in perfusion index also reliably detected a positive passive leg raising test.

Effects of Prone Positioning on Venous Return in Patients With Acute Respiratory Distress Syndrome

OBJECTIVES

To examine the effects of prone positioning on venous return and its determinants such as mean systemic pressure and venous return resistance in patients with acute respiratory distress syndrome.

DESIGN

Prospective monocentric study.

SETTINGS

A 25-bed medical ICU.

PATIENTS

About 22 patients with mild-to-severe acute respiratory distress syndrome in whom prone positioning was decided.

INTERVENTIONS

We obtained cardiac index, mean systemic pressure, and venous return resistance (the latter two estimated through the heart-lung interactions method) before and during prone positioning. Preload responsiveness was assessed at baseline using an end-expiratory occlusion test.

MEASUREMENTS AND MAIN RESULTS

Prone positioning significantly increased mean systemic pressure (from 24 mm Hg [19-34 mm Hg] to 35 mm Hg [32-46 mm Hg]). This was partly due to the trunk lowering performed before prone positioning. In seven patients, prone positioning increased cardiac index greater than or equal to 15%. All were preload responsive. In these patients, prone positioning increased mean systemic pressure by 82% (76-95%), central venous pressure by 33% (21-59%), (mean systemic pressure - central venous pressure) gradient by 144% (83-215)%, while it increased venous return resistance by 71% (60-154%). In 15 patients, prone positioning did not increase cardiac index greater than or equal to 15%. In these patients, prone positioning increased mean systemic pressure by 28% (18-56%) (p < 0.05 vs. patients with significant increase in cardiac index), central venous pressure by 21% (7-54%), (mean systemic pressure - central venous pressure) gradient by 28% (23-86%), and venous return resistance by 37% (17-77%). Eleven of these 15 patients were preload unresponsive.

CONCLUSIONS

Prone positioning increased mean systemic pressure in all patients. The resulting change in cardiac index depended on the extent of increase in (mean systemic pressure - central venous pressure) gradient, of preload responsiveness, and of the increase in venous return resistance. Cardiac index increased only in preload-responsive patients if the increase in venous return resistance was lower than the increase in the (mean systemic pressure -central venous pressure) gradient.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

COVID-19 and haemodynamic failure: a point of view on mechanisms and treatment

The SARS-CoV-2-related disease has an undoubted impact on the healthcare system. In the treatment of severe COVID-19 cases, the main focus is on respiratory failure. However, available data suggest an important contribution of haemodynamic impairment in the course of this disease. SARS-CoV-2 may affect the circulatory system in various ways that are universal for septic conditions. Nonetheless, unique features of this pathogen, e.g. direct insult leading to myocarditis and renin-angiotensin-aldosterone axis dysregulation, must be taken into account. Although current recommendations on COVID-19 resemble previous septic shock guidelines, special attention to haemodynamic monitoring and treatment is necessary. Regarding treatment, one must take into account the potential profound hypovolaemia of severe COVID-19 patients. Pharmacological cardiovascular support should follow existing guidelines and practice. Interesting concepts of decatecholaminisation and the effect of vasopressors on pulmonary circulation are also presented in this review on COVID-19-related haemodynamic failure.

Using Dynamic Variables to Guide Perioperative Fluid Management

Dynamic variables that quantify the variations in the arterial pressure and plethysmographic waveforms during mechanical ventilation reflect fluid responsiveness. These variables may be helpful in identifying occult hypovolemia and in preventing unnecessary fluid administration.

Prediction of fluid responsiveness in spontaneously breathing patients

In patients with acute circulatory failure, the primary goal of volume expansion is to increase cardiac output. However, this expected effect is inconstant, so that in many instances, fluid administration does not result in any haemodynamic benefit. In such cases, fluid could only exert some deleterious effects. It is now well demonstrated that excessive fluid administration is harmful, especially during acute respiratory distress syndrome and in sepsis or septic shock. This is the reason why some tests and indices have been developed in order to assess "fluid responsiveness" before deciding to perform volume expansion. While preload markers have been used for many years for this purpose, they have been repeatedly shown to be unreliable, which is mainly related to physiological issues. As alternatives, "dynamic" indices have been introduced. These indices are based upon the changes in cardiac output or stroke volume resulting from various changes in preload conditions, induced by heart-lung interactions, postural manoeuvres or by the infusion of small amounts of fluids. The haemodynamic effects and the reliability of these "dynamic" indices of fluid responsiveness are now well described. From their respective advantages and limitations, it is also possible to describe their clinical interest and the clinical setting in which they are applicable.

The end-expiratory occlusion test for detecting preload responsiveness: a systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis of studies assessing the end-expiratory occlusion test (EEXPO test)-induced changes in cardiac output (CO) measured by any haemodynamic monitoring device, as indicators of preload responsiveness.

METHODS

MEDLINE, EMBASE and Cochrane Database were screened for original articles. Bivariate random-effects meta-analysis determined the Area under the Summary Receiver Operating Characteristic (AUSROC) curve of EEXPO test-induced changes in CO to detect preload responsiveness, as well as pooled sensitivity and specificity and the best diagnostic threshold.

RESULTS

Thirteen studies (530 patients) were included. Nine studies were performed in the intensive care unit and four in the operating room. The pooled sensitivity and the pooled specificity for the EEXPO test-induced changes in CO were 0.85 [0.77-0.91] and 0.88 [0.83-0.91], respectively. The AUSROC curve was 0.91 [0.86-0.94] with the best threshold of CO increase at 5.1 ± 0.2%. The accuracy of the test was not different when changes in CO were monitored through pulse contour analysis compared to other methods (AUSROC: 0.93 [0.91-0.95] vs. 0.87 [0.82-0.96], respectively, p = 0.62). Also, it was not different in studies in which the tidal volume was ≤ 7 mL/kg compared to the remaining ones (AUSROC: 0.96 [0.92-0.97] vs. 0.89 [0.82-0.95] respectively, p = 0.44). Subgroup analyses identified one possible source of heterogeneity.

CONCLUSIONS

EEXPO test-induced changes in CO reliably detect preload responsiveness. The diagnostic performance is not influenced by the method used to track the EEXPO test-induced changes in CO. Trial registration The study protocol was prospectively registered on PROSPERO: CRD42019138265.

Management of perioperative volume therapy - monitoring and pitfalls

Over 300 million surgical procedures are performed every year worldwide. Anesthesiologists play an important role in the perioperative process by assessing the overall risk of surgery and aim to reduce the risk of complications. Perioperative hemodynamic and volume management can help to improve outcomes in perioperative patients. There has been ongoing discussion about goal-directed therapy. However, there is a consensus that fluid overload and severe fluid depletion in the perioperative period are harmful and can lead to adverse outcomes. This article provides an overview of how to evaluate the fluid responsiveness of patients, details which parameters could be used, and what limitations should be noted.

Interferon signature in immunosuppressed patients with lower respiratory tract infections: dosage on bronchoalveolar lavage

BACKGROUND

Interferon signature (IS) is the measure of transcripts belonging to pathways of interferon activation. Viral infections can interfere with the interferon pathway, in particular herpesvirus present in immunocompromised hosts. The aim of our study was to evaluate if herpesvirus infections in immunocompromised patients with lower respiratory tract infections (LRTI) could lead to IS alterations.

METHODS

We measured IS transcription of six genes on bronchoalveolar lavage of immunocompromised patients with LRTI (IFI27, IFI44, IFIT1, ISG15, RSAD2, SIGLEC1). Patients were divided in three groups based on Epstein-Barr virus (EBV) and other herpesviruses coinfections.

RESULTS

We included 56 patients, 10 without and 17 with only EBV reactivation (respectively N and E groups) and 29 with EBV and other herpesviruses (group C). IS was higher in group C (P=0.01) compared to other ones, but single gene expressions were different among groups: IFI27 was higher whereas IFIT1 and ISG15 were lower in group C (P<0.05).

CONCLUSIONS

The continuous stimulation of interferon cascade by herpesviruses enhances IS. The analysis of IS in immunocompromised population is possible by limiting the use of IFI27, IFIT1, ISG15 genes. Our preliminary results seem to indicate that IS is a useful biomarker of cellular response to herpesvirus infection in immunocompromised patients.