Monitoring dynamic arterial elastance as a means of decreasing the duration of norepinephrine treatment in vasoplegic syndrome following cardiac surgery: a prospective, randomized trial

Norepinephrine weaning guided by the Hypotension Prediction Index in vasoplegic shock after cardiac surgery: protocol for a single-centre, open-label randomised controlled trial - the NORAHPI study

INTRODUCTION

Norepinephrine (NE) is the first-line recommended vasopressor for restoring mean arterial pressure (MAP) in vasoplegic syndrome (vs) following cardiac surgery with cardiopulmonary bypass. However, solely focusing on target MAP values can lead to acute hypotension episodes during NE weaning. The Hypotension Prediction Index (HPI) is a machine learning algorithm embedded in the Acumen IQ device, capable of detecting hypotensive episodes before their clinical manifestation. This study evaluates the clinical benefits of an NE weaning strategy guided by the HPI.

MATERIAL AND ANALYSIS

The Norahpi trial is a prospective, open-label, single-centre study that randomises 142 patients. Inclusion criteria encompass adult patients scheduled for on-pump cardiac surgery with postsurgical NE administration for vs patient randomisation occurs once they achieve haemodynamic stability (MAP>65 mm Hg) for at least 4 hours on NE. Patients will be allocated to the intervention group (n=71) or the control group (n=71). In the intervention group, the NE weaning protocol is based on MAP>65 mmHg and HPI<80 and solely on MAP>65 mm Hg in the control group. Successful NE weaning is defined as achieving NE weaning within 72 hours of inclusion. An intention-to-treat analysis will be performed. The primary endpoint will compare the duration of NE administration between the two groups. The secondary endpoints will include the prevalence, frequency and time of arterial hypotensive events monitored by the Acumen IQ device. Additionally, we will assess cumulative diuresis, the total dose of NE, and the number of protocol weaning failures. We also aim to evaluate the occurrence of postoperative complications, the length of stay and all-cause mortality at 30 days.

ETHICS AND DISSEMINATION

Ethical approval has been secured from the Institutional Review Board (IRB) at the University Hospital of Amiens (IRB-ID:2023-A01058-37). The findings will be shared through peer-reviewed publications and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT05922982.

Prospective randomized double-blind study to evaluate the superiority of Vasopressin versus Norepinephrine in the management of the patient at renal risk undergoing cardiac surgery with cardiopulmonary bypass (NOVACC trial)

BACKGROUND

Cardiac surgery-associated acute kidney injury (CS-AKI) affects up to 30% of patients, increasing morbidity and healthcare costs. This condition results from complex factors like ischemia-reperfusion injury and renal hemodynamic changes, often exacerbated by surgical procedures. Norepinephrine, commonly used in cardiac surgeries, may heighten the risk of CS-AKI. In contrast, vasopressin, a noncatecholaminergic agent, shows potential in preserving renal function by favorably affecting renal hemodynamic. Preliminary findings, suggest vasopressin could reduce the incidence of CS-AKI compared to norepinephrine. Additionally, vasopressin is linked to a lower incidence of postoperative atrial fibrillation, another factor contributing to longer hospital stays and higher costs. This study hypothesizes that vasopressin could effectively reduce CS-AKI occurrence and severity by optimizing renal perfusion during cardiac surgeries.

STUDY DESIGN

The NOVACC trial (NCT05568160) is a multicenter, randomized, double blinded superiority-controlled trial testing the superiority of vasopressin over norepinephrine in patients scheduled for cardiac surgery with cardiopulmonary bypass (CPB). The primary composite end point is the occurrence of acute kidney injury and death. The secondary end points are neurological, cardiologic, digestive, and vasopressor related complications at day 7, day 30, day 90, hospital and intensive care unit lengths of stay, medico-economic costs at day 90.

CONCLUSION

The NOVACC trial will assess the effectiveness of vasopressin in cardiac surgery with CPB in reducing acute kidney injury, mortality, and medical costs.

CLINICAL TRIAL REGISTRATION

NCT05568160.

Maintenance of beta-blockers and cardiac surgery-related outcomes: a prospective propensity-matched multicentre analysis

BACKGROUND

We investigated the effects of maintaining beta-blockers on the day of surgery on the incidence of atrial fibrillation and postoperative acute kidney injury (AKI) in patients undergoing cardiac surgery.

METHODS

We conducted a multicentre prospective observational study with propensity matching on patients treated with beta-blockers. We collected their baseline patient characteristics, comorbidities, and operative and postoperative outcomes. The endpoints were postoperative atrial fibrillation and AKI after cardiac surgery.

RESULTS

Of the 1789 included patients, propensity matching led to 583 patients in each group. Maintenance of beta-blockers was not associated with a reduced risk of atrial fibrillation (odds ratio: 0.86 [95% confidence interval 0.66-1.14], P=0.335; 141 patients [24.2%] vs 126 patients [21.6%]). Sensitivity analysis did not demonstrate association between beta-blocker maintenance and atrial fibrillation after cardiac surgery (odds ratio: 0.93 [95% confidence interval: 0.72-1.22], P=0.625). Maintenance of beta-blockers was associated with a higher rate of norepinephrine use (415 [71.2%] vs 465 [79.8%], P=0.0001) and postoperative AKI (124 [21.3%] vs 159 [27.3%], P=0.0127). No statistically significant difference was observed in ICU length of stay.

CONCLUSIONS

Maintenance of beta-blockers on the day of surgery was not associated with a reduced incidence of postoperative atrial fibrillation. However, maintenance of beta-blockers was associated with increased usage of vasopressors, potentially contributing to adverse postoperative renal events.

CLINICAL TRIAL REGISTRATION

NCT04769752.

Dynamic arterial elastance as a predictor of arterial pressure response to norepinephrine weaning in mechanically ventilated patients with vasoplegic syndrome-a systematic review and meta-analysis

Introduction

During the de-escalation phase of circulatory shock, norepinephrine weaning may induce diverse arterial pressure responses in patients with different vasomotor tones. Dynamic arterial elastance (Eadyn) has been extensively studied to predict the arterial pressure response to interventions. We conducted this meta-analysis to systematically assess the predictive performance of Eadyn for the mean arterial pressure (MAP) response to norepinephrine weaning in mechanically ventilated patients with vasoplegic syndrome.

Materials and methods

A systematic literature search was conducted on May 29, 2023 (updated on January 21, 2024), to identify relevant studies from electronic databases. The area under the hierarchical summary receiver operating characteristic curve (AUHSROC) was estimated as the primary measure of diagnostic accuracy because of the varied thresholds reported. Additionally, we observed the distribution of the cutoff values of Eadyn, while computing the optimal value and its corresponding 95% confidential interval (CI).

Results

A total of 5 prospective studies met eligibility, comprising 183 participants, of whom 67 (37%) were MAP responders. Eadyn possessed an excellent ability to predict the MAP response to norepinephrine weaning in patients with vasoplegic syndrome, with an AUHSROC of 0.93 (95% CI: 0.91-0.95), a pooled sensitivity of 0.94 (95% CI: 0.85-0.98), a pooled specificity of 0.73 (95% CI: 0.65-0.81), and a pooled diagnostic odds ratio of 32.4 (95% CI: 11.7-89.9). The cutoff values of Eadyn presented a nearly conically symmetrical distribution; the mean and median cutoff values were 0.89 (95% CI: 0.80-0.98) and 0.90 (95% CI: not estimable), respectively.

Conclusions

This meta-analysis with limited evidences demonstrates that Eadyn may be a reliable predictor of the MAP response to norepinephrine weaning in mechanically ventilated patients with vasoplegic syndrome.

Systematic Review Registration

PROSPERO CRD42023430362.

Advanced Variables to Optimize Hemodynamic Monitoring

Measuring hemodynamic parameters has become safer and more precise than in the past. Accurately monitoring and evaluating the effectiveness of fluid, inotrope, and vasoactive medication administration can improve patient outcomes. Arbitrary fluid administration without stroke volume measurement can be detrimental to patient outcomes. Early detection and prompt treatment of shock states is essential to combat deleterious effects on critically ill patients. In addition to measuring traditional hemodynamic variables, the use of advanced variables such as hypotension prediction index, dynamic arterial elastance, and systolic slope can improve the precision of treat ment for critically ill patients. Using predictive analytics can help the bedside critical care nurse provide patient care that is proactive rather than reactive.

UNVEILING THE SIGNIFICANCE OF DYNAMIC ARTERIAL ELASTANCE: AN INSIGHTFUL APPROACH TO ASSESSING ARTERIAL LOAD IN AN ENDOTOXIN SHOCK MODEL

ABSTRACT

Background: The aim of this study was to investigate the relationship between dynamic arterial elastance (EaDyn) and the pulsatile and steady components of arterial load in an endotoxin shock model using a two-element Windkessel model and to describe the behavior of EaDyn in this model. Methods : Ten female Yorkshire pigs were administered lipopolysaccharide intravenously to induce endotoxin shock, while three female pigs served as the control group. Measurements of EaDyn (ratio between pulse pressure variation and stroke volume variation), effective arterial elastance, arterial compliance (Cart), and systemic vascular resistance were taken every 30 min in the endotoxin group until shock was induced. In the control group, these variables were measured every 30 min for 3 h. Subsequently, a fluid load was administered to both groups, and measurements were repeated every 30 min. After 1 hour of shock induction, the endotoxin group was divided into two subgroups: one receiving norepinephrine (END-NE) and the other not receiving it (END-F). Results: EaDyn showed an association with Cart, while pulse pressure variation was connected to both pulsatile and steady components, and stroke volume variation was solely associated with steady components. In addition, EaDyn exhibited higher values in the END groups than in the control group when shock was achieved. Furthermore, after the administration of norepinephrine, EaDyn displayed higher values in END-F than in END-NE. Conclusions: The EaDyn variable helps identify changes in the pulsatile component of arterial load, providing valuable guidance for management strategies aimed at improving cardiac performance.

Pressure- vs. volume-controlled ventilation and their respective impact on dynamic parameters of fluid responsiveness: a cross-over animal study

BACKGROUND AND GOAL OF STUDY

Pulse pressure variation (PPV) and stroke volume variation (SVV), which are based on the forces caused by controlled mechanical ventilation, are commonly used to predict fluid responsiveness. When PPV and SVV were introduced into clinical practice, volume-controlled ventilation (VCV) with tidal volumes (VT) ≥ 10 ml kg- 1 was most commonly used. Nowadays, lower VT and the use of pressure-controlled ventilation (PCV) has widely become the preferred type of ventilation. Due to their specific flow characteristics, VCV and PCV result in different airway pressures at comparable tidal volumes. We hypothesised that higher inspiratory pressures would result in higher PPVs and aimed to determine the impact of VCV and PCV on PPV and SVV.

METHODS

In this self-controlled animal study, sixteen anaesthetised, paralysed, and mechanically ventilated (goal: VT 8 ml kg- 1) pigs were instrumented with catheters for continuous arterial blood pressure measurement and transpulmonary thermodilution. At four different intravascular fluid states (IVFS; baseline, hypovolaemia, resuscitation I and II), ventilatory and hemodynamic data including PPV and SVV were assessed during VCV and PCV. Statistical analysis was performed using U-test and RM ANOVA on ranks as well as descriptive LDA and GEE analysis.

RESULTS

Complete data sets were available of eight pigs. VT and respiratory rates were similar in both forms. Heart rate, central venous, systolic, diastolic, and mean arterial pressures were not different between VCV and PCV at any IVFS. Peak inspiratory pressure was significantly higher in VCV, while plateau, airway and transpulmonary driving pressures were significantly higher in PCV. However, these higher pressures did not result in different PPVs nor SVVs at any IVFS.

CONCLUSION

VCV and PCV at similar tidal volumes and respiratory rates produced PPVs and SVVs without clinically meaningful differences in this experimental setting. Further research is needed to transfer these results to humans.

Effect of norepinephrine on the vascular waterfall and tissue perfusion in vasoplegic hypotensive patients: a prospective, observational, applied physiology study in cardiac surgery

BACKGROUND

Norepinephrine is a commonly used drug for treating vasoplegic acute circulatory failure in ICU. The prediction of norepinephrine macro- and micro-circulatory response is complicated by its uneven receptors' distribution between the arterial and the venous structures, and by the presence of a physiological vascular waterfall (VW) that disconnects the arterial and the venous circulation in two pressure systems. The objectives of this study were to describe the VW in patients with arterial hypotension due to vasodilatory circulatory shock, and its behavior according to its response to norepinephrine infusion.

METHODS

A prospective, observational, bi-centric study has included adult patients, for whom the physician decided to initiate norepinephrine during the six first hours following admission to the ICU after cardiac surgery, and unresponsive to a fluid challenge. The mean systemic pressure (MSP) and the critical closing pressure (CCP) were measured at inclusion and after norepinephrine infusion.

RESULTS

Thirty patients were included. Norepinephrine increased arterial pressure and total peripheral resistances in all cohort. The cohort was dichotomized as VW responders (patients with a change of VW over the least significant change (≥ 93% increase in VW)), and as VW non-responders. In 19 (63%) of the 30 patients, VW increased from 3.47 [- 14.43;7.71] mmHg to 43.6 [25.8;48.1] mmHg, p < 0.001) with norepinephrine infusion, being classified as VW responders. The VW responders improved cardiac index (from 1.8 (0.6) L min-1 m-2 to 2.2 (0.5) L min-1 m-2, p = 0.002), capillary refill time (from to 4.2 (1.1) s to 3.1 (1) s, p = 0.006), and pCO2 gap (from 9 [7;10] mmHg to 6 [4;8] mmHg, p = 0.04). No baseline parameters were able to predict the VW response to norepinephrine. In comparison, VW non-responders did not significantly change the VW (from 5 [-5;16] mmHg to -2 [-12;15] mmHg, p = 0.17), cardiac index (from 1.6 (0.3) L min-1 m-2 to 1.8 (0.4) L min-1 m-2, p = 0.09) and capillary refill time (from 4.1 (1) s to 3.7 (1.4), p = 0.44).

CONCLUSIONS

In post-cardiac surgery patients with vasoplegic arterial hypotension, the vascular waterfall is low. Norepinephrine did not systematically restore the vascular waterfall. Increase of the vascular waterfall was associated with an improvement of laboratory and clinical parameters of tissue perfusion.

A norepinephrine weaning strategy using dynamic arterial elastance is associated with reduction of acute kidney injury in patients with vasoplegia after cardiac surgery: A post-hoc analysis of the randomized SNEAD study

STUDY OBJECTIVE

To evaluate the impact of a dynamic arterial elastance guided norepinephrine weaning strategy on the occurrence of acute kidney injury (AKI) in patients with vasoplegia after cardiac surgery.

DESIGN

A post-hoc analysis of a monocentric randomized controlled trial.

SETTING

A tertiary care hospital in France.

PARTICIPANTS

Vasoplegic cardiac surgical patients treated with norepinephrine.

INTERVENTION

Patients were randomized to an algorithm-based norepinephrine weaning intervention (dynamic arterial elastance) group or a control group.

MEASUREMENTS

The primary endpoint was the number of patients with AKI defined according to Kidney Disease Improving Global Outcomes (KDIGO) criteria. The secondary endpoint were major adverse cardiac post-operative events (new onset of atrial fibrillation or flutter, low cardiac output syndrome, and in-hospital death). End points were evaluated during the first seven post-operative days.

RESULTS

118 patients were analyzed. In the overall study population, the mean age was 70 (62-76) years, 65% were male and the median EuroSCORE was 7 (5-10). Overall, 46 (39%) patients developed AKI (30 KDIGO 1, 8 KDIGO 2, 8 KDIGO 3), and 6 patients required renal replacement therapy. The incidence of AKI was significantly lower in the intervention group than in the control group (16 patients (27%) vs 30 patients (51%), p = 0.12). Higher dose and longer duration of norepinephrine were associated with AKI severity.

CONCLUSION

Decreasing norepinephrine exposure by using a dynamic arterial elastance guided norepinephrine weaning strategy was associated with a reduced incidence of acute kidney injury in patients with vasoplegia after cardiac surgery. Further prospective multicentric studies are needed to confirm these results.

Epidemiology, risk factors and outcomes of norepinephrine use in cardiac surgery with cardiopulmonary bypass: a multicentric prospective study

BACKGROUND

The present study was designed to describe the prevalence of norepinephrine use, the factors associated with its use, and the incidence of postoperative complications according to norepinephrine use, in patients undergoing cardiac surgery with cardiopulmonary bypass.

METHOD

We performed a prospective, multicenter, observational study in 4 University-affiliated medico-surgical cardiovascular units. We analyzed all patients treated with cardiac surgery after excluding pre-ECMO surgery, LVAD implantation, heart transplantation and intra-operative hemorrhage.

RESULTS

Of 9316 patients screened during the study period, 2862 were included and 2510 were analyzed. Among them, 1549 (61%) were treated with norepinephrine with a median maximal dose of 0.11 [0.06-0.2] μg.kg^-1.min^-1 and a median duration of 10 h [2-24]. Norepinephrine was most often started in the operating room before cardiopulmonary bypass. The multiple regression logistic analysis identified several modifiable (haematocrit, maintenance of beta-blocker, cardiopulmonary bypass time, glucose-insulin-potassium, Custodiol cardioplegia, Delnido cardioplegia, and fibrinogen transfusion) and non-modifiable factors (age, ASA score, chronic high blood pressure, coronary disease, dyslipidemia, right ventricular dysfunction, left ventricular dysfunction, active endocarditis, and valvular aortic surgery) associated with norepinephrine use. Mortality, morbidity (neurological and renal complications, death) and length of stay in the ICU were higher in patients treated with norepinephrine.

CONCLUSION

Norepinephrine is often used in cardiac surgical patients but for <24 h with a low dose. Many preoperative and surgical factors are associated with norepinephrine use. Patients supported by norepinephrine have a higher incidence of major postoperative events.

Dynamic Arterial Elastance to Predict Mean Arterial Pressure Decrease after Reduction of Vasopressor in Septic Shock Patients

After fluid status optimization, norepinephrine infusion represents the cornerstone of septic shock treatment. De-escalation of vasopressors should be considered with caution, as hypotension increases the risk of mortality. In this prospective observational study including 42 patients, we assess the role of dynamic elastance (EaDyn), i.e., the ratio between pulse pressure variation and stroke volume variation, which can be measured noninvasively by the MostCare monitoring system, to predict a mean arterial pressure (MAP) drop > 10% 30 min after norepinephrine reduction. Patients were divided into responders (MAP falling > 10%) and non-responders (MAP falling < 10%). The receiver-operating-characteristic curve identified an area under the curve of the EaDyn value to predict a MAP decrease > 10% of 0.84. An EaDyn cut-off of 0.84 predicted a MAP drop > 10% with a sensitivity of 0.71 and a specificity of 0.89. In a multivariate logistic regression, EaDyn was significantly and independently associated with MAP decrease (OR 0.001, 95% confidence interval 0.00001−0.081, p < 0.001). The nomogram model for the probability of MAP decrease > 10% showed a C-index of 0.90. In conclusion, in a septic shock cohort, EaDyn correlates well with the risk of decrease of MAP > 10% after norepinephrine reduction.

Effective hemodynamic monitoring

Hemodynamic monitoring is the centerpiece of patient monitoring in acute care settings. Its effectiveness in terms of improved patient outcomes is difficult to quantify. This review focused on effectiveness of monitoring-linked resuscitation strategies from: (1) process-specific monitoring that allows for non-specific prevention of new onset cardiovascular insufficiency (CVI) in perioperative care. Such goal-directed therapy is associated with decreased perioperative complications and length of stay in high-risk surgery patients. (2) Patient-specific personalized resuscitation approaches for CVI. These approaches including dynamic measures to define volume responsiveness and vasomotor tone, limiting less fluid administration and vasopressor duration, reduced length of care. (3) Hemodynamic monitoring to predict future CVI using machine learning approaches. These approaches presently focus on predicting hypotension. Future clinical trials assessing hemodynamic monitoring need to focus on process-specific monitoring based on modifying therapeutic interventions known to improve patient-centered outcomes.

Association between acute kidney injury and norepinephrine use following cardiac surgery: a retrospective propensity score-weighted analysis

Background

Excess exposure to norepinephrine can compromise microcirculation and organ function. We aimed to assess the association between norepinephrine exposure and acute kidney injury (AKI) and intensive care unit (ICU) mortality after cardiac surgery.

Methods

This retrospective observational study included adult patients who underwent cardiac surgery under cardiopulmonary bypass from January 1, 2008, to December 31, 2017, at the Amiens University Hospital in France. The primary exposure variable was postoperative norepinephrine during the ICU stay and the primary endpoint was the presence of AKI. The secondary endpoint was in-ICU mortality. As the cohort was nonrandom, inverse probability weighting (IPW) derived from propensity scores was used to reduce imbalances in the pre- and intra-operative characteristics.

Results

Among a population of 5053 patients, 1605 (32%) were exposed to norepinephrine following cardiac surgery. Before weighting, the prevalence of AKI was 25% and ICU mortality 10% for patients exposed to norepinephrine. Exposure to norepinephrine was estimated to be significantly associated with AKI by a factor of 1.95 (95% confidence interval, 1.63–2.34%; P < 0.001) in the IPW cohort and with in-ICU mortality by a factor of 1.54 (95% confidence interval, 1.19–1.99%; P < 0.001).

Conclusion

Norepinephrine was associated with AKI and in-ICU mortality following cardiac surgery. While these results discourage norepinephrine use for vasoplegic syndrome in cardiac surgery, prospective investigations are needed to substantiate findings and to suggest alternative strategies for organ protection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01037-1.

Arterial Hypotension Following Norepinephrine Decrease in Septic Shock Patients Is Not Related to Preload Dependence: A Prospective, Observational Cohort Study

Background

The optimal management of hypotensive patients during norepinephrine weaning is unclear. The primary study aim was to assess the ability of preload dependence to predict hypotension following norepinephrine weaning. The secondary aims were to describe the effect of norepinephrine weaning on preload dependence, and the cardiovascular effects of fluid expansion in hypotensive patients following norepinephrine weaning.

Materials and Methods

This was a prospective observational monocentric study. We included PiCCO®-monitored patients with norepinephrine-treated septic shock, for whom the physician decided to decrease the norepinephrine dosage during the de-escalation phase. Three consecutive steps were evaluated with hemodynamic measurements: baseline, after norepinephrine decrease, and after 500 mL fluid expansion.

Results

Forty-five patients were included. Preload dependence assessed by stroke volume changes following passive leg raising was not predictive of pressure response to norepinephrine weaning [AUC of 0.42 (95%CI: 0.25–0.59, p = 0.395)]. After fluid expansion, there was no difference in the prior preload dependence between pressure-responders and non-pressure-responders (14 vs. 13%, p = 1). The pressure response to norepinephrine decrease was not associated with pressure response after fluid expansion (40 vs. 23%, p = 0.211).

Conclusion

Hypotension following norepinephrine decrease was not predicted by preload dependence, and there was no association between arterial hypotension after norepinephrine decrease and fluid response.

Ventriculo-Arterial Coupling Is Associated With Oxygen Consumption and Tissue Perfusion in Acute Circulatory Failure

Introduction

The determination of ventriculo-arterial coupling is gaining an increasing role in cardiovascular and sport medicine. However, its relevance in critically ill patients is still under investigation. In this study we measured the association between ventriculo-arterial coupling and oxygen consumption (VO2) response after hemodynamic interventions in cardiac surgery patients with acute circulatory instability.

Material and Methods

Sixty-one cardio-thoracic ICU patients (67 ± 12 years, 80% men) who received hemodynamic therapeutic interventions (fluid challenge or norepinephrine infusion) were included. Arterial pressure, cardiac output, heart rate, arterial (EA), and ventricular elastances (EV), total indexed peripheral resistances were assessed before and after hemodynamic interventions. VO2 responsiveness was defined as VO2 increase &gt;15% following the hemodynamic intervention. Ventriculo-arterial coupling was assessed measuring the EA/EV ratio by echocardiography. The left ventricle stroke work to pressure volume area ratio (SW/PVA) was also calculated.

Results

In the overall cohort, 24 patients (39%) were VO2 responders, and 48 patients had high ventriculo-arterial (EA/EV) coupling ratio with a median value of 1.9 (1.6–2.4). Most of those patients were classified as VO2 responders (28 of 31 patients, p = 0.031). Changes in VO2 were correlated with those of indexed total peripheral resistances, EA, EA/EV and cardiac output. EA/EV ratio predicted VO2 increase with an AUC of 0.76 [95% CI: 0.62–0.87]; p = 0.001. In principal component analyses, EA/EV and SW/PVA ratios were independently associated (p &lt; 0.05) with VO2 response following interventions.

Conclusions

VO2 responders were characterized by baseline high ventriculo-arterial coupling ratio due to high EA and low EV. Baseline EA/EV and SW/PVA ratios were associated with VO2 changes independently of the hemodynamic intervention used. These results underline the pathophysiological significance of measuring ventriculo-arterial coupling in patients with hemodynamic instability, as a potential therapeutic target.

Optimizing left ventricular-arterial coupling during the initial resuscitation in septic shock – a pilot prospective randomized study

Background

Left ventricular-arterial coupling (VAC), defined as the ratio of effective arterial elastance (Ea) to left ventricular end-systolic elastance (Ees), has been extensively described as a key determinant of cardiovascular work efficacy. Previous studies indicated that left ventricular-arterial uncoupling was associated with worse tissue perfusion and increased mortality in shock patients. Therefore, this study aims to investigate whether a resuscitation algorithm based on optimizing left VAC during the initial resuscitation can improve prognosis in patients with septic shock.

Methods

This pilot study was conducted in an intensive care unit (ICU) of a tertiary teaching hospital in China. A total of 83 septic shock patients with left ventricular-arterial uncoupling (i.e., the Ea/Ees ratio ≥ 1.36) were randomly assigned to receive usual care (usual care group, n = 42) or an algorithm-based resuscitation that attempt to reduce the Ea/Ees ratio to 1 within the first 6 h after randomization (VAC-optimized group, n = 41). The left VAC was evaluated by transthoracic echocardiography every 2 h during the study period. The primary endpoint was 28-days mortality. The secondary endpoints included lactate clearance rate, length of ICU stay, and duration of invasive mechanical ventilation (IMV).

Results

Eighty-two patients (98.8%) completed the study and were included in the final analysis. The Ea/Ees ratio was reduced in both groups, and the decrease in Ea/Ees ratio in the VAC-optimized group was significantly greater than that in the usual care group [median (interquartile range), 0.39 (0.26, 0.45) vs. 0.1 (0.06, 0.22); P < 0.001]. Compared with the usual care group, the VAC-optimized group likely exhibited the potential to reduce the 28-days mortality (33% vs. 50%; log-rank hazard ratio = 0.526, 95% confidence interval: 0.268 to 1.033). Moreover, the VAC-optimized group had a higher lactate clearance rate than the usual care group [27.7 (11.9, 45.7) % vs. 18.3 (− 5.7, 32.1) %; P = 0.038]. No significant difference was observed in terms of the length of ICU stay or duration of IMV.

Conclusions

During the initial resuscitation of septic shock, optimizing left ventricular-arterial coupling was associated with improved lactate clearance, while likely having a beneficial effect on prognosis.

Trial registration

Chinese Clinical Trial Registry, ChiCTR1900024031. Registered 23 June 2019 - Retrospectively registered.

Inotropes and vasopressors are associated with increased short-term mortality but not long-term survival in critically ill patients

OBJECTIVE

Limited information is currently available on the impact of vasoactive medications in intensive care (ICU) and long-term outcomes. The main objective of our study was to describe the association between the use of inotropes and/or vasopressors and ICU mortality. Secondary objectives were to evaluate the association between the use of vasoactive drugs and in-hospital as well as 1-year all-cause mortality in ICU survivors.

METHODS

FROG-ICU was a prospective, observational, multi-centre cohort designed to investigate long-term mortality of critically ill adult patients. Cox proportional hazards models were used to evaluate the association between the use of inotropes and/or vasopressors and ICU mortality, as well as in-hospital and 1-year all-cause mortality in a propensity-score matched cohort.

RESULTS

The study included 2087 patients, 939 of whom received inotropes and/or vasopressors during the initial ICU stay. Patients treated with vasoactive medications were older and had a more severe clinical presentation. In a propensity score-matched cohort of 1201 patients, ICU mortality was higher in patients who received vasoactive medications (HR of 1.40 [1.10 - 1.78], p = 0.007). One thousand six hundred thirty-five patients survived the index ICU hospitalisation. There was no significant difference according to the use of inotropes and/or vasopressors in the propensity-score matched cohort on in-hospital mortality (HR of 0.94 [0.60 - 1.49], p = 0.808) as well as one-year all-cause mortality (HR 0.94 [0.71 - 1.24], p = 0.643).

CONCLUSION

Inotropic and/or vasopressor therapy is a strong predictor of in-ICU death. However, the use of inotropes and/or vasopressors during ICU admission was not associated with a worse prognosis after ICU discharge.

Portal Vein Pulsatility as a Dynamic Marker of Venous Congestion Following Cardiac Surgery: An Interventional Study Using Positive End-Expiratory Pressure

We aimed to assess variations in the portal vein pulsatility index (PI) during mechanical ventilation following cardiac surgery. Method. After ethical approval, we conducted a prospective monocentric study at Amiens University Hospital. Patients under mechanical ventilation following cardiac surgery were enrolled. Doppler evaluation of the portal vein (PV) was performed by transthoracic echography. The maximum velocity (VMAX) and minimum velocity (VMIN) of the PV were measured in pulsed Doppler mode. The PI was calculated using the following formula (VMAX − VMIN)/(VMax). A positive end-expiratory pressure (PEEP) incremental trial was performed from 0 to 15 cmH₂O, with increments of 5 cmH₂O. The PI (%) was assessed at baseline and PEEP 5, 10, and 15 cmH₂O. Echocardiographic and hemodynamic parameters were recorded. Results. In total, 144 patients were screened from February 2018 to March 2019 and 29 were enrolled. Central venous pressure significantly increased for each PEEP increment. Stroke volumes were significantly lower after PEEP incrementation, with 52 mL (50–55) at PEEP 0 cmH₂O and 30 mL (25–45) at PEEP 15 cmH₂O, (p < 0.0001). The PI significantly increased with PEEP incrementation, from 9% (5–15) at PEEP 0 cmH₂O to 15% (5–22) at PEEP 5 cmH₂O, 34% (23–44) at PEEP 10 cmH₂O, and 45% (25–49) at PEEP 15 cmH₂O (p < 0.001). Conclusion. In the present study, PI appears to be a dynamic marker of the interaction between mechanical ventilation and right heart pressure after cardiac surgery. The PI could be a useful noninvasive tool to monitor venous congestion associated with mechanical ventilation.

Vasopressor-Sparing Strategies in Patients with Shock: A Scoping-Review and an Evidence-Based Strategy Proposition

Despite the abundant literature on vasopressor therapy, few studies have focused on vasopressor-sparing strategies in patients with shock. We performed a scoping-review of the published studies evaluating vasopressor-sparing strategies by analyzing the results from randomized controlled trials conducted in patients with shock, with a focus on vasopressor doses and/or duration reduction. We analyzed 143 studies, mainly performed in septic shock. Our analysis demonstrated that several pharmacological and non-pharmacological strategies are associated with a decrease in the duration of vasopressor therapy. These strategies are as follows: implementing a weaning strategy, vasopressin use, systemic glucocorticoid administration, beta-blockers, and normothermia. On the contrary, early goal directed therapies, including fluid therapy, oral vasopressors, vitamin C, and renal replacement therapy, are not associated with an increase in vasopressor-free days. Based on these results, we proposed an evidence-based vasopressor management strategy.

Effect of the oXiris membrane on microcirculation after cardiac surgery under cardiopulmonary bypass: study protocol for a randomised controlled trial (OXICARD Study)

INTRODUCTION

Cytokine storm and endotoxin release during cardiac surgery with cardiopulmonary bypass (CPB) have been related to vasoplegic shock and organ dysfunction. We hypothesised that early (during CPB) cytokine adsorption with oXiris membrane for patients at high risk of inflammatory syndrome following cardiac surgery may improve microcirculation, endothelial function and outcomes.

METHODS AND ANALYSIS

The Oxicard trial is a prospective, monocentric trial, randomising 70 patients scheduled for cardiac surgery. The inclusion criterion is patients aged more than 18 years old undergoing elective cardiac surgery under CPB with an expected CPB time >90 min (double valve replacement or valve replacement plus coronary arterial bypass graft). Patients will be allocated to the intervention group (n=35) or the control group (n=35). In the intervention group, oXiris membrane will be used on the Prismaflex device (Baxter) at blood pump flow of 450 mL/min during cardiac surgery under CPB. In the control group, cardiac surgery under CPB will be conducted as usual without oXiris membrane. An intention-to-treat analysis will be performed. The primary endpoint will be the microcirculatory flow index measured by sublingual microcirculation device at day 1 following cardiac surgery. The secondary endpoints will be other microcirculation variables at CPB end, 6 hours after CPB, at day 1 and at day 2. We also aim to evaluate the occurrence of major cardiovascular and cerebral events (eg, myocardial infarction, stroke, ischaemic mesenteric, resuscitated cardiac arrest, acute kidney injury) within the first 30 days. Cumulative catecholamine use, intensive care unit length of stay, endothelium glycocalyx shedding parameters (syndecan-1, heparan-sulfate and hyaluronic acid), inflammatory cytokines (tumour necrosis factor (TNF) alpha, interleukin 1 (IL1) beta, IL 10, IL 6, lipopolysaccharide, endothelin) and endothelial permeability biomarkers (angiopoietin 1, angiopoietin 2, Tie2 soluble receptor and Vascular Endothelial Growth Factor (VEGF) will also be evaluated.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Institutional Review Board of the University Hospital of Amiens (registration number ID RDB: 2019-A02437-50 in February 2020). Results of the study will be disseminated via peer-reviewed publications and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT04201119.

Dynamic Arterial Elastance Is Associated With the Vascular Waterfall in Patients Treated With Norepinephrine: An Observational Study

Introduction: It has been suggested that dynamic arterial elastance (Ea_dyn) can predict decreases in arterial pressure in response to changing norepinephrine levels. The objective of this study was to determine whether Ea_dyn is correlated with determinants of the vascular waterfall [critical closing pressure (CCP) and systemic arterial resistance (SARi)] in patients treated with norepinephrine.

Materials and Methods: Patients treated with norepinephrine for vasoplegia following cardiac surgery were studied. Vascular and flow parameters were recorded immediately before the norepinephrine infusion and then again once hemodynamic parameters had been stable for 15 min. The primary outcomes were Ea_dyn and its associations with CCP and SARi. The secondary outcomes were the associations between Ea_dyn and vascular/flow parameters.

Results: At baseline, all patients were hypotensive with Ea_dyn of 0.93 [0.47;1.27]. Norepinephrine increased the arterial blood pressure, cardiac index, CCP, total peripheral resistance (TPRi), arterial elastance, and ventricular elastance and decreased Ea_dyn [0.40 (0.30;0.60)] and SARi. Ea_dyn was significantly associated with arterial compliance (C_A), CCP, and TPRi (p < 0.05).

Conclusion: In patients with vasoplegic syndrome, Ea_dyn was correlated with determinants of the vascular waterfall. Ea_dyn is an easy-to-read functional index of arterial load that can be used to assess the patient’s macro/microcirculatory status.

Clinical Trial Registration:ClinicalTrials.gov #NCT03478709.

Dynamic arterial elastance measured with pressure recording analytical method, and mean arterial pressure responsiveness in hypotensive preload dependent patients undergoing cardiac surgery: A prospective cohort study

BACKGROUND

Organ perfusion is a factor of cardiac output and perfusion pressure. Recent evidence shows that dynamic arterial elastance is a reliable index of the interaction between the left ventricle and the arterial system and, in turn, of left ventricular mechanical efficiency. A practical approach to the assessment of dynamic arterial elastance at the bedside is the ratio between pulse pressure variation and stroke volume variation, which might predict the effect of a fluid challenge on the arterial pressure in patients undergoing cardiac surgery.

OBJECTIVE

To evaluate the ability of dynamic arterial elastance, measured by the pressure recording analytical method (PRAM), to predict the response of mean arterial pressure (MAP) to a fluid challenge.

DESIGN

Prospective observational study.

SETTING

Cardiac surgery patients in a university hospital.

PATIENTS

Preload-dependent (pulse pressure variation ≥13%), hypotensive (MAP ≤65 mmHg) patients, without right ventricular dysfunction, at the end of cardiac surgery.

INTERVENTIONS

A 250 ml fluid challenge infused over 3 min.

MAIN OUTCOME MEASURES

A receiver-operating characteristic curve was generated to test the ability of the baseline (before fluid challenge) dynamic arterial elastance (primary endpoint) and all other haemodynamic variables (secondary endpoint) to predict MAP responsiveness (≥10% increase in MAP) after a fluid challenge.

RESULTS

Of 270 patients undergoing cardiac surgery, 97 (35.9%) were preload-dependent, hypotensive and received a fluid challenge. Of these 97 patients, 50 (51%) were MAP responders (≥10% increase in MAP) and 47 (48%) were MAP nonresponders (<10% increase in MAP). Baseline dynamic arterial elastance (mean ± SD) had an area under the curve of 0.64 ± 0.06 [95% confidence interval (CI), 0.53 to 0.73; P = 0.017]. A dynamic arterial elastance at least 1.07 with a grey zone ranging between 0.9 and 1.5 had 86% sensitivity (95% CI, 73 to 94) and 45% specificity (95% CI, 30 to 60) in predicting MAP increase.

CONCLUSION

In a hypotensive preload-dependent cardiac surgery cohort without right ventricular dysfunction, dynamic arterial elastance measured by PRAM can predict pressure response for values greater than 1.5 or less than 0.9.

Echocardiographic measure of dynamic arterial elastance predict pressure response during norepinephrine weaning: an observational study

The purpose of this study was to determine whether dynamic elastance E_Adyn derived from echocardiographic measurements of stroke volume variations can predict the success of a one-step decrease of norepinephrine dose. In this prospective single-center study, 39 patients with vasoplegic syndrome treated with norepinephrine and for whom the attending physician had decided to decrease norepinephrine dose and monitored by thermodilution were analyzed. E_Adyn is the ratio of pulse pressure variation to stroke volume variation and was calculated from echocardiography stroke volume variations and from transpulmonary thermodilution. Pulse pressure variation was obtained from invasive arterial monitoring. Responders were defined by a decrease in mean arterial pressure (MAP) > 10% following norepinephrine decrease. The median decrease in norepinephrine was of 0.04 [0.03-0.05] µg kg^-1 min^-1. Twelve patients (31%) were classified as pressure responders with a median decrease in MAP of 13% [12-15%]. E_Adyn was lower in pressure responders (0.40 [0.24-0.57] vs 0.95 [0.77-1.09], p < 0.01). E_Adyn was able to discriminate between pressure responders and non-responders with an area under the curve of 0.86 (CI_95% [0.71 to1.0], p < 0.05). The optimal cut-off was 0.8. E_Adyn calculated from the echocardiographic estimation of the stroke volume variation and the invasive arterial pulse pressure variation can be used to discriminate pressure response to norepinephrine weaning. Agreement between E_Adyn calculated from echocardiography and thermodilution was poor. Echocardiographic E_Adyn might be used at bedside to optimize hemodynamic treatment.

Anaesthesia and ICU sedation with sevoflurane do not reduce myocardial injury in patients undergoing cardiac surgery: A randomized prospective study

BACKGROUND

To evaluate the effect of anaesthesia and ICU sedation with sevoflurane to protect the myocardium against ischemia-reperfusion injury associated to cardiac surgery assessed by troponin release.

METHODS

We performed a prospective, open-label, randomized study in cardiac surgery with cardiopulmonary bypass. Patients were randomized to an algorithm-based intervention group and a control group. The main outcome was the perioperative kinetic of cardiac troponin I (cTnI). The secondary outcomes included composite endpoint, GDF-15 (macrophage inhibitory cytokine-1) value, arterial lactate levels, and the length of stay (LOS) in the ICU.

RESULTS

Of 82 included patients, 81 were analyzed on an intention-to-treat basis (intervention group: n = 42; control group: n = 39). On inclusion, the intervention and control groups did not differ significantly in terms of demographic and surgical data. The postoperative kinetics of cTnI did not differ significantly between groups: the mean difference was 0.44 ± 1.09 μg/ml, P = .69. Incidence of composite endpoint and GDF-15 values were higher in the sevoflurane group than in propofol group. The intervention and control groups did not differ significantly in terms of ICU stay and hospital stay.

CONCLUSION

The use of an anaesthesia and ICU sedation with sevoflurane was not associated with a lower incidence of myocardial injury assessed by cTnI. Sevoflurane administration was associated with higher prevalence of acute renal failure and higher GDF-15 values.

Pupillometry pain index decreases intraoperative sufentanyl administration in cardiac surgery: a prospective randomized study

Pupillometry has proven effective for the monitoring of intraoperative analgesia in non-cardiac surgery. We performed a prospective randomized study to evaluate the impact of an analgesia-guided pupillometry algorithm on the consumption of sufentanyl during cardiac surgery. Fifty patients were included prior to surgery. General anesthesia was standardized with propofol and target-controlled infusions of sufentanyl. The standard group consisted of sufentanyl target infusion left to the discretion of the anesthesiologist. The intervention group consisted of sufentanyl target infusion based on the pupillary pain index. The primary outcome was the total intraoperative sufentanyl dose. The total dose of sufentanyl was lower in the intervention group than in the control group and (55.8 µg [39.7–95.2] vs 83.9 µg [64.1–107.0], p = 0.04). During the postoperative course, the cumulative doses of morphine (mg) were not significantly different between groups (23 mg [15–53] vs 24 mg [17–46]; p = 0.95). We found no significant differences in chronic pain at 3 months between the 2 groups (0 (0%) vs 2 (9.5%) p = 0.49). Overall, the algorithm based on the pupillometry pain index decreased the dose of sufentanyl infused during cardiac surgery.

Clinical trial number: NCT03864016.

Fluid expansion improve ventriculo-arterial coupling in preload-dependent patients: a prospective observational study

BACKGROUND

The objectives of the present study was to evaluate the effect of fluid challenge (FC) on ventriculo-arterial (V-A) coupling, its determinants: arterial elastance and ventricular elastance, and ability to predict fluid responsiveness.

METHODS

Thirty patients admitted to cardio-thoracic ICU in whom the physician decided to perform FC were included. Arterial pressure, cardiac output, arterial elastance, and ventricular elastance, were measured before and after FC with 500 ml of lactated Ringer's solution. Fluid responders were defined as patients with more than a 15% increase in stroke volume. V-A coupling was evaluated by the arterial elastance to ventricular elastance ratio.

RESULTS

Twenty-three (77%) of the 30 patients included in the study were fluid responders. Before FC, responders had higher arterial elastance and arterial elastance to ventricular elastance ratio. FC significantly increased mean arterial pressure, stroke volume and cardiac output, and significantly decreased systemic vascular resistance, arterial elastance and consequently the arterial elastance to ventricular elastance ratio. Changes in arterial elastance were correlated with changes in stroke volume, systemic vascular resistance, and arterial compliance. Baseline arterial elastance to ventricular elastance ratio over 1.4 predicted fluid responsiveness (area under the curve [95% confidence interval]: 0.84 [0.66-1]; p < 0.0001).

CONCLUSIONS

Fluid responsiveness patients had V-A coupling characterized by increase arterial elastance to ventricular elastance ratio, in relation to an increase arterial elastance. Fc improved the V-A coupling ratio by decreasing arterial elastance without altering ventricular elastance. Arterial elastance changes were related to those of systemic vascular resistance (continue component) and of arterial compliance (pulsatile component).

Dynamic Arterial Elastance as a Ventriculo-Arterial Coupling Index: An Experimental Animal Study

Dynamic arterial elastance (Ea_dyn), the ratio between arterial pulse pressure and stroke volume changes during respiration, has been postulated as an index of the coupling between the left ventricle (LV) and the arterial system. We aimed to confirm this hypothesis using the gold-standard for defining LV contractility, afterload, and evaluating ventricular-arterial (VA) coupling and LV efficiency during different loading and contractile experimental conditions. Twelve Yorkshire healthy female pigs submitted to three consecutive stages with two opposite interventions each: changes in afterload (phenylephrine/nitroprusside), preload (bleeding/fluid bolus), and contractility (esmolol/dobutamine). LV pressure-volume data was obtained with a conductance catheter, and arterial pressures were measured via a fluid-filled catheter in the proximal aorta and the radial artery. End-systolic elastance (Ees), a load-independent index of myocardial contractility, was calculated during an inferior vena cava occlusion. Effective arterial elastance (Ea, an index of LV afterload) was calculated as LV end-systolic pressure/stroke volume. VA coupling was defined as the ratio Ea/Ees. LV efficiency (LV_eff) was defined as the ratio between stroke work and the LV pressure-volume area. Ea_dyn was calculated as the ratio between the aortic pulse pressure variation (PPV) and conductance-derived stroke volume variation (SVV). A linear mixed model was used for evaluating the relationship between Ees, Ea, VA coupling, LV_eff with Ea_dyn. Ea_dyn was inversely related to VA coupling and directly to LV_eff. The higher the Ea_dyn, the higher the LV_eff and the lower the VA coupling. Thus, Ea_dyn, an easily measured parameter at the bedside, may be of clinical relevance for hemodynamic assessment of the unstable patient.

Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: a prospective bicentre study

BACKGROUND

Dynamic arterial elastance (Eadyn), defined as the ratio between pulse pressure variations and stroke volume variations, has been proposed to assess functional arterial load. We evaluated the evolution of Eadyn during volume expansion and the effects of neosynephrine infusion in hypotensive and preload-responsive patients.

METHODS

In this prospective bicentre study, we included 56 mechanically ventilated patients in the operating room. Each patient had volume expansion and neosynephrine infusion. Stroke volume and stroke volume variations were obtained using esophageal Doppler, and pulse pressure variations were measured through the arterial line. Pressure response to volume expansion was defined as an increase in mean arterial pressure (MAP) ≥ 10%.

RESULTS

Twenty-one patients were pressure responders to volume expansion. Volume expansion induced a decrease in Eadyn (from 0.69 [0.58-0.85] to 0.59 [0.42-0.77]) related to a decrease in pulse pressure variations more pronounced than the decrease in stroke volume variations. Baseline and changes in Eadyn after volume expansion were related to age, history of arterial hypertension, net arterial compliance and effective arterial elastance. Eadyn value before volume expansion > 0.65 predicted a MAP increase ≥ 10% with a sensitivity of 76% (95% CI 53-92%) and a specificity of 60% (95% CI 42-76%). Neosynephrine infusion induced a decrease in Eadyn (from 0.67 [0.48-0.80] to 0.54 [0.37-0.68]) related to a decrease in pulse pressure variations more pronounced than the decrease in stroke volume variations. Baseline and changes in Eadyn after neosynephrine infusion were only related to heart rate.

CONCLUSION

Eadyn is a potential sensitive marker of arterial tone changes following vasopressor infusion.

Reduced Rank Least Squares for Real-Time Short Term Estimation of Mean Arterial Blood Pressure in Septic Patients Receiving Norepinephrine

Norepinephrine (NE), an endogenous catecholamine, is a mainstay treatment for septic shock, which is a life-threatening manifestation of severe infection. NE counteracts the loss in blood pressure associated with septic shock. However, an NE infusion that is too low fails to counteract the blood pressure drop, and an NE infusion that is too high can cause a hypertensive crisis and heart attack. Ideally, the NE infusion rate should maintain a patient’s mean arterial blood pressure (MAP) above 65 mmHg. There are a few data-driven, quantitative models to predict the MAP, and incorporate NE effects. This paper presents a model, driven by intensive care unit (ICU) measurable data and known NE inputs, to predict the future MAP of an ICU patient. We derive a least square estimation model for MAP based on available ICU data, including heart period, NE infusion rate, and respiration wave. We learn the parameters of our model from initial patient data and then use this information to predict future MAP data. We assess our model with data from 12 septic patients. Our model successfully predicts and tracks MAP when the NE infusion rate changes. Specifically, we predict MAP 3 to 20 min in the future with the mean error of less than 4 to 7 mmHg over 12 patients. Conclusion: this new approach creates the potential to advance methods for predicting NE infusion rate in septic patients. Significance: successfully predicted patients’ MAP could reduce catastrophic human error and lessen clinicians’ workload.

Cardiovascular determinants of resuscitation from sepsis and septic shock

BACKGROUND

We hypothesized that the cardiovascular responses to Surviving Sepsis Guidelines (SSG)-defined resuscitation are predictable based on the cardiovascular state.

METHODS

Fifty-five septic patients treated by SSG were studied before and after volume expansion (VE), and if needed norepinephrine (NE) and dobutamine. We measured mean arterial pressure (MAP), cardiac index (CI), and right atrial pressure (Pra) and calculated pulse pressure and stroke volume variation (PPV and SVV), dynamic arterial elastance (Ea_dyn), arterial elastance (Ea) and left ventricular (LV) end-systolic elastance (Ees), Ees/Ea (VAC), LV ejection efficiency (LVeff), mean systemic pressure analogue (Pmsa), venous return pressure gradient (Pvr), and cardiac performance (Eh), using standard formulae.

RESULTS

All patients were hypotensive (MAP 56.8 ± 3.1 mmHg) and tachycardic (113.1 ± 7.5 beat min^-1), with increased lactate levels (lactate = 5.0 ± 4.2 mmol L^-1) with a worsened VAC. CI was variable but > 2 L min^-1 M^-2 in 74%. Twenty-eight-day mortality was 48% and associated with admission lactate, blood urea nitrogen (BUN), and creatinine levels but not cardiovascular state. In all patients, both MAP and CI improved following VE, as well as cardiac contractility (Ees). Fluid administration improved Pra, Pmsa, and Pvr in all patients, whereas both HR and Ea decreased after VE, thus normalizing VAC. CI increases were proportional to baseline PPV and SVV. CI increases proportionally decreased PPV and SVV. VE increased MAP > 65 mmHg in 35/55 patients. MAP responders had higher PPV, SVV, and Ea_dyn than non-responders. NE was given to 20/55 patients in septic shock, but increased MAP > 65 mmHg in only 12. NE increased Ea, Ea_dyn, Pra, Pmsa, and VAC while decreasing HR, PPV, SVV, and LVeff. MAP responders had higher pre-NE Ees and lower VAC. Dobutamine was given to 6/8 patients who remained hypotensive following NE. It increased Ees, MAP, CI, and LVeff, while decreasing HR, Pra, and VAC. At all times and all steps of the protocol, CI changes were proportional to Pvr changes independent of treatment.

CONCLUSIONS

The cardiovascular response to SSG-based resuscitation is highly heterogeneous but predictable from pre-treatment measures of cardiovascular state.

Dynamic arterial elastance measured by uncalibrated pulse contour analysis predicts arterial-pressure response to a decrease in norepinephrine

BACKGROUND

Dynamic arterial elastance (Ea_dyn) has been proposed as an indicator of vascular tone that predicts the decrease in arterial pressure in response to changes in norepinephrine (NE). The purpose of this study was to determine whether Ea_dyn measured by uncalibrated pulse contour analysis (UPCA) can predict a decrease in arterial pressure when the NE dosage is decreased.

METHODS

We conducted a prospective study in a university hospital intensive care unit. Patients with vasoplegic syndrome for whom the intensive care physician planned to decrease the NE dosage were included. Haemodynamic and UPCA (VolumeView and FloTrac; Edwards Lifesciences, Irvine, CA, USA) values were obtained before and after decreasing the NE dosage. Responders were defined by a >10% decrease in mean arterial pressure (MAP).

RESULTS

Of 35 patients included, 11 (31%) were pressure responders with a median decrease of 13%. Ea_dyn was correlated to systolic arterial pressure (SAP) (r=0.255; P=0.033), diastolic arterial pressure (r=0.271; P=0.024), MAP (r=0.310; P=0.009), heart rate (r=0.543; P=0.0001), and transthoracic echography cardiac output (r=0.264; P=0.024). Baseline Ea_dyn was correlated with MAP changes (r=0.394; P=0.019) and SAP changes (r=0.431; P=0.009). Ea_dyn predicted the decrease in arterial pressure with an area under the receiver-operating-characteristic curve of 0.84 (95% confidence interval: 0.70-0.97). The best cut-off was 0.90.

CONCLUSIONS

The present study confirms the ability of Ea_dyn measured by UPCA to predict an arterial pressure response to a decrease in NE. Ea_dyn may constitute an easy-to-use functional approach to arterial tone assessment regardless of the monitor used to measure its determinant.

CLINICAL TRIAL REGISTRATION

DRCIT95.

Postoperative Vasoplegic Syndrome Is Associated With Impaired Endothelial Vasomotor Response in Cardiac Surgery: A Prospective, Observational Study

OBJECTIVES

Vasoplegic syndrome (VS) affects up to 30% of cardiac surgery patients. Onset of VS may be associated with overproduction of nitric oxide (NO). The response of the brachial artery to NO can be assessed using flow-mediated vasodilation (FMD). The aim of this study was to assess brachial artery diameter and FMD response immediately after cardiac surgery.

DESIGN

Prospective, observational study.

SETTING

Single-center study in a tertiary teaching hospital.

PATIENTS

Patients older than 18 years undergoing elective cardiac surgery with cardiopulmonary bypass who provided informed consent.

INTERVENTIONS

Brachial artery diameter and FMD response were measured before cardiac surgery and just after surgery on admission to the intensive care unit. Patients were screened for VS for the following 48 hours.

RESULTS

Eleven (39%) of the 28 patients included in the study developed VS. Brachial artery diameter and FMD differed between VS and non-VS patients. On intensive care unit admission, mean (± standard deviation) brachial artery diameter was greater in VS patients than in non-VS patients (3.9 ± 0.7 mm v 3.0 ± 0.8 mm, respectively; p = 0.002). Similarly, the FMD response after surgery was greater in VS patients than in non-VS patients (42% ± 8% v 31% ± 1%, respectively; p = 0.014). Brachial artery diameter and FMD response after surgery were both predictive of VS, with an area under the curve (95% confidence interval) of 0.850 (0.705-0.995) (p = 0.002) and 0.755 (0.56-0.95) (p = 0.047), respectively.

CONCLUSION

Cardiac surgery with cardiopulmonary bypass appears to alter the NO-mediated endothelial vasomotor response.

Ventriculo-Arterial Coupling Analysis Predicts the Hemodynamic Response to Norepinephrine in Hypotensive Postoperative Patients: A Prospective Observational Study

OBJECTIVES

The objectives of the present study were to evaluate, in patients with persistent arterial hypotension in the immediate postcardiac surgery period, the effects of norepinephrine infusion on ventriculo-arterial coupling, its determinants: arterial elastance and end-systolic ventricular elastance, and to test the ability of arterial elastance to end-systolic ventricular elastance ratio to predict stroke volume increases.

DESIGN

Prospective observational study.

SETTING

Cardiac-vascular surgical ICU.

PATIENTS

Twenty-eight postoperative cardiac surgery patients, in whom physicians decided to administer norepinephrine infusion, were included.

MEASUREMENTS AND MAIN RESULTS

Arterial pressure, stroke volume index, cardiac index, indexed total peripheral resistance, arterial compliance, arterial elastance, and end-systolic ventricular elastance, were measured before and after norepinephrine infusion. We estimated ventriculo-arterial coupling by the arterial elastance to end-systolic ventricular elastance ratio and defined stroke volume responders by a stroke volume increase greater than or equal to 15%. Twenty-two of the 28 subjects had altered ventriculo-arterial coupling (1.87 [1.57-2.51] vs 1.1 [1-1.18]). Fifteen of the 28 subjects (54%) were stroke volume responders. At baseline, stroke volume responders had similar arterial pressure, higher indexed total peripheral resistance, arterial elastance, arterial elastance to end-systolic ventricular elastance ratio (2.21 [1.69-2.89] vs 1.33 [1.1-1.56]; p < 0.05), and lower arterial compliance, indexed total peripheral resistance and cardiac index. Norepinephrine significantly increased arterial pressure in all subjects. In stroke volume responders, norepinephrine increased arterial elastance, end-systolic ventricular elastance, cardiac index, and improved arterial elastance/end-systolic ventricular elastance coupling. The baseline arterial elastance to end-systolic ventricular elastance ratio predicted stroke volume responsiveness (area under the curve [95% CI], 0.87 [0.71-1]; p < 0.0001).

CONCLUSIONS

In patients with arterial hypotension norepinephrine increased end-systolic ventricular elastance and arterial elastance. The effects of norepinephrine on stroke volume depend on baseline ventriculo-arterial coupling. Although norepinephrine infusion corrects arterial hypotension in all subjects, increase of stroke volume occurred only in subjects with altered ventriculo-arterial coupling.