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

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.

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.

Prevalence of systemic venous congestion assessed by Venous Excess Ultrasound Grading System (VExUS) and association with acute kidney injury in a general ICU cohort: a prospective multicentric study

BACKGROUND

The importance of assessing venous congestion in ICU patients is widely acknowledged, but its study is hampered by the lack of a practical evaluation tool. The Venous Excess Ultrasound Grading System (VExUS), based on a semi-quantitative combined ultrasound assessment, has been associated with acute kidney injury (AKI) in cardiac ICU patients. The objectives of this study were to assess the prevalence of congestion using VExUS in general ICU patients, and to evaluate the association between VExUS, AKI and death.

METHODS

This prospective, observational study included adult patients within 24 h of ICU admission. VExUS and hemodynamic parameters were measured four times during the ICU stay: within 24 h of ICU admission, after day 1 (between 24 and 48 h), after day 2 (between 48 and 72 h), and last day of ICU stay. The prevalence of AKI during the first week in ICU and 28-day mortality were assessed.

RESULTS

Among the 145 patients included, the percentage of patients with a VExUS score of 2 (moderate congestion) and 3 (severe congestion) was 16% and 6%, respectively. The prevalence did not change over the study period. There was no significant association between admission VExUS scores and AKI (p = 0.136) or 28-day mortality (p = 0.594). Admission VExUS ≥ 2 was not associated with AKI (OR 0.499, CI_95% 0.21-1.17, p = 0.109) nor 28-day mortality (OR 0.75, CI_95% 0.2-2.8, p = 0.669). The results were similar for VExUS scores measured at day 1 and day 2.

CONCLUSIONS

In general ICU cohort the prevalence of moderate to severe venous congestion was low. Early assessment of systemic venous congestion using VExUS scores was not associated with the development of AKI or with 28-day mortality.

Diuretics depletion improves cardiac output and ventriculo-arterial coupling in congestive ICU patients during hemodynamic de-escalation

PURPOSE

Congestion was shown to hamper organ perfusion, but the exact timing of diuretic initiation during hemodynamic de-escalation in shock is unclear. The aim of this study was to describe the hemodynamic effects of diuretic initiation in the stabilized shock.

METHODS

We performed a monocentric, retrospective analysis, in a cardiovascular medico-surgical ICU. We included consecutive resuscitated adult patients, for whom the clinician decided to introduce loop diuretic treatment for clinical signs of fluid overload. The patients were hemodynamically evaluated at the moment of diuretic introduction and 24 h later.

RESULTS

Seventy ICU patients were included in this study, with a median duration of ICU stay before diuretic initiation of 2 [1-3] days. 51(73%) patients were classified as congestive (central venous pressure > 12 mmHg). After treatment, the cardiac index increased towards normal values in the congestive group (2.7 ± 0.8 L min^- 1 m^- 2 from 2.5 ± 0.8 L min^- 1 m^- 2, p = 0.042), but not in the non-congestive group (2.7 ± 0.7 L min^- 1 m^- 2 from baseline 2.7 ± 0.8 L min^- 1 m^- 2, p = 0.968). A decrease in arterial lactate concentrations was observed in the congestive group (2.1 ± 2 mmol L^- 1 vs. 1.3 ± 0.6 mmol L^- 1, p < 0.001). The diuretic therapy was associated with an improvement of ventriculo-arterial coupling comparing with baseline values in the congestive group (1.69 ± 1 vs. 1.92 ± 1.5, p = 0.03). The norepinephrine use decreased in congestive patients (p = 0.021), but not in the non-congestive group (p = 0.467).

CONCLUSION

The initiation of diuretics in ICU congestive patients with stabilized shock was associated with improvement of cardiac index, ventriculo-arterial coupling, and tissue perfusion parameter. These effects were not observed in non-congestive patients.

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.