Improving ventricular-arterial coupling during resuscitation from shock: effects on cardiovascular function and systemic perfusion

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.

Use and Implications of Echocardiography in the Hemodynamic Assessment of Cardiogenic Shock

Cardiogenic shock (CS) is a complex multisystem syndrome due to pump failure, associated with high mortality and morbidity. Its hemodynamic characterization is key to the diagnostic algorithm and management. Pulmonary artery catheterization is the gold standard for the left and right hemodynamic evaluation, but some concerns exist for invasivity and untoward mechanical and infective complications. Transthoracic echocardiography is a robust noninvasive diagnostic tool for hemodynamic multiparametric assessment that well applies to the management of CS. Its applications expand from etiology definition to the choice of therapeutic intervention and their monitoring. The present review aims at detailing the role of ultrasounds in CS emphasizing the clinical implications of combining cardiac and non-cardiac ultrasounds examinations that may correlate with prognosis.

Role of Electromechanical Dyssynchrony Assessment During Acute Circulatory Failure and Its Relation to Ventriculo-Arterial Coupling

Introduction

Two parallel paradigms of cardiovascular efficiency and haemodynamic optimisation coexist in haemodynamic research. Targeting ventriculo-arterial (VA) coupling [i.e., the ratio between arterial and ventricular elastance (E_V)] and electromechanical coupling are two promising approaches in acute circulatory failure. However, validation of the parameters of electromechanical coupling in critically ill patients is ongoing. Furthermore, a unifying link between VA and electromechanical coupling may exist, as E_V is correlated with different times of the cardiac cycle.

Materials and Methods

This study was a retrospective analysis of a prospectively collected observational database from one tertiary center ICU. We analyzed the relationship between electromechanical dyssynchrony and acute circulatory failure hemodynamics before and after treatment (i.e., fluid expansion, dobutamine, or norepinephrine infusion). The relationship between electromechanical coupling and VA coupling was also investigated. Adult patients with haemodynamic instability were included. Haemodynamic parameters, including arterial pressure, cardiac index, VA coupling, stroke work index/pressure–volume area (SWI/PVA), t-IVT, and Tei's index, were collected before and after treatment. A t-IVT of >12 s/min was classified as intraventricular dyssynchrony.

Results

We included 54 patients; 39 (72.2%) were classified as having intraventricular dyssynchrony at baseline. These patients with baseline dyssynchrony showed a statistically significant amelioration of t-IVT (from 18 ± 4 s to 14 ± 6 s, p = 0.001), left ventricular E_V [from 1.1 (0.72–1.52) to 1.33 (0.84–1.67) mmHg mL⁻¹, p = 0.001], VA coupling [from 2 (1.67–2.59) to 1.80 (1.40–2.21), p = 0.001], and SWI/PVA [from 0.58 (0.49–0.65) to 0.64 (0.51–0.68), p = 0.007]. Patients without baseline dyssynchrony showed no statistically significant results. The improvement in VA coupling was mediated by an amelioration of E_V. All patients improved their arterial pressure and cardiac index with treatment. The haemodynamic treatment group exhibited no effect on changing t-IVT.

Conclusion

Acute circulatory failure is associated with electromechanical dyssynchrony. Cardiac electromechanical coupling was improved by haemodynamic treatment only if altered at baseline. The improvement of cardiac electromechanical coupling was associated with the improvement of markers of cardiocirculatory efficacy and efficiency (i.e., SWI/PVA and VA coupling). This study was the first to demonstrate a possible link between cardiac electromechanical coupling and VA coupling in patients with acute circulatory failure.

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 >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 < 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.

Combining Physiology-Based Modeling and Evolutionary Algorithms for Personalized, Noninvasive Cardiovascular Assessment Based on Electrocardiography and Ballistocardiography

Purpose: This study proposes a novel approach to obtain personalized estimates of cardiovascular parameters by combining (i) electrocardiography and ballistocardiography for noninvasive cardiovascular monitoring, (ii) a physiology-based mathematical model for predicting personalized cardiovascular variables, and (iii) an evolutionary algorithm (EA) for searching optimal model parameters.

Methods: Electrocardiogram (ECG), ballistocardiogram (BCG), and a total of six blood pressure measurements are recorded on three healthy subjects. The R peaks in the ECG are used to segment the BCG signal into single BCG curves for each heart beat. The time distance between R peaks is used as an input for a validated physiology-based mathematical model that predicts distributions of pressures and volumes in the cardiovascular system, along with the associated BCG curve. An EA is designed to search the generation of parameter values of the cardiovascular model that optimizes the match between model-predicted and experimentally-measured BCG curves. The physiological relevance of the optimal EA solution is evaluated a posteriori by comparing the model-predicted blood pressure with a cuff placed on the arm of the subjects to measure the blood pressure.

Results: The proposed approach successfully captures amplitudes and timings of the most prominent peak and valley in the BCG curve, also known as the J peak and K valley. The values of cardiovascular parameters pertaining to ventricular function can be estimated by the EA in a consistent manner when the search is performed over five different BCG curves corresponding to five different heart-beats of the same subject. Notably, the blood pressure predicted by the physiology-based model with the personalized parameter values provided by the EA search exhibits a very good agreement with the cuff-based blood pressure measurement.

Conclusion: The combination of EA with physiology-based modeling proved capable of providing personalized estimates of cardiovascular parameters and physiological variables of great interest, such as blood pressure. This novel approach opens the possibility for developing quantitative devices for noninvasive cardiovascular monitoring based on BCG sensing.

Prognostic value of left ventricular-arterial coupling in elderly patients with septic shock

PURPOSE

To investigate the predictive value of left ventricular-arterial coupling (VAC) for clinical prognosis of elderly patients with septic shock.

MATERIALS AND METHODS

This was a single-center prospective cohort study of 63 elderly patients with septic shock treated between August 2014 and January 2016 at the 30-bed intensive care unit (ICU) of Zhejiang Hospital (China). Left VAC was evaluated by transthoracic echocardiography (TTE). End-systolic elastance (Ees) and left ventricular ejection fraction (LVEF) were measured; arterial elastance (Ea) was calculated. The 28-day survival was evaluated.

RESULTS

Compared with non-survivors, survivors had a significantly lower Ea/Ees ratio (P<0.01), mainly because survivors had higher Ees values (P<0.01), but without difference in Ea (P=0.720). LVEF was greater (47.5±7.3 vs. 43.6±6.4, P=0.03); LVESV was smaller in survivors compared to non-survivors (P<0.05). The multivariate Cox proportional regression analysis showed that APACHEII scores (hazard ratio (HR)=1.12, 95% confidence interval (95%CI):1.01-1.25, P=0.04), blood lactate levels (HR=1.21, 95%CI:1.07-1.36, P=0.002), and VAC (HR=2.57, 95%CI:1.29-5.13, P=0.007) were independently associated with 28-day mortality of elderly patients with septic shock. The optimal cutoff point of VAC for predicting 28-day mortality was 2.14 with 56.7% sensibility and 87.9% specificity; the area under the curve was 0.74.

CONCLUSIONS

Left VAC has prognostic value in elderly patients with septic shock.

Critical care considerations in the management of the trauma patient following initial resuscitation

Background

Care of the polytrauma patient does not end in the operating room or resuscitation bay. The patient presenting to the intensive care unit following initial resuscitation and damage control surgery may be far from stable with ongoing hemorrhage, resuscitation needs, and injuries still requiring definitive repair. The intensive care physician must understand the respiratory, cardiovascular, metabolic, and immunologic consequences of trauma resuscitation and massive transfusion in order to evaluate and adjust the ongoing resuscitative needs of the patient and address potential complications. In this review, we address ongoing resuscitation in the intensive care unit along with potential complications in the trauma patient after initial resuscitation. Complications such as abdominal compartment syndrome, transfusion related patterns of acute lung injury and metabolic consequences subsequent to post-trauma resuscitation are presented.

Methods

A non-systematic literature search was conducted using PubMed and the Cochrane Database of Systematic Reviews up to May 2012.

Results and conclusion

Polytrauma patients with severe shock from hemorrhage and massive tissue injury present major challenges for management and resuscitation in the intensive care setting. Many of the current recommendations for “damage control resuscitation” including the use of fixed ratios in the treatment of trauma induced coagulopathy remain controversial. A lack of large, randomized, controlled trials leaves most recommendations at the level of consensus, expert opinion. Ongoing trials and improvements in monitoring and resuscitation technologies will further influence how we manage these complex and challenging patients.

Validation of stroke work and ventricular arterial coupling as markers of cardiovascular performance during resuscitation

BACKGROUND

Resuscitation regimens based on stroke work index (SWI) and ventricular-arterial coupling (VAC) are controversial. The Signal Interpretation and Monitoring (SIMON) system continuously collects and stores physiologic intensive care unit (ICU) bedside data at 3- to 5-second intervals. The purpose of this study was to demonstrate the capabilities of a completely automated data management system by further evaluating SWI-based resuscitation.

METHODS

This study was a retrospective review of all severely injured patients requiring a pulmonary artery catheter (PAC) for acute postinjury resuscitation. Patients with a severe head injury were excluded. Hemodynamic (HD) data (21 million datapoints) were densely acquired and archived by SIMON. Mean values of HD variables were compared between survivors and nonsurvivors. Receiver operator characteristic (ROC) curves were constructed for HD variables. Threshold values which maximized sensitivity and specificity were determined.

RESULTS

Eighty-eight patients over a 19-month time period met criteria and were included in the analysis. SWI was significantly greater in survivors versus nonsurvivors (4421 +/- 1278 versus 3163 +/- 1066 mm Hg . mL/m, p = 0.0008). VAC was quantified by the ratio (RATIO) of afterload (Ea) to contractility (Ees). RATIO (Ea/Ees) in survivors was significantly better than in nonsurvivors (1.9 +/- 1.1 vs. 2.9 +/- 1.0, p = 0.002). ROC curves identified threshold values of 3250 mm Hg x mL/m for SWI and 2.1 for RATIO (AUC = 0.78 and 0.82, respectively).

CONCLUSION

Previous work demonstrating the use of SWI and VAC as resuscitation guidelines was supported through the use of a powerful ICU data management system (SIMON). The emergence of these "new vital signs" may change the way injured patients are evaluated and resuscitated in the ICU.

Effects of Dopamine and Olprinone on Ventricular Energetics in Sevoflurane-Induced Acute Left Ventricular Depression in Dogs

OBJECTIVE

The purpose of this study was to compare the effects of dopamine and a new phosphodiesterase (PDE)-3 inhibitor, olprinone, on hemodynamics and myocardial energetics in dogs with acute myocardial depression.

DESIGN

Prospective, randomized, crossover study.

SETTING

University animal laboratory.

SUBJECTS

Mongrel dogs.

INTERVENTIONS

Eight open-chest, barbiturate-anesthetized dogs with instruments for measurement of left ventricular pressure and volume were exposed to 2 MAC (minimum alveolar concentration) of sevoflurane to induce acute myocardial depression. Each dog was randomly assigned for either infusion of dopamine (5 microg/kg/min) for 15 minutes or bolus of olprinone (10 microg/kg), followed by an infusion (0.3 microg/kg/min) for 30 minutes. Treatment was crossed over after a washout period of 90 minutes.

MEASUREMENTS AND MAIN RESULTS

For analysis of ventricular energetics, ventriculoarterial coupling was assessed using the ratio of arterial elastance to end-systolic pressure-volume relation and mechanical efficiency was calculated using the ratio of external work to pressure-volume area. Measurements were performed prior to sevoflurane administration, and before and after treatment. Two MAC of sevoflurane significantly impaired ventriculoarterial coupling and mechanical efficiency. Both olprinone and dopamine improved ventriculoarterial coupling and mechanical efficiency to similar degrees, but by different mechanisms. Olprinone improved ventricular energetics at a lower energy expenditure, probably because of olprinone's vasodilating effect, which augments energy transfer from the ventricle into the systemic circulation.

CONCLUSION

Although both dopamine and olprinone improve sevoflurane-induced impairment of ventricular energetics, olprinone accomplishes this with lower ventricular energy expenditure.

PRELOAD OPTIMIZATION USING “STARLING CURVE” GENERATION DURING SHOCK RESUSCITATION: CAN IT BE DONE?

Preload-directed resuscitation is the standard of care in U.S. trauma centers. As part of our standardized protocol for traumatic shock resuscitation, patients who do not respond to initial interventions of hemoglobin replacement and fluid volume loading have optimal preload determined using a standardized algorithm to generate a "Starling curve." We retrospectively analyzed data from 147 consecutive resuscitation protocol patients during the 24 months ending August 2002. Fifty (34%) of these patients required preload optimization, of which the optimization algorithm was completed in 36 (72%). The average age of those who required preload optimization was 44 +/- 3 years vs. 34 +/- 1 years for patients who did not. Execution of the algorithm caused PCWP to increase from 18 +/- 1 mmHg to a maximum of 25 +/- 2 mmHg and CI to increase from 3.2 +/- 0.1 L/min m(-2) to 4.5 +/- 0.4 L/min m(-2). Algorithm logic determined PCWP = 24 +/- 2 to be optimal preload at the maximum CI = 4.8 +/- 0.4, and as the volume loading threshold for the remaining time of the resuscitation process. Starling curve preload optimization was begun 6.5 +/- 0.8 h after start of the resuscitation protocol and required 36 +/- 5 min and 4 +/- 0.4 fluid boluses (1.6 +/- 0.2 L). Comparison of early response of those patients who required preload optimization and those who did not indicated hemodynamic compromise apparent in the 1st 4 h of standardized resuscitation. We conclude that preload optimization using sequential fluid bolus and PCWP-CI measurement to generate a Starling curve is feasible during ICU shock resuscitation, but that there is the disadvantage that increasing and maintaining high PCWP may contribute to problematic tissue edema.