Pulse pressure and end-tidal carbon dioxide for monitoring low native cardiac output during veno-arterial ECLS: a prospective observational study

Oxygenation management during veno-arterial ECMO support for cardiogenic shock: a multicentric retrospective cohort study

BACKGOUND

Hyperoxemia is common and associated with poor outcome during veno-arterial extracorporeal membrane oxygenation (VA ECMO) support for cardiogenic shock. However, little is known about practical daily management of oxygenation. Then, we aim to describe sweep gas oxygen fraction (FSO2), postoxygenator oxygen partial pressure (PPOSTO2), inspired oxygen fraction (FIO2), and right radial arterial oxygen partial pressure (PaO2) between day 1 and day 7 of peripheral VA ECMO support. We also aim to evaluate the association between oxygenation parameters and outcome. In this retrospective multicentric study, each participating center had to report data on the last 10 eligible patients for whom the ICU stay was terminated. Patients with extracorporeal cardiopulmonary resuscitation were excluded. Primary endpoint was individual mean FSO2 during the seven first days of ECMO support (FSO2 mean (day 1-7)).

RESULTS

Between August 2019 and March 2022, 139 patients were enrolled in 14 ECMO centers in France, and one in Switzerland. Among them, the median value for FSO2 mean (day 1-7) was 70 [57; 79] % but varied according to center case volume. Compared to high volume centers, centers with less than 30 VA-ECMO runs per year were more likely to maintain FSO2 ≥ 70% (OR 5.04, CI 95% [1.39; 20.4], p = 0.017). Median value for right radial PaO2 mean (day 1-7) was 114 [92; 145] mmHg, and decreased from 125 [86; 207] mmHg at day 1, to 97 [81; 133] mmHg at day 3 (p < 0.01). Severe hyperoxemia (i.e. right radial PaO2 ≥ 300 mmHg) occurred in 16 patients (12%). PPOSTO2, a surrogate of the lower body oxygenation, was measured in only 39 patients (28%) among four centers. The median value of PPOSTO2 mean (day 1-7) value was 198 [169; 231] mmHg. By multivariate analysis, age (OR 1.07, CI95% [1.03-1.11], p < 0.001), FSO2 mean (day 1-3)(OR 1.03 [1.00-1.06], p = 0.039), and right radial PaO2 mean (day 1-3) (OR 1.03, CI95% [1.00-1.02], p = 0.023) were associated with in-ICU mortality.

CONCLUSION

In a multicentric cohort of cardiogenic shock supported by VA ECMO, the median value for FSO2 mean (day 1-7) was 70 [57; 79] %. PPOSTO2 monitoring was infrequent and revealed significant hyperoxemia. Higher FSO2 mean (day 1-3) and right radial PaO2 mean (day 1-3) were independently associated with in-ICU mortality.

The physiology of venoarterial extracorporeal membrane oxygenation - A comprehensive clinical perspective

Venoarterial extracorporeal membrane oxygenation (VA ECMO) has become a standard of care for severe cardiogenic shock, refractory cardiac arrest and related impending multiorgan failure. The widespread clinical use of this complex temporary circulatory support modality is still contrasted by a lack of formal scientific evidence in the current literature. This might at least in part be attributable to VA ECMO related complications, which may significantly impact on clinical outcome. In order to limit adverse effects of VA ECMO as much as possible an indepth understanding of the complex physiology during extracorporeally supported cardiogenic shock states is critically important. This review covers all relevant physiological aspects of VA ECMO interacting with the human body in detail. This, to provide a solid basis for health care professionals involved in the daily management of patients supported with VA ECMO and suffering from cardiogenic shock or cardiac arrest and impending multiorgan failure for the best possible care.

Impact of hyperoxia on the gut during critical illnesses

Molecular oxygen is typically delivered to patients via oxygen inhalation or extracorporeal membrane oxygenation (ECMO), potentially resulting in systemic hyperoxia from liberal oxygen inhalation or localized hyperoxia in the lower body from peripheral venoarterial (VA) ECMO. Consequently, this exposes the gastrointestinal tract to excessive oxygen levels. Hyperoxia can trigger organ damage due to the overproduction of reactive oxygen species and is associated with increased mortality. The gut and gut microbiome play pivotal roles in critical illnesses and even small variations in oxygen levels can have a dramatic influence on the physiology and ecology of gut microbes. Here, we reviewed the emerging preclinical evidence which highlights how excessive inhaled oxygen can provoke diffuse villous damage, barrier dysfunction in the gut, and gut dysbiosis. The hallmark of this dysbiosis includes the expansion of oxygen-tolerant pathogens (e.g., Enterobacteriaceae) and the depletion of beneficial oxygen-intolerant microbes (e.g., Muribaculaceae). Furthermore, we discussed potential impact of oxygen on the gut in various underlying critical illnesses involving inspiratory oxygen and peripheral VA-ECMO. Currently, the available findings in this area are somewhat controversial, and a consensus has not yet to be reached. It appears that targeting near-physiological oxygenation levels may offer a means to avoid hyperoxia-induced gut injury and hypoxia-induced mesenteric ischemia. However, the optimal oxygenation target may vary depending on special clinical conditions, including acute hypoxia in adults and neonates, as well as particular patients undergoing gastrointestinal surgery or VA-ECMO support. Last, we outlined the current challenges and the need for future studies in this area. Insights into this vital ongoing research can assist clinicians in optimizing oxygenation for critically ill patients.

Automated cardiac arrest detection using a photoplethysmography wristband: algorithm development and validation in patients with induced circulatory arrest in the DETECT-1 study

BACKGROUND

Unwitnessed out-of-hospital cardiac arrest is associated with low survival chances because of the delayed activation of the emergency medical system in most cases. Automated cardiac arrest detection and alarming using biosensor technology would offer a potential solution to provide early help. We developed and validated an algorithm for automated circulatory arrest detection using wrist-derived photoplethysmography from patients with induced circulatory arrests.

METHODS

In this prospective multicentre study in three university medical centres in the Netherlands, adult patients (aged 18 years or older) in whom short-lasting circulatory arrest was induced as part of routine practice (transcatheter aortic valve implantation, defibrillation testing, or ventricular tachycardia induction) were eligible for inclusion. Exclusion criteria were a known bilateral significant subclavian artery stenosis or medical issues interfering with the wearing of the wristband. After providing informed consent, patients were equipped with a photoplethysmography wristband during the procedure. Invasive arterial blood pressure and electrocardiography were continuously monitored as the reference standard. Development of the photoplethysmography algorithm was based on three consecutive training cohorts. For each cohort, patients were consecutively enrolled. When a total of 50 patients with at least one event of circulatory arrest were enrolled, that cohort was closed. Validation was performed on the fourth set of included patients. The primary outcome was sensitivity for the detection of circulatory arrest.

FINDINGS

Of 306 patients enrolled between March 14, 2022, and April 21, 2023, 291 patients were included in the data analysis. In the development phase (n=205), the first training set yielded a sensitivity for circulatory arrest detection of 100% (95% CI 94-100) and four false positive alarms; the second training set yielded a sensitivity of 100% (94-100), with six false positive alarms; and the third training set yielded a sensitivity of 100% (94-100), with two false positive alarms. In the validation phase (n=86), the sensitivity for circulatory arrest detection was 98% (92-100) and 11 false positive circulatory arrest alarms. The positive predictive value was 90% (95% CI 82-94).

INTERPRETATION

The automated detection of induced circulatory arrests using wrist-derived photoplethysmography is feasible with good sensitivity and low false positives. These promising findings warrant further development of this wearable technology to enable automated cardiac arrest detection and alarming in a home setting.

FUNDING

Dutch Heart Foundation (Hartstichting).

The Use of End-Tidal CO2 and Integrated Pulmonary Index to Predict Postspinal Hypotension in Cesarean Section

Early diagnosis and treatment of postspinal hypotension (PSH) in obstetric anaesthesia reduces the risk of maternofetal complications. In this study, the effect of EtCO2 and the integrated pulmonary index (IPI) in predicting PSH was investigated. Patients scheduled for cesarean section under spinal anaesthesia were included. The Capnostream 35 respiratory monitor (Medtronic, Inc., Dublin, Ireland) was used for EtCO2 and IPI. PSH developed in 52 (63.4%) of the 82 patients. EtCO2 and IPI values decreased significantly compared with baseline values in patients who developed PSH. There were statistically significant differences in EtCO2 (p = 0.001) and the IPI change (p = 0.045) in patients who developed PSH compared with those who did not. It was found that the EtCO2 difference had an independent effect on predicting PSH (p < 0.05), whereas the IPI difference did not (p > 0.05). One unit decrease in EtCO2 from the baseline increased the risk of PSH by 3.3 times. ROC curve analysis showed that the magnitude of change in EtCO2 was diagnostic for predicting PSH (AUC: 0.90 (0.83-0.97; p < 0.001)). IPI showed no predictive value for postspinal hypotension in cesarean section. However, EtCO2 monitoring, which is non-invasive and real-time monitoring, can be used to predict postspinal hypotension.

Unloading the Left Ventricle in Venoarterial ECMO: In Whom, When, and How?

Venoarterial extracorporeal membrane oxygenation provides cardiorespiratory support to patients in cardiogenic shock. This comes at the cost of increased left ventricle (LV) afterload that can be partly ascribed to retrograde aortic flow, causing LV distension, and leads to complications including cardiac thrombi, arrhythmias, and pulmonary edema. LV unloading can be achieved by using an additional circulatory support device to mitigate the adverse effects of mechanical overload that may increase the likelihood of myocardial recovery. Observational data suggest that these strategies may improve outcomes, but in whom, when, and how LV unloading should be employed is unclear; all techniques require balancing presumed benefits against known risks of device-related complications. This review summarizes the current evidence related to LV unloading with venoarterial extracorporeal membrane oxygenation.

Multi-Lobar Atelectasis in Children Receiving Venoarterial Extracorporeal Membrane Oxygenation for Cardiac Indications

BACKGROUND

Respiratory complications are common in patients who require venoarterial (VA) extracorporeal membrane oxygenation (ECMO) for cardiac indications. We aimed to examine the frequency and characteristics of patients who develop multi-lobar atelectasis early in the course of VA ECMO and to identify factors associated with its occurrence.

METHODS

We performed a single-center retrospective review of consecutive pediatric subjects on VA ECMO in the cardiovascular ICU from 2014 to 2019. Chest radiographs before VA ECMO initiation and daily for up to 5 d of VA ECMO support were reviewed. Multi-lobar atelectasis was defined as the collapse of ≥2 lobes of the same lung. Patients with multi-lobar atelectasis before or immediately after VA ECMO cannulation were excluded. Bivariate comparisons and multivariable logistic regression analyses were performed to identify factors independently associated with lung collapse. Results of the multivariable analysis are provided as odds ratio (OR) with 95% CI.

RESULTS

We reviewed 119 VA ECMO runs in 101 unique subjects. Multi-lobar atelectasis occurred in 36 runs (30%), with an isolated collapse of the left lung occurring most frequently (no. runs = 20). VA ECMO runs complicated by multi-lobar atelectasis were significantly longer and associated with lower hospital survival (51% vs 77%, survival in subjects without multi-lobar atelectasis; P = .01). Multivariable logistic regression analysis identified a subsequent ECMO run during the same admission to be independently associated with multi-lobar atelectasis (OR 5.4, 95% CI 1.2-21.5). Subanalysis of the subjects with isolated left lung collapse revealed male sex (OR 8.9, 95% CI 1.6-48.2) and subsequent ECMO run during the same admission (OR 4.0, 95% CI 1.2-13.6) to be independently associated with this complication, and mechanical ventilation at least 12 h before ECMO may be protective (OR 0.22, 95% CI 0.07-0.76).

CONCLUSIONS

Multi-lobar atelectasis commonly occurred in children who were receiving VA ECMO for cardiac failure and was associated with worse outcomes. Male patients, a subsequent VA ECMO run during the same hospitalization, and patients in whom mechanical ventilation was initiated shortly before ECMO cannulation may be at increased risk for this complication.

Determinants of Arterial Pressure of Oxygen and Carbon Dioxide in Patients Supported by Veno-Arterial ECMO

Background: The present study aimed to assess the determinants of arterial partial pressure of oxygen (PaO₂) and carbon dioxide (PaCO₂) in the early phase of veno-arterial extracorporeal membrane oxygenation (VA ECMO) support. Even though the guidelines considered both the risks of hypoxemia and hyperoxemia during ECMO support, there are a lack of data concerning the patients supported by VA ECMO. Methods: This is a retrospective, monocentric, observational cohort study in a university-affiliated cardiac intensive care unit. Hemodynamic parameters, ECMO parameters, ventilator settings, and blood gas analyses were collected at several time points during the first 48 h of VA ECMO support. For each timepoint, the blood samples were drawn simultaneously from the right radial artery catheter, VA ECMO venous line (before the oxygenator), and from VA ECMO arterial line (after the oxygenator). Univariate followed by multivariate mixed-model analyses were performed for longitudinal data analyses. Results: Forty-five patients with femoro-femoral peripheral VA ECMO were included. In multivariate analysis, the patients' PaO₂ was independently associated with Q_EC, F_DO₂, and time of measurement. The patients' PaCO₂ was associated with the sweep rate flow and the P_preCO₂. Conclusions: During acute VA ECMO support, the main determinants of patient oxygenation are determined by VA ECMO parameters.

Hyperoxia during extracorporeal cardiopulmonary resuscitation for refractory cardiac arrest is associated with severe circulatory failure and increased mortality

Background

High levels of arterial oxygen pressures (PaO₂) have been associated with increased mortality in extracorporeal cardiopulmonary resuscitation (ECPR), but there is limited information regarding possible mechanisms linking hyperoxia and death in this setting, notably with respect to its hemodynamic consequences. We aimed therefore at evaluating a possible association between PaO₂, circulatory failure and death during ECPR.

Methods

We retrospectively analyzed 44 consecutive cardiac arrest (CA) patients treated with ECPR to determine the association between the mean PaO₂ over the first 24 h, arterial blood pressure, vasopressor and intravenous fluid therapies, mortality, and cause of deaths.

Results

Eleven patients (25%) survived to hospital discharge. The main causes of death were refractory circulatory shock (46%) and neurological damage (24%). Compared to survivors, non survivors had significantly higher mean 24 h PaO₂ (306 ± 121 mmHg vs 164 ± 53 mmHg, p < 0.001), lower mean blood pressure and higher requirements in vasopressors and fluids, but displayed similar pulse pressure during the first 24 h (an index of native cardiac recovery). The mean 24 h PaO₂ was significantly and positively correlated with the severity of hypotension and the intensity of vasoactive therapies. Patients dying from circulatory failure died after a median of 17 h, compared to a median of 58 h for patients dying from a neurological cause. Patients dying from neurological cause had better preserved blood pressure and lower vasopressor requirements.

Conclusion

In conclusion, hyperoxia is associated with increased mortality during ECPR, possibly by promoting circulatory collapse or delayed neurological damage.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02361-3.

Impact of pulse pressure on clinical outcome in extracorporeal cardiopulmonary resuscitation (eCPR) patients

BACKGROUND

Hemodynamic response to successful extracorporeal cardiopulmonary resuscitation (eCPR) is not uniform. Pulse pressure (PP) as a correlate for myocardial damage or recovery from it, might be a valuable tool to estimate the outcome of these patients.

METHODS

We report retrospective data of a single-centre registry of eCPR patients, treated at the Interdisciplinary Medical Intensive Care Unit at the Medical Centre, University of Freiburg, Germany, between 01/2017 and 01/2020. The association between PP of the first 10 days after eCPR and hospital survival was investigated. Moreover, patients were divided into three groups according to their PP [low (0-9 mmHg), mid (10-29 mmHg) and high (≥ 30 mmHg)] at each time point.

RESULTS

One hundred forty-three patients (age 63 years, 74.1% male, 40% OHCA, average low flow time 49 min) were analysed. Overall hospital survival rate was 28%. A low PP both early after eCPR (after 1, 3, 6 and 12 h) and after day 1 to day 8 was associated with reduced hospital survival. At each time point (1 h to day 5) the classification of patients into a low, mid and high PP group was able to categorize the patients for a low (5-20%), moderate (20-40%) and high (50-70%) survival rate. A multivariable analysis showed that the mean PP of the first 24 h was an independent predictor for survival (p = 0.008).

CONCLUSION

In this analysis, PP occurred to be a valuable parameter to estimate survival and maybe support clinical decision making in the further course of patients after eCPR.