Morbid obesity is not a contraindication to transport on extracorporeal support

Impact of obesity on outcomes of extracorporeal membrane oxygenation support: a systematic review and meta-analysis

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used when standard methods of standard treatment methods are not successful. Obese patients present unique challenges during ECMO due to large body size hindering sufficient flows, difficulties with patient positioning and anatomical landmark identification, and restricted radiology scans. This meta-analysis aims to investigate the impact of obesity on the outcomes of patients undergoing ECMO.

METHODS

Databases (PubMed, Embase, and Scopus databases) were searched to identify relevant studies published until July 2023. Data were reported as odds ratios (OR) with 95% confidence interval (CI), and the descriptive data were reported as standard difference of means (SDM) by a random effects model.

RESULTS

A literature search identified 345 studies. Of them, 18 studies met the inclusion criteria. The findings from the meta-analysis revealed no significant association between obesity and survival outcomes after ECMO (odds ratio (OR): 0.91, 95% confidence interval (CI): 0.70-1.17, p: 0.46). Moreover, no comparative significant differences were found between obese and non-obese individuals on the duration of ECMO procedure (standardized mean difference (SMD): 0.07, -0.03-0.17), length of hospital stay (-0.03, -0.19 to 0.12), and duration of ventilation support (-0.10, -0.44 to 0.24).

CONCLUSION

The meta-analysis findings suggest no significant impact of obesity on the survival outcomes after the ECMO procedure. There was no significant impact of obesity on the duration of ECMO procedures, length of hospital stay, and duration of ventilation support.

Obesity and Extracorporeal Membrane Oxygenation (ECMO): Analysis of Outcomes

Traditionally, patients with obesity have been deemed ineligible for extracorporeal life support (ELS) therapies such as extracorporeal membrane oxygenation (ECMO), given the association of obesity with chronic health conditions that contribute to increased morbidity and mortality. Nevertheless, a growing body of literature suggests the feasibility, efficacy, and safety of ECMO in the obese population. This review provides an in-depth analysis of the current literature assessing the effects of obesity on outcomes among patients supported with ECMO (venovenous [VV] ECMO in noncoronavirus disease 2019 and coronavirus disease 2019 acute respiratory distress syndrome, venoarterial [VA] ECMO, and combined VV and VA ECMO), offer a possible explanation of the current findings on the basis of the obesity paradox phenomenon, provides a framework for future studies addressing the use of ELS therapies in the obese patient population, and provides guidance from the literature for many of the challenges related to initiating, maintaining, and weaning ELS therapy in patients with obesity.

Should Obesity Be an Exclusion Criterion for Extracorporeal Membrane Oxygenation Support? A Scoping Review

Obesity is often considered a contraindication to extracorporeal membrane oxygenation (ECMO) candidacy due to technical challenges with vascular access, higher cardiac output requirements, and known associations between obesity and overall increased morbidity and mortality due to chronic health conditions. However, a growing body of literature suggests that ECMO may be as safe and efficacious in both obese and nonobese patients. This scoping review provides a synthesis of the available literature on the outcomes of obese patients supported with (1) venovenous (VV)-ECMO in acute respiratory distress syndrome (ARDS) not due to coronavirus disease 2019 (COVID-19), (2) VV-ECMO in ARDS due to COVID-19, (3) venoarterial (VA)-ECMO for all indications, and (4) studies combining data of patients supported with VA- and VV-ECMO. A librarian-assisted search was performed using 4 primary electronic medical databases (PubMed, Web of Science, Excerpta Medica database [Embase], and Cochrane Library) from January 2003 to March 2023. Articles that reported outcomes of obese patients requiring ECMO support were included. Two reviewers independently screened titles, abstracts, and full text of articles to determine eligibility. Data extraction was performed using customized fields established a priori within a systematic review software system. A total of 354 publications were imported for screening on titles and abstracts, and 30 studies were selected for full-text review. A total of 26 publications met the inclusion criteria: 7 on VV-ECMO support in non-COVID-19 ARDS patients, 6 on ECMO in COVID-19 ARDS patients, 8 in patients supported with VA-ECMO, and 5 combining both VA- and VV-ECMO data. Although the included studies are limited to retrospective analyses and display a heterogeneity in definitions of obesity and comparison groups, the currently available literature suggests that outcomes and complications of ECMO therapy are equivalent in obese patients as compared to nonobese patients. Hence, obesity as measured by body mass index alone should not be considered an exclusion criterion in the decision to initiate ECMO.

Subacute groin complications related to ECMO cannulation are associated with longer hospitalizations

Subacute groin complications associated with extracorporeal membrane oxygenation (ECMO) cannulation are well recognized, yet their effects on clinical outcomes remain unknown. This single-center, retrospective study reviewed all patients receiving venoarterial ECMO from 01/2017 to 02/2020. Cohorts analyzed included transplanted patients (TPs) and non-transplanted patients (N-TPs) who did or did not develop ECMO-related subacute groin complications. Standard descriptive statistics were used for comparisons. Logistic regressions identified associated risk factors. Overall, 82/367 (22.3%) ECMO patients developed subacute groin complications, including 25/82 (30.5%) seromas/lymphoceles, 32/82 (39.0%) hematomas, 18/82 (22.0%) infections, and 7/82 (8.5%) non-specified collections. Of these, 20/82 (24.4%) underwent surgical interventions, most of which were muscle flaps (14/20, 70.0%). TPs had a higher incidence of subacute groin complications than N-TPs (14/28, 50.0% vs. 68/339, 20.1%, P = 0.001). Seromas/lymphoceles more often developed in TPs than N-TPs (10/14, 71.4% vs. 15/68, 22.1%, P = 0.001). Most patients with subacute groin complications survived to discharge (60/68, 88.2%). N-TPs who developed subacute groin complications had longer post-ECMO lengths of stay than those who did not (34 days, IQR 16-53 days vs. 17 days, IQR 8-34 days, P < 0.001). Post-ECMO length of stay was also longer among patients who underwent related surgical interventions compared to those who did not (50 days, IQR 35-67 days vs. 29 days, IQR 16-49 days, P = 0.007). Transplantation was the strongest risk factor for developing subacute groin complications (OR 3.91, CI_95% 1.52-10.04, P = 0.005). Subacute groin complications and related surgical interventions are common after ECMO cannulation and are associated with longer hospital stays. When surgical management is warranted, muscle flaps may reduce lengths of stay compared to other surgical interventions.

Outcomes of extracorporeal membrane oxygenation following the 2018 adult heart allocation policy

Background

The purpose of the study was to characterize changes in waitlist and post-transplant outcomes of extracorporeal membrane oxygenation (ECMO) patients bridged to heart transplantation under the 2018 adult heart allocation policy.

Methods

All adult patients listed for isolated heart transplantation from August 2016 to December 2020 were identified using the United Network for Organ Sharing database. Patients were stratified into Eras (Era 1 and Era 2) centered around the policy change on October 18, 2018. Competing risk regression was used to evaluate waitlist death or deterioration across Eras. Cox proportional hazards models were used to determine associations between use of ECMO and 1-year post-transplant mortality within each Era.

Results

Of 8,902 heart transplants included in analysis, 339 (3.8%) were bridged with ECMO (Era 2: 6.1% vs Era 1: 1.2%, P<0.001). Patients bridged with ECMO in Era 2 were less frequently female (26.0% vs 42.0%, P = 0.02) and experienced shorter waitlist times (5 vs 11 days, P<0.001) along with a lower likelihood of waitlist death or deterioration (subdistribution hazard ratio, 0.45, 95% confidence interval, CI, 0.30–0.68, P<0.001) compared to those in Era 1. Use of ECMO was associated with increased post-transplant mortality at 1-year compared to all other transplants in Era 1 (hazard ratio 3.78, 95% CI 1.88–7.61, P < 0.001) but not Era 2.

Conclusions

Patients bridged with ECMO in Era 2 experience improved waitlist and post-transplant outcomes compared to Era 1, giving credence to the increased use of ECMO under the new allocation policy.

Effect of Body Mass Index on the Clinical Outcomes of Adult Patients Treated With Venoarterial ECMO for Cardiogenic Shock

OBJECTIVE

Current guidelines consider obesity to be a relative contraindication to venoarterial extracorporeal membrane oxygenation (VA-ECMO) for refractory cardiogenic shock. The authors investigated the effect of body mass index (BMI) on clinical outcomes in patients treated with VA-ECMO for cardiogenic shock.

DESIGN

This was a retrospective and observational study.

SETTING

University hospital.

PARTICIPANTS

The study comprised 150 adult patients who underwent VA-ECMO for cardiogenic shock.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was intensive care unit (ICU) mortality. Of the 150 included patients, 10 were underweight (BMI < 18.5 kg/m²), 62 were normal weight (BMI = 18.5-24.9 kg/m²), 34 were overweight (BMI = 25.0-29.9 kg/m²), 34 were obese class I (BMI = 30.0-34.9 kg/m²), and 10 were obese class II (BMI = 35.0-39.9 kg/m²). All-cause ICU mortality was 62% (underweight, 70%; normal weight, 53%; overweight, 65%; class I obese, 71%; class II obese, 70%). After multivariate logistic regression, BMI was not associated with ICU mortality (adjusted odds ratio [aOR] 0.99 [0.92-1.07], p = 0.8). Analysis by BMI category showed unfavorable mortality trends in underweight patients (aOR 3.58 [0.82-19.6], p = 0.11) and class I obese patients (aOR 2.39 [0.95-6.38], p = 0.07). No statistically significant differences were found among BMI categories in the incidences of complications.

CONCLUSION

The results suggested that BMI alone should not be considered an exclusion criterion for VA-ECMO. The unfavorable trend observed in underweight patients could be the result of malnutrition.

Extracorporeal Membrane Oxygenation Rescue for Severe Aspiration Pneumonitis in Two Patients after Roux-en-y Gastric Bypass Procedure

Roux-en-y gastric bypass (RYGB) is one of the most common weight loss surgical procedures performed in the United States. Early post-operative small bowel obstruction is a rare but potentially morbid, complication of RYGB. We report two patients who underwent RYGB and required subsequent treatment for a post-operative small bowel obstruction. Their post-operative course was complicated by severe aspiration pneumonitis leading to hypoxemic respiratory failure requiring rescue with femoral veno-venous extracorporeal membrane oxygenation (V-V ECMO). Both patients were successfully extubated, weaned off V-V ECMO support, and discharged to home. These cases highlight the potential role of V-V ECMO for patients who have undergone RYGB and develop severe aspiration pneumonitis. They also highlight the need for cautionary use of gastrografin in RYGB patients. Early engagement of a multidisciplinary team experienced with adult ECMO is vital for favorable patient outcomes.

The Impact of Obesity in Critical Illness

The prevalence of obesity is rising worldwide. Adipose tissue exerts anatomic and physiological effects with significant implications for critical illness. Changes in respiratory mechanics cause expiratory flow limitation, atelectasis, and V̇/Q̇ mismatch with resultant hypoxemia. Altered work of breathing and obesity hypoventilation syndrome may cause hypercapnia. Challenging mask ventilation and peri-intubation hypoxemia may complicate intubation. Patients with obesity are at increased risk of ARDS and should receive lung-protective ventilation based on predicted body weight. Increased positive end expiratory pressure (PEEP), coupled with appropriate patient positioning, may overcome the alveolar decruitment and intrinsic PEEP caused by elevated baseline pleural pressure; however, evidence is insufficient regarding the impact of high PEEP strategies on outcomes. Venovenous extracorporeal membrane oxygenation may be safely performed in patients with obesity. Fluid management should account for increased prevalence of chronic heart and kidney disease, expanded blood volume, and elevated acute kidney injury risk. Medication pharmacodynamics and pharmacokinetics may be altered by hydrophobic drug distribution to adipose depots and comorbid liver or kidney disease. Obesity is associated with increased risk of VTE and infection; appropriate dosing of prophylactic anticoagulation and early removal of indwelling catheters may decrease these risks. Obesity is associated with improved critical illness survival in some studies. It is unclear whether this reflects a protective effect or limitations inherent to observational research. Obesity is associated with increased risk of intubation and death in SARS-CoV-2 infection. Ongoing molecular studies of adipose tissue may deepen our understanding of how obesity impacts critical illness pathophysiology.

Contraindications to the Initiation of Veno-Venous ECMO for Severe Acute Respiratory Failure in Adults: A Systematic Review and Practical Approach Based on the Current Literature

(1) Background: Extracorporeal membrane oxygenation (ECMO) is increasingly used for acute respiratory failure with few absolute but many relative contraindications. The provider in charge often has a difficult time weighing indications and contraindications to anticipate if the patient will benefit from this treatment, a decision that often decides life and death for the patient. To assist in this process in coming to a good evidence-based decision, we reviewed the available literature. (2) Methods: We performed a systematic review through a literature search of the MEDLINE database of former and current absolute and relative contraindications to the initiation of ECMO treatment. (3) Results: The following relative and absolute contraindications were identified in the literature: absolute-refusal of the use of extracorporeal techniques by the patient, advanced stage of cancer, fatal intracerebral hemorrhage/cerebral herniation/intractable intracranial hypertension, irreversible destruction of the lung parenchyma without the possibility of transplantation, and contraindications to lung transplantation; relative-advanced age, immunosuppressed patients/pharmacological immunosuppression, injurious ventilator settings > 7 days, right-heart failure, hematologic malignancies, especially bone marrow transplantation and graft-versus-host disease, SAPS II score ≥ 60 points, SOFA score > 12 points, PRESERVE score ≥ 5 points, RESP score ≤ -2 points, PRESET score ≥ 6 points, and "do not attempt resuscitation" order (DN(A)R status). (4) Conclusions: We provide a simple-to-follow algorithm that incorporates absolute and relative contraindications to the initiation of ECMO treatment. This algorithm attempts to weigh pros and cons regarding the benefit for an individual patient and hopefully assists caregivers to make better, informed decisions.

Obesity as a Risk Factor for Failure to Wean from ECMO: A Systematic Review and Meta-Analysis

Purpose

Obesity has been associated with an increased risk of respiratory complications and other systemic illnesses. Respiratory dynamics in an obese patient, combined with modified lung physiology of ARDS, present a significant challenge in managing obese patients with ARDS. Many physicians think of obesity as a relative contraindication to ECMO. We performed a meta-analysis to see the effect of obesity on weaning from ECMO and survival to hospital discharge.

Methods

We searched online databases for studies on ECMO and obesity. The search yielded 49 citations in total; after extensive review, six studies were assessed and qualified to be included in the final analysis. Patients were stratified into BMI >30 kg/m2 (obese) and BMI < 30 kg/m2 (nonobese).

Results

In meta-analysis, there was a total sample population of 1285 patients, with 466 in the obese group and 819 in the nonobese group. There was no significant difference in weaning from ECMO when compared between obese and nonobese patients, with a risk ratio of 1.03 and 95% confidence interval (CI) of 0.94-1.13 (heterogeneity: chi2 = 7.44, df = 4 (p=0.11), I 2 = 46%). There was no significant difference in survival rates between obese and nonobese patients who were treated with ECMO during hospitalization, with a risk ratio of 1.04 and 95% CI of 0.86-1.25 (heterogeneity: Tau2 0.03, chi2 = 14.61, df = 5 (p=0.01), I 2 = 66%).

Conclusion

Our findings show no significant difference in survival and weaning from ECMO in obese vs. nonobese patients. ECMO therapy should not be withheld from obese patients, as obesity is not a contraindication to ECMO.

Obesity is not a contraindication to veno-arterial extracorporeal life support

OBJECTIVES

Obesity may complicate the peripheral cannulation and delivery of veno-arterial extracorporeal life support (ECLS). With rising global body mass indices (BMI), obesity is becoming increasingly prevalent in severe cardiogenic shock yet its impact on outcomes is not well described. This study sought to examine the relationship between BMI and veno-arterial ECLS outcomes to better inform clinical decision-making.

METHODS

All cardiogenic shock patients undergoing peripheral veno-arterial ECLS at our institution from March 2008 to January 2019 were retrospectively analysed (n = 431). Patients were divided into 4 groups, BMI 17.5-24.9, 25-29.9, 30-34.9 and ≥35 kg/m2, and compared on clinical outcomes. Multivariable logistic regression was performed to identify variables associated with survival to discharge, the primary outcome of interest.

RESULTS

The median BMI was 28.3 kg/m2 (interquartile range 24.8-32.6) with a range of 17.0-69.1 kg/m2. Obese patients achieved significantly lower percentages of predicted flow rates compared with BMI < 25 kg/m2 patients though did not differ in their lactate clearances. Patients with BMI ≥35 kg/m2 had similar complication rates to the other cohorts but were more likely to require continuous veno-venous haemodialysis (51% vs 25-40% in other cohorts, P = 0.002). Overall survival to discharge was 48% (n = 207/431) with no differences between the cohorts (P = 0.92). Patients with BMI ≥35 kg/m2 had considerably lower survival (10%) in extracorporeal membrane oxygenation cardiopulmonary resuscitation compared with the other groups (P = 0.17). On multivariable logistic regression, BMI was not significantly associated with failure to survive to discharge.

CONCLUSIONS

In conclusion, with the rising global prevalence of obesity, the results of our study suggest that clinicians need not treat obesity as a negative prognostic factor in cardiogenic shock requiring ECLS.

First report about a successful ECLS implantation and subsequent helicopter transfer of a super obese patient with a BMI of 78 kg/m2

Our tertiary center provides 24/7 ECMO implantation and transport service nationwide. In 2018, 150 ECLS/ECMO were implanted, and 40 patients were transported on ECLS/ECMO. In this report, we describe a successful veno-arterial ECLS implantation in a super obese (BMI 78 kg/m²) 50-year-old female patient at a primary care hospital with subsequent helicopter transfer to our tertiary center.

Extracorporeal membrane oxygenation in patients with heart transplantation : A clinical prognosis analysis

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is indicated for bridging to heart transplantation, graft failure, and right heart failure after heart transplantation. This study explored risk factors affecting the clinical prognosis of cardiac transplantation patients treated with ECMO during the perioperative period.

METHODS

Data on 28 heart transplantation patients with ECMO obtained from January 2012 to January 2018 in the People's Hospital of Zhongshan City were retrospectively analyzed.

RESULTS

A total of 25 patients (20 male and 5 female) were finally included. Heart transplantation was performed mainly due to cardiomyopathy (77.8%). Of the treated patients, 18 (72%) survived and were discharged, 4 were treated with cardiopulmonary resuscitation (CPR) before ECMO, and 3 died in hospital. There were no differences between the surviving and death group donors (N-terminal pro b‑type natriuretic peptide [NT-proBNP], creatine kinase-muscle/brain [CK-MB], warm ischemia time of donated heart, cold ischemia time of donated heart, total ischemia time of donated heart, and donor type). In univariate analysis, body mass index (BMI), length of stay in the intensive care unit (ICU), and CPR were relevant prognostic factors for heart transplantation patients with ECMO. Multi-factor logistic regression showed that CPR before ECMO (odds ratio, OR, 49.45; 95% confidence interval, CI, [1.37, 1781.6]; P = 0.033) is an independent risk factor influencing prognosis.

CONCLUSION

ECMO is an important life support method for patients before and after heart transplantation surgery. Obesity, poor preoperative cardiac function, and considerable intraoperative red blood cell transfusion may influence prognosis. Extracardiac compression before ECMO is an independent risk factor for prognosis.

ARDS in Obese Patients: Specificities and Management

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2019. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2019. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

A decade of interfacility extracorporeal membrane oxygenation transport

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) is used to provide support for patients with cardiopulmonary failure. Best available medical management often fails in these patients and referring hospitals have no further recourse for escalating care apart from transfer to a tertiary facility. In severely unstable patients, the only option might be to use ECMO to facilitate safe transport. This study aimed to examine the characteristics and outcomes of patients transported while receiving ECMO.

METHODS

Statistical analysis was performed on data gathered retrospectively from the electronic medical records of adult patients transported while receiving ECMO to Columbia University Medical Center between January 1, 2008, and December 31, 2017.

RESULTS

Two hundred sixty five adult patients were safely transported while receiving ECMO with no transport-related complications that adversely affected outcomes. Transport distance ranged from 0.2 to 7084 miles with a median distance of 16.9 miles. One hundred eighty-three (69%) received on veno-venous, 72 (27%) veno-arterial, and 10 (3.8%) veno-venous arterial or veno-arterial venous configurations. Two hundred ten (79%) cannulations were performed at our institution at the referring hospital. Sixty-four percent of patients transported while receiving ECMO survived to hospital discharge.

CONCLUSIONS

Interfacility transport during ECMO was shown to be safe and effective with minimal complications and favorable outcomes when performed at an experienced referral center using stringently applied protocols.