The impact of obesity on the outcome of severe SARS-CoV-2 ARDS in a high volume ECMO centre: ECMO and corticosteroids support the obesity paradox

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

Obesity is increasing in prevalence worldwide and carries a theoretical increased risk of morbidity and mortality in critical illness, including hypercoagulability, thrombosis, and renal dysfunction. Obesity has historically been considered a relative contraindication to candidacy for extracorporeal membrane oxygenation (ECMO); however, recent research has suggested that obesity may be associated with improved outcomes in ECMO. This review was conducted to assess and synthesize the existing literature on ECMO outcomes in the obese population. We searched PubMed, Scopus, and CENTRAL databases for obesity and ECMO outcomes, and articles were screened independently by 2 authors. The selection process yielded 29 articles, with one ambispective and 28 retrospective cohort studies. Analyses of these studies show no evidence of globally increased mortality or complications in obesity. Prospective evaluation is needed to further investigate this relationship, but there is currently no evidence to support using body mass index as exclusionary criteria for ECMO.

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.

Extracorporeal Membrane Oxygenation for Septic Shock in Adults and Children: A Narrative Review

Refractory septic shock is associated with a high risk of death. Circulatory support in the form of veno-arterial extracorporeal membrane oxygenation (VA ECMO) may function as a bridge to recovery, allowing for the treatment of the source of the sepsis. Whilst VA ECMO has been accepted as the means of hemodynamic support for children, in adults, single center observational studies show survival rates of only 70-90% for hypodynamic septic shock. The use of VA ECMO for circulatory support in hyperdynamic septic shock with preserved cardiac output or when applied late during cardio-pulmonary resuscitation is not recommended. With unresolving septic shock and a loss of ventriculo-arterial coupling, stress cardiomyopathy often develops. If the cardiac index (CI) approaches subnormal levels (CI < 2.5 L/min m-2) that do not match low systemic vascular resistance with a resulting loss of vital systemic perfusion pressure, VA ECMO support should be considered. A further decrease to the level of cardiogenic shock (CI < 1.8 L/min m-2) should be regarded as an indication for VA ECMO insertion. For patients who maintain a normal-to-high CI as part of their refractory vasoparalysis, VA ECMO support is justified in children and possibly in patients with a low body mass index. Extracorporeal support for septic shock should be limited to high-volume ECMO centers.

Prognostic Impact of Serial Imaging in Severe Acute Respiratory Distress Syndrome on the Extracorporeal Membrane Oxygenation

BACKGROUND

The impact of serial imaging on the outcome of ICU patients has not been studied specifically in patients with high illness severity.

METHODS

The authors sought a relationship between the numbers of antero-posterior supine chest X-rays (CXR), computed tomography (CT) examinations, and outcome in a cohort of 292 patients with severe COVID-19 ARDS collected over 24 months in a high-volume ECMO center with established ultrasound and echocardiographic diagnostics. Of the patients, 172 (59%) were obese or morbidly obese, and 119 (41%) were treated with ECMO.

RESULTS

The median number of CXRs was eight per 14 days of the length of stay in the ICU. The CXR rate was not related to ICU survival (p = 0.37). Patients required CT scanning in 26.5% of cases, with no relationship to the outcome except for the better ICU survival of the ECMO patients without a need for a CT scan (p = 0.01). The odds ratio for survival associated with ordering a CT scan in an ECMO patient was 0.48, p = 0.01. The calculated savings for not routinely requesting a whole-body CT scan in every patient were 98.685 EUR/24 months.

CONCLUSIONS

Serial imaging does not impact the survival rates of patients with severe ARDS. Extracorporeal membrane oxygenation patients who did not need CT scanning had significantly better ICU outcomes.

Mortality in Patients with Obesity and Acute Respiratory Distress Syndrome Receiving Extracorporeal Membrane Oxygenation: The Multicenter ECMObesity Study

Rationale: Patients with obesity are at increased risk for developing acute respiratory distress syndrome (ARDS). Some centers consider obesity a relative contraindication to receiving extracorporeal membrane oxygenation (ECMO) support, despite growing implementation of ECMO for ARDS in the general population. Objectives: To investigate the association between obesity and mortality in patients with ARDS receiving ECMO. Methods: In this large, international, multicenter, retrospective cohort study, we evaluated the association of obesity, defined as body mass index ⩾ 30 kg/m2, with ICU mortality in patients receiving ECMO for ARDS by performing adjusted multivariable logistic regression and propensity score matching. Measurements and Main Results: Of 790 patients with ARDS receiving ECMO in our study, 320 had obesity. Of those, 24.1% died in the ICU, compared with 35.3% of patients without obesity (P < 0.001). In adjusted models, obesity was associated with lower ICU mortality (odds ratio, 0.63 [95% confidence interval, 0.43-0.93]; P = 0.018). Examined as a continuous variable, higher body mass index was associated with decreased ICU mortality in multivariable regression (odds ratio, 0.97 [95% confidence interval, 0.95-1.00]; P = 0.023). In propensity score matching of 199 patients with obesity to 199 patients without, patients with obesity had a lower probability of ICU death than those without (22.6% vs. 35.2%; P = 0.007). Conclusions: Among patients receiving ECMO for ARDS, those with obesity had lower ICU mortality than patients without obesity in multivariable and propensity score matching analyses. Our findings support the notion that obesity should not be considered a general contraindication to ECMO.

Long-Term Outcomes of Extracorporeal Life Support in Respiratory Failure

Although extracorporeal life support is an expensive method with serious risks of complications, it is nowadays a well-established and generally accepted method of organ support. In patients with severe respiratory failure, when conventional mechanical ventilation cannot ensure adequate blood gas exchange, veno-venous extracorporeal membrane oxygenation (ECMO) is the method of choice. An improvement in oxygenation or normalization of acid-base balance by itself does not necessarily mean an improvement in the outcome but allows us to prevent potential negative effects of mechanical ventilation, which can be considered a crucial part of complex care leading potentially to an improvement in the outcome. The disconnection from ECMO or discharge from the intensive care unit should not be viewed as the main goal, and the long-term outcome of the ECMO-surviving patients should also be considered. Approximately three-quarters of patients survive the veno-venous ECMO, but various (both physical and psychological) health problems may persist. Despite these, a large proportion of these patients are eventually able to return to everyday life with relatively little limitation of respiratory function. In this review, we summarize the available knowledge on long-term mortality and quality of life of ECMO patients with respiratory failure.

Obesity Paradox in Lung Diseases: What Explains It?

BACKGROUND

Obesity is a globally increasing health problem that impacts multiple organ systems and a potentially modifiable risk factor for many diseases. Obesity has a significant impact on lung function and is strongly linked to the pathophysiology that contributes to lung diseases. On the other hand, reports have emerged that obesity is associated with a better prognosis than for normal weight individuals in some lung diseases, including pneumonia, acute lung injury/acute respiratory distress syndrome, chronic obstructive pulmonary disease, and lung cancer. The lesser mortality and better prognosis in patients with obesity is known as obesity paradox. While obesity paradox is both recognized and disputed in epidemiological studies, recent research has suggested possible mechanisms.

SUMMARY

In this review, we attempted to explain and summarize these factors and mechanisms, including immune response, pulmonary fibrosis, lung function, microbiota, fat and muscle reserves, which are significantly altered by obesity and may contribute to the obesity paradox in lung diseases. We also discuss contrary literature that attributes the "obesity paradox" to confounding.

KEY MESSAGES

The review will illustrate the possible role of obesity in the prognosis or course of lung diseases, leading to a better understanding of the obesity paradox and provide hints for further basic and clinical research in lung diseases.

The Importance of COVID-19/Influenza Vaccines Co-Administration: An Essential Public Health Tool

Vaccine co-administration is an important tool with several advantages for public health, among which is the increase of vaccination coverage, as well as economic and logistical benefits. The purpose of this study was to assess and compare the immune response to the COVID-19 first booster dose in healthcare workers (HCWs) who chose co-administration and in HCWs who received only COVID-19 vaccination and to investigate personal opinions about the experience of co-administration. We carried out a retrospective analysis involving two groups of HCWs, both vaccinated with the complete primary cycle and the first booster dose of the COVID-19 vaccine, but one of them was also vaccinated, at the same time as the first booster dose, with the influenza vaccine. Active phone calls were also performed, and specific questions about the onset of side effects and general opinions were asked. A good immune response was found in both two groups without any statistically significant difference in the immune response. No severe reactions occurred in either group. A greater part of the sample was completely satisfied, and they would do it again. Our findings are totally in favor of the co-administration, considering the many positive aspects provided by administering, at the same time, more vaccines.

Role of the 1st booster dose of COVID-19 vaccine in the protection against the infection: A fundamental public health tool

Introduction

The COVID-19 pandemic is having a huge impact on human health with high morbidity and mortality rates worldwide. Healthcare Workers (HCWs) are one of the most at risk categories to contract the infection. Effective anti-COVID-19 vaccines were approved in a very short time. Making the 1^st booster dose is essential to induce a good protection against the infection.

Methods

We conducted a retrospective sero-epidemiological survey of already existing data concerning the antibody response of a HCWs sample vaccinated with the primary cycle and the 1^st booster dose of the Pfizer-BioNTech COVID-19 mRNA vaccine and, specifically, after three weeks from the third dose of vaccination.

Results

In our analysis, after the primary cycle, a 95.15% efficacy was detected. Among the non-responders, women were significantly more frequent (69.56%). Moreover, we found a significant reverse correlation between the immune response and the age of the sample, especially in women. However, the 1^st booster dose completely cancelled these differences.

Conclusions

Our data are perfectly in line with what has been declared by the conducted studies in terms of efficacy. However, it is important to highlight that people with only the primary cycle are at high risk to contract the COVID-19 infection. Therefore, it is necessary to not consider people vaccinated with the primary cycle completely risk-free and to stress the importance to perform the 1^st booster dose.