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.

Outcomes in Obese Adult Veno-Venous Extracorporeal Membrane Oxygenation: A Systematic Review

Obesity is associated with an overall increased risk of morbidity and mortality. However, in patients with critical illness, sepsis, and acute respiratory distress syndrome, obesity may be protective, termed "the obesity paradox." This is a systematic literature review of articles published from 2000 to 2022 evaluating complications and mortality in adults with respiratory failure on veno-venous extracorporeal membrane oxygenation (VV ECMO) based on body mass index (BMI). Eighteen studies with 517 patients were included. Common complications included acute renal failure (175/377, 46.4%), venous thrombosis (175/293, 59.7%), and bleeding (28/293, 9.6%). Of the six cohort studies, two showed improved mortality among obese patients, two showed a trend toward improved mortality, and two showed no difference. Comparing all patients in the studies with BMI of less than 30 to those with BMI of greater than or equal to 30, we noted decreased mortality with obesity (92, 37.1% of BMI <30 vs. 30, 11% of BMI ≥30, p ≤ 0.0001). Obesity may be protective against mortality in adult patients undergoing VV ECMO. Morbid and super morbid obesity should not be considered a contraindication to cannulation, with patients with BMI ≥ 80 surviving to discharge. Complications may be high, however, with higher rates of continuous renal replacement therapy and thrombosis among obese patients.

Comparison of Sedation and Analgesia Requirements in Patients With SARS-CoV-2 Versus Non-SARS-CoV-2 Acute Respiratory Distress Syndrome on Veno-Venous ECMO

BACKGROUND

Increased analgosedation requirements have been described in patients with acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation (ECMO) support due to unique pharmacokinetic challenges. There is a paucity of data comparing sedation requirements in patients on ECMO for ARDS secondary to SARS-CoV-2 versus other etiologies of respiratory failure.

OBJECTIVE

To compare sedation and analgesia requirements in adult patients with SARS-CoV-2 versus non-SARS-CoV-2 ARDS requiring veno-venous (VV) ECMO support.

METHODS

We performed a retrospective cohort study of adult patients receiving sedation and analgesia on VV-ECMO support. Patients were excluded if cannulated at an outside hospital for greater than 24 hours, expired within 48 hours of ECMO cannulation, or received neuromuscular blocking agents for greater than 7 consecutive days following ECMO cannulation.

RESULTS

We evaluated 108 patients on VV-ECMO support, including 44 with non-SARS-CoV-2 ARDS and 64 with SARS-CoV-2 ARDS. The median daily dexmedetomidine requirements were significantly higher in the SARS-CoV-2 cohort (16.7 vs 13.4 mcg/kg/day, P = 0.03), while the median propofol daily requirements were significantly higher in the non-SARS-CoV-2 cohort (40.3 vs 53.5 mg/kg/day, P < 0.01). There was no difference in daily requirements of opioids, benzodiazepines, and ketamine between groups. Use of adjunct agents to facilitate weaning was significantly higher in the SARS-CoV-2 cohort (78.1% vs 43.2%, P < 0.01).

CONCLUSION AND RELEVANCE

Patients with ARDS on VV-ECMO support require multiple analgosedative agents with concomitant use of nonparenteral adjunct agents. Further studies are needed to evaluate optimal analgosedation strategies in patients on ECMO support.

Impact of BMI on outcomes in respiratory ECMO: an ELSO registry study

PURPOSE

The impact of body mass index (BMI) on outcomes in respiratory failure necessitating extracorporeal membrane oxygenation (ECMO) has been poorly described. We aimed to assess: (i) whether adults with class II obesity or more (BMI ≥ 35 kg/m²) have worse outcomes than lean counterparts, (ii) the form of the relationship between BMI and outcomes, (iii) whether a cutoff marking futility can be identified.

METHODS

A retrospective analysis of the Extracorporeal Life Support Organization (ELSO) Registry from 1/1/2010 to 31/12/2020 was conducted. Impact of BMI ≥ 35 kg/m² was assessed with propensity-score (PS) matching, inverse propensity-score weighted (IPSW) and multivariable models (MV), adjusting for a priori identified confounders. Primary outcome was in-hospital mortality. The form of the relationship between BMI and outcomes was studied with generalized additive models. Outcomes across World Health Organisation (WHO)-defined BMI categories were compared.

RESULTS

Among 18,529 patients, BMI ≥ 35 kg/m² was consistently associated with reduced in-hospital mortality [PS-matched: OR: 0.878(95%CI 0.798-0.966), p = 0.008; IPSW: OR: 0.899(95%CI 0.827-0.979), p = 0.014; MV: OR: 0.900(95%CI 0.834-0.971), p = 0.007] and shorter hospital length of stays. In patients with BMI ≥ 35 kg/m², cardiovascular (17.3% versus 15.3%), renal (37% versus 30%) and device-related complications (25.7% versus 20.6%) increased, whereas pulmonary complications decreased (7.6% versus 9.3%). These findings were independent of confounders throughout PS-matched, IPSW and MV models. The relationship between BMI and outcomes was non-linear and no cutoff for futility was identified.

CONCLUSION

Patients with obesity class II or more treated with ECMO for respiratory failure have lower mortality risk and shorter stays, despite increased cardiovascular, device-related, and renal complications. No upper limit of BMI indicating futility of ECMO treatment could be identified. BMI as single parameter should not be a contra-indication for respiratory ECMO.

Analgosedation in Critically Ill Adults Receiving Extracorporeal Membrane Oxygenation Support

Extracorporeal membrane oxygenation (ECMO) is an increasingly utilized intervention for cardiopulmonary failure. Analgosedation during ECMO support is essential to ensure adequate pain and agitation control and ventilator synchrony, optimize ECMO support, facilitate patient assessment, and minimize adverse events. Although the principles of analgosedation are likely similar for all critically ill patients, ECMO circuitry alters medication pharmacodynamics and pharmacokinetics. The lack of clinical guidelines for analgosedation during ECMO, especially at times of medication shortage, can affect patient management. Here, we review pharmacological considerations, protocols, and special considerations for analgosedation in critically ill adults receiving ECMO support.

A Narrative Review of the Impact of Extracorporeal Membrane Oxygenation on the Pharmacokinetics and Pharmacodynamics of Critical Care Therapies

Objective:

Extracorporeal membrane oxygenation (ECMO) utilization is increasing on a global scale, and despite technological advances, minimal standardized approaches to pharmacotherapeutic management exist. This objective was to create a comprehensive review for medication dosing in ECMO based on the most current evidence.

Data Sources:

A literature search of PubMed was performed for all pertinent articles prior to 2022. The following search terms were utilized: ECMO, pharmacokinetics, pharmacodynamics, sedation, analgesia, antiepileptic, anticoagulation, antimicrobial, antifungal, nutrition. Retrospective cohort studies, case-control studies, case series, case reports, and ex vivo investigations were reviewed.

Study Selection and Data Extraction:

PubMed (1975 through July 2022) was the database used in the literature search. Non-English studies were excluded. Search terms included both drug class categories, specific drug names, ECMO, and pharmacokinetics.

Data Synthesis:

Medications with high protein binding (>70%) and high lipophilicity (logP > 2) are associated with circuit sequestration and the potential need for dose adjustment. Volume of distribution changes with ECMO may also impact dosing requirements of common critical care medications. Lighter sedation targets and analgosedation may help reduce sedative and analgesia requirements, whereas higher antiepileptic dosing is recommended. Vancomycin is minimally affected by the ECMO circuit and recommendations for dosing in critically ill adults are reasonable. Anticoagulation remains challenging as optimal aPTT goals have not been established.

Relevance to Patient Care and Clinical Practice:

This review describes the anticipated impacts of ECMO circuitry on sedatives, analgesics, anticoagulation, antiepileptics, antimicrobials, antifungals, and nutrition support and provides recommendations for drug therapy management.

Conclusions:

Medication pharmacokinetic/pharmacodynamic parameters should be considered when determining the potential impact of the ECMO circuit on attainment of therapeutic effect and target serum drug concentrations, and should guide therapy choices and/or dose adjustments when data are not available.

Impact of CytoSorb Hemoadsorption on Sedation Requirements in Patients With Severe COVID-19 on Venovenous Extracorporeal Membrane Oxygenation

Hemoadsorption with CytoSorb has been used as an adjunct in the treatment of severe coronavirus disease 2019 (COVID-19)-related respiratory failure. It remains unknown if CytoSorb hemoadsorption will alter sedative and analgesic dosing in critically ill patients on venovenous extracorporeal membrane oxygenation (VV-ECMO). We conducted a retrospective review of patients with severe COVID-19 requiring VV-ECMO for respiratory support. Patients who were enrolled in a clinical study of CytoSorb were compared with patients on VV-ECMO alone. Data were collected for the 72-hour CytoSorb therapy and an additional 72 hours post-CytoSorb, or a corresponding control time period. Sedative and analgesic doses were totaled for each day and converted to midazolam or fentanyl equivalents, respectively. The primary endpoint, change in sedative and analgesic requirements over time, were compared using a two-way mixed analysis of variance. Of the 30 patients cannulated for VV-ECMO for COVID-19, 4 were excluded, leaving 8 patients in the CytoSorb arm and 18 in the Control. There was no effect of CytoSorb therapy on midazolam equivalents over the 72-hour therapy (p = 0.71) or the 72 hours post-CytoSorb (p = 0.11). In contrast, there was a significant effect of CytoSorb therapy on fentanyl equivalents over the first 72 hours (p = 0.01), but this was not consistent over the 72-hours post-CytoSorb (p = 0.23). CytoSorb therapy led to significant increases in analgesic requirements without impacting sedative requirements. Further research is needed to define the relevance of CytoSorb hemoadsorption on critical care pharmacotherapy.

Approach to Sedation and Analgesia in COVID-19 Patients on Venovenous Extracorporeal Membrane Oxygenation

OBJECTIVE

To describe clinically pertinent challenges of managing sedation in COVID-19 patients on venovenous extracorporeal membrane oxygenation (VV-ECMO) and describe considerations for enhanced safety and efficacy of pharmacological agents used.

DATA SOURCES

A PubMed search was performed using the following search terms: ECMO, ARDS, sedation, COVID-19, coronavirus, opioids, analgesia, fentanyl, hydromorphone, morphine, oxycodone, methadone, ketamine, propofol, dexmedetomidine, clonidine, benzodiazepines, midazolam, lorazepam, and diazepam.

STUDY SELECTION AND DATA EXTRACTION

Relevant clinical and pharmacokinetic studies were considered. All studies included were published between January 1988 and March 2021.

DATA SYNTHESIS

Patients with acute respiratory distress syndrome secondary to COVID-19 may progress to requiring VV-ECMO support. Agents frequently used for sedation and analgesia in these patients have been shown to have significant adsorption to ECMO circuitry, leading to possible diminished clinical efficacy. Use of hydromorphone-based analgesia has been associated with improved clinical outcomes in patients on VV-ECMO. However, safety and efficacy regarding use of other agents in this patient population remains an area of further research.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review addresses clinical challenges associated with sedation management in COVID-19 patients requiring VV-ECMO support and provides potential strategies to overcome these challenges.

CONCLUSIONS

Historically, sedation and analgesia management in patients requiring ECMO support have posed a challenge for bedside clinicians given the unique physiological and pharmacokinetic changes in this patient population. A multimodal strategy to managing analgesia and sedation should be used, and the use of enteral agents may play a role in reducing parenteral agent requirements.

TIVA for ECMO and VAD

In recent decades, the use of temporary and permanent use of mechanical assist devices is on the rise for patients with end-stage cardiac failure. These support strategies hold inherently different risks in the face of noncardiac critical illness and require multidisciplinary treatment strategies. The main issues with all mechanical devices whether extracorporeal membrane oxygenation (ECMO) or ventricular assist device (VAD), are related to thrombosis, anticoagulation, infection, avoiding hypertension and thus use of intravenous drugs, which requires intense monitoring, to circumvent further renal, ischemic or neurological injury and prevent complication.