Extracorporeal Membrane Oxygenation for Cardiac Arrest: Does Age Matter?

OBJECTIVES: The impact of age on hospital survival for patients treated with extracorporeal cardiopulmonary resuscitation (ECPR) for cardiac arrest (CA) is unknown. We sought to characterize the association between older age and hospital survival after ECPR, using a large international database. DESIGN: Retrospective analysis of the Extracorporeal Life Support Organization registry. PATIENTS: Patients 18 years old or older who underwent ECPR for CA between December 1, 2016, and October 31, 2020. MEASUREMENTS AND MAIN RESULTS: The primary outcome was adjusted odds ratio (aOR) of death after ECPR, analyzed by age group (18-49, 50-64, 65-74, and > 75 yr). A total of 5,120 patients met inclusion criteria. The median age was 57 years (interquartile range, 46-66 yr). There was a significantly lower aOR of survival for those 65-74 (0.68l 95% CI, 0.57-0.81) or those greater than 75 (0.54; 95% CI, 0.41-0.69), compared with 18-49. Patients 50-64 had a significantly higher aOR of survival compared with those 65-74 and greater than 75; however, there was no difference in survival between the two youngest groups (aOR, 0.91; 95% CI, 0.79-1.05). A sensitivity analysis using alternative age categories (18-64, 65-69, 70-74, and ≥ 75) demonstrated decreased odds of survival for age greater than or equal to 65 compared with patients younger than 65 (for age 65-69: odds ratio [OR], 0.71; 95% CI, 0.59-0.86; for age 70-74: OR, 0.84; 95% CI, 0.67-1.04; and for age ≥ 75: OR, 0.64; 95% CI, 0.50-0.81). CONCLUSIONS: This investigation represents the largest analysis of the relationship of older age on ECPR outcomes. We found that the odds of hospital survival for patients with CA treated with ECPR diminishes with increasing age, with significantly decreased odds of survival after age 65, despite controlling for illness severity and comorbidities. However, findings from this observational data have significant limitations and further studies are needed to evaluate these findings prospectively.

On the Transition from Control Modes to Spontaneous Modes during ECMO.

The transition from control modes to spontaneous modes is ubiquitous for mechanically ventilated patients yet there is little data describing the changes and patterns that occur to breathing during this transition for patients on ECMO. We identified high fidelity data among a diverse cohort of 419 mechanically ventilated patients on ECMO. We examined every ventilator change, describing the differences in >30,000 sets of original ventilator observations, focused around the time of transition from control modes to spontaneous modes. We performed multivariate regression with mixed effects, clustered by patient, to examine changes in ventilator characteristics within patients, including a subset among patients with low compliance (<30 milliliters (mL)/centimeters water (cmH2O)). We found that during the transition to spontaneous modes among patients with low compliance, patients exhibited greater tidal volumes (471 mL (364,585) vs. 425 mL (320,527); p < 0.0001), higher respiratory rate (23 breaths per minute (bpm) (18,28) vs. 18 bpm (14,23); p = 0.003), greater mechanical power (elastic component) (0.08 mL/(cmH2O × minute) (0.05,0.12) vs. 0.05 mL/(cmH2O × minute) (0.02,0.09); p < 0.0001) (range 0 to 1.4), and lower positive end expiratory pressure (PEEP) (6 cmH2O (5,8) vs. 10 cmH2O (8,11); p < 0.0001). For patients on control modes, the combination of increased tidal volume and increased respiratory rate was temporally associated with significantly low partial pressure of arterial oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio (p < 0.0001). These changes in ventilator parameters warrant prospective study, as they may be associated with worsened lung injury.