Consent for the Apnea Test: Asking the Wrong Question*

Abstract

I n this issue of Pediatric Critical Care Medicine, Sveen et al (1) wrote that "some parents and providers have asserted informed consent is required for [the apnea test] AT due to the risk of serious adverse events" and concluded that their study's "findings may inform the ongoing debate regarding whether specific informed consent should be required for AT. " They based this on their empirical findings of adverse event rates that occurred during the apnea test (AT), and the "general consent for medical treatment" upon admission to the hospital (1).The authors report a retrospective study of all 105 ATs done in 58 patients at Cincinnati Children's Hospital Medical Center from July 2013 to June 2020. Adverse events during the AT were defined as hypotension (mean arterial pressure < 5th percentile for age), hypoxia (pulse oximetry saturation < 85%), new or increased pneumothorax, arrhythmia, new intracranial hypertension (intracranial pressure [ICP] > 20 mm Hg), or cardiac arrest. No patients had arrhythmia, new intracranial hypertension (because all had this prior to the AT), or cardiac arrest. Adverse events (hypotension, hypoxia, and/or pneumothorax) occurred in 21 of 105 AT (20%), and led to premature termination of the AT in five of 105 (5%), with the rest "managed medically… with transient increase in vasoactive support, or with completion of the AT" (1). The "transient" increases in vasoactive support lasted "less than 1 hour" (1). The six or seven patients monitored had 15 AT with no change in ICP from pre-AT (median, 72 mm Hg; interquartile range [IQR], 61-82 mm Hg) to post-AT (median, 72 mm Hg; IQR, 60-83 mm Hg). One patient had absent breathing on the second AT but spontaneous breathing on the third AT. There were no "vital sign changes consistent with herniation" identified, although presumably, most patients had brain herniation as part of the usual pathophysiology of brain death (BD) (1).Limitations of the study discussed by the authors included that the study was single center and retrospective, that it was possible AT was deferred in some patients felt to be at high risk of decompensation, and that the few patients with ICP monitoring had severe intracranial hypertension at baseline "preventing any assessment regarding potential AT effects on cerebral perfusion" (1). In these patients, the cerebral perfusion pressure (CPP) was likely already above the critical closing pressure of cerebral vessels pre-AT. There was a lack of arterial access during 20 AT, making accurate assessment of transient hypotension in those patients impossible. Nevertheless, given that adverse events occurred in only 20% of AT and "resolved with medical care" or premature termination of the AT "without further intervention, " the findings "may inform the ongoing debate regarding whether specific consent should be required for AT" (1). *See also p. 399.

Writing for Pediatric Critical Care Medicine: Editorials and Commentaries

“…The authors focused on the overall adverse event rate of 20%, with premature termination of the apnea test in 5%; there was no analysis of consent for such testing, but it was mentioned in the discussion. The accompanying editorial served as a literary vehicle for examining problems with the apnea test (15). It also focused on the issue of consent and made readers think about whether we were "asking the wrong question"; that is, why is there an apnea test in the protocol for determination of death using neurologic criteria?…”