Clinically Relevant Blood Pressure Elevation During Apnea Testing for Brain Death Determination: Association With Circulating Catecholamines.

Abstract

Objective: To characterize hemodynamic changes during apnea testing for brain death determination and evaluate their clinical relevance while exploring associations with circulating catecholamines.

Methods: We retrospectively analyzed 27 patients who underwent apnea testing between January 2020 and March 2024. Each patient underwent two apnea tests, during which heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured at baseline and within 1-7 minutes after testing. Peak post-test values were compared with baseline values. Plasma catecholamines were measured before and after the first test in a subset of 13 patients.

Results: Both apnea tests were associated with significant increases in cardiovascular parameters. Median SBP increased from 123.5 mmHg (interquartile range [IQR], 109.2 to 142.0) to 147.5 mmHg (IQR, 128.0 to 178.8; p<0.001). Median HR increased from 81.0 beats/min (IQR, 72.0 to 96.0) to 90.0 beats/min (IQR, 75.2 to 102.2), and DBP increased from 70.0 mmHg (IQR, 62.0 to 81.0) to 82.5 mmHg (IQR, 70.5 to 99.0) (all p<0.001). Post-test SBP exceeded 140 mmHg and 160 mmHg in 61.1% and 38.9% of tests, respectively. Peak mean arterial pressure increased to 105.5 mmHg (IQR, 89.3 to 125.7), exceeding 90 mmHg and 100 mmHg in 72.2% and 57.4% of tests, respectively. In subset analysis, epinephrine increased modestly, whereas norepinephrine and dopamine remained unchanged.

Conclusion: Apnea testing consistently induced clinically relevant increases in blood pressure and HR without corresponding elevations in circulating catecholamines, suggesting additional mechanisms may contribute to these hemodynamic responses during apnea testing.