Prediction of Apnea Testing Duration to Ensure Safety During Brain Death Assessment

Abstract

BACKGROUND:

Apnea testing is the last step of brain death assessment. This study aimed to determine whether apnea testing is safer when performed over a shorter duration.

METHODS:

The medical records of 200 brain-dead donors were retrospectively evaluated. All the records were anonymously registered in the Japanese Ministry of Health, Labor, and Welfare from 1999 to 2012. The rate of ${\mathbf{\text{P}}}_{{\mathbf{\text{aCO}}}_{\mathbf{\text{2}}}}$ increase was analyzed to calculate the duration required for apnea testing.

RESULTS:

At baseline, body temperature and ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ significantly affected the increase rate of ${\mathbf{\text{P}}}_{{\mathbf{\text{aCO}}}_{\mathbf{\text{2}}}}$ . At baseline, the apnea testing durations were 4.7 min with normal body temperature and higher ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ ( ${\mathbf{\text{P}}}_{{\mathbf{\text{aCO}}}_{\mathbf{\text{2}}}}$ 40–60 mm Hg, body temperature 36.5°C, ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ 400 mm Hg); further, it was 3.0 min with higher body temperature and lower ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ at baseline ( ${\mathbf{\text{P}}}_{{\mathbf{\text{aCO}}}_{\mathbf{\text{2}}}}$ 40–60 mm Hg, body temperature 38.0°C, ${\mathbf{\text{P}}}_{{\mathbf{\text{aO}}}_{\mathbf{\text{2}}}}$ 100 mm Hg).

CONCLUSIONS:

The specific duration of apnea testing during brain death assessment may be predicted by measuring the increase rate of ${\mathbf{\text{P}}}_{{\mathbf{\text{aCO}}}_{\mathbf{\text{2}}}}$ .