Unexpected carboxyhemoglobin half-life during cardiopulmonary resuscitation: a case report

Cardiac arrest (CA) following CO poisoning (CO-induced CA) exposes patients to an extremely high risk of mortality and remains challenging to treat effectively. Terminal carboxyhemoglobin elimination half-life (COHbt_1/2) is critically affected by ventilation, oxygen therapy, and cardiac output, which are severely affected conditions in cases of CA.

Asystole occurred in an 18-year-old woman after unintentional exposure to CO in her bathroom. Cardiopulmonary resuscitation (CPR) was started immediately, including mechanical ventilation with a fraction of inspired oxygen (FiO₂) of 1.0 and external chest compressions with a LUCAS® device. CPR was stopped after 101 min, as it was unsuccessful. During this period, we calculated a COHbt_1/2 of 40.3 min using a single compartmental model.

This result suggests that prolongation of CPR time needed to back COHb at 10%, a level more compatible with successful return of spontaneous circulation (ROSC), could be compatible with a realistic CPR time. Calculating COHbt_1/2 during CPR may help with decision-making regarding the optimal duration of resuscitation efforts and further with HBO₂ or ECLS. Further evidence-based data are needed to confirm this result.