Carbon dioxide narcosis - induced apnea in a rat model of cardiac arrest and resuscitation

In the clinical literature there are reports of patients failing to breathe and becoming comatose when supplied with 100% oxygen for respiratory distr ess. This effect has been attributed to a loss of respiratory drive. Recent studies have established that this explanation is incorrect, but have left the phenomenon unexplained. We propose that the apnea and coma reported is due to carbon dioxide narcosis. We have reproduced this effect in an anima l model and have documented PCO2 values in excess of 250 mmHg during the ap neic period. Our results suggest that this level of PCO2 suppresses both br ainstem auditory evoked potentials and spontaneous respiration. The high PC O2 is due to inadequate gas exchange, and is easily remedied by provision o f adequate ventilation. (C) 1998 Elsevier Science Ireland Ltd. All rights r eserved.