Risk factors for short-term mortality from carbon monoxide poisoning treated with hyperbaric oxygen*

Abstract

Carbon monoxide (CO) poisoning is common in the United States, accounting for approximately 2,700 deaths annually. Few publications have described the mortality rate of CO-poisoned patients who survive to reach a hospital and die despite maximal medical care. Further, while risk factors for cognitive sequelae in survivors of CO poisoning have become clearer recently, factors associated with death are less well defined. This study was conducted to 1) determine the short-term mortality risk for patients treated with hyperbaric oxygen for CO poisoning, and 2) determine whether any factors related to the poisoning episode are predictive of mortality. A departmental database and medical records of 1,505 consecutive patients treated with hyperbaric oxygen at a single institution from 1978 to 2005 were reviewed. Demographic and clinical data were extracted for analysis. Mortality data, including cause of death, were obtained through a search of the National Death Index of the National Center for Health Statistics. A total of 38 patients experienced short-term mortality from their episode of CO poisoning, yielding a death rate of 2.6% in medically treated patients. Characteristics significantly associated with mortality included fire as a source of CO, loss of consciousness, carboxyhemoglobin level, arterial pH, and presence of endotracheal intubation during hyperbaric treatment. The mortality rate for medically treated CO-poisoned patients in this series was 2.6%, similar to the limited combined experience previously reported in the literature. Factors most strongly associated with mortality were severe metabolic acidosis and need for endotracheal intubation.