Carboxyhemoglobin levels as a predictor of mortality in acute respiratory failure

The purpose of this study was to determine if endogenous levels of carboxyh emoglobin (COHb) are elevated in patients intubated for respiratory failure , and, if so, whether these levels are predictive of in-hospital mortality, as was suggested previously An arterial blood gas was drawn within 24 hour s of admission and no sooner than 6 hours after intubation, in patients adm itted to our respiratory intensive care unit (RICU) or medical intensive ca re unit (MICU) for respiratory failure. An IL682 cooximeter was used to mea sure COHb levels. Apache II severity scoring was completed upon admission t o the hospital. Patients were then followed prospectively until either end point of death or extubation and discharge were reached. Both smokers and n onsmokers were included in the study: Of the 13 patients in the study, ther e were 4 survivors to extubation and discharge home and 9 deaths. None of t he patients had elevated COHb levels. The avenge level of COHb was less in the nonsurvivors (1.29%) than in the survivors (1.85%,NS). A statistically significant correlation was not noted between COHb level and either Apache II score or outcome. Apache II levels correlated well with outcome. There w as a 100% mortality rate in all patients with scores greater than or equal to 15. In patients intubated for respiratory failure and protected from env ironmental sources of CO, endogenous production of CO is not elevated. COHb levels therefore have no prognostic value in patients with RF.