American journal of therapeutics
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Endogenous carbon monoxide (CO) is produced in the degradation of heme by heme oxygenase. Studies have shown that hypoxia induces heme oxygenase production of CO in vascular tissue. Because elevated plasma lactate levels are associated with tissue hypoxia, we determined if there was any correlation between lactate and carboxyhemoglobin (COHb) levels in a group of critically ill patients with a high likelihood of hypoxia. ⋯ Levels of endogenous CO do not increase in situations in which lactate production is increased. It is possible that changes in endogenous production of CO may not significantly affect the circulating level of COHb. Although readily available, COHb levels do not seem to be clinically useful as markers of critical illness.