Elevated carboxyhemoglobin in mechanically ventilated patients

M. Sedlacek, A. Klapholz

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Purpose: To determine the circumstances in which increased endogenous carbon monoxide (CO) production can be observed in patients protected from environmental sources of CO by being hospitalized and mechanically ventilated. Setting: inner city teaching hospital Materials and Methods: Carboxyhemoglobin (COHb) levels were determined by spectrophotometry with CO OX 2500 (Corning) whenever the total Hb concentration of a blood gas specimen was measured routinely. The mean value and standard deviation was calculated for all 2137 COHb levels that were documented from 07/01/95 to 11/30/95 as x=2.5% SD=1.0. A list of patients who had a COHb value>3.5 was compared with a list of all 154 patients that were intubated during that period and the resulting charts were reviewed. Elevated COHb levels on admission or from smokers were not considered. Results: In sixteen patients elevated COHb levels ranging from 3.7% to 5.2% were documented while being protected from environmental sources of CO. All patients were deteriorating clinically when the highest COHb was measured. All sixteen patients were in respiratory failure, thirteen of whom required mechanical ventilation. Three patients were not reintubated. All patients had SIRS by ACCP consensus definition criteria and in six patients sepsis was confirmed by blood cultures. Twelve out of the sixteen patients died during their hospitalization. Conclusion: We observed increased COHb levels up to 5.2% at the time of clinical deterioration with respiratory failure and SIRS associated with sepsis and death. Clinical Implications: Endogenous CO is produced by heme oxygenase which catabolises heme to biliverdin, free iron and CO. We provide some circumstantial evidence of a possible role of heme oxygenase in the pathophysiology of SIRS and sepsis. COHb is a readily available measurement and may have prognostic and therapeutic implications in the treatment of the critically ill.

Original languageEnglish
Pages (from-to)153S
Issue number4 SUPPL.
StatePublished - Oct 1996
Externally publishedYes


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