Pulse oximetry in severe carbon monoxide poisoning.
OBJECTIVE
To evaluate the accuracy and quantitate the error of pulse oximetry measurements of arterial oxygenation in patients with severe carbon monoxide (CO) poisoning.


METHODS
Retrospective review of patient clinical records.


METHODS
Regional referral center for hyperbaric oxygen therapy.


METHODS
Thirty patients referred for treatment of acute severe CO poisoning who demonstrated carboxyhemoglobin (COHb) levels >25%, with simultaneous determinations of arterial hemoglobin oxygen saturation by pulse oximetry (SpO2) and arterial blood gas (ABG) techniques.


RESULTS
COHb levels and measurements of arterial oxygenation from pulse oximetry, ABG analysis, and laboratory CO oximetry were compared. SpO2 did not correlate with COHb levels. SpO2 consistently overestimated the fractional arterial oxygen saturation. The difference between arterial hemoglobin oxygen saturation (SaO2) calculated from ABG analysis and SpO2 increased with increasing COHb level.


CONCLUSIONS
Presently available pulse oximeters overestimate arterial oxygenation in patients with severe CO poisoning. An elevated COHb level falsely elevates the SaO2 measurements from pulse oximetry, usually by an amount less than the COHb level, confirming a prior observation in an animal model. Accurate assessment of arterial oxygen content in patients with CO poisoning can currently be performed only by analysis of arterial blood with a laboratory CO-oximetry.
Hampson
N B
NB
Section of Pulmonary and Critical Care Medicine, Virginia Mason Medical Center, Seattle, WA 98111, USA. cidnbh@vmmc.org
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002249:Carbon Monoxide Poisoning / Q000097:blood* / Q000209:etiology / Q000628:therapy; D002263:Carboxyhemoglobin / Q000378:metabolism*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006931:Hyperbaric Oxygenation; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index
D006454:Hemoglobins; C100003:deoxyhemoglobin; D002263:Carboxyhemoglobin