title: Inaccurate pulse CO-oximetry of carboxyhemoglobin due to digital clubbing: case report.
abstract: Newer pulse CO-oximeters provide a non-invasive and quick means of measuring oxyhemoglobin, carboxyhemoglobin and methemoglobin. Clubbing has been reported to cause inaccuracy in pulse oximeters. We present a case of inaccurate carboxy-hemoglobin measurement by pulse CO-oximetry due to digital clubbing. An 18-year-old man with a history of cystic fibrosis presented after a suicide attempt by inhalation of exhaust. At the initial emergency department evaluation, his blood carboxyhemoglobin was 33%. He was intubated, placed on 100% oxygen and transferred to our facility. Upon arrival, we placed three different pulse CO-oximeters on different fingers and toes. Carboxyhemoglobin levels measured by these meters ranged from 9%-11%. A venous blood gas drawn on arrival showed a carboxyhemoglobin level of 2.3% after four hours on 100% oxygen by endotracheal tube. Thirty minutes later, we checked arterial blood gas, which revealed a COHb level of 0.9%. Again, non-invasive carboxyhemoglobin measurements read 10%. The patient was treated with hyperbaric oxygen for carbon monoxide poisoning. This case suggests that non-invasive measurements of carboxyhemoglobin should be correlated with the clinic history and with an arterial or venous blood gas oximetry analysis.
authors.forename: Nicole
authors.initials: N
authors.lastname: Harlan
authors.forename: Lindell K
authors.initials: LK
authors.lastname: Weaver
authors.forename: Kayla
authors.initials: K
authors.lastname: Deru
mesh_terms: D000293:Adolescent; D001784:Blood Gas Analysis / Q000379:methods; D002263:Carboxyhemoglobin / Q000032:analysis*; D003550:Cystic Fibrosis / Q000097:blood / Q000150:complications; D006801:Humans; D008297:Male; D010004:Osteoarthropathy, Primary Hypertrophic / Q000097:blood / Q000150:complications*; D010092:Oximetry / Q000295:instrumentation*; D013406:Suicide, Attempted
chemical_list: D002263:Carboxyhemoglobin