Carboxyhemoglobin formation following smoke inhalation injury in sheep is interrelated with pulmonary shunt fraction.
Carboxyhemoglobin (COHb) formation is triggered by the inducible isoform of heme oxygenase (HO-1) catalyzing carbon monoxide (CO) production through breakdown of heme molecules, exposure to CO or both. In the setting of CO poisoning, COHb is regarded as a reliable marker characterizing both severity of injury and efficacy of treatment strategies. This study was designed as a prospective laboratory experiment to elucidate potential interdependencies between COHb generation, oxygenation, and pulmonary shunt fraction (Qs/Qt) in an ovine model of smoke inhalation injury. Chronically instrumented ewes (n=15) were repeatedly subjected to cotton smoke (4 x 12 breaths) according to an established protocol. This approach resulted in a progressive increase in COHb formation that was interrelated with the degree of Qs/Qt (P<0.001) and inversely correlated with both arterial and mixed venous HbO(2) saturation (r=-0.96 and -0.93). Although the arteriovenous COHb gradient successively decreased over time, COHb determined in venous blood underestimated the arterial content.
Westphal
Martin
M
Department of Investigational Intensive Care Unit and Shriners Hospital for Children, University of Texas Medical Branch, Galveston, TX, USA. Martin.Westphal@gmx.net
Morita
Naoki
N
Enkhbaatar
Perenlei
P
Murakami
Kazunori
K
Traber
Lillian
L
Traber
Daniel Lee
DL
D000714:Anastomosis, Surgical; D000818:Animals; D001158:Arteries / Q000378:metabolism; D002249:Carbon Monoxide Poisoning; D002263:Carboxyhemoglobin / Q000378:metabolism*; D005260:Female; D008168:Lung / Q000473:pathology; D010100:Oxygen / Q000378:metabolism; D012756:Sheep; D015208:Smoke Inhalation Injury; D013997:Time Factors; D014680:Veins / Q000378:metabolism
D002263:Carboxyhemoglobin; D010100:Oxygen