The objective Of this Study was to determine the relationship between carboxyhemoglobin (COHb) formation, global oxygen transport. and cardiac performance in the acute phase of combined burn and smoke inhalation injury. Following a third degree burn of 20% of the total body Surface area, adult sheep were subjected to cotton smoke (4 x 12 breaths) according to an established protocol. Compared with baseline (BL), the burn injury led to an immediate and sustained COHb-independent depression in myocardial contractility. Despite a progressive increase in COHb formation, Lip to a maximum of 78 +/- 3% (P < 0.001 vs BL), smoke inhalation did not further impair these hemodynamic changes. This study demonstrated that in the early stage of combined burn and smoke inhalation injury. the depression in cardiac function is basically triggered by the burn injury, whereas COHb generation secondary to cotton smoke exposure primarily contributes to pulmonary shunting. (C) 2004 Elsevier Inc. All rights reserved.