EFFECTS OF BLOOD-TRANSFUSION ON OXYGEN-TRANSPORT VARIABLES IN SEVERE SEPSIS

Objective. To investigate whether increasing oxygen delivery (Do2) by increasing hematocrit results in increases in oxygen uptake (Vo2) in s eptic patients with an abnormal Do2/Vo2 relationship. Design: Prospect ive, randomized, interventional crossover study. Setting. Tertiary car e hospital. Patients: A consecutive sample of 16 patients admitted to the intensive care unit, who were diagnosed as having severe sepsis by defined criteria and who had a hemoglobin concentration of <10 g/dL. Interventions. Patients received, in random order, an infusion of dobu tamine (10 mug/kg/min) and a blood transfusion (800 mL of packed red b lood cells in 90 mins). Hemodynamic and oxygen transport variables wer e determined before and after each treatment, allowing at least 20 min s during the infusion of dobutamine to achieve the steady state. Measu rements and Main Results. Changes in Do2 and Vo2 induced by each inter vention were measured. Dobutamine significantly increased DO2 (48.5 +/ - 6.9%; p = .0001) and Vo2 (21.7 +/- 3.3%; p = .0001). Blood transfusi on increased Do2 (21.4 +/- 4.3%; p .005) but Vo2 did not change signif icantly (2.2 4.1%). Correlation coefficients for the percent changes o f Do2 and Vo2 (r2 = .67, p = .001 for dobutamine; and r2 = 21, p =.07 for blood transfusion) were significantly different for each treatment (p = .0001). Conclusions: . In patients with an abnormal Do2-dependen t Vo2, as shown by increases in Vo2 brought about by an infusion of do butamine, blood transfusion does not significantly increase Vo2, despi te significant changes in Do2. The Vo2, in some critically ill patient s, depends more on blood flow than on global Do2.