OXYGEN-CONSUMPTION AND DELIVERY RELATIONSHIP IN BRAIN-DEAD ORGAN DONORS

The oxygen delivery (DO2) and consumption (V over dot O-2) relationshi p in brain-dead organ donors is unknown. Therefore, in a prospective s tudy, we determined the DO2/V over dot O-2, relationship in 21 consecu tive brain-dead patients. Patients were allocated to one of two groups , according to plasma lactate concentration: normal (group NL, n = 11) or high (>2.5 mmol litre(-1)) (group HL, n = 10). V over dot O-2 was measured independently, using indirect calorimetry, under control cond itions, during low DO2 challenge with PEEP administration, and high DO 2 challenge with inflation of medical antishock trousers and volume ex pansion or blood transfusion, as required. Under control conditions, t here were no significant differences between groups NL and HL in haemo dynamic or oxygenation variables, both groups having a low V over dot O-2 (mean 114 (SD 21) ml min(-1) m(-2)). In group HL there was a diffe rent DO2/V over dot O-2, relationship pattern, with a dependent V over dot O-2, only. The mean slope of the DO2/V over dot O-2, relationship was significantly higher in group HL than in group NL (0.12 (0.09) vs 0.04 (0.07), P < 0.05). We conclude that brain death was associated w ith a low V over dot O-2, and patients in group HL exhibited DO2/V ove r dot O-2, dependency which was not observed in patients in group NL.