THE RELATIONSHIP OF OXYGEN-CONSUMPTION MEASURED BY INDIRECT CALORIMETRY TO OXYGEN DELIVERY IN CRITICALLY ILL PATIENTS

Objective: The existence of oxygen supply dependency, defined as oxyge n consumption (Vo(2)) limited by oxygen delivery (Do(2)), is still que stioned, This study examined the relationship between Vo(2) and Do(2) in two groups of critically ill surgical patients 50 years and older i n the first 24 hours of resuscitation after pulmonary artery catheter insertion, Group 1 patients had systemic inflammatory response syndrom e (SIRS), sepsis, severe sepsis, septic shock, and adult respiratory d istress syndrome (ARDS), Group 2 patients had hemorrhagic shock. Metho dology: Study methodology included (1) augmenting Do(2) with fluids, b lood: and vasopressors, (2) measuring Vo(2) by indirect calorimetry to avoid the problem of mathematical coupling with Do(2) calculation, an d (3) analyzing data during steady states of temperature, sedation, pa ralyzing agents, and vasopressors. Results: Six to 18 measurements col lected on all study patients during a period within the first 24 hours were analyzed using a linear regression analysis, Statistical signifi cance was set at p less than or equal to 0.05. Seven of nine patients in group I demonstrated positive, statistically significant relationsh ips between Vo(2) and Do(2). Of six patients in group 2, one patient d emonstrated a positive, significant relationship of Vo(2) and Do(2), t hree demonstrated inverse relationships, and two patients did not show a Do(2)/Vo(2) relationship. Supply dependency did not exist in all pa tients but was present in seven out of nine patients with systemic inf lammatory response syndrome, sepsis, severe sepsis, septic shock, and adult respiratory distress syndrome in the first 24 hours of treatment .