The latter represents the time that the net cumulative Vo2 became positive, indicating that the oxygen debt had been repaid. The magnitude and duration of the Vo2 deficit were greatest with nonsurvivors, slightly less in survivors with organ failure, and least in survivors without organ failure.
Oxygen Deficit in a Randomized Clinical Trial
The mean (± SD) of preoperative and postoperative values of important variables of the control and protocol groups are summarized in Table 4. The oxygen debt was calculated in a prospective randomized study that tested the effect of supranormal values empirically observed in the survivors in a group of critically ill surgical patients. The oxygen debt in 29 control patients, who had normal values as their therapeutic goals, averaged 17.3 ±6.8 L/m2 (±SE) at its maximum value, which occurred 31 h after surgery; this oxygen debt persisted for more than 48 h. By contrast, the maximum oxygen debt of 27 protocol patients, who had the supranormal values as their goals of therapy, was 7.6 ±3.4 L/m2 at its peak, which occurred 3 h after surgery; this oxygen debt persisted for an average of 13 h. These differences were statistically significant by Students unpaired t test. Then (34 percent) of 29 control patients died with 31 organ failures, while one (4 percent) of the 27 protocol patients died (p<0.05) with one organ failure (p<0.01). The data indicate that when oxygen deficit was minimized and promptly corrected by optimizing physiologic compensations, organ failure and mortality were reduced.
Table 4—Selected Hemodynamic and Oxygen Transport Values of Prospective Series
|Variables*||Control Croup||Protocol Croup|
|MAP, mm Hg||95± 19||87 ±24||94± 16||90± 18|
|Heart rate, beats per min||89 ±19||101 ±21||85± 14||103 ±20|
|Pulm art occlusive pressure, mm Hg||10 ±6||12 ±5||9±4||11 ±6|
|Cl, L/min/m*||3.5±0.8||3.6± 1.1||3.6±0.7||4.2±1.2t|
|Hematocrit, percent||35±4||34±3||37 ±4||34±4|
|Do2) m l/min/m2||540 ±130||560 ±191||586 ±91||666±131f|
|Voa, ml/min/m2||122 ±31||120 ±43||113 ±24||135 ± 441-|