Relationship between Oxygen Uptake and Mixed Venous Oxygen Saturation in the Immediate Postoperative Period

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Abstract

Background

During muscular exercise, a negative correlation has been demonstrated between the value of mixed venous oxygen saturation (SJOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2) and the level of muscular work, expressed at each level as the ratio of oxygen uptake (JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2) to each subject's maximal oxygen uptake (JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2max). Because the immediate postoperative period is associated with an increase in whole body oxygen demand, and in this regard resembles the effects of muscular exercise, a similar correlation may exist during this period.

Methods

JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2max was determined in 11 patients 3–5 days before coronary artery bypass surgery. During the first 2 postoperative h, JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 and SJOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 were monitored. JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 was measured by indirect calorimetry and SJOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 by a fiberoptic pulmonary arterial catheter.

Results

The highest postoperative value of JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 was most often associated with visible shivering and ranged among patients from 19% to 53% of preoperatively measured JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2max. There was a highly significant negative correlation between SJOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 and the ratio JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2/JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2max. This correlation was observed when data were examined collectively (136 simultaneous determinations of the two variables) and at the individual level (10–18 determinations for each patient). The slopes and the y intercepts of individual lines of correlation were within a narrow range.

Conclusions

During the first 2 postoperative h after coronary artery bypass surgery, JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 rarely exceeds 50% of preoperative JOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2max. Assuming a stable state of myocardial function, SJOURNAL/anet/04.02/00000542-199402000-00007/ENTITY_OV0312/v/2017-07-22T060123Z/r/image-pngO2 measurement may provide an indirect means of assessment of the “exercise test” imposed on patients recovering from general anesthesia.

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