Cerebral oxygenation during warming after cardiopulmonary bypass
Sapire, K.J.; Gopinath, S.P.; Farhat, G.; Thakar, D.R.; Gabrielli, A.; Jones, J.W.; Robertson, C.S.; Chance, B.
Critical Care Medicine 25(10): 1655-1662
1997
ISSN/ISBN: 0090-3493 PMID: 9377879 Document Number: 475165
Objectives: To evaluate jugular venous oxygen saturation (Sj ovrhdot VO-2), measured with a fiberoptic oximetry catheter, and brain tissue oxygen saturation, measured by near-infrared spectroscopy (NIRSO-2), as monitors of cerebral oxygenation during cardiopulmonary bypass surgery. Design: Prospective, clinical study. Setting: Operating room of a Veterans Administration Hospital. Patients: Nineteen patients undergoing moderate hypothermic cardiopulmonary bypass surgery. Interventions: Sj ovrhdot VO-2 and NIRSO-2 were monitored in the patients during the surgical procedure. Measurements and Main Results: Moderate hypothermic cardiopulmonary bypass surgery had two distinct cerebral hemodynamic phases. While the patients were hypothermic, Sj ovrhdot VO-2 averaged 80 +- 7% and none of the patients had an increase in cerebral lactate production. During the rewarming period, however, reductions in Sj ovrhdot VO-2 lt 50% occurred in 16 (84%) patients and increased cerebral anaerobic metabolism developed in 11 (58%) patients. Sj ovrhdot VO-2 during rewarming was dependent on mean arterial pressure, with 60 mm Hg appearing to be a critical value. Two other factors appeared to also contribute to the jugular desaturation, a low hematocrit and a rapid warming time. The Sj ovrhdot VO-2 catheter had excellent performance during the surgery. The average difference between paired measurements of Sj ovrhdot VO-2 by the catheter and in blood samples was -0.4 +- 4.25%, and the correlation between the two measurements was highly significant (r-2 = .93; p lt .001). The NIRSO-2 trended with the Sj ovrhdot VO-2 in most patients (r-2 = .63; p lt .001). Conclusions: The study confirms other studies showing that jugular venous desaturation can occur during rewarming after cardiopulmonary bypass surgery. Presently, Sh ovrhdot VO-2 appears to be a better monitor of cerebral oxygenation than NIRSO-2. However, NIRSO-2 has promise as a noninvasive monitor of cerebral oxygenation if future developments allow more quantitative measurements of oxygen saturation.