G Fita1, C Gomar, I Rovira, M C Basora. 1. Servicio de Anestesiología y Reanimación, Hospital Clínic, Facultad de Medicina, Universidad de Barcelona.
Abstract
OBJECTIVE: Heart surgery with cardiopulmonary bypass (CPB) leads to changes in supply and consumption of cerebral oxygen (DO2 and VO2C). Monitoring jugular bulb oxygen saturation (SjO2) detects changes in the DO2C/VO2C ratio that occur in patients undergoing heart surgery. The objective of this study was to determine the evolution of SjO2, of the arteriovenous difference of cerebral oxygen and of cerebral oxygen extraction, as well as the possible relation between those variables and changes in mean arterial pressure, hemoglobin counts and temperature in patients undergoing heart surgery with CPB. PATIENTS AND METHOD: A prospective study carried out in 31 patients who underwent coronary valve surgery. To monitor SjO2, each patient's internal jugular vein was cannulated with an oximetric catheter in a retrograde direction to monitor SjO2. RESULTS: Baseline SjO2 (68 +/- 7.4%), obtained after anesthetic induction, was similar to SjO2 before (65 +/- 6%) and after (67 +/- 8.2%) CPB. However, SjO2 upon starting CPB (60 +/- 8.6%) and during rewarming (63 +/- 3%) were significantly lower than at baseline. SjO2 was significantly higher during hypothermic bypass (78 +/- 5%) than at baseline. SjO2 ranged from a low of 60 +/- 8% as CPB was initiated to a high of 78 +/- 5% during hypothermic CPB. Mean arterial pressure was significantly lower at the start of bypass (44 +/- 6 mmHg) than anesthetic induction (83.5 +/- 13.1 mmHg) and the decrease correlated with a significant decrease in SjO2. Changes in mean arterial pressure were unrelated to significant changes in SjO2 at other moments, however. Nor was there a significant relation between changes in temperature or hemoglobin and the evolution of SjO2. At least one episode of SjO2 desaturation (= 50%) occurred in 29% of the patients, with the lowest values being recorded at the start of CPB and during rewarming. CONCLUSIONS: The greatest risk of cerebral oxygen imbalance between supply and demand occurs at the start of CPB and during rewarming, as shown by decreases in SjO2 levels below baseline at those times.
OBJECTIVE: Heart surgery with cardiopulmonary bypass (CPB) leads to changes in supply and consumption of cerebral oxygen (DO2 and VO2C). Monitoring jugular bulb oxygen saturation (SjO2) detects changes in the DO2C/VO2C ratio that occur in patients undergoing heart surgery. The objective of this study was to determine the evolution of SjO2, of the arteriovenous difference of cerebral oxygen and of cerebral oxygen extraction, as well as the possible relation between those variables and changes in mean arterial pressure, hemoglobin counts and temperature in patients undergoing heart surgery with CPB. PATIENTS AND METHOD: A prospective study carried out in 31 patients who underwent coronary valve surgery. To monitor SjO2, each patient's internal jugular vein was cannulated with an oximetric catheter in a retrograde direction to monitor SjO2. RESULTS: Baseline SjO2 (68 +/- 7.4%), obtained after anesthetic induction, was similar to SjO2 before (65 +/- 6%) and after (67 +/- 8.2%) CPB. However, SjO2 upon starting CPB (60 +/- 8.6%) and during rewarming (63 +/- 3%) were significantly lower than at baseline. SjO2 was significantly higher during hypothermic bypass (78 +/- 5%) than at baseline. SjO2 ranged from a low of 60 +/- 8% as CPB was initiated to a high of 78 +/- 5% during hypothermic CPB. Mean arterial pressure was significantly lower at the start of bypass (44 +/- 6 mmHg) than anesthetic induction (83.5 +/- 13.1 mmHg) and the decrease correlated with a significant decrease in SjO2. Changes in mean arterial pressure were unrelated to significant changes in SjO2 at other moments, however. Nor was there a significant relation between changes in temperature or hemoglobin and the evolution of SjO2. At least one episode of SjO2 desaturation (= 50%) occurred in 29% of the patients, with the lowest values being recorded at the start of CPB and during rewarming. CONCLUSIONS: The greatest risk of cerebral oxygen imbalance between supply and demand occurs at the start of CPB and during rewarming, as shown by decreases in SjO2 levels below baseline at those times.