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Moderate hypothermic versus normothermic total cardiopulmonary bypass for coronary artery surgery: a retrospective
R J Massimino1, G T Stearns, J D Gough
1Division of Cardiovascular Surgery, Brown University Program in Medicine, Providence, Rhode Island.
Insights
Moderate hypothermic perfusion during coronary artery bypass surgery led to lower cardiac index and oxygen transfer compared to normothermic perfusion. Both methods were comparable in terms of morbidity and mortality outcomes.
Area of Science:
- Cardiovascular Surgery
- Cardiopulmonary Bypass
- Physiology
Background:
- Coronary artery bypass surgery (CABS) is a common procedure requiring cardiopulmonary bypass (CPB).
- The impact of perfusate temperature during CPB on patient outcomes remains an area of investigation.
- Normothermia and moderate hypothermia are two common CPB temperature strategies.
Purpose of the Study:
- To compare morbidity and mortality in patients undergoing CABS with normothermic versus moderate hypothermic CPB.
- To evaluate physiological differences, including cardiac index and oxygen transfer, between the two perfusion strategies.
Main Methods:
- Retrospective analysis of 200 patients who underwent CABS between 1987 and 1990.
- Patients were divided into two groups: moderate hypothermia (28-32°C, n=100) and normothermia (37°C, n=100).
- Comparison of demographic data, perfusion time, cardiac index, mean arterial pressure, and oxygen transfer.
Main Results:
- The moderate hypothermia group (Group H) exhibited a significantly lower cardiac index (2.32 L/m²/min) compared to the normothermic group (Group N) (2.55 L/m²/min) (p<0.001).
- Oxygen transfer was significantly higher in the normothermic group (159 cc/min) versus the hypothermic group (113 cc/min) (p<0.001).
- Mean arterial pressure was higher in Group H (69 mmHg) than Group N (63 mmHg) (p<0.001), with Group H requiring vasodilators and Group N requiring vasoconstrictors.
Conclusions:
- Moderate hypothermic perfusion during CABS was associated with reduced cardiac index and oxygen transfer compared to normothermic perfusion.
- No metabolic acidosis was observed in either group.
- Further research is needed to correlate these physiological findings with long-term morbidity and mortality outcomes.
Abstract:
A retrospective analysis of 200 patients who underwent coronary artery bypass surgery between 1987 and 1990 was performed to ascertain whether there was any difference in morbidity or mortality with normothermic versus moderate hypothermic perfusion. Total cardiopulmonary bypass was used in all patients. 100 patients (Group H) were perfused using moderate (28-32 degrees C) hypothermia and the remaining 100 patients (Group N) were perfused at normothermia (37 degrees C). Both groups were comparable for age, weight, BSA, and perfusion time (Group H-mean 64 years, 82 Kg., 1.92 m2, 94 minutes; Group N-mean 63 years, 82 Kg., 1.90 m2, 90 minutes). Mean perfusate temperature in Group H was 31 degrees C, while the normothermic group was maintained at 37 degrees C. Both groups were perfused to maintain a venous oxygen saturation between 65-70 percent and arterial pressure between 60-70 mmHg. The cardiac index during bypass for Group H was lower (2.32 +/- .19 L/m2/min) than Group N (2.55 +/- .11 L/m2/min) (p less than 0.001). Mean arterial pressure for Group H was 69 +/- 12.4 mmHg and for Group N was 63 +/- 7.8 mmHg (p less than 0.001). Oxygen transfer for Group N (159 +/- 43 cc/min) was higher than Group H (113 + 31cc/min) (p less than .001). Metabolic acidosis was not observed in either group. Group H required vasodilators while Group N required vasoconstriction to maintain pressures on total bypass between 60-70 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)