Moderate versus deep hypothermia for the arterial switch operation--experience with 100 consecutive patients.

OBJECTIVES

To evaluate the impact of moderate versus deep perioperative hypothermia on postoperative morbidity in patients receiving the arterial switch operation (ASO).

METHODS

One hundred consecutive patients received the ASO from 9/98 to 4/06 using temperature-corrected full-flow moderate (M>24 degrees C, n=51) or deep hypothermic cardiopulmonary bypass (CPB) (D <20 degrees C, n=49). Complex TGA morphology was present in 33 patients (M: 27.4%, D: 38.8%, n.s.). Median age was 9 days (M) versus 10 days (D) and body weight was 3.5+/-0.7 kg (M) versus 3.6+/-0.9 kg (D) (both p=n.s.). Follow-up was 3.7+/-2.1 years.

RESULTS

Lowest perioperative rectal temperature was 25.3+/-1.1 degrees C (M) versus 19.0+/-0.8 degrees C (D), p<0.001. Intraoperative blood transfusion (M: 231+/-47 ml, D: 252+/-112 ml, p=0.04) and postoperative lactate level (M: 3.2+/-1.3 mmol/l, D: 3.8+/-2.4 mmol/l, p=0.02) were lower under moderate hypothermia. One patient (D) suffered myocardial ischemia, required ECMO support and died. All other patients were safely weaned from CPB using dopamine (M: 3.0 microg/kg min, D: 3.4 microg/kg min, n.s.) and dobutamine (M: 5.6 microg/kg min, D: 6.7 microg/kg min, p=0.048). Secondary chest closure was performed in 41% (M) versus 59% (D) (p=0.04). Patients were extubated after 89 h (M) versus 126 h (D) (p=0.03). Under moderate hypothermia ICU stay (M: 8.4+/-4.7 days, D: 12.0+/-13.8 days, p=0.03) and hospital stay (M: 12.8+/-6.8 days, D: 20.7+/-15.5 days, p=0.001) were shorter. Five-year freedom from reoperation was 97.0% for simple and 85.2% for complex TGA with RVOT reconstruction in 4/6 patients.

CONCLUSIONS

The ASO under full-flow moderate compared to deep hypothermia was advantageous regarding length of procedure and primary chest closure rate. Moderate hypothermia seemed to be beneficial for pulmonary recovery, length of chest tube drainage treatment and inotropic support. No worse early or long-term effects of moderate hypothermia were found.