Normothermia versus Hypothermia during Cardiopulmonary Bypass in Cases of Repair of Atrioventricular Septal Defect.

Background: Cardiopulmonary bypass (CPB) used for cardiac surgery is now uniformly carried out under normothermic conditions in adult patients; however, the temperature applied in pediatric CPB vary significantly, ranging from deep hypothermia to normothermia due to the lack of a consistent approach to CPB temperature in pediatric cardiac surgery, which is related to a lack of supportive evidence. Organs protection aim to decrease metabolic requirement and provide energy and oxygen, hypothermia has reached these goals by arresting and cooling the heart, delivering oxygen, and modifying reperfusion. Recently, a large number of studies investigated effect of hypothermia to decrease the negative impact of hypothermia. It has been suggested that the degree of hypothermia affects the inflammatory responses triggered by CPB. However, the use of normothermia during CPB had been introduced and resulted in acceptable results. We hypothesized that the use of normothermia during corrective surgery of AV septal defects improves the outcome of the CPB.

Objective: The study aimed to compare the outcome of normothermic technique and mild hypothermic technique during (CPB) in pediatric cardiac patients undergoing repair of atrioventricular (AV) septal defect and their effect on tissue perfusion, serum lactate level, duration of patient intubation, and postoperative hospital stay.

Patients and Methods: Forty patients presented for repair of AV defect aged from 1 month to 36 months were divided randomly into two equal groups (20 patients in each): Group I (Normothermic group) of body temperature more than 35°C up to 37°C and Group II (mild Hypothermic group) body temperature between (32°C-35°C). Basal data include complete blood count, electrolytes, arterial blood gases (ABGs), coagulation profile, and liver function tests were collected. Hemodynamic variables, ABG, serum lactate, and activated clotting time (ACT) measured in different time intervals related to CPB. With the termination of CPB, aortic cross-clamping time (minutes), CPB time (minutes), spontaneous regaining of the heart function, need for inotropic administration, and/or vasopressor requirements to wean the heart from CPB were reported in all patients.

Results: This study showed statistically significant lower PH and HCO3 levels and significantly higher serum lactate levels in Group II (hypothermic) than Group I (normothermic) after weaning from CPB. Furthermore, ACT level was statistically significantly higher in Group II than Group I after weaning of CPB. During postoperative period, hypothermic group showed significantly higher liver enzymes than the normothermic group. The duration of inotropes administration and duration of intubation were significantly longer in Group II than Group I.

Conclusion: Normothermia during CPB showed better global tissue perfusion than hypothermia in elective surgeries for repair of AV defects in the form of less degree of lactic acidosis, less effect on coagulation system, shorter duration of inotropic support, shorter intubation period, and shorter stay in the intensive care unit.