Hypothermic cardiopulmonary bypass without exchange transfusion in sickle-cell patients: a matched-pair analysis

OBJECTIVES: Sickle-cell patients undergo cardiopulmonary bypass (CPB) surgery in our institution without perioperative exchange transfusion. We sought to determine whether this protocol increased mortality or important sickle-cell-related complications.

METHODS: We adopted a 1:1 matched-pair case-control methodology to evaluate the safety of our protocol. Sickle-cell patients who underwent CPB between January 1995 and January 2014 were matched with haemoglobin AA (HbAA) controls according to sex, age, weight and type of cardiac procedure.

RESULTS: Thirty-three sickle-cell patients (21 HbAS, 7 HbSS and 5 HbSC) underwent CPB surgery using our institutional protocol. Sickle-cell patients and controls were similar according to the matching criteria. Preoperatively, haemoglobin SS (HbSS) and haemoglobin SC (HbSC) patients were anaemic (8.5 ± 1.4 vs 13.5 ± 1.9 g/dl; P <0.01 and 11.0 ± 0.6 vs 12.7 ± 0.9 g/dl; P = 0.01, respectively). Operative procedures included valve repair and replacement (12) as well as repair of congenital cardiac malformations (21). The duration of CPB and lowest CPB temperatures was similar for sickle-cell patients and controls. Systemic hypothermia (23.8-33.5°C), aortic cross-clamping, cold crystalloid antegrade cardioplegia and topical hypothermia were used in sickle-cell patients without complications. There was no acidosis, hypoxia or low cardiac output state. No mortality or important sickle-cell-related complications occurred. Although blood loss was similar between sickle-cell patients and controls, HbSS (unlike HbAS and HbSC) patients required more blood transfusion than controls (30.0 ± 13.3 vs 10.8 ± 14.2 ml/kg; P = 0.02) to counter haemodilution and replace blood loss. In-patient stay was similar for sickle-cell patients and controls.

CONCLUSIONS: Perioperative exchange transfusion is not essential for a good outcome in sickle-cell patients undergoing CPB. A simple transfusion regimen to replace blood loss is safe in HbSS patients; blood transfusion requirements for HbSC and HbAS patients undergoing CPB are similar to those of matched HbAA controls. The use of systemic hypothermia during CPB does not increase sickle-cell-related complications. Cold crystalloid cardioplegia and topical hypothermia provide safe myocardial protection without the need for more sophisticated measures.