Suspected cold agglutination during mild hypothermic pediatric open heart surgery: a report of two cases.

Cold agglutination was suspected in 2 pediatric open heart surgery cases during mild hypothermic cardiopulmonary bypass. The first patient was a 2-year-old boy with secundum atrial septal defect. Fifteen minutes after the initiation of mild hypothermic cardiopulmonary bypass, the inlet pressure of oxygenator suddenly elevated from 250 to over 500 mmHg, whereas outlet pressure was maintained. The blood flow rate decreased from 140 to 85 ml/kg/min. At that time, the arterial blood temperature was less than 32°C. Cold agglutinin was highly suspected, so patient was immediately warmed, and the inlet pressure of oxygenator decreased to 250 mmHg when the arterial blood temperature reached to 36°C. Second patient was a 3-year-old boy with secondary developed subvalvular pulmonary stenosis after the repair of double chambered right ventricle at 10 months of his age. Eighteen minutes after the initiation of mild hypothermic cardiopulmonary bypass, the inflow pressure suddenly elevated to 500 mmHg and transmission flow decreased to 55 ml/kg/min. Twenty-three minutes after warming, the pressure fell to a normal level and transmission flow was recovered. The operation continued with normo-thermic cardiopulmonary bypass and crystalloid cardioplegia. Both cases had no postoperative complications related to cold agglutinin such as myocardial infarction, cerebral infarction, or renal insufficiency.