The Dilemma of Cold Agglutinins In Pediatric Cardiac Surgery Patients Requiring Hypothermia: Our Experience with Four Patients
Authors: Saeed Haleema , Hord Jeffrey 
Published: October 2019

Abstract
Abstract 5133
Red Cell Erythropoiesis Structure and Function, Metabolism, and Survival (Excluding Iron)

Introduction:
Cold agglutinins are antibodies, usually IgM, that react at low temperatures. These can be of great concern during procedures like cardiothoracic surgery where hypothermia is required to minimize damage to the myocardium. Cold agglutinins may result in hemolysis or vaso-occlusive phenomenon leading to serious sequelae like myocardial infarction, renal and hepatic insufficiency and cerebral damage. There is no published literature on the significance of cold agglutinins in pediatric patients requiring cooling during cardiopulmonary bypass. With the increasing number of complex cardiac surgeries done in pediatric patients, pediatric hematologists are increasingly asked how best to approach this problem. We would like to present our approach to this problem in four patients at our center.

Methods:
Retrospective chart review of patients presenting to our center with cold agglutinins and requiring cooling for cardiac surgery.

Results:
We evaluated four patients over the last 3 years that required cardiac surgery with planned hypothermia who were found to have cold agglutinins on routine preoperative screening. A summary of our findings are presented in presented in table 1.
Case 1: After waiting almost a year, further testing was done that revealed that the patient had Anti-P anti body that was reactive at 4 degree. He was cooled to only 32 degrees during the procedure and was given only P negative blood. He demonstrated no signs of hemolysis with normal hemoglobin and billirubin postoperatively.
Case 2: This patient developed cold agglutinins secondary to mycoplasma infection as proved by an elevated M.pneumonia IgM level. She required surgery urgently due to heart failure. She was initially treated with oral corticosteroids for 10 days. There was still 3+ agglutination in all 3 tubes at 4 degrees. She then underwent a two volume exchange transfusion. Post transfusion and preoperatively she was weakly positive in all 3 tubes at 4 degree but negative in 2/3 tubes at 8 degrees. She was cooled to 7 degrees during the procedure without any signs of hemolysis or vaso-occlusion.
Case 3: This patient demonstrated alloanti M antibodies at room temperature and 4 degrees in addition to non specific antibodies only at 4 degrees. These results were unchanged after a 14 day course of steroids. Her temperature was kept at 32 degrees and she was transfused M negative blood. Hemoglobin and billirubin remained stable.
Case 4: This patient had an anti P antibody that was reactive at 4 degrees. He was cooled to 28 degrees without agglutination.

Conclusion:
Cold agglutinins in cardiothoracic surgery patients are an increasing concern. The traditional wait and see approach has the disadvantage of unnecessary delay in surgery as well as the lack of an expected time course for how long to wait. We would recommend that antibody identification and thermal amplitude testing be done for these patients early to see if surgery can safely be performed at a higher temperature. In cases requiring urgent surgery corticosteroids or exchange transfusion can be considered. There is a need for further research about the natural course and nature of cold agglutinins in these patients.

Disclosures:
No relevant conflicts of interest to declare.