To Study The Correlation Between Activated Clotting Time And Hypothermia In Pediatric Patients Undergoing Cardiopulmonary Bypass

Abstract

Background: Cardiopulmonary bypass is a form of extracorporeal circulation whose function is to temporarily give   circulatory and respiratory support along with temperature management to facilitate surgery on the heart and great vessels. Depending on the duration and extent of artificial surface exposure, anticoagulation is necessary in order to avoid the formation of thrombus in the cardiopulmonary bypass circuit. The fundamental principle underlying the use of hypothermia with CPB is decreasing temperature to reduce metabolic activity. The ACT is commonly used to assess the therapeutic effects of anticoagulant medications prior to the initiation of CPB.

Aim: This study aims to study the correlation between activated clotting time and hypothermia in pediatric patients undergoing cardiopulmonary bypass.

Materials And Method: It is a prospective study of 50 pediatric patients ,who underwent cardiac surgery using cardiopulmonary bypass at tertiary cardiac care center. Pediatric patients aged between 0 to 10 years were included in this study. Adult patients undergoing cardiopulmonary bypass, emergency surgeries and heparin resistance patients are excluded from this study. Heparin dosage, CPB duration, aortic cross clamp time, added priming solution, Activated clotting time and temperature of baseline , initiation of cardiopulmonary bypass, during cardiopulmonary bypass , termination of cardiopulmonary bypass and protamine infusion were taken.

Results: Fifty paediatric patients underwent first time cardiopulmonary bypass were investigated. In which the baseline mean ACT was 150.24±26.617 secs at mean temperature of 36.466±0.3068⁰C. After initiation of cpb, the mean ACT increased as 753.12±29.979 secs at mean temperature of 32.308±0.9940⁰C this was due to the addition of 300- 400 USP units/kg heparin sodium injection (5000 I.U/ml), injected in the central venous line of a patient five minutes before the initiation of CPB . During CPB the mean ACT further increased as 937.18±39.301secs at mean temperature of 23.002±3.6488⁰C this prolongation was due to the decreased temperature. Here the P<0.005 which proved significant. The mean ACT decreased as 665.78±38.054 secs at termination of cpb with mean temperature of 35.164±0.3789⁰C, this decrease is due to rewarming.

CONCLUSION: In this study we observed that the activated clotting time correlate well with hemodilution and hypothermia. The activated clotting time increases with decrease in temperature and decreases with increase in temperature. Decrease in temperature make the clotting factors less functional and increases the activated clotting time. Increase in temperature increases metabolic activity thus increases the function of clotting factors resulting in decreased activated clotting time.