Profound Hypothermia-Induced Platelet Dysfunction during Heparinized Cardiopulmonary Bypass

(Department of Cardiovascular Surgery, Institute of Clinical Medicine, Tsukuba University, Tsukuba, Japan and Tsukuba Medical Center Hospital*, Tsukuba, Japan)

Osamu Shigeta Yuji Hiramatsu Tomoaki Jikuya*
Yuzuru Sakakibara
There is an impression among cardiothoracic surgeons that the technique of profound hypothermic circulatory arrest (PHCA) is associated with an increased bleeding tendency compared to conventional bypass surgery. In addition to the recognized factors contributing to the hemorrhagic tendency seen in moderate hypothermic cardiopulmonary bypass (CPB), it is likely that the lower temperature utilized in PHCA may exacerbate platelet dysfunction. In this report, platelet counts and functions at the same cardiopulmonary bypass time were compared in human PHCA surgery (hypothermia group, n16) and moderate hypothermic cardiopulmonary bypass surgery (control group, n20). Mean platelet count corrected by hematocrit in the hypothermia group at 2 h of CPB was significantly lower than in the control group (3.7~104µl vs. 11.4~104/µl, p0.0001). In the hypothermia group, there were significant increases in the percentage of GMP-140 (P-selectin)-positive platelets (11.8% vs. 8.3%, p0.0091) at 1 h of CPB, and also in microparticles (24.8% vs. 10.5%, p0.0001) and aggregated platelets (3.4% vs. 1.4%, p0.0058) at 2h of CPB. Profound hypothermic circulatory arrest used in surgery for aortic arch aneurysm or dissection may cause irreversible platelet dysfunction and contribute to hemorrhagic tendency during the surgery. To minimize platelet dysfunction during CPB, the lowest blood temperature should be maintained above 15°C.
@Jpn. J. Cardiovasc. Surg. 33: 147-151 (2004)