Preservation Of LIPO-PGE₁ On Platelets During Cardiopulmonary Bypass In Cardiac Valve Replacement

Objective The present study was designed to investigate the effects of liposomal prostaglandin E₁(Lipo-PGE₁) on platelets function in cardiac valve replacement during cardiopulmonary bypass.Methods A total of 20 patients who were received cardiac valve replacement (12 for mitral valve replacement and 8 for aortic valve replacement) undergoing cardiopulmonary bypass(CPB) were randomized into two groups: group C(n= 10) and group L(n=10). In group L, patients were administered 10 ng·kg^-1·min^-1 of Lipo-PGE₁ and some other Lipo-PGE₁ was added to the priming solution(10 ng/ml) of the extracorporeal circulation machine.In group C, patients were only administered the same volume of normal saline with the same method. Plasma levels of α -granule membrane protein-140(GMP-140), thromboxane B₂ were measured with peripheral arterial blood before incision(T₁), at 30 minutes of CPB(T₂), 1 hour after CPB (T₃), 2 hour after CPB(T₄) and 24 hour after CPB(T₅) respectively. Levels of GMP-140 and TXB₂ were all measured by enzyme-linked immunosorbent assays (ELISA). Platelet count was observed at T₁, T₂, T₃ and T₅, and the maximum platelet aggregation rate(Pagg) induced by ADP was determined atti(i.e.T,)> t2(i.e.T2)> t3(the end of CPB)> Uile.T3), t5(i.e.T4) and t^i.e.Ts) respectively.Results (1) There were no significant differences between two groups in age, body weight, sex ratio, the lowest nasopharyngeal temperature, total CPB duration, aorta clamping duration and surgery duration. (2) GMP-140: The plasma GMP-140 levels were higher than the baseline at T2^T4(P<0.05) in group C, however, the values in group L were higher than the baseline only at Tj> T4. The values in group L at T2 ^T4 were lower than those in group C and there were significant differences between group L and group C. (3) TXB2: The plasma levels of TXB2 were higher than the baseline from T2 to Ti(P<0.05) in group C but the values in group L were higher than the baseline only at T^> T4. The values in group L at T2 ^T4 were obviously lower than those in group C. (4) Postoperative blood loss: The blood loss of postoperation was reduced remarkably in group L(246.7± 34.4ml) as compared with that in group C(387.5±75ml). (5) Platelet count: The platelet counts of two groups were all remarkably lower than baseline from T2 to T5 (P<0.01). The platelet count in group L was higher as compared with that in group C from T2 to Ts, but there were no significant differences between two groups(P>0.05). (6) The maximum platelet aggregation rate(Pagg): Pagg induced by ADP was greatly decreased at t2^ti in both groups, and it was remarkably higher in group L as compared to group C from t2 to U-Conclusion (1) The plasma levels of GMP-140, TXB2, were higher significantly during CPB. The platelet count and Pagg were lower obviously during CPB. These findings indicated the function of platelet was damaged. (2) Lipo-PGEi can protect platelets from unwanted activation during CPB surgery and reduce the blood loss of postoperation.