In Vivo Effects of Platelet Apheresis on Oxygen Metabolism in Pigs

Abstract

IntroductionPlatelet apheresis is a routine clinical practice. Although the efficacy of collected platelets has been studied, the impact of apheresis on the physiology of the donor is less clear. This study investigated oxygen metabolism in pigs during a 4 hour platelet apheresis as a prelude to initiating studies of hemorrhage and resuscitation in swine with reduced platelets.MethodsForty pigs (39.8±0.6 kg) were catheterized with a femoral vein catheter for platelet apheresis, using a Haemonetics MCS9000. Hemodynamics was recorded during the apheresis process. Arterial and venous samples were collected before and after apheresis for blood gases and CBC.ResultsDuring apheresis, blood‐withdrawing decreased MAP from 74<a name=”OLE_LINK2”></a><a name=”OLE_LINK1”>±</a>2 to 45±1 mmHg and increased heart rate from 104±3 to 129±4 bpm (both p<0.05); blood‐returning recovered MAP and HR to baseline values, with no changes observed in cardiac output. Platelet counts in pigs decreased to 40±3% of baseline values after 4 hours of apheresis (p<0.05). Pig blood glucose was increased by apheresis from 4.1±0.3mM to 5.2±0.2mM, Ca++ decreased from 1.34±0.01mM to 1.13±0.02mM, and lactate decreased from 2.2±0.1mM to 1.3±0.1mM (all p<0.05), with no changes in Hct, Hgb and RBCs. Oxygen delivery was not affected by apheresis, but oxygen extraction was decreased from 27±2% to 20±1%, and oxygen consumption was decreased from 4.0±0.2 O2/dL blood to 3.1±0.2 ml O2/dL blood (both p<0.05).ConclusionIn addition to reducing platelet counts, platelet apheresis caused large fluctuations in MAP and compromised oxygen metabolism, which can impact the physiologic response to hemorrhage in these animals.