Slight Robert D, Bappu Norzeihan J, Nzewi Onyekwelu C, McClelland D Brian L, Mankad Pankaj S
Department of Cardiothoracic Surgery, The Royal Infirmary of Edinburgh, Little France Crescent, Edinburgh, Scotland, United Kingdom.
Transfusion. 2006 Mar;46(3):392-7. doi: 10.1111/j.1537-2995.2006.00734.x.
Current blood prescription in cardiac surgery is based largely on hemoglobin (Hb) concentration. Hb may not provide a reliable guide to the patient's red cell (RBC) volume (RCV) during cardiac surgery as a consequence of the high fluid loads infused. This study provides estimates of the perioperative changes in RCV, plasma volume (PV), and blood volume (BV) with a view to developing a more accurate way of assessing a patient's need for transfusion.
Thirty adult elective cardiac surgery patients were recruited to the study. The preoperative RCV was calculated by use of a standard nomogram. Losses and gains in RCV at several time points were added or subtracted from the baseline value. Estimates of PV and BV were derived from patient hematocrit level and RCV for each time point.
The greatest perioperative loss of RCV occurred during cardiopulmonary bypass (CPB); however, half of this loss was returned to the patient at the end of CPB. A net gain of RCV occurred during the period of intensive care management. PV and BV showed two distinct peaks, immediately after CPB and at 16 hours after intensive therapy unit return.
PV and BV expansion are significant factors that may lead to a Hb value that is misleadingly low in that it overestimates the decrease in RCV. This effect could lead to unnecessary transfusion if the RBC transfusion threshold is based only on Hb concentration.
目前心脏手术中的输血方案很大程度上基于血红蛋白（Hb）浓度。由于术中输入大量液体，Hb可能无法可靠地反映心脏手术患者的红细胞（RBC）容量（RCV）。本研究旨在评估围手术期RCV、血浆容量（PV）和血容量（BV）的变化，以期找到一种更准确的方法来评估患者的输血需求。
招募30例择期心脏手术成年患者。术前RCV通过标准列线图计算得出。在几个时间点，将RCV的增减量与基线值相加或相减。每个时间点的PV和BV通过患者血细胞比容水平和RCV估算得出。
围手术期RCV的最大损失发生在体外循环（CPB）期间；然而，CPB结束时，这一损失的一半又回到了患者体内。在重症监护管理期间，RCV出现净增加。PV和BV在CPB后即刻以及返回重症监护病房16小时出现两个明显的峰值。
PV和BV的增加是导致Hb值被误导性地降低的重要因素，因为它高估了RCV的减少。如果仅根据Hb浓度设定红细胞输血阈值，这种影响可能导致不必要的输血。
