Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India.
Ann Card Anaesth. 2021 Jan-Mar;24(1):36-41. doi: 10.4103/aca.ACA_104_19.
A wide range of acid base fluctuations are seen during Cardiopulmonary bypass (CPB) and the development of metabolic acidosis is well recognized. We conducted a study tocompare the metabolic effects of Ringer lactate and Plasmalyte-A as CPB prime in causing bypass associated acidosis in valve replacement surgeries.
We performed a prospective, randomized controlled study on a total of 80 adult patients undergoing CPB for valvular heart surgeries. The patients were randomized into two groups: Group I (Ringer Lactate) and Group II (Plasmalyte-A). Arterial blood samples were taken before initiating CPB, 30 minutes after starting CPB, then every half hourly till termination of CPB and after half an hour stay in the ICU post operatively to analyze primarily H+ ions, bicarbonates, lactate and strong ion difference.
The results were analyzed in a quantitative manner. In Ringer Lactate group, during CPB, there was reduction in pH from 7.428 ± 0.029 at T1 to 7.335 ± 0.06 (P < 0.01) and 7.358 ± 0.06 (P < 0.01) at T2 and T3 respectively. Mean bicarbonates decreased in Ringer Lactate group during CPB from 24.28 ± 1.65 mEq/L at T1 to 20.98 ± 2.97 mEq/L at T2 (P < 0.01). In Plasmalyte-A group, mean pH, bicarbonate, strong ion difference (SID) were comparable at all time intervals (P > 0.05). In Ringer Lactate group, maximum surge in mean blood lactate levels was seen from 0.85 ± 0.35 mmol/l at T1 to 4.29 ± 1.78 mmol/L (P < 0.01) and 4.17 ± 1.28 mmol/L (P < 0.01) at T2 and T3, respectively. Such surge was not seen in Plasmalyte-A group. The mean SID decreased during the CPB in Ringer Lactate group from 41.102 mEq/L at T1 to 35.66 mEq/L (P = 0.033) at T2 implying metabolic acidosis. Numbered patients having hypotension and arrhythmias were also higher in Ringer Lactate group again indicating higher acidosis.
The different composition of Plasmalyte-A and Ringer Lactate have different metabolic implications for patients undergoing cardiac surgery. Patients who received Plasmalyte-A as cardiopulmonary bypass prime developed less metabolic acidosis. Hence we conclude that Plasmalyte-A is the preferred cardiopulmonary bypass prime in adult patients undergoing valve replacement surgeries.
在体外循环（CPB）期间会出现广泛的酸碱波动，代谢性酸中毒的发展是众所周知的。我们进行了一项研究，比较了乳酸林格氏液和血浆代用品-A 作为 CPB 初始液在瓣膜置换术中引起与旁路相关的酸中毒的代谢效应。
我们对 80 名接受 CPB 进行瓣膜心脏手术的成年患者进行了前瞻性、随机对照研究。患者随机分为两组：I 组（乳酸林格氏液）和 II 组（血浆代用品-A）。在启动 CPB 之前、CPB 开始后 30 分钟、之后每半小时直至 CPB 结束以及术后在 ICU 中停留半小时后，采集动脉血样以分析主要氢离子、碳酸氢盐、乳酸和强离子差。
结果以定量方式进行分析。在乳酸林格氏液组中，CPB 期间 pH 值从 T1 时的 7.428 ± 0.029 降至 7.335 ± 0.06（P < 0.01）和 T2 和 T3 时的 7.358 ± 0.06（P < 0.01）。CPB 期间乳酸林格氏液组的平均碳酸氢盐浓度从 T1 时的 24.28 ± 1.65 mEq/L 降至 T2 时的 20.98 ± 2.97 mEq/L（P < 0.01）。在血浆代用品-A 组中，所有时间点的平均 pH 值、碳酸氢盐和强离子差（SID）均无差异（P > 0.05）。在乳酸林格氏液组中，平均血乳酸水平的最大峰值从 T1 时的 0.85 ± 0.35 mmol/L 增加到 T2 和 T3 时的 4.29 ± 1.78 mmol/L（P < 0.01）和 4.17 ± 1.28 mmol/L（P < 0.01）。在血浆代用品-A 组中未观察到这种增加。乳酸林格氏液组在 CPB 期间的平均 SID 从 T1 时的 41.102 mEq/L 降至 T2 时的 35.66 mEq/L（P = 0.033），表明存在代谢性酸中毒。乳酸林格氏液组发生低血压和心律失常的患者人数也较高，再次表明酸中毒程度较高。
血浆代用品-A 和乳酸林格氏液的不同成分对接受心脏手术的患者有不同的代谢影响。接受血浆代用品-A 作为 CPB 初始液的患者发生代谢性酸中毒的程度较低。因此，我们得出结论，血浆代用品-A 是成人瓣膜置换术患者首选的 CPB 初始液。
