Development and clinical application of non-invasive cardiac output measurement in dogs and cats

维持最佳心输出量（CO）是术中血流动力学管理的重要目标。用于确定CO的非侵入性方法的发展为这一目标提供了潜在的解决方案。本研究对部分二氧化碳再吸入间接Fick法（NICO系统）进行了无创CO测定的评价，并对6只Beagle犬（体重9.1-13.0kg）在七氟醚麻醉下，用NICO系统（NICO系统）和热稀释法（TDCO）测定CO进行了比较。通过改变麻醉深度和多巴酚丁胺的给药，在CO的低、中和高值期间收集30对TDCO和NICO的测量值。NICO的CO值范围为0.70- 2.60 L/min，TDCO为0.89- 4.45 L/min。TDCO与NICO有良好的相关性（r=0.883，p<0.0001）。一致性和相对偏差的极限分别为-1.04 0. 54 L/min（±56.2%）和-39.9 11. 6%。总之，NICO在Beagle犬中提供的与TDCO的一致性较低。实验犬分为3组：切皮前自主呼吸并维持足够的动脉血压（SB，n=23），需要人工通气控制呼吸抑制并维持足够的动脉血压（CV，n=52），或需要人工通气并显示低血压（Hypo-CV，n=14）。心指数（CI）在Hypo-CV组（62± 13 ml/min/kg）显著低于SB组（97± 27 ml/min/kg，p<0.001）和CV组（84± 26 ml/min/kg，p=0.004）。低血压治疗后Hypo-CV的CI显著增加（79± 19 ml/min/kg，p<0.001）。CI的变化与ABP的变化一致。总之，NICO系统是一种无创监测大型犬麻醉期间心输出量的有效方法。我们建议将0.1 L/min/kg的值作为麻醉大型犬心脏充足的标准NICO值。

Maintaining optimal cardiac output (CO) is an important goal of intraoperative hemodynamic management. The development of non-invasive methods for determining CO provides a potential solution to this goal. In this study, partial carbon dioxide rebreathing indirect Fick technique (NICO system) was evaluated for non-invasive CO measurementCO determined using NICO system (NICO) and thermodilution (TDCO) were compared in sevoflurane anesthetized 6 beagle dogs (body weight : 9.1-13.0kg). Thirty paired measurements of TDCO and NICO were collected during low, intermediate, and high values of CO achieved by varying the depth of anesthesia and the administration of dobutamine. The CO values ranged from 0.70-2.60L/min for NICO compared to 0.89-4.45L/min for TDCO. There was good correlation between TDCO and NICO (r=0.883, p<0.0001). The limits of agreement and relative bias were -1.04±0.54L/min (±56.2%) and -39.9±11.6%. In conclusion, NICO provided a low agreement to TDCO in beagle dogs.NICO system was evaluated in 89 large-breed dogs (body weight : 20.0-67.6kg) anesthetized for surgery. The dogs were classified into three groups : breathed spontaneously and maintained adequate arterial blood pressure (ABP) before skin incision (SB, n=23), required artificial ventilation to control respiratory depression and maintained adequate ABP (CV, n=52), or required artificial ventilation and showed hypotension (Hypo-CV, n=14). Cardiac index (CI) in Hypo-CV (62±13ml/min/kg) were significantly lower than SB (97±27ml/min/kg, p<0.001) and CV (84±26ml/min/kg, p=0.004). The CI in Hypo-CV increased significantly after the treatment for hypotension (79±19ml/min/kg, p<0.001). Changes in CI agreed with changes in ABP. In conclusion, NICO system is a useful method for non-invasive cardiac output monitoring during anesthesia in large-breed dogs. We recommend the value of 0.1 L/min/kg as a standard NICO value for adequate cardiac in anesthetized large-breed dogs.