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。非侵入性测定CO方法的发展为实现这一目标提供了一个潜在的解决方案。本研究采用部分二氧化碳再呼吸间接Fick技术（NICO系统）对体重9.1 ~ 13.0kg的6只七氟醚麻醉的beagle犬进行了无创CO测量，并比较NICO系统（NICO）和热稀释法（TDCO）测定的CO。通过改变麻醉深度和多巴酚丁胺的施用，在低、中、高CO值期间收集了30个配对的TDCO和NICO测量值。NICO的CO值为0.70-2.60L/min，而TDCO的CO值为0.89-4.45L/min。TDCO与NICO有良好的相关性（r=0.883, p<0.0001）。一致性和相对偏倚限分别为-1.04±0.54L/min（±56.2%）和-39.9±11.6%。总之，NICO对比格犬的TDCO具有较低的一致性。对89只大犬（体重20.0 ~ 67.6kg）手术麻醉后NICO系统进行了评价。将狗分为三组：皮肤切开前自主呼吸并维持适当的动脉血压（ABP） （SB, n=23），需要人工通气以控制呼吸抑制并维持适当的动脉血压（CV, n=52），或需要人工通气并出现低血压（hypocv, n=14）。低CV组心脏指数（CI）（62±13ml/min/kg）显著低于SB组（97±27ml/min/kg, p<0.001）和CV组（84±26ml/min/kg, p=0.004）。低血压治疗后，hypocv CI显著升高（79±19ml/min/kg, p<0.001）。综上所述，NICO系统是大犬麻醉期间无创心输出量监测的一种有效方法。我们推荐0.1 L/min/kg作为麻醉大犬心脏充足的标准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.