This study used electrical impedance tomography (EIT) measurements of regional ventilation and perfusion to elucidate the reasons for severe gas exchange impairment reported in rhinoceroses during opioid-induced immobilization. EIT values were compared to standard monitoring parameters to establish a new monitoring tool for conservational immobilisation and future treatment options. Six male white rhinoceroses were immobilized using etorphine and EIT ventilation variables, venous admixture and dead space were measured 30, 40 and 50 minutes after becoming recumbent in lateral position. Pulmonary perfusion mapping using impedance-enhanced EIT was performed at the end of the study period. The measured impedance (∆Z) by EIT was compared between pulmonary regions using mixed linear models. Measurements of regional ventilation and perfusion revealed a pronounced disproportional shift of ventilation and perfusion towards the non-dependent lung. Overall, the dependent lung was minimally ventilated and perfused, but remained aerated with minimal detectable lung collapse. Perfusion was found primarily around the hilum of the non-dependent lung and was minimal in the periphery of the non-dependent and the entire dependent lung. These shifts can explain the high amount of venous admixture and physiologic dead space found in this study. Breath holding redistributed ventilation towards dependent and ventral lung areas. The findings of this study reveal important pathophysiologic insights into the changes in lung ventilation and perfusion during immobilization of white rhinoceroses. These novel insights might induce a search for better therapeutic options and is establishing EIT as a promising monitoring tool for large animals in the field.

中文翻译：

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是什么阻碍了侧卧位固定化白犀牛（Ceratotherium simum）的肺气体交换和通气分布的变化？

这项研究使用电阻抗断层扫描（EIT）对区域通气和灌注进行测量，以阐明阿片类药物诱导的固定期间犀牛中严重气体交换障碍的原因。将EIT值与标准监测参数进行比较，以建立一种新的监测工具，用于保护性固定和将来的治疗方案。使用依托啡定和EIT通气变量固定六只雄性白犀牛，在侧卧后30、40和50分钟测量静脉混合和死腔。在研究期结束时使用阻抗增强型EIT进行肺灌注成像。使用混合线性模型比较了肺区域之间通过EIT测得的阻抗（∆Z）。局部通气和灌注的测量结果显示通气和灌注向不依赖肺部明显转移。总体而言，依赖肺的通气和灌注最少，但仍保持充气状态，可检测到的肺塌陷最少。灌注主要在非依赖肺的肺门周围发现，在非依赖肺和整个依赖肺的外围最小。这些变化可以解释本研究中发现的大量静脉混合物和生理性死腔。屏气使呼吸重新分布到依赖肺和腹肺区域。这项研究的发现揭示了固定白犀牛期间肺通气和灌注变化的重要病理生理学见解。