Low arterial oxygen is a common complication in anesthetized horses and placing the animal in reverse Trendelenburg (RT) position may treat hypoxemia. The objective of this study was to assess the arterial partial pressure of oxygen (PaO₂) in horses placed in a 5-degree RT compared to horizontal (H) position. Client-owned healthy horses (n = 60) undergoing elective surgeries were enrolled in a randomized controlled clinical study. Horses were sedated with butorphanol, an α₂-adrenoceptor agonist, ± acepromazine and induced with ketamine combined with a benzodiazepine, propofol, or guaifenesin. Anesthesia was maintained with isoflurane in oxygen with mechanical ventilation. Each group (RT and H) included 30 horses, 10 in each recumbency (dorsal, right and left lateral). Arterial blood gas analyses (aBG) were performed following arterial catheter placement then hourly. Time first-to-last aBG, changes in PaO₂, dynamic compliance (C_dyn), estimated pulmonary shunt fraction (F-shunt), and alveolar dead space to tidal volume ratio (V_D/V_T) were evaluated with a 2-way analysis of variance. Statistical significance was set at p < .05. Overall, PaO₂ increased in all groups; however no significant difference was found between recumbencies (dorsal, right and left lateral) and RT versus H in changes over time for PaO₂ (p = .064 and p = .070, respectively), C_dyn (p = .721 and p = .672, respectively), F-shunt (p = .055 and p = .054, respectively), or V_D/V_T (p = .616 and p = .064, respectively). In healthy anesthetized horses, 5-degree RT did not affect changes in PaO₂ as compared to H position.

低动脉血是麻醉马的常见并发症，将动物置于特伦德伦伯卧位（RT）倒置可能会治疗低氧血症。这项研究的目的是评估与水平（H）位置相比处于5度RT的马的动脉血氧分压（PaO ₂）。 参加择期手术的客户拥有的健康马（n = 60）被纳入一项随机对照临床研究。马用布托啡诺镇静剂，α ₂-肾上腺素受体激动剂±醋丙嗪，并与氯胺酮和苯二氮卓，丙泊酚或愈创甘油醚联合诱导。在机械通气的情况下，在氧气中使用异氟烷维持麻醉。每组（RT和H）包括30匹马，每个卧位10匹（背侧，左右侧）。放置动脉导管后每小时进行一次动脉血气分析（aBG）。从时间到倒数aBG，PaO _2的变化，动态顺应性（C _dyn），估计的肺分流分数（F-shunt）和肺泡死腔与潮气量之比（V _D / V _T）用2进行评估。方差的双向分析。统计显着性设为p  <.05。总体而言，PaO ₂所有组均增加；然而，没有显著差异recumbencies之间发现（背侧，右和左外侧）和RT对H的变化随时间的氧分压₂（p  = 0.064和p 分别= 0.070，），C _DYN（p  = 0.721和p  = 0.672，分别地），F-分流（p  = 0.055和p  = 0.054，分别地），或V _d / V _Ť（p  = 0.616和p  = 0.064，分别地）。在健康的麻醉马中，与H位置相比，5度RT不会影响PaO _2的变化。