Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, USA.
Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA.
Vet Anaesth Analg. 2022 Jul;49(4):372-381. doi: 10.1016/j.vaa.2022.04.002. Epub 2022 Apr 15.
To compare the cardiopulmonary effects of apneustic anesthesia ventilation (AAV) and conventional mechanical ventilation (CMV) in dorsally recumbent anesthetized horses.
Randomized, crossover design.
A total of 10 healthy adult horses from a university-owned herd.
Following xylazine, midazolam and ketamine administration, horses were orotracheally intubated and positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen [inspired oxygen fraction (FiO) = 0.3 initially, with subsequent titration to maintain PaO ≥ 85 mmHg (11.3 kPa)]. Horses were instrumented and ventilated with AAV or CMV for 1 hour according to predefined criteria [10 mL kg tidal volume (V), PaCO of 40-45 mmHg (5.3-6.0 kPa) during CMV and <60 mmHg (8.0 kPa) during AAV]. Dobutamine was administered to maintain mean arterial pressure (MAP) >65 mmHg. Cardiopulmonary data were collected at baseline, 30 and 60 minutes. The effects of ventilation mode and time were analyzed using repeated-measures anova with significance defined as p < 0.05.
Data from nine horses were analyzed. A significant effect of mode at one or more time points was found for respiratory rate, arterial and end-tidal CO tensions, arterial pH, mean airway pressure (P), respiratory system dynamic compliance index (CI), venous admixture (Q˙/Q˙), mean pulmonary artery pressure and systemic vascular resistance. No significant differences between modes were found for V, FiO, PaO, arterial hemoglobin saturation, alveolar dead space, heart rate, MAP, cardiac index, stroke volume index, oxygen delivery index, oxygen extraction ratio and dobutamine administration.
In dorsally recumbent anesthetized horses, both ventilation modes supported adequate oxygenation with minimal supplemental oxygen. Compared with CMV, AAV resulted in higher CI and lower Q˙/Q˙. Despite higher mean P with AAV, the cardiovascular effects of each mode were not different. Further trials of AAV in anesthetized horses are warranted.
比较仰卧位麻醉马的呼吸暂停通气（AAV）和常规机械通气（CMV）的心肺效应。
随机交叉设计。
来自大学拥有的畜群的总共 10 匹健康成年马。
在马被二甲苯胺、咪达唑仑和氯胺酮给药后，它们经口气管内插管并置于仰卧位。异氟醚在氧气中维持麻醉[初始吸入氧气分数（FiO）为 0.3，随后滴定以维持 PaO≥85mmHg（11.3kPa）]。根据预设标准，马通过 AAV 或 CMV 通气 1 小时[10mLkg潮气量（V），CMV 期间 PaCO为 40-45mmHg（5.3-6.0kPa），AAV 期间<60mmHg（8.0kPa）]。给予多巴酚丁胺以维持平均动脉压（MAP）>65mmHg。在基线、30 和 60 分钟时收集心肺数据。使用重复测量方差分析分析通气模式和时间的影响，定义显著性为 p<0.05。
分析了 9 匹马的数据。在一个或多个时间点发现模式有显著影响，包括呼吸频率、动脉和呼气末 CO 张力、动脉 pH、平均气道压力（P）、呼吸系统动态顺应性指数（CI）、静脉混合（Q˙/Q˙）、肺动脉平均压和全身血管阻力。两种模式之间在 V、FiO、PaO、动脉血红蛋白饱和度、肺泡死腔、心率、MAP、心指数、每搏量指数、氧输送指数、氧提取比和多巴酚丁胺给药方面无显著差异。
在仰卧位麻醉的马中，两种通气模式均支持充足的氧合，仅需最小量的补充氧气。与 CMV 相比，AAV 导致更高的 CI 和更低的 Q˙/Q˙。尽管 AAV 的平均 P 较高，但两种模式的心血管效应无差异。需要进一步在麻醉马中进行 AAV 的试验。
