Moreno-Martinez Fernando, Byrne David, Raisis Anthea, Waldmann Andreas D, Hosgood Giselle, Mosing Martina
College of Veterinary Medicine, Murdoch University, Perth, WA, Australia.
Department of Anaesthesiology and Intensive Care Medicine, Rostock University Medical Centre, Rostock, Germany.
Front Vet Sci. 2022 Jun 9;9:895268. doi: 10.3389/fvets.2022.895268. eCollection 2022.
Equine respiratory physiology might be influenced by the presence of an endotracheal tube (ETT). This experimental, randomized cross-over study aimed to compare breathing pattern (BrP) and ventilation distribution in anesthetized horses spontaneously breathing room air via ETT or facemask (MASK). Six healthy adult horses were anesthetized with total intravenous anesthesia (TIVA; xylazine, ketamine, guaiphenesin), breathing spontaneously in right lateral recumbency, and randomly assigned to ETT or MASK for 30 min, followed by the other treatment for an additional 30 min. During a second anesthesia 1 month later, the treatment order was inversed. Electrical impedance tomography (EIT) using a thoracic electrode belt, spirometry, volumetric capnography, esophageal pressure difference (ΔPoes), venous admixture, and laryngoscopy data were recorded over 2 min every 15 min. Breaths were classified as normal or alternate (sigh or ) according to the EIT impedance curve. A mixed linear model was used to test the effect of treatment on continuous outcomes. Cochran-Mantel-Haenszel analysis was used to test for associations between global BrP and treatment. Global BrP was associated with treatment ( = 0.012) with more alternate breaths during ETT. The center of ventilation right-to-left (CoV) showed more ventilation in the non-dependent lung during ETT ( = 0.025). The I:E ratio ( = 0.017) and ΔPoes ( < 0.001) were smaller, and peak expiratory flow ( = 0.009) and physiologic dead space ( = 0.034) were larger with ETT. The presence of an ETT alters BrP and shifts ventilation toward the non-dependent lung in spontaneously breathing horses anesthetized with TIVA.
气管内插管（ETT）的存在可能会影响马的呼吸生理。本实验性随机交叉研究旨在比较麻醉状态下通过ETT或面罩（MASK）自主呼吸室内空气的马匹的呼吸模式（BrP）和通气分布。六匹健康成年马采用全静脉麻醉（TIVA；赛拉嗪、氯胺酮、愈创甘油醚），右侧卧位自主呼吸，并随机分配接受ETT或MASK通气30分钟，然后再接受另一种通气方式30分钟。在1个月后的第二次麻醉期间，通气方式顺序颠倒。每隔15分钟使用胸部电极带进行2分钟的电阻抗断层扫描（EIT）、肺量计、容积式二氧化碳描记法、食管压差（ΔPoes）、静脉血掺杂和喉镜检查数据记录。根据EIT阻抗曲线将呼吸分为正常或交替呼吸（叹息或其他）。使用混合线性模型测试通气方式对连续结果的影响。采用 Cochr an-Mantel-Haenszel分析测试整体BrP与通气方式之间的关联。整体BrP与通气方式相关（P = 0.012），ETT通气时交替呼吸更多。通气中心从右向左（CoV）显示，ETT通气时非下垂肺的通气更多（P = 0.025）。ETT通气时，吸气与呼气时间比（P = 0.017）和ΔPoes（P < 0.001）较小，呼气峰值流速（P = 0.009）和生理死腔（P = 0.034）较大。在接受TIVA麻醉的自主呼吸马匹中，ETT的存在会改变BrP并使通气向非下垂肺转移。
