Niyom Sirirat, Mama Khursheed R, King Melissa, Contino Erin, Ferris Dora, Valdes-Martinez Alex, Frisbie David D, McIlwraith Wayne, Zumbrunnen James
Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University, Bangkok 10900, Thailand.
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, U.S.A.
J Vet Med Sci. 2018 Nov 1;80(10):1584-1589. doi: 10.1292/jvms.18-0032. Epub 2018 Sep 3.
This study investigated the influence of changing recumbency and mode of ventilation over repeated anesthesias on the alveolar to arterial oxygen tension gradient (PO) and laboratory analytes in eight horses during a year-long imaging study. Anesthesia was induced with xylazine, diazepam or guaifenesin, and ketamine and maintained with isoflurane. Horses were positioned in right or left lateral recumbency for computed tomography. Ventilation was controlled during 47% of the anesthetics. Blood was sampled from an arterial catheter prior to (30 ± 5 min from connection to anesthetic circuit), within 5 min of changing lateral recumbency, and prior to circuit disconnection (24 ± 6 min after second sample) for measurement of pH, partial pressure of arterial oxygen (PaO) and partial pressure of arterial carbon dioxide, blood glucose and electrolytes. PO was calculated. Data from five anesthetic episodes for each horse were summarized as mean ± standard error and analyzed using a mixed-model ANOVA. t tests were used for pairwise comparisons (P<0.05). PaO decreased after turning (198 vs. 347 mmHg), then increased to 291 mmHg prior to disconnection. Correspondingly, PO was wider (252 vs.120 mmHg), and improved before disconnection (190 mmHg). Body temperature, ionized-Ca and blood glucose were lower, and Na was higher at the last time point. In conclusion, turning anesthetized horses decreases PaO and results in a widening PO suggesting a cautious approach in animals with pre-existing hypoxemia.
在一项为期一年的影像学研究中，本研究调查了八匹马在重复麻醉过程中改变卧位和通气模式对肺泡-动脉氧分压差（PO）及实验室分析指标的影响。使用赛拉嗪、地西泮或愈创甘油醚以及氯胺酮诱导麻醉，并用异氟烷维持麻醉。马匹在计算机断层扫描时采取右侧或左侧卧位。47%的麻醉过程中控制通气。在连接麻醉回路后30±5分钟、改变侧卧体位后5分钟内以及断开回路前（第二次采样后24±6分钟）从动脉导管采集血液，用于测量pH值、动脉血氧分压（PaO）、动脉血二氧化碳分压、血糖和电解质。计算PO。每匹马五次麻醉事件的数据总结为平均值±标准误差，并使用混合模型方差分析进行分析。采用t检验进行两两比较（P<0.05）。翻身（侧卧体位改变）后PaO下降（198对347 mmHg），然后在断开回路前升至291 mmHg。相应地，PO增大（252对120 mmHg），并在断开回路前有所改善（190 mmHg）。在最后一个时间点，体温、离子钙和血糖较低而钠较高。总之，翻转麻醉马匹会降低PaO并导致PO增大，提示对已有低氧血症的动物应谨慎处理。
