Center for Surgical Research, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
Center for Surgical Research, University Hospital Zurich, University of Zurich, Zurich, Switzerland;, Email:
Comp Med. 2022 Aug 1;72(4):257-266. doi: 10.30802/AALAS-CM-21-000103. Epub 2022 Jul 14.
The ruminant alimentary tract and its effects on blood homeostasis complicate prolonged terminal studies conducted under general anesthesia in sheep. We therefore studied 15 healthy female white alpine sheep that were undergoing prolonged anesthesia (> 30 h) for an unrelated terminal study. In the current study, all sheep developed a decreased hematocrit and hemoglobin concentration after induction of anesthesia, which fell further, along with a significant decrease in white blood cell count, over the course of anesthesia. Sheep also showed an initial hyponatremia, a persistent hypokalemia, hypocalcemia, and a progressive hyperchloremia. A significant drop in blood pH developed over time despite normal values of blood lactate and a marked decline in partial pressure of carbon dioxide over the course of the experiment. The latter consequently reduced the efficacy of mechanical ventilation, as reflected in a reduced oxygen partial pressure. A significant increase in lactate dehydrogenase and creatinine kinase was observed. Arterial blood pressure and heart rate significantly decreased over time, but remained within normotensive and normocardic limits. Central venous pressure rose significantly over the course of anesthesia. In conclusion, prolonged anesthesia in sheep is associated with a wide range of complex physi- ologic changes. An in-depth understanding of all metabolic compensatory mechanisms and their underlying cause during prolonged anesthesia is necessary for interpreting data from the primary study, with special considerations to account for ruminant-specific physiology.
反刍动物的消化道及其对血液内环境稳定的影响，使得在绵羊全身麻醉下进行长期终末研究变得复杂。因此，我们研究了 15 只健康的雌性白色阿尔卑斯绵羊，它们正在进行与本研究无关的长期麻醉（>30 小时）。在本研究中，所有绵羊在麻醉诱导后均出现血细胞比容和血红蛋白浓度降低，随着麻醉过程的进行，白细胞计数进一步下降。绵羊还表现出初始低钠血症、持续低钾血症、低钙血症和进行性高氯血症。尽管血液乳酸值正常，二氧化碳分压在实验过程中显著下降，但血液 pH 值随着时间的推移而显著下降。后者导致机械通气的效果降低，反映在氧气分压降低。乳酸脱氢酶和肌酸激酶显著升高。动脉血压和心率随时间显著下降，但仍在正常血压和正常心率范围内。中心静脉压在麻醉过程中显著升高。总之，绵羊的长时间麻醉与广泛的复杂生理变化有关。深入了解长时间麻醉过程中所有代谢代偿机制及其潜在原因，对于解释主要研究中的数据是必要的，需要特别考虑反刍动物特有的生理学。
