Hognestad Bente Wabakken, Digranes Nora, Opsund Vigdis Groven, Espenes Arild, Haga Henning Andreas
Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway.
Department of Production Animal Clinical Sciences, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, 1433 Ås, Norway.
Animals (Basel). 2023 Jul 23;13(14):2387. doi: 10.3390/ani13142387.
Stunning by carbon dioxide (CO) inhalation is controversial because it is associated with vigorous movements and behaviours which may or may not be conscious reactions. Furthermore, it is unknown whether some behaviours might indicate the transition into unconsciousness. Our study objective was to investigate the loss of consciousness during CO stunning by linking physiological variables (in particular pH, PaO and PaCO) to the onset of observed behaviours. A total of 11 cross-bred pigs were studied. A tracheostomy tube, venous and arterial cannulae were placed under sevoflurane anaesthesia. After recovery from this, and a "wash out" period of at least 30 min, arterial blood samples were taken (and baseline values established) before 90-95% CO in medical air was administered through the tracheostomy tube. Subsequent behaviours were video-recorded and key physiological variables were evaluated using an anaesthetic monitor and the frequent sampling of arterial blood (albeit with inconsistent inter-sample intervals). After the study, behaviours were classified in an ethogram. At the onset of behaviours categorised as "vigorous movement extremities", "opisthotonos" and "agonal gasping" pH values (range) were: 6.74-7.34; 6.66-6.96 and 6.65-6.87, while PaCO (kPa) was 4.6-42.2, 24.4-51.4 and 29.1-47.6. Based upon these values, we conclude that the pigs were probably unconscious at the onset of "opisthotonos" and "agonal gasping", but some were probably conscious at the onset of "vigorous movements".
通过吸入二氧化碳（CO）使人昏迷存在争议，因为这与剧烈运动和行为有关，这些运动和行为可能是有意识的反应，也可能不是。此外，尚不清楚某些行为是否可能表明已进入无意识状态。我们的研究目的是通过将生理变量（特别是pH值、动脉血氧分压[PaO]和动脉血二氧化碳分压[PaCO]）与观察到的行为发作联系起来，研究在二氧化碳致昏过程中意识的丧失。总共对11头杂交猪进行了研究。在七氟醚麻醉下放置气管造口管、静脉和动脉插管。在此恢复后，经过至少30分钟的“洗脱”期，在通过气管造口管给予含90 - 95% CO的医用空气之前，采集动脉血样本（并确定基线值）。随后对行为进行录像，并使用麻醉监测仪和频繁采集动脉血（尽管样本间间隔不一致）来评估关键生理变量。研究结束后，将行为分类制成行为谱。在被归类为“肢体剧烈运动”、“角弓反张”和“濒死喘息”的行为发作时，pH值范围分别为：6.74 - 7.34；6.66 - 6.96和6.65 - 6.87，而动脉血二氧化碳分压（kPa）分别为4.6 - 42.2、24.4 - 51.4和29.1 - 47.6。基于这些值，我们得出结论：猪在“角弓反张”和“濒死喘息”发作时可能已失去意识，但在“肢体剧烈运动”发作时一些猪可能仍有意识。
