Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
Vet Anaesth Analg. 2023 Jan;50(1):72-80. doi: 10.1016/j.vaa.2022.10.002. Epub 2022 Oct 26.
To compare cardiopulmonary variables and blood gas analytes in guinea pigs (Cavia porcellus) during anesthesia with and without abdominal carbon dioxide (CO) insufflation at intra-abdominal pressures (IAPs) 4 and 6 mmHg, with and without endotracheal intubation.
Prospective experimental trial.
A total of six intact female Hartley guinea pigs.
A crossover study with sequence randomization for IAP and intubation status was used. The animals were sedated with intramuscular midazolam (1.5 mg kg) and buprenorphine (0.2 mg kg) and anesthetized with isoflurane, and an abdominal catheter was inserted for CO insufflation. Animals with endotracheal intubation were mechanically ventilated and animals maintained using a facemask breathed spontaneously. After 15 minutes of insufflation, the following variables were obtained at each IAP: pulse rate, respiratory rate, rectal temperature, oxygen saturation, end-tidal CO (intubated only), peak inspiratory pressure (intubated only), noninvasive blood pressure and blood gas and electrolyte values, with a rest period of 5 minutes between consecutive IAPs. After 4 weeks, the procedure was repeated with the guinea pigs assigned the opposite intubation status.
Intubated guinea pigs had significantly higher pH and lower partial pressure of CO in cranial vena cava blood (PvCO) than nonintubated guinea pigs. An IAP of 6 mmHg resulted in a significantly higher PvCO (65.9 ± 19.0 mmHg; 8.8 ± 2.5 kPa) than at 0 (53.2 ± 17.2 mmHg; 7.1 ± 2.3 kPa) and 4 mmHg (52.6 ± 10.8 mmHg; 7.01 ± 1.4 kPa), mean ± standard deviation, with intubated and nonintubated animals combined.
Although the oral anatomy of guinea pigs makes endotracheal intubation difficult, capnoperitoneum during anesthesia induces marked hypercapnia in the absence of mechanical ventilation. An IAP of 4 mmHg should be further evaluated for laparoscopic procedures in guinea pigs because hypercapnia may be less severe than with 6 mmHg.
比较在腹腔内压力（IAP）为 4mmHg 和 6mmHg 时，有无气管内插管，有无腹部二氧化碳（CO）充气对豚鼠麻醉时心肺变量和血气分析的影响。
前瞻性实验研究。
总共 6 只完整的雌性 Hartley 豚鼠。
采用 IAP 和插管状态的交叉研究和序列随机化。动物经肌内注射咪达唑仑（1.5mg/kg）和布比卡因（0.2mg/kg）镇静，并用异氟烷麻醉，并插入腹部导管进行 CO 充气。气管内插管的动物接受机械通气，而使用面罩的动物则自主呼吸。充气 15 分钟后，在每个 IAP 下获得以下变量：脉搏率、呼吸率、直肠温度、氧饱和度、呼气末 CO（仅插管）、吸气峰压（仅插管）、无创血压和血气电解质值，连续 IAP 之间有 5 分钟的休息期。4 周后，对豚鼠进行相反的插管状态分配，重复该程序。
气管内插管的豚鼠颈内静脉血的 pH 值明显较高，二氧化碳分压（PvCO）明显较低。IAP 为 6mmHg 时，PvCO 明显高于 0mmHg（53.2±17.2mmHg；7.1±2.3kPa）和 4mmHg（52.6±10.8mmHg；7.01±1.4kPa），合并气管内插管和非气管内插管的动物。
尽管豚鼠的口腔解剖结构使气管内插管困难，但在没有机械通气的情况下，麻醉期间的腹腔积气会导致明显的高碳酸血症。对于豚鼠的腹腔镜手术，应进一步评估 4mmHg 的 IAP，因为与 6mmHg 相比，高碳酸血症可能不太严重。
