Some cardiopulmonary effects of capnoperitoneum in anesthetized guinea pigs (Cavia porcellus): spontaneous ventilation versus intubation and mechanical ventilation.

Julianne E McCready, Andrea Sanchez, Tainor Tisotti, Hugues Beaufrère

Veterinary anaesthesia and analgesia 2023 Jan

filter terms:

To compare cardiopulmonary variables and blood gas analytes in guinea pigs (Cavia porcellus) during anesthesia with and without abdominal carbon dioxide (CO2) 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-1) and buprenorphine (0.2 mg kg-1) and anesthetized with isoflurane, and an abdominal catheter was inserted for CO2 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 CO2 (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 CO2 in cranial vena cava blood (PvCO2) than nonintubated guinea pigs. An IAP of 6 mmHg resulted in a significantly higher PvCO2 (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. Copyright © 2022 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Citation

Julianne E McCready, Andrea Sanchez, Tainor Tisotti, Hugues Beaufrère. Some cardiopulmonary effects of capnoperitoneum in anesthetized guinea pigs (Cavia porcellus): spontaneous ventilation versus intubation and mechanical ventilation. Veterinary anaesthesia and analgesia. 2023 Jan;50(1):72-80