UC Davis

The objective of this study was to evaluate the effect of intra-abdominal pressure (IAP) on cardiorespiratory parameters during pneumoperitoneum with carbon dioxide in domestic rabbits. Six juvenile female New Zealand white rabbits were assigned to randomized sequences of IAP (0, 4, 8 mmHg) in a crossover study. The following parameters were measured at each IAP: direct arterial blood pressure (ABP); cardiac output, (CO), cardiac index, and stroke volume index (CI, SVI); heart rate; end-tidal carbon dioxide (ETCO₂); arterial blood gases (PaCO₂, PaO₂); peak inspiratory pressure (PIP); and peripheral oxygen saturation (SpO₂). Between IAPs, the abdomen was desufflated for a 5-minute washout period. Mixed linear regression models were used for statistical analysis. Heart rate, SpO₂, and ABP were not significantly affected by IAP, although there was a positive increase in ABP with IAP. Partial pressure of carbon dioxide (PaCO₂) was increased at an IAP of 8 mmHg and ETCO₂ and PIP were greater with each IAP applied. Cardiac output and CI were significantly decreased with IAP and, although SVI showed the same trend, it was not statistically significant. In conclusion, pneumoperitoneum with carbon dioxide causes an increase in ETCO₂, PaCO₂, and PIP, whereas cardiac output and CI decrease. These cardiorespiratory changes should be considered when determining the optimal IAP for laparoscopic procedures in rabbits.