Modeling intra-abdominal volume and respiratory driving pressure during pneumoperitoneum insufflation-a patient-level data meta-analysis

During pneumoperitoneum, intra-abdominal pressure (IAP) is usually kept at 12–14 mmHg. There is no clinical benefit in IAP increments if they do not increase intra-abdominal volume IAV. We aimed to estimate IAV (DIAV) and respiratory driving pressure changes (DP _RS) in relation to changes in IAP (DIAP). We carried out a patient-level meta-analysis of 204 adult patients with available data on IAV and DP _RS during pneumoperitoneum from three trials assessing the effect of IAP on postoperative recovery and airway pressure during laparoscopic surgery under general anesthesia. The primary endpoint was DIAV, and the secondary endpoint was DP _RS. The endpoints’ response to DIAP was modeled using mixed multivariable Bayesian regression to estimate which mathematical function best fitted it. IAP values on the pressure–volume (PV) curve where the endpoint rate of change according to IAP decreased were identified. Abdomino-thoracic transmission (ATT) rate, that is, the rate DP _RS change to DIAP was also estimated. The best-fitting function was sigmoid logistic and linear for IAV and DP _RS response, respectively. Increments in IAV reached a plateau at 6.0 [95%CI 5.9–6.2] L. DIAV for each DIAP decreased at IAP ranging from 9.8 [95%CI 9.7–9.9] to 12.2 [12.0–12.3] mmHg. ATT rate was 0.65 [95%CI 0.62–0.68]. One mmHg of IAP raised DP _RS 0.88 cmH ₂O. During pneumoperitoneum, IAP has a nonlinear relationship with IAV and a linear one with DP _RS. IAP should be set below the point where IAV gains diminish. NEW & NOTEWORTHY We found that intra-abdominal volume changes related to intra-abdominal pressure increase reached a plateau with diminishing gains in commonly used pneumoperitoneum pressure ranges. We also found a linear relationship between intra-abdominal pressure and respiratory driving pressure, a known marker of postoperative pulmonary complications.