Abstract
The effects of pneumoperitoneum on dynamic predictors of fluid responsiveness such as pulse pressure variation (PPV) remain uncertain. This uncertainty arises from potentially opposing physiological mechanisms that affect cardiovascular dynamics during conditions with increased intra-abdominal pressure (IAP). Deriving PPV with high precision during induction of pneumoperitoneum may provide new insights into the complex relationship between intra-abdominal pressure changes and PPV. The hypothesis was that PPV derived from a generalised additive model (PPV(GAM)) would increase with the induction of pneumoperitoneum and the associacted increase in IAP. This was a prospective, observational study in patients undergoing oesophagectomy. Before and after induction of pneumoperitoneum, haemodynamic variables including PPV and stroke volume variation (SVV) were recorded with the Hemosphere monitor. PPV(GAM) was estimated offline from the arterial blood pressure curve. A total of 34 patients were included in the final analysis. PPV(GAM) increased by a factor of 1.49 (95% CI: 1.25-1.77) as intra-abdominal pressure increased from baseline to 12 mmHg. SVV and PPV from the HemoSphere monitor increased with a factor of 1.25 (95% CI: 1.13-1.39, p < 0.001) and 1.14 (95% CI: 1.00-1.29, p = 0.048), respectively. PPV derived from a generalised additive model increased approximately 50% from the induction of pneumoperitoneum to an IAP of 12 mmHg. PPV and SVV derived from the Hemosphere monitor also increased signicantly.