Introduction: Bladder pressure is routinely measured in the clinical setting to estimate intra-abdominal pressure (IAP). Elevated IAP also affects standard airway pressure measurements. In a porcine model of controlled intra-abdominal hypertension (IAH), we evaluated the fidelity of the standardized bladder pressure measurement and airway plateau pressure changes over a range of IAPs. Methods: Eight (n=8) deeply anesthetized swine were mechanically ventilated at VT=10 ml/kg, f=15, I:E=1:2 and PEEP=1 and 10 cmH2O. After surgical placement of airway tubing in the peritoneal cavity, different levels of IAP (5, 10, 15, 20 and 25 mmHg) were applied via a CPAP system. Bladder pressure and airway pressure were each measured after 10 minutes of stabilization at each level of IAP and during PEEP= 1 and 10 cmH2O. Results: Bladder pressure changed in parallel with IAP. When IAP is >10 mmHg, a mean underestimation of 3.25卤0.83 mmHg was observed. Airway plateau pressure also increased with IAP. Bladder pressure was not affected by PEEP (1 and 10 mmHg) or the ventilatory cycle in this air-based model. Conclusion: Our model confirms the reported role of bladder pressure measurement in identifying IAH. Minimal underestimation is noted (3-4 mmHg after IAP>10 mmHg); probably due to incomplete pressure transmission. During mechanical ventilation, airway plateau pressure is directly influenced by IAP as estimated by bladder pressure.
