Direct measurement of intra-abdominal pressure in various conditions

Objective: To standardise a direct method for measuring intra-abdominal pressure (IAP), to correlate the results with intrarectal pressure, and to compare the results in various conditions. Design: Prospective open study. Setting: Teaching hospital, Egypt. Subjects: 34 Subjects in 4 groups: control (n = 11), hernia (n = 8; 6 umbilical and incisional), mass (n = 7; 6 enlarged spleen and 1 carcinoma of sigmoid), and obese (n = 8; a mean of 40% above expected weight). Interventions: Measurement of IAP with a Verres needle connected to a pressure transducer with the patient at rest, straining, supine, erect, and before and after anaesthesia. Intrarectal pressure was measured simultaneously. Main outcome measures: Reproducibility and correlation between the two measurements. Results: The hernia group had significantly lower IAP than controls both at rest and on straining (mean (SD) 2.7 (1.5) cm H·O compared with 7.0 (5.09) and 6.1 (2.7) compared with 20.5 (7.9), p < 0.01 in each case). Neither the mass nor the obese group differed from the controls at rest, but the pressure was higher on straining (31.2 (1.4) and 33.5 (2.07) cm H₂O, respectively, compared with 21.9 (7.3), p < 0.05 in each case). There was a significant drop in IAP after anaesthesia in all groups, and no significant difference between intrarectal pressure and IAP in any group. Conclusion: The method of measuring IAP is reproducible. Intrarectal pressure is similar to IAP and can therefore be used instead of it.