Purpose: Patient position and body mass index (BMI) affect intra-abdominal pressure (IAP) measured by the intra-vesical method in adults. We sought to determine effects of patient position and BMI on IAP in children because accurate measurement and interpretation of IAP are important for patient management.
Methods: Seventy-seven mechanically ventilated children (<18 years) admitted to a PICU were prospectively studied. IAP was taken with the head of the bed at 0 degrees and 30 degrees every 6 h over a 24-h period. Statistical methods included descriptives, univariate statistics to identify potential confounding variables and multivariable analysis to assess the impact of position on IAP after adjusting for the significant covariates.
Results: Seventy-seven patients had 290-paired IAP measurements. Mean IAP at 30 degrees was 10.6 +/- 4.0 compared to 8.4 +/- 4.0 at 0 degrees , which was significantly higher (p = 0.026) even after adjusting for age, gender and length. There was no correlation between IAP and actual BMI or BMI percentiles.
Conclusion: Patient position should be considered when interpreting IAP. BMI did not influence IAP measurements in children.