| Abstract: Background: Abdominal compartment syndrome can develop within 12 hours of ICU admission in high-risk (shock/trauma, burn, pancreatitis, AAA rupture) patients. The current standard of intra-abdominal pressure (IAP) measurement via the urinary catheter is labour intensive and its intermittent nature could prevent timely recognition of significant changes in IAP. We propose that continuous IAP (CIAP) can be accurately measured via the irrigation port of a three-way catheter with good agreement to the standard intermittent IAP (IIAP).
Methods: CIAP was prospectively validated by comparing to IIAP measurement in general surgical and trauma patients admitted to ICU with a previously inserted three-way urinary catheter. CIAP was measured via the irrigation port of the three-way catheter transduced to the bedside monitor as a continuous trace without intermittent clamping of the catheter. The standard IIAP measurements were performed via the urine drainage port after clamping the catheter and filling the bladder with 50 mL of 0.9% saline. Three separate paired measurements of each patients were performed in standardized circumstances to compare CIAP with IIAP. Patients’ demographics, injury severity, type of surgery, body mass index (BMI) and the paired individual IAP measurements were recorded. The paired measurements were compared using the Bland-Altman (B-A) method for comparing a new clinical measurement with an established one. Data are presented as mean +/-SEM.
Results: During a 6-month period (ending in June 2003) 25 patients with age of 61.5 +/-4 years, 66% male gender, BMI of 29.2 +/-2 kg/m2 were investigated. Six patients had vascular surgical, four elective and three urgent surgical interventions. There were 12 trauma patients with ISS of 23 +/-2. The CIAP was 14.2 +/-0.66 (range 2 - 24) mmHg and the IIAP was 14.0 +/-0.68 (range 3 – 24) mmHg. 75% of the measured pairs were exactly the same, in 21% there was 1 mmHg difference and in 4% 2 mmHg. There was no measurement difference greater than 2 mmHg. The mean difference between the CIAP and IIAP was 0.019 +/-0.05 mmHg. The B-A statistics revealed that the difference between measurements in each individual patient was between +/-1.96SD. The B-A scatter plot did not follow any patterns of typical systematic bias.
Conclusion: CIAP measurement with a three-way urinary catheter is a simple and accurate method for monitoring IAP in wide pressure ranges and should replace the current labour intensive intermittent technique.
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