Evaluation of the Spiegelberg method and the bladder method with different intravesical volumes for measurement of intra-abdominal pressure in a porcine model of intra-abdominal hypertension

Background

Measurement of intravesical pressure (IVP) is generally accepted as the gold standard for indirect, intermittent assessment of intra-abdominal pressure (IAP). However, data about bladder priming volumes are not uniform: 50–100 ml is considered adequate but little is known about smaller volumes (10–15 ml) to prevent falsely high pressures in less compliant bladders. This study compared bladder pressure measurements with different priming volumes for assessment of IAP in a porcine model of intra-abdominal hypertension (IAH). In addition, we compared the Spiegelberg method for direct, continuous intra-peritoneal assessment of IAP versus the intermittent IVP method.

Methods

We studied five anesthetized and ventilated pigs (46 ± 3 kg) in the prone position after insertion of a suprapubic bladder catheter and an intraperitoneal pressure catheter (Spiegelberg, Hamburg). We measured IVP with increasing priming volumes (10, 20, 30, 40, 50 ml) at four different IAP levels (baseline, 10, 20, 30 mmHg during 45 min each) achieved by infusing warmed saline into the peritoneal cavity. Pressure-volume (PV) bladder curves were constructed for each IAP level. Simultaneously, the Spiegel-berg pressure (SP) was recorded. The mean difference (bias) between IVP and SP measurements and the limits of agreement were calculated according to the method of Bland-Altman.

Results

Bias for SP as compared with IVP was maximally 0.9 ± 1.9 mmHg (Table 1). Limits of agreement between SP and IVP (over all IAP levels) were better for lower priming volumes. Bladder PV curves showed no significant difference for different priming volumes (at all IAP levels). However, at an IAP of 25 mmHg, as an example of a critical IAP in clinical practice, the range of IVP values was 20.1–29.9 mmHg, even with 10 ml as the preferred distending volume.

Table 1

Conclusion

In this model of porcine IAH, measurement of IAP was not significantly influenced by priming volumes between 10 and 50 ml. The classical IVP measurement demonstrated good agreement with the Spiegelberg method.