Evaluation of a modified piezoresistive technique and a water-capsule technique for direct and continuous measurement of intra-abdominal pressure in a porcine model.
OBJECTIVE
Intravesical pressure measurement is considered to be the gold standard for the assessment of intra-abdominal pressure. However, this method is indirect and depends on a physiologic bladder function. We evaluated a modified piezoresistive technique and a water-capsule technique for direct and continuous intra-abdominal pressure measurement.


METHODS
Experimental study.


METHODS
Animal research laboratory.


METHODS
Eleven male domestic pigs.


METHODS
In anesthetized and mechanically ventilated animals, CO2 was insufflated to stepwise increase the intra-abdominal pressure to 30 mm Hg. Pressure was then held constant for 9 hrs followed by decompression. Piezoresistive measurement and water-capsule measurement probes were placed intra-abdominally.


RESULTS
Readings of intravesical pressure measurement, piezoresistive measurement, and water-capsule measurement were taken hourly. Mean difference to insufflator readings, confidence intervals, and limits of agreement were calculated. Differences between applied pressure and intra-abdominal pressure readings were assessed using a two-factor analysis of variance. No significant differences between methods could be observed. During stepwise pressure increase, limits of agreements were -3.6 to 3.6 mm Hg. Confidence intervals were -3.4 to 3.5 (intravesical pressure measurement), -1.6 to 1.5 (piezoresistive measurement), and 0.5 to 2.9 mm Hg (water-capsule measurement). In the presence of constantly elevated intra-abdominal pressure, limits of agreement ranged from -8.2 to +8.2 mm Hg. Confidence intervals were -0.4 to 6.2 (intravesical pressure measurement), -0.2 to 2.7 (piezoresistive measurement), and 1.1 to 5.1 mm Hg (water-capsule measurement).


CONCLUSIONS
Both piezoresistive measurement and water-capsule measurement had smaller confidence intervals than intravesical pressure measurement, indicating higher precision, whereas water-capsule measurement had a significant offset. Piezoresistive measurement could be the most suitable device for continuous direct intra-abdominal pressure monitoring in specific patients.
Schachtrupp
Alexander
A
Department of Surgery, Technical University of Aachen, and Department, of Visceral and Thoracic Surgery, Central Hospital of the German Armed Forces, Koblenz, Germany.
Henzler
Dietrich
D
Orfao
Sandra
S
Schaefer
Werner
W
Schwab
Robert
R
Becker
Peter
P
Schumpelick
Volker
V
D000005:Abdomen; D000704:Analysis of Variance; D000818:Animals; D003161:Compartment Syndromes / Q000175:diagnosis*; D016001:Confidence Intervals; D008297:Male; D008365:Manometry / Q000295:instrumentation*; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D015203:Reproducibility of Results; D013552:Swine; D014160:Transducers, Pressure