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Clogging of drainage catheters: quantitative and longitudinal assessment by monitoring intracatheter pressure in catheters and rabbits.

PURPOSE
To develop a method for the quantitative and longitudinal assessment of clogging in drainage catheters and to confirm the validity of the method.


MATERIALS AND METHODS
Intracatheter pressure was measured during the infusion of saline at a rate of 0.1-3.0 mL/sec in nine catheters with different internal diameters. With the data obtained, a fitting equation between the intracatheter pressure and internal diameter was derived on the basis of the Poiseuille law. To confirm the validity of this measurement method, four drainage catheters were inserted into the peritoneal cavity in each of 15 rabbits. Intracatheter pressures at infusion rates of 0.1 and 0.5 mL/sec were monitored for 14 days, while the degrees of catheter clogging were graded on the basis of the different frequencies of manual irrigation: one, two, or three times per day. Repeated measures analysis of variance was used to determine the statistical significance of differences in pressure between different irrigation frequencies.


RESULTS
Pressure was measured successfully throughout the experiment except in three rabbits with dislodged catheters. Three to 14 days after catheter insertion, the pressures were significantly lower in catheters with higher irrigation frequencies than in those with lower irrigation frequencies (P <.05). The effective internal diameter of each catheter could be monitored by means of the derived fitting equation.


CONCLUSION
This method can be used to quantitatively measure the degree of clogging of a drainage catheter. It can also be used for comparative or longitudinal in vivo studies concerning the effectiveness of drainage procedures or catheter development.