THE ACCURACY OF THE FLOW-RATE IN FLUSH-DEVICES OF DISPOSABLE PRESSURETRANSDUCERS

Background: Arterial and venous pressure is commonly measured using fl uid filled catheters. To avoid obstruction they are continuously spill ed by a flush-device. The accuracy of the flowrate has not been invest igated previously. Methods: The accuracy of 5 different flush-devices available in Switzerland was checked for flowrate when factory new, af ter a single sterilization with ethylen-oxide, in a long-term test ove r 96 hours, after repeated handling of the integrated bypass and under application of a pulsing counter-pressure. Results: Flow is linearly related to differential-pressure and is constant over time. The flow o f each flush-device at 200 mmHg differential-pressure was below the in dicated 3 ml per hour (1.69 - 2.49 ml / h). Sterilization in two types produced a significant but not relevant difference in flowrate. Longt ime-use, bypass actuation and pulsing pressure did not alter the flowr ate significantly (p<0.05). In two factory-new flush-devices and 4 re- used ones a plugged capillary induced cessation of flow. Conclusions: Flowrate in flush-devices is accurate under sterilization, longtime us e, bypass-actuation and pulsing counter pressure. A plugged capillary occurred in a few new and reused flush-devices, which can be the expla nation for clotted catheters in clinical use.