In late years, cases of NPPV (non-invasive positive pressure ventilation therapy) increased. Because we do not need intubation by the breathing management of NPPV, a wearing state to the patient of the NPPV mask is important, and has a big influence on curative effect. In this study, we built the system that measured quantity of leak by the state of the fitting for the mask, and measured the mask internal pressure under the situation that there was leak. This system measured the state of the fitting and the quantity of leak from a mask, and mask internal pressure with a face model.

We measured quantity of leak in four ways of wearing state about two kinds of masks, but all became the leak rate more than 80%. In addition, the mask internal pressure was shown to maintain positive pressure set in a respirator even if leak existed. Although we were apt to strongly do a fitting because we were afraid of the leak from a mask, we knew that the mask internal pressure could maintain a set point even if leak existed, and the leak did not decrease even if we strongly did a fitting.