LEAK MEASUREMENTS IN SPONTANEOUSLY BREATHING PREMATURE NEWBORNS BY USING THE FLOW-THROUGH TECHNIQUE

A new method for measuring and correcting air leaks during lung-functi on testing in infants has been validated in vitro and in vivo by using a flow-through system that measured the inflow and outflow of a face mask. An adjustable leak was quantified by using suction flow to valid ate the accuracy of leak measurements. To validate the leak correction , the volume of a pump was measured with different air leaks (0-30%). The method developed was tested in 67 infants breathing spontaneously. There was good agreement between measured and simulated leaks (r = 0. 998, P < 0.001; 95% limits of agreement were -0.3 and 0.1%, respective ly). The volume was generally underestimated because of leaks, and the volume error was up to 94% compared with the maximum error of 5% afte r leak correction. With continuous leak measurements in vivo, there we re <4% actual leaks (median 2.6%), and we did not observe any leaks in >7% of cases. The leak correction improved the accuracy of ventilator y measurements. The monitoring of leaks is helpful for airtight placem ent of the face mask and for prevention of serious measurement errors caused by leaks.