[The effects of auto-triggering on patient-ventilator interaction in noninvasive mechanical ventilation during air leak].

ABSTRACT

OBJECTIVE: To study the relationship between air leak and auto-triggering in noninvasive positive pressure ventilation (NIPPV), and the effects of auto-triggering on patient-ventilators interaction. METHODS: Five different types of noninvasive ventilators, a lung simulator and 14 healthy volunteers were studied by using a quantificational air leak model and a spirometer which monitoring the pressure, flow and volume curve in the tube continuously. SPSS version 10.0 was used for statistical analysis. Data were presented as x +/- s, and means were compared with analysis of variance. RESULTS: In the study of lung simulator, the percentage of times of auto triggering in total testing times was from 24% -90% in the BiPAP mode in various ventilators. Air leaking capacity was the most crucial factor related to auto triggering (beta = 0.709, OR = 2.032). With increased air leak level, 14 volunteers all presented with auto triggering. All the volunteers' respiratory rate increased and tidal volume decreased with the increasing level of air leak. CONCLUSION: Auto-triggering occurred when air leak increased in NIPPV. The insufficient compensation of flow base line may be the cause for auto-triggering. Auto-triggering can impair patients ventilation.