• Manel Luján, Ana Sogo, Carles Grimau, Xavier Pomares, Lluís Blanch, and Eduard Monsó.
• Servei de Pneumologia, Corporaciò Sanitària Parc Taulí, Hospital de Sabadell, Universitat Autònoma de Barcelona, Parc Taulí, Sabadell Centro de Investigación Biomédica en Red Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid mlujan@tauli.cat.
• Respir Care. 2015 Feb 1; 60 (2): 191-200.

IntroductionThe effect of leaks on volume-targeted pressure support noninvasive ventilation mode has only been tested with continuous simulated leaks. The objective of the study was to assess the influence of random leaks occurring either during inspiration or expiration.MethodsAnalysis of the volume-targeted pressure support mode in 6 commercial ventilators with single-limb circuits and intentional leak in a bench study (restrictive model). Unintentional leaks were introduced through a mechanical system during inspiration (threshold valve with 2 levels of leaks) or during expiration (active valve). Results of delivered tidal volume (VT) and pressure support were externally recorded. A pre-set VT of 550 mL was programmed, with a wide range of pressure support values.ResultsAll the ventilators showed a deviation of delivered versus programmed VT below 10% in the period without unintentional leaks. In the model with unintentional inspiratory leaks, a progressive drop in delivered VT and pressure support was observed for all ventilators. The reduction in the delivered VT for the highest inspiratory leak ranged between 21 and 40%, corresponding to a decrease in pressure support between 3.09 and 10.15 cm H2O after 5 min. Conversely, in the expiratory model, increases in delivered VT and pressure support were observed, ranging between 16 and 33% and between 2.7 and 6.5 cm H2O, respectively.ConclusionsThe introduction of random leaks influences the performance of commercial ventilators with single-limb circuits and intentional leak. The decrease in delivered VT with inspiratory leaks reaches a magnitude that may have clinically important impacts.Copyright © 2015 by Daedalus Enterprises.

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