title: A bench study of the effects of leak on ventilator performance during noninvasive ventilation.
abstract: BACKGROUND
  During noninvasive ventilation (NIV), leak around the mask may cause inadequate ventilatory support or patient-ventilator asynchrony such as auto-triggering. Some NIV ventilators may be better than others at compensating for leak.
  
  
  METHODS
  We bench studied 3 NIV ventilators  (Vision, Carina, and Trilogy100) and 2 ICU ventilators (Puritan Bennett 840 and Evita XL) to assess how they coped with 2 leak levels and zero leak during NIV. With a 2-bellows-in-a-box lung model we simulated spontaneous breathing with tidal volumes of 300 mL and 500 mL, at pressure support  of 0 and 10 cm H(2)O and PEEP of 5 and 10 cm H(2)O. We affixed the airway opening of the lung model to the mouth of a mannequin head and secured a mask on the mannequin face. We created a medium leak and a large leak with different size holes, and measured PEEP in the presence  of leak. We also measured the actual pressure-support values and calculated the deviations from the set pressure-support value and the pressure-time product (PTP) of the airway opening pressure below and above baseline.
  
  
  RESULTS
  With the medium leak only the Vision and Carina maintained the  set PEEP and pressure support. With the large leak the pressure support was decreased with all the tested ventilators. With the larger leak and pressure support of 10 cm H(2)O the PTP below baseline for triggering increased with 2 ventilators, and the PTP above baseline for supporting  the patient's inspiratory effort decreased with all 5 ventilators. The larger tidal volume increased the PTP below baseline with all 5 ventilators and at all leak sizes.
  
  
  CONCLUSIONS
  Some of the ventilators compensated for leak better than others. With the larger leak none of the ventilators  maintained the set PEEP or pressure support.
authors: Department of Emergency and Critical Care Medicine, University of Tokushima Graduate School, Tokushima, Japan.
authors: Yoshitoyo
authors: Y
authors: Ueno
authors: Nobuto
authors: N
authors: Nakanishi
authors: Jun
authors: J
authors: Oto
authors: Hideaki
authors: H
authors: Imanaka
authors: Masaji
authors: M
authors: Nishimura