title: Performance of noninvasive ventilation modes on ICU ventilators during pressure support: a bench model study.
abstract: OBJECTIVE
  Noninvasive ventilation (NIV) is often applied with ICU ventilators. However, leaks at the patient-ventilator interface interfere with several key ventilator functions. Many ICU ventilators feature an NIV-specific mode dedicated to preventing these problems. The present bench model study aimed to evaluate the performance of these modes.
  
  
  METHODS
  Bench model study in an intensive care research laboratory of a university hospital.
  
  
  METHODS
  Eight ICU ventilators, widely available in Europe and featuring an NIV mode, were connected by an NIV mask to a lung model featuring a plastic head to mimic NIV conditions, driven by an ICU ventilator imitating patient effort. Tests were conducted in the absence and presence of leaks, the latter condition with and without activation of the NIV mode. Trigger delay, trigger-associated inspiratory workload, and pressurization were tested in conditions of normal respiratory mechanics, and cycling was also assessed in obstructive and restrictive conditions.
  
  
  RESULTS
  On most ventilators leaks led to an increase in trigger delay and workload, a decrease in pressurization, and delayed cycling. On most ventilators the NIV mode partly or totally corrected these problems, but with large variations between machines. Furthermore, on some ventilators the NIV mode worsened the leak-induced dysfunction.
  
  
  CONCLUSIONS
  The results of this bench-model NIV study confirm that leaks interfere with several key functions of ICU ventilators. Overall, NIV modes can correct part or all of this interference, but with wide variations between machines in terms of efficiency. Clinicians should be aware of these differences when applying NIV with an ICU ventilator.
authors.affiliation: Intensive Care, University Hospital, 1211 Geneva 14, Switzerland. laurence.vignaux@hcuge.ch
authors.forename: Laurence
authors.initials: L
authors.lastname: Vignaux
authors.forename: Didier
authors.initials: D
authors.lastname: Tassaux
authors.forename: Philippe
authors.initials: P
authors.lastname: Jolliet
mesh_terms: D004867:Equipment Design; D004868:Equipment Failure; D019544:Equipment Failure Analysis; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D012121:Respiration, Artificial / Q000295:instrumentation* / Q000592:standards; D013557:Switzerland