title: Patient ventilator asynchrony in critically ill adults: frequency and types.
abstract: BACKGROUND
  Patient ventilator asynchrony (PVA) occurs frequently, but little is known about the types and frequency of PVA. Asynchrony is associated with significant patient discomfort, distress and poor clinical outcomes (duration of mechanical ventilation, intensive care unit and hospital stay).
  
  
  METHODS
  Pressure-time and flow-time waveform data were collected on 27 ICU patients using the Noninvasive Cardiac Output monitor for up to 90 min per subject and blinded waveform analysis was performed.
  
  
  RESULTS
  PVA occurred during all phases of ventilated breaths and all modes of ventilation. The most common type of PVA was Ineffective Trigger. Ineffective trigger occurs when the patient's own breath effort will not trigger a ventilator breath. The overall frequency of asynchronous breaths in the sample was 23%, however 93% of the sample experienced at least one incident of PVA during their observation period. Seventy-seven percent of subjects experienced multiple types of PVA.
  
  
  CONCLUSIONS
  PVA occurs frequently in a variety of types although the majority of PVA is ineffective trigger. The study uncovered previously unidentified waveforms that may indicate that there is a greater range of PVAs than previously reported. Newly described PVA, in particular, PVA combined in one breath, may signify substantial patient distress or poor physiological circumstance that clinicians should investigate.
authors.affiliation: Department of Acute and Continuing Care, School of Nursing, University of Texas Health, Health Science Center at Houston, 6901 Bertner Avenue, Houston, TX 77030, USA. Electronic address: Karen.G.Mellott@uth.tmc.edu.
authors.forename: Karen G
authors.initials: KG
authors.lastname: Mellott
authors.affiliation: Department of Adult Health and Nursing Systems, School of Nursing, Virginia Commonwealth University, 1100 East Leigh St., P.O. Box 980567, Richmond, VA 23298-0567, USA.
authors.forename: Mary Jo
authors.initials: MJ
authors.lastname: Grap
authors.affiliation: Research and Innovation, College of Nursing, University of Southern Florida, 12901 Bruce B. Downs Blvd. MDC Box 22, Tampa, FL 33612, USA.
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Munro
authors.affiliation: Division of Pulmonary Disease and Critical Care Medicine, School of Medicine, Virginia Commonwealth University, P.O. Box 980050, Richmond, VA 23298-0050, USA.
authors.forename: Curtis N
authors.initials: CN
authors.lastname: Sessler
authors.affiliation: Department of Biomedical Engineering, School of Engineering, Virginia Commonwealth University, P.O. Box 843067, Richmond, VA 23284-3067, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Wetzel
authors.affiliation: Department of Respiratory Therapy, School of Allied Health Sciences, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1146, USA.
authors.forename: Jon O
authors.initials: JO
authors.lastname: Nilsestuen
authors.affiliation: Department of Biostatistics, School of Medicine, Virginia Commonwealth University, P.O. Box 980032, Richmond, VA 23298-0032, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Ketchum
mesh_terms: D016638:Critical Illness; D004868:Equipment Failure / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011446:Prospective Studies; D012119:Respiration; D012121:Respiration, Artificial / Q000295:instrumentation; D012122:Ventilators, Mechanical
keywords: Artificial; Mechanical; Patient ventilator asynchrony; Patient ventilator dyssynchrony; Patient ventilator interaction; Respiration; Ventilators