title: A ventilator requirement index.
abstract: OBJECTIVE
  To determine the efficacy of vital capacity (VC) and a proposed ventilator requirement index (VRI) for justifying ventilator prescription and use for patients with neuromuscular/chest wall diseases (NMD).
  
  
  METHODS
  Prospective observational study in which 319 patients with NMD, including 187 ventilator users, were separated into four groups: (1) asymptomatic, (2) abnormal specific screening factors and/or symptomatic, (3) ventilator use 8-20 hrs/day, and (4) >20 hrs/day of ventilator use. The VRI was defined as 60 x Ti/(Ttot)2 x (Vt/VC) x RR, where Ti = inspiratory time of one breath (secs), Ttot = total time of one breath (secs), Vt = tidal volume (ml) at rest, VC = vital capacity (ml), and RR = respiratory rate.
  
  
  RESULTS
  The overall analysis of variance F-tests and post hoc pairwise contrasts were significant (P < 0.001) for differences in the VC and VRI across groups. Thus, VC and VRI are independent predictors of group membership. Satisfying VC or VRI criteria signaled the highest number of patients benefiting from ventilator use.
  
  
  CONCLUSIONS
  The prescription of one or two ventilators can be justified by both VC and VRI, with the combination being most sensitive.
authors.affiliation: Department of Physical Medicine and Rehabilitation, UMDNJ-New Jersey Medical School, Newark, New Jersey, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Bach
authors.forename: Miguel
authors.initials: M
authors.lastname: Goncalves
authors.forename: Michal
authors.initials: M
authors.lastname: Eisenberg
authors.forename: Yuka
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: Eric
authors.initials: E
authors.lastname: Altschuler
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Winck
authors.forename: Eugene
authors.initials: E
authors.lastname: Komaroff
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009468:Neuromuscular Diseases / Q000150:complications*; D018579:Patient Selection; D011446:Prospective Studies; D012120:Respiration Disorders / Q000175:diagnosis*; D012121:Respiration, Artificial / Q000379:methods; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D035441:Thoracic Wall / Q000503:physiopathology; D014797:Vital Capacity