title: A method for monitoring and improving patient: ventilator interaction.
abstract: OBJECTIVE
  To evaluate a new approach for monitoring and improving patient-ventilator interaction that utilizes a signal generated by the equation of motion, using improvised values for resistance and elastance obtained noninvasively.
  
  
  METHODS
  Observational study in intensive care units in five European centers.
  
  
  METHODS
  We studied 21 stable patients instrumented with esophageal/gastric catheters for a previous study and ventilated alternately with pressure support (PSV) and proportional assist (PAV) ventilation with a Tyco 840 ventilator.
  
  
  RESULTS
  Previously recorded digital files were analyzed in real-time by a prototype incorporating the new technology (PVI monitor, YRT, Winnipeg, Canada). Actual onsets (P(DI)-T(ONSET)) and ends (P(DI)-T(END)) of inspiratory efforts, ineffective efforts, and patient respiratory rate were identified visually from transdiaphragmatic or calculated respiratory muscle pressure. Monitor-identified T(ONSET) occurred 0.107 +/- 0.074 s after P(DI)-T(ONSET), substantially less than trigger delay observed with conventional triggering (0.326 +/- 0.086 s). End of effort was identified 0.097 +/- 0.096 s after P(DI)-T(END), significantly less than actual cycling-off delay during PSV (0.486 +/- 0.307 s) or PAV (0.277 +/- 0.084 s). The monitor detected 80% of ineffective efforts. There was excellent agreement between monitor-estimated respiratory rate and actual patient rate over a wide range (17-59/min) of patient rates (mean (+/- SD) of difference -0.2 +/- 1.9/min for pressure support and 0.2 +/- 0.9/min for proportional assist) even when large discrepancies existed (> 35/min) between patient and ventilator rates.
  
  
  CONCLUSIONS
  The proposed approach should make it possible to improve patient-ventilator interaction and to obtain accurate estimates of true patient respiratory rate when there is nonsynchrony.
authors.affiliation: mkyounes@shaw.ca
authors.forename: Magdy
authors.initials: M
authors.lastname: Younes
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
authors.forename: Salvatore
authors.initials: S
authors.lastname: Grasso
authors.forename: John
authors.initials: J
authors.lastname: Kun
authors.forename: Jordi
authors.initials: J
authors.lastname: Mancebo
authors.forename: Marco
authors.initials: M
authors.lastname: Ranieri
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Richard
authors.forename: Henry
authors.initials: H
authors.lastname: Younes
mesh_terms: D005060:Europe; D006801:Humans; D007362:Intensive Care Units; D008499:Medical Records; D008991:Monitoring, Physiologic / Q000379:methods*; D019370:Observation; D012121:Respiration, Artificial / Q000379:methods* / Q000592:standards; D016896:Treatment Outcome