2003 OPEN FORUM Abstracts
Using a dual control mode of ventilation in the neonatal/pediatric age range: Validation studies in four ventilators
Giulia Mesiano, RRT, Krishna Mullahoo, RRT, Michael Davis, MD.
Montreal Children's Hospital, McGill University Health Centre, Montreal, Quebec, Canada
AIM: With the advent of fifth generation ventilators, dual control modes are becoming popular in the pediatric setting. A bench study to validate the accuracy of measured tidal volume (Vt) and peak inspiratory pressure (PIP) of four ventilators that offer this mode was performed.
Methods: Four ventilators (Siemens Servo 300, Tyco Healthcare Puritan Bennett 840, Viasys Avea, Dräger Evita 4) were used to ventilate a neonatal test lung (Manley neonatal lung simulator, Online Medequip Ltd). The ventilator circuit used was a dual heated wire circuit (Allegiance Airlife-Infant) with a Fisher & Paykel MR290 humidifier chamber (dry and unheated). Circuit compliance (Ccirc) = 1.1 ml/cmH2O. Identical dual control parameters were used in the neonatal/pediatric range: PRVC (Servo300, Avea), VC+ (PB840), Vol SIMV autoflow in Neomode (Evita4). RR 30 bpm, Set Vt: 30 ml., PEEP 5 cmH2O, Ti: 0.50 sec., Flow cycle:0, Rise Time: 50%, FiO2: 0.21. The test lung was ventilated with Clung set at 1.0 and 0.5 ml/cmH2O. Displayed Vt was recorded. Delivered Vt was measured using a stand alone Infant PFT system (Raytech Instruments, Vancouver) placed proximal to the neonatal lung simulator.
RESULTS: In all ventilators, there was a significant difference (p<0.01) in measured Vt and PiP when lung compliance was changed from 1.0 to 0.5 ml/cmH20. None of the ventilators tested were able to deliver the target tidal volume, even though all other set parameters were consistent.
CONCLUSION: Simulation of a clinical change in lung compliance resulted in significant changes in delivered tidal volumes. There was great variability between ventilators in regards to their pressure-saving strategies. This may be due, in part, to fundamental operating differences in set tidal volumes between these ventilators.
Test Recording Format:
C = 1 ml/cmH2O C = ml/1 cmH2O C = 0.5 ml/cmH2O C = ml/1 cmH2O C = 1 ml/cmH2O
VC PRVC PRVC PRVC VC
|Servo300||14.2*||20.2 *||13.9||20.2||9.2||24.6||15.8||21.8||14.2 *||20.3 *|
* = square wave