Poster presentation | Open | Published:
Comfort of different types of ventilators in noninvasive ventilation
Critical Carevolume 8, Article number: P12 (2004)
We asked whether there are differences in breathing comfort between ventilators using blowers or valves for flow generation. We also studied Zeus®, a new anaesthesia workstation with a closed breathing circuit that allows augmentation of spontaneous breathing.
Eleven healthy, awake volunteers (six female, five male;35 ± 6 years) supplied with fixed standard nose masks (Respironics) were connected to seven different ventilators. Three were blower based: BiPAP Vision® (Respironics), Breas LTV 1000® (Pulmonetic Systems), Zeus® (Dräger Medical); and four were valve based: Evita 2®(Dräger Medical), PB 840® and PB 7200® (Puritan Bennett), Veolar® (Hamilton Medical). Four ventilatory modes were used: continuous positive airway pressure (CPAP) (positive end expiratory pressure [PEEP] 3 mbar), pressure support ventilation (PSV) (pressure support [PS] 5 mbar, PEEP 3 mbar), pressure-controlled synchronized intermittent mandatory ventilation (PC-SIMV) (10 bpm, Pinsp 10 mbar, PS 5 mbar, PEEP 3 mbar), and volume-controlled synchronized intermittent mandatory ventilation (VC-SIMV) (10 bpm, VT 6 ml/kg, PS 5 mbar, PEEP 3 mbar). Volunteers were instructed to breathe freely for a few minutes. Sixteen questions concerning cycling and breathing effort during inspiration (I) and expiration (E) had to be answered on a scale from 1 (very good, extremely comfortable) to 5 (very poor, extremely uncomfortable). Two final questions evaluated breathing comfort during I and E as a whole. SPSS® 11.0, ANOVA, P < 0.05.
Breathing comfort differed significantly between the ventilatory modes (VC < PC < PSV < CPAP; P < 0.001). To compare ventilators, PC-SIMV and VC-SIMV were excluded, as BiPAP Vision® is not capable of delivering these modes. During E blower-based ventilators were scored better (2.2 ± 1.0 versus 2.6 ± 0.9; Fig. 1).
Awake volunteers experience PC and VC ventilatory modes – although synchronized and with supported spontaneous breaths – as extremely unpleasant. Differences between ventilators are far less, but during expiration blower-based ventilators scored better than valve based. Despite its totally closed breathing circuit, Zeus® belonged to the more comfortable group of ventilators.