Performance Assessment of 5 Transport Ventilators

Background: Use of transport ventilators is standard practice and recommended by professional organizations. Differences in performance may affect the level of care during transport. Methods: Five transport ventilators (CareFusion ReVel, Newport HT70, Phillips Trilogy, Drager Oxylog 3000, and Hamilton T1) were evaluated under passive conditions, comparing set VT to delivered VT, and the response to simulated patient demand using 2 models: COPD and ARDS. A Michigan Instruments Training and Test Lung (TTL) compliance 20 mL/cm H2O and resistance 5 cm H2O/L/s was used for passive evaluation. Ventilator settings on room air were: VT 300 mL x 10/min, PEEP 5 cm H2O; 300 x 10, PEEP 15; 300 x 20, PEEP 5; 300 x 20, PEEP 15; 500 x 10, PEEP 5; 500 x 10, PEEP 15; 500 x 20, PEEP 5; 500 x 20, PEEP 15. Delivered VT were measured with a Phillips NICO monitor. An IngMar 2000 Automated Test Lung was used for the dynamic evaluation: P 0.13 cm H2O, compliance 60 mL/cm H2O, inspiratory resistance 10 cm H2O/L/s, expiratory resistance 20 cm H2O/L/s (COPD) and compliance 20 mL/cm H2O, inspiratory resistance 5 cm H2O/L/s, expiratory resistance 5 cm H2O/L/s (ARDS). Each model was ventilated with: PSV = 5 cm H2O, PEEP 5 cm H2O; PSV = 5, PEEP 15; PSV = 10, PEEP 5; PSV = 10, PEEP 15. Sensitivity was set as sensitive as possible without auto-triggering. Trigger pressure (Tp) (difference between baseline and maximal pressure below baseline), time to trigger (TT) (beginning of pressure change below baseline to onset of gas delivery), and time to reach P90 (time from initiation of breath to 90% of peak inspiratory pressure). These measurements were made from the alveolar pressure tracing. Ten steady state breaths were evaluated in all VT trials and 5 breaths in dynamic evaluations. Results: The VT delivered by each ventilator differed significantly across each setting, P 10% difference, largest difference 74 mL (15%) ReVel ventilator, smallest difference 0.5 mL (0.1%) Hamilton ventilator. Tp achieved by each ventilator also differed across each setting, but TT and P90 were only significant, P 10%, for the ARDS models. The largest Tp 5. 1 cm H2O, Newport HT70, the smallest Tp 2.08 cm H2O Trilogy, the largest TT 219 ms Newport, the smallest TT 90 ms ReVel, and the largest P90 1032 ms Drager, the smallest P90 403 ms ReVel. Conclusions: Differences exist among transport ventilators regarding delivery of set VT and gas flow in response to simulated patient demand.