The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

Comparison Between the Fabius and Apollo Anesthesia Ventilators and the Drager Evita 4 Critical Care Ventilator During Pressure Control Ventilation: A Bench Model Study

Tom Blackson, BS, RRT1, 2, Andrew Ginn, RRT1, Mark Schneider, MD. Christiana Care Health System, 2Delaware Technical and Community College, Wilmington Campus, DE. 

Background: Pressure control (PC) ventilation is used with increased frequency in the ICU setting. Conventional anesthesia ventilators are limited to volume control (VC) ventilation. In many instances, PC ventilated ICU patients requiring anesthesia must be transitioned to a VC mode during surgery or rely on a critical care ventilator to provide PC ventilation during surgery. Two anesthesia ventilators, the Fabius and Apollo, are currently being marketed with a PC option to be used during surgery

Purpose: To compare the performance characteristics of the Fabius (F) and Apollo (A) anesthesia ventilators to the Drager Evita 4 (D) critical care ventilator when providing PC ventilation to a bench model of ARDS. 

Methods: An ARDS patient was simulated using a Michigan test lung: compliance = 0.02 L/cm H2O and a #5 parabolic resistor (PR) to simulate airway resistance. A differential pressure transducer, (Novametrix, Wallingford , PA ), was placed between the PR and each test ventilator to measure VT, f, MV, PIP, PEEP, PIFR, and mean airway pressure, (Paw). Ventilators were tested using PIP: 20 & 30 cm H2O, TI: 1.7 sec., PEEP: 10 cm H2O. The F was tested using a set PIFR of 35 L/min. and 70 L/min. The D was tested using a slope of 0 and 0.2. The A offered no setting for PIFR adjustment. Data was collected over a one minute time period.  

Results: The F and A anesthesia ventilators ventilated at significantly lower MV, VT, PIFR, and Paw than the D critical care ventilator, (p < 0.05). The PIP and PEEP levels were insignificantly different among the three ventilators tested, (p > 0.05). 

Table displays test conditions with PIP set at 30 cm H2O.  Values listed (± SD).                                                          

Parameter F PIFR 35 F PIFR 70 A D slope 0 D slope 0.2
MV (L) 6.66   (0) 6.34    (0.1) 6.20  (0.1) 9.77   (0) 9.06   (0)
VT    (L) 369.5 (0.5) 351.7  (3.9) 343.9 (6.8) 542.5 (0.5) 503.1 (2.8)
PIP (cm H2O)   30.0 (0)   29.1  (0.1)   30.5 (0.1)   32.2 (0)   32.3 (0)
PEEP (cm H2O)   10.3 (0.1)   10.3  (0.1)   10.1 (0.1)   10.2 (0)   10.2 (0)
Paw (cm H2O)   18.6 (0.1)    19.5 (0)   19.8 (0.1)   20.3 (0)   20.9 (0)
PIFR (L/min.)   32.2 (0.9)    57.9 (0.2)   56.9 (0.3)   90.1 (0.5) 100.8 (0.6)

Conclusions: The anesthesia ventilators tested do not deliver PC ventilation comparable to the D critical care ventilator.  The differences in VT and MV may result in hypoventilation of patients transitioned from the D to either the F or A for surgery. The difference in Paw may result in deterioration of oxygenation in patients transitioned from the critical care ventilator to either anesthesia ventilator. Further clinical testing is warranted.

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