The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

A EVALUATION OF AUTOMATIC TUBE COMPENSATION IN TWO MECHANICAL VENTILATORS UTILIZING A SIMULATED SPONTANEOUS BREATHING MODEL.

S. Richey1, D. Long2


Background: Automatic Tube Compensation (ATC) is utilized during a Spontaneous breathing trial to compensate for the variable flow-dependent resistance of the endotracheal tube and mimic post-extubation breathing. Many manufacturers have incorporated ATC systems into commercially available ventilator software; however, commercial implementations differ from the original ATC model. The purpose of this study was to assess the flow-adapted compensation of automatic tube compensation between the Puritan-Bennett 840 ventilator (PB 840) (Tyco Healthcare, LLC) and the Hamilton Raphael XTC ventilator (Hamilton Medical, Inc.).

Methods: The two Ventilators under investigation were alternatively connected to a simulated spontaneous breathing model consisting of a dual chamber, Double TTL test lung (Michigan Instruments). One test lung (driving model) was powered by a PB 840 ventilator using minimum settings to generate spontaneous breathing of a second test lung (spontaneous model).The Assist Control Pressure Control (AC/PC) mode was used for the driving ventilator with the following settings: PC of 8 cmH2O, RR 12 bpm, I-time 1.0 seconds, PEEP 5 cmH2O. An endotracheal tube with an inner diameter of 7.0 mm was used. Test conditions consisted of changing the Rise Time setting by 10% in 10 stages (baseline of 1% to100%) to simulate different peak inspiratory flow rates. Three different levels of compensation were assessed (80, 90, &100%). Each stage consisted of a direct observation of the compensation pressure (Peak Pressure-PEEP) for each change in the rise time setting.

Results: The PB 840 increased compensation pressure with each increase in ATC percent & with various stages of increased rise time percent. Conversely, the Raphael’s compensation pressure did not change from baseline compensation pressure after both increases in ATC percent & increased rise time percent. The difference between each ventilator in identical test situations was statistically significant (p < 0.01) (table 1).

Conclusion: The findings of this study reveal that ATC systems differ in relation to compensation pressure. The PB 840 provided significantly more compensation pressure in all simulations than the Hamilton Raphael XTC.


Compensation Pressure with changes in Rise Time % & increases in percent tube compensation.
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