2006 OPEN FORUM Abstracts
Leak Compensation Comparisons in Mechanical Ventilation
Jessica Patnaude, RRT, Keisha Smith, CRT, Ryan Totten, CRT, Joe Warren,
CRT, & Aaron Light BSRT RRT Ozarks Technical Community College, Springfield, MO
Background: A bench test was performed comparing leak compensation on the Maquet Servo i, Drager Evita 4, and the Viasys Avea. Using the same ventilator circuit for each ventilator a leak was created by opening the saline port on a Ballard suction catheter. Using the same ventilator settings the peak pressure, minute volume, measured rate, and exhaled tidal volume were measured. The intrinsic peep was measured by a Hans Rudolph Series 1101 breathing simulator. This study will confirm which ventilator tolerates a leak with a minimal change in parameters.
Method: A piece of large bore tubing was connected to a Hans Rudolph Series 1101 breathing simulator. Then a size 7.0 mm endotracheal tube was placed in the tubing and the cuff inflated to make sure there was no leak. Each ventilator was then attached to the endotracheal tube (ETT) using the same ventilator circuit. A Ballard closed system catheter was also placed in line with the circuit at the ETT. The breathing simulator was set for a resistance of 7 cmH20/l/sec, compliance of 40 ml/cmH20, and a set breath rate of 12. All ventilator parameters were set the same (VT 500ml, f 12, PEEP 5 cmH20, I.T. 1.2 seconds). The Viasys Avea and Maquet Servo I were placed in the pressure regulated volume control mode of ventilation while the Drager E4 was placed in CMV with auto-flow. The sensitivity on all ventilators was set for flow trigger. PIP, VE, measured f, exhaled VT and intrinsic PEEP was then noted without a leak. A leak was created by uncapping the saline port on the Ballard suction catheter and then all parameters were then noted with the leak.
|Drager Evita 4||Without Leak||With Leak|
|Peak Pressure||18 cmH2O||18 cmH2O|
|Minute Volume||5.7 L/min||5.2 L/min|
|Measured Rate||12 bpm||12 bpm|
|Tidal Volume Exhaled||489 ml||439 ml|
|Intrinsic PEEP||5 cmH2O||4.2 cmH2O|
|Viasys Avea||Without Leak||With Leak|
|Tidal Volume Exhaled||460||350|
|Maquet Servo I||Without Leak||With Leak|
|Tidal Volume Exhaled||493||378|
Conclusion: The Drager Evita 4 ventilator performed the
best with minimal changes in measured parameters. The Viasys Avea showed signs of auto
triggering but did not decrease the peak inspiratory pressure in response to
the leak. The Maquet Servo i did not
perform as well as the other two ventilators. Not only did it auto trigger but
also the peak inspiratory pressure decreased in response to the leak. We
believe this drop in pressure is due to the ventilator sensing the leak was a
sign of improved lung compliance.