The Science Journal of the American Association for Respiratory Care

2007 OPEN FORUM Abstracts

EFFECTS OF TIDAL VOLUME DELIVERY USING SMOOTH INTERNAL BORE TUBING VS WIDE BORE CORRUGATED TUBING FOR NPPV. A BENCH STUDY.

S. R. Ogrinc1, K. Conry1, J. Karthan2, J. E. Martin1

Background: Noninvasive positive pressure ventilation (NPPV) is being used frequently in an attempt to avoid intubation. Today NPPV circuits utilize an internal smooth wall surface to deliver a less turbulent flow. We have found that various interfaces are necessary for the success of NPPV. Some interfaces have exhalation ports built into the mask. This requires the purchase of multiple circuits some with and without exhalation ports. We hypothesized that a reduction of different circuits for NPPV could be accomplished if an alternative circuit could be constructed. This study was done to see if turbulent flow from a cut to length corrugated wide bore tubing (non-smooth wall internal surface) would affect tidal volume delivery.

Method: A standard Respironics BiPAP Disposable Single Circuit (Respironics, Inc., Murrysville, Pa.) was compared to a circuit constructed of corrugated wide bore tubing, Airlife- Corrugated Flexible Polyethylene(Cardinal Health, McGaw Park, Illinois)cut similar in length from a 100 foot roll. A Respironics disposable exhalation port completed the circuit. A mechanical test lung model (TTL, 2600I ; Michigan Instruments, Grand Rapids, MI) was used with a compliance of .08 L/cmH2O, and a resistance of RP 5. A Respironics BiPAP ST/D-30 (Respironics, Inc., Murrysville, Pa.) was set in the timed mode, rate of 12, and 30% inspiratory time. Six tests were performed at settings of Inspiratory Pressures (IPAP) and Expiratory Pressures (EPAP): 10/5, 15/5, 20/5, 20/10, 20/5 with a 10 Lpm leak (simulating a patient leak), and 20/5 with resistance of RP 20. A CO2/Flow Sensor monitor (NICO, Respironics Novametrix, LLC, Wallingford, CT) was placed distal to the circuit to display exhaled tidal volumes (VTE) and confirmed BiPAP settings. Each circuit was attached to the test lung and given 5 minutes to equilibrate before 12 readings were recorded.

Results:
The mean results between the Respironics tubing and the disposable corrugated wide bore tubing were: 0, 7, 4, 8, 0, and 2ccs respectively in the order of testing.

Conclusion:
A circuit constructed of corrugated wide bore tubing with a disposable exhalation valve appears to be a suitable alternative to the Respironics NPPV circuit when using the BiPAP ST/D 30 machine. Performance of other NPPV machines, patient circuits, and clinical applications may be necessary.


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