The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

EVALUATION OF 6 AND 12-FOOT CIRCUIT LENGTHS ON DELIVERED VOLUME AND PRESSURE DURING PRESSURE A/C ON THE LTV 1000

Dan Neifert, Matthew Seitz, Lonny Ashworth MEd RRT, Boise State University, Boise, ID.

Background: The purpose of this study was to determine how 6-foot and 12-foot adult circuit lengths affect the delivered volume and peak pressure during pressure-targeted, assist-control, using the LTV 1000 for patients desiring longer circuits to provide more mobility.

Method: The LTV 1000 was connected to the Hans Rudolph Breathing Simulator (HR1101). HR1101 settings: Resistance (RAW) 10, 15, 20 and 25 cm H20/L/sec; Compliance (CST) 20, 40 and 60 mL/cm H20; rate 10/min. LTV 1000 settings: Mode Pressure A/C, Pressure 20 cm H2O, rate 5/min, TI 1.0 sec, PEEP 5 cm H2O. A minimum of five breaths was recorded at each setting as compliance and resistance were changed, with the 6-foot circuit and the 12-foot circuit.

Results: At CST 20: increasing RAW from 10-25, the 6-foot circuit had PIP of 28, 25, 24 and 23 cm H2O and VT of 598, 537, 517 and 489 mL; the 12-foot circuit had PIP of 30, 26, 25 and 24 cm H2O and VT of 603, 516, 494 and 474 mL. At CST 40: increasing RAW from 10-25, the 6-foot circuit had PIP of 27, 25, 23 and 23 cm H2O and VT of 1060, 920, 798 and 720mL; the 12-foot circuit had PIP of 28, 25, 24 and 23 cm H2O and VT of 1032, 901, 778 and 689 mL. At CST 60: increasing RAW from 10-25, the 6-foot circuit had PIP of 27, 23, 23 and 22 cm H2O and VT of 1421, 1120, 923 and 793mL; the 12-foot circuit had PIP of 28, 24, 24 and 22 cm H2O and VT of 1386, 1099, 906 and 748 mL.

Conclusion: During pressure-targeted, assist-control ventilation there is minimal affect on delivered volume and peak inspiratory pressure when changing from a 6-foot circuit to a 12-foot circuit.

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