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 VOLUME A/C ON THE LTV 1000

Matthew Seitz, Dan Neifert, 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 volume-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 H2O/L/sec; Compliance (CST) 20, 40 and 60 mL/cm H2O; rate 10/min. LTV 1000 settings: Mode Volume A/C, VT 600 mL, 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 23, 25, 26 and 28 cm H2O and VT of 569, 574, 574 and 571 mL; the 12-foot circuit had PIP of 23, 25, 26 and 28 cm H2O and VT of 561, 563, 559 and 556 mL. At CST 40: increasing RAW from 10-25, the 6-foot circuit had PIP of 10, 12, 14 and 16 cm H2O and VT of 592, 593, 589 and 583 mL; the 12-foot circuit had PIP of 11, 13, 15 and 17 cm H2O and VT of 596, 595, 590 and 585 mL. At CST 60: increasing RAW from 15-25, the 6-foot circuit had PIP of 9, 11 and 14 cm H2O and VT of 597, 601 and 591ml; the 12-foot circuit had PIP of 10, 12 and 14 cm H2O and VT of 616, 606 and 598 mL.

Conclusion: During volume-targeted, assist-control ventilation the delivered volume remained constant, but peak inspiratory pressure increased as resistance increased; however, the increased peak inspiratory pressure was similar with the 6-foot and 12-foot circuits.

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