The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

EFFECT OF ALTITUDE ON TIDAL VOLUME AND PEAK INSPIRATORY PRESSURE DURING VOLUME-TARGETED A/C USING THE LTV 1000 AND HT 50

Susan Marmentini, Denise Y. Chase, Lonny Ashworth RRT, Boise State University , Boise ID.

Background:  During volume-targeted A/C, the delivered tidal volume (Vt) should remain constant regardless of altitude. The Vt and peak inspiratory pressure (PIP) at different altitudes were evaluated using the Newport HT 50 and the Pulmonetics LTV 1000.

Method: The testing altitudes were 2938, 5600 and 8890 feet.  Each ventilator was connected to the Hans Rudolph Electronic Breathing Simulator (HR 1001). HR 1101 settings: Resistance (Raw) 5, 15 and 25 cm H2O/L/sec; Compliance (Cst) 20, 40, 60 and 80 mL/cm H2O. LTV 1000 and HT 50 settings: Volume-Targeted A/C; Rate 8/minute; Tidal Volume 600 mL; PEEP 5 cm H2O; TI 1.0 second. Tidal volume and PIP were the average of five breaths as the altitude, compliance and resistance were changed.  Recorded values were: LTV 1000 displayed values (LTV), HR 1101 measured values with the LTV 1000 (HR-LTV), HT 50 displayed values (HT) and HR 1101 measured values with the HT 50 (HR-HT).                                                                                                                                       

Results: Tidal volume with a Cst of 40 mL/cm H2O and Raw of 15 cm H2O/L/sec: at 2938 ft LTV 552 mL, HR-LTV 588 mL, HT 596 mL and HR- HT 529 mL; at 5600 ft LTV 558 mL, HR-LTV 615 mL, HT 595 mL and HR-HT 546 mL; at 8890 ft LTV 561 mL, HR-LTV 670 mL, HT 599 mL and HR-HT 552 mL.

Peak inspiratory pressure with a Cst of 40 mL/cm H2O and Raw of 15 cm H2O/L/sec: at 2938 ft LTV 23.6 cm H2O, HR-LTV 23.6 cm H2O, HT 26.4 cm H2O and HR-HT 24.8 cm H2O; at 5600 ft LTV 25.0 cm H2O, HR-LTV 25.6 cm H2O, HT 26.0 cm H2O and HR-HT 25.2 cm H2O; at 8890 ft LTV 27.4 cm H2O, HR-LTV 27.7 cm H2O; HT 26.0 cm H2O and HR-HT 25.4 cm H2O.

Conclusion:  With an increase in altitude the tidal volumes and peak pressures may increase, depending upon the ventilator. Tidal volumes and peak inspiratory pressures should be carefully monitored during transportation at different altitudes.


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