The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

USE OF HEAT & MOISTURE EXCHANGERS TO REDUCE PERFLUBRON EVAPORATIVE LOSS IN PARTIAL LIQUID VENTILATION IN SWINE.

Michelle C. Mazzoni, Ph.D., K. Michael Sekins, Ph.D., Patricia D. Rusheen, Muriel L. Spooner, B.S., John Hoffman, B.S., Ughetta del Balzo, Ph.D., and Stephen F. Flaim, Ph.D. Alliance Pharmaceutical Corp., 3040 Science Park Road, San Diego, CA 92121.

Partial liquid ventilation (PLV) is in clinical trials as a treatment for patients with acute respiratory distress in which the lungs are filled with LiquiVent(R) (sterile perflubron, Alliance Pharmaceutical Corp. and Hoechst Marion Roussel) while on conventional mechanical ventilation (CMV). We hypothesized that the use of a heat & moisture exchanger (HME) in PLV would retard perflubron evaporative loss and thereby minimize redosing requirements. In this study, two HMEs (Baxter HEPA/HCH and Hudson RCI AQUA+ FH) were evaluated for safety (pressure drop, [delta]P, across HME and development of auto-PEEP) and efficiency to retain expired perflubron vapor (compare volume of perflubron evaporated with and without HME). Swine (37-48 kg) were anesthetized, paralyzed, and ventilated with measurement of hemodynamics and lung mechanics at baseline and during 5 h of PLV or CMV (TV = 13 mL/kg, RR = 20/min, I:E = 1:2.3, PEEP = 10 cm H_{2}O). There were five animal groups: Hudson-PLV (n=13), Hudson-CMV (n=10), Baxter-PLV (n=8), Baxter-CMV (n=7), and PLV only (n=11). PLV animals received 30 mL/kg perflubron and evaporative loss was calculated as expired minute ventilation times the concentration of expired perflubron as measured by a specialized infrared absorption technique. The [delta]P across each HME was determined before (dry) and after 5 h of animal ventilation using an in vitro apparatus (ISO 9360 specifications) with flow rates of 30, 60, and 90 L/min. Results for perflubron evaporative loss and HME [delta]P at 60 L/min (expired flow direction) are shown in table (mean ± SEM). PLV did not significantly affect the [delta]P.

Perflubron Evaporative Loss [delta]P (cm H_{2}O)

(mL/kg/h) before use after use

Hudson-PLV 0.74 1.2±0.1 1.2±0.1

Hudson-CMV N/A 1.3±0.1 1.3±0.0

Baxter-PLV 0.61 2.5±0.1 2.6±0.1

Baxter-CMV N/A 2.5±0.1 2.5±0.1

PLV only 1.15 N/A N/A

There were no significant differences among HME groups in terms of hemodynamic or lung mechanics parameters and further, there was no development of auto-PEEP. We conclude that HME use with these devices during PLV is safe and reduces evaporative loss by about 35-45% depending on choice of HME.

OF-97-099

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