The Science Journal of the American Association for Respiratory Care

1997 OPEN FORUM Abstracts

THE EFFECT OF VENTILATORY MODE AND INSPIRATORY TIME ON GAS EXCHANGE DURING PARTIAL LIQUID VENTILATION (PLV) IN AN ACUTE LUNG INJURY MODEL

Yuji Fujino, MD, Max Kirmse, MD, Dean Hess, PhD, RRT, Robert M. Kacmarek, PhD, RRT Respiratory Care, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114

Perflubron acts as liquid PEEP, and has been shown to be an effective way for improving oxygenation in the injured lung. However, little information is available about different ventilation modes during PLV. We evaluated the efficiency of pressure controlled (PCV) and volume controlled (VCV) ventilation at various I:E ratio during PLV. Methods. Five sheep weighing 26.3±2.6kg had acute lung injury induced by warm saline lavage, followed by filling with 30mL/kg perflubron. Baseline ventilation was provided with a PB7200, VCV, rate 15/min, V_{T} 12mL/kg, I:E 1:2, F_{1}O_{2} 0.5 with PEEP set above the lower inflection point (LIP) on the pressure-volume (P-V) curve. VCV and PCV at 1:2, 1:1 and 2:1 I:E were compared in random order. During all modes V_{T} (VCV) and PIP (PCV) were adjusted to maintain a constant P_{PLAT} and total PEEP was kept constant. Results. PaO_{2} did not change significantly among modes. V_{D}/V_{T} during VCV 1:1 and VCV 2:1 was lower than during PCV 1:2. No hemodynamic differences were observed.

POST VCV1:2 VCV1:1 VCV2:1 PCV1:2 PCV1:1 PCV2:1

PaO_{2} 80±7 94±5 96±16 95±12 92±7 84±7 92±11

TV(mL) 348±33 332±15 339±28 352±34 313±38 322±40 355±59

VD/VT .58±.04 .51±.05 .49±.08* .49±.04* .58±.05** .52±.05 .51±0.05

CO(L/m) 4.4±0.6 4.6±1.3 4.5±1.0 4.2±1.3 4.7±1.3 4.3±0.7 4.5±1.4

POST: post injury, TV: tidal volume, CO: cardiac output. (MEAN ± S.D.)

*ANOVA p < 0.05 vs. POST ** p < 0.05 vs. VCV1:1

Conclusion. When PEEP is set above the LIP of the P-V curve, neither mode or I:E affects gas exchange or hemodynamics except V_{D}/V_{T} which improved with longer inspiratory times.

OF-97-120

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