1995 OPEN FORUM Abstracts
Pressure Volume Curves During Partial Liquid Ventilation
Constance R. Wise, BS. RRT; Ronald B. Hirschl, MD; Kenneth B. Bandy, BA, RRT; Carl F. Haas, MLS, RRT; Robert H. Bartlett, MD. Departments of Respiratory Care and Surgery, University of Michigan Medical Center, Ann Arbor MI
INTRODUCTION: Ventilation monitoring during mechanical ventilation includes waveform analysis. Pressure-volume (P/V) curves help to better understand the interplay between gas dynamics and lung compliance. We describe the use of P/V curves during partial liquid ventilation (PLV).
Methods: Ten patients were instilled with perflourocarbon ((PFC) Alliance Pharmaceutical Corp, San Diego CA), with either up to 40 mL/kg of ideal body weight or until a fluid meniscus was seen at end-exhalation in the ETT. Gas ventilation was performed using pressure control ventilation (7200ae, Puritan Bennett, Carlsbad CA). P/V curves were obtained with a respiratory mechanics monitor (CP-100, BICORE, Irvine CA) prior to, during and 24 hours after PFC administration. PFC could be administered daily for 7 days.
Results: Patients demonstrated similar changes in the shape of the P/V curves before, during and after administering PFC. These changes appeared to correspond with PFC fluid in the central airways. Figure A shows a normal P/V curve prior to instilling PFC. Figure B shows a characteristic "beak" during early inspiration, corresponding with PFC in the central airways. Figure C shows the return to a pre-fill P/V curve.
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CONCLUSION: Although the monitoring of V_T, SpO_2, and MAP indicate the patient's tolerance of PFC administration, the use of P/V curves may be beneficial in deciding the volume of PFC instilled during PLV. P/V curves demonstrate PFC in the central airways and its removal from the central airways via evaporation and/or alveolarization.