[Effects of positive end-expiratory pressure, tidal volume and perflubron doses on gas exchange during partial liquid ventilation].

The efficacy of gas exchange during partial liquid ventilation (PLV) may be affected by positive end-expiratory pressure (PEEP), tidal volume (TV) and perflubron (PFOB) dose. The purpose of the present study was to clarify which factors were important for improving gas exchange during PLV. Fourteen rabbits were anesthetized and tracheostomized. Lung was introduced with intravenous oleic acid combined with saline lung lavage. After obtaining control data, PFOB 7.5 ml.kg-1 was instilled into the trachea, and ventilation settings were changed sequentially [1. TV: 10 ml.kg-1 (mTV), 2. mTV with PEEP, 3. TV: 15 ml.kg-1 (hTV), 4. hTV with PEEP]. PEEP level was set to the lower inflection point. The PFOB dose was increased to 15 ml.kg-1 and measurements were repeated under each ventilation setting. PEEP increased PaO2 in all ventilation settings. In hTV ventilation settings, incremental dose of PFOB significantly increased PaO2. The PaO2 values of all hTV ventilation settings were significantly higher than those of corresponding ventilation setting of mTV. Pulmonary compliance was significantly decreased with PEEP in hTV ventilation in addition to 15 ml.kg-1 PFOB. The results suggested that adequate gas tidal volume was the most important factor for improving gas exchange during PLV. However, PEEP or larger dose of PFOB should be avoided because they may decrease pulmonary compliance.