Abstract
Conventional gas ventilation is often unsuccessful for premature neonatal patients suffering from acute respiratory distress syndrome (ARDS). For such patients, liquid ventilation (LV) with perfluorocarbon (PFC) liquids has been proposed. By eliminating the air-liquid interface in saccules (the premature gas exchange structures), where scarce or absent surfactant production exists, pulmonary instability is avoided, lung compliance is improved and atelectatic saccules are recruited, ultimately lowering the saccular pressure. Tidal LV involves administrating a liquid tidal volume to the patient at each respiratory cycle, therefore requires a dedicated circuital setup to deliver, withdraw and refresh the PFC during the treatment. We have developed a prototype Liquid Ventilator. The apparatus comprises two sub-circuits, managed by a personal computer-based control system. The ventilation sub-circuit performs inspiration/expiration with two sets of peristaltic pumps. A system for the evaluation of the true inspired/expired volumes was devised, consisting of two reservoirs equipped with pressure transducers measuring the hydraulic head of the fluid therein. Volume accuracy was ±0.3ml. The refresh sub-circuit properly processes the PFC by performing filtration (DFA, Pall Corp, NY), oxygenation, CO2 scavenge, and heat exchange (SciMed 2500, Life Systems Inc, MN). The new apparatus has been employed in preliminary in vivo animal tests on five newborn mini-pigs with induced ARDS. The animals were successfully supported for four hours each. Mean arterial POL was 131.4mmHg (range 79.0–184.2) mean arterial pCO2 was 64.8mmHg (range 60.0–73.4).
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