HIGH-FREQUENCY VENTILATION STRATEGIES WIT H NEONATAL CONVENTIONAL VENTILATOR - ASSESSMENT OF GAS-EXCHANGE, HEMODYNAMIC STATE AND LUNG INJURY

Experiments were performed to consider the use of conventional neonata l ventilators with assisted expiratory mechanism using ventilatory hig h frequency strategies. Gas exchange, hemodynamic state, and lung inju ry were also assessed. Twenty Albino Wistar rats, undergoing and acute lung lesion through physiological solution wash of the lungs were stu died. Afterward, they were distributed into four groups according to t he different ventilator strategies, based on the different pressure ch anges and the tidal volume, the baseline lung volume and the respirato ry frequency. Group !, High Frequency Ventilation, with high baseline rung volumes (HFVh); group II, Conventional Mechanical Ventilation, wi th high baseline lung volume (CMVh), group ill, High Frequency Ventila tion, with low baseline lung volume (HFV1) and group IV Conventional M echanical Ventilation, with low baseline lung volume (CMV1). Significa nt differences were found between group I (HFVh) and groups II (CMVh), III (HFV1) and IV (CMV1) as regards pO(2), Artery/Alveolar relation t o O-2 (a/A), pCO(2), arterial blood pressure and histopathologic lung lesion. The hypothesis concerning the decisive role of the baseline lu ng volume maintainance to minimize progressive damage caused by mechan ical ventilation on a previously injured lung while attending ventilat ory strategies that generate little pressure and volume cyclical chang es was confirmed. We conclude that, high frequency mechanical ventilat ion is possible through conventional neonatal respirators with assiste d expiratory mechanism.