The effect of mechanical ventilation on pulmonary blood flow has both experimental and clinical implications. Most major surgical procedures are currently being done while using mechanical ventilation. Experimental plans often require thoracotomy and, hence, mechanical ventilation.
This study was aimed at evaluating alterations in pulmonary blood flow resulting from ventilation with three commonly used mechanical ventilators.
Methods
Eleven mongrel dogs weighing from 10.9 to 21.31 kg were studied under light intravenous sodium pentobarbital (12 mg/kg) anesthesia. Each animal was intubated with a cuffed endotracheal tube, and mechanical ventilation with room air was accomlished by one of three ventilators: a) intermittent positive-negative piston type (Jefferson*), b) continuous positive pressure operated diaphragm (pneophore†), or c) positive-negative pressure operated diaphragm (anesthetizer-vaporizer-resuscitator, [A-V-R] ‡). Polyethylene catheters of identical dimensions were placed in a peripheral artery, the pulmonary artery, and the left atrial appendage. From these, arterial pressure and pulmonary artery less atrial differential pressure