Blood Oxygenation During Air Ventilation in Dogs Before and After Water Instillation in the Lungs, Using Different Inflation Pressures and Expiratory Resistances

Abstract

Cardiorespiratory effects of intermittent positive pressure ventilation (IPPV) with air at different inflation pressures and after subsequent addition of expiratory resistance were studied before and after fresh water instillation. The increase in tidal volume which was produced resulted in a rise in Paoz. With expiratory resistance superadded, Pao2 mostly was lowered with lower inflation pressures, while with higher inflation pressures it generally rose. The blood pressure was generally lowered with increased inflation pressure, particularly so when adding positive end expiratory pressure (PEEP). While hardly influenced by any of the inflation pressures used, right atrial pressure rose and pulmonary arterial pressure generally showed a tendency to fall during PEEP.After fresh water instillation, increased inflation pressures without and with expiratory resistance produced a more pronounced effect. The circulatory effects were less pronounced though with the same trend. After water instillation when returning to lower inflation pressure without expiratory resistance, a further improvement in oxygenation was sometimes found. Ventilation with high inflation pressure and expiratory resistance, possibly intermittently administered, is therefore suggested in field conditions, e.g., when resuscitators with air are used.