Abstract
During continuous positive pressure breathing(CPPB), proximal airway pressure(AP) and its mean value(MAP) reflect lung distending pressure, although their relationships to alveolar pressure (ALP) and its mean value(MALP) await definition. 10 infant lambs, under chloralose anesthesia and pancuronium bromide, were subjected to volume regulated, time cycled CPPB under conditions of constant inspiratory airflow. To estimate ALP, static recoil pressure was determined by interruption of airflow once every 10th breath, at a time in the respiratory cycle that was varied from trial to trial. From determinations of occlusion time, AP and ALP, real time AP and ALP curves were generated representing one respiratory cycle; MAP and MALP were calculated by integration; and the contribution to MALP of airway resistance(MALPr) was estimated from inspiratory(I) time, positive end-expiratory pressure(PEEP), peak ALP and MALP. Curves were generated at 25 and 50%, I, and at levels of PEEP between 0 and 11 mmHg.
Due to airway resistance, AP exceeded ALP in inspiration and ALP exceeded AP over much of expiration(E). Yet airway resistance contributed little to MALP. Over the range of PEEP applied, and at both %I, proximal mean airway pressure was an accurate and precise estimator of mean alveolar pressure.
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Fuhrman, B., Smith-Wright, D., Green, T. et al. 179 PROXIMAL AIRWAY AND AVEOLAR PRESSURES DURING MECHANICAL VENTILATION. Pediatr Res 19, 140 (1985). https://doi.org/10.1203/00006450-198504000-00209
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DOI: https://doi.org/10.1203/00006450-198504000-00209