AIRWAY FLOW PATTERNS DURING MECHANICAL VENTILATION OF INFANTS - MATHEMATICAL-MODEL

A mathematical model of flow in a patient-ventilator system is developed. The model is solved for conditions which simulate those which occur during mechanical ventilation of the small infant with lung disease. Unless a ventilator of extremely low compliance is employed, the airway flow is much less than, and lags the flow generated by the ventilator. Even if the flow generated is determined solely by the ventilator, the infant airway flow will change significantly when the pulmonary resistance or compliance changes. The infant flow may be so reduced during the initial part of inspiration that the effective inspiratory to expiratory time (I:E) ratio may be greatly decreased. This may, in part, explain the utility of using I:E ratios greather than 1.0 in infants to maintain positive pressure during a large part of the respiratory cycle. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc.