Enhancement of mechanical ventilation of neonates by computer technology

Abstract

Mechanical ventilation is often required in the extremely small preterm infant because of transient failure of the immature control of breathing system, chest wall instability, weakness of the respiratory pump, and chronic lung disease. To better address some of these issues, computer algorithms have been developed for continuous automated control of the arterial hemoglobin oxygen saturation (by changing the fraction of inspired oxygen), of the tidal volume (by varying peak inspiratory pressure), and of minute ventilation (by changing respirator rate). Feasibility studies have shown that closed-loop computer control of physiologic target variables may stabilize oxygenation, decrease the transpulmonary pressure cost of ventilation, and expedite weaning from mechanical ventilation. In addition to synchronizing the upstroke in ventilator pressure with the onset of the spontaneous respiratory effort, computer technology may render the changeover from inspiration to expiration patient-cycled in a mode called pressure support ventilation. Proportional assist ventilation enhances ventilation in near perfect synchrony with the patient's spontaneous respiratory efforts. With this mode, the clinician selects gains for elastic and/or resistive unloading to tailor the ventilator pressure contour to the specific derangement in pulmonary mechanics (restrictive and/or obstructive). Most of these newer ventilatory strategies are as yet unproven and require randomized, controlled clinical study. Similarly, although on-line pulmonary mechanics monitoring during mechanical ventilation has become available with the adent of computer technology, its clinical utility is still not well established.