Inductance Plethysmography in Preterm Newborns Under Volume Guarantee Ventilation: A Crossover Study.

Abstract

Introduction: The diaphragm of preterm newborns is flat, weak and horizontally inserted in the rib cage. Consequently, it hampers the lever mechanism during muscle contraction, reduces the efficiency of pulmonary ventilation and chest expansion and increases energy expenditure.

Objective: Primary outcome was to assess chest expansion using inductance plethysmography in preterm newborns during assist-control ventilation and inspiratory pressure control with and without volume guarantee (AC-PC and VG, respectively) and secondary outcomes were to assess ventilatory and autonomic outcomes.

Methods: Chest expansion, as well as ventilatory (peak pressure, minute volume, dynamic compliance and airway resistance) and autonomic outcomes (heart rate, respiratory rate and peripheral oxygen saturation), were measured at 0, 30 and 60 min after initiation of ventilation in a crossover clinical trial study. A 30-min wash-out was performed between changes in ventilation modes.

Results: We analysed 450 respiratory cycles of preterm newborns between 27 and 32 gestational age (weighted 964 ± 167.1 g). Chest expansion was higher in VG in T0 (p = 0.01), T30 (p < 0.01) and T60 (p = 0.04). Ventilatory outcomes are similar between two modes. Heart rate in VG mode was lower than AC-PC at T60 (p < 0.01), whereas peripheral oxygen saturation (SpO₂) was higher at the three moments, being significant at T30 (p = 0.02). Although nonsignificant, respiratory rate was lower for VG when compared to AC-PC.

Conclusion: VG may increase chest expansion and peripheral oxygen saturation compared with AC-PC mode, and reduce heart rate.