Inspiratory Effort and Dynamic Transpulmonary Driving Pressure in Extremely Preterm Infants.

Abstract

In preterm infants receiving noninvasive ventilation, data about inspiratory effort (ΔP_es) and transpulmonary driving pressure (ΔP_L) are scarce. Electrical activity of the diaphragm (EAdi) can estimate ΔP_es and ΔP_L when patient size precludes more accurate measurements. This estimation may reveal new insights into respiratory pathophysiology and potential risk of self-inflicted lung injury in neonates receiving noninvasive support. What are the characteristics of ΔP_es and ΔP_L in extremely preterm infants undergoing noninvasive ventilation? Prospective, observational pilot cohort study, in which EAdi was recorded in neonates receiving noninvasive ventilation during recovery from respiratory distress syndrome (RDS), in those with evolving bronchopulmonary dysplasia (BPD), and in term controls. EAdi was used to estimate ΔP_es and ΔP_L. In a subset of patients with RDS and BPD, diaphragmatic thickening fraction (TF) and peripheral oxygen saturation (Spo₂)/Fio₂ were recorded. Ten patients with RDS, 25 patients with evolving BPD, and 5 control term neonates were studied. Average EAdi, ΔP_es, ΔP_L, and TF were similar between control infants and those with RDS and BPD. Inter-patient variability of ΔP_es (RDS, 24 [9]%; BPD, 28 [9]%; controls, 10 [6]%; P < .001) and ΔP_L (RDS, 25 [7]%; BPD, 27 [9]%; controls, 17 (7)%; P = .05) was higher in patients than in controls. Breaths with ΔP_es > 10 cm H₂O occurred more often in BPD than in RDS patients (P = .035) and control infants (P = .006). Breaths with ΔP_L > 20 cm H₂O occurred similarly in patients with BPD or RDS and more frequently than in control infants (P < .001). EAdi-based estimations correlated with TF, and ΔP_L had an inverse correlation with Spo₂/Fio₂ (ρ = -0.64; P = .018). ΔP_es and ΔP_L showed relevant variability in preterm infants. High ΔP_es was more common in patients with BPD than in those with RDS or control infants. High ΔP_L was observed in patients with BPD and RDS, occurred more often than in control infants, and correlated with the degree of oxygenation impairment.