Efficacy of Neurally Adjusted Ventilatory Assist in Preterm Newborns with Respiratory Distress Syndrome

Presenter: G. Genoni (e-mail: [e-mail])

Introduction: Neurally adjusted ventilatory assist (NAVA) is a technique of partial respiratory support that is triggered by the electrical signal of the diaphragm muscle. Pressure assistance is provided in proportion to and synchronous with the electrical activity of the diaphragm (EAdi). Few data exist about the efficacy of NAVA in ventilated newborns and only for short times. The aim of this study was to assess in a cohort of preterm newborns the efficacy and safety of NAVA used for a long period.

Materials and Methods: Premature infants aged < 28 days, requiring intubation for respiratory distress syndrome or sepsis were ventilated with NAVA (Servo-N, Maquet Critical Care, Solna, Sweden) after 12 consecutive hours of conventional mechanical ventilation (SIMV + VG). NAVA level was set to obtain an expiratory tidal volume (VT) comprised between 4 and 7 mL/kg. Ventilator default setting for neural inspiratory (0.5 cm H₂O/μV) and expiratory trigger threshold (70% of EAdi peak) were unmodified, while an inspiratory airway pressure limit of 25 cm H₂O was set. PEEP was maintained between 4 and 6 cm H₂O, fraction of inspired oxygen (FiO₂) was the same as in conventional ventilation. For each patient we evaluated ventilation parameters, recorded every 6 hours, and the incidence of short term complications (death, pneumothorax, and reintubation within 72 hours).

Results: Overall, 26 preterm newborns were enrolled in this study. The median gestational age (GA) was 32⁺² weeks (range: 27+4 to 35+6) and the median weight was 1,220 g (range: 660–2,730). The mean time of intubation was 9.5 hours of life. Patients underwent NAVA for 95 mean hours. After 6 hours of NAVA, we found a significant reduction of FiO₂ (mean FiO₂ 0.34 vs. 0.27; p < 0.01) and PIP (mean PIP: 20 vs. 13 mm Hg; p < 0.01) and a significant increase of pulse oximetric saturation Spo₂/Fio₂ (SF) ratio (mean SF: 300 vs. 373; p < 0.01) without a significant increase of PaO₂, compared with conventional mechanical ventilation parameters. This improvement in ventilation parameters and oxygenation indices persisted during NAVA ventilation until the extubation. No death, pneumothorax or reintubation was recorded in the whole group.

Conclusion: NAVA seems to be safe and effective to manage premature infants in need for mechanical ventilation, even for a long period, until the extubation.

Keywords: neurally adjusted ventilatory assist, preterm newborns, respiratory distress syndrome, efficacy, safety