Backup ventilation during neurally adjusted ventilatory assist in preterm infants

To analyze the proportion of backup ventilation during neurally adjusted ventilatory assist (NAVA) in preterm infants at different postmenstrual ages (PMAs) and to analyze the trends in backup ventilation in relation to clinical deteriorations.

A prospective observational study was conducted in 18 preterm infants born at a median (range) 27⁺⁴ (23⁺⁴ -34⁺⁴ ) weeks of gestation with a median (range) birth weight of 1,100 (460-2,820) g, who received respiratory support with either invasive or noninvasive NAVA. Data on ventilator settings and respiratory variables were collected daily; the mean values of each 24-h recording were computed for each respiratory variable. For clinical deterioration, ventilator data were reviewed at 6-h intervals for 30 h before the event.

A total of 354 patient days were included: 269 and 85 days during invasive and noninvasive NAVA, respectively. The time on backup ventilation (%/min) significantly decreased with increasing PMA during both invasive and noninvasive NAVA. The neural respiratory rate did not change over time. The median time on backup ventilation was less than 15%/min, and the median neural respiratory rate was more than 45 breaths/min for infants above 26⁺⁰ weeks PMA during invasive NAVA. The relative backup ventilation significantly increased before the episode of clinical deterioration.

The proportion of backup ventilation during NAVA showed how the control of breathing matured with increasing PMA. Even the most immature infants triggered most of their breaths by their own respiratory effort. An acute increase in the proportion of backup ventilation anticipated clinical deterioration.