Postmenstrual age at discharge in premature infants with and without ventilatory pattern instability

Tracheostomy Tube Change Versus PEEP Titration on Tracheostomy-Dependent Infants With Airway Malacia and Ventilator Instability

OBJECTIVE

To investigate the impact of positive end-expiratory pressure (PEEP) titrations or tracheostomy size change (trach change) on ventilation stability in infants with tracheobronchomalacia.

STUDY DESIGN

A retrospective chart review.

SETTING

Tertiary care children's hospital from 2015 to 2023.

METHODS

A retrospective chart review on ventilator and tracheostomy-dependent patients <1 year of age. Demographics, bronchoscopic findings, and ventilator outcomes within 14 days were recorded. Analysis was performed with chi-square, Fisher's exact, binomial regression analysis, and two-tailed t tests.

RESULTS

Of 71 patients (66% male, median 6.1 months old [interquartile range, IQR, 4.6-7.3]) who underwent 74 initial bronchoscopies, the PEEP titration cohort (n = 37) experienced an improvement (narrower) in 24-hour mean ventilatory ranges (peak inspiratory pressure [PIP] 5.6 pre vs 2.9 post, P = .01; fraction of inspired oxygen [FiO2] range 5% vs 3%, P = .04), whereas the trach change cohort did not (PEEP 5.9 vs 5.6, P = .8; FiO2 10% vs 5%, P = .07). In patients with airway malacia, the PEEP titration cohort had improved PIP ranges postintervention (5.5 vs 3.0, P = .02), whereas the trach change cohort did not (4.4 vs 6.6, P = .13). In patients without airway malacia, trach change correlated with improved PIP (8.4 vs 3.8, P = .04). Repeat bronchoscopy after initial intervention was significantly more common after trach change compared to PEEP titration (22% vs 3%, P = .01).

CONCLUSION

PEEP titration was associated with improved PIP and FiO2 ventilatory outcomes with a lower rate of repeat bronchoscopy compared to trach change, suggesting trach change alone may have little impact with greater subsequent interventional needs compared to PEEP titration.

Ventilatory response and stability of oxygen saturation during a hypoxic challenge in very preterm infants

BACKGROUND

Preterm infants have immature control of breathing and impaired pulmonary gas exchange. We hypothesized that infants with bronchopulmonary dysplasia (BPD) have a blunted ventilatory response and peripheral oxygen saturation (SpO₂ ) instability during a hypoxic challenge.

METHODS

We evaluated the response to hypoxia in 57 very preterm infants (38 no BPD, 10 mild BPD, 9 moderate-to-severe BPD) at 36 weeks' postmenstrual age. The fraction of inspired oxygen (F_I O₂ ) was reduced stepwise at 5-min intervals to achieve peripheral SpO₂ between 86% and 95%. The lowest permissible F_I O₂ and SpO₂ were 0.14% and 86%. We recorded SpO₂ , F_I O₂ , and the respiratory signal (respiratory inductive plethysmography). We calculated respiratory rate (RR), tidal volume (V_T ), minute ventilation (V_E ), and respiratory drive (ratio between V_T and inspiratory time, V_T /T_I ). SpO₂ variability was expressed as the interquartile range (IQR).

RESULTS

F_I O₂ was reduced from a median (Q1, Q3) of 0.21 (0.21, 0.21) to 0.17 (0.17, 0.18). We observed a marked individual variability in the ventilatory response to the hypoxic challenge, regardless of BPD severity. At the lowest permissible F_I O₂ , 37 (65%) infants reduced their V_E , and 20 (35%) increased minute ventilation; 20 infants (35%) developed periodic breathing associated with increased SpO₂ IQR and lower SpO₂ minima, and 16 (28%) exhibited an oscillatory pattern in V_E and SpO₂ without end-expiratory pauses, regardless of BPD severity.

CONCLUSION

In very preterm infants, a mild hypoxic challenge reduced ventilation, increased SpO₂ variability and periodic breathing regardless of BPD severity.

Prematurity, the diagnosis of bronchopulmonary dysplasia, and maturation of ventilatory control

Infants born before 32 weeks gestational age and receiving respiratory support at 36 weeks postmenstrual age (PMA) are diagnosed with bronchopulmonary dysplasia (BPD). This label suggests that their need for supplemental oxygen (O₂ ) is primarily due to acquired dysplasia of airways and airspaces, and that the supplemental O₂ is treating residual parenchymal lung disease. However, emerging evidence suggests that immature ventilatory control may also contribute to the need for supplemental O₂ at 36 weeks PMA. In all newborns, maturation of ventilatory control continues ex utero and is a plastic process. Among premature infants, supplemental O₂ mitigates the hypoxemic effects of delayed maturation of ventilatory control, as well as reduces the duration and frequency of periodic breathing events. Nevertheless, prematurity is associated with altered and occasionally aberrant maturation of ventilatory control. Infants born prematurely, with or without a diagnosis of BPD, are more prone to long-lasting effects of dysfunctional ventilatory control. This review addresses normal and abnormal maturation of ventilatory control and suggests how aberrant maturation complicates assigning the diagnosis of BPD. Greater awareness of the interaction between parenchymal lung disease and delayed maturation of ventilatory control is essential to understanding why a given premature infant requires and is benefitting from supplemental O₂ at 36 weeks PMA.