Preterm infants with respiratory distress frequently manifest thoraco-abdominal asynchrony (TAA). This paradoxical breathing pattern, characterized by chestwall retractions, can be improved by continuous distending pressure. The application of continuous positive distending pressure via nasal prongs can be a demanding technical challenge. Excessive positive distending pressure can impair venous return to the heart.
Objective: To determine if paradoxical breathing and ventilation in newborn infants with chest wall retractions, could be improved by external stabilization of the chest wall with a simple brace. The brace encircles the chest attaching by Velcro® to protective skin coverings over the lower half of the sternum and over the back. It provides a continuous outward pull on the chest wall exerting negative distending pressure to the lungs.
Methods: Eight newborn infants (2-85d) who retracted during inspiration were studied. Five breathed spontaneously without CPAP support. Three were intubated and ventilated between 10-20br/min. The intubated patients were supported with 5cmH2O PEEP. Inductance plethysmography was used to measure the percent changes in TAA (measured by:% of inspiration during which the chest moved inwards, the phase angle between chest and abdominal movement, and changes in chest wall displacement. For the 3 ventilated patients we also used a whole body plethysmograph (Vitaltrends, VT1000) to non-invasively and continuously measure pulmonary function (PF), including: minute ventilation, tidal volume (VT), spontaneous tidal volume and inspiratory time (TI). We calculated the ratio of VT/TI as an index of breathing efficiency. Breaths from 10-20min epochs in the supine position were analyzed first without, then with the chest brace applied.
Results: In 4 of 5 non-intubated patients the chest brace significantly improved all measures of TAA by >40% (p <0.0001). In 2/3 intubated patients the chest brace also produced >50% improvement in all indices of TAA. This was accompanied by >30%improvement in PF including: minute ventilation, VT/TI, and spontaneous tidal volume (p<0.0001)
Conclusion: This study shows that thoraco-abdominal asynchrony and pulmonary function in preterm infants can be improved with mechanical stabilization of the chest wall.
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Funded by NIH STTR grant HL56435 to MEDELEX,inc.
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Palmer, C., Korten, J., Darrow, K. et al. Mechanical Stabilization of the Chest Wall in Preterm Infants improves Pulmonary Mechanics † 1714. Pediatr Res 43 (Suppl 4), 292 (1998). https://doi.org/10.1203/00006450-199804001-01736
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DOI: https://doi.org/10.1203/00006450-199804001-01736