Alae Nasi Activation in Preterm Infants during Oral Feeding


ABSTRACT: Preterm infants may demonstrate impaired ventilation during oral feeding with resultant hypoxemia and hypercarbia. This study was designed to determine whether infants activate a representative upper airway muscle, the ala nasi, in response to these ventilatory changes. Ten preterm infants (postconceptional age at study 35 ± 4 wk, weight 2.2 ± 0.1 kg) were studied during a control period, continuous feeding, subsequent intermittent feeding, and a period of nonnutritive sucking. Nasal airflow was measured with a pneumotachometer to quantify minute ventilation. The alae nasi electromyogram (EMGAN) was recorded with surface electrodes, and sucking pressure was detected by a catheter in the feeding nipple. End-tidal CO2 and O2 saturation were also recorded during each period. The percentage of breaths associated with EMGAN activity increased from 41 ± 13% during the control period to 95 ± 5% and 93 ± 7% during continuous and intermittent sucking, respectively (p < 0.05). Eighty-seven ± 5% of EMGAN activity occurred during inspiration. During continuous and intermittent sucking, the amplitude of EMGAN activity also increased (6.8 ± 5.2 and 6.7 ± 4.0 arbitrary units/breath, respectively) compared with the control period (2.4 ± 2.8 units/breath, p < 0.05). In association with the increase in EMGAN activity, O2 saturation fell from 98 ± 1% in the control period to 95 ± 1% during both continuous and intermittent feeding (p < 0.05), and minute ventilation fell from 274 ± 80 mL/min/kg during the control period to 190 ± 81 and 208 ± 57 mL/min/kg during continuous and intermittent feeding, respectively (p < 0.05). We conclude that the preterm infant is able to activate the alae nasi while feeding. We speculate that activation of the upper airway muscles may contribute to reduction in upper airway resistance during feeding.

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Correspondence to Martha J Miller.

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