Safety of Bottle-Feeding Under Nasal Respiratory Support in Preterm Lambs With and Without Tachypnoea

Abstract

Aim: Convalescing preterm infants often require non-invasive respiratory support, such as nasal continuous positive airway pressure or high-flow nasal cannulas. One challenging milestone for preterm infants is achieving full oral feeding. Some teams fear nasal respiratory support might disrupt sucking-swallowing-breathing coordination and induce severe cardiorespiratory events. The main objective of this study was to assess the safety of oral feeding of preterm lambs on nasal respiratory support, with or without tachypnoea. Methods: Sucking, swallowing and breathing functions, as well as electrocardiogram, oxygen haemoglobin saturation, arterial blood gases and videofluoroscopic swallowing study were recorded in 15 preterm lambs during bottle-feeding. Four randomly ordered conditions were studied: control, nasal continuous positive airway pressure (6 cmH₂O), high-flow nasal cannulas (7 L•min^-1), and high-flow nasal cannulas at 7 L•min^-1 at a tracheal pressure of 6 cmH₂O. The recordings were repeated on days 7-8 and 13-14 to assess the effect of maturation. Results: None of the respiratory support impaired the safety or efficiency of oral feeding, even with tachypnoea. No respiratory support systematically impacted sucking-swallowing-breathing coordination, with or without tachypnoea. No effect of maturation was found. Conclusion: This translational physiology study, uniquely conducted in a relevant animal model of preterm infant with respiratory impairment, shows that nasal respiratory support does not impact the safety or efficiency of bottle-feeding or sucking-swallowing-breathing coordination. These results suggest that clinical studies on bottle-feeding in preterm infants under nasal continuous positive airway pressure and/or high-flow nasal cannulas can be safely undertaken.

Keywords: lamb; non-invasive respiratory support; oral feeding; preterm; sucking–swallowing–breathing coordination.

FIGURE 1

Safety of bottle-feeding in the three nasal respiratory support conditions studied. Four variables are displayed for each nasal respiratory support to illustrate the absence of significant cardiorespiratory events, with (light grey boxes) and without (dark grey boxes) tachypnoea, on postnatal days 7–8 (A) and 13–14 (B) recordings. Results are presented as median (Q1, Q3); * indicates a statistically significant difference (p < 0.05). For recordings on postnatal days 7–8, nCPAP (n = 14 with and n = 15 without tachypnoea) and HFNCcpap (n = 14 with and n = 15 without tachypnoea) significantly increased minimal HR compared to control (n = 15 with and without tachypnoea), whereas the percentage of HR decrease was lower with HFNC (n = 13 with and n = 14 without tachypnoea). For recordings on postnatal days 13–14, a lower minimal heart rate was observed with HFNC (n = 11 with and without tachypnoea) when compared to nCPAP (n = 9 with and n = 11 without tachypnoea) and HFNCcpap (n = 11 with and without tachypnoea) in the absence of tachypnoea. For postnatal days 13–14, n = 12 with and without tachypnoea in the control condition. CTRL, control condition (no respiratory support); nCPAP, nasal continuous positive airway pressure at 6 cmH₂O; HFNC, high-flow nasal cannula at 7 L•min^–1; HFNCcpap, high-flow nasal cannula at 7 L•min^–1 with end-expiratory tracheal pressure equivalent to nCPAP. The scattered dots represent outlier data points which were included in the analysis.

FIGURE 2

Sucking (SU)–swallowing (SW)–breathing (BR) coordination during bottle-feeding in the three nasal respiratory support conditions studied. Four variables are displayed for each nasal respiratory support to illustrate sucking–swallowing–breathing coordination, with (light grey boxes) and without (dark grey boxes) tachypnoea, on postnatal days 7–8 (A) and 13–14 (B) recordings. Of note, no alterations of SU–SW–BR coordination were observed on postnatal days 7–8. Results are presented as median (Q1, Q3); * indicates a statistically significant difference (p < 0.05). For postnatal days 7–8, control (n = 15 with and without tachypnoea), nCPAP (n = 14 with and n = 15 without tachypnoea), HFNC (n = 13 with and n = 14 without tachypnoea), and HFNCcpap (n = 14 with and n = 15 without tachypnoea). For postnatal days 13–14, control (n = 12 with and without tachypnoea), nCPAP (n = 9 with and n = 11 without tachypnoea), HFNC (n = 11 with and without tachypnoea), and HFNCcpap (n = 11 with and without tachypnoea). Please see Figure 1 for abbreviations. The scattered dots represent outlier data points which were included in the analysis.

FIGURE 3

Efficiency of oral feeding in the three nasal respiratory support conditions studied. Four variables are displayed for each nasal respiratory support to illustrate feeding efficiency, with (light grey boxes) and without (dark grey boxes) tachypnoea, on postnatal days 7–8 (A) and 13–14 (B) recordings. Of note, no efficiency indices were modified by any of the NRS conditions tested on postnatal days 7–8. Results are presented as median (Q1 and Q3); * indicates a statistically significant difference (p < 0.05). See Figure 2 legend for absolute numbers of lambs studied in each experimental condition, and Figure 1 for abbreviations. The scattered dots represent outlier data points which were included in the analysis.