Nasal respiratory support and tachypnea and oral feeding in full-term newborn lambs

Effects of Nasal Respiratory Support on Laryngeal and Esophageal Reflexes in Preterm Lambs

BACKGROUND

Significant cardiorespiratory events can be triggered in preterm infants as part of laryngeal chemoreflexes (LCRs) and esophageal reflexes (ERs). We previously showed that nasal continuous positive airway pressure (nCPAP) blunted the cardiorespiratory inhibition induced with LCRs. Therefore, we aimed to compare the effects of nCPAP and high-flow nasal cannulas (HFNC) on the cardiorespiratory events induced during LCRs and ERs. The hypothesis is that nCPAP but not HFNC decreases the cardiorespiratory inhibition observed during LCRs and ERs.

METHODS

Eleven preterm lambs were instrumented to record respiration, ECG, oxygenation, and states of alertness. LCRs and ERs were induced during non-rapid eye movement sleep in a random order under these conditions: nCPAP 6 cmH2O, HFNC 7 L/min, high-flow nasal cannulas 7 L/min at a tracheal pressure of 6 cmH2O, and no respiratory support.

RESULTS

nCPAP 6 cmH2O decreased the cardiorespiratory inhibition induced with LCRs, but not with ERs in preterm lambs. This blunting effect was less marked with HFNC 7 L/min, even when the tracheal pressure was maintained at 6 cmH2O.

CONCLUSIONS

nCPAP might be a treatment for cardiorespiratory events related to LCRs in newborns, either in the context of laryngopharyngeal refluxes or swallowing immaturity. Our preclinical results merit to be confirmed through clinical studies.

IMPACT

Laryngeal chemoreflexes can be responsible for significant cardiorespiratory inhibition in newborns, especially preterm. Nasal continuous positive airway pressure at 6 cmH2O significantly decreased this cardiorespiratory inhibition. High-flow nasal cannulas at 7 L/min had a lesser effect than nasal continuous positive airway pressure. Esophageal stimulation was responsible for a smaller cardiorespiratory inhibition, which was not significantly modified by nasal continuous positive airway pressure or high-flow nasal cannulas. Nasal continuous positive airway pressure should be tested for its beneficial effect on cardiorespiratory events related to laryngeal chemoreflexes in preterm newborns.

Pharyngeal biorhythms during oral milk challenge in high-risk infants: Do they predict chronic tube feeding?

BACKGROUND

Eating difficulties are common in high-risk neonatal intensive care unit (NICU) infants; mechanisms remain unclear. Crib-side pharyngo-esophageal motility testing is utilized to assess contiguous swallowing physiology, and cross-system interplay with cardio-respiratory rhythms. Aims were to: (1) identify whether distinct pharyngeal rhythms exist during oral milk challenge (OMC), and (2) develop a chronic tube feeding risk prediction model in high-risk infants.

METHODS

Symptomatic NICU infants (N = 56, 29.7 ± 3.7 weeks birth gestation) underwent pharyngo-esophageal manometry with OMC at 40.9 ± 2.5 weeks postmenstrual age (PMA). Exploratory cluster data analysis (partitioning around k-medoids) was performed to identify patient groups using pharyngeal contractile rhythm data (solitary swallows and swallows within bursts). Subsequently, (a) pharyngeal-esophageal, cardio-respiratory, and eating method characteristics were compared among patient groups using linear mixed models, and (b) chronic tube feeding prediction model was created using linear regression.

RESULTS

Three distinct patient groups were identified with validity score of 0.6, and termed sparse (high frequency of solitary swallows), intermediate, or robust (high swallow rate within bursts). Robust group infants had: lesser pharyngeal and esophageal variability, greater deglutition apnea, pharyngeal activity, and esophageal activity (all p < 0.05), but less frequent heart rate decreases (p < 0.05) with improved clinical outcomes (milk transfer rate, p < 0.001, and independent oral feeding at discharge, p < 0.03). Chronic tube feeding risk = -11.37 + (0.22 × PMA) + (-0.73 × bronchopulmonary dysplasia) + (1.46 × intermediate group) + (2.57 × sparse group).

CONCLUSIONS

Robust pharyngeal rhythm may be an ideal neurosensorimotor biomarker of independent oral feeding. Differential maturation of cranial nerve-mediated excitatory and inhibitory components involving foregut, airway, and cardiac rhythms distinguishes the physiologic and pathophysiologic basis of swallowing and cardio-respiratory adaptation.

Nasal continuous positive airway pressure practices in preterm infants: A survey of neonatal providers

BACKGROUND

The standard of care for respiratory support of preterm infants is nasal continuous positive airway pressure (CPAP), yet practices are not standardized. Our aim was to survey CPAP practices in infants < 32 weeks gestation among the American Academy of Pediatrics Neonatal-Perinatal section.

METHODS

A US, web-based survey inquired about the initiation, management, and discontinuation of CPAP, and chinstrap use and oral feedings on CPAP.

RESULTS

857 providers consented. Regarding criteria to discontinue/wean CPAP: 69% use specific respiratory stability criteria; 22% a specific post-menstrual age; 8% responded other. 64% did not have guidelines for CPAP discontinuation; 54% did not have guidelines for CPAP initiation. 66% believe chinstraps improve CPAP efficacy; however, 11% routinely apply a chinstrap. 22% allow oral feeds on CPAP in certain circumstances.

CONCLUSION

There are meaningful variabilities in CPAP practices among neonatal providers across the US. Given the potential long-term implications this can have on the growth and development of the preterm lung, further evidence-based research is needed in relation to respiratory outcomes to optimize and standardize CPAP strategies.

Evidence-Based Approaches to Successful Oral Feeding in Infants with Feeding Difficulties

Infants in the neonatal intensive care unit (NICU) frequently have feeding difficulties with the root cause remaining elusive to identify. Evaluation of the provider/parent/infant feeding process may provide objective clues to sources of feeding difficulty. Specialized testing may be necessary to determine if the infant's swallowing skills are dysfunctional, immature, or maldeveloped, and to determine the risk of feeding failure or chronic tube feeding. Current evidence-based diagnostic and management approaches resulting in successful oral feeding in the NICU infant are discussed.

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

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.