Reflexes that impact spontaneous breathing of preterm infants at birth: a narrative review

Abstract

Some neural circuits within infants are not fully developed at birth, especially in preterm infants. Therefore, it is unclear whether reflexes that affect breathing may or may not be activated during the neonatal stabilisation at birth. Both sensory reflexes (eg, tactile stimulation) and non-invasive ventilation (NIV) can promote spontaneous breathing at birth, but the application of NIV can also compromise breathing by inducing facial reflexes that inhibit spontaneous breathing. Applying an interface could provoke the trigeminocardiac reflex (TCR) by stimulating the trigeminal nerve resulting in apnoea and a reduction in heart rate. Similarly, airflow within the nasopharynx can elicit the TCR and/or laryngeal chemoreflex (LCR), resulting in glottal closure and ineffective ventilation, whereas providing pressure via inflations could stimulate multiple receptors that affect breathing. Stimulating the fast adapting pulmonary receptors may activate Head’s paradoxical reflex to stimulate spontaneous breathing. In contrast, stimulating the slow adapting pulmonary receptors or laryngeal receptors could induce the Hering-Breuer inflation reflex or LCR, respectively, and thereby inhibit spontaneous breathing. As clinicians are most often unaware that starting primary care might affect the breathing they intend to support, this narrative review summarises the currently available evidence on (vagally mediated) reflexes that might promote or inhibit spontaneous breathing at birth.

Aerosol drug delivery to spontaneously-breathing preterm neonates: lessons learned

“…Infants born at an early GA have structurally and functionally immature lungs and can be classified according to their ability to breathe spontaneously, which is a major determinant of the level of the required respiratory support. Spontaneous breathing depends on not only lung maturation, but also on the developmental status of the central nervous system and its ability to manage the respiratory drive and the control of respiratory muscles [2,3].…”

“…Intrinsic and extrinsic factors influencing aerosol drug delivery in premature infants. The figure depicts two possible scenarios: (1) nebulizer positioned in the inspiratory limb of a standard constant flow ventilator (top); this nebulizer positioning could also be applied to bubble Continuous Positive Airway Pressure (CPAP) and variable flow drivers, and to High Flow Nasal Cannula (HFNC);(2) nebulizer positioned between the Y piece and the patient interface in a standard constant flow ventilator (bottom); this nebulizer positioning could be compatible with bubble CPAP but not with variable flow drivers nor HFNC…”

Effects of Early Respiratory Physiotherapy on Spontaneous Respiratory Activity of Preterm Infants: Study Protocol for a Randomized Controlled Trial

“…Te Pas et al observed a positive effect of the use of repetitive tactile stimulation on respiratory effort and oxygenation of preterm infants at birth (3): rubbing the sole of the foot or the infants'back supposedly activates proprioceptors or somatic/visceral mechanoreceptors in the thorax, respectively, which are known to stimulate spontaneous breathing (3). These afferent somatosensory pathways are functional even before 25 weeks of gestation (4,5). To best of our knowledge, no randomized clinical trials have evaluated the e cacy of early and continued respiratory facilitation physiotherapy in avoiding or reducing the need for invasive respiratory support of preterm infants in NICU.…”

Effects of early respiratory physiotherapy on spontaneous respiratory activity of preterm infants: study protocol for a randomized controlled trial

“…Te Pas et al observed a positive effect of the use of repetitive tactile stimulation on respiratory effort and oxygenation of preterm infants at birth [ 3 ]: rubbing the sole of the foot or the infants’ back supposedly activates proprioceptors or somatic/visceral mechanoreceptors in the thorax, respectively, which are known to stimulate spontaneous breathing [ 3 ]. These afferent somatosensory pathways are functional even before 25 weeks of gestation [ 4 , 5 ]. To best of our knowledge, no randomized clinical trials have evaluated the efficacy of early and continued respiratory facilitation physiotherapy in avoiding or reducing the need for invasive respiratory support of preterm infants in NICU.…”