Mechanisms of bradycardia in premature infants: Aerodigestive–cardiac regulatory–rhythm interactions

Abstract

Objective Eating difficulties coupled with cardiorespiratory spells delay acquisition of feeding milestones in convalescing neonates, and the mechanisms are unclear. Aims were to examine and compare the pharyngoesophageal–cardiorespiratory (PECR) response characteristics: (a) in control neonates and those with recurrent bradycardia spells; and (b) during pharyngeal stimulation when bradycardia occurs versus when no bradycardia occurs. Methods Preterm infants ( N = 40, 27 ± 3 weeks gestation), underwent concurrent pharyngoesophageal manometry, electrocardiography, respiratory inductance plethysmography, and nasal airflow thermistor to evaluate pharyngoesophageal motility, heart rate (HR), and respiration during graded abrupt pharyngeal sterile water stimuli. Infants with recurrent bradycardia ( N = 28) and controls ( N = 12) were evaluated at 38 (38–40) and 39 (38–40) weeks postmenstrual age, respectively. Comparisons were performed (a) between study and control groups; and (b) among HR responses of <80 BPM, 80–100 BPM, and >100 BPM. Results Overall, characteristics of PECR responses in infants with a history of recurrent bradycardia (vs. controls) did not differ ( p > .05). However, when pharyngeal stimulus induced severe bradycardia (<80 BPM): prolonged respiratory rhythm change, increased pharyngeal activity, increased esophageal dysmotility (as evidenced by prolonged esophageal inhibition and motor activity), and prolonged lower esophageal sphincter relaxation were noted (all p < .05). Conclusions In control infants and those with recurrent bradycardia, pharyngeal stimulation results in similar PECR response characteristics. However, when severe bradycardia occurs, PECR response characteristics are distinct. The mechanisms of severe bradycardia spells are related to abnormal prolongation of vagal inhibitory effects on cardiorespiratory rhythms in conjunction with prolonged esophageal inhibition and delays with terminal swallow.

Mechanisms and management considerations of parent-chosen feeding approaches to infants with swallowing difficulties: an observational study

“…Central swallowing mechanisms are hierarchical, and are adaptational; for example, when these mechanisms are dysfunctional (as in the absence of swallowing, poor propagation, or poor coordination) other cascading reflexes are triggered such as coughing or apnea/bradycardia/desaturation events 26 – 28 , 33 , 57 . On the other hand, swallowing is also an important restorative mechanism for cardiorespiratory and aerodigestive homeostasis via effective terminal swallowing 28 , 29 , 33 , 38 , 39 . Thus, what construes as a troublesome symptom (problem) is actually a sign of adaptive skill in ensuring aerodigestive clearance.…”

“…Pharyngeal, esophageal, and respiratory characteristics were analyzed as previously published 18 , 19 , 24 , 25 , 38 . (B) Pharyngeal infusion (adaptive state): aerodigestive responses to pharyngeal stimulus were analyzed as previously published and included global (peristalsis and symptoms) and regional (pharynx, UES, esophagus, respiratory) characteristics 24 , 25 , 29 , 38 , 39 , 41 , 42 , 47 , 52 . (C) Oral feeding with milk and barium sulfate (adaptive state): Pharyngeal and esophageal characteristics were measured during oral feeding sessions 24 , 25 .…”

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

“…The catheter was placed nasally by the study physician using the pull through technique and secured 27 . Concurrent nasal airflow thermistor (Integra Life Sciences) was utilized to detect respiratory changes and deglutition apnea (DA) events, and electrocardiography was utilized to monitor heart rate changes 10–14,26,28 . The OMC was recorded concurrently via a video camera (Handycam DCR‐SX45; Sony) mounted to the infant's crib and connected to the manometry system's video recording unit (Vid 410 Matrox Morphis, Laborie Medical Technologies) 29 .…”

“…Automated algorithms were further adapted to detect esophageal and respiratory changes during OMC (Figure 1). Heart rate changes were analyzed utilizing VivoSense Data Analysis Software (v. 3.6; Vivonoetics) 13,28 . Cross‐system coordination between cardio‐respiratory and foregut systems were analyzed by examining ratios between interactive elements.…”

Precision caffeine therapy for apnea of prematurity and circadian rhythms: New possibilities open up

“…In addition, the well-developed laryngeal reflexes and coordination of pharyngoesophageal-cardiorespiratory (PECR) responses are essential for the development and maintenance of cardiorespiratory rhythms ( Gewolb and Vice, 2006 ; Hasenstab-Kenney et al, 2020 ). As shown in Table 2 , pharyngeal stimulations cause a decrease of heart rate in premature infants with uncoordinated suck-swallow-respiration rhythms due to the immature laryngeal reflexes and PECR responses, which would aggravate the disturbance of cardiac and respiratory rhythms ( Hasenstab et al, 2019 ; Hasenstab-Kenney et al, 2020 ). ( Gewolb et al, 2001 ; Gewolb and Vice, 2006 ) found that the development and establishment of suck-swallow rhythms were associated with their PMA.…”