Defining pharyngeal contractile integral during high-resolution manometry in neonates: a neuromotor marker of pharyngeal vigor

Characterization of pharyngeal contractile integral using pharyngeal manometry in children

OBJECTIVES

Pharyngeal contractile integral (PhCI) is the product of mean pharyngeal contractile amplitude, length, and duration, and provides a single metric for the vigor of entire pharyngeal contraction. A major limitation in children is lack of characterization of PhCI on high-resolution pharyngeal manometry. We aimed to determine and compare the values of PhCI in children with the abnormal and normal videofluoroscopic study of swallow (VFSS).

METHODS

Children who underwent high-resolution pharyngeal and esophageal manometry (HRPM/HREM), as well as VFSS, were divided into two groups; "normal VFSS" and "abnormal VFSS" groups. PhCI was calculated from the pharyngo-esophageal manometry analysis software (MMS, v9.5, Laborie Medical Technologies), and compared in these two groups.

RESULTS

Of 67 children, 9 had abnormal VFSS (mean age 64 ± 50 months; 66.7% males), while 58 had normal VFSS (mean age 123 ± 55 months; 47% males). The mean PhCI in abnormal and normal VFSS groups was 82.00 ± 51.90 and 147.28 ± 53.89 mmHg.s.cm, respectively (p = 0.001). Subjects with abnormal VFSS were significantly younger than those with normal VFSS (p = 0.003). However, after adjusting for the VFSS result, age was no longer related to PhCI (p = 0.364). In subgroup analysis of children presenting with dysphagia, the mean PhCI in abnormal (9 subjects) and normal (36 subjects) VFSS groups was 82.00 ± 51.90 and 141.86 ± 50.39 mmHg.s.cm, respectively (p = 0.003).

CONCLUSIONS

PhCI was significantly lower in children with abnormal VFSS than in those with normal VFSS. We did not find a significant impact of age on PhCI in our pediatric populations.

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.

Accuracy of High-Resolution Pharyngeal Manometry Metrics for Predicting Aspiration and Residue in Oropharyngeal Dysphagia Patients with Poor Pharyngeal Contractility

Several physiological metrics can be derived from pharyngeal high-resolution impedance manometry (HRPM), but their clinical relevance has not been well established. We investigated the diagnostic performance of these metrics in relation to videofluoroscopic (VFS) assessment of aspiration and residue in patients with oropharyngeal dysphagia. We analyzed 263 swallows from 72 adult patients (22-91 years) with diverse medical conditions. Metrics of contractility, upper esophageal sphincter (UES) opening and relaxation, flow timing, intrabolus distension pressure, and a global Swallow Risk Index (SRI) were derived from pressure-impedance recordings using pressure-flow analysis. VFS data were independently scored for airway invasion and pharyngeal residue using the Penetration-Aspiration Scale and the Normalized Residue Ratio Scale, respectively. We performed multivariate logistic regression analyses to determine the relationship of HRPM metrics with radiological outcomes and receiver-operating characteristic (ROC) analysis to evaluate their diagnostic accuracy. We identified aspiration in 25% and pharyngeal residue in 84% of the swallows. Aspiration was independently associated with hypopharyngeal peak pressure < 65 mmHg (HypoPeakP) [adjusted odds ratio (OR) 5.27; 95% Confidence Interval (CI) (0.99-28.1); p = 0.051], SRI > 15 [OR 4.37; 95% CI (1.87-10.2); p < 0.001] and proximal esophageal contractile integral (PCI) < 55 mmHg·cm·s [OR 2.30; 95% CI (1.07-4.96); p = 0.034]. Pyriform sinus residue was independently predicted by HypoPeakP < 65 mmHg [OR 7.32; 95% CI (1.93-27.7); p = 0.003], UES integrated relaxation pressure (UES-IRP) > 3 mmHg [OR 2.96; 95% CI (1.49-5.88); p = 0.002], and SRI > 15 [OR 2.17; 95% CI (1.04-4.51); p = 0.039]. Area under ROC curve (AUC) values for individual HRPM metrics ranged from 0.59 to 0.74. Optimal cut-off values were identified. This study demonstrates the diagnostic value of certain proposed and adjunct HRPM metrics for identifying signs of unsafe and inefficient bolus transport in patients with oropharyngeal dysphagia.

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.

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

Videofluoroscopy swallow studies (VFSS) and high-resolution manometry (HRM) methods complement to ascertain mechanisms of infant feeding difficulties. We hypothesized that: (a) an integrated approach (study: parent-preferred feeding therapy based on VFSS and HRM) is superior to the standard-of-care (control: provider-prescribed feeding therapy based on VFSS), and (b) motility characteristics are distinct in infants with penetration or aspiration defined as penetration-aspiration scale (PAS) score ≥ 2. Feeding therapies were nipple flow, fluid thickness, or no modification. Clinical outcomes were oral-feeding success (primary), length of hospital stay and growth velocity. Basal and adaptive HRM motility characteristics were analyzed for study infants. Oral feeding success was 85% [76-94%] in study (N = 60) vs. 63% [50-77%] in control (N = 49), p = 0.008. Hospital-stay and growth velocity did not differ between approaches or PAS ≥ 2 (all P > 0.05). In study infants with PAS ≥ 2, motility metrics differed for increased deglutition apnea during interphase (p = 0.02), symptoms with pharyngeal stimulation (p = 0.02) and decreased distal esophageal contractility (p = 0.004) with barium. In conclusion, an integrated approach with parent-preferred therapy based on mechanistic understanding of VFSS and HRM metrics improves oral feeding outcomes despite the evidence of penetration or aspiration. Implementation of new knowledge of physiology of swallowing and airway protection may be contributory to our findings.

Pharyngoesophageal motility reflex mechanisms in the human neonate: importance of integrative cross-systems physiology

Swallowing is a critical function for survival and development in human neonates and requires cross-system coordination between neurological, airway, and digestive motility systems. Development of pharyngoesophageal motility is influenced by intra- and extrauterine development, pregnancy complications, and neonatal comorbidities. The primary role of these motility reflex mechanisms is to maintain aerodigestive homeostasis under basal and adaptive biological conditions including oral feeding, gastroesophageal reflux, and sleep. Failure may result in feeding difficulties, airway compromise, dysphagia, aspiration syndromes, and chronic eating difficulties requiring prolonged tube feeding. We review the integration of cross-systems physiology to describe the basis for physiological and pathophysiological neonatal aerodigestive functions.

Anemia of Prematurity and Oral Feeding Milestones in Premature Infants

OBJECTIVE

Anemia of prematurity (AOP) and oral feeding problems are common in premature infants. This study aimed to determine the influence of AOP on aerodigestive outcomes and the duration to full Per Oral (PO).

STUDY DESIGN

Prospectively collected data on premature infants who initiated oral feeds at ≤ 34 weeks' postmenstrual age were examined. Infants were categorized into "AOP+" and "AOP-" based on hematocrit at initial PO, that is, < 29 or ≥ 29%.

RESULTS

Forty-four infants in AOP+ compared with 74 in AOP-. AOP+ infants had lower birth gestation and weight (p < 0.001). The anthropometrics at initial PO were similar. AOP+ had lower mean hematocrit and higher oxygen need at initial PO, and at full PO (p < 0.05). AOP+ reached full PO at a later gestation and took longer days from initial PO to full PO (p < 0.01). BPD, intraventricular hemorrhage (IVH ≤ 2), and hospital stay were greater in the AOP+ (p < 0.05). After adjusting for covariates, initial PO hematocrit was not predictive of time to full PO [hazard ratio 1.3 (CI 0.88-2.0), p = 0.18].

CONCLUSION

AOP is not independently associated with the duration to full PO. Supplemental oxygen for associated comorbidities may have compensated for the underlying anemia.

The Emerging Importance of High-Resolution Manometry in the Evaluation and Treatment of Deglutition in Infants, Children, and Adults: New Opportunities for Speech-Language Pathologists

Purpose Diagnostic precision and prolonged testing before, during, and after deglutition is lacking across the age spectrum. Conventional clinical evaluation and radiologic methods are widely used but are reliant on human perception, carrying the risk of subjectivity. High-resolution manometry (HRM) is an emerging clinical and research tool and has the capability to objectively measure the dynamics, kinetics, regulatory, and correlation aspects of deglutition. Method We review the basics of manometry and the methods, metrics, and applications of this technology across the age spectrum. The goal is to aid in the translation of HRM from research tool to clinical use by the speech-language pathologist in the development of better global plans to understand normal and abnormal deglutition. Results HRM is an easily adaptable precise diagnostic tool that can be used to examine deglutition phases and abnormalities across the age spectrum from neonates to nonagenarians and can be a valuable adjunct to specialty evaluation of persistent deglutition disorders. Conclusion New opportunities will emerge upon further research for larger-scale translation once normative data and recognition of biomarkers of abnormality are ascertained.

Feeding and Swallowing Difficulties in Neonates: Developmental Physiology and Pathophysiology

Development of enteral and oral feeding milestones in infants is intricately linked to physiologic maturation of the gastrointestinal tract and its complex interplay with cardiorespiratory and central nervous system control and coordination. Assessment of an infant's developmental skills and maturation can guide us with targeted management approaches and prediction of feeding outcomes. In this article, we review and summarize the developmental aspects of oral feeding and swallowing physiology, and current understanding of the pathophysiological changes associated with feeding difficulties in infants.

Gastroesophageal Reflux Disease in the Neonatal Intensive Care Unit Neonate: Controversies, Current Understanding, and Future Directions

Gastroesophageal reflux (GER) is considered physiologic and is a normal process; whereas, when aerodigestive consequences are associated, it is often interpreted as GER disease (GERD). However, the distinction between them remains a challenge in infants in the NICU. Reflux-type of symptoms are heterogeneous, and often managed with changes in diet, feeding methods, and acid-suppressive therapy; all these empiric therapies lack objectivity; hence, practice variation is universal. We clarify the current controversies, explain the potential role of GERD in causing symptoms and complications, and highlight current advances. The evidence basis for the diagnostic strategies is discussed.

Pharyngeal contractile and regulatory characteristics are distinct during nutritive oral stimulus in preterm-born infants: Implications for clinical and research applications

BACKGROUND

Maturation of pharyngeal swallowing during neonatal oral feeding is unknown. Our objective was to evaluate pharyngeal functioning using high-resolution manometry (HRM) during nutritive oral stimulus and test the hypothesis that pharyngeal contractility and regulation are distinct in preterm-born infants.

METHODS

High-resolution manometry data during oral milk feeding were analyzed for pharyngeal contractile (PhCI, mm Hg cm s) and regulatory (number and frequency of pharyngeal contractions and bursts, pharyngeal activity-to-quiescence ratio, upper esophageal sphincter nadir pressure) characteristics in 23 preterm (<38 weeks' gestation) and 18 full-term-born infants at term maturation. Mixed linear models and stepwise regression methods were used.

RESULTS

Despite more oral feeding experiences (P < 0.05), preterm infants (vs full-term), consumed less milk volume (P < 0.001), had lesser pharyngeal contractions within bursts (P = 0.04), lower pharyngeal contraction frequency (P < 0.01), and lower pharyngeal activity (P = 0.03), but higher PhCI per individual contraction (P = 0.01). PhCI is higher for longer PMA (P < 0.05), higher UES nadir pressures (P < 0.05), and lower pharyngeal contraction frequency (P < 0.05).

CONCLUSIONS

Nutritive oral milk stimulus provoked pharyngeal contractility characteristics is distinct in preterm-born. Despite more oral nutritive experiences, preterm infants had underdeveloped excitatory and inhibitory rhythmic activity. Cranial nerve IX and X effects on sensory-motor responses and feedback (excitation-inhibitory rhythm regulation) remain immature among preterm-born even at full-term maturational status. We speculate the relationship between PhCI and UES regulatory activity contributes to the observed differences in preterm and full-term infants.

High-Resolution Pharyngeal Manometry and Impedance: Protocols and Metrics-Recommendations of a High-Resolution Pharyngeal Manometry International Working Group

High-resolution manometry has traditionally been utilized in gastroenterology diagnostic clinical and research applications. Recently, it is also finding new and important applications in speech pathology and laryngology practices. A High-Resolution Pharyngeal Manometry International Working Group was formed as a grass roots effort to establish a consensus on methodology, protocol, and outcome metrics for high-resolution pharyngeal manometry (HRPM) with consideration of impedance as an adjunct modality. The Working Group undertook three tasks (1) survey what experts were currently doing in their clinical and/or research practice; (2) perform a review of the literature underpinning the value of particular HRPM metrics for understanding swallowing physiology and pathophysiology; and (3) establish a core outcomes set of HRPM metrics via a Delphi consensus process. Expert survey results were used to create a recommended HRPM protocol addressing system configuration, catheter insertion, and bolus administration. Ninety two articles were included in the final literature review resulting in categorization of 22 HRPM-impedance metrics into three classes: pharyngeal lumen occlusive pressures, hypopharyngeal intrabolus pressures, and upper esophageal sphincter (UES) function. A stable Delphi consensus was achieved for 8 HRPM-Impedance metrics: pharyngeal contractile integral (CI), velopharyngeal CI, hypopharyngeal CI, hypopharyngeal pressure at nadir impedance, UES integrated relaxation pressure, relaxation time, and maximum admittance. While some important unanswered questions remain, our work represents the first step in standardization of high-resolution pharyngeal manometry acquisition, measurement, and reporting. This could potentially inform future proposals for an HRPM-based classification system specifically for pharyngeal swallowing disorders.