Pressure-flow characteristics of normal and disordered esophageal motor patterns

The Utility of Functional Luminal Imaging Probes Measurements to Diagnose Dysmotility and Their Relationship to Impaired Bolus Clearance

BACKGROUND

Functional luminal imaging probes (FLIP) have been used by multiple centers to assess esophagogastric junction (EGJ) function in patients at risk for esophageal obstruction but its role in diagnosing peristaltic disorders is less well studied. In particular, there are no studies comparing the sensitivity of FLIP to diagnose motility abnormalities and impaired bolus transit by high-resolution esophageal manometry with impedance.

METHODS

We prospectively recruited 42 patients undergoing high-resolution esophageal manometry with impedance (HRIM) who also underwent FLIP between 2018 and 2020. HRIM parameters were analyzed using Swallow Gateway software to determine peristaltic and lower esophageal sphincter pressure measurements as well as bolus flow parameters. FLIP tracings were analyzed for the presence of repetitive antegrade contractions (RACs), EGJ distensibility, and associated parameters.

RESULTS

Forty-two patients were included (11 controls, 7 achalasia, 16 fundoplication, 8 dysmotility). The mean age of patients was 10.1 ± 0.9 years. There were significant differences in bolus flow parameters across diagnosis with longer bolus presence (BPT) in control patients compared with fundoplication and dysmotility patients. There was a significant correlation between EGJ diameter, EGJ distensibility and bolus flow time (BFT) for solid foods (r2 > 0.518, P < 0.02). The presence of RACs and EGJ relaxation during RACs was associated with a greater BFT and BPT across textures (P < 0.05). Forty-two percentage of patients with absent RACs, however, had clear peristalsis by HRIM.

CONCLUSIONS

The presence of RACs and EGJ relaxation by FLIP correlate with improved bolus flow. Patients with an absence of RACs need HRIM to confirm any diagnoses of dysmotility.

Characterizing Esophageal Motility in Neonatal Intensive Care Unit Patients Using High Resolution Manometry

OBJECTIVE

To characterize esophageal motility and esophago-gastric junction (EGJ) function during feeding in neonatal intensive care unit (NICU) patients.

PATIENTS AND METHODS

High resolution manometry with impedance (HRIM) was used to investigate esophageal motility and EGJ function in patients admitted to the NICU. Twenty-eight preterm born infants with bronchopulmonary dysplasia (BPD), 12 born with isolated congenital diaphragmatic hernia (iCDH), and 10 with esophageal atresia (EA) were included. Thirteen healthy infants were included as controls. Esophageal motility and EGJ function were analyzed using objective esophageal bolus transport parameters.

RESULTS

Normal esophageal peristaltic wave patterns were observed in all investigated infants without EA. Nine of 10 patients with EA presented with abnormal esophageal motor wave patterns. A total of 224 nutritive swallows were analyzed (controls, n = 48; BPD, n = 96; iCDH, n = 60; EA, n = 20). Infants with BPD and iCDH had similar distal contractile strength (DCI) compared to healthy controls, while in patients with EA, DCI was significantly lower (Kruskal-Wallis test, p = 0.001). In most infants, EGJ relaxation after swallowing was unaffected. EGJ barrier function, in terms of EGJ-contractile integral, also appeared well-developed and did not differ significantly among patient groups.

CONCLUSIONS

We conclude that esophageal motility studies using pressure-impedance analysis are feasible in young infants. Bolus transport mechanisms following nutritive swallows appeared well-established in all investigated infants with the exception of those with EA. EGJ relaxation was also functional after deglutition and EGJ function as an anti-reflux barrier appeared well-developed in all investigated NICU groups.

What is the role of high-resolution oesophageal manometry in paediatrics?

Abnormal oesophageal motility may impair oesophageal bolus transport leading to symptoms of chest pain and regurgitation. Oesophageal pathophysiology may include neuromuscular and/or structural defects leading to weak, incoordinate or absent peristalsis and impaired oesophago-gastric junction relaxation. Understanding these mechanisms is important to determine the appropriate course of therapy. Whilst, barium oesophagram is the mainstay for clinical investigation of oesophageal motility, high-resolution manometry is now more widely available. This review describes the potential value of high-resolution manometry in paediatric gastroenterology practise.

Pressure-impedance analysis: Assist the diagnosis and classification of ineffective esophageal motility disorder

BACKGROUND AND AIM

We elucidated the clinical significance of distal contractile integral-to-esophageal impedance integral (EII) ratio (DCIIR) in ineffective esophageal motility (IEM) adult patients.

METHODS

We recruited 101 patients with IEM (48.38 ± 1.58 years) and 42 matched healthy volunteers (44.28 ± 1.85 years) in this case-control study. All subjects underwent esophageal high-resolution impedance manometry from October 2014 to May 2018. The diagnosis of IEM was based on the Chicago Classification version 3.0. The EII, EII ratio, and DCIIR were analyzed by matlab software.

RESULTS

The EII, EII ratio, and DCIIR calculated at an impedance threshold of 1500 Ω (EII1500, EII ratio1500, and DCIIR1500, respectively) were significantly lower in the IEM group than in healthy controls (P < 0.0001, < 0.0001, and < 0.0001, respectively). Receiver operating characteristic analysis showed that DCIIR1500 < 0.008 mmHg/Ω, EII1500 > 71 000 Ω.s.cm, and EII ratio1500 > 0.43 were all predictive of IEM. Only DCIIR1500 < 0.008 mmHg/Ω remained significant in diagnosing IEM in the multivariate logistic regression analysis (odds ratio = 72.13, P < 0.001). The DCIIR1500 is negatively correlated with Eckardt score and the Reflux Disease Questionnaire (correlation coefficient = -0.2844 and -0.3136; P = 0.0006 and 0.0002, respectively). Receiver operating characteristic analysis further showed that a DCIIR1500 cut-off of 0.002 mmHg/Ω achieved the best differentiation between the IEM-alternans and IEM-persistens subtypes among IEM patients (P < 0.001).

CONCLUSIONS

The novel pressure-impedance parameter of high-resolution impedance manometry, DCIIR1500, may assist in the diagnosis and classification of IEM and correlated with clinical symptoms.

Twenty years of quantitative instrumental measures of swallowing in children: a systematic review

Early identification and intervention has shown better health outcomes for children with dysphagia. Instrumental swallowing assessments are vital and have been a focus of dysphagia research in the last two decades. This systematic review explores published quantitative instrumental measures of swallowing in children. Five subject-related databases were searched to identify original scientific articles published in English, using instrumental quantitative measures of swallowing to study swallowing/feeding mechanism in children since 1998. Two thousand two hundred and two articles were found from the initial database search and 36 were included in the final qualitative synthesis following PRISMA guidelines. Selected studies showed great diversity in target population, phase/s of swallowing studied, instrumentation used (n = 10) and quantitative measures reported (n = 144). Videofluoroscopy and manometry have been studied most repeatedly. With less frequency, a variety of other instruments has been used to describe suck-swallow patterns and swallowing-related respiration. High-resolution manometry shows the greatest increase in publications with validated, reliable quantitative measures of pharyngeal and oesophageal pressures and timing. More recently, quantification of videofluoroscopy analysis has been a focus.Conclusion: A diverse range of quantitative measures of swallowing is available for children in the literature. However, further reliability and validity testing is needed. Opportunities for clinical application of these quantitative manometric and videofluoroscopic measures are restricted by limited normative comparisons and vast variability in published measures.What is known?• Instrumental swallowing assessments are reliable and accurate in diagnosing swallowing difficulties in children.• However, subjective interpretation of observational findings often questions the optimal use of instrumentation.What is new?• High-resolution manometry has shown promising progress with the development of quantitative objective swallow measures for children. While attempts to quantify video-fluoroscopic measures have been increased in the recent past.• A vast variety of instruments has been used to obtain quantitative and/or objective swallow measures of children, yet clinical application is still in progress.

High-resolution esophageal manometry in pediatrics: Effect of esophageal length on diagnostic measures

BACKGROUND

High-resolution esophageal manometry (HREM), derived esophageal pressure topography metrics (EPT), integrated relaxation pressure (IRP), and distal latency (DL) are influenced by age and size. Combined pressure and intraluminal impedance also allow derivation of metrics that define distension pressure and bolus flow timing. We prospectively investigated the effects of esophageal length on these metrics to determine whether adjustment strategies are required for children.

METHODS

Fifty-five children (12.3 ± 4.5 years) referred for HREM, and 30 healthy adult volunteers (46.9 ± 3.8 years) were included. Studies were performed using the MMS system and a standardized protocol including 10 × 5 mL thin liquid bolus swallows (SBM kit, Trisco Foods) and analyzed via Swallow Gateway (www.swallowgateway.com). Esophageal distension pressures and swallow latencies were determined in addition to EGJ resting pressure and standard EPT metrics. Effects of esophageal length were examined using partial correlation, correcting for age. Adult-derived upper limits were adjusted for length using the slopes of the identified linear equations.

KEY RESULTS

Mean esophageal length in children was 16.8 ± 2.8 cm and correlated significantly with age (r = 0.787, P = .000). Shorter length correlated with higher EGJ resting pressure and 4-s integrated relaxation pressures (IRP), distension pressures, and shorter contraction latencies. Ten patients had an IRP above the adult upper limit. Adjustment for esophageal length reduced the number of patients with elevated IRP to three.

CONCLUSIONS & INFERENCES

We prospectively confirmed that certain EPT metrics, as well as potential useful adjunct pressure-impedance measures such as distension pressure, are substantially influenced by esophageal length and require adjusted diagnostic thresholds specifically for children.

Upper Gastrointestinal Function in Morbidly Obese Adolescents Before and 6 Months After Gastric Banding

BACKGROUND

The effects of laparoscopic adjustable gastric band (LAGB) placement on upper gastrointestinal tract function in obese adolescents are unknown. Therefore, our aim was to determine the short-term effects of LAGB on esophageal motility, gastroesophageal reflux, gastric emptying, appetite-regulatory hormones, and perceptions of post-prandial hunger and fullness.

METHODS

This study was part of a prospective cohort study (March 2009-December 2015) in one tertiary referral hospital. The study included obese adolescents (14-18 years) with a body mass index (BMI) > 40 (or ≥ 35 with comorbidities). Gastric emptying was assessed by ¹³C-octanoic acid breath test, pharyngeal, and esophageal motor function by high-resolution manometry with impedance (HRIM), and appetite and other perceptions using 100-mm visual analogue scales. Dysphagia symptoms were scored using a Dakkak questionnaire. Data were compared pre- and post-LAGB placement and at a 6-month follow-up.

RESULTS

Based upon analysis of 15 adolescents, at the 6-month follow-up, LAGB placement: (i) led to a significant reduction in weight and BMI; (ii) increased fullness and decreased hunger post-meal; (iii) increased symptoms of dysphagia after solid food; and, despite these effects, (iv) caused little or no changes to appetite hormones, while (v) effects on gastric emptying, esophageal motility, esophageal bolus transport, and esophageal emptying were not significant.

CONCLUSION

In adolescents, LAGB improved BMI and altered the sensitivity to nutrients without significant effects on upper gastrointestinal tract physiology at the 6-month follow-up.

Oesophageal atresia

Oesophageal atresia (EA) is a congenital abnormality of the oesophagus that is caused by incomplete embryonic compartmentalization of the foregut. EA commonly occurs with a tracheo-oesophageal fistula (TEF). Associated birth defects or anomalies, such as VACTERL association, trisomy 18 or 21 and CHARGE syndrome, occur in the majority of patients born with EA. Although several studies have revealed signalling pathways and genes potentially involved in the development of EA, our understanding of the pathophysiology of EA lags behind the improvements in surgical and clinical care of patients born with this anomaly. EA is treated surgically to restore the oesophageal interruption and, if present, ligate and divide the TEF. Survival is now ~90% in those born with EA with severe associated anomalies and even higher in those born with EA alone. Despite these achievements, long-term gastrointestinal and respiratory complications and comorbidities in patients born with EA are common and lead to decreased quality of life. Oesophageal motility disorders are probably ubiquitous in patients after undergoing EA repair and often underlie these complications and comorbidities. The implementation of several new diagnostic and screening tools in clinical care, including high-resolution impedance manometry, pH-multichannel intraluminal impedance testing and disease-specific quality of life questionnaires now provide better insight into these problems and may contribute to better long-term outcomes in the future.

High-resolution impedance manometry parameters in the evaluation of esophageal function of non-obstructive dysphagia patients

BACKGROUND

High-resolution impedance manometry (HRIM) allows evaluation of esophageal bolus retention, flow, and pressurization. We explored novel HRIM measures and assessed their temporal relationship to dysphagia symptoms for boluses of different volume and consistency in non-obstructive dysphagia (NOD) patients.

METHODS

Thirty-three NOD patients (n = 19 minor or no disorder of peristalsis ("Normal") and n = 14 esophagogastric junction outflow obstruction ("EGJOO")) were evaluated with HRIM. Patients were administered 5 and 10 mL liquid, semisolid, and 2 and 4 cm solid boluses and indicated bolus perception during individual swallows using a 5-point Likert scale. HRIM was analyzed to assess Chicago Classification and pressure flow metrics, esophageal impedance integral (EII) ratio, and bolus flow time (BFT).

KEY RESULTS

Overall, bolus perception increased with increasing bolus consistency (P < 0.001), but did not differ significantly between EGJOO and Normal patients. EGJOO patients had higher IRP4, higher levels of bolus residual (ie, EII ratio and IR), and restricted esophageal emptying. The results for linking semisolid bolus perception to semisolid-derived measures revealed more biomechanically plausible and consistent patterns when compared to those derived for liquid boluses. In Normal patients, perception of boluses of heavier viscosity was related to higher bolus flow resistance during transport, whilst in EGJOO, perception was related to restriction of esophageal emptying.

CONCLUSION & INFERENCES

These novel pressure-impedance measures may aid in the evaluation of NOD patients by revealing abnormal motor patterns, which may explain symptom generation. Future studies are needed to evaluate which of these measures are worthy of calculation and to establish protocol settings that allow for their meaningful interpretation.

Distal contractile to impedance integral ratio assist the diagnosis of pediatric ineffective esophageal motility disorder

OBJECTIVES

We investigated the diagnostic utility of distal contractile integral (DCI) to esophageal impedance integral (EII) ratio (DCIIR) in high-resolution impedance manometry (HRIM) of ineffective esophageal motility (IEM) in children.

METHODS

We performed HRIM in 31 children with dysphagia, odynophagia, chronic vomiting, chest pain, or heartburn sensation. Based on the Chicago classification version 3.0, 20 subjects were diagnosed with IEM, and 11 subjects were normal. We analyzed the EII and DCIIR using MATLAB software.

RESULTS

The DCIIR calculated at the impedance cutoff at 1500 Ω (DCIIR1500) were significantly lower in IEM group than patients with normal motility (P = 0.007). Receiver operating characteristic (ROC) curve analysis showed that a DCIIR1500 < 0.009 mmHg/Ω best predicted IEM in children (P < 0.001). A DCIIR1500 < 0.008 mmHg/Ω is associated with significant body weight loss > 10% within 6 months in children. (P < 0.001).

CONCLUSIONS

The calculation of DCIIR1500 may assist the automatic analysis of bolus transit in HRIM study to diagnose IEM in children. An DCIIR1500 < 0.009 mmHg/Ω may assist in the diagnosis of IEM in children, and DCIIR1500 < 0.008 mmHg/Ω correlated with significant body weight loss. The calculation of DCIIR may serve as possible parameters for HRIM.

A study of dysphagia symptoms and esophageal body function in children undergoing anti-reflux surgery

BACKGROUND

The role of high-resolution esophageal impedance manometry (HRIM) for establishing risk for dysphagia after anti-reflux surgery is unclear. We conducted a prospective study of children with primary gastroesophageal reflux (GER) disease, for whom symptoms of dysphagia were determined pre-operatively and then post-operatively and we examined for features that may predict post-operative dysphagia.

METHODS

Thirteen children (aged 6.8-15.5 years) undergoing work-up prior to 360o Nissen fundoplication were included in the study. A dysphagia score assessed symptoms at pre-operative study and post-operatively (mean 1.4 years). A HRIM procedure recorded 5-ml liquid, 5-ml viscous and 2-cm solid boluses. We assessed esophageal motility, esophago-gastric junction (EGJ) morphology, EGJ contractility and pressure-flow variables indicative of bolus distension pressures and bolus clearance pressures. A composite pressure-flow index score was also derived.

RESULTS

Pre-operative pressure-flow index was positively correlated with post-operative dysphagia score (viscous bolus r = 0.771, p < 0.005). Of three variables that comprise the pressure-flow index, the ramp pressure measured during bolus clearance was the main driver of the effect seen (viscous bolus r = 0.819, p < 0.005).

CONCLUSIONS

In order to mitigate symptoms in relation to anti-reflux surgery, dysphagia symptoms and esophageal function need to be pre-operatively assessed. In patients with normal motility, an elevated pressure-flow index may predict post-operative dysphagia.

An ANMS-NASPGHAN consensus document on esophageal and antroduodenal manometry in children

BACKGROUND

Upper gastrointestinal symptoms in children are common and motility disorders are considered in the differential diagnosis. High resolution esophageal manometry (HRM) has revolutionized the study of esophageal physiology, and the addition of impedance has provided new insights into esophageal function. Antroduodenal motility has provided insight into gastric and small bowel function.

PURPOSE

This review highlights some of the recent advances in pediatric esophageal and antroduodenal motility testing including indications, preparation, performance, and interpretation of the tests. This update is the second part of a two part series on manometry studies in children (first part was on anorectal and colonic manometry [Neurogastroenterol Motil. 2016;29:e12944]), and has been endorsed by the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) and the American Neurogastroenterology and Motility Society (ANMS).

Novel Pressure-Impedance Parameters for Evaluating Esophageal Function in Pediatric Achalasia

OBJECTIVE

In achalasia, absent peristalsis and reduced esophagogastric junction (EGJ) relaxation and compliance underlie dysphagia symptoms. Novel high-resolution impedance manometry variables, that is, bolus presence time (BPT) and trans-EGJ-bolus flow time (BFT) have been developed to estimate the duration of EGJ opening and trans-EGJ bolus flow. The aim of this study was to evaluate esophageal motor function and bolus flow in children diagnosed with achalasia using these variables.

METHODS

High-resolution impedance manometry recordings from 20 children who fulfilled the Chicago Classification (V3) criteria for achalasia were compared with recordings of 15 children with normal esophageal high-resolution manometry findings and no other evidence suggestive of achalasia. Matlab-based analysis software was used to calculate BPT and BFT.

RESULTS

Both BPT and BFT were significantly reduced in achalasia patients compared with children with normal esophageal motility (BPT 3.3 s vs 5.1 s P < 0.01; BFT 1.4 s vs 4.3 s P < 0.001). BFT was significantly lower than BPT (achalasia difference 1.9 s ± 1.3 s, P = 0.001 and normal difference 0.9 ± 0.3 s, P = 0.001). Overall, there was a significant correlation between BPT and BFT (r = 0.825, P < 0.001). We observed a 2-way differentiation of achalasia patients; those in whom the BPT and BFT were proportional, but significantly lower than in patients with normal peristalsis, and those in whom BFT was disproportionately lower than BPT.

CONCLUSIONS

Calculation of BPT and BFT may help determine whether esophageal bolus transport to the EGJ and/or esophageal emptying through the EGJ are aberrant. For achalasia, this may detect flow resistance at the EGJ, potentially improving both diagnosis and objective assessment of therapeutic effects.

High-resolution impedance manometry parameters enhance the esophageal motility evaluation in non-obstructive dysphagia patients without a major Chicago Classification motility disorder

BACKGROUND

High-resolution impedance manometry (HRIM) allows evaluation of esophageal bolus retention, flow, and pressurization. We aimed to perform a collaborative analysis of HRIM metrics to evaluate patients with non-obstructive dysphagia.

METHODS

Fourteen asymptomatic controls (58% female; ages 20-50) and 41 patients (63% female; ages 24-82), 18 evaluated for dysphagia and 23 for reflux (non-dysphagia patients), with esophageal motility diagnoses of normal motility or ineffective esophageal motility, were evaluated with HRIM and a global dysphagia symptom score (Brief Esophageal Dysphagia Questionnaire). HRIM was analyzed to assess Chicago Classification metrics, automated pressure-flow metrics, the esophageal impedance integral (EII) ratio, and the bolus flow time (BFT).

KEY RESULTS

Significant symptom-metric correlations were detected only with basal EGJ pressure, EII ratio, and BFT. The EII ratio, BFT, and impedance ratio differed between controls and dysphagia patients, while the EII ratio in the upright position was the only measure that differentiated dysphagia from non-dysphagia patients.

CONCLUSIONS & INFERENCES

The EII ratio and BFT appear to offer an improved diagnostic evaluation in patients with non-obstructive dysphagia without a major esophageal motility disorder. Bolus retention as measured with the EII ratio appears to carry the strongest association with dysphagia, and thus may aid in the characterization of symptomatic patients with otherwise normal manometry.

Advances with Neonatal Aerodigestive Science in the Pursuit of Safe Swallowing in Infants: Invited Review

Feeding, swallowing, and airway protection are three distinct entities. Feeding involves a process of sequential, neurosensory, and neuromotor interactions of reflexes and behaviors facilitating ingestion. Swallowing involves anterograde bolus movement during oral-, pharyngeal-, and esophageal phases of peristalsis into stomach. During these events, coordination with airway protection is vital for homeostasis in clearing any material away from airway vicinity. Neurological-airway-digestive inter-relationships are critical to the continuum of successful feeding patterns during infancy, either in health or disease. Neonatal feeding difficulties encompass a heterogeneous group of neurological, pulmonary, and aerodigestive disorders that present with multiple signs posing as clinical conundrums. Significant research breakthroughs permitted understanding of vagal neural pathways and functional aerodigestive connectivity involved in regulating swallowing and aerodigestive functions either directly or indirectly by influencing the supra-nuclear regulatory centers and peripheral effector organs. These neurosensory and neuromotor pathways are influenced by pathologies during perinatal events, prematurity, inflammatory states, and coexisting medical and surgical conditions. Approaches to clarify pathophysiologic mapping of aerodigestive interactions, as well as translating these discoveries into the development of personalized and simplified feeding strategies to advance child health are discussed in this review article.

The Potential Benefits of Applying Recent Advances in Esophageal Motility Testing in Patients with Esophageal Atresia

Infants and children with esophageal atresia commonly present with swallowing dysfunction or dysphagia. Dysphagia can lead to a range of significant consequences such as aspiration pneumonia, malnutrition, dehydration, and food impaction. To improve oral intake, the clinical diagnosis of dysphagia in patients with esophageal atresia should focus on both the pharynx and the esophagus. To characterize the complex interactions of bolus flow and motor function between mouth, pharynx, and esophagus, a detailed understanding of normal and abnormal deglutition is required through the use of adequate and objective assessment techniques. As clinical symptoms do not correlate well with conventional assessment methods of motor function such as radiology or manometry but do correlate with bolus flow, the current state-of-the-art diagnosis involves high-resolution manometry combined with impedance measurements to characterize the interplay between esophageal motor function and bolus clearance. Using a novel pressure flow analysis (PFA) method as an integrated analysis method of manometric and impedance measurements, differentiation of patients with impaired esophago-gastric junction relaxation from patients with bolus outflow disorders is clinically relevant. In this, pressure flow matrix categorizing the quantitative PFA measures may be used to make rational therapeutic decisions in patients with esophageal atresia. Through more advanced diagnostics, improved understanding of pathophysiology may improve our patient care by directly targeting the failed biomechanics of both the pharynx and the esophagus.

Development of Suck and Swallow Mechanisms in Infants

Preterm infants' hospital discharge is often delayed due to their inability to feed by mouth safely and competently. No evidence-based supported guidelines are currently available for health-care professionals caring for these infants. Available interventions advocating benefits are not readily acknowledged for lack of rigorous documentation inasmuch as any improvements may ensue from infants' normal maturation. Through research, a growing understanding of the development of nutritive sucking skills has emerged, shedding light on how and why infants may encounter oral feeding difficulties due to the immaturity of specific physiologic functions. Unfortunately, this knowledge has yet to be translated to the clinical practice to improve the diagnoses of oral feeding problems through the development of relevant assessment tools and to enhance infants' oral feeding skills through the development of efficacious preventive and therapeutic interventions. This review focuses on the maturation of the various physiologic functions implicated in the transport of a bolus from the oral cavity to the stomach. Although infants' readiness for oral feeding is deemed attained when suck, swallow, and respiration are coordinated, we do not have a clear definition of what coordination implies. We have learned that each of these functions encompasses a number of elements that mature at different times and rates. Consequently, it would appear that the proper functioning of sucking, the swallow processing, and respiration need to occur at two levels: first, the elements within each function must reach an appropriate functional maturation that can work in synchrony with each other to generate an appropriate suck, swallow process, and respiration; and second, the elements of all these distinct functions, in turn, must be able to do the same at an integrative level to ensure the safe and efficient transport of a bolus from the mouth to the stomach.