Laryngoscopies in the Obese: Predicting Problems and Optimizing Visualization

Objectives:

This pilot study was designed to 1) identify predictors of difficult laryngeal exposure in obese patients, 2) develop strategies for efficient intubation and intraoperative visualization of the glottis, and 3) devise perioperative protocols for difficult laryngoscopies.

Methods:

We undertook a retrospective study over a 1-year period of 14 consecutive patients with a body mass index of more than 30 kg/m2 who underwent elective direct laryngoscopy under general anesthesia. Measurements of height, weight, neck circumference, Mallampati score, and Cormack-Lehane classification of the airway were recorded. Problems encountered during anesthesia induction and emergence were also noted. The laryngologist recorded on a visual analog scale the degree of difficulty encountered in obtaining a binocular stereoscopic view and magnification, illumination, and suspension.

Results:

Anatomic challenges during difficult laryngoscopy included decreased neck extension, redundant folds of tissue in the oropharynx and hypopharynx, and upper airway collapsibility. Overall, there was an association between the incidence of difficult laryngeal exposure and the Cormack-Lehane score (r = .57; p = .03), but the Mallampati score was of limited utility to the laryngologist. Neck size in female patients correlated with the Cormack-Lehane score (p = .02). Neither weight nor body mass index were predictive of a difficult laryngeal exposure. Straight blade laryngoscopes with a distal flange allowed greater depth of insertion and provided the best visualization of the glottis.

Conclusions:

An appropriate clinical examination may help predict a difficult airway. However, further studies are warranted to fully characterize the anatomic predictors of a difficult laryngeal exposure.

Surface electrical stimulation perturbation context determines the presence of error reduction in swallowing hyolaryngeal kinematics

PURPOSE

Error-based learning (EBL) involves gradually reducing movement errors caused by a perturbation. When the perturbation has been unexpectedly removed, exaggerated movements occur in the opposite direction of a perturbation effect, known as aftereffects. Our goal was to determine whether the perturbation type impacts error reduction or aftereffects in swallowing hyolaryngeal kinematics.

METHOD

We perturbed peak hyolaryngeal elevation during swallowing in 16 healthy adults with surface electrical stimulation (SES) in 2 different ways during videofluoroscopy: intermittent SES (I-SES) was applied only during swallowing, and continuous SES (C-SES) was applied during swallowing and during interswallow intervals. In C-SES and I-SES, the onset and offset of the perturbation were unmasked.

RESULTS

Only the C-SES perturbation caused error reduction (gradually increasing peak elevation). Aftereffects were absent in both perturbations, unlike findings from our previous study with masked perturbation. Furthermore, the duration of laryngeal vestibule closure (dLVC) increased during the I-SES perturbation but was unchanged during C-SES perturbation.

CONCLUSION

EBL of swallowing airway protection events was strongly influenced by the context of the perturbation. These findings also elucidate how the relationship among critical swallowing airway protection events (hyoid peak, laryngeal peak, and dLVC) can be modified during EBL.

Anterior cervical osteophyte dysphagia: manofluorographic and functional outcomes after surgery

BACKGROUND

Our aim was to investigate the clinical and manofluorographic findings of patients with anterior cervical osteophyte (ACO) dysphagia before and after surgery.

METHODS

Chart review including manofluorography (MFG) data of patients undergoing ACO removal was undertaken.

RESULTS

Thirteen patients underwent transcervical ACO removal over a 10-year period. A postoperative hematoma was the only surgical complication. Overall, there was a significant postoperative decrease in Functional Outcome Swallowing Scale (FOSS). MFG data showed an elevated preoperative intrabolus pressure gradient across the osteophyte (IB-Gra), 39.78 mm Hg, and IB-Gra significantly decreased to 19 mm Hg 6 months after surgery.

CONCLUSION

Functional (FOSS) and objective MFG (IB-Gra) improvements occurred in patients who had ACO dysphagia and underwent surgery. These findings support high IB-Gra as a reliable objective indicator for surgical intervention for ACO dysphagia and IB-Gra as an appropriate parameter for follow-up after ACO removal. In selected patients, ACO removal by anterolateral-transcervical approach is a safe and highly effective treatment.

[Visualization of laryngopharynx during swallowing of negative contrast media (air) with cine mode 64-row MDCT]

Video fluoroscopic examination of swallowing generally needs a contrast media such as a barium sulfate. Since the examination is usually performed in patients with dysphasia, there is a risk of aspiration. We tried to visualize the laryngopharynx during swallowing of negative contrast media (air) with 64-row multi-detector computed tomography (64-MDCT). Cine mode 64-MDCT was performed to visualize the laryngopharynx in 4 healthy volunteers during swallowing of negative contrast media (air). The data were converted to three-dimensional (3D) images of 2 conditions (air and bone) and sagittal images of the soft tissue condition at a workstation. These images were sent to a personal computer and modeled to 3D cine images with Digital Imaging and Communication in Medicine (DICOM) Viewer and Quick Time Player. 3D cine images demonstrated movements of the epiglottis, vallecula, piriform sinus, tongue, pharyngeal wall, hyoid bone and thyroid cartilage.

Regulation of hypopharyngeal gland activity and oogenesis in honey bee (Apis mellifera) workers

In the honey bee, vitellogenin has several functions in addition to egg provisioning. Among others, it serves as a precursor to brood food proteins secreted by the hypopharyngeal glands of worker bees. In queenless workers with developing gonads, oogenesis and development of the hypopharyngeal glands are correlated. Here we describe two experiments that explored whether this relationship also exists in non-reproductive workers, and investigated a possible role of ecdysteroid hormones in the regulation of vitellogenin uptake. In the first experiment, the correlation between oocyte length and hypopharyngeal gland development was measured in workers before and after de-queening. In the second experiment, we induced middle-aged bees with resting glands to suddenly initiate brood care behaviour, and measured haemolymph ecdysteroid and vitellogenin titres. A strong positive relationship existed between morphometrical parameters of hypopharyngeal glands and ovaries in both queenless and queenright (functionally sterile) workers. No response of ecdysteroid titres to the addition of brood was detected in experiment 2, but high concentrations were measured in a small group of bees characterised by the possession of oocytes on the brink of yolk incorporation. We conclude that hypopharyngeal glands may belong to a previously described group of reproduction-related traits that are pleiotropically regulated in workers. A possible role for ecdysteroids in honey bee reproduction is discussed.

Evaluation of manometric measures during tongue-hold swallows

PURPOSE

Based on visual inspection, prior research documented increased movement of the posterior pharyngeal wall in healthy volunteers during tongue-hold swallows. This manometric study investigated the immediate effects of the tongue-hold maneuver on pharyngeal peak pressure generation, duration of pressure generation, and pressure slope measurements in healthy volunteers.

METHOD

Pharyngeal pressures from 40 young, healthy individuals (mean age = 25.8 years, gender equally distributed) were recorded at 3 locations: oropharynx, hypopharynx, and upper esophageal sphincter (UES), during normal control and tongue-hold swallows. Measures of peak amplitude, duration, and slope of pressure generation were subjected to statistical analysis.

RESULTS

Tongue-hold swallows produced lower pharyngeal peak pressure and shorter pharyngeal pressure durations compared to control swallows. Further, tongue-hold swallows produced lower UES relaxation pressures. Between sensors, peak pressure was lower and pressure slopes were steeper in the hypopharynx compared to the oropharynx. Several gender-specific differences were found for pharyngeal peak pressure, pressure duration, and pressure slopes.

CONCLUSIONS

Reduced amplitude and duration of pharyngeal peak pressure is likely a result of decreased base of tongue retraction during tongue-hold swallows. Central clinical considerations and future research directions are discussed in this article.

Upper airway volume segmentation analysis using cine MRI findings in children with tracheostomy tubes

OBJECTIVE

The purpose of this study is to evaluate the airway dynamics of the upper airway as depicted on cine MRI in children with tracheotomy tubes during two states of airflow through the upper airway.

MATERIALS AND METHODS

Sagittal fast gradient echo cine MR images of the supra-glottic airway were obtained with a 1.5T MRI scanner on seven children with tracheotomy tubes. Two sets of images were obtained with either the tubes capped or uncapped. The findings of the cine MRI were retrospectively reviewed. Volume segmentation of the cine images to compare the airway volume change over time (mean volume, standard deviation, normalized range, and coefficient of variance) was performed for the capped and uncapped tubes in both the nasopharynx and hypopharynx (Signed Rank Test).

RESULTS

Graphical representation of the airway volume over time demonstrates a qualitative increased fluctuation in patients with the tracheotomy tube capped as compared to uncapped in both the nasopharyngeal and hypopharyngeal regions of interest. In the nasopharynx, the mean airway volume (capped 2.72 mL, uncapped 2.09 mL, p = 0.0313), the airway volume standard deviation (capped 0.42 mL, uncapped 0.20 mL, p = 0.0156), and the airway volume range (capped 2.10 mL, uncapped 1.09 mL, p = 0.0156) were significantly larger in the capped group of patients. In the hypopharynx, the airway volume standard deviation (capped 1.54 mL, uncapped 0.67 mL, p = 0.0156), and the airway volume range (capped 6.44 mL, uncapped 2.93 mL, p = 0.0156) were significantly larger in the capped tubes. The coefficient of variance (capped 0.37, uncapped 0.26, p = 0.0469) and the normalized range (capped 1.52, uncapped 1.09, p = 0.0313) were significantly larger in the capped tubes.

CONCLUSION

There is a statistically significant change in airway dynamics in children with tracheotomy tubes when breathing via the airway as compared to breathing via the tracheotomy tube.

Volitional control of food transport and bolus formation during feeding

When healthy individuals eat solid food, chewed food is usually transported to the oropharynx where it accumulates before swallowing (stage II transport). We tested the hypothesis that this transport process can be altered by volition. Eight healthy young subjects ate 8 g pieces of cookie with barium while movements were recorded with videofluorography. There were two trials for each subject, each with different instructions: 1) without command: to eat the cookie in his/her usual manner; 2) with command: to chew the cookie, give a signal when ready to swallow, and then swallow on command of the investigator. We measured the number of chewing cycles, the duration of each stage in the feeding sequence, and the position of the leading edge of the barium at time of command and at swallow onset. Sequence duration was longer with than without command (P=0.02), primarily because of an increase in the number of chewing cycles (P=0.02). The leading edge was typically higher in the foodway at the time of swallow onset with than without command (P=0.06). Under the command condition, stage II transport was delayed, and transport to the valleculae was inhibited. Volition alters swallow initiation in both the timing and location of the food bolus relative to the airway.

The Effects of Breath-Holds and Muller Manoeuvres on Upper Airway Carbon Dioxide Concentration in Humans

<i>Background:</i> Obstructive sleep apnoea is caused by collapse of the upper airway. The presence of CO₂ in the upper airway lumen evokes a number of reflexes which favour upper airway re-opening, and we have proposed previously that CO₂ would build up in the upper airway following airway collapse and that this would contribute to reflex airway re-opening. However, it is not known if CO₂ can transfer from the alveoli to the anatomical dead space of the upper airway during apnoea. <i>Objectives:</i> To determine if alveolar CO₂ can enter the upper airway during breath-holds and Muller manoeuvres. <i>Material and Methods:</i> With local ethics committee approval, 6 male volunteers (aged 22–48 years), following a quiet inspiration, carried out breath-holds and Muller manoeuvres until breaking point. CO₂ was measured continuously in samples obtained from the hypopharynx using an infrared analyser with a sample rate of 50 ml/min. Muller manoeuvres (forced inspirations against a closed upper airway) mimic the respiratory efforts which occur during obstructive apnoeas. <i>Results:</i> In all cases, CO₂ increased progressively during apnoeas. There was a much larger increase in Muller manoeuvres (3.78 ± 0.51%, mean ± SEM at breaking point) compared to breath-holds. <i>Discussion:</i> These results show that upper airway CO₂ concentration rises substantially during apnoeas and suggest that transfer of CO₂ from the lungs to the upper airway may evoke a number of reflex effects which could affect breathing and upper airway re-opening during obstructive apnoeas.

Acoustic roles of the laryngeal cavity in vocal tract resonance

The acoustic effects of the laryngeal cavity on the vocal tract resonance were investigated by using vocal tract area functions for the five Japanese vowels obtained from an adult male speaker. Transfer functions were examined with the laryngeal cavity eliminated from the whole vocal tract, volume velocity distribution patterns were calculated, and susceptance matching analysis was performed between the laryngeal cavity and the vocal tract excluding the laryngeal cavity (vocal tract proper). It was revealed that the laryngeal cavity generates one of the formants of the vocal tract, which is the fourth in the present study. At this formant, the resonance of the laryngeal cavity (the 1/4 wavelength resonance) induces the open-tube resonance of the vocal tract proper (the 3/2 wavelength resonance). At the other formants, on the other hand, the vocal tract proper acts as a closed tube, because the laryngeal cavity has only a small contribution to generating these formants and the effective closed end of the whole vocal tract is the junction between the laryngeal cavity and the vocal tract proper.

[24-hour pH monitoring of the hypopharynx in 545 patients with special regard to a critical data evaluation]

BACKGROUND

Although a number of reports exist on 24-hour pH monitoring of the hypopharynx, no consensus has been reached about evaluation standards. In particular the influence of food and beverages is still different estimated. The parameters which are used to analyze the data of pharyngeal pH monitoring are not consistent.

PATIENTS AND METHODS

545 patients underwent esophagopharyngeal 24-hour pH monitoring in the Department of Otorhinolaryngology at the University of Rostock from February 1996 to December 2003. A score was calculated by excluding technical artefacts and pH drop caused by ingestion.

RESULTS

Pharyngeal acid exposure was detected in 228 patients. The values of the reflux score ranged between 0 - 62,4 with a median value of zero. The left skewed score distribution shows a high abundance of patients with a minimum score and a limited amount of patients with high score values. The results were compared to reports of other authors.

CONCLUSIONS

Evaluation standards are necessary for a reproducible analysis of pharyngeal pH monitoring data and for the comparison of different reports. A qualified score for the analysis and the comparison of pharyngeal pH monitoring data is suggested.

Functional outcomes after free flap reconstruction of the upper aerodigestive tract

PURPOSE OF REVIEW

When the complex structures of the upper aerodigestive tract are disrupted after resection of head and neck tumors, an appropriate reconstructive option should be chosen in an attempt to regain maximum function. Reconstructions using microvascular free tissue transfer offer unparalleled flexibility, both in tissue composition and in placement. This article will examine functional outcomes after free flap reconstruction of the upper aerodigestive tract.

RECENT FINDINGS

With the maturation of free tissue transfer techniques, functional outcomes are being analyzed with increasing frequency. Recent reports show promising results for free flap reconstruction of oral cavity, oropharyngeal, and hypopharyngeal soft tissue defects, as well as for bony mandibular and maxillary defects.

SUMMARY

For both soft tissue and bony defects of the upper aerodigestive tract, microvascular free flaps provide good functional outcomes. In the future, randomized studies are needed to compare the functional outcomes of microvascular free flaps with those of other reconstructive options.

[Laryngopharyngeal structural analysis and its morphofunctional correlation with cricopharyngeal myotomy, botulinum toxin injection and balloon dilation]

BACKGROUND

The cricopharyngeal muscle is of the skeletal type and, in this way, unable to sustain continuous contraction for long periods. Despite of this it has been considered as the responsible by the high pressure area, registered by manometry into the pharyngoesophageal transition. For this reason, it has been the object of therapeutics that promote the rupture of its integrity.

AIMS

To give the anatomical bases to define the limits of participation of the cricopharyngeal muscle in the pharyngoesophageal transition function. To consider a morphological and functional alternative to explain the high pressure area on pharyngoesophageal transition and the implications of the myotomy, use of the botulinum toxin and balloon dilatation on pharyngoesophageal transition function.

MATERIAL AND METHOD

Study of the laryngopharyngeal region in their morphologic characteristics and relationships on 24 pieces obtained from adults' corpses of both sexes fixed in 10% formaldehyde solution.

RESULTS

The cricopharyngeal muscle presenting its anterior-lateral insertion, with a C-shaped outline, on the posterior-lateral edge of the cricoid cartilage. This kind of morphology blocks the possibility to generate a predominant anterior and posterior high pressure during its contraction like that we find at the pharyngoesophageal transition. The observation of this kind of pressure has its explanation in a tweezers-like relationship exerted on one side by the vertebral body and on the other side by the posterior contour of the cricoid cartilage.

CONCLUSIONS

The muscular organization of the laryngopharyngeal segment allowed us to sustain that a large myotomy of the pharyngoesophageal transition, that takes more than just the cricopharyngeal transversal fasciculus, hinders the ejection function in a region where the dimension do not need any parietal sectioning. Myotomy that encompasses only the transversal fasciculus can contribute to improve the pharyngoesophageal flux by a decrease of the local resistance. The efficiency of this myotomy depends mostly on some residual pharyngeal ejection force and also on a slight hyolaryngeal displacement. The transversal fasciculus of the cricopharyngeal muscle is a narrow strip of muscular mass to be injected by percutaneous way with solution of botulinum toxin; maybe endoscopically. For this reason, dose, dilution and injection sites have an important meaning in the cricopharyngeal therapeutics using botulinum toxin. The efficiency of this procedure, like myotomy, depends on some residual pharyngeal ejection force and on, at least, some hyolaryngeal displacement. The dilation of the pharyngoesophageal transition with pneumatic balloon does not seem to be an adequate procedure for a region that does not present a narrow lumen determined by fibrosis. For anatomical characteristics of the TFE region, mean pressure as registered by the manometric method does not evaluate either the effectiveness or inadequacy of surgical myotomy, denervation or dilation using pneumatic balloon.

Cough, expiration and aspiration reflexes following kainic acid lesions to the pontine respiratory group in anesthetized cats

The importance of neurons in the pontine respiratory group for the generation of cough, expiration, and aspiration reflexes was studied on non-decerebrate spontaneously breathing cats under pentobarbitone anesthesia. The dysfunction of neurons in the pontine respiratory group produced by bilateral microinjection of kainic acid (neurotoxin) regularly abolished the cough reflexes evoked by mechanical stimulation of both the tracheobronchial and the laryngopharyngeal mucous membranes and the expiration reflex mechanically induced from the glottis. The aspiration reflex elicited by similar stimulation of the nasopharyngeal region persisted in 73% of tests, however, with a reduced intensity compared to the pre-lesion conditions. The pontine respiratory group seems to be an important source of the facilitatory inputs to the brainstem circuitries that mediate cough, expiration, and aspiration reflexes. Our results indicate the significant role of pons in the multilevel organization of brainstem networks in central integration of the aforementioned reflexes.

Sequence variability during hypopharyngeal bolus transit

The pharyngeal phase of deglutition is considered to occur in a reflexive, preprogrammed fashion. Previous studies have determined a general sequence of events based on the mean timing of bolus transit and swallowing gestures. Individual variability has not been studied, however. The purpose of this study was to determine the amount of sequence variability that normally occurs during the hypopharyngeal phase of deglutition. Dynamic swallow studies from 60 normal volunteers were evaluated and event sequence variability was determined for 12 two-event sequences during swallowing of three bolus sizes. There was found to be some variability in event sequences for almost all events evaluated except for the following: (1) arytenoid cartilage elevation always began prior to opening of the upper esophageal sphincter, (2) the sphincter always opened prior to the arrival of the bolus at the sphincter, (3) larynx-to-hyoid approximation always occurred after the onset of upper esophageal sphincter opening, and (4) maximum pharyngeal constriction always occurred after maximal distension of the upper esophageal sphincter. Variability was more common during swallowing of the smallest bolus size. This information may be helpful in evaluating event coordination in patients with dysphagia.

[Morphology and function of the pharyngoesophageal segment]

Basing on the review of the foreign and domestic literature the point of view concerning the anatomical structure, innervation and histomorphology of the pharyngoesophageal segment (pes) is being presented. Special attention was paid to the impact of the somatic and autonomic (particularly its sympathetic part) nervous system on the function of the pharynx, as well as the pressure at rest with the pharyngoesophageal sphincter. Histomorphologic investigations suggest that the pes function and tension of the particular pharyngeal constrictors (upper, middle and inferior) is determined by: a) structure, b) distribution of the IX and X nerve fibre ends in pharyngeal sphincters, c) structure of the pharyngeal sphincter, which is also supplied with the nervous fibre ends of the upper cervical sympathetic trunk. The sympathetic trunk is located on both sides of vertebral column from the skull base till the tip of the sacral bone. In case of degenerative process in the neck segment of the vertebral column, irritation of the sympathetic part of the autonomic system is taking place. Experimental investigations revealed that the stimulation of the sympathetic nervous fibres of the autonomic system results in weakening of the upper and middle pharyngeal sphincter's tension and increase of tension in its lower part (cricopharyngeal muscle). This can be an etiopathogenic factor under physiological condition in disturbances of the pharyngeal phase of deglutition act. After total laryngectomy, however, high pressure in the lower part of the pes (in the area of pharyngoesophageal sphincter) renders it difficult or even impossible to introduce the air into the esophagus to master the phonation and esophageal speech. The significance of the knowledge of the pes innervation in clinical practice is important for prognosis in mastering of supplementary, esophageal and shunt phonation.

Mechanical properties of the passive pharynx in Vietnamese pot-bellied pigs. II. Dynamics

We described the dynamic mechanical properties of the passive pharynx in Vietnamese pot-bellied pigs and the effects of caudal tracheal displacement. During general anesthesia and neuromuscular blockade, airflow through the upper airway (V) and pharyngeal cross-sectional area were measured during ramp decreases in pressure downstream from the pharynx (Pdown). Measurements were made with 0, 1, and 2 cm of caudal tracheal displacement. Airflow limitation and/or negative pressure dependence (NPD) were observed in all animals. Tracheal displacement (2 cm) increased maximal V (V(max)) by 205.1 +/- 105.1% (P < 0.05) relative to the value with no displacement and increased the magnitude of NPD, expressed as percent decrease in V from V(max), from 22.9 +/- 27.4 to 56.6 +/- 37.5% (P < 0.05). Initial decreases in Pdown narrowed all levels of the pharynx, but, once V(max) was reached, further decreases in Pdown narrowed the hypopharynx but not the nasopharynx and oropharynx. We conclude that the hypopharynx is the flow-limiting site in the pig pharynx. Tracheal displacement not only improved airflow dynamics as V(max) increased but also resulted in pronounced NPD.

Mechanical properties of the passive pharynx in Vietnamese pot-bellied pigs. I. Statics

The static mechanical properties of the passive pharynx were investigated in Vietnamese pot-bellied pigs by using an isolated upper airway preparation. During general anesthesia and neuromuscular blockade, cross-sectional area (A) of the pharynx was measured while airway pressure (Paw) was held at various pressures in the absence of airflow. The static A-Paw relationship was measured during application of 0, 1, and 2 cm of caudal tracheal displacement. Relative to humans, closing pressures (Pclose) of the pig pharynx were very low (-15 to -35 cmH(2)O). Tracheal displacement significantly decreased compliance of the hypopharynx (from 0.074 +/- 0.02 cm(2)/cmH(2)O with no displacement to 0.052 +/- 0.01 cm(2)/cmH(2)O with 2 cm of displacement) and decreased Pclose of the oropharynx (from -18.2 +/- 9.9 cmH(2)O to -24.1 +/- 10.5 and -28.7 +/- 12.3 cmH(2)O with 1 and 2 cm of displacement, respectively). Tracheal displacement did not affect A of the pharyngeal segments. In conclusion, tracheal displacement decreased collapsibility of the passive pharynx. The pharynx of the pot-bellied pig is structurally more resistant to collapse than the human pharynx.

The effect of neuromuscular stimulation of the genioglossus on the hypopharyngeal airway

OBJECTIVES

To determine the effects of neuromuscular stimulation (NS) of the genioglossus muscle on hypopharyngeal airway size.

STUDY DESIGN

Fourteen consecutively recruited healthy volunteers underwent percutaneous electrical NS of the genioglossus muscle.

METHODS

Bipolar hooked wires were inserted percutaneously into the genioglossus muscle and used for NS. The anterior--posterior diameter of the hypopharynx was measured at the level of the superior edge of the epiglottis at baseline and during NS from recorded video endoscopic examinations.

RESULTS

NS of the genioglossus muscle resulted in a significant increase in the diameter of the hypopharyngeal airway (P =.002) compared with baseline, ranging from a 33% to 284% increase in airway diameter. Three of the 14 patients demonstrated modest decreases in airway diameter, likely the result of faulty electrode placement in surrounding tongue retrusive muscles.

CONCLUSIONS

NS of the genioglossus muscle was effective in increasing the hypopharyngeal airway and may provide a useful alternative to direct stimulation of the hypoglossal nerve with a nerve cuff electrode in the development of neuroprosthetic treatments for obstructive sleep apnea.

Sublingual electrical stimulation of the tongue during wakefulness and sleep

Pharyngeal obstruction in patients with obstructive sleep apnea (OSA) is thought to result from decreased upper airway muscle tone during sleep. The goal of the present study was to estimate the role of the tongue muscles in maintaining pharyngeal patency during sleep. Using non-invasive, sub-lingual surface electrical stimulation (ES), we measured tongue protrusion force during wakefulness and upper airway resistance during sleep in seven healthy subjects and six patients with OSA. During wakefulness, ES produced similar protrusion forces in healthy subjects and patients with OSA. ES of the anterior sublingual surface, causing preferential contraction of the genioglossus, resulted in smaller effects than combined ES of the anterior and lateral surface, which also stimulated tongue retractors. During sleep, trans-pharyngeal resistance decreased and peak inspiratory flow rate increased from 319+/-24 to 459+/-27 and from 58+/-16 to 270+/-35 ml/sec for healthy subjects and OSA patients, respectively (P<0.001). However, ES was usually unsuccessful in reopening the upper airway in the presence of complete apneas. We conclude that non-invasive ES of the tongue improves flow dynamics during sleep. Combined activation of tongue protrusors and retractors may have a beneficial mechanical effect. The magnitude of responses observed suggests that in addition to the stimulated muscles, other muscles and/or forces have a substantial impact on pharyngeal patency.

Upper airway pressures in snorers and nonsnorers during wakefulness and sleep

OBJECTIVE

To compare upper airway pressures in snorers and nonsnorers during sleep and wakefulness.

DESIGN

Case series of snorers and nonsnoring controls.

SETTING

Sleep clinic of a university hospital.

METHODS

We used open catheters to measure differential nasopharyngeal and hypopharyngeal pressures in 8 nonapneic snorers with excessive daytime tiredness and 10 healthy nonsnoring controls. Measurements were performed during sleep (with the mouth taped to ensure exclusively nasal breathing) and wakefulness. When awake, the subjects were either seated (with the head neutral, flexed, extended, or rotated) or recumbent (dorsal and lateral positions).

MAIN OUTCOME MEASURES

Comparison of pressures within the group as a function of body position and between the groups as a function of snoring.

RESULTS

Differential nasal and pharyngeal pressures were similar in seated snorers and nonsnorers independently of head position. Assumption of recumbency resulted in significantly increased pharyngeal pressures in nonsnorers (26 +/- 18 Pa seated vs. 52 +/- 46 Pa recumbent, p < .05) and snorers (50 +/- 35 Pa seated vs. 93 +/- 38 recumbent, p < .01). The increase was higher in snorers than nonsnorers. During snoring, sleep differential pharyngeal pressures in snorers were markedly increased compared to quiet sleep (567 +/- 450 Pa during snoring epochs vs. 117 +/- 82 Pa during nonsnoring epochs, p < .01).

CONCLUSIONS

Compared to nonsnorers, recumbent nonapneic snorers have elevated differential pharyngeal pressures indicative of increased upper airway resistance and reduced airway patency; this is present during wakefulness and sleep.

Motor strategy in rapid sequential swallowing: new insights

This study examined the physiological properties and movement strategies of normal, rapid sequential swallowing during simultaneous videofluoroscopy (VFS) and submental surface electromyography (EMG). Ten subjects performed discrete (5 and 15 cc) and sequential (150 cc in tilted and upright head postures) swallowing tasks. Analyses included VFS event timing, movement/bolus passage characteristics, EMG amplitude waveforms, and peak and offset EMG amplitudes. Results revealed that sequential swallows were significantly shorter than discrete swallows in several VFS event durations, but significantly longer in pharyngeal transit and stage transition times. The hyolaryngeal system exhibited a cyclical "rise and partial fall" movement pattern during sequential swallows on VFS, corresponding to a repetitive "activation and partial deactivation" characteristic on EMG. Greater peak EMG amplitude for sequential than discrete swallows was found in 6/10 subjects. Pharyngeal bolus merging, preparatory laryngeal gestures, and penetration without aspiration were also observed in some subjects on VFS. Intersubject differences were significant in timing measures and EMG amplitude. Our findings of individual variability and subject-specific strategies for task accommodation support the notion of built-in plasticity in the deglutitive motor complex.

The effect of mechanoreceptor stimulation of the laryngopharynx on the oesophago-gastric junction

Stimulation of the pharynx by injection of minute amounts of water induces prolonged period of lower oesophageal sphincter (LOS) relaxation and augmentation of the crural diaphragm (CD) contraction. The purpose of this study was to determine the effects of stimulating mechano-receptors at the laryngopharynx on the LOS and CD by using an air pulse stimulation device. Air pulses were delivered via the internal channel of a flexible endoscope. Oesophageal, LOS, and CD pressures; CD electromyogram; and oesophageal pH 5 cm above the LOS were recorded in nine healthy subjects. Stimulation of the laryngopharynx induced LOS relaxation in the absence of swallow and oesophageal peristalsis. The stimulation of epiglottis and arytenoid produced higher incidence of LOS relaxation compared to the base of tongue. The magnitude of LOS relaxation differed significantly between the three anatomical sites, with greater relaxation occurring at the epiglottis and arytenoid compared with the base of the tongue. None of the LOS relaxations induced by laryngeal stimulation resulted in inhibition of the CD or gastroesophageal reflux. We conclude that stimulation of the laryngopharyngeal mechanoreceptors induces LOS but not CD relaxation. The LOS relaxation induced by laryngopharyngeal stimulation is not accompanied by acid reflux in fasting state.

Timing of events in normal swallowing: a videofluoroscopic study

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for clinically useful timing measures. The relation of swallowing gesture timing to the timing of actual bolus transit was of particular interest because it provides insight into the physiology of larger bolus volume accommodation. Parameters evaluated include the timing of bolus pharyngeal transit, soft palate elevation, aryepiglottic fold elevation and supraglottic closure, arrival of the bolus in the vallecula, hyoid bone displacement onset and duration, arrival of the bolus at the pharyngoesophageal sphincter, maximum pharyngeal constriction, and pharyngoesophageal sphincter opening. These parameters represent events required for normal deglutition, can be used to identify abnormalities in dysphagic patients, and provide a basis for comparison of swallowing performance both within and between patients. In addition, our experience has shown them to be reliably obtained. Other investigators have reported some of the measurements. However, to our knowledge, normative data for timing of aryepiglottic fold elevation, soft palate elevation and closure, and maximum pharyngeal constriction have not been described. Other measures included in the present study may provide alternatives when conventional measures cannot be obtained in selected patients. The relevance and clinical utility of new and alternative measures, in particular, are discussed.

Respiratory and acoustic signals associated with bolus passage during swallowing

In order to advance our understanding of the relation between respiration and deglutition, simultaneous videofluoroscopy and respirodeglutometry was performed. Fifteen normal, healthy, young adults (20-29 years of age) were connected to a respirodeglutometer and positioned for simultaneous videofluoroscopic assessment in the lateral plane. Subjects performed three swallows each of a 5-ml and a 10-ml bolus of liquid barium and a 5-ml bolus of paste barium, for a total of nine swallows per subject. Location of the bolus head as identified with videofluoroscopy was associated with eight respirodeglutometric variables. In addition, temporal relations for seven respirodeglutometric variables were calculated as a function of bolus volume and viscosity. Significant temporal differences were found for five of the variables by volume. No significant temporal differences were noted by viscosity. Expiration occurred before 79% and after 96% of the swallows. The number of inspirations preceding a swallow suggested a possible effect resulting from the need to hold a bolus in the mouth before receiving instructions to swallow during videofluoroscopic assessment. This effect may be important during patient evaluation. For a significant number of swallows, respiratory flow ceased before the velum was fully elevated.

Sensory nerve supply of the human oro- and laryngopharynx: a preliminary study

To date, the details of human sensory innervation to the pharynx and upper airway have not been demonstrated. In this study, a single human oro- and laryngopharynx obtained from autopsy was processed with a whole-mount nerve staining technique, Sihler's stain, to determine its entire sensory nerve supply. The Sihler's stain rendered all mucosa and soft tissue translucent while counterstaining nerves. The stained specimen was then dissected and the nerves were traced from their origins to the terminal branches. It was found that the sensory innervation of the human pharynx is organized into discrete primary branches that innervate specific areas, although these areas are often connected by small neural anastomoses. The density of innervation varied, with some areas receiving almost no identifiable nerve supply (e.g., posterior wall of the hypopharynx) and certain areas contained much higher density of sensory nerves: the posterior tonsillar pillars; the laryngeal surface of the epiglottis; and the postcricoid and arytenoid regions. The posterior tonsillar pillar was innervated by a dense plexus formed by the pharyngeal branches of the IX and X nerves. The epiglottis was densely innervated by the internal superior laryngeal nerve (ISLN) and IX nerve. Finally, the arytenoid and postcricoid regions were innervated by the ISLN. The postcricoid region had higher density of innervation than the arytenoid area. The use of the Sihler's stain allowed the entire sensory nerve supply of the pharyngeal areas in a human to be demonstrated for the first time. The areas of dense sensory innervation are the same areas that are known to be the most sensitive for triggering reflex swallowing or glottic protection. The data would be useful for further understanding swallowing reflex and guiding sensory reinnervation of the pharynx to treat neurogenic dysphagia and aspiration disorders.

Diagnosis of lateral hypopharyngeal pouches: a comparative study of videofluorography and pseudovalsalva maneuver in double contrast pharyngography

BACKGROUND

To evaluate the difference between the pseudovalsalva maneuver in double-contrast pharyngography and the videofluorographic swallowing examination in the detection and grading of lateral hypopharyngeal pouches.

METHODS

Two hundred twenty-seven videofluorographic swallowing examinations and double-contrast pharyngography using the pseudovalsalva maneuver were retrospectively analyzed by two radiologists. The mean age of the patients was 54 years (range = 21-81 years). The examination was performed on a fluoroscopy unit with a U-matic videorecording system in standard projections. Iodinated contrast agent was used, followed by barium if there was no massive aspiration.

RESULTS

In contrast to the videofluorographic swallowing examination, which showed 170 lateral hypopharyngeal pouches (113 grade I, 39 grade II, 18 grade III) in 101 patients, the pseudovalsalva maneuver showed 304 pouches (304 grade III) in 179 patients. No videofluorographically diagnosed lateral hypopharyngeal pouches were missed by the pseudovalsalva maneuver; 134 pouches in 78 patients diagnosed with pseudovalsalva maneuver had no correlation videofluorographically.

CONCLUSION

Double-contrast pharyngography using the pseudovalsalva maneuver is not a reliable method for the diagnosis of lateral hypopharyngeal pouches.

Role of laryngeal movement and effect of aging on swallowing pressure in the pharynx and upper esophageal sphincter

OBJECTIVES

Describe contribution of laryngeal movement to pressure changes at the upper esophageal sphincter (UES) and the effect of aging on the swallowing function.

STUDY DESIGN

Manofluorography on 56 nondysphagic adults divided into three age groups: the 21- to 31-year-old group (n = 32), the 61- to 74-year-old group (n = 12) and the 75- to 89-year-old group (n = 12). Analyses of the bolus transit time, the amplitudes and durations of pharyngeal pressures, the timing of a pressure fall at the UES and the laryngeal movements.

METHODS

Intraluminal strain-gauge sensors recorded pressure changes in the oropharynx, hypopharynx and the UES. Motion pictures of the videotapes were fed into a personal computer, and movements of the hyoid bone were measured in both the horizontal and vertical directions as an indication of laryngeal movement.

RESULTS

In 26- and 70-year-old men with calcification of the thyroid cartilage, it was determined that the larynx and hyoid bone moved in consonance until the end of the rapid hyoid movements in both the superior and anterior directions. In the 21- to 31-year-old group, the magnitude of the pressure fall at the UES was maximal before or almost at the same time as the bolus arrival, in preparation for smooth passage of the bolus from the pharynx to the esophagus. The rapid superior movements of the hyoid bone started significantly early as compared with its anterior movements (P = .0001). The rapid anterior movements of the hyoid bone started simultaneously with the pressure fall at the UES. In the elderly, all segmental transit times were significantly increased. The timing of the pressure fall at the UES was significantly delayed and the UES pressure reached its minimum value after arrival of the bolus at the UES. The minimum pressure at the UES increased to a significantly positive value. The rapid anterior movements of the hyoid were significantly delayed, suggesting that this delay causes the delay in the pressure fall at the UES.

CONCLUSIONS

The rapid superior and anterior movements of the hyoid bone are considered to start at the same time as those of the larynx. In the young group, it is suggested that superior laryngeal movement protects the lower airway prior to the anterior laryngeal movement, causing the pressure fall at the UES to enable the passage of a bolus into the UES. In the elderly, smooth passage of the bolus from the pharynx to the esophagus is hindered and the system that prevents aspiration is rendered inefficient by changes in the swallowing pressures and laryngeal movements with aging.

Diagnosing respiratory events and tracing air flow by internal thermistors

We have developed a new method to measure flow in patients with sleep-related breathing disorders (SRBD). These flow sensors are modified thermistors located in the same sensors we use for pressure measurement in the upper airways to find the obstructive segments during apnoeas. The aim of this study was to test if using internal thermistors as indicator of air flow has advantages compared with the external thermistor method in detecting respiratory events. A total of 50 consecutive patients with an apnoea-hypopnoea index (AHI) of more than 15 were studied. A standard nocturnal polysomnography (PSG) with both internal and external thermistors was performed in all patients. To estimate the patients' AHI, a detailed analysis viewing all parameters except external and internal thermistors was performed. This was followed by an analysis viewing only internal thermistors signals indicating airflow in the pharynx, and finally an analysis viewing only external thermistor signals indicating air flow at the mouth and nose. Mean AHI measured by the three methods showed 49.8 (SD 23.4) by the PSG, 47.8 (SD 24.9) by internal thermistors alone, and 31.5 (SD 22.2) by external thermistors. There was no statistical difference between AHI detected by PSG and internal thermistors, but highly significant differences between PSG and external thermistors (p < 0.001). The external thermistors missed an average of almost 20 respiratory events per hour.

Reciprocal activation of hypopharyngeal muscles and their effect on upper airway area

We examined in awake goats, 1) with intact upper airways (UAW), the effect of altering chemical drive on pharyngeal constrictors [thyropharyngeus (TP) and hypopharyngeus (HP)] and a dilator [stylopharyngeus (SP)], and 2) with an isolated UAW, the effect of activation of these muscles on supraglottic UAW (UAW(SG)) area. During eupnea in nine goats with intact UAW, the TP and HP were active during expiration, whereas the SP exhibited tonic expiratory and phasic inspiratory activity. After mechanically induced apneas (MIA), TP activity increased (263%, P < 0.02), HP activity exhibited a small, varied response, and SP activity greatly decreased (10%, P < 0.02). During resumption of respiratory effort, all goats exhibited absent/reduced airflow, and when diaphragm activity was 95% of control, TP activity remained elevated (135%) and SP activity was reduced (56%, P < 0.02). During hypercapnia, 1) TP activity decreased (P < 0.02), 2) HP response varied, and 3) SP activity increased (P < 0.02). After MIA in six goats with isolated UAW, TP activity increased 198% (P < 0.02) and UAW(SG) area (endoscopically determined) decreased (to 15% of control, P < 0.02). During recovery from MIA, a correlation was found between UAW(SG) area and the ratio of SP to TP activity. We conclude that the reciprocal activation of mechanically opposing dilator and constrictor muscles in the hypopharynx is correlated to changes in the UAW(SG) area, and an imbalance in activity of these opposing muscles can lead to UAW(SG) narrowing.

Comparison of upper esophageal sphincter opening in healthy asymptomatic young and elderly volunteers

Deglutitive upper esophageal sphincter opening (UES) in the elderly has been incompletely studied. Our aim was to determine in the elderly the temporal and dimensional characteristics of deglutitive UES opening; anterior and superior hyoid and laryngeal excursions as measures of distracting forces imparted on the UES; and hypopharyngeal intrabolus pressure (IBP). Fourteen healthy elderly and 14 healthy young volunteers were studied by concurrent videofluoroscopy and hypopharyngeal manometry during swallowing of 5- and 10-mL barium boluses. The anteroposterior UES diameter, as well as the anterior hyoid bone and laryngeal excursion, was significantly smaller in the elderly compared to the young (p < .05) for 5-mL barium boluses, but not for 10-mL boluses. The lateral diameter of UES opening was similar between groups for all boluses. The IBP for 5- and 10-mL swallows in the elderly was significantly higher than that in the young (p < .05). We conclude that anteroposterior deglutitive UES opening and hyoid bone and thyroid cartilage anterior excursion are reduced in the elderly. These changes are associated with increased IBP, suggesting a higher pharyngeal outflow resistance in the elderly compared to the young.

Laryngopharyngeal sensory discrimination testing and the laryngeal adductor reflex

Laryngopharyngeal sensory capacity has been determined by endoscopically administering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve and asking the patient if he or she feels the stimulus. A potential shortcoming of this psychophysical testing (PT) procedure is that it is a subjective test, and patients with impaired cognition may not be able to perform the required task. In the search for an objective measure of laryngeal sensory function, we have observed that the laryngeal adductor reflex (LAR) is evoked at stimulus intensities similar to those capable of eliciting the psychophysical, or perceptual, response. The purpose of this study is to determine if the threshold for eliciting the LAR is the same as that of the sensory threshold. A specially designed endoscope was used to present air pulse stimuli (range 0.0 to 10 mm Hg) to the laryngopharynx in 20 healthy subjects and in 80 patients with dysphagia, using both PT and the LAR. The patients had a variety of underlying diagnoses, with stroke and chronic neurologic disease predominating (n = 65). In the control group and in the group of patients with dysphagia, there was no statistically significant difference between the median laryngopharyngeal sensory thresholds whether we used PT or the LAR (p>.05, Wilcoxon signed-rank test). The intraclass correlation for the total sample was .999 (U = .999, L = .998). Since psychophysical and sensorimotor reflex thresholds were not statistically significantly different and the intraclass correlation was close to a perfect correlation, we conclude that the LAR can be used as an objective and accurate clinical method of endoscopically assessing laryngopharyngeal sensory capacity.

Preliminary study on the ability of trained singers to control the intrinsic and extrinsic laryngeal musculature

Little literature is available on professional musical theater female singers, a population that regularly uses a wide variety of vocal qualities. This study tested the hypothesis that different vocal qualities cause observable specific configurations of muscular movements and structural changes of the larynx, hypopharynx, oral pharynx, and oral cavity for individual singers. Fiberoptic rigid and flexible endoscopic observation were used to determine visual analysis of such configurations. This study documents observable physiologic changes that were made by professional musical theater female singers in specific vocal qualities.

Comparison of the flexible and standard laryngeal mask airways

PURPOSE

To determine mucosal pressures, ease of insertion, mask position and oropharyngeal leak pressures for the flexible (FLMA) and standard laryngeal mask airway (LMA).

METHODS

Forty anesthetized, paralysed adult patients were randomly allocated to receive either the FLMA or LMA. Microchip sensors were attached to the LMA or FLMA at identical locations corresponding to the base of tongue, hypopharynx, lateral pharynx, oropharynx, posterior pharynx and pyriform fossa. Mucosal pressure, oropharyngeal leak pressure (OLP) and mask position (assessed fibreoptically) were recorded during inflation of the cuff from 0-40 ml in 10 ml increments.

RESULTS

Ease of insertion and mask position were similar between devices. Mean OLP was higher for the LMA (22 vs 19 cm H2O), but the maximum OLP was similar (25 vs 24 cm H2O). Mean mucosal pressures were generally low (< 12 cm H2O) for both devices, but were higher for the LMA in the lateral pharynx (4 vs 1 cm H2O) and oropharynx (13 vs 3 cm H2O) and higher in the posterior pharynx for the FLMA (4 vs 2 cm H2O). The OLP for both devices increased with increasing intracuff volume from 0-10 ml and 10-20 ml, and from 20-30 ml for the FLMA.

CONCLUSIONS

We conclude that the LMA and FLMA perform similarly in terms of ease of insertion and mask position, but OLP and mucosal pressures are slightly higher for the LMA. Pharyngeal mucosal pressures for both devices are lower than those considered safe for the tracheal mucosa. The overall clinical performance between the two devices is similar.

MRI study of regional variations of pharyngeal wall compliance in cats

Upper airway compliance indicates the potential of the airway to collapse and is relevant to the pathogenesis of obstructive sleep apnea. We hypothesized that compliance would vary over the rostral-to-caudal extent of the pharyngeal airway. In a paralyzed isolated upper airway preparation in cats, we controlled static upper airway pressure during magnetic resonance imaging (MRI, 0.391-mm resolution). We measured cross-sectional area and anteroposterior and lateral dimensions from three-dimensional reconstructed MRIs in axial slices orthogonal to the airway centerline. High-retropalatal (HRP), midretropalatal (MRP), and hypopharyngeal (HYP) regions were defined. Regional compliance was significantly increased from rostral to caudal regions as follows: HRP < MRP < HYP (P < 0.0001), and compliance differences among regions were directly related to collapsibility. Thus our findings in the isolated upper airway of the cat support the hypothesis that regional differences in pharyngeal compliance exist and suggest that baseline regional variations in compliance and collapsibility may be an important factor in the pathogenesis and treatment of obstructive sleep apnea.

Long-term facilitation of ventilation in humans during NREM sleep

The purpose of this study was to determine whether episodic hypoxic exposure would elicit long term facilitation (LTF) of ventilation (V(I)) in sleeping humans. Twenty subjects gave written informed consent. Of these, six subjects were unable to maintain stable stage 2 sleep or deeper for a majority of the experiment and their data were excluded from the analysis. On night 1 after subjects had reached stable sleep (stage 2 or deeper), the subjects breathed room air for 5 minutes, followed by 3 minutes of hypoxia (F(I)O2 = 8%). This sequence was repeated 10 times, and the breathing pattern was observed for a further 60 minutes. Subjects returned to the laboratory for a second visit, which served as a sham night. Instrumentation and study time were the same as on night 1, but subjects breathed room air only. Airflow, tidal volume (V(T)), end tidal O2 and CO2, and estimation of arterial O2 saturation (%) were measured. Seven of the subjects had long-term facilitation (LTF), which was manifested as a significant increase in V(I) that persisted for up to 40 minutes following the last hypoxic exposure. In the other seven subjects, no substantial increase in V(I) was found. We could not explain this difference based on body size (BMI), gender, level of hypoxemia, or magnitude of the hyperpnea during hypoxia. The difference between the two groups was that the LTF group consisted of habitual snorers, and that the NLTF were not inspiratory-flow-limited during the experiment.

Proposed catheter standards for pharyngeal manofluorography (videomanometry)

With the recent introduction of commercially available pharyngeal manofluorography systems, catheter design should be standardized. Catheters of different designs can produce different data because of their design characteristics. A standard catheter design should make results between investigators comparable and facilitate acceptable normal values. The authors' combined laboratory experience with many catheter designs was reviewed and the literature consulted. For pharyngeal manofluorography, the proposed standard catheter should be 2 x 4 mm in diameter, ovoid, and 100 cm long. The catheter should be marked in centimeters with an anterior and posterior orientation. There should be a slightly malleable, 3- to 4-cm length without sensors beyond the most distal sensor. Solid state transducer sensors should be three or four in number and placed in the pharyngoesophageal segment, midhypopharynx, and tongue base (esophagus for fourth sensor). Sensor spacing should be 3 cm, except 2 cm between the midhypopharynx and tongue base. Unidirectional, in-line, posteriorly oriented sensors with the option of a single circumferential sensor in the cricopharyngeus are currently preferred over circumferential sensors because of their small diameter (patient comfort).

Influence of altered tongue contour and position on deglutitive pharyngeal and UES function

The potential influence of altered lingual position and contour during the bolus loading phase of the swallow in mediating the swallowed bolus volume-dependent regulation of upper esophageal sphincter (UES) relaxation and opening was studied in 15 healthy volunteers using simultaneous videoradiography and manometry. A maxillary dental splint modulated tongue deformity during the early oral phase of deglutition. We examined the effect of the splint and swallowed bolus density on bolus volume-dependent changes in the timing of events in the swallow sequence and on hypopharyngeal intrabolus and midpharyngeal pressures. Peak mid-pharyngeal pressure (P = 0.001) and hypopharyngeal intrabolus pressure (P = 0.04) were significantly reduced by the splint. The normal volume-dependent earlier onset of sphincter relaxation and opening was preserved with the splint in situ. The splint significantly delayed the onset of hyoid motion and UES relaxation and opening without influencing transit times or total swallow duration. Alterations in tongue contour and position reduce intrabolus pressure and pharyngeal contraction without influencing normal bolus volume-dependent regulation of timing of UES relaxation and opening.

Augmentation of deglutitive upper esophageal sphincter opening in the elderly by exercise

Earlier studies have shown that the cross-sectional area of the deglutitive upper esophageal sphincter (UES) opening in healthy asymptomatic elderly individuals is reduced compared with healthy young volunteers. The aim of this study was to determine the effect of a head-raising exercise on swallow-induced UES opening and hypopharyngeal intrabolus pressure in the elderly. We studied a total of 31 asymptomatic healthy elderly subjects by videofluoroscopy and manometry before and after real (19 subjects) and sham (12 subjects) exercises. A significant increase was found in the magnitude of the anterior excursion of the larynx, the maximum anteroposterior diameter, and the cross-sectional area of the UES opening after the real exercise (P < 0.05). These changes were associated with a significant decrease in the hypopharyngeal intrabolus pressure studied in 12 (real-exercise) and 6 (sham-exercise) subjects (P < 0.05). A similar effect was not found in the sham-exercise group. In normal elderly subjects, deglutitive UES opening is amenable to augmentation by exercise aimed at strengthening the UES opening muscles. This augmentation is accompanied by a significant decrease in hypopharyngeal intrabolus pressure, indicating a decrease in pharyngeal outflow resistance. This approach may be helpful in some patients with dysphagia due to disorders of deglutitive UES opening.

Function of upper esophageal sphincter during swallowing: the grabbing effect

This study investigated deglutitive axial force developed within the pharynx, upper esophageal sphincter (UES), and cervical esophagus. Position and deglutitive excursion of the UES were determined using combined manometry and videofluoroscopy in eight healthy volunteers. Deglutitive clearing force was quantified with a force transducer to which nylon balls of 6- or 8-mm diameter were tethered and positioned within the oropharynx, hypopharynx, UES, and cervical esophagus. Axial force recordings were synchronized with videofluoroscopic imaging. Clearing force was dependent on both sphere diameter (P < 0.05) and location, with greater force exhibited in the hypopharynx and UES compared with the oropharynx and esophagus (P < 0.05). Within the UES, the onset of traction force coincided with passage of the pharyngeal clearing wave but persisted well beyond this. On videofluoroscopy, the persistent force was associated with the aboral motion of the ball caught within the UES. Force abated with gradual slippage of the UES around the ball. The force attributable to the combination of UES contraction and laryngeal descent was named the grabbing effect. The grabbing effect functions to transfer luminal contents distal to the laryngeal inlet at the end of the pharyngeal swallow, presumably acting to prevent regurgitation and/or aspiration of swallowed material.

Mucociliary clearance of stented laryngotracheal tract in guinea pigs in vivo

The purpose of this study was to investigate laryngotracheal mucociliary transport by means of an in vivo guinea pig model with and without a stent. The experimental design involved marking with deep-colored resin powder and utilizing the serial photograph-analyzing method via endoscopic laryngeal videography. Fifteen animals were grouped into two airway conditions: 5 with laryngotracheal stent insertion and 10 without. The mucociliary transit time and mucociliary transport rate were measured in both groups. Significant differences between the two groups were found. In conclusion, stenting preserved and increased the clearance function of the laryngotracheal mucosa in the acute phase.

Upper airway size and collapsibility in snorers: evaluation with digital fluoroscopy

This study addressed the question of whether there are any differences in the size and collapsibility of the upper airway measured by digital fluoroscopy, between snorers and controls whilst they were awake and breathing normally; and whether there are any correlations between these measurements and other clinical data. The dynamic changes of the upper airway size were evaluated using digital fluoroscopy in 33 patients and 16 normal controls. The measurements were compared with findings in an overnight sleep study, including a static-charge-sensitive bed (SCSB) and oximeter recordings. The minimum anteroposterior dimension at the velopharyngeal level was smaller in patients with partial upper airway obstruction than in controls (p<0.005); patients with complete obstruction did not differ from the controls. The velopharyngeal airways were also more collapsible in patients with severe partial obstruction (p<0.01) than in controls. At the oropharyngeal and hypopharyngeal levels, the dimensions and the collapsibilities were similar in patients and controls. The velopharyngeal collapsibility correlated with body mass index (p<O.001), whereas the airway size did not. The velopharyngeal collapsibility was more pronounced in patients with frequent episodes of arterial oxyhaemoglobin desaturation during sleep. Velopharyngeal collapsibility associated with high body mass index was the important determinant of nocturnal breathing disturbances. Digital fluoroscopy displays the dynamic changes of the upper airways throughout the respiratory cycle.

Postural changes in respiratory airflow pressure and resistance in nasal, hypopharyngeal, and pharyngeal airway in normal subjects

We investigated the effect of posture on nasal and pharyngeal resistance in 12 healthy subjects studied during wakefulness. Airway pressure and airflow were measured with subjects seated and in dorsal and left lateral recumbency, during inspiration and expiration. We found that pharyngeal resistance was approximately four to six times lower than the nasal resistance. Only pharyngeal resistance was significantly increased upon assumption of a supine posture, from 0.02 +/- 0.01 Pa/mL per second when seated to 0.06 +/- 0.05 Pa/mL per second in dorsal recumbency and to 0.05 +/- 0.04 Pa/mL per second in left lateral recumbency. Mean nasal and pharyngeal resistances doubled upon assumption of a supine posture, but this difference was not statistically significant. There was no significant difference in pharyngeal resistance between inspiration and expiration. Finally, there was a strong linear relationship between pharyngeal pressure and pharyngeal resistance (r = .98, p<.0001). We concluded that in normal awake subjects 1) pharyngeal resistance increases with assumption of a supine posture, 2) the walls of the pharynx are not compliant enough to alter their resistance in response to inspiratory and expiratory pressure changes, and 3) it may be possible to infer pharyngeal resistance from measurements of pressure alone, without measurement of airflow.

Effect of blood pressure changes on air flow dynamics in the upper airway of the decerebrate cat

BACKGROUND

Previous studies suggest that upper airway neuromuscular activity can be affected by changes in blood pressure via a baroreceptor-mediated mechanism. It was hypothesized that increases in blood pressure would increase upper airway collapsibility predisposing to airway obstruction at a flow-limiting site in the hypopharynx.

METHODS

To examine the effect of blood pressure on upper airway function, maximal inspiratory air flow was determined through the isolated feline upper airway before, during, and after intravenous infusion of phenylephrine (10-20 micrograms.kg-1.min) in six decerebrate, tracheotomized cats. Inspiratory flow, hypopharyngeal pressure, and pressure at the site of pharyngeal collapse were recorded as hypopharyngeal pressure was rapidly decreased to achieve inspiratory flow limitation in the isolated upper airway. Pressure-flow relationships were used to determine maximal inspiratory air flow and its mechanical determinants, the upper airway critical pressure (a measure of pharyngeal collapsibility), and the nasal resistance upstream to the site of flow limitation.

RESULTS

An increased mean arterial blood pressure of 71 +/- 16 mmHg (mean +/- SD) was associated with significant decrease in maximal inspiratory air flow from 147 +/- 38 ml/s to 115 +/- 27 ml.sec-1 (P < 0.01). The decrease in maximal inspiratory air flow was associated with an increase in upper airway critical pressure from -8.1 +/- 3.8 to -5.7 +/- 3.7 cm H2O (p < 0.02), with no significant change in nasal resistance. When blood pressure was decreased to baseline by discontinuing the phenylephrine infusion, maximal inspiratory air flow and upper airway critical pressure returned to their baseline values.

CONCLUSIONS

Increased blood pressure increased the severity of upper airway air flow obstruction by increasing pharyngeal collapsibility. Previous studies relating baroreceptor activity to neuromuscular regulation of upper airway tone, are consistent with this effect being mediated by afferent activity from baroreceptors. These findings warrant further study because they suggest the possibility that upper airway obstruction in postoperative patients could either be caused or exacerbated by an increase in blood pressure.

A comparison between two methods of measuring pressure in the pharyngeal airway: transducer probe versus open catheter

A new multi-transducer probe system for measuring pharyngeal pressures was compared with an established open catheter system. Pharyngeal pressure measurements were made at the same time, and site, in subjects awake, at unmodified and with artificially increased nasal airway resistances, and during sleep documented by polysomnography. The two systems yielded almost identical results. It is anticipated that the multi-transducer probe system will prove of clinical value.

Effect of aging on the deglutitive oral, pharyngeal, and esophageal motor function

Aging affects some members of the swallowing orchestra and spares the others. It seems that changes in the pharynx of the elderly are more of a positive nature than a negative one and reflect an adaptation to age-induced structural changes of the upper esophageal sphincter. In the esophagus, the positive change in deglutitive peristaltic amplitude and duration seem to revert to a negative one over the age of 90 years. In the upper esophageal sphincter, it appears that aging reduces the resting pressure, but spares its response to various stimuli. Considering the increasing elderly population and their medical needs, further normalcy data about various manometric aspects of deglutition is needed for physiologic studies as well as diagnostic and therapeutic purposes.

Manometric evaluation of the pharynx

Over the past few years, studies of manometric techniques have improved our ability to accurately assess pharyngeal pressure events during swallowing. Solid-state transducers, circumferentially recording transducers, and on-line computer interpretation allow quantitative measurements. Studies in normal subjects will permit better recognition of pathologic states.

Afferent pathway(s) for pharyngeal dilator reflex to negative pressure in man: a study using upper airway anaesthesia

1. To determine the afferent pathways mediating pharyngeal dilator muscle activation in response to negative airway pressure in man, we recorded genioglossus electromyogram (EMG) activity (via intra-oral bipolar surface electrodes) in response to 500 ms duration pressure stimuli of -15 and -25 cm H2O in normal, conscious, supine subjects relaxed at end-expiration; responses were compared before and after upper airway anaesthesia. 2. Six rectified and integrated EMG responses were bin averaged for pressure stimuli applied with the glottis open (GO) and closed (GC) and to the outside of the face only (controls). Response magnitude was quantified as the ratio of the EMG activity for an 80 ms post-stimulus period (before the subject's reaction time for tongue protrusion) to an 80 ms pre-stimulus period. 3. In eight subjects, upper airway anaesthesia reduced the EMG responses with GC to a level indistinguishable from controls. After anaesthesia, responses with GO remained higher than those with GC. 4. With GC, the mean EMG responses decreased by 43% after selective anaesthesia of the nasal mucosa (trigeminal nerves) in two subjects, 32% after selective anaesthesia of the laryngeal mucosa (superior laryngeal nerves) in six subjects and by 21% after selective anaesthesia of the oropharyngeal mucosa (glossopharyngeal and lingual nerves) in four subjects. 5. We conclude that upper airway afferents mediate pharyngeal dilator muscle activation in response to negative pressure with GC and that subglottal receptors caused the increased activation with GO. With GC, the trigeminal and superior laryngeal nerves mediate an important component of the responses with the glossopharyngeal nerves playing a less important role.