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Biomedical subjects

R Shaker

Publications and source records attributed to R Shaker.

At least 91 records · Page 5Linked to original sources
PubMed1997

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.

Aged↗
PubMed1997

Correlation of electrical and contractile activities of the cricopharyngeus muscle in the cat.

We correlated the electrical and contractile activities of the cricopharyngeus (CP) to better understand the function of the CP and the upper esophageal sphincter (UES). In 40 decerebrate cats, we recorded resting and active tension of the CP and CP force and electromyographic (EMG) activity simultaneously during electrical stimulation of the pharyngoesophageal (PE) nerve, esophageal distension, or swallowing. In six intact cats, the change in diameter of the UES during food swallows was determined in two planes using videofluoroscopy. We found that resting tension of the CP developed quickly with stretch, and the strain-energy function, y = 6.5e3.4(z-1), fit (r = 0.94 +/- 0.06) this relationship. Active tension peaked at 1.68 +/- 0.03 times resting length, which is greater than the maximum distension during swallowing. Activation and relaxation of the CP occurred in approximately 50 and 120 ms, respectively. PE nerve stimulation bilaterally caused a force equal to approximately 90% of the summed force generated by separate stimulation of each PE nerve. The magnitude of the EMG response of the contralateral CP was approximately 18% of the ipsilateral response to unilateral PE nerve stimulation. We conclude that the CP exhibits tension throughout its physiological range of stretch. The CP functions more like a bilateral than a single contiguous muscle, and more like cardiac than striated muscle with regard to its passive elastic properties.

Animals↗
PubMed1997

Characterization of the pharyngo-UES contractile reflex in humans.

Preliminary human studies suggest the presence of an upper esophageal sphincter (UES) contractile reflex triggered by pharyngeal water stimulation. The purposes of this study were to further characterize this reflex and determine the threshold volume for its activation. We studied 10 healthy young volunteers by manometric technique before and after topical pharyngeal anesthesia. UES pressure responses to various volumes and temperatures of water injected into the pharynx were elucidated. At a threshold volume, rapid-pulse and slow continuous pharyngeal water injection resulted in significant augmentation of UES pressure in all volunteers. Threshold volume for inducing UES contraction averaged 0.1 +/- 0.01 ml for rapid-pulse injection and was significantly smaller than that for slow continuous injection (1.0 +/- 0.2 ml). UES pressure increase duration averaged 16 +/- 4 s. Augmentation of UES resting tone by injection of water with three different temperatures was similar. This augmentation was abolished after topical anesthesia. Conclusions were that stimulation of the human pharynx by injection of minute amounts of water results in a significant increase in resting UES pressure: the pharyngo-UES contractile reflex. The magnitude of pressure increase due to activation of this reflex is not volume or temperature dependent. Loss of pharyngeal sensation abolishes this reflex.

Adult↗
PubMed1996

A comparative study of unsedated transnasal esophagogastroduodenoscopy and conventional EGD.

BACKGROUND: A significant portion of the cost and complications associated with conventional esophagogastroduodenoscopy (EGD) is attributed to conscious intravenous sedation, which usually results in loss of work on the day of the endoscopy. Earlier studies have described the feasibility and safety of unsedated transnasal EGD in normal volunteers. METHODS: We compared the diagnostic yield and patient acceptability of this new technique performed first, with conventional EGD performed second in 24 outpatients. RESULTS: The sensitivity of transnasal EGD was 89% and its specificity was 97%. Transnasal EGD was more acceptable and less stressful to the patients than conventional EGD (p < 0.05). Oxygen saturation and blood pressure did not change during transnasal EGD. CONCLUSION: Transnasal EGD is feasible, safe, and well tolerated by patients. Specificity of transnasal EGD is similar to, but its sensitivity is lower than, conventional EGD. By eliminating the need for sedation-related work loss and postprocedural monitoring, transnasal EGD potentially is more cost-effective than conventional EGD.

Adult↗
PubMed1996

Inhibition of progressing primary esophageal peristalsis by pharyngeal water stimulation in humans.

BACKGROUND & AIMS: Sensory impulses initiated from the pharynx exert differing effects on the deglutitive apparatus. They have an inhibitory effect on the lower esophageal sphincter but an excitatory effect on the upper esophageal sphincter. The aim of this study was to systematically investigate the effect of pharyngeal sensory impulses evoked by water stimulation on the progressing esophageal peristalsis. METHODS: Sixteen healthy young volunteers were studied in the supine position. The presence of normal peristalsis was verified. Esophageal peristalsis was recorded 3, 6, 9, 12, 15, and 18 cm above the lower esophageal sphincter. Pharyngeal stimulation was performed by injecting a predetermined threshold volume into the pharynx 2 cm above the upper esophageal sphincter, directed posteriorly. The injections were timed to coincide with the arrival of the peristaltic wave induced by dry swallows at respective recording sites. RESULTS: Injection of the threshold volume (0.5 +/- 0.1 mL) stopped the progression of peristalsis at both the striated and smooth muscle esophagus. Topical pharyngeal anesthesia blocked this inhibitory effect (P < 0.01). CONCLUSIONS: Sensory impulses initiated from the pharynx evoked by water injection inhibit the progression of primary esophageal peristalsis. Although the clinical significance of these findings is not determined, they may explain the mechanism of some of the failed esophageal peristalsis.

Adult↗
PubMed1996

Characteristics of lower esophageal sphincter relaxation induced by pharyngeal stimulation with minute amounts of water.

BACKGROUND & AIMS: Injection of minute amounts of water in the pharynx leads to a long-duration lower esophageal sphincter (LES) relaxation that is an important feature of a transient LES relaxation. The aims of this study were to determine if a pharyngeal stimulus-induced LES relaxation is associated with crural diaphragm inhibition, esophageal common cavity, and acid reflux in normal subjects. METHODS: Esophageal and LES pressure, crural diaphragm electromyographs, and pH were recorded in the fasting and postprandial states in normal subjects. The pharynx was stimulated by injection of water at bolus volumes of 0.05 and 0.1 mL and then in 0.1-mL increments. RESULTS: Pharyngeal stimulation induced a long-duration LES relaxation in the absence of swallow and esophageal peristalsis. In the fasting state, none of the LES relaxations induced by pharyngeal stimulation were associated with inhibition of crural diaphragm, esophageal common cavity, and acid reflux. In the postprandial periods, only 8% of the pharyngeal stimuli resulted in crural diaphragm inhibition and esophageal common cavity. Esophageal reflux was found only at the times of simultaneous LES and crural diaphragm relaxation. CONCLUSIONS: Stimulation of the pharynx has different effects on the LES and crural diaphragm. Relaxation of crural diaphragm along with LES relaxation is essential for the occurrence of gastroesophageal reflux in normal subjects.

Adult↗
PubMed1996

Initiation of esophageal secondary peristalsis by slow fluid infusion in the opossum: effect of hydrochloric acid.

We investigated the mechanisms of slow fluid infusion-induced secondary peristalsis and the effects of hydrochloric acid on this response. In 13 chronically esophagostomized opossum, acidic and neutral barium sulfate were infused into the distal esophagus at a rate of 1.1 ml/min, while recording the esophageal dimension by videofluoroscopy and esophageal intraluminal pressure concurrently. The effects of atropine, tetrodotoxin, capsaicin, and bilateral cervical vagotomy on the response to slow fluid infusion were examined. Acidic barium initiated secondary peristalsis more frequently and at shorter latency with less increase of preperistaltic intraesophageal pressure than neutral barium (P < 0.05). Atropine abolished secondary peristalsis initiated by neutral barium. For acidic barium, atropine decreased the incidence of secondary peristalsis, increased the latency for initiation of secondary peristalsis, and initiated secondary peristalsis more distally (P < 0.05). Tetrodotoxin or vagotomy and capsaicin abolished activation of secondary peristalsis. We concluded that secondary peristalsis can be stimulated in response to slow distension by minute amounts of fluid. This peristalsis is atropine and capsaicin sensitive and vagally mediated. The presence of acid significantly lowers the threshold for stimulation of secondary peristalsis induced by slow fluid distension. This effect seems to be atropine resistant.

Animals↗
PubMed1996

Kinematic and dynamic characteristics of solid pellet movement during the pharyngeal phase of swallowing.

Information on solid particle movement through the pharynx, in addition to its physiologic importance, has relevance to the swallowing of medications in pill form. The purpose of this study was to determine the kinematics of a solid particle during the oral-pharyngeal phase of swallowing. We used a concurrent manometric-videofluoroscopic technique and identified two distinct zones of increasing bolus velocity, one at the tongue base and the other at the pharyngo-upper esophageal sphincter (UES) region. Velocity decreased significantly (p < .05), to 9.0 +/- 1.0 cm/s, while the bolus traversed the area located between the tip of the horizontal epiglottis and the pharyngeal wall. The velocity of the liquid barium bolus head was similar to that of the solid barium pellet. The average bolus tail velocity was relatively constant. The acceleration of the barium pellet was temporally associated with development of an incrementally decreasing pressure distal to the location of the pellet in the hypopharynx and across the UES. In conclusion, the kinematics of a solid particle are similar to those of the head of a liquid bolus, but both are different from bolus tail kinematics. During the pharyngeal phase of swallowing, the area located ahead of the bolus exhibits an incrementally decreasing pressure, caudally. This may facilitate bolus transport and contribute to airway protection.

Adult↗
PubMed1996

Enterogastric bile reflux during technetium-99m-sestamibi cardiac imaging.

UNLABELLED: Enterogastric bile reflux (EGBR), a risk factor for both gastritis and esophagitis, is a potentially treatable noncoronary cause for chest pain. METHODS: To investigate the frequency of EGBR during different 99mTc-sestamibi cardiac imaging, 1405 consecutive 99mTc-sestamibi SPECT myocardial perfusion studies were reviewed. RESULTS: One hundred sixteen of the 1405 patient studies (8.3%) showed EGBR with roughly equal numbers of patients having marked (43 patients), moderate (38 patients) or minimal (35 patients) intensity of abnormal gastric activity. Two examinations showed gastroesophageal reflux of activity. EGBR was less frequent with treadmill stress testing (5.5% patients) than with pharmacologic stress testing using either dipyridamole (11% of patients) or dobutamine (9.2% of patients) (p > 0.005). EGBR also was more frequent in patients over 40 yr of age. Finally, the prevalence of upper gastrointestinal symptoms and the frequency of established upper gastrointestinal diagnoses correlated strongly with the presence and intensity of EGBR. CONCLUSION: Clarification of the full clinical significance of EGBR during 99mTc-sestamibi cardiac imaging is a topic for future research. Nonetheless, the imaging finding of EGBR may, in fact, identify a potentially treatable noncoronary cause for chest pain.

Bile Reflux↗
PubMed1996

Esophageal intramural pseudodiverticulosis associated with achalasia.

Esophageal intramural pseudodiverticulosis (EIPD) is a rare condition in which multiple small outpouchings are seen in the wall of the esophagus. Although EIPD is typically associated with esophageal narrowing, only a few cases have been described in which it was associated with esophageal dysmotility. We report the case of a 52-yr-old female who presented with dysphagia and who had EIPD protruding from a 5-cm-long concentric distal esophageal stricture, with a markedly dilated upper and middle third of the esophagus. The short segment of the esophagus between the stricture and the lower esophageal sphincter also was dilated. Barium column was held up above a nonrelaxing lower esophageal sphincter that opened after inhalation of amylnitrate. Esophageal manometry confirmed the presence of vigorous achalasia. Although EIPD has been associated with several other conditions, this is the first report of an association with achalasia.

Deglutition Disorders↗
PubMed1996

Coordination of deglutitive vocal cord closure and oral-pharyngeal swallowing events in the elderly.

OBJECTIVE: The temporal relationship between deglutitive glottic closure, oropharyngeal bolus transit and other biomechanical swallowing events was studied in 10 healthy elderly subjects by concurrent transnasal videolaryngoscopy, videofluoroscopy, intraluminal pharyngeal manometry and submental electromyography. The results were compared with those of a similar study in a group of young healthy volunteers published previously. RESULTS: Overall, the coordination of various deglutitive biomechanical events in the elderly group was found to be similar to that in the young. However, subtle differences were documented. Contrary to historical young controls, where the onset of the bolus movement from the mouth toward the pharynx invariably occurred after the vocal cords reached their maximum adduction, in the elderly this relationship was variable. In all swallows of two subjects it occurred 0.41 +/- 0.2 s after, and in another two it occurred 0.08 +/- 0.06 s before the maximal vocal cord adduction. Six subjects showed interchanging patterns. Except for the above-mentioned changes, the onset of vocal cord adduction in the elderly also preceded all other studied events, similar to previously published data in the young. In the elderly, the total duration between onset of vocal cord adduction and their complete reopening (2.47 +/- 0.1 s) was similar to that in the young. CONCLUSION: Although subtle alterations occur in the coordination of deglutitive vocal cord closure and oropharyngeal bolus transit in some elderly people, the overall coordination between airway protection and the transit aspect of the oral-pharyngeal phase of swallowing is preserved in the elderly.

Aged↗
PubMed1995

Airway protective mechanisms: current concepts.

There are at least eight mechanisms identified that result either in volume clearance of the pharynx and esophagus (secondary peristalsis and pharyngeal swallow) or prevent entry of the gastric content into the esophagus and pharynx (LES and UES), accentuate these barriers (esophago-UES and pharyngo-UES contractile reflexes), or induce closure of the vocal cords and introitus to the trachea (esophagoglottal and pharyngoglottal reflexes). The sum effect of various combinations of these mechanisms is suggested to help prevent retrograde aspiration. In other words, airway protective mechanisms against retrograde aspiration are multifactorial and involve delicate interaction between upper GI and upper airway tracts. Although the existence of these mechanisms in normal volunteers has been documented, their function in patients with retrograde aspiration and supraesophageal complications of gastroesophageal reflux disease currently awaits investigation.

Airway Obstruction↗
PubMed1995

Inhibition of resting lower esophageal sphincter pressure by pharyngeal water stimulation in humans.

BACKGROUND/AIMS: Normal inhibition of lower esophageal sphincter (LES) tone occurs during swallowing and belching. However, it is known that it may occur independently of these functions. The aim of this study was to characterize the effect of pharyngeal water stimulation on resting LES pressure. METHODS: The effect of rapid-pulse and slow continuous intrapharyngeal injection of minute increments of water on the resting tone of the upper and LES of 14 healthy young volunteers was evaluated by concurrent manometry, submental electromyography, and respirography. RESULTS: At a threshold volume, pharyngeal water injection induced an isolated LES relaxation in all volunteers. The threshold volume inducing LES relaxation by rapid-pulse injection, 0.16 +/- 0.01 mL, was significantly lower than that with slow continuous injection (0.5 +/- 0.05 mL) (P < 0.05). The duration and magnitude of LES relaxation were not volume dependent. The duration of LES relaxation induced by rapid-pulse injection was significantly longer than that of swallows. CONCLUSIONS: Minute amounts of liquid injected into the pharynx induce LES relaxation different from that of the normal swallow. Neither the duration nor the magnitude of this relaxation is volume dependent. Whereas the contribution of this finding to the mechanism of transient LES relaxation remains to be ascertained, it may partially explain the variability of the basal LES pressure.

Adult↗
PubMed1995

Esophagopharyngeal distribution of refluxed gastric acid in patients with reflux laryngitis.

BACKGROUND & AIMS: A variety of otolaryngological abnormalities have been attributed to the contact of gastroesophageal refluxate with respective structures of the aerodigestive tract. The aim of this study was to determine and compare the pharyngoesophageal distribution of gastric acid refluxate between patients with proven laryngitis attributed clinically to gastroesophageal reflux and three control groups. METHODS: An ambulatory 24-hour simultaneous three-site pharyngoesophageal pH monitoring technique was used to measure reflux parameters in the pharynx, proximal esophagus, and distal esophagus. RESULTS: Between-group comparison showed no significant difference in the reflux parameters in the distal esophagus between the studied groups. A significantly higher percentage of distal reflux episodes reached the proximal esophagus in the laryngitis group than in the control groups (P < 0.01), and the number of pharyngeal reflux episodes and time of acid exposure were significantly higher in the laryngitis group than in the control groups (P < 0.001). CONCLUSIONS: Compared with normal controls and patients with gastroesophageal reflux disease, pharyngeal reflux of gastric acid is significantly more prevalent and the ratio of proximal to distal esophageal acid reflux episodes is significantly increased in patients with posterior laryngitis. Simultaneous three-site ambulatory pharyngoesophageal pH monitoring may provide supporting evidence when the diagnosis of reflux-induced aerodigestive tract lesions is considered.

Adult↗
PubMed1995

Deglutitive aspiration in patients with tracheostomy: effect of tracheostomy on the duration of vocal cord closure.

BACKGROUND/AIMS: Deglutitive aspiration in patients with tracheostomy has been attributed to impaired laryngeal movement, loss of protective laryngeal reflexes, and uncoordinated laryngeal closure. The aim of this study was to determine the effect of tracheostomy on the duration of deglutitive vocal cord closure. METHODS: Using concurrent videoendoscopy, respirography, and submental electromyography, deglutitive vocal cord closure and its temporal relationship with deglutitive apnea was compared between patients with tracheostomy and normal volunteers. RESULTS: Between-group comparison showed that the duration of vocal cord adduction/abduction in patients with tracheostomy was significantly shorter than that of normal volunteers (P < 0.05). Contrary to normal volunteers, in patients with tracheostomy, 5-mL water swallows significantly increased the duration of vocal cord adduction/abduction compared with that of dry swallows (P < 0.05). In addition, in patients with tracheostomy, deglutitive apnea and submental electromyography were not coordinated with vocal cord kinetics. CONCLUSIONS: Although the vocal cords close completely during swallowing in patients with tracheostomy, their duration of closure is significantly shorter compared with normal volunteers. Coordination of deglutitive vocal cord kinetics, apnea, and submental electromyography is altered in patients with tracheostomy. Contrary to normal controls, duration of deglutitive vocal cord closure in patients with tracheostomy is modified by the presence of liquid bolus.

Adult↗
PubMed1995

Effect of aging on the secondary esophageal peristalsis: presbyesophagus revisited.

In this study we determined the effect of aging on the capability of the human esophagus to generate secondary peristalsis. We studied nine healthy young (35 +/- 2 yr, 25-45 yr) and nine healthy elderly (74 +/- 3 yr, 70-83 yr) volunteers. We stimulated secondary peristalsis by intraesophageal air injection and balloon distension. All young volunteers exhibited secondary esophageal peristalsis. In four elderly volunteers, secondary peristalsis could not be elicited with injection of any of the tested air volumes. Frequency of stimulation of secondary peristalsis and lower esophageal sphincter (LES) relaxation in response to intraesophageal air distension in the elderly was significantly lower than that in the young (P < 0.01). Stimulation of secondary peristalsis by balloon distension was less consistent compared with the air injection. In conclusion, 1) in the elderly, compared with the young, secondary esophageal peristalsis is either absent or is evoked less frequently after esophageal distension, and complete LES relaxation in response to esophageal air distension is less frequent, and 2) in both young and elderly, secondary esophageal peristalsis is induced more frequently after generalized esophageal distension by air than its segmental distension by a balloon.

Adult↗