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Sandra Nuyts - One of the best experts on this subject based on the ideXlab platform.
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dysphagia after chemoradiotherapy for head and neck squamous cell carcinoma dose effect relationships for the swallowing structures
International Journal of Radiation Oncology Biology Physics, 2009Co-Authors: Piet Dirix, Sarah Abbeel, Bianca Vanstraelen, Robert Hermans, Sandra NuytsAbstract:Purpose To evaluate late dysphagia after chemoradiotherapy for locally advanced head-and-neck squamous cell carcinoma, and to examine its correlation with clinical and dosimetric parameters. Methods and Materials Consecutive patients, treated with radiotherapy (70–72 Gy) and concomitant chemotherapy (cisplatinum 100 mg/m 2 every 3 weeks) between 2004 and 2007, were examined. Swallowing was evaluated by four quality-of-life questionnaires: EORTC C30 and HN mean follow-up was 20.4 months (range, 6–45 months). The volume of the middle Pharyngeal Constrictor muscle receiving ≥50 Gy ( p = 0.04), the mean dose to this structure ( p = 0.02) and to the supraglottic larynx ( p = 0.04) were significantly associated with late swallowing problems at univariate analysis, along with tumor localization ( p = 0.008), T-classification ( p = 0.02), and pretreatment swallowing problems ( p = 0.01). Only this last factor significantly correlated with late dysphagia at multivariate analysis. Conclusion These findings motivate further efforts to reduce the dose to the swallowing structures, especially to the Pharyngeal Constrictor muscles and the larynx. However, clinical parameters are also important and should be included in future prospective trials.
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dysphagia after chemoradiotherapy for head and neck squamous cell carcinoma dose effect relationships for the swallowing structures
International Journal of Radiation Oncology Biology Physics, 2009Co-Authors: Piet Dirix, Sarah Abbeel, Bianca Vanstraelen, Robert Hermans, Sandra NuytsAbstract:Purpose To evaluate late dysphagia after chemoradiotherapy for locally advanced head-and-neck squamous cell carcinoma, and to examine its correlation with clinical and dosimetric parameters. Methods and Materials Consecutive patients, treated with radiotherapy (70–72 Gy) and concomitant chemotherapy (cisplatinum 100 mg/m 2 every 3 weeks) between 2004 and 2007, were examined. Swallowing was evaluated by four quality-of-life questionnaires: EORTC C30 and HN mean follow-up was 20.4 months (range, 6–45 months). The volume of the middle Pharyngeal Constrictor muscle receiving ≥50 Gy ( p = 0.04), the mean dose to this structure ( p = 0.02) and to the supraglottic larynx ( p = 0.04) were significantly associated with late swallowing problems at univariate analysis, along with tumor localization ( p = 0.008), T-classification ( p = 0.02), and pretreatment swallowing problems ( p = 0.01). Only this last factor significantly correlated with late dysphagia at multivariate analysis. Conclusion These findings motivate further efforts to reduce the dose to the swallowing structures, especially to the Pharyngeal Constrictor muscles and the larynx. However, clinical parameters are also important and should be included in future prospective trials.
Samuel T Kuna - One of the best experts on this subject based on the ideXlab platform.
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respiratory related activation and mechanical effects of the Pharyngeal Constrictor muscles
Respiration Physiology, 2000Co-Authors: Samuel T KunaAbstract:We have examined the respiratory-related activation of Pharyngeal Constrictor (PC) muscles in decerebrate cats, normal adult humans and patients with obstructive sleep apnea. In decerebrate cats and awake normal adult humans, phasic expiratory PC activity is uniformly present under hypercapnic and hypoxic conditions. While the PC muscles are electrically silent during quiet breathing in normal adult humans in NREM sleep, an activation pattern very similar to that of other upper airway dilators, such as the genioglossus muscle, is present during spontaneous and induced apneas in patients with obstructive sleep apnea. Experiments using an isolated, sealed upper airway preparation in decerebrate cat show that selective activation of the PC muscles stiffens the Pharyngeal airway. The results also show that activation of the PC muscles constricts the airway at relatively high airway volumes but dilates the airway at relatively low airway volumes. These results suggest that PC muscle activation at the end of an apneic episode, when airway volume is relatively low, may help restore airway patency in patients with obstructive sleep apnea.
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respiratory related Pharyngeal Constrictor muscle activity in decerebrate cats
Journal of Applied Physiology, 1997Co-Authors: Samuel T Kuna, Christi R VanoyeAbstract:Kuna, Samuel T., and Christi R. Vanoye.Respiratory-related Pharyngeal Constrictor muscle activity in decerebrate cats. J. Appl. Physiol.83(5): 1588–1594, 1997.—Respiratory-related activity of the h...
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Respiratory-related Pharyngeal Constrictor muscle activity in normal human adults.
American journal of respiratory and critical care medicine, 1997Co-Authors: Samuel T Kuna, J S Smickley, C. R. VanoyeAbstract:Electromyographic activity of the superior, middle, and inferior Pharyngeal Constrictor (PC) muscles was examined in 10 normal adult humans during wakefulness and sleep. Wire electrodes were inserted close to the midline of the posterior Pharyngeal wall at the level of the soft palate (superior PC), tip of the epiglottis (middle PC), and corniculate tubercle (inferior PC). In general, the three PC muscles exhibited similar patterns of activation. The PCs were activated during swallows, repetitive "pa" sounds, changes in head position, and the last portions of slow inspiratory and expiratory vital capacity maneuvers. Respiratory-related PC activity was infrequent during quiet breathing during wakefulness; variable and inconsistent phasic activation in expiration in one or more of the PCs was present in seven of the 10 subjects, particularly after a swallow. Progressive hyperoxic hypercapnia and progressive isocapnic hypoxia were associated with recruitment of phasic PC activity, which was predominantly exp...
Olle Ekberg - One of the best experts on this subject based on the ideXlab platform.
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An In Vitro Model for Studying Neuromuscular Transmission in the Mouse Pharynx
Dysphagia, 2009Co-Authors: Olle Ekberg, M. Ekman, L. I. Eriksson, R. Malm, E. Sundman, A. ArnerAbstract:The muscles of the pharynx are controlled by networks of neurons under the control of specific regions in the brain stem, which have been fairly well studied. However, the transmission between these neurons and the Pharyngeal muscles, at the motor end plates, is less well understood. Therefore, an in vitro model for the study of neuromuscular transmission in the Pharyngeal muscle of the mouse was developed. Ring preparations from the inferior Constrictor and the cricopharyngeus muscles were isolated and mounted for isometric force recording at physiologic temperature. Preparations from the diaphragm and the soleus muscles were examined in parallel. The muscles were stimulated at supramaximal voltage with short tetani at 100 Hz. Following direct stimulation of the muscle fibers, using a longer pulse duration, the rate of force development of the Pharyngeal muscles was similar to that of the diaphragm and faster than that of the soleus muscle. By varying the duration of the stimulation pulses, conditions where the nerve-mediated activation contributed to a major extent of the contractile responses were identified. Gallamine completely inhibited the nerve-mediated responses. In separate experiments the dose dependence of gallamine inhibition was examined, showing similar sensitivity in the inferior Pharyngeal Constrictor compared to the diaphragm and soleus muscles. We conclude that reproducible contractile responses with an identifiable nerve-induced component can be obtained from the mouse inferior Pharyngeal Constrictor. The Pharyngeal muscles have contractile characteristics similar to those of the faster diaphragm. The sensitivity to the neuromuscular blocking agent gallamine of the inferior Pharyngeal Constrictor was in the same concentration range as that of the diaphragm and soleus muscles.
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acetylcholine receptor density in human cricoPharyngeal muscle and Pharyngeal Constrictor muscle
Acta Anaesthesiologica Scandinavica, 2002Co-Authors: Eva Sundman, Olle Ekberg, C S Yost, G Margolin, Richard Kuylenstierna, Lars ErikssonAbstract:Background: Upper esophageal sphincter resting tone is reduced during partial neuromuscular block, whereas contraction of the Pharyngeal Constrictor muscle is only slightly affected. We hypothesized that this difference may arise from differential nicotinic acetylcholine receptor (nAChR) density, the density supposedly being lower in the more sensitive cricoPharyngeal muscle than in the resistant Pharyngeal Constrictor muscle. The aim of this study was to determine the density of nAChR in the main component of the upper esophageal sphincter, the cricoPharyngeal muscle, and in the Pharyngeal Constrictor muscle. Methods: After approval by the institutional ethics committee and informed consent, muscle specimens were obtained from five patients undergoing surgery with laryngectomy for malignancies of the larynx or thyroid gland. None had received radiation therapy to the affected area. The nAChR from these tissue specimens were solubilized and incubated with I-125-alpha-bungarotoxin. The quantity of radioligand-receptor complex was measured by radioactive decay in a liquid scintillation counter. The receptor density was expressed as femtomoles per milligram of protein (fmol/mg protein). Results: The nAChR density was determined to 6.8 (3.5) fmol/mg protein (mean (SD)) in the cricoPharyngeal muscle and 5.6 (2.1) fmol/mg protein in the Pharyngeal Constrictor muscle (P = 0.22). Although we could not find any difference in mean nAChR density, contrary to our hypothesis, the density in four of the five patients was higher in the cricoPharyngeal muscle than in the Pharyngeal Constrictor muscle. Conclusion: Our results indicate that the density of nicotinic acetylcholine receptors is similar in the cricoPharyngeal muscle and in the Pharyngeal Constrictor muscle. Nicotinic acetylcholine receptor density, as determined by I-125-alpha-bungarotoxin assay, cannot explain the difference in response to neuromuscular blocking drugs between the investigated muscles.
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the incidence and mechanisms of Pharyngeal and upper esophageal dysfunction in partially paralyzed humans Pharyngeal videoradiography and simultaneous manometry after atracurium
Anesthesiology, 2000Co-Authors: Eva Sundman, Olle Ekberg, Richard Kuylenstierna, Rolf Olsson, Hanne Witt, Lars I ErikssonAbstract:BACKGROUND: Residual neuromuscular block caused by vecuronium alters Pharyngeal function and impairs airway protection. The primary objectives of this investigation were to radiographically evaluate the swallowing act and to record the incidence of and the mechanism behind Pharyngeal dysfunction during partial neuromuscular block. The secondary objective was to evaluate the effect of atracurium on Pharyngeal function. METHODS: Twenty healthy volunteers were studied while awake during liquid-contrast bolus swallowing. The incidence of Pharyngeal dysfunction was studied by fluoroscopy. The initiation of the swallowing process, the Pharyngeal coordination, and the bolus transit time were evaluated. Simultaneous manometry was used to document pressure changes at the tongue base, the Pharyngeal Constrictor muscles, and the upper esophageal sphincter. After control recordings, an intravenous infusion of atracurium was administered to obtain train-of-four ratios (T4/T1) of 0.60, 0.70, and 0.80, followed by recovery to a train-of-four ratio of more than 0.90. RESULTS: The incidence of Pharyngeal dysfunction was 6% during the control recordings and increased (P < 0.05) to 28%, 17%, and 20% at train-of-four ratios 0.60, 0.70, and 0.80, respectively. After recovery to a train-of-four ratio of more than 0.90, the incidence was 13%. Pharyngeal dysfunction occurred in 74 of 444 swallows, the majority (80%) resulting in laryngeal penetration. The initiation of the swallowing reflex was impaired during partial paralysis (P = 0.0081). The Pharyngeal coordination was impaired at train-of-four ratios of 0.60 and 0.70 (P < 0.01). A marked reduction in the upper esophageal sphincter resting tone was found, as well as a reduced contraction force in the Pharyngeal Constrictor muscles. The bolus transit time did not change significantly. CONCLUSION: Partial neuromuscular paralysis caused by atracurium is associated with a four- to fivefold increase in the incidence of misdirected swallowing. The mechanism behind the Pharyngeal dysfunction is a delayed initiation of the swallowing reflex, impaired Pharyngeal muscle function, and impaired coordination. The majority of misdirected swallows resulted in penetration of bolus to the larynx. (Less)
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functional assessment of the pharynx at rest and during swallowing in partially paralyzed humans simultaneous videomanometry and mechanomyography of awake human volunteers
Anesthesiology, 1997Co-Authors: Lars I Eriksson, Olle Ekberg, Eva Sundman, Rolf Olsson, Lena Nilsson, Hanne Witt, Richard KuylenstiernaAbstract:BACKGROUND: Functional characteristics of the pharynx and upper esophagus, including aspiration episodes, were investigated in 14 awake volunteers during various levels of partial neuromuscular block. Pharyngeal function was evaluated using videoradiography and computerized Pharyngeal manometry during contrast bolus swallowing. METHODS: Measurements of Pharyngeal Constrictor muscle function (contraction amplitude, duration, and slope), upper esophageal sphincter muscle resting tone, muscle coordination, bolus transit time, and aspiration under fluoroscopic control (laryngeal or tracheal penetration) were made before (control measurements) and during a vecuronium-induced partial neuromuscular paralysis, at fixed intervals of mechanical adductor pollicis muscle train-of-four (TOF) fade; that is, at TOF ratios of 0.60, 0.70, 0.80, and after recovery to a TOF ratio > 0.90. RESULTS: Six volunteers aspirated (laryngeal penetration) at a TOF ratio 0.90 or during control recording. Pharyngeal Constrictor muscle function was not affected at any level of paralysis. The upper esophageal sphincter resting tone was significantly reduced at TOF ratios of 0.60, 0.70, and 0.80 (P 0.90 is reached. The upper esophageal sphincter muscle is more sensitive to vecuronium than is the Pharyngeal Constrictor muscle.
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Videomanometric aspects of Pharyngeal Constrictor activity
Dysphagia, 1996Co-Authors: Rolf Olsson, Olle Kjellin, Olle EkbergAbstract:Pressure changes were registered with videomanometry (simultaneous manometry and barium swallow) in the pharynx and in the pharyngoesophageal segment (PES) during swallowing. A considerable longitudinal asymmetry was found. Peak pressure was highest in the PES, lower in the inferior Constrictor area, and lowest at the level of the tongue base. The rate of pressure rise was highest at the level of the PES. The speed of propagation of the contraction wave was 13 (±2) cm/sec. There was no correlation between the measured variables (i.e., peak pressure, rate of pressure rise, and speed of contracting wave). Our findings can partly be explained by different mechanical constraints at different levels of the pharynx but may also reflect the organization of neural control of swallowing in the brainstem. Knowledge of transducer position and orientation is essential for the evaluation of Pharyngeal pressure during swallowing. Such knowledge is best achieved by performing manometry simultaneously with fluoroscopy, i.e., videomanometry.
Piet Dirix - One of the best experts on this subject based on the ideXlab platform.
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dysphagia after chemoradiotherapy for head and neck squamous cell carcinoma dose effect relationships for the swallowing structures
International Journal of Radiation Oncology Biology Physics, 2009Co-Authors: Piet Dirix, Sarah Abbeel, Bianca Vanstraelen, Robert Hermans, Sandra NuytsAbstract:Purpose To evaluate late dysphagia after chemoradiotherapy for locally advanced head-and-neck squamous cell carcinoma, and to examine its correlation with clinical and dosimetric parameters. Methods and Materials Consecutive patients, treated with radiotherapy (70–72 Gy) and concomitant chemotherapy (cisplatinum 100 mg/m 2 every 3 weeks) between 2004 and 2007, were examined. Swallowing was evaluated by four quality-of-life questionnaires: EORTC C30 and HN mean follow-up was 20.4 months (range, 6–45 months). The volume of the middle Pharyngeal Constrictor muscle receiving ≥50 Gy ( p = 0.04), the mean dose to this structure ( p = 0.02) and to the supraglottic larynx ( p = 0.04) were significantly associated with late swallowing problems at univariate analysis, along with tumor localization ( p = 0.008), T-classification ( p = 0.02), and pretreatment swallowing problems ( p = 0.01). Only this last factor significantly correlated with late dysphagia at multivariate analysis. Conclusion These findings motivate further efforts to reduce the dose to the swallowing structures, especially to the Pharyngeal Constrictor muscles and the larynx. However, clinical parameters are also important and should be included in future prospective trials.
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dysphagia after chemoradiotherapy for head and neck squamous cell carcinoma dose effect relationships for the swallowing structures
International Journal of Radiation Oncology Biology Physics, 2009Co-Authors: Piet Dirix, Sarah Abbeel, Bianca Vanstraelen, Robert Hermans, Sandra NuytsAbstract:Purpose To evaluate late dysphagia after chemoradiotherapy for locally advanced head-and-neck squamous cell carcinoma, and to examine its correlation with clinical and dosimetric parameters. Methods and Materials Consecutive patients, treated with radiotherapy (70–72 Gy) and concomitant chemotherapy (cisplatinum 100 mg/m 2 every 3 weeks) between 2004 and 2007, were examined. Swallowing was evaluated by four quality-of-life questionnaires: EORTC C30 and HN mean follow-up was 20.4 months (range, 6–45 months). The volume of the middle Pharyngeal Constrictor muscle receiving ≥50 Gy ( p = 0.04), the mean dose to this structure ( p = 0.02) and to the supraglottic larynx ( p = 0.04) were significantly associated with late swallowing problems at univariate analysis, along with tumor localization ( p = 0.008), T-classification ( p = 0.02), and pretreatment swallowing problems ( p = 0.01). Only this last factor significantly correlated with late dysphagia at multivariate analysis. Conclusion These findings motivate further efforts to reduce the dose to the swallowing structures, especially to the Pharyngeal Constrictor muscles and the larynx. However, clinical parameters are also important and should be included in future prospective trials.
Eva Sundman - One of the best experts on this subject based on the ideXlab platform.
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fiber type composition and fiber size of the human cricoPharyngeal muscle and the Pharyngeal Constrictor muscle
Acta Anaesthesiologica Scandinavica, 2004Co-Authors: Eva Sundman, G Margolin, Richard Kuylenstierna, T Ansved, Lars ErikssonAbstract:Background: Despite a similar density of nicotinic acetylcholine receptors, the upper esophageal sphincter is sensitive to partial neuromuscular block, whereas the Pharyngeal Constrictor muscle is more resistant. In order to postulate possible mechanisms behind this difference in pharmacological response, basic knowledge of morphological and physiological features of these muscles is needed. The aim of this study was to compare the muscle fiber-type composition, the size and the morphology of the muscle fibers of the cricoPharyngeal muscle, the main component of the upper esophageal sphincter, with that of the Pharyngeal Constrictor muscle. Methods: Muscle specimens were obtained from five patients undergoing surgery with laryngectomy. Muscle fiber type was determined by myosin heavy chain immunohistochemistry and the muscle fiber cross-sectional area was measured for each fiber type by planimetry. Morphology of muscle fibers was evaluated by histochemistry. Results: The muscle fiber cross-sectional area was generally smaller in the cricoPharyngeal muscle compared with the Pharyngeal Constrictor muscle (P < 0.001). The composition of fiber types showed a large interindividual variability with no distinct difference between the studied muscles. Aberrant histological features were common in both the cricoPharyngeal muscle and the Pharyngeal Constrictor muscle. Conclusion: The main morphological difference between the neuromuscular blocking agents sensitive cricoPharyngeal muscle and the more resistant Pharyngeal Constrictor muscle is a uniformly smaller size of contributing fiber types in the cricoPharyngeal muscle than in the Pharyngeal Constrictor muscle. The muscle fiber-type composition does not differ between the two studied muscles.
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acetylcholine receptor density in human cricoPharyngeal muscle and Pharyngeal Constrictor muscle
Acta Anaesthesiologica Scandinavica, 2002Co-Authors: Eva Sundman, Olle Ekberg, C S Yost, G Margolin, Richard Kuylenstierna, Lars ErikssonAbstract:Background: Upper esophageal sphincter resting tone is reduced during partial neuromuscular block, whereas contraction of the Pharyngeal Constrictor muscle is only slightly affected. We hypothesized that this difference may arise from differential nicotinic acetylcholine receptor (nAChR) density, the density supposedly being lower in the more sensitive cricoPharyngeal muscle than in the resistant Pharyngeal Constrictor muscle. The aim of this study was to determine the density of nAChR in the main component of the upper esophageal sphincter, the cricoPharyngeal muscle, and in the Pharyngeal Constrictor muscle. Methods: After approval by the institutional ethics committee and informed consent, muscle specimens were obtained from five patients undergoing surgery with laryngectomy for malignancies of the larynx or thyroid gland. None had received radiation therapy to the affected area. The nAChR from these tissue specimens were solubilized and incubated with I-125-alpha-bungarotoxin. The quantity of radioligand-receptor complex was measured by radioactive decay in a liquid scintillation counter. The receptor density was expressed as femtomoles per milligram of protein (fmol/mg protein). Results: The nAChR density was determined to 6.8 (3.5) fmol/mg protein (mean (SD)) in the cricoPharyngeal muscle and 5.6 (2.1) fmol/mg protein in the Pharyngeal Constrictor muscle (P = 0.22). Although we could not find any difference in mean nAChR density, contrary to our hypothesis, the density in four of the five patients was higher in the cricoPharyngeal muscle than in the Pharyngeal Constrictor muscle. Conclusion: Our results indicate that the density of nicotinic acetylcholine receptors is similar in the cricoPharyngeal muscle and in the Pharyngeal Constrictor muscle. Nicotinic acetylcholine receptor density, as determined by I-125-alpha-bungarotoxin assay, cannot explain the difference in response to neuromuscular blocking drugs between the investigated muscles.
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the incidence and mechanisms of Pharyngeal and upper esophageal dysfunction in partially paralyzed humans Pharyngeal videoradiography and simultaneous manometry after atracurium
Anesthesiology, 2000Co-Authors: Eva Sundman, Olle Ekberg, Richard Kuylenstierna, Rolf Olsson, Hanne Witt, Lars I ErikssonAbstract:BACKGROUND: Residual neuromuscular block caused by vecuronium alters Pharyngeal function and impairs airway protection. The primary objectives of this investigation were to radiographically evaluate the swallowing act and to record the incidence of and the mechanism behind Pharyngeal dysfunction during partial neuromuscular block. The secondary objective was to evaluate the effect of atracurium on Pharyngeal function. METHODS: Twenty healthy volunteers were studied while awake during liquid-contrast bolus swallowing. The incidence of Pharyngeal dysfunction was studied by fluoroscopy. The initiation of the swallowing process, the Pharyngeal coordination, and the bolus transit time were evaluated. Simultaneous manometry was used to document pressure changes at the tongue base, the Pharyngeal Constrictor muscles, and the upper esophageal sphincter. After control recordings, an intravenous infusion of atracurium was administered to obtain train-of-four ratios (T4/T1) of 0.60, 0.70, and 0.80, followed by recovery to a train-of-four ratio of more than 0.90. RESULTS: The incidence of Pharyngeal dysfunction was 6% during the control recordings and increased (P < 0.05) to 28%, 17%, and 20% at train-of-four ratios 0.60, 0.70, and 0.80, respectively. After recovery to a train-of-four ratio of more than 0.90, the incidence was 13%. Pharyngeal dysfunction occurred in 74 of 444 swallows, the majority (80%) resulting in laryngeal penetration. The initiation of the swallowing reflex was impaired during partial paralysis (P = 0.0081). The Pharyngeal coordination was impaired at train-of-four ratios of 0.60 and 0.70 (P < 0.01). A marked reduction in the upper esophageal sphincter resting tone was found, as well as a reduced contraction force in the Pharyngeal Constrictor muscles. The bolus transit time did not change significantly. CONCLUSION: Partial neuromuscular paralysis caused by atracurium is associated with a four- to fivefold increase in the incidence of misdirected swallowing. The mechanism behind the Pharyngeal dysfunction is a delayed initiation of the swallowing reflex, impaired Pharyngeal muscle function, and impaired coordination. The majority of misdirected swallows resulted in penetration of bolus to the larynx. (Less)
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functional assessment of the pharynx at rest and during swallowing in partially paralyzed humans simultaneous videomanometry and mechanomyography of awake human volunteers
Anesthesiology, 1997Co-Authors: Lars I Eriksson, Olle Ekberg, Eva Sundman, Rolf Olsson, Lena Nilsson, Hanne Witt, Richard KuylenstiernaAbstract:BACKGROUND: Functional characteristics of the pharynx and upper esophagus, including aspiration episodes, were investigated in 14 awake volunteers during various levels of partial neuromuscular block. Pharyngeal function was evaluated using videoradiography and computerized Pharyngeal manometry during contrast bolus swallowing. METHODS: Measurements of Pharyngeal Constrictor muscle function (contraction amplitude, duration, and slope), upper esophageal sphincter muscle resting tone, muscle coordination, bolus transit time, and aspiration under fluoroscopic control (laryngeal or tracheal penetration) were made before (control measurements) and during a vecuronium-induced partial neuromuscular paralysis, at fixed intervals of mechanical adductor pollicis muscle train-of-four (TOF) fade; that is, at TOF ratios of 0.60, 0.70, 0.80, and after recovery to a TOF ratio > 0.90. RESULTS: Six volunteers aspirated (laryngeal penetration) at a TOF ratio 0.90 or during control recording. Pharyngeal Constrictor muscle function was not affected at any level of paralysis. The upper esophageal sphincter resting tone was significantly reduced at TOF ratios of 0.60, 0.70, and 0.80 (P 0.90 is reached. The upper esophageal sphincter muscle is more sensitive to vecuronium than is the Pharyngeal Constrictor muscle.