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Query: UMLS:C0344329 (collapse)
 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated whether or not the adaptation of peripheral chemoreceptor (PCR) activity can contribute to hypoxic ventilatory depression (HVD) during sustained hypoxia for 20 min in both healthy subjects and patients with sleep apnea. Effects of HVD on diaphragm (DIA) and genioglossal muscle (GG) were also assessed. Withdrawal test, which is well established to solely represent the function of PCR, was repeatedly conducted at 5 and 20 min during sustained hypoxic condition. The results suggested that PCR did not play an important role in the development of HVD. When HVD ensued during sustained hypoxia, minute ventilation and EMGDIA were suppressed to the same extent in both groups. On the other hand, EMGGG was strongly and consistently attenuated in OSAS, whereas it was not always the case in healthy subjects. We speculate that treatment for hypoxic conditions can induce improvement of impaired regulation of breathing via central mechanisms, and it can be an important factor reducing the incidence and the severity of upper airway occlusion or collapse.
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PMID:[Hypoxic ventilatory response and hypoxic depression]. 130 12

The importance of nasal airflow resistance in the pathogenesis of obstructive sleep apnea syndrome (OSAS) remains contentious. We performed formal nocturnal polysomnography (PSG) on OSAS patients under conditions of baseline and reduced nasal resistance to answer two main questions. First, to what degree does baseline nasal airflow resistance influence upper airway collapse in OSAS patients? Second, in what proportion of the OSAS population is baseline nasal resistance contributing to the pathogenesis of upper airway collapse? Our study group consisted of 10 patients with a wide range of OSAS severity. Six of these patients had symptoms and clinical evidence of chronic nasal obstruction which, in some, was associated with markedly elevated nasal resistance. A placebo (normal saline) was instilled in the nose of each patient on the night of baseline data collection. On the treatment night of the study, nasal resistance was reduced by application of topical vasoconstrictor and insertion of vestibular stents designed to dilate the area of the nasal valve. Posterior rhinomanometry was used to measure resistance to nasal airflow immediately before and after each PSG study. Although treatment was associated with a subjective improvement in sleep quality and mean drop in nasal resistance of 73% (P less than 0.001), there was no significant improvement in sleep architecture, nocturnal oxygenation, or the amount of apnea experienced by patients. The most significant improvement was a reduced number of arousals/hour from 52.4 +/- 12.4 on placebo to 43.7 +/- 10.2 on treatment (P less than 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The importance of nasal resistance in obstructive sleep apnea syndrome. 140 70

Upper airway (UA) collapse in obstructive sleep apnea (OSA) is considered in part to result from the decrease in UA dilator muscle tone that occurs during sleep. We hypothesized that augmentation of UA muscle function by transcutaneous electrical stimulation (TES) might function to enlarge UA size during wakefulness and/or prevent UA collapse during sleep in patients with OSA. Eight male patients with OSA were studied both awake and asleep, with TES administered to the submental region in two patients and to both the submental and subhyoid regions in six patients. Fast-CT scans obtained at FRC and end-inspiration (VTei) demonstrated increased UA size with tidal breathing, p less than or equal to 0.05. The active generation of -10 cm H2O pressure at FRC substantially decreased UA size, p less than or equal to 0.001. However, no changes in UA size were detected at either FRC or VTei with TES applied at 50 and 100% of the maximal tolerated intensity. The collapsibility of the UA in response to the generation of -10 cm H2O pressure was also unchanged by TES. In contrast to the lack of effect of TES on UA size, voluntary protrusion of the tongue increased cross-sectional area (CSA) of the orohypopharyngeal (OHP) segment of the UA, p less than 0.05, and to a lesser extent the CSA of the distal velopharyngeal segment, p = 0.06. When applied during sleep, TES failed to prevent or improve either sleep-disordered breathing or sleep architecture.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The effects of transcutaneous electrical stimulation during wakefulness and sleep in patients with obstructive sleep apnea. 141 92

The cause of failure after uvulopalatopharyngoplasty (UPPP) in idiopathic obstructive sleep apnea (OSA) is poorly understood, but has been speculated to be due, in part, to persistent collapse in the lower oropharynx. In order to determine the specific level of upper airway obstruction during sleep, a multisensor pressure catheter has been developed with five solid-state ultraminiature sensors. Four sensors in the pharynx simultaneously measure multiple pressure levels, with no need to move the catheter during sleep. One distal esophageal port measures the respiratory effort. To evaluate the use of this catheter, manometry in twelve patients was reviewed and compared the use of this catheter, manometry in twelve patients was reviewed and compared to simultaneous videoendoscopy. The initial site of obstruction was the palate in nine patients (75%) and the tongue base in three (25%). Three patients with initial obstruction at the palate manometrically demonstrated distal obstruction on subsequent occluded breaths. Furthermore, simultaneous videoendoscopy in four patients with a palatal level of obstruction also identified marked near-total visual collapse without obstruction of the lower oropharynx that was not identified by pharyngeal manometry. The endoscopy revealed that at the initial site of obstruction, collapse appeared to have occurred passively during expiration and not on inspiration. Inferior to the site of manometric obstruction, collapse occurred during inspiration associated with increased negative inspiratory pressures. These results demonstrate that a multisensor pressure catheter can objectively identify the level of obstruction during sleep.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A multisensor solid-state pressure manometer to identify the level of collapse in obstructive sleep apnea. 143 3

Sleep apnea syndrome (SAS) results from modification in the control of respiration and of upper airway caliber during sleep. Although there is some overlap between central (CSAS) and obstructive (OSAS) sleep apnea syndromes, each syndrome has specific pathological associations. The first part of this review concerns the pathophysiology of OSAS, including periodic breathing and upper airway collapse. In the second part, each specific etiology is examined, and the respective contribution of anatomic narrowing and neuromuscular dysfunction of the upper airway is mentioned. Our experience with about 375 patients with sleep-related breathing disorders is also reported, with regard to the specific etiologies of CSAS and OSAS.
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PMID:Sleep apnea syndromes (SAS) of specific etiology: review and incidence from a sleep laboratory. 147 Aug 4

Because uvulopalatopharyngoplasty (UPPP) as the sole procedure for severe obstructive sleep apnea syndrome (OSAS) is often inadequate, multiple other procedures have been developed. These have been directed at other sites of potential collapse of the upper airway. Initial experience with midline glossectomy (MLG) has shown direct modification of the tongue base to be an effective procedure in a subset of patients with OSAS. Lingualplasty, a modification of MLG, is demonstrated to provide an improved response rate. Twenty-two consecutive patients with severe OSAS and Fujita type II airway classification (retropalatal, oropharyngeal, and hypopharyngeal compromise) underwent lingualplasty. Fourteen patients had previously undergone unsuccessful UPPP. Eight had synchronous lingualplasty and UPPP. All were selected for lingualplasty because of obstructive tongue base anatomy. Responders were defined as having a respiratory disturbance index (RDI) of less than 20 events/hour. For the entire group, 17 of 22 (77%) were classified as responders, with RDI decreasing from 58.8 +/- 39.5 events/hour to 8.1 +/- 6.2 events/hour. Lingualplasty, as an isolated procedure, resulted in a 79% responder rate, with RDI decreasing from 50.2 events/hour to 8.6 events/hour. There were no significant changes in the RDI of the nonresponder groups. No differences were identified that discriminated responders from nonresponders, including age, body mass index, or cephalometry. There were six complications (27%), including bleeding (3), tongue edema (1), prolonged odynophagia (1), and subcutaneous emphysema related to tracheotomy (1). All resolved with treatment. These results indicate that in appropriately selected patients who do not respond to UPPP, lingualplasty is a significant improvement over MLG.
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PMID:Clinical experience with lingualplasty as part of the treatment of severe obstructive sleep apnea. 152 1

Obstructive sleep apnoea syndrome (OSAS) is a frequent and severe condition due to repeated obstruction of the upper airways during sleep. Sixty-five patients (57 men, 8 women) with clinical sleep apnoea syndrome were explored by pharyngeal endoscopy during wakefulness and during sleep induced by propofol, this anaesthetic agent enabling the patient to retain automatic respiratory movements. Nocturnal polygraphy was positive (apnoea-hypopnoea index greater than 10) in 60 patients (53 men, 7 women) and negative (less than 10) in 5 patients. The terms narrowing and obstruction were defined from our description of the pharyngeal cavity as seen at endoscopy. Endoscopic exploration during wakefulness displayed 4 pharyngeal lesions (2 cancers and 2 benign tumours) which were not responsible for the patients' OSAS. Forty-eight patients had narrowing of the pharynx (oropharynx in 45, nasopharynx in 3). Endoscopic exploration during sleep revealed inspiratory obstruction of the pharynx in 43 patients and inspiratory bronchial collapse in 1 patient. This study shows that the endoscopic findings can predict the efficacy of continuous positive pressure respiration in 97.3 percent of patients with obstruction of the oro and hypopharynx. The efficacy of uvulo-palato-pharyngoplasty in patients with obstructed oropharynx is questioned. The value of maxillary and/or mandibular surgical protrusion is discussed.
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PMID:[Pharyngeal and bronchial endoscopic study in the diagnosis and treatment of sleep apnea syndrome]. 153 38

Pharyngeal collapse in obstructive sleep apnea patients is likely a product of a sleep-related decrement in pharyngeal dilator muscle activity superimposed upon abnormal airway anatomy. We postulate that during wakefulness, increased pharyngeal dilator muscle activity in apnea patients compensates for diminished airway size thus maintaining patency. We studied the waking genioglossus (GG) electromyogram (EMG) activity in 11 OSA patients and 14 age-matched controls to determine if GG activity is higher in the awake state in apnea patients than controls. To make this determination, we developed a reproducible methodology whereby true maximal GG EMG could be defined and thus basal activity quantitated as a percentage of this maximal value. Therefore, direct comparisons of basal activity between individuals was possible. We observed apnea patients to have significantly greater basal genioglossal activity compared to controls (40.6 +/- 5.6% vs. 12.7 +/- 1.7% of maximum). This difference persisted when size-matched subsets were compared. This augmented GG activity in apnea patients could be reduced with positive airway pressure. We speculate that this neuromuscular compensation present during wakefulness in apnea patients may be lost during sleep leading to airway collapse.
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PMID:Waking genioglossal electromyogram in sleep apnea patients versus normal controls (a neuromuscular compensatory mechanism). 156 96

This article has reviewed the anatomic, compliance, reflex, and respiratory muscle variables that affect upper airway caliber and abnormalities which may precipitate upper airway collapse during sleep. One or more of these variables may be important in the mechanism of OSA in any given patient. First, anyone with anatomic narrowing of the upper airway is susceptible to OSA. However, we do know if anatomic narrowing of the upper airway is necessary for the development of OSA. Surely, heavy snoring produces pharyngeal trauma and possibly edema or inflammation, which in turn may narrow the upper airway. Submucosal adipose tissue or cervical adipose tissue may compress the airway when the tonic electrical activity of the pharyngeal muscles decreases with sleep onset. Data reviewed support the idea that the upper airway of OSA patients may be more collapsible than the upper airway of nonapneic subjects. Intrinsic tissue abnormalities have not been demonstrated that might be responsible for this collapsibility. Changes in collapsibility found are consistent with, and may be due to, changes in tonic and phasic contraction of upper airway muscles. Abnormalities in reflexes affecting upper airway size surely might exist in OSA. Edema or inflammation of pharyngeal tissues might not only narrow the upper airway but might also impair normal function of the receptors responsible for initiating protective reflexes. We propose the fluctuation between a low- and a high-drive state contributes to upper airway collapse in OSA. With this fluctuation the balance of forces and critical pressure concepts discussed above come into play (Fig 6). By stimulating upper airway inspiratory muscles, CO2 eliminates the hypoapneic, low-drive, high-resistance periods and thereby reduces the number of apneas. In addition, preferential stimulation of upper airway muscle activity dilates the upper airway per se. If the relative value of each of these factors can be determined diagnostically, perhaps therapy can be made more specific. By being more specific, therapy should be more successful than the present practice of prescribing a particular therapy, regardless of the specific mechanism responsible for the OSA in a given patient.
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PMID:Mechanisms of obstructive sleep apnea. 820 24

The frequency of obstructive sleep apnea syndromes in children is not negligible. The diagnosis is based on the parents' answers and on sleep recordings. Radiographs sometimes help defining the site of obstruction. However, except when there is a considerable, clinically obvious tonsillar hypertrophy (which is fortunately the most frequent case), the exact location of the obstruction may be difficult to assess. In fact, it is far less obvious and more often multiple than in adults, especially in cases of craniofacial malformation. A pharyngolaryngeal exploration technique with a flexible endoscope under general anesthesia (GA) has been developed in our department. With natural ventilation, when a GA is induced with halothane through a mask, muscular relaxation similar to that of natural sleep is obtained. A thin flexible endoscope is then inserted through the mask to observe the obstructive structures at the nasal, rhino/oropharyngeal or pharyngolaryngeal levels. During the past two years, 17 children were examined with this technique, which allows an extremely accurate diagnosis of the site of the obstruction. Four children had a craniofacial malformation. The examination evidenced 9 cases of adenotonsillar hypertrophy, 4 cases of dynamic laryngeal obstruction, 3 cases of basilingual obstruction and one case of circular collapse of the oropharynx. The evolution under treatment confirm the merits of this endoscopic examination technique for the etiological diagnosis of respiratory obstruction.
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PMID:[Pharyngolaryngeal fibroscopy under general anesthesia in children. Technique and indications in sleep apnea and hypopnea]. 178 7


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