Changes In Upper Airway Research Articles

An Investigation of Upper Airway Changes Associated With Mandibular Advancement Device Using Sleep Videofluoroscopy in Patients With Obstructive Sleep Apnea

To quantitatively evaluate the effects of the mandibular advancement device (MAD) on changes in the upper respiratory tract during sleep using sleep videofluoroscopy (SVF) in patients with obstructive sleep apnea (OSA). Retrospective analysis. Academic tertiary referral center. Seventy-six patients (68 men and 8 women) who were treated with the MAD for OSA were included from September 1, 2005, through August 31, 2008. All patients underwent nocturnal polysomnography and SVF before and at least 3 months after receipt of the custom-made MAD. Sleep videofluoroscopy was performed before and after sleep induction and was analyzed during 3 states of awakeness, normoxygenation sleep, and desaturation sleep. Changes in the length of the soft palate, retropalatal space, retrolingual space, and angle of mouth opening were evaluated during sleep events with or without the MAD. Without the MAD, the length of the soft palate and the angle of mouth opening increased during sleep events, especially in desaturation sleep, compared with the awake state. The retropalatal space and retrolingual space became much narrower during sleep compared with the awake state. The MAD had marked effects on the length of the soft palate, retropalatal space, retrolingual space, and angle of mouth opening. The retropalatal space and retrolingual space were widened, and the length of the soft palate was decreased. The MAD kept the mouth closed. Sleep videofluoroscopy showed dynamic upper airway changes in patients with OSA, and the MAD exerted multiple effects on the size and configuration of the airway. Sleep videofluoroscopy demonstrated the mechanism of action of the MAD in patients with OSA. The MAD increased the retropalatal and retrolingual spaces and decreased the length of the soft palate and the angle of mouth opening, resulting in improvement of OSA.

Effects of a mandibular advancement device on the upper airway morphology: a cephalometric analysis

The aims of this study were to assess changes in the upper airway morphology associated with an oral appliance in situ in patients suffering from the obstructive sleep apnoea-hypopnoea syndrome and to relate these changes to treatment response. Changes in upper airway morphology as a result of an oral appliance were assessed in 52 patients with obstructive sleep apnoea-hypopnoea syndrome by means of cephalometric analysis. Lateral cephalograms were taken at baseline and after 2-3 months of treatment. Baseline and follow-up cephalograms were traced twice and cephalometric variables were compared. The predictive value of changes in upper airway morphology for the treatment response was evaluated in univariate and multivariate regression analyses. Oral appliance therapy resulted in an increased posterior airway space at the level of the second vertebra, the uvular tip and the base of the tongue. The increase of the posterior airway space at the level of the second vertebra and the uvular tip were the best predictors for relative improvement of the apnoea-hypopnoea index. However, the predictive value for treatment response of these cephalometric upper airway changes should be interpreted with caution.

Dynamic upper airway changes during sleep in patients with obstructive sleep apnea syndrome

Conclusion: The narrowing pattern of the upper airway in obstructive sleep apnea patients may be different in sleep as compared with awake. Three different types of obstruction were observed in these subjects during drug-induced sleep. The different obstruction pattern during drug-induced sleep suggests that different strategies should be selected in upper airway management. Objectives: To identify the sites of narrowing and evaluate dynamic upper airway movement in patients with obstructive sleep apnea syndrome (OSAS) while awake and asleep. Patients and methods: This study included 10 patients treated for OSAS between August 2003 and June 2004. Overnight polysomnography was performed on all patients. Parameters including gender, age, neck circumference, and body mass index were recorded. Ultra-fast MRI during awake and drug-induced sleep was arranged to evaluate the dynamic motion of the upper airway. Results: The narrowing pattern of the upper airway during awake differed from the narrowing pattern during drug-induced sleep in 3 of 10 subjects. Three different types, palatal obstruction, combined upper and lower pharyngeal obstruction, and circumferential obstruction of the upper airway, were observed in these patients during drug-induced sleep.

Dynamic upper airway changes during sleep in patients with obstructive sleep apnea syndrome

Dynamic upper airway changes during sleep in patients with obstructive sleep apnea syndrome

Effect of Body Posture on Pharyngeal Shape and Size in Adults With and Without Obstructive Sleep Apnea

In patients with obstructive sleep apnea (OSA), the severity and frequency of respiratory events is increased in the supine body posture compared with the lateral recumbent posture. The mechanism responsible is not clear but may relate to the effect of posture on upper airway shape and size. This study compared the effect of body posture on upper airway shape and size in individuals with OSA with control subjects matched for age, BMI, and gender. 11 males with OSA and 11 age- and BMI-matched male control subjects. Anatomical optical coherence tomography was used to scan the upper airway of all subjects while awake and breathing quietly, initially when supine, and then in the lateral recumbent posture. A standard head, neck, and tongue position was maintained during scanning. Airway cross-sectional area (CSA) and anteroposterior (A-P) and lateral diameters were obtained in the oropharyngeal and velopharyngeal regions in both postures. A-P to lateral diameter ratios provided an index of regional airway shape. In equivalent postures, the ratio of A-P to lateral diameter in the velopharynx was similar in OSA and control subjects. In both groups, this ratio was significantly less for the supine than for the lateral recumbent posture. CSA was smaller in OSA subjects than in controls but was unaffected by posture. The upper airway changes from a more transversely oriented elliptical shape when supine to a more circular shape when in the lateral recumbent posture but without altering CSA. Increased circularity decreases propensity to tube collapse and may account for the postural dependency of OSA.

Three-dimensional upper-airway changes associated with various amounts of mandibular advancement in awake apnea patients

Mandibular advancement appliances have been used for years in the treatment of obstructive sleep apnea (OSA). However, it has not been completely clarified how the upper airway changes after mandibular advancement. The purpose of this study was to examine the effects of mandibular advancement on anatomic structures of the upper airway in patients with OSA by magnetic resonance imaging. Eleven OSA patients (aged 48.0 +/- 5.86 years) with apnea and hypopnoea index values of 46.8 +/- 21.47 participated in this study. A series of magnetic resonance images was taken for each subject with a custom-made device in the mouth that could advance the mandible by 0, 2, 4, 6, and 8 mm. In addition, an image with the mandible in centric occlusion was taken. Changes in cross-sectional area, sagittal diameter, transverse diameter, and cross-sectional shape in the whole upper airway and the different regions were compared between the various amounts of mandibular advancement. The minimum and mean cross-sectional area of the velopharynx and the mean transverse diameter of the velopharynx increased significantly (P = 0.0001 and P = 0.0016, respectively) during mandibular advancement. However, no statistically significant changes (P > 0.05) in sagittal diameter were found between the various mandibular advancements. In cross-sectional shape, a significant increase (P = 0.0066) was found when the mandible was advanced to 8 mm from 0 mm or centric occlusion position. Mandibular advancement significantly increases the cross-sectional area of the velopharynx in awake OSA patients. This contributes to the increase in its transverse dimension rather than the sagittal, thus resulting in the change of its shape.

The effects of a total laryngectomy on speech breathing

Alaryngeal speech rehabilitation following a total laryngectomy is a multifactorial disorder that includes changes in phonation, respiration, and overall general health. Tracheoesophageal speech is the preferred method of rehabilitation. In this approach, pulmonary air support is diverted from the trachea into the esophagus to generate voicing. Tracheoesophageal speakers must overcome radical upper airway changes, increased resistance in the phonatory source, reduced sensory feedback from the respiratory system, and probable respiratory compromise. This review integrates previous laryngectomy research with recent studies investigating kinematics in tracheoesophageal speakers. Tracheoesophageal speakers are often very intelligible and communicate effectively, but little has been done to investigate the physiological demands of tracheoesophageal speech on speakers. Two recent studies have specifically investigated speech breathing behaviors in tracheoesophageal speakers. Both investigations reported increased effort and differences in speech breathing compared to laryngeal speakers; however, continued research is needed to understand the effects of a total laryngectomy on speech breathing. The physiological changes following a laryngectomy, especially in the ability to produce tracheoesophageal speech, are not well known. Rehabilitation for these individuals requires an understanding of the changes in respiration that might influence speech breathing behaviors.

Pharyngeal narrowing in end-stage renal disease: implications for obstructive sleep apnoea

Sleep apnoea is common in patients with end-stage renal disease (ESRD). It was hypothesised that this is related to a narrower upper airway. Upper airway dimensions in patients with and without ESRD and sleep apnoea were compared, in order to determine whether upper airway changes associated with ESRD could contribute to the development of sleep apnoea. An acoustic reflection technique was used to estimate pharyngeal cross-sectional area. Sleep apnoea was assessed by overnight polysomnography. A total of 44 patients with ESRD receiving conventional haemodialysis and 41 subjects with normal renal function were studied. ESRD and control groups were further categorised by the presence or absence of sleep apnoea (apnoea/hypopnoea index > or =10 events.h(-1)). The pharyngeal area was smaller in patients with ESRD compared with subjects with normal renal function: 3.04 +/- 0.84 versus 3.46 +/- 0.80 cm(2) for the functional residual capacity and 1.99 +/- 0.51 versus 2.14 +/- 0.58 cm(2) for the residual volume. The pharynx is narrower in patients with ESRD than in subjects with normal renal function. In conclusion, since a narrower upper airway predisposes to upper airway occlusion during sleep, it is suggested that this factor contributes to the pathogenesis of sleep apnoea in dialysis-dependent patients.

Upper airway morphologic changes in obstructive sleep apnea hypopnea syndrome patients before and after orthognathic surgery and distraction osteogenesis

To investigate the morphologic changes of upper airway in obstructive sleep apnea and hypopnea syndrome (OSAHS) associated with micrognathism before and after orthognathic surgery and distraction osteogenesis, and subsequently to instruct clinical jobs effectively. Nine OSAHS patients associated with micrognathism (8 males, 1 female, mean age: 28.6 years) received orthognathic surgery and (or) distraction osteogenesis, and the curative effect was evaluated according to the subjective feelings and PSG. Upper airway structure before and after the treatment was measured by Somatom Sensation 16 CT scanner. All 9 patients were clinically cured. The transverse length, the cross section area, and especially the sagittal length of the upper airway were obviously increased after the orthognathic surgery. The changes involved mainly in the velopharyngeal region and the laryngopharyngeal region, but not in the laryngopharyngeal region. The orthognathic surgery and distraction osteogenesis can treat the OSAHS patients with microgonathism effectively by increasing their velopharyngeal and laryngopharyngeal sagittal length of upper airway.

Three-Dimensional Changes in Upper Airways of Patients With Obstructive Sleep Apnea Following Maxillomandibular Advancement

The purpose of this study was to analyze the morphologic changes of the airway in obstructive sleep apnea (OSA) patients by helical computed tomography (CT) scanning following maxillomandibular advancement (MMA) surgery. Twenty consecutive OSA patients treated with MMA from 2000 to 2003 at the University of Alabama at Birmingham Hospital and diagnosed by polysomnography (PSG) were included in this study. The criteria for this study were MMA surgery, pre- and postoperative helical CT scan, and PSG. Lateral (LAT) and anterioposterior (AP) airway dimensions were measured from the level of the hard palate to the hyoid using helical CT scans. There was enlargement of LAT and AP diameters for all patients at all levels. LAT dimensions were enhanced greater than AP in the retroglossal region. MMA results in significant increase in both AP and LAT airway dimensions.

Stimulation of the hypothalamic paraventricular nucleus modulates cardiorespiratory responses via oxytocinergic innervation of neurons in pre-Bötzinger complex

Previously we reported that oxytocin (OT)-containing neurons of the hypothalamic paraventricular nucleus (PVN) project to the pre-Bötzinger complex (pre-BötC) region and phrenic motoneurons innervating the diaphragm (D). The aim of these studies was to determine pathways involved in PVN stimulation-induced changes in upper airway and chest wall pumping muscle activity. In addition, we determined the role of OT-containing neurons in the PVN in mediating increased respiratory output elicited by PVN stimulation. Neuroanatomical experiments, using pseudorabies virus (PRV) as a transneuronal tracer in C8 spinalectomized animals showed that PVN neurons project to hypoglossal motoneurons innervating the genioglossus (GG) muscle. Furthermore, microinjection of the PVN with bicuculline, a GABA(A) receptor antagonist, significantly increased (P < 0.05) peak electromyographic activity of GG (GG(EMG)) and of D(EMG), frequency discharge, and arterial blood pressure (BP) and heart rate. Prior injection of OT antagonist [d-(CH(2))(5),Tyr(Me)(2),Orn(8)]-vasotocin intracisternally or blockade of OT receptors in the pre-BötC region with OT antagonist l-368,899, diminished GG(EMG) and D(EMG) responses and blunted the increase in BP and heart rate to PVN stimulation. These data show that PVN stimulation affects central regulatory mechanisms via the pre-BötC region controlling both respiratory and cardiovascular functions. The parallel changes induced by PVN stimulation were mediated mainly through an OT-OT receptor signaling pathway.

Gene Transcripts of Peripheral Blood as Potential Biomarkers for Allergic Changes in Upper Airways

RATIONALE: Peripheral blood is the most clinically accessible tissue for genomic analyses. Identification of genes which are equally affected by allergic asthma (AA) in peripheral blood mononuclear cells (PBMC) and AA-targeted tissues such as airway brushing cells (ABC) potentially offer a novel noninvasive tool for the prediction of pathological changes in AA-affected airways.

Snoring Imaging: Could Bernoulli Explain It All?

To identify upper airway changes in snoring using CT scanning, to clarify the snoring mechanism, and to identify the key structures involved. Forty patients underwent CT examination of the head and neck region according to snoring habits; patients were classified into non-snoring (n = 14), moderately loud snoring (n = 13), and loud snoring (n = 13) groups. Comparative analysis. Using CT images, areas, the anteroposterior and transversal distances of the pharyngeal space at different levels, and the thickness and length of the soft palate and uvula and their angle against the hard palate were measured; evidence of impaired nasal passages was noted; the extent of pharyngeal inspiratory narrowing was the ratio between the area at the hard palate level and most narrow area; and expiratory narrowing was the ratio between the area behind the root of the tongue and the most narrow area. Greater pharyngeal inspiratory narrowing (p = 0.0015) proportional to the loudness of snoring (p = 0.0016), and a longer soft palate with uvula (p = 0.0173) were significant for snoring. Impaired nasal breathing was significantly related (p = 0.029) only to the loud snoring group. The body mass index and age of snoring persons were also significantly higher. Snoring is associated with typical changes that can be revealed by CT scanning. Greater pharyngeal narrowing is the most important factor. Given the "Venturi tube" shape of the pharynx, the Bernoulli pressure principle plays a major role in snoring. The key structure in snoring is the soft palate: it defines the constriction and is sucked into vibrating by negative pressure that develops at this site. Its repetitive closures present an obstruction to breathing, producing the snoring sound, and should therefore be the target for causal treatment of snoring. Obstacles in the upper airway that increase negative inspiratory pressure could not be confirmed as important for the development of snoring, although they may increase its loudness.

Effects of chronic intermittent asphyxia on haematocrit, pulmonary arterial pressure and skeletal muscle structure in rats.

Sleep-disordered breathing in humans is a common condition associated with serious cardiovascular and other abnormalities. The prevalence and pathogenesis of increased haematocrit and pulmonary hypertension is controversial and it has been suggested that these changes only occur in patients who also have daytime continuous hypoxaemia. The hypothesis tested here is that the chronic intermittent hypoxia and asphyxia associated with sleep-disordered breathing causes erythropoiesis and pulmonary hypertension and that this occurs in the absence of periods of continuous hypoxia. In humans and animals with obstructive sleep apnoea, there are abnormalities of upper airway muscle structure that have been ascribed to increased load placed on these muscles. An alternative hypothesis is that chronic intermittent hypoxia and asphyxia cause changes in upper airway muscle structure and function. To test these hypotheses, rats were exposed to intermittent hypoxia and asphyxia for 8 h per day for 5 weeks. This caused an increase in haematocrit, right ventricular weight and pulmonary arterial pressure. There were only slight changes in diaphragm, upper airway and limb muscle structure and force production but in general, muscle fatigability was increased. In conclusion chronic intermittent hypoxia and asphyxia cause an increase in haematocrit and pulmonary arterial pressure in the absence of periods of continuous hypoxia. Chronic intermittent hypoxia and asphyxia have little effect on skeletal muscle structure and force production but increase muscle fatigue. Increased upper airway muscle fatigue could lead to a vicious cycle of further compromise in upper airway patency and further hypoxia and asphyxia.

Discussion

The authors provided an excellent article and contribution to the literature that focuses our attention on the pharyngeal airway. In obstructive sleep apnea (OSA), the critical area of research is the “hole of the donut.” The authors evaluated the upper airway changes after maxillomandibular advancement (MMA) surgery for OSA. The interesting aspect is the use of subjective fiberoptic nasopharyngoscopy with an inspiratory force meter to consistently measure patient effort (negative pressure). The results confirm my clinical experience and research that MMA improves the lateral and anteroposterior dimension. I once thought that straight advancement of the tongue base might actually narrow the lateral dimension by creating an elipse.

Sleep-related changes in the human ‘neuromuscular’ ventilatory response to hypoxia

The ventilatory responses to hypercapnia and hypoxia are reduced during sleep compared to wakefulness. However, sleep-related increases in upper airways’ resistance could reduce these ventilatory responses independently of any change in the neural output to the respiratory pump muscles. It is therefore possible that respiratory chemosensitivity, per se, is unchanged by sleep. To investigate this, four healthy male subjects were mechanically ventilated to abolish spontaneous respiratory muscle activity. The response to transient isocapnic hypoxia was quantified from the magnitude of the electromyographic activity induced in the diaphragm and from the associated reduction in peak inspiratory pressure; these indicies of respiratory motor output will not be affected by any sleep-related changes in upper airways’ resistance. In all individuals, the responses to hypoxia were markedly attenuated during sleep compared to wakefulness. These observations, assessing the ‘neuromuscular’ ventilatory response, are consistent with a sleep-related reduction in respiratory chemosensitivity that is independent of any changes that may be due to increases in upper airways’ resistance.

Upper Airway Changes in Snorers and Mild Sleep Apnea Sufferers After Uvulopalatopharyngoplasty (UPPP)

We used upper airway (UA) imaging in 20 patients to determine (1) whether an effective enlargement of the UA is obtained after uvulopalatopharyngoplasty (UPPP), and (2) whether UA modifications explain the results of such surgery. Cephalometric measurements were made to assess the posterior airway space, the length and width of the soft palate, and the distance between the hyoid bone and the mandibular plane. Pharyngeal CT measured the airway cross-sectional area (CSA) at each 10-mm slice from 10 mm above (-10) to 40 mm below (+40) the hard palate. Polysomnography was performed before and after surgery (10+/-10 [SD] months). Good responders were defined by an apnea-hypopnea index (AHI) of <10 postsurgery or, in patients in whom AHI was initially <10, a reduction of AHI >50% of the initial AHI. Twenty patients (age=45+/-11 years) were studied. For the whole group, the mean body mass index (26+/-4 kg/m2) and AHI (14+/-13 vs 18+/-16/h) were unchanged after UPPP. The results of the surgery were mediocre with 7 good responders (35%) and 13 nonresponders (65%) defined by polysomnographic criteria. The only changes on UA imaging for the group as a whole after UPPP were decrease in length (40+/-6 vs 29+/-5 mm, p< or =0.0006) and increase in width of the soft palate (11.5+/-2.7 vs 13.6+/-3.5 mm, p< or =0.006). The increase or decrease in minimal CSA at the oropharyngeal (OP) level after UPPP was significantly correlated with the change in AHI (r=-0.54, p<0.02). Moreover, the changes in CSA obtained at the OP level were significant only in the patients who responded favorably to UPPP (7 vs 13 nonresponders). Postoperative OP enlargement is associated with a good outcome of UPPP. Persistent narrowing in nonresponders could be due to the increase in soft palate width after surgery.

Relationship between difficult tracheal intubation and obstructive sleep apnoea

The upper airway abnormalities predisposing to difficult tracheal intubation may also predispose to obstructive sleep apnoea (OSA). The potential association is important as both conditions increase perioperative risk and patients with a trachea that is difficult to intubate may need assessment for OSA. We determined if patients with difficult intubation are at greater risk of OSA and, if so, whether or not they have characteristic clinical or radiographic upper airway changes. We studied 15 patients in whom the trachea was difficult to intubate and 15 control patients. Each was evaluated clinically (Mallampati score, thyromental distance, neck circumference, head extension), polysomnographically (apnoea-hypoponea index (AHI)) and radiographically (lateral cephalometry). AHI was greater in the difficult intubation group (mean 28.4 (SD 31.7)) compared with controls (5.9 (8.9)) (P < 0.02); eight of 15 patients in the difficult intubation group and two of 15 in the control group had an AHI > 10 (P < 0.03). Difficult intubation, but not OSA, was associated (P < 0.05) with a smaller thyromental distance and mandibular length, and greater soft palate length. Both difficult intubation and OSA were associated (P < 0.05) with a greater Mallampati score, anterior mandibular depth, and smaller mandibular and cervical angles. OSA, but not difficult intubation, was associated (P < 0.05) with increased neck circumference, tongue area and craniocervical angle, and decreased head extension, mandibular ramus length and atlantooccipital distance. We conclude that difficult intubation and OSA are related significantly. They share anatomical features which act to reduce the skeletal confines of the tongue. Patients with OSA may compensate, when awake, by increasing craniocervical angulation, which increases the space between the mandible and cervical spine and elongates the tongue and soft tissues of the neck.

A method to evaluate upper airway mechanics following intervention in snorers

Purpose: To describe a method that measures multisegment upper airway changes following intervention for snoring and obstructive apnea that controls for physiological fluctuations during sleep. Patients and Methods: Retropalatal, retroglossal, and retrohyoid airway segments were evaluated before and after application of an oral appliance (OA) in four snoring subjects. Twelve airway segments were evaluated. Physiological fluctuations during sleep were controlled with variably applied nasal continuous positive applied pressure (CPAP), benzodiazepam-induced sleep, and obtaining measures at zero flow on the first test breath. Airway area was measured endoscopically. Results: The methodology identified that following intervention with an OA, maximum retroglossal airway size increased 23.3% ± 7.5% ( P < .05) and retrohyoid size decreased −63.5% ± 16.0% ( P < .05). No changes in retropalatal area (−2.5% ± 3.0%) or closing pressure were observed. The level of primary obstruction shifted inferiorly in one patient. Airway measures prior to intervention showed small alterations of applied pressure (1 cm H 2O) changed retropalatal and retroglossal area an average of 10% ± 0.9%/cm H 2O. Conclusion: The mechanical effects of limited airway intervention can be measured with a hypotonic, pressure-controlled methodology. At small airway areas, the airway is highly collapsible and airway size fluctuates. Small changes in applied or physiological forces may alter the airway as significantly as the effects of the intervention being evaluated. The hypotonic upper airway method provides a method to control airway collapse and evaluate interventions, such as OA or surgery, for snoring and obstructive sleep apnea syndrome.

A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea.

The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post-palatal and post-lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post-palatal and post-lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post-palatal and post-lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.