PubMed Health⌕ Search

Biomedical subjects

A A Lowe

Publications and source records attributed to A A Lowe.

At least 19 recordsLinked to original sources
PubMed2001

Effects of a titratable oral appliance on supine airway size in awake non-apneic individuals.

STUDY OBJECTIVES: To define morphological changes in the upper airway and its surrounding structures after the insertion of a titratable mandibular repositioner. DESIGN: Ten non-apneic adult males participated in this study. A set of supine lateral cephalograms was taken for each subject at the end of expiration with a titratable oral appliance in place in four mandibular positions: most retruded (RP), maximum protrusion (MAX), 33% of MAX (MAX33), and 67% of MAX (MAX67). Changes in the anteroposterior width of the upper airway, positions of the hyoid bone and the third cervical vertebra were compared between the four mandibular positions. An ANOVA was used to test for statistical significance. SETTING: N/A. PATIENTS OR PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The anteroposterior width of the velopharynx significantly increased when the mandible was advanced from RP to MAX67 and MAX. However, there were no significant changes in the anteroposterior width of the oropharynx. Significant forward displacement of the hyoid bone and third cervical vertebra together with the mandible was found in MAX67 and MAX compared to RP. CONCLUSION: Especially in MAX67 and MAX, the titratable oral appliance significantly enlarges upper airway size in the velopharynx and results in a forward displacement of the hyoid bone and the third cervical vertebra.

Adult↗
PubMed2000

Treatment, airway and compliance effects of a titratable oral appliance.

STUDY OBJECTIVES: To measure the effects of a titratable anterior mandibular repositioner on airway size and Obstructive Sleep Apnea (OSA) and to evaluate its compliance. DESIGN: Before and after insertion sleep studies were obtained in a total of 38 OSA patients of varying severity from three different sites. Covert compliance was measured by means of a newly-developed, miniaturized, temperature-sensitive, imbedded monitor. Validity testing was completed in six adult volunteers who wore monitors imbedded into small acrylic appliances. MEASUREMENTS AND RESULTS: The mean RDI before treatment was 32.6 (SEM 2.1) and after the insertion of the appliance, the RDI was reduced to 12.1 (SEM 1.7, p<0.001). RDI was reduced to less than 15/hour in 80% of a group of moderate OSA patients (RDI 15 to 30) and in 61% of a group of severe OSA patients (RDI > 30) with respect to baseline RDI. Fiber optic video endoscopy was performed on 9 OSA patients with and without the appliance. No significant differences in hypopharynx or oropharynx cross sectional areas were found, but at the level of the velopharynx, the airway size was significantly increased (p<0.05). The index of agreement was 0.99 between the monitor clock time and the subject's log sheets. Compliance data from eight OSA subjects instructed to wear the appliance during sleep indicated that it was worn for a mean of 6.8 hours with a range of 5.6 to 7.5 hours per night. CONCLUSION: The titratable adjustable mandibular advancement appliance, made from thermoelastic acrylic, significantly reduces RDI in moderate to severe OSA patients, has a direct effect on airway size and is well worn throughout the night.

Adult↗
PubMed2000

Sleep bruxism in patients with sleep-disordered breathing.

The aim was to test the hypothesis of a direct association between sleep-disordered breathing and sleep bruxism. The frequency of masseter contraction (MC) episodes and rhythmic jaw movements (RJM) was measured in patients with mild and moderate obstructive sleep apnoea (OSA). The diagnosis of sleep bruxism was made from a combination of questionnaire, clinical observation and all-night polysomnographic recording which included masseter electromyography. A total of 21 patients (19 males/two females, mean age 40.0 years+/-9.2 SD) were randomly selected from a provisional diagnosis of snoring and OSA by a sleep physician. In the patients with mild OSA [n=11, mean apnoea hypopnoea index (AHI)=8.0+/-4.1 SD, body mass index (BMI)=29.1+/-5.0], the diagnosis of sleep bruxism was made in six out of 11 patients (54%); similarly, four out of 10 patients (40%) with moderate OSA (n=10, mean AHI=34.7+/-19.1, BMI=30.6+/-5.0) were identified as bruxists. Although the combination of clinical, subjective estimation and nocturnal electromyographic recording of masseter muscle might provide a more solid base for the diagnosis of sleep bruxism, the result is biased by the variation in the bruxing activity. MC episodes were associated with the termination of apnoea or hypopnoea episodes in only 3.5% of the mild group and 14.4% of the moderate group (p<0.05). It appears that sleep bruxism is rarely directly associated with apnoeic events, but is rather related to the disturbed sleep of OSA patients.

Adult↗
PubMed2000

Cephalometric comparisons between Chinese and Caucasian patients with obstructive sleep apnea.

The purpose of this study was to compare two groups of adult men from different ethnic backgrounds and with obstructive sleep apnea; they were selected by matching age, gender, skeletal pattern, body mass index, and respiratory disturbance index. Pretreatment cephalometric radiographs and overnight polysomnograms of 30 Chinese and 43 Caucasian patients with Class II, Division 1 malocclusions were analyzed to investigate if there were craniofacial and upper airway structural differences between the two ethnic groups. The Chinese group, when compared with the group of Caucasian patients, revealed more severe underlying craniofacial skeletal discrepancies with significantly smaller maxilla and mandibles, more severe mandibular retrognathism, proclined lower incisors, increased total and upper facial heights, and steeper and shorter anterior cranial bases. However, no significant differences were found between the two groups in posterior facial height, ratio of upper to lower anterior facial height, and the position of hyoid bone, maxilla, and upper incisors. With regard to soft tissue and upper airway measurements, there were no significant ethnic differences in tongue and soft palate size, vertical length of oropharynx, and anteroposterior dimensions of the upper airway at most of the levels except for a larger super-posterior airway space, a larger nasopharynx and oropharynx cross-sectional area, and a smaller tongue height in the Chinese group. We conclude that there are a number of craniofacial and upper airway structures that differ between the two ethnic groups that may be relevant to the treatment of obstructive sleep apnea in various ethnic groups.

Asian People↗
PubMed2000

Effects of a mandibular repositioner on obstructive sleep apnea.

The purpose of this study was to investigate the effects of a mandibular repositioner on airway, sleep, and respiratory variables in patients with obstructive sleep apnea. Twenty-two patients selected for this study were confirmed with a diagnosis of obstructive sleep apnea based on initial nocturnal polysomnography. The patients were fitted with a mandibular repositioner designed to hold the mandible anteroinferiorly. Six months later, an outcome polysomnographic study was undertaken for each patient with the appliance in place. Lateral cephalometric radiographs in the upright position were also obtained before and after 6 months of treatment. The respiratory disturbance index decreased in 21 of the 22 patients with the appliance in place. The mean respiratory disturbance index of the 22 patients decreased significantly from 40.3 to 11.7 events per hour (P <.01). Some 59.1% of subjects were considered a treatment success with follow-up respiratory disturbance index < 10 events per hour. The mean minimum blood oxygen saturation level during sleep also improved significantly from 73.4% to 81.3% (P <. 01). The mandibular repositioner was constructed to position the mandible at 75% of the maximal mandibular advancement and with a 7 mm opening between the upper and lower incisors, and no aberrant effect on temporomandibular joint was noted. The retropalatal airway space increased and the cross-sectional area of the soft palate and the vertical distance of the hyoid bone to the mandibular plane decreased significantly. The tongue posture became significantly flatter. A significant linear correlation was found between the reduction in apnea index and specific craniofacial skeletal structures (length of anterior cranial base, mandibular plane angle, and upper to lower facial height ratios, P <.05). Subjects with a smaller reduction in apnea index tended to have shorter anterior cranial bases, steeper mandibular planes, and smaller upper to lower facial height ratios. We conclude that a mandibular repositioner may be an effective treatment alternative for obstructive sleep apnea and that a reduction in the frequency of apneic episodes is mainly attributed to the effects of the appliance on oropharyngeal structures.

Adult↗
PubMed2000

Factors related to the efficacy of an adjustable oral appliance for the treatment of obstructive sleep apnea.

AIM: The purpose of this study was to investigate whether any physiological or cephalometric parameters could be used to predict the efficacy of the Klearway oral appliance (OA) for the treatment of obstructive sleep apnea (OSA). METHODS: Forty-two male and 5 female patients with OSA were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) > 15 per hour. Repeat polysomnography was performed with the appliance in place. Baseline cephalometry was performed for each patient. Subjects were divided into 3 groups on the basis of the degree of change in AHI with OA therapy: good response (> 75% decrease in AHI), moderate response (25% to 75% decrease range in AHI), and poor response (< 25% decrease in AHI). RESULTS: Patients with a good response were younger and had smaller upper airways. A stepwise regression analysis revealed that a better treatment response with the Klearway appliance was obtained in patients who were younger and had a lower body mass index, a longer maxilla, a smaller oropharynx, a smaller overjet, less erupted maxillary molars, and larger ratio of vertical airway length to the cross-sectional area of the soft palate.

Adult↗
PubMed1999

Mandibular posture during sleep in patients with obstructive sleep apnoea.

Vertical mandibular posture is thought to be related to narrowing of the upper airway, because mouth opening is associated with an inferior-posterior movement of the mandible and the tongue which influences pharyngeal airway patency. To test whether the mandibular posture is related to the occurrence and/or termination of obstructive sleep apnoea (OSA), the vertical mandibular position was recorded intraorally using a magnet sensor during a standard sleep study in seven patients with OSA. Measurements were recorded during sleep both in the supine and lateral recumbent positions. The percentage of total sleep time spent with mandibular opening greater than 5 mm was significantly larger (p<0.001) in patients with OSA (69.3+/-23.3%) compared with our previous results obtained from healthy adults without OSA (11.1+/-11.6%). The stage of sleep affected the vertical mandibular posture during sleep in the supine position, but not in the lateral recumbent position in patients with OSA. In non-rapid eye-movement sleep, mandibular opening increased progressively during apnoeic episodes and decreased at the termination of apnoeic episodes. In contrast, no significant change in mandibular posture occurred in apnoeic episodes during rapid eye-movement sleep. It was concluded that the vertical mandibular posture is more open during sleep in patients with OSA than in healthy adults and that mandibular opening increases progressively during apnoeic episodes and decreases at the termination of those episodes.

Analysis of Variance↗
PubMed1999

Tongue shape in obstructive sleep apnea patients.

Clinicians have long suspected that tongue shape differs between obstructive sleep apnea (OSA) patients and normal subjects. The purpose of this study was to determine whether such differences exist. Because of the difficulty in specifying reproducible homologous landmarks for the tongue, a morphometric technique-the eigenshape analysis-was used. The eigenshape analysis transforms an outline contour into a set of discrete numbers that are tangent angles of the curvature along the outline at each digitized point on the outline. Pairs of cephalograms were taken of 80 male patients in upright and supine positions. The subjects were subgrouped into four categories according to severity of symptoms. The contour of the tongue was traced, digitized, and subgrouped. When the major portion of the tongue shape variations in the supine position were graphically compared between subgroups, variations in the nonapneic group were distinguished from those in the apneic groups. The results suggest that the eigenshape analysis on cephalograms in the supine position may be a useful tool to distinguish OSA subjects from nonapneic subjects.

Adult↗
PubMed1999

Shape of the face and tongue in obstructive sleep apnea patients--statistical analysis of coordinate data.

OBJECTIVES: To determine the shape difference of the face and tongue of obstructive sleep apnea (OSA) patients, in comparison to those of non-apneic patients. DESIGN: Retrospective analysis of observational data on a cohort of patients. SETTING: A university teaching hospital and sleep referral center. SAMPLE POPULATION AND METHOD: Eighty patients referred for overnight polysomnography and lateral cephalometry and who met the selection criteria were included. Upright and supine cephalograms were obtained and subgrouped based on the severity of clinical symptoms. Shape differences between the groups were assessed by a multiple analysis of variance and a Hotelling's T2. MEASUREMENTS AND RESULTS: A set of anatomical landmarks were selected for outlines of the face and the tongue on cephalograms. X and Y coordinates of each landmark were utilized as variables. As symptoms become severe, the hyoid bone and the submental area positioned inferiorly and the fourth vertebra relocated posteriorly with respect to the lower mandibular border. When subjects changed their body position from the upright to the supine, the posterior part of the tongue appeared to sink down. The hyoid bone position to epiglottis-retrognathion line in the supine position distinguishes OSA patients from non-apneic subjects. CONCLUSION: Despite many limitations, we demonstrate that the supine cepahlometrics during wakefulness can be a useful adjunctive diagnostic tool for OSA, when cephalograms are analyzed in a coordinate data form.

Adult↗
PubMed1999

Mandibular advancement oral appliance therapy for obstructive sleep apnoea: effect on awake calibre of the velopharynx.

BACKGROUND: The mechanisms of action of oral appliance therapy in obstructive sleep apnoea are poorly understood. Videoendoscopy of the upper airway was used during wakefulness to examine whether the changes in pharyngeal dimensions produced by a mandibular advancement oral appliance are related to the improvement in the severity of obstructive sleep apnoea. METHODS: Fifteen patients with mild to moderate obstructive sleep apnoea (median (range) apnoea index (AI) 4(0-38)/h, apnoea-hypopnoea index (AHI) 28(9-45)/h) underwent overnight polysomnography and imaging of the upper airway before and after insertion of the oral appliance. Images were obtained in the hypopharynx, oropharynx, and velopharynx at end tidal expiration during quiet nasal breathing in the supine position. The cross sectional area and diameters of the upper airway were measured using image processing software with an intraluminal catheter as a linear calibration. RESULTS: AI decreased to a median (range) value of 0 (0-6)/h (p<0.01) and AHI to 8 (1-28)/h (p<0.001) following insertion of the oral appliance. The median (95% confidence interval) cross sectional area of the upper airway increased by 18% (3 to 35) (p<0.02) in the hypopharynx and by 25% (11 to 69) (p<0.005) in the velopharynx, but not significantly in the oropharynx. Although in general the shape of the pharynx did not change following insertion of the oral appliance, the lateral diameter of the velopharynx increased to a greater extent than the anteroposterior diameter. Following insertion of the oral appliance the reduction in AHI was related to the increase in cross sectional area of the velopharynx (p = 0.01). CONCLUSIONS: A mandibular advancement oral appliance increases the cross sectional area of the upper airway during wakefulness, particularly in the velopharynx. Assuming this effect on upper airway calibre is not eliminated by sleep, mandibular advancement oral appliances may reduce the severity of obstructive sleep apnoea by maintaining patency of the velopharynx, particularly in its lateral dimension.

Adult↗
PubMed1998

Mandibular posture during sleep in healthy adults.

To test whether the mandible opens more during deep sleep and whether the mandibular position is affected by body position during sleep, the vertical mandibular position was recorded intraorally using a magnet sensor at the same time as a standard sleep study in seven normal healthy male adults. Measurements were recorded during the period before sleep onset (WAKE) and during sleep. Two-way ANOVA showed that vertical mandibular position was significantly affected by sleep stage but not by body position (supine vs lateral recumbent). The proportion of time during which the mandible was in a near-closed position (0-2.5 mm) significantly and progressively decreased, and significantly more time was spent at wider gaps (2.5-5 mm) as non-rapid-eye-movement (NREM) sleep deepened. In REM sleep, the proportion of time during which the mandible was at wider gaps was significantly greater than in WAKE and stage 1 (but not later stages) of NREM sleep. It was concluded that mandibular posture during sleep in healthy adults is significantly influenced by sleep stage but not by body position. Mandibular opening progressively increases with the depth of NREM sleep stage, and the mandible is more open in REM sleep than in light NREM sleep.

Adult↗
PubMed1998

Oropharyngeal airway dimensions and functional-orthopedic treatment in skeletal Class II cases.

Mandibular deficiency may be a factor in reduced oropharyngeal airway (OAW) dimensions and related impaired respiratory function. The purpose of this study was to evaluate the use of functional-orthopedic devices in increasing OAW dimensions in children with Class II skeletal patterns (ANB > 4) and clinically deficient mandibles. Comparisons were made between two groups, one comprising 26 treated patients and the other comprising 15 controls. Student's t-tests, paired t-tests, discriminant analyses, and Pearson's r-correlation coefficients were performed to evaluate group differences and to search for characteristics that might suggest which patients would be better candidates for significant increase in OAW dimensions. Compared with controls, OAW dimensions increased significantly in treated patients, especially those with sagittally smaller and more retrognathic maxillomandibular complexes and smaller OAW dimensions.

Activator Appliances↗
PubMed1998

Natural head posture, upper airway morphology and obstructive sleep apnoea severity in adults.

Enlarged tonsils, adenoids, and chronic respiratory problems have been associated with the compensatory adaptations of natural head posture (NHP) in children. Recently, it has been shown that adult patients with Obstructive Sleep Apnoea (OSA) also tend to exhibit a craniocervical extension (CCE) with a forward head posture (FHP). This study was designed to search for some characteristics of OSA patients that may be related to these adaptive changes in NHP. Overnight polysomnographic, demographic, and cephalometric records of 252 adult male subjects with various types of skeletal patterns and dental conditions were examined. Apnoea Index (AI) and Apnoea + Hypopnoea Index (AHI) variables were assessed to separate the non-apnoeic snorers (n = 35), and mild (n = 101), moderate (n = 63), and severe (n = 53) OSA groups. Results of the Tukey tests revealed that severe OSA patients had a greater tendency to exhibit a CCE with a FHP (P < or = 0.05 to P < or = 0.001). Differences in head extension (NSL.VER) between groups could not be identified. Pearson's 'r' correlation coefficients revealed that the CCE and FHP in OSA patients were associated with a higher disease severity, a longer and larger tongue, a lower hyoid bone position in relation to the mandibular plane, a smaller nasopharyngeal and a larger hypopharyngeal cross-sectional area, and a higher body mass index (P < or = 0.05 to P < or = 0.001). It is concluded that a CCE with a FHP is more likely to be seen in severe and obese OSA patients with certain morphological characteristics of the upper airway and related structures.

Adult↗
PubMed1997

A thin-plate spline analysis of the face and tongue in obstructive sleep apnea patients.

The shape characteristics of the face and tongue in obstructive sleep apnea (OSA) patients were investigated using thin-plate (TP) splines. A relatively new analytic tool, the TP spline method, provides a means of size normalization and image analysis. When shape is one's main concern, various sizes of a biologic structure may be a source of statistical noise. More seriously, the strong size effect could mask underlying, actual attributes of the disease. A set of size normalized data in the form of coordinates was generated from cephalograms of 80 male subjects. The TP spline method envisioned the differences in the shape of the face and tongue between OSA patients and nonapneic subjects and those between the upright and supine body positions. In accordance with OSA severity, the hyoid bone and the submental region positioned inferiorly and the fourth vertebra relocated posteriorly with respect to the mandible. This caused a fanlike configuration of the lower part of the face and neck in the sagittal plane in both upright and supine body positions. TP splines revealed tongue deformations caused by a body position change. Overall, the new morphometric tool adopted here was found to be viable in the analysis of morphologic changes.

Anthropometry↗
PubMed1997

A role of pharyngeal length in obstructive sleep apnea patients.

A narrow pharyngeal pathway may be one of the most significant predisposing factors for obstructive sleep apnea (OSA). Accordingly, the objectives of many treatment modalities are focused on widening the constricted part of the pharynx. Despite the obvious limitations as a two-dimensional imaging technique, cephalometrics has been used more recently as a clinical screening tool for OSA. This study was designed to investigate whether pharyngeal variables more reliable than a single measurement of the most constricted area exist in cephalograms. A total of 80 pairs of upright and supine cephalograms were obtained and subclassified into four groups, in accordance with OSA severity. A medial axis program conveniently provided the variables for the study by transforming digitized outlines of the pharyngeal structure. The results indicate that the pharyngeal length and the pharyngeal width below the most constricted area may be the most important variables. We observed that the pharynx becomes considerably longer in the apneic group after a body position change from upright to supine. Pharyngeal length in the supine position may be more important than a one-dimensional measurement of the most constricted area in the diagnosis and treatment of OSA.

Analysis of Variance↗
PubMed1997

Cephalometric and demographic characteristics of obstructive sleep apnea: an evaluation with partial least squares analysis.

Obstructive sleep apnea (OSA) is caused by repeated obstruction of the upper airway during sleep. The purpose of this study was to test the relative contributions of specific demographic and cephalometric measurements to OSA severity. Demographic, cephalometric, and overnight polysomnographic records of 291 male OSA patients and 49 male nonapneic snorers were evaluated. A partial least squares (PLS) analysis was used for statistical evaluation. The results revealed that the predictive powers of obesity and neck size variables for OSA severity were higher than the cephalometric variables used in this study. Compared with other cephalometric characteristics, an extended and forward natural head posture, lower hyoid bone position, increased soft palate and tongue dimensions, and decreased nasopharyngeal and velopharyngeal airway dimensions had relatively higher associations with OSA severity. The respiratory disturbance index (RDI) was the OSA outcome variable that was best explained by the demographic and cephalometric predictor variables. We conclude that the PLS analysis can successfully summarize the correlations between a large number of variables, and that obesity, neck size, and certain cephalometric measurements may be used together to evaluate OSA severity.

Adolescent↗