THE ROLE OF UPPER AIRWAY ANATOMY AND PHYSIOLOGY IN OBSTRUCTIVE SLEEP APNEA

Oral appliance therapy for the management of obstructive sleep apnea in adults: an umbrella review protocol

OBJECTIVE

The objective of this review is to summarize the evidence on the effectiveness of oral appliance therapy compared with other therapeutic approaches (continuous positive airway pressure, maxillomandibular and upper airway surgeries, behavioral techniques) for the management of obstructive sleep apnea in adults.

INTRODUCTION

For primary snoring, mild to moderate obstructive sleep apnea, and patients with a severe condition who are intolerant of continuous positive airway pressure therapy, an oral appliance is the treatment of choice among conservative procedures. The effectiveness of these appliances is largely determined by a variety of parameters, including the severity of sleep apnea (mild, moderate, severe), materials and methods used to fabricate the appliance, and the degree of mandibular protrusion. Thus, it is important to evaluate the effectiveness of oral appliances in the reduction of sleep apnea.

INCLUSION CRITERIA

This review will include systematic reviews of quantitative studies reporting on the effectiveness of oral appliances for the treatment of obstructive sleep apnea of any severity, confirmed using polysomnography. The primary outcome will be measured by reduction in the apnea-hypopnea index.

METHODS

A search will be conducted of MEDLINE, Cochrane Database of Systematic Reviews, Scopus, Web of Science, CINAHL, Epistemonikos, Embase, ProQuest Dissertations and Theses, and Shodhganga Dissertations and Theses from database inception until the present, with no language restrictions. Google Scholar will be searched manually. Two independent reviewers will screen titles, abstracts, and full-text articles and perform data extraction. Quality assessment will be conducted using the standard JBI critical appraisal tool. Data will be extracted from systematic reviews and a synthesis of the findings will be presented. The certainty will be assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE).

REVIEW REGISTRATION

PROSPERO CRD42021258515.

Correlation between dental arch form and OSA severity in adult patients: an observational study

BACKGROUND

The role of interdental widths and palatal morphology on the development of obstructive sleep apnea (OSA) has not been well investigated in adult patients yet. The aim of this paper was to assess the morphology of maxilla and mandibular dental arches on three-dimensional (3D) casts and to correlate these measurements with the severity of OSA.

METHODS

Sixty-four patients (8 women and 56 men, mean age 52.4) with a diagnosis of mild-to-moderate OSA were retrospectively enrolled. On each patient, home sleep apnea test and 3D dental models were collected. Apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) were recorded, as well as the dental measurements including inter-molar distance, anterior and posterior widths of maxillary and mandibular arches, upper and lower arch lengths, palatal height, and palatal surface area. The respiratory and dental variables were then correlated.

RESULT

A statistically inverse correlation was found between ODI and anterior width of lower arch, maxillary arch length, palatal height, and palatal area. AHI showed a significant inverse correlation with anterior width of mandibular arch and maxillary length.

CONCLUSION

A significant inverse correlation between maxillary and mandibular morphology and respiratory parameters was shown in the present paper.

The impact of thyroidectomy on obstructive sleep apnea: a systematic review and meta-analysis

PURPOSE

Various thyroid pathologies are speculated to contribute to obstructive sleep apnea (OSA). The underlying mechanisms of the intricate relationship between OSA and thyroid structure and function, and whether thyroidectomy can alleviate OSA symptoms remain unclear. An assessment of the impact of thyroidectomy on OSA is warranted.

METHODS

A systematic review of four electronic databases (PubMed (Medline), Embase, the Cochrane library, and ClinicalTrials.gov) was performed up to February 2022. The primary outcomes were preoperative and postoperative Apnea/Hypopnea Index (AHI), Epworth Sleepiness Scale (ESS), Berlin questionnaire scores, and continuous positive airway pressure (CPAP) use. A meta-analysis of continuous measures and odd ratios was conducted. Small-scale studies underwent a qualitative meta-analysis.

RESULTS

Six cohort studies on 221 OSA patients who underwent thyroidectomies were included. The results showed that thyroidectomy was associated with significant reduction in postoperative AHI (Mean difference [MD], -6.39, 95% CI, -12.46 to -0.32), however, no significant association was found with CPAP withdrawal (Odd ratio [OR], 0.38, 95% CI, 0.12-1.18). Neither the Berlin questionnaire score (OR, 0.19, 95% CI, 0.03-1.17) nor the ESS improved postoperatively (MD, -1.04, 95% CI, -6.37 to 4.29).

CONCLUSION

This meta-analysis provides a quantitative estimate for the effect of the thyroidectomy on OSA and suggests that thyroidectomy is associated with limited clinical improvement of polysomnographic measures. Future large-scale, well-designed prospective studies are necessary to validate these findings and to refine accordingly the preoperative assessment of both medical conditions individually and in combination.

Arch Measurement Changes upon Biomimetic Oral Appliance Therapy for Adults with Obstructive Sleep Apnea

Background:

Obstructive Sleep Apnea (OSA) is the most common form of sleep disordered breathing. Patients who arrive at the dental office with a diagnosis of OSA are often treated with a mandibular advancement device (MAD). A biomimetic oral appliance therapy (BOAT) offers an alternative nonsurgical method, which can putatively resolve OSA by combining maxilla-mandibular correction and addressing craniofacial deficiencies.

Aim:

To determine whether maxilla-mandibular correction changes induced by BOAT produce a more favorable upper airway, which might result in a reduction in the severity of OSA.

Methods:

Patients who were diagnosed with mild to moderate obstructive sleep apnea (OSA, 9 males, 8 females; age, mean (SD): 45.76(10.31), BMI mean (SD): 33.5(13.43), underwent BOAT therapy. Subjects had 2 months of follow-up visits, including examinations for progress and adjustment of the appliances. The mean apnea-hypopnea index (AHI) with no appliance in the mouth prior to BOAT and after treatment was recorded. The mid-palatal screw mechanism of the appliance was advanced once per week. The subjects were asked to wear the appliance for 10-12 hours/day and night. Paired T-Test was used to analyze the results.

Results:

The BOAT treatment enhanced upper airway function as the total AHI was significantly lower after treatment (P=0.019). Parameters that were significantly improved by the end of the treatment period included total AHI/Per hour of sleep (p=0.019), NREM-AHI (p=0.019), desaturation index (p=0.041), average SpO2 (p=0.088), and average O2 while in non-REM (p=0.043). Measurements of jaw changes were all statistically significant except lower 6-6 and lower 7-7. Additionally, a strong negative correlation between AHI and jaw changes was shown for upper 6-6 (p=-0.52), upper 7-7 (p=-0.48), and lower 3-3 (p=-0.42).

Conclusion:

The BOAT provides a useful form of therapy for the resolve of OSA. This study suggests that BOATS may be able to reduce the AHI to within normal limits. Still, long-term follow-up is needed to determine whether these subjects need a maintenance program to retain their initial upper airway improvement.

The effect of allergic rhinitis on the degree of stress, fatigue and quality of life in OSA patients

Both allergic rhinitis (AR) and obstructive sleep apnea (OSA) are known to increase stress and fatigue, but the result of their coexistence has not been studied. The objective of this study was to evaluate the amount of stress and fatigue when AR is combined with OSA. One hundred and twelve patients diagnosed with OSA by polysomnography were enrolled. Among them, 37 patients were diagnosed with AR by a skin prick test and symptoms (OSA-AR group) and 75 patients were classified into the OSA group since they tested negative for allergies. We evaluated the Epworth sleepiness scale (ESS), stress score, fatigue score, ability to cope with stress, and rhinosinusitis quality of life questionnaire (RQLQ) with questionnaires and statistically compared the scores of both groups. There were no significant differences in BMI and sleep parameters such as LSAT, AHI, and RERA between the two groups. However, the OSA-AR group showed a significantly higher ESS score compared to the OSA group (13.7 ± 4.7 vs. 9.3 ± 4.8). Fatigue scores were also significantly higher in the OSA-AR group than in the OSA group (39.8 ± 11.0 vs. 30.6 ± 5.4). The OSA-AR group had a significantly higher stress score (60.4 ± 18.6 vs. 51.2 ± 10.4). The ability to cope with stress was higher in the OSA group, although this difference was not statistically significant. RQLQ scores were higher in the OSA-AR group (60.2 ± 16.7 compared to 25.1 ± 13.9). In conclusion, management of allergic rhinitis is very important in treating OSA patients in order to eliminate stress and fatigue and to minimize daytime sleepiness and quality of life.

Modified mandibular advancement appliance for an edentulous obstructive sleep apnea patient: a clinical report

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder with periodic reduction or cessation of airflow during sleep. It is associated with loud snoring, disrupted sleep and observed apneas with prevalence up to 54% in elderly people. Treatment of OSA varies from simple measures such as dental appliances and nasal continuous positive airway pressure (CPAP) to surgical procedures like uvulopalatopharyngoplasty and tracheostomy. Dental appliances are a viable nonsurgical treatment alternative in patients with OSA, of which mandibular advancement appliances are most common. Edentulism which contributes to the worsening of OSA reduces the number of available therapeutic strategies and is considered a contraindication to oral appliance therapy. This clinical report describes the treatment of a 61-year old edentulous OSA patient for whom a modified mandibular advancement appliance was designed. The patient reported an improvement in AHI index and he was satisfied with the modified appliance. This clinical report describes the newer technique of fabricating oral appliance for edentulous OSA patient.

Facial profile shape, malocclusion and palatal morphology in Malay obstructive sleep apnea patients

OBJECTIVE

To test the null hypothesis that there is no difference in facial profile shape, malocclusion class, or palatal morphology in Malay adults with and without obstructive sleep apnea (OSA).

MATERIALS AND METHODS

Subjects were 120 adult Malays aged 18 to 65 years (mean +/- standard deviation [SD], 33.2 +/- 13.31) divided into two groups of 60. Both groups underwent clinical examination and limited channel polysomnography (PSG). The mean OSA and control values were subjected to t-test and the chi square test.

RESULTS

Physical examination showed that 61.7% of the OSA patients were obese, and 41.7% of those obese patients had severe OSA. The mean body mass index (BMI) was significantly greater for the OSA group (33.2 kg/m2 +/- 6.5) than for the control group (22.7 kg/m2 +/- 3.5; P < .001). The mean neck size and systolic blood pressure were greater for the OSA group (43.6 cm +/- 6.02; 129.1 mm Hg +/- 17.55) than for the control group (35.6 cm +/- 3.52; 114.1 mm Hg +/- 13.67; P < .001). Clinical examination showed that the most frequent findings among OSA groups when compared with the control group were convex profiles (71.7%), Class II malocclusion (51.7%), and V palatal shape (53.3%), respectively; the chi square test revealed a significant difference in terms of facial profile and malocclusion class (P < .05), but no significant difference in palatal shape was found.

CONCLUSION

The null hypothesis is rejected. A convex facial profile and Class II malocclusion were significantly more common in the OSA group. The V palatal shape was a frequent finding in the OSA group.

Treatment outcomes of mandibular advancement devices in positional and nonpositional OSA patients

OBJECTIVE

The aim of the study was to investigate treatment outcome of mandibular advancement devices (MADs) for positional and nonpositional obstructive sleep apnea (OSA).

STUDY DESIGN

Forty-two positional (supine apnea-hypopnea index [AHI] > or = 2 times lateral AHI) and 30 nonpositional (supine AHI < 2 times lateral AHI) OSA patients performed 2-nights of sleep study before and after insertion of MADs.

RESULTS

The decreases in apnea severity based on a reduction in the overall and supine AHI values after MADs therapy were significantly greater for the positional OSA than nonpositional OSA group. A multiple linear regression analysis showed that decrease in overall AHI was significantly associated with being in the positional group (standardized coefficient = 0.505). Age, body mass index, gender, and time in supine position during sleep did not show significant associations with decrease in overall AHI after MAD therapy.

CONCLUSION

Our data suggest that MADs are more effective in positional OSA than nonpositional OSA patients.

Evaluation of airway obstruction by nasopharyngoscopy: comparison of the Müller maneuver versus induced sleep

The use of nasopharyngoscopy during the application of intrathoracic pressure (Müller maneuver) is frequently employed to establish the site of upper airway obstruction. The Müller maneuver, however, is used when the patient is awake and therefore may not correlate with obstruction occurring during sleep. Aim: to compare the degree of pharyngeal obstruction in the retropalatal and retroglossal regions during the Müller maneuver versus induced sleep using nasopharyngoscopy. Study design: A prospective, case series study. Material and methods: Eight patients (three males, five females), with a mean age of 48.6 +/- 9,2 year, underwent nasopharyngoscopy to assess airway anatomy and funciton during the Müller maneuver while awake and during sleep induced by drip infusion of Midazolam. Results: Retropalatal obstruction was similar during the Müller maneuver and sleep (mean + standard deviation = 3.13 +/- 0.99 and 2.75 +/- 0.46, p= 0.234). Retroglossal obstruction was significantly lower during Müller maneuver compared to sleep (mean + standard deviation 0.63 +/- 1.06 and 2.63 +/- 1.30, respectively, p= 0.005). Conclusion: The sleep inducing method was safe under the monitored conditions of this study, and detected more retroglossal obstruction than the Müller maneuver.

Avaliação da obstrução da via aérea superior através da videonasofaringoscopia: comparação da manobra de Müller com o sono induzido

A nasofaringoscopia com realização de Manobra de Müller é freqüentemente utilizada para determinar o local da obstrução na via aérea superior. No entanto, sua utilidade é controversa, uma vez que é realizada com o paciente acordado e pode não reproduzir os fenômenos obstrutivos que ocorrem durante o sono. OBJETIVOS: Comparar o grau de obstrução faríngea nas regiões retropalatal e retrolingual que ocorrem durante a manobra de Müller com aquelas que ocorrem durante o sono induzido. MATERIAL E MÉTODOS: Estudo prospectivo de 8 pacientes (3 homens e 5 mulheres) com idade (média ±desvio padrão) de 48,6 ± 9,2 anos de idade através de videonasofaringoscopia durante a manobra de Müller e durante o sono induzido por midazolam endovenoso. RESULTADOS: Observamos obstrução retropalatal similar durante a manobra de Müller e sono induzido (média + desvio padrão 3,13 + 0,99 e 2,75 + 0,46, respectivamente, p= 0,234). Em contraste, a obstrução retrolingual foi significantemente menor durante a manobra de Müller (média + desvio padrão 0,63 + 1,06 e 2,63 + 1,30, respectivamente, p= 0,005). CONCLUSÃO: O método do sono induzido foi seguro sob as condições de monitorização adotadas, tendo detectado maior ocorrência de colapso retrolingual do que a manobra de Müller.

Oral appliances for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea-hypopnoea (OSAH) is a syndrome characterised by recurrent episodes of partial or complete upper airway obstruction during sleep that are usually terminated by an arousal. Nasal continuous positive airway pressure (CPAP) is the primary treatment for OSAH , but many patients are unable or unwilling to comply with this treatment. Oral appliances (OA) are an alternative treatment for OSAH.

OBJECTIVES

The objective was to review the effects of OA in the treatment of OSAH in adults.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register. Searches were current as of June 2005. Reference lists of articles were also searched.

SELECTION CRITERIA

Randomised trials comparing OA with control or other treatments in adults with OSAH .

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Study authors were contacted for missing information.

MAIN RESULTS

Sixteen studies (745 participants) met the inclusion criteria. All the studies had some shortcomings, such as small sample size, under-reporting of methods and data, and lack of blinding. OA versus control appliances (six studies): OA reduced daytime sleepiness in two crossover trials (WMD -1.81;95%CI -2.72 to -0.90), and improved apnoea-hypopnoea index (AHI) (-10.78; 95% CI-15.53 to -6.03 parallel group data - five studies). OA versus CPAP (nine studies): OA were less effective than CPAP in reducing apnoea-hypopnoea index (parallel group studies: WMD 13 (95% CI 7.63 to 18.36), two trials; crossover studies: WMD 7.97; (95% CI 6.38 to 9.56, seven trials). However, no significant difference was observed on symptom scores. CPAP was more effective at improving minimum arterial oxygen saturation during sleep compared with OA. In two small crossover studies, participants preferred OA therapy to CPAP. OA versus corrective upper airway surgery (one study): Symptoms of daytime sleepiness were initially lower with surgery, but this difference disappeared at 12 months. AHI did not differ significantly initially, but did so after 12 months in favour of OA.

AUTHORS' CONCLUSIONS

There is increasing evidence suggesting that OA improves subjective sleepiness and sleep disordered breathing compared with a control. CPAP appears to be more effective in improving sleep disordered breathing than OA. The difference in symptomatic response between these two treatments is not significant, although it is not possible to exclude an effect in favour of either therapy. Until there is more definitive evidence on the effectiveness of OA in relation to CPAP, with regard to symptoms and long-term complications, it would appear to be appropriate to recommend OA therapy to patients with mild symptomatic OSAH, and those patients who are unwilling or unable to tolerate CPAP therapy. Future research should recruit patients with more severe symptoms of sleepiness, to establish whether the response to therapy differs between subgroups in terms of quality of life, symptoms and persistence with usage. Long-term data on cardiovascular health are required.

Quantitative computer-assisted digital-imaging upper airway analysis for obstructive sleep apnoea

This was a prospective study of a new objective method which quantitatively analyses the upper airways in patients with obstructive sleep apnoea (OSA). Video-nasopharyngoscopic examinations of the upper airways of 45 patients were carried out with an endoscopic calibrator. Images of the upper airway during quiet respiration and Mueller's manoeuvre in erect and supine positions were digitized by computer to generate the actual dimensions of obstructive sites. Measurements by the new method were validated by comparing 90 pairs of videoendoscopic images with upper airway magnetic resonance imaging (MRI) measurements at two identical levels. Quantitative precision is 100% for the retropalatal level and 95.6% for the retrolingual level with a tolerance of 0.5 cm(2) between the two methods. The absolute mean of the difference between the two methods of measurement is 0.08 cm(2) at the retropalatal level and 0.18 cm(2) at the retrolingual level. The agreement between the digital-imaging videoendoscopic and MRI measurements was 93.3% for the retropalatal level and 95.6% for the retrolingual level. Quantitative computer-assisted digital imaging is a reliable, cost-effective clinical method of upper airway evaluation in OSA patients. This method allows us to examine the dynamic and static morphology objectively, measure surgical outcomes of upper airway, opening up new avenues for OSA management.

Oral appliances for obstructive sleep apnoea

BACKGROUND

Obstructive sleep apnoea-hypopnoea is a syndrome characterised by recurrent episodes of partial or complete upper airway obstruction during sleep that are usually terminated by an arousal. Nasal continuous positive airway pressure is the primary treatment for obstructive sleep apnoea-hypopnoea, but many patients are unable or unwilling to comply with this treatment. Oral appliances are an alternative treatment for sleep apnoea.

OBJECTIVES

The objective was to review the effects of oral appliance in the treatment of sleep apnoea in adults.

SEARCH STRATEGY

We searched the Cochrane Airways Group Sleep Apnoea RCT Register. Searches were current as of June 2004. Reference lists of articles were also searched.

SELECTION CRITERIA

Randomised trials comparing oral appliance with control or other treatments in adults with sleep apnoea.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and two reviewers extracted data independently. Study authors were contacted for missing information.

MAIN RESULTS

Thirteen trials involving 553 participants were included. All the studies had some shortcomings, such as small sample size, under-reporting of methods and data, and lack of blinding. Oral appliances versus control appliances (five studies): Oral appliances reduced daytime sleepiness in two crossover trials (WMD -1.81 [95%CI: -2.72, -0.90]), and improved apnoea-hypopnoea index (AHI) (-13.17 [-18.53 to -7.80] parallel group data - four studies). Oral appliances versus CPAP (seven studies): Oral appliances were less effective than continuous positive pressure in reducing apnoea-hypopnoea index (WMD 13 [95% CI: 7.63, 18.36], parallel studies - two trials; WMD 6.96 [4.82, 9.10] cross-over studies - six trials). However, no significant difference was observed on symptom scores. Nasal continuous positive pressure was more effective at improving minimum arterial oxygen saturation during sleep compared with oral appliance. In two small crossover studies, participants preferred oral appliance therapy to continuous positive airways pressure. Oral appliances versus surgery (one study): Symptoms of daytime sleepiness were initially lower with surgery, but this difference disappeared at 12 months. AHI did not differ significantly initially, but did so after 12 months in favour of OA.

REVIEWERS' CONCLUSIONS

There is some evidence suggesting that oral appliance improves subjective sleepiness and sleep disordered breathing compared with a control. Nasal continuous positive airways pressure appears to be more effective in improving sleep disordered breathing than oral appliance. Until there is more definitive evidence on the effectiveness of oral appliances, it would appear to be appropriate to restrict oral appliance therapy to patients with sleep apnoea who are unwilling or unable to comply with continuous positive airways pressure therapy.

Soft palate implants: a new option for treating habitual snoring

One hundred six patients with proven habitual snoring were each treated with three implants consisting of a cylindrical-shaped segment of braided polyester filaments (18 mm in length with an outer diameter of 1.5 mm) in the soft palate. The implants, pre-loaded in a single-use delivery tool, were inserted into the soft palate under local anesthesia. Along with the initial examination, follow-up exams were done after the treatment to test the safety and efficacy of the procedure. Snoring post treatment was reported as "no snoring" or "slight/occasional" in the majority of the cases after treatment. The results indicate there were no serious adverse events reported. The most frequent minor adverse events were partial extrusions in which the patient often presented a minor foreign body sensation along with mild transient pain. This data has demonstrated the procedure as a minimally invasive, relatively painless, simple procedure that has been shown to be safe and effective.

An investigation into the relationship between the severity of obstructive sleep apnoea/hypopnoea syndrome and the vertical position of the hyoid bone

OBJECTIVE

This study aimed to identify a correlation of diagnostic clinical significance between the vertical position of the hyoid bone in relation to structures within the dentofacial skeleton and: (1) The severity of obstructive sleep apnoea hypopnoea syndrome, (OSAHS), (2) Decisions relating to the management of the condition.

DESIGN AND SETTING

Randomised retrospective survey of cephalometric records of subjects having been diagnosed as suffering with OSAHS by in patient overnight polysomnographic testing at the Edinburgh Royal Infirmary Sleep Centre, 2001-2002.

MATERIALS AND METHODS

Pre-polysomnograph orthoposition lateral cephalograms of 94 subjects tested, during the period from April 1996 to September 1997, were randomly selected and traced following strict adherence to standard protocol. Edentulous arches (one or both) formed the only exclusion criterion owing to obvious effects upon vertical dimensions of the cervico-pharyngeal region. Measurement of the vertical position of the hyoid bone was made relative to a number of planes validated by numerous previous cephalometric investigations, and these were recorded along with the apnoea/hypopnoea index (AHI), and subsequent management (mandibular repositioning appliances (MRA) / continuous positive airway pressure (CPAP)). Correlations between measurements and AHI were investigated using Spearman's Correlation Coefficients, and analysis of the relationship between hyoid bone position and management groups was undertaken using Wilcoxon Ranked Sum Testing.

DISCUSSION AND RESULTS

Statistically significant correlations were found between all linear measurements locating the hyoid bone in the vertical plane and subject AHI. The linear relationships were less reliable for subjects with AHI > 100, possibly due to a breakdown in the body's ability to respond posturally in order to maintain airway patency in more extreme cases. When the treatment groups (MRA/CPAP) were considered independently there was found to be a clear delineation between the two groups at a length of 120 mm between the sella (S- a point upon the anterior cranial base) and the hyoid (H). This, in turn, may suggest that cephalometric radiographs may be used as a reproduciable diagnostic tool.

Polysomnographic effects of nasal surgery for snoring and obstructive sleep apnea

OBJECTIVE

It has been hypothesized that nasal obstruction causes an increase in negative pressure in the upper airway and induces an inspiratory collapse at the pharyngeal level. We used portable polysomnography (PSG) to assess the efficacy of nasal surgery for snoring and obstructive sleep apnea (OSA).

MATERIAL AND METHODS

We reviewed 21 patients who presented with nasal obstruction and snoring. Septal surgery with or without inferior turbinectomy was performed. Each patient was assessed pre- and postoperatively using PSG. We measured the respiratory distress index (RDI), apnea index (AI), oxygen saturation index (OSI) and the duration of snoring. Selection criteria were an RDI of > 15 as determined by PSG and clinical nasal obstruction and a deviated nasal septum as determined by physical examination.

RESULTS

Nasal surgery had the following effects: RDI decreased from 39 to 29 (p = 0.0001), AI decreased from 19 to 16 (p = 0.0209), OSI decreased from 48 to 32 (p = 0.0001) and the duration of snoring decreased from 44% to 39% (p = 0.1595). Snoring and OSA were completely relieved in 4 patients (19%) who did not require any additional surgical therapy.

CONCLUSION

Snoring and OSA may be corrected merely by septal surgery in some patients, and secondary surgery (uvulopalatoplasty) may be considered after a thorough evaluation by means of postoperative PSG.

Determining the site of airway obstruction in obstructive sleep apnea with airway pressure measurements during sleep

OBJECTIVE

To determine the site(s) of upper airway obstruction in patients with obstructive sleep apnea syndrome (OSAS) and their changes during sleep with upper airway (UA) pressure measurement; and to analyze the correspondence between the UA pressure measurement and polysomnography (PSG).

METHOD

Thirty patients with OSAS underwent UA pressure measurement. The catheter with five solid-state ultraminiature sensors was inserted through the patients' upper airway to the esophagus. The sensors were located at the nasopharynx, oropharynx, tongue base, hypopharynx, and esophagus. The lower limit of UA obstruction was determined by relying on the observed pressure pattern.

RESULT

1) During inspiration, obstruction occurred associated with an increased negative inspiratory pressure inferior to the site of obstruction and a disappeared negative inspiratory pressure above the site of obstruction; 2) three patterns of obstruction were observed; 3) the site of obstruction was located at the site of the palate; 4) velopharyngeal obstruction and tongue-pharynx obstruction were all present; 5) nasopharyngeal obstruction velopharyngeal obstruction and tongue-pharynx obstruction were all present; and 6) peak inspiratory pressure differences between the normal breath and apnea were associated with the longest apnea interval (P <.05).

CONCLUSION

UA pressure measurement can evaluate the site of obstruction in patients with OSAS and their changes during sleep. Peak inspiratory pressure differences between normal breath and apnea can show the severity of OSAS.

Physical findings and the risk for obstructive sleep apnea. The importance of oropharyngeal structures

In this study, we hypothesized that anatomic abnormalities of the oropharynx, particularly narrowing of the airway by the lateral pharyngeal walls, tonsils, and tongue, would be associated with an increased likelihood for obstructive apnea among patients presenting to a sleep disorders center. To test this hypothesis, we used data from a cohort of 420 patients presenting to the Penn Center for Sleep Disorders. Associations between individual variables in the clinical evaluation model and sleep apnea as defined by a respiratory disturbance index greater than or equal to 15 events per hour were characterized by odds ratios (ORs) with 95% confidence intervals (CIs). Multivariable logistic regression was used to simultaneously estimate ORs for multiple variables and to control for other relevant patient characteristics. Results showed that narrowing of the airway by the lateral pharyngeal walls (OR = 2.5; 95% CI, 1.6-3.9) had the highest association with obstructive sleep apnea (OSA) followed by tonsillar enlargement (OR = 2.0; 95% CI, 1.0-3.8), enlargement of the uvula (OR = 1.9; 95% CI, 1.2-2.9), and tongue enlargement (OR = 1.8; 95% CI, 1.0-3.1). Low-lying palate, retrognathia, and overjet were not found to be significantly associated with OSA. Controlling for BMI and neck circumference, only lateral narrowing and enlargement of the tonsils maintained their significant (OR = 2.0 and 2.6, respectively). A subgroup analysis examining differences between male and female subjects showed that no oropharyngeal risk factor achieved significance in women while lateral narrowing was the sole independent risk factor in men. These findings suggest that enlargement of the oropharyngeal soft tissue structures, particularly the lateral pharyngeal walls, is associated with an increased likelihood of OSA among patients presenting to sleep disorders centers.

Upper airway assessment: radiographic and other imaging techniques

Upper airway imaging is a powerful technique to study the mechanisms underlying the pathogenesis and biomechanics of sleep apnea and the mechanisms underlying the efficacy of therapeutic interventions in patients with sleep disordered breathing. The primary upper airway imaging modalities include nasopharyngoscopy, cephalometrics, CT scanning, and MR imaging. Imaging studies using these modalities have provided important insights into the static and dynamic structure and function of the upper airway and surrounding soft-tissue structures during wakefulness and sleep. Such imaging studies have highlighted the importance of the lateral pharyngeal walls in mediating upper airway caliber. These imaging modalities have also been used to study the effect of respiration, weight loss, mandibular repositioning devices, and upper airway surgery on the upper airway. Three-dimensional reconstruction of the airway and surrounding soft-tissue structures can be performed with MR imaging and CT scanning. Clinical indications for upper airway imaging are evolving such that imaging studies should be considered in patients with sleep apnea who are being treated with dental appliances or upper airway surgery.

Upper airway imaging

Upper airway imaging is a powerful technique to study the mechanisms underlying the pathogenesis, biomechanics, and efficacy of treatment options in patients with obstructive sleep apnea. Imaging studies have provided significant insight into the static and dynamic structure, and function of the upper airway and surrounding soft-tissue structure during wakefulness and sleep. Upper airway imaging modalities primarily include nasopharyngoscopy, cephalometrics, computed tomography (CT), and magnetic resonance (MR) scanning. These imaging modalities have been used to study the effect of respiration, weight loss, dental appliances, and upper airway surgery on the upper airway. MR imaging and CT have allowed quantification of the airway and surrounding soft-tissue structures in three dimensions. Clinical indications for upper airway imaging are evolving for patients being treated with dental appliances and upper airway surgery.

Positional vs nonpositional obstructive sleep apnea patients: anthropomorphic, nocturnal polysomnographic, and multiple sleep latency test data

STUDY OBJECTIVES

To compare anthropomorphic, nocturnal polysomnographic (PSG), and multiple sleep latency test (MSLT) data between positional (PP) and nonpositional (NPP) obstructive sleep apnea (OSA) patients.

DESIGN

This is a retrospective analysis of anthropomorphic, PSG, and MSLT data of a large group of OSA patients who underwent a complete PSG evaluation in our sleep disorders unit. The patients were divided in two groups: the PP group, those patients who had a supine respiratory disturbance index (RDI) that was at least two times higher than the lateral RDI, and the NPP group, those patients in whom the RDI in the supine position was less than twice that in the lateral position.

SUBJECTS

From a group of 666 consecutive OSA patients whose conditions were diagnosed in our unit from September 1990 to February 1995, 574 patients met the following criteria and were included in the study: RDI > 10; age > 20 years, and body mass index (BMI) > 20.

RESULTS

Of all 574 patients, 55.9% were found to be positional. No differences in height were observed but weight and BMI were significantly higher in the NPP group, these patients being on the average 6.5 kg heavier than those in the PP group. The PP group was, on average, 2 years younger than the NPP group. Nocturnal sleep quality was better preserved in the PP group. In this group, sleep efficiency and the percentages of deep sleep (stages 3 and 4) were significantly higher while the percentages of light sleep (stages 1 and 2) were significantly lower than in the NPP group. No differences for rapid eye movement (REM) sleep were found. In addition, wakefulness after sleep onset and the number of short arousals (< 15 s) were significantly lower in the PP group. Apnea index and total RDI were significantly higher and the minimal arterial oxygen saturation in REM and non-REM sleep was significantly lower in the NPP. No differences in periodic limb movements data were found between the two groups. The average MSLT was significantly shorter in the NPP group. Univariate and multivariate stepwise logistic regression analysis showed that the most dominant variable that correlates with positional dependency in OSA patients is RDI, followed by BMI which also adds a significant contribution to the prediction of positional dependency. Age, although significant, adds only a minor improvement to the prediction of this positional dependency phenomenon. A severe, obese, and older OSA patient is significantly less likely to be positional than a mild-moderate, thin, and young OSA patient. In four obese OSA patients who lost weight, a much more pronounced reduction was seen in the lateral RDI than in the supine RDI, and three of these cases who were previously NPP became PP.

CONCLUSIONS

In a large population of OSA patients, most were found to have at least twice as many apneas/hypopneas in the supine than in the lateral position. These so-called "positional patients" are on the average thinner and younger than "nonpositional patients." They had fewer and less severe breathing abnormalities than the NPP group. Consequently their nocturnal sleep quality was better preserved and, according to MSLT data, they were less sleepy during daytime hours. RDI was the most dominant factor that could predict the positional dependency followed by BMI and age. RDI showed a threshold effect, the prevalence of PP in those with severe RDI (RDI > or = 40) was significantly lower than in those OSA patients with mild-moderate RDI. BMI showed a major significant inverse relationship with positional dependency, while age had only a minor although significant inverse relationship with it. Body position during sleep has a profound effect on the frequency and severity of breathing abnormalities in OSA patients.

Sleep apnea: a challenge in critical care

Sleep apnea, defined as the cessation of breathing for at least 10 seconds during sleep, can have detrimental effects on the critically ill. Three types of sleep apnea exist, the most common being obstructive sleep apnea. Though its prevalence is only 1% to 3% in adults, it is very important to diagnose it and treat it early in the critically ill because it causes respiratory failure and difficult weaning from mechanical ventilation. Its most characteristic manifestations are repetitive apneic episodes during sleep, snoring, and diurnal hypersomnolence. Complications of sleep apnea include dysrhythmias, systemic and pulmonary hypertension, hypoxia, hypoventilation, left ventricular dysfunction, and stroke. Treatment methods depend on the cause and include medications, surgery, and nasal continuous positive airway pressure. The main nursing role is astute assessment and early detection, proper respiratory management, provision of psychologic support, and patient and family teaching.

Ischemic hepatitis due to obstructive sleep apnea

The case of an obese patient who developed massive centrilobular liver cell necrosis, severe coagulopathy, acute renal failure, and encephalopathy is presented. Hypovolemia and heart failure were absent, but the acute liver disease was associated with severe arterial hypoxemia due to obstructive sleep apnea that was shown by the nocturnal blood oxygen desaturation, the results of the polysomnographic study, and normal baseline pulmonary function tests. In this obese patient, liver cell necrosis was caused by severe liver cell hypoxia secondary to severe arterial hypoxemia as a consequence of obstructive sleep apnea associated with a Pickwickian syndrome. This observation is consistent with the hypothesis that liver ischemia was directly related to severe arterial hypoxemia.

Treatment of obstructive sleep apnea in pediatric patients. Behavioral intervention for compliance with nasal continuous positive airway pressure

This study evaluated the efficacy of behavioral techniques (i.e., parent training, modeling, and desensitization) to facilitate use of nasal continuous positive airway pressure (CPAP) in four children with obstructive sleep apnea (OSA) secondary to anatomic disorder of the upper airway. All patients tolerated CPAP with training: Polysomnographic data revealed improvement in sleep architecture, apnea, and oxygenation, and patients were discharged on CPAP units. All patients continued to use CPAP throughout the 3-month follow-up period and none required additional treatment for OSA. Three of four patients continued to use CPAP at the 9-month follow-up visit. Treatment resulted in improvements in alertness, attention/concentration, and behavior/temperament. Children generally have been considered poor candidates for nasal CPAP, and historically they have been offered instead more invasive procedures. This study suggests that CPAP is a viable treatment for such children when paired with behavioral interventions that facilitate its use.

Obstructive sleep apnea

The high prevalence of obstructive sleep apnea (OSA) has only recently been appreciated, in part because the symptoms and signs of chronic sleep disruption are often overlooked in spite of their debilitating consequences. They typically develop insidiously during a period of years. We now know that the lives of millions of people each year are significantly impaired by the sequelae of OSA. Many of these patients go unrecognized, with tremendous medical and economic consequences for individual patients and for society. Evidence indicates that chronic, heavy snoring may be associated with increased long-term cardiovascular and neurophysiologic morbidity. Therefore considerable interest lies in the study of the epidemiology and the natural history of these related disorders. The fundamental problem in OSA is the periodic collapse of the pharyngeal airway during sleep. The pathophysiology of this phenomenon is reviewed in some detail. During apneas caused by obstruction, airflow is impeded by the collapsed pharynx in spite of continued effort to breathe. This causes progressive asphyxia, which increasingly stimulates breathing efforts against the collapsed airway, typically until the person is awakened. Hypopneas predominate in some patients and are caused by partial pharyngeal collapse. The clinical sequelae of OSA relate to the cumulative effects of exposure to periodic asphyxia and to sleep fragmentation caused by apneas and hypopneas. Some patients with frequent, brief apneas and hypopneas and normal underlying cardiopulmonary function may have considerable sleep disruption without much exposure to nocturnal hypoxia. Patients with sleep apnea often have excessive daytime sleepiness. As the disorder progresses, sleepiness becomes increasingly irresistible and dangerous, and patients develop cognitive dysfunction, inability to concentrate, memory and judgment impairment, irritability, and depression. These problems may lead to family and social problems and job loss. Cardiac and vascular morbidity in OSA may include systemic hypertension, cardiac arrhythmias, pulmonary hypertension, cor pulmonale, left ventricular dysfunction, stroke, and sudden death. The challenge for the clinician is to routinely consider the diagnosis and to incorporate several basic questions in the historical review of systems regarding daytime or inappropriate sleepiness. The diagnosis of OSA is made with polysomnography, and the decision to treat is based on an overall assessment of the severity of sleep-disordered breathing, sleep fragmentation, and associated clinical sequelae. The therapeutic options for the management of OSA are reviewed. Recognition and appropriate treatment of OSA and related disorders will often significantly enhance the patient's quality of life, overall health, productivity, and safety on the highways.