Maxillomandibular advancement surgery in patients with obstructive sleep apnea: mandibular morphology and stability

Causal associations between various craniofacial morphologic variables and obstructive sleep apnea have been inferred and serve to justify many treatments. The purposes of this study were to examine the presurgical and postsurgical mandibular morphology of patients with obstructive sleep apnea who were undergoing maxillomandibular advancement and to assess the stability of the observed changes. Various mandibular morphologic variables of 32 male subjects were measured on presurgical, immediately postsurgical, and short-term and long-term postsurgical radiographs. The results demonstrated that presurgical mandibular morphology was not significantly different from that of control samples derived from the literature. The presurgical mandibular plane-hyoid measurement was an average of 11.4 mm greater than that in matched controls. On average, surgery resulted in a significantly longer mandible, a greater gonial angle, and a reduced mandibular plane-hyoid distance, although the response of the hyoid was quite variable. The surgical changes in mandibular length were relatively stable over the long-term. Obstructive sleep apnea did not appear to be related to abnormal presurgical mandibular morphology in this sample.     

Upper airway bypass surgery for obstructive sleep apnea syndrome

This article reviews the history of tracheostomy for sleep apnea syndrome along with current indications for temporary and permanent tracheostomy in these patients. Because most patients requiring tracheostomy for obstructive sleep apnea syndrome are morbidly obese and have a short thick neck, a skin-lined technique has been developed. This technique is described along with preoperative and postoperative care necessary to allow uneventful healing and prevent complications. Surgical techniques available for tracheostomy closure are also described.     

Pulmonary hypertension in patients with obstructive sleep apnea syndrome

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is associated with an increased cardiovascular morbidity, including pulmonary hypertension. Little is known about factors influencing the degree of pulmonary hypertension and left ventricular dysfunction in patients with OSAS, especially in the absence of concomitant lung disease. METHODS: Right heart catheterization, arterial blood gas analysis, and pulmonary function tests were performed in 92 consecutive patients (81 men and 11 women; mean +/- SD age, 53.1 +/- 11.0 years) with polysomnographically verified OSAS, in whom clinically significant lung disease was excluded. RESULTS: Eighteen patients (20%) had mild pulmonary hypertension; 8 (44%) of them also had increased pulmonary capillary wedge pressures (Ppew). Left ventricular dysfunction was associated with arterial hypertension. Only Ppcw (r = 0.51; P < .001) and the percentage of time during sleep spent with an oxygen saturation below 90% (as an indicator of the severity of OSAS) (r = 0.34; P = .003) were significantly and independently associated with pulmonary artery pressure. CONCLUSIONS: Obstructive sleep apnea syndrome can cause mild pulmonary hypertension, even in the absence of pulmonary disease. In these patients, pulmonary hypertension is of the postcapillary type, or-in patients with normal left ventricular function-strongly related to the severity of OSAS. Our findings indicate that OSAS may constitute an important, and independent, risk factor for pulmonary hypertension.     

Sex-specific sleep anamnesis in obstructive sleep apnea syndrome?

Although the prevalence of obstructive sleep apnea syndrome (OSAS) is about 4% in men and 2% in women, women are underrepresented in clinical routine. The aim of this study was to determine whether differences in clinical features of OSAS may in part explain the bias observed. 224 men and 24 women with polysomnographically confirmed OSAS filled in a symptom-focussed multiple-choice questionnaire. Polysomnographical results were comparable in both groups. With regard to snoring, daytime sleepiness and tendency of falling asleep there were no differences between both groups. Women more frequently complained about difficulties of initiating and maintaining sleep and about apneas. Further investigations have to concentrate on the pathomechanisms of OSAS in women which may in part explain the gender differences in sleep apnea associated symptoms.     

Screening for obstructive sleep apnea in patients presenting for snoring surgery

Excessive mortality is associated with obstructive sleep apnea (OSA). Therefore it is important to diagnose OSA in patients presenting for snoring surgery. A prospective study was performed to develop screening models to detect OSA compared with universal polysomnography for sensitivity and cost. Multivariate analysis of 150 consecutive patients was based on clinical data, questionnaire data, and polysomnography. Two screening models obtained 100% sensitivity and reduced the need for polysomnograms. Cost savings of screening based on clinical data was projected to be $35 to $80 per patient using reported prevalence rates of OSA among snorers. A screening model for OSA using clinical data alone is more cost-effective than one that combines these data with pulse oximetry data, but savings over universal polysomnography were modest.     

Nonsurgical and surgical management of infants and children with obstructive sleep apnea syndrome

Obstructive sleep apnea (OSA) syndrome in infants and children is one of the more common problems treated by the otorhinolaryngologist-head and neck surgeon. The authors discuss diagnostic studies, nonsurgical and surgical therapies, and perioperative care, including indications for inpatient stay following surgery. Most children are successfully treated for obstructive breathing by adenotonsillectomy. An awareness of the wide range of treatment modalities, with attention to careful postoperative care, should allow for successful management of nearly all children with OSA.     

Pharyngeal critical pressure in patients with obstructive sleep apnea syndrome. Clinical implications

Current evidence suggests that patients with obstructive sleep apnea (OSA) may have greater pharyngeal critical pressure (Pcrit), which reflects the increase in upper airway collapsibility. The contribution of Pcrit to the severity of OSA and to the efficacious continuous positive pressure (nCPAPeff) therapy has never been extensively described and no data are available about the interaction of Pcrit, age, and anthropometric variables. To determine the relationship between Pcrit, severity of the disease, nCPAPeff, and anthropometric variables we measured Pcrit in a group of 106 patients with OSA. Pharyngeal critical pressure was derived from the relationship between maximal inspiratory flow and nasal pressure, Pcrit representing the extrapolated pressure at zero flow. Upper airway resistance (Rus) was determined as the reciprocal of the slope (DeltaPn/DeltaVImax cm H2O/L/s) in the regression equation. In a subgroup of 68 patients, during the diagnostic night, we measured as indices of respiratory effort, the maximal inspiratory esophageal pressure (Pes) at the end of apnea (Pesmax), the overall increase from the minimum to the maximum (DeltaPes), and the rate of increase of Pes during apnea (RPes). As a group, the mean Pcrit was 2.09 +/- 0.1 cm H2O (range, 0 to 4.5) and the mean Rus was 11.1 +/- 0.5 cm H2O/L/s. Although men have greater Pcrit, pharyngeal collapsibility was influenced neither by neck size nor by body mass index (BMI). Although there was a significant relationship between Pcrit and apnea plus hypopnea index (AHI) (r = 0.23, p = 0.02), neck circumference was the stronger predictor of apnea frequency, with Pcrit contributing only to the 3% of the variance. In the group of patients as a whole, a model including AHI, BMI, Rus, and Pcrit explained the 36% of the variance in nCPAPeff, with a greater contribution of AHI, Pcrit accounting for only 3% of the variation. In patients for whom the measure of respiratory effort was obtained, 42% of the variance in nCPAPeff was explained by RPes (33%) and BMI. From these results we conclude that Pcrit alone does not yield a diagnostically accurate estimation of OSA severity and nCPAPeff. Although individual collapsibility may predispose to pharyngeal collapse, upper airway occlusion may require the combination of several factors, including obesity, upper airway structure, and abnormalities in muscle control.     

Pulmonary hemodynamics in the obstructive sleep apnea syndrome. Results in 220 consecutive patients

We have investigated pulmonary hemodynamics in a large series of consecutive, unselected patients with obstructive sleep apnea syndrome (OSAS). The aims of this study were to evaluate the frequency of pulmonary artery hypertension (PH) in OSAS and to analyze, as far as possible, its mechanisms. Two hundred twenty patients were included on the basis of a polysomnographic diagnosis of OSAS (apnea+hypopnea index > 20). PH, defined by a resting mean pulmonary artery mean pressure (PAP) of at least 20 mm Hg, was observed in 37 of 220 patients (17%). Patients with PH differed from the others with regard to pulmonary volumes (vital capacity [VC], FEV1) and the FEV1/VC ratio that were significantly lower (p < 0.001); PaO2 (64.4 +/- 9.3 vs 74.7 +/- 10.1 mm Hg; p < 0.001); PaCO2 (43.8 +/- 5.4 vs 37.6 +/- 3.9 mm Hg; p < 0.001), apnea+hypopnea index (100 +/- 33 vs 74 +/- 32; p < 0.001), and mean nocturnal arterial oxygen saturation (SaO2) (88 +/- 6% vs 94 +/- 2%; p < 0.001). Patients with PH were also more overweight (p < 0.001). Multiple regression analysis showed that 50% of the variance of PAP could be predicted by an equation including PaCO2 (accounting for 32% of the variance), FEV1 (12%), airway resistance (4%), and mean nocturnal SaO2 (2%). In conclusion, PH is observed, in agreement with previous studies, in less than 20% of OSAS patients. PH is strongly linked to the presence of an obstructive (rather than restrictive) ventilatory pattern, hypoxemia, and hypercapnia, and is generally accounted for by an associated obstructive airways disease. In this regard, the severity of OSAS plays only a minor role.     

A cost-effective and rational surgical approach to patients with snoring, upper airway resistance syndrome, or obstructive sleep apnea syndrome

The past decade has seen several innovations in the surgical techniques available for treatment of patients with sleep-disordered breathing. Outpatient techniques such as laser-assisted uvulopalatoplasty (LAUP) and more aggressive procedures designed to address hypopharyngeal and base of tongue obstruction (genioglossus advancement and hyoid myotomy) have been developed and proven successful. We describe the efficacy of LAUP for snoring (72.7%), upper airway resistance syndrome (81.8%), and mild (mean [+/-SD] respiratory disturbance index [RDI] = 12 +/- 8.1) obstructive sleep apnea (41.7%) in 56 patients who underwent 132 LAUP procedures in a 26-month period. Thirty-two patients with more significant obstructive sleep apnea (mean RDI = 41.8 +/- 23.1) underwent multilevel pharyngeal surgery consisting of genioglossus advancement and hyoid myotomy combined with uvulopalatopharyngoplasty. The surgical success rate in this group of patients was 85.7% when commonly accepted criteria were applied. We recommend a stratified surgical approach to patients with sleep-disordered breathing. Progressively worse airway obstruction marked by multilevel pharyngeal collapse and more severe sleep-disordered breathing is treated with incrementally more aggressive surgery addressing multiple areas of the upper airway.     

Anamnestic and polygraphic parameters in obstructive sleep apnea syndrome patients with reduced nasal respiration during the day in comparison with obstructive sleep apnea patients with normal nasal respiration

Nasal obstruction is a predictive factor for snoring and may contribute to the development of an obstructive sleep apnea syndrome (OSAS). The aim of this study was to further evaluate the impact of nasal obstruction in OSAS. Therefore, we investigated 2 groups of OSAS-patients, matched pairs concerning gender, age, and BMI: OSAS-patients with nasal obstruction (N, n = 28), total nasal airflow < 500 ccm/s (referred to 150 pa pressure of difference or unilateral nasal resistance > 1 pa/ccm/s), and 28 OSAS-patients without nasal obstruction (control-group K, total nasal airflow > 700 ccm/s [referred to 150 pa pressure of difference or unilateral nasal resistance > 1 pa/ccm/s]). We performed anterior rhinomanometry, lung-function testing, cardio-respiratory polygraphy, and patients answered a standardized questionnaire. We found the following significant differences: 1) N complained more often (n = 17) about dyspnea at night than K (n = 7, p < 0.05, Chi2-test). 2) N had a higher apnea index (20.4 +/- 19.0/h) than K (9.6 +/- 10.0/h, p < 0.05, Student's t-test). There were, however, no significant differences concerning lung function, number of nocturnal hypopneas, nocturnal SaO2 and heart rate. Our results underline the importance of nasal ventilation in the pathogenesis of OSAS. At least in moderate cases of OSAS a therapy of nasal obstruction might be of success in order to abolish nCPAP-therapy or might reduce nasal problems during nCPAP-therapy and thus ameliorate patient's therapy compliance.     

Hyoid myotomy and suspension for obstructive sleep apnea syndrome

Hyoid bone suspension with inferior myotomy has been shown to be a successful technique in the treatment of obstructive sleep apnea. However, little mention is made in the literature concerning the details of the surgical procedure. Anatomic details have been given even less attention. This article addresses the regional anatomy, surgical technique, and materials for suspension of the hyoid bone, along with newer modifications of the procedure. Potential risks and complications are also discussed.     

The relationship between the severity of sleep apnea syndrome and 24-h blood pressure values in patients with obstructive sleep apnea

Analysis of the nucleotide sequence in the 5' flanking region of bacteriophage T4 gene 25 revealed three potential Shine and Dalgarno sequences, SD1, SD2 and SD3, with a spacing of 8, 17 and 27 nucleotides from the initiation codon of this gene, respectively. Results of our experiments in the bacteriophage T7 expression system clearly demonstrate that the SD3 sequence is required for efficient expression of gene 25. We propose the existence of a stem-loop structure that includes SD1 and SD2 sequences and brings the SD3 sequence to a favourable spacing with the initiation codon of gene 25. Since the predicted secondary structure in the translational initiation region of gene 25 is relatively unstable and the SD3 sequence, GAGG, is more typical than the SD1 sequence, GAG, we suggest that this structure could control the level of gene expression.     

Neuropsychological functioning and determinants of morning alertness in patients with obstructive sleep apnea syndrome

Neuropsychological functioning is reported to be impaired in patients suffering from obstructive sleep apnea syndrome (OSAS). This syndrome is characterized by nocturnal respiratory disturbances, blood oxygen desaturations, sleep fragmentation, and excessive daytime sleepiness. Opinions are divided concerning the exact relationship between the observed cognitive deficits, nocturnal hypoxia, sleep disruption, and impaired daytime alertness. In the present study, morning neuropsychological function of 26 moderate to severe middle-aged sleep apneics is compared to that of 22 primary insomniacs. There were no performance differences on a range of neuropsychological tests among the two patient groups. In addition, the data suggest that morning alertness impairment, which is closely associated with a lack of slow wave sleep (SWS) and rapid eye movement (REM) sleep, is of major importance in inducing poorer cognitive performance in patients with moderate to severe sleep apnea.     

Upper airway muscles and physiopathology of obstructive sleep apnea syndrome

Upper airway dilator muscle generate inspiratory pressure that balances subatmospheric pharyngeal pressure gene-rated by diaphragmatic contraction leading to reduce upper airway patency. Neural control of upper airway dilator muscles involve several categories of receptors such as vagal pulmonary receptors, upper airway mecanoreceptors, baroreceptors, chemoreceptors. Upper airway resistances increase during sleep and upper airway inspiratory muscle activity decrease especially during bursts of rapid eye movements in REM sleep. Sleep-related upper airway obstruction occurs when upper airway dilator pressure does not balance subatmospheric pharyngeal pressure. Several variables are involved in the pathophysiology of obstructive apneas such as upper airway anatomical factors, structural muscular dysfunction, changes in neural drive.     

Treatment of obstructive sleep apnea syndrome by rapid maxillary expansion

The precise role of maxillary constriction in the pathophysiology of obstructive sleep apnea (OSA) is unclear. However, it is known that subjects with maxillary constriction have increased nasal resistance and resultant mouth-breathing, features typically seen in OSA patients. Maxillary constriction is also associated with alterations in tongue posture which could result in retroglossal airway narrowing, another feature of OSA. Rapid maxillary expansion (RME) is an orthodontic treatment for maxillary constriction which increases the width of the maxilla and reduces nasal resistance. The aim of this pilot study was to investigate the effect of rapid maxillary expansion in OSA. We studied 10 young adults (8 male, 2 female, mean age 27 +/- 2 [sem] years) with mild to moderate OSA (apnea/hypopnea index-AHI 19 +/- 4 and minimum SaO2 89 +/- 1%), and evidence of maxillary constriction on orthodontic evaluation. All patients underwent treatment with RME, six cases requiring elective surgical assistance. Polysomnography was repeated at the completion of treatment. Nine of the 10 patients reported improvements in snoring and hypersomnolence. There was a significant reduction in AHI (19 +/- 4 vs 7 +/- 4, p < 0.05) in the entire group. In seven patients, the AHI returned to normal (i.e., = < 5); only one patient showed no improvement. These preliminary data suggest that RME may be a useful treatment alternative for selected patients with OSA.     

Neurostimulation for obstructive sleep apnea: investigations

Neurostimulation of the upper airway muscles (accessory muscles of respiration) was accomplished in anesthetized dogs and sleeping humans by electrical stimulation of the hypoglossal nerves. Such stimulations relieved partial airway obstructions in dogs. They also aborted (shortened) obstructive sleep apnea events in humans who suffer with obstructive sleep apnea syndrome. In one subject, stimulations delivered in advance of apneic events (by automatic cycling) prevented apneas. Neurostimulation for obstructive sleep apnea may be an important concept for future research and development.     

Cephalometric assessment in obstructive sleep apnea

It is reported that some specific craniofacial characteristics are associated with obstructive sleep apnea syndrome (OSAS). To test this finding, the present study developed and assessed the feasibility of a craniofacial index score (CIS) in differentiating patients with OSAS from habitual snorers. Anthropometric measurements and lateral head radiographs were obtained on 24 male and 4 female patients with OSAS who had physician-diagnosed OSAS (respiratory disturbance index (RDI) >20), and 25 male and 5 female habitual snorers (RDI <20). Thirteen cephalometric and four anthropometric measure- ments were used in a discriminant model to construct the CIS. The model was able to correctly classify 82.1% of the OSAS group and 86.7% of the snoring group. In addition, variables that were related to the soft tissues, hyoid bone to mandibular plane, Body Mass Index, and soft palate length had the highest predictive value. These findings indicate that a CIS constructed from cephalometric and anthropometric measurements can be used to identify subjects with and without OSAS.     

Chemical control of breathing in patients with obstructive sleep apnea

The authors have studied chemical control of breathing in 37 normocapnic patients with OSA. These patients had increased apnea-hypopnea index (AHI = 51 +/- 22), obesity (BMI = 32.4 +/- 5.6 kg/m2) and normal lung function tests. Control group consisted of 20 healthy subjects with normal weight (BMI = 23.1 +/- 2.4 kg/m2). Respiratory responses (ventilatory and P0.1) to hypercapnic and hypoxic stimulation during rebreathing tests were measured with computerized methods. The obtained results in OSA patients were compared with the data of the control group. The results exceeding mean values of the control group above 1.64 SD were recognized as hyperreactive responses. The majority e.g. 26 patients (OSA-N) had normal respiratory responses during hypercapnic stimulation. delta V/delta PCO2 = 16.8 +/- 4.5 L/min/kPa, P0.1/delta PCO2 = 3.5 +/- 2.4 cm H2O/kPa/. In remaining 11 patients (OSA-H) respiratory responses were significantly increased delta V/delta PCO2 = 39.1 +/- 18.8 L/min/kPa, P0.1/delta PCO2 = 8.6 +/- 3.9 cm H20/kPa). During isocapnic hypoxic stimulation majority e.g. 25 patients (OSA-H) had significantly increased respiratory responses delta V/delta SaO2 = 3.28 +/- 1.63 L/min/%, delta P0.1/delta SaO2 = 0.54 +/- 0.43 cm H2O/%/. In remaining 12 patients (OSA-N) respiratory responses were within normal limits delta V/SaO2 = 1.2 +/- 0.28 L/min/%, delta P0.1/ delta SaO2 = 0.21 +/- 0.07 cm H2O/%/. The above results indicated, that majority OSA patients (67.5%) had increased ventilatory and P0.1 responses to hypoxic stimulation. Among them also 11 patients had increased respiratory responses to hypercapnia. It seems, that increased respiratory responses to hypoxic stimulus in OSA patients are symptoms of protective reaction to hypoxaemia occurring during repetitive sleep apnoea and reveals increased neuro-muscular output.