The impact of nasal obstruction on obstructive sleep apnea syndrome

Summary Objective   Nasal obstruction is a predictive factor for snoring and may contribute to the development of obstructive sleep apnea syndrome (OSAS) by causing a higher negative intrapharyngeal pressure during inspiration. This may lead to obstructive apneas and hypopneas in predisposed people. The aim of this study was to further enrole the impact of nasal obstruction on OSAS. Patients and Methods   We investigated two groups of OSAS patients, matched pairs concerning gender, age, and BMI: OSAS patients with nasal obstruction (N, n = 28): total nasal airflow < 500 ml/s* (*referred to 150 pa pressure of difference; anterior rhinomanometry) or unilateral nasal resistance > 1 pa/ml/s*; and 28 OSAS patients without nasal obstruction (control-group C ; total nasal airflow > 700 ml/l/s*). All patients had routine examination including a standardized questionnaire, examination by an otorhinolaryngologist, anterior rhinomanometry, skin prick-testing with 18 common allergens, lung function testing, and full polysomnography. Results   We found the following significant differences: 1) In N more patients (n = 17) complained about nocturnal dyspnea than in C (n = 7; p < 0,05, (Chi²-test); 2) N had a higher apnea index (20,4 ± 19,0/h) than C (9,6 ± 10,0/h; p < 0,05, student's t -test). There were, however, no significant differences concerning lung function, skin prick test, otorhinolaryngologistical results, sleep architecture, number of hypopneas, nocturnal S_aO₂, heart rate, and level of CPAP pressure. Conclusion   Hence, beside pathophysiologically interesting effects increased nasal resistance has no clinically relevant importance in patients with OSAS.     

Functional nasal surgery in the treatment of obstructive sleep apnea

The study included 22 males with significant decrease in nasal patency, at age of 44+/-7 yrs with body mass index 28.9+/-3.8 kg/m2, diagnosed with obstructive sleep apnea syndrome (OSAS) by polysomnography. All patients underwent functional, corrective nasal surgery. In one patient an infection in the wound occurred. Postoperatively 19 (86%) patients reported significant subjective improvement. With regard to polysomnography, one patient was cured and in another one a decrease of AHI to more than 50% of baseline was found. In 6 (27.3%) patients AHI rose from 33.2+/-13 to 53.6+/-21.2. Conclusion: Nasal surgery in OSAS shows limited effectiveness. Because of multilevel decrease in airway patency, some of the patients may need a step-wise approach to surgical treatment.     

Effects of nasal surgery and tonsillectomy on sleep apnea

Twenty-three adults with moderate to severe sleep apnea syndrome (SAS) and positive ENT obstructive findings were treated by either tonsillectomy or by submucosal resection (SMR). Fourteen of the 23 patients (60.8%), 5 of the 7 who underwent tonsillectomy and 9 of the 16 treated by SMR, reported on a clinical improvement in the quality of their nocturnal sleep and diurnal hypersomnolence. Post-treatment polyhypnographic recordings in all responding patients disclosed significantly less apneas and waking within sleep.     

Influence of nasal resistance on oral appliance treatment outcome in obstructive sleep apnea

It has been recognized that nasal airway resistance (NAR) is elevated in patients with OSA. However, little is known regarding the influence of nasal resistance on mandibular advancement splint (MAS) treatment outcome in OSA patient. We hypothesized that nasal resistance differs between MAS responders and nonresponders and therefore may influence treatment outcome. Thirty-eight patients with known OSA underwent polysomnography while wearing a custom-made MAS. Treatment outcome was defined as follows: Responders (R) > or =50% reduction in AHI, and Nonresponders (NR) as <50% reduction in AHI. NAR was measured using posterior rhinomanometry in both sitting and supine positions, with and without MAS. The mean AHI in 26 responders was significantly reduced from 29.0 +/- 2.9/h to 6.7 +/- 1.2/h; P < 0.01). In 12 nonresponders there was no significant change in AHI (23.9 +/- 3.0/h vs 22.0 +/- 4.3/h; P=ns). Baseline NAR was significantly lower in responders in the sitting position compared to nonresponders (6.5 +/- 0.5 vs 9.4 +/- 1.0 cm H2O; P < 0.01). There was no significant change in NAR (from baseline) with MAS in either response group while in the sitting position, but in the supine position NAR increased significantly with MAS in the nonresponder group (11.8 +/- 1.5 vs. 13.8 +/- 1.6 cm H2O/L/s; P < 0.01). Logistic regression analysis revealed that NAR and BMI were the most important predictive factors for MAS treatment outcome. These data suggest that higher levels of NAR may negatively impact on treatment outcome with MAS.     

Predictors of obstructive sleep apnea

Background

A patient’s condition, such as obesity, plays a key role in the pathophysiology of obstructive sleep apnea (OSA). This study focuses on morphometric data that might be associated with the apnea–hypopnea index (AHI) and could therefore be used to predict OSA in order to better select patients for cardiorespiratory polysomnography (PSG).

Methods

Data of 110 patients with suspected OSA in the sleep center outpatient department were analyzed retrospectively. The data included morphometric measurements such as neck, waist, and hip circumference; weight; body size; age; and Epworth Sleepiness Scale (ESS). The results of the patients’ overnight polygraphy, the AHI, completed the data.

Results

Neck and waist circumference can predict the AHI (p < 0.01). Power of prediction was higher for both factors among male (p < 0.01) compared to female patients (p = 0.05). In the case of neck circumference, the threshold value is 40 cm. Neck circumferences of more than 40 cm are strongly associated with a higher AHI (p < 0.001).

Conclusion

It was possible to confirm the roles of waist and neck circumference as important parameters for a prediction model. Nevertheless, these parameters alone are not precise enough to completely neglect factors such as anatomic morphology in order to predict OSA and its severity.

     

Nocturnal nasal obstruction is frequent and reduces sleep quality in patients with obstructive sleep apnea

The prevalence and consequences of nasal obstruction in untreated obstructive sleep apnea patients are not known. The study objectives were to investigate the frequency of subjective and objective nasal obstruction in untreated sleep apnea patients and the associations with sleep and quality of life. Patients in the Icelandic Sleep Apnea Cohort were subjected to a type 3 sleep study, answered questionnaires and had their nasal dimensions measured by acoustic rhinometry. In total, 810 patients participated (including 153 females), aged 54.5 ± 10.6 years [mean ± standard deviation (SD)] with an apnea/hypopnea index 44.7 ± 20.7 h^?1. Nocturnal nasal obstruction (greater than or equal to three times per week) was reported by 35% of the patients. These patients had smaller nasal dimensions measured by the minimum cross‐sectional area within the smaller nasal valve (0.42 ± 0.17 versus 0.45 ± 0.16 cm², P = 0.013), reported more daytime sleepiness (Epworth Sleepiness Scale score 12.5 ± 4.9 versus 10.8 ± 5.0; P < 0.001) and slightly lower mental quality of life than patients without nocturnal nasal obstruction. Nocturnal nasal obstruction is reported in one‐third of the sleep apnea patients and they are more likely to suffer from daytime sleepiness and slightly reduced quality of life than other sleep apnea patients.     

Diagnosis of obstructive sleep apnea

The diagnosis of obstructive sleep apnea is frequently made by taking a meticulous history coupled with a high index of suspicion. Snoring and hypersomnolence are clinical features common to individuals with sleep apnea. Since snoring is said to be a “disease of listeners,” it is not uncommon that bed partners report an increased incidence of depression and marital displeasure. It is for this reason that the spouse or bed partner should be interviewed, since the patient may not be aware of any sleeping problems. Physicians should also be alert to complaints of excessive daytime somnolence, because studies have shown that patients with obstructive sleep apnea are at increased risk for automobile crashes (41, 42). It has been estimated that approx 58, 000 motor vehicle accidents involving people with sleep apnea will occur in the US each yr (43). By proper diagnosis and treatment, the physician is in a unique position to prevent at least some of the automobile accidents that result from falling asleep while driving. Polysomnography is the only definitive way to obtain a diagnosis of sleep apnea. This allows the physician not only to diagnosis the disorder, but also helps in the evaluation of the severity of the syndrome and selection of therapy. An ENT evaluation is also important in ruling out anatomic disorders that can cause upper airway obstruction. Certain factors, such as alcohol and sedative ingestion, may aggravate the condition in a person predisposed to sleep apnea, and subtle changes, such as unexplained hypertension, polycythemia, and cor pulmona!e, should lead one to investigate the possibility of sleep apnea as the etiology.     

Effect of doxapram on obstructive sleep apnea

To determine whether treatment with a respiratory stimulant, doxapram hydrochloride, would improve obstructive sleep apnea, we administered the drug to four patients with this disease. Subjects were given a bolus of doxapram, 0.5 mg X kg-1 lean body mass, followed by a 1 mg X min-1 infusion throughout the night on one night and placebo another night. Doxapram produced improvement in the average oxyhemoglobin desaturation during apneic and hypopneic episodes and decreased average apnea length, but did not change the average number of oxyhemoglobin desaturations per hour of sleep or sleep efficiency. We conclude that doxapram, when administered at levels known to increase ventilatory drive, does not decrease the number of disordered breathing events during sleep but does cause termination of these events at higher levels of oxyhemoglobin saturation.     

Benefit of nasal CPAP in obstructive sleep apnea is due to positive pharyngeal pressure

The purpose of this study was to determine if the mechanism of nasal continuous positive airway pressure's (CPAP's) effectiveness is to act as a pneumatic splint or to increase functional residual capacity (FRC) and consequently, upper airway caliber. Four subjects with obstructive sleep apnea underwent 3 nights of polysomnography: night 1, control; night 2, nasal CPAP; night 3, external subatmospheric pressure (ESAP). ESAP, a negative pressure body suit, increases FRC. We measured the changes in FRC with nasal CPAP and ESAP using the weighted spirometer technique. The dose used for the ESAP night was the dose that produced the same FRC as the subject's prescribed nasal CPAP dose. The mean number of arousals and the respiratory events index were higher on ESAP and control nights. Less severe oxygen desaturation occurred during non-rapid-eye-movement sleep on the nasal CPAP and ESAP nights. These preliminary results show that increasing FRC alone does not account for the effectiveness of nasal CPAP, and splinting of the collapsible upper airway is necessary.     

Nitric oxide and obstructive sleep apnea

Obstructive sleep apnea is a common disease, affecting 16% of the working age population. Although sleep apnea has a well-established connection to daytime sleepiness presumably mediated through repetitive sleep disruption, some other consequences are less well understood. Clinical, epidemiological, and physiological investigations have demonstrated a connection between sleep apnea and daytime hypertension. The elevation of arterial pressure is evident during waking, when patients are not hypoxic, and is mediated by sustained sympathoexcitation and by altered peripheral vascular reactivity. This review summarizes data suggesting that both the sympathoexcitation and the altered vascular reactivity are, at least in part, a consequence of reduced expression of nitric oxide synthase, in neural tissue and in endothelium. Reduced nitric oxide generation in central and peripheral sites of sympathoregulation and in endothelium together may, in part, explain the elevations in waking pressures observed in sleep apnea patients.     

Genioglossus fatigue in obstructive sleep apnea

Obstructive sleep apnea (OSA) is a prevalent disorder that may cause cardiovascular disease and fatal traffic accidents but the pathophysiology remains incompletely understood. Increased fatigability of the genioglossus (the principal upper airway dilator muscle) might be important in OSA pathophysiology but the existing literature is uncertain. We hypothesized that the genioglossus in OSA subjects would fatigue more than in controls. In 9 OSA subjects and 9 controls during wakefulness we measured maximum voluntary tongue protrusion force (Tpmax). Using surface electromyography arrays we measured the rate of decline in muscle fiber conduction velocity (MFCV) during an isometric fatiguing contraction at 30% Tpmax. The rate of decline in MFCV provides an objective means of quantifying localized muscle fatigue. Linear regression analysis of individual subject data demonstrated a significantly greater decrease in MFCV in OSA subjects compared to control subjects (29.2 ± 20.8% [mean ± SD] versus 11.2 ± 20.8%; p=0.04). These data support increased fatigability of the genioglossus muscle in OSA subjects which may be important in the pathophysiology of OSA.     

Classifying obstructive sleep apnea using smartphones

Obstructive sleep apnea (OSA) is a serious sleep disorder which is characterized by frequent obstruction of the upper airway, often resulting in oxygen desaturation. The serious negative impact of OSA on human health makes monitoring and diagnosing it a necessity. Currently, polysomnography is considered the gold standard for diagnosing OSA, which requires an expensive attended overnight stay at a hospital with considerable wiring between the human body and the system. In this paper, we implement a reliable, comfortable, inexpensive, and easily available portable device that allows users to apply the OSA test at home without the need for attended overnight tests. The design takes advantage of a smatrphone’s built-in sensors, pervasiveness, computational capabilities, and user-friendly interface to screen OSA. We use three main sensors to extract physiological signals from patients which are (1) an oximeter to measure the oxygen level, (2) a microphone to record the respiratory effort, and (3) an accelerometer to detect the body’s movement. Finally, we examine our system’s ability to screen the disease as compared to the gold standard by testing it on 15 samples. The results showed that 100% of patients were correctly identified as having the disease, and 85.7% of patients were correctly identified as not having the disease. These preliminary results demonstrate the effectiveness of the developed system when compared to the gold standard and emphasize the important role of smartphones in healthcare.     

Palatopharyngoplasty and obstructive sleep apnea syndrome

Thirty-five patients diagnosed with obstructive sleep apnea syndrome (OSAS) underwent palatopharyngoplasty (PPP) after an objective evaluation. They were all monitored polygraphically after surgery. The group's postsurgical results were positive, with significant improvement in the apnea-hypopnea index (A + H index) and oxygen desaturation. However, patients with hypopharyngeal or mandibular problems or massive obesity had poor postsurgical results. As no subject has been followed for longer than two years, the long-term prognosis for this surgical approach is unknown.     

Cognitive impairment in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterised by repetitive cessation or reduction of airflow due to upper airway obstructions. These respiratory events lead to chronic sleep fragmentation and intermittent hypoxemia. Several studies have shown that OSA is associated with daytime sleepiness and cognitive dysfunctions, characterized by impairments of attention, episodic memory, working memory, and executive functions. This paper reviews the cognitive profile of adults with OSA and discusses the relative role of altered sleep and hypoxemia in the aetiology of these cognitive deficits. Markers of cognitive dysfunctions such as those measured with waking electroencephalography and neuroimaging are also presented. The effects of continuous positive airway pressure (CPAP) on cognitive functioning and the possibility of permanent brain damage associated with OSA are also discussed. Finally, this paper reviews the evidence suggesting that OSA is a risk factor for developing mild cognitive impairment and dementia in the aging population and stresses the importance of its early diagnosis and treatment.