Simple predictors of uvulopalatopharyngoplasty outcome in the treatment of obstructive sleep apnea

STUDY OBJECTIVE

Our objective was to determine whether baseline polysomnography, cephalometry, and anthropometry data could predict uvulopalatopharyngoplasty (UPPP) success or failure.

DESIGN

We retrospectively reviewed polysomnography, cephalometry, and anthropometry data from patients who underwent UPPP for obstructive sleep apnea (OSA).

SETTING

A university medical center.

PATIENTS

OSA was diagnosed by polysomnography in 46 patients who underwent UPPP surgery for their sleep disorder.

INTERVENTIONS

UPPP surgery with/or without tonsillectomy.

MEASUREMENTS AND RESULTS

The mean patient age was 43 years, and the mean body mass index was 32.5 kg/m(2). The mean presurgical apnea-hypopnea index (AHI) was 45, and the mean baseline nadir oxygen saturation was 81%. Successful surgery was defined as a reduction in AHI to < 10 or to < 20 with a 50% reduction from the patient's baseline AHI. Of the 46 patients, 16 were successfully treated and 30 did not respond to surgical treatment. A mandibular-hyoid distance (MP-H) > 20 mm was found to be significantly (p = 0.05) predictive of failure of UPPP. When stepwise regression analysis was performed utilizing postsurgical AHI as the dependent variable and presurgical AHI, age, body mass index, baseline nadir O(2) saturation, and five cephalometric measurements as independent variables, MP-H distance significantly (r = 0.524; p = 0.01) correlated positively with postsurgical AHI. The distance between the superior point of a line-constructed plane of the sphenoidale (parallel to Frankfort horizontal) and a point at the intersection of the palatal plane perpendicular to the hyoid correlated negatively with postsurgical AHI (r = 0.586; p = 0.05). By creating a logistic model of this data, an MP-H distance < 21 mm, an angle created by point A to the nasion to point B < 3 degrees, and the presence of a baseline AHI < 38 enhanced the predictability of UPPP success.

CONCLUSIONS

The presence of a baseline AHI < 38 and an MP-H < or = 20 mm, and the absence of retrognathia are predictors of improvement after UPPP. Based on these findings, we would advocate the continued evaluation of cephalometric measurements and careful consideration of surgical treatment options for OSA.

The role of the primary care physician in recognizing obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disorder among middle-aged adults. However, OSA is a recently described disorder for which most primary care physicians do not have formal training. The primary objectives of this article are to evaluate what percentage of patients referred by primary care physicians for sleep studies had OSA; to characterize the clinical features of these patients and compare them with our known OSA population; and to determine whether primary care physicians asked key questions contained in a work sheet to make the diagnosis of OSA.

METHODS

A retrospective chart review at a hospital-based sleep center that is accredited to evaluate all sleep disorders, not just OSA. The health maintenance organization is a staff model one.

PATIENTS

Sixty-nine patients who were referred for a sleep study by a health maintenance organization internist or family practitioner between June 1, 1994, and May 30, 1995.

RESULTS

Ninety-six percent of the 68 patients referred for polysomnography had OSA. Most were very symptomatic and obese. These 68 patients represent 0.13% of the primary care patient panel. In addition, most of the patients were referred by a few physicians; 6 (11%) of the 55 physicians ordered 33% of the 68 studies.

CONCLUSIONS

Primary care physicians did recognize obese patients with prominent symptoms of sleep apnea. However, only a small percentage of their patient panel was referred, suggesting that this condition is still underdiagnosed. This seems particularly true as most of the sleep studies were ordered by a small group of physicians. Future work incorporating educational interventions is necessary to improve detection and treatment of OSA.

Oral appliances in the treatment of snoring and sleep apnea

Oral appliances have been developed that are effective in snoring patients and in patients with mild to moderate sleep apnea. This article reviews the types of appliances that are available, their possible modes of action, and their efficacy. In addition, the clinician is provided with guidelines on how to choose the appropriate patient for this therapy.

Enuresis and obstructive sleep apnea in adults

Adult enuresis is an unusual symptom of obstructive sleep apnea (OSA). Although it is described as a classic symptom of childhood OSA, enuresis is encountered infrequently in adult sleep medicine. Five adults with enuresis associated with sleep apnea presented to our Sleep Disorders Center. In all five cases, the onset of enuresis was associated with the progression of sleep apnea symptoms. In each case, the enuresis resolved with treatment with nasal continuous positive airway pressure. Current medical literature on the postulated mechanisms of nocturia and enuresis in sleep apnea is reviewed. Based on the experience of the authors and review of the medical literature, one may conclude that severe OSA may lead to new-onset enuresis in adults and that effective treatment of OSA is associated with resolution of enuresis.

Identification and modification of environmental noise in an ICU setting

STUDY OBJECTIVES

Noise levels in the hospital setting are exceedingly high, especially in the ICU environment. We set out to determine what caused the noises producing sound peaks > or = 80 A-weighted decibels (dBA) in our ICU settings, and attempted to reduce the number of sound peaks > or = 80 dBA through a behavior modification program.

DESIGN

The study was divided into two separate phases: noise identification and a trial of behavior modification. During the noise identification phase we simultaneously recorded sound peaks and the loudest noise heard subjectively by one observer in the medical ICU (MICU) and the respiratory ICU (RICU). During the behavior modification phase of the study we implemented a behavior modification program, geared toward noise reduction, in all of the MICU staff. Sound levels were monitored before and at the end of the behavior modification trial.

SETTING

The MICU and RICU of a 720-bed teaching hospital in Providence, RI.

PARTICIPANTS

All ICU staff during the study period.

INTERVENTIONS

Once the noises that were determined to be amenable to behavior modification were identified, a behavior modification program was conducted during a 3-week period in our MICU. Baseline and post-behavior modification noise recordings were compared in 6-h intervals after sites were matched by number of patients in a room and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores.

MEASUREMENTS AND RESULTS

We identified several causes of sound peaks > or = 80 dBA amenable to behavior modification; television and talking accounted for 49%. We also significantly reduced the 24-h mean peak noise level (p=0.0001), as well as the mean peak noise level (p=0.0001) and the number of sound peaks > or = 80 dBA (p=0.0001) in all 6-h blocks except for the 12 AM to 6 AM period.

CONCLUSIONS

We conclude that many of the noises causing sound peaks > or =80 dBA are amenable to behavior modification and that it is possible to reduce the noise levels in an ICU setting significantly through a program of behavior modification.

The efficacy of oral appliances in the treatment of persistent sleep apnea after uvulopalatopharyngoplasty

Twenty-four patients who failed uvulopalatopharyngoplasty (UPPP) for obstructive sleep apnea (OSA) had an adjustable oral (Herbst) appliance made to treat the persistent apnea. Six patients discontinued the device prior to sleep evaluation. Eighteen patients had polysomnographic evaluations at baseline, post-UPPP, and with the Herbst appliance in place. The apnea-hypopnea index baseline (AHI) and arterial oxygen saturation (SaO2) nadir were 42.3+/-6.1 and 83.6+/-1.8%, respectively. There was no significant change in either parameter with surgery. With the oral appliance, the AHI fell to 15.3+/-4.4 (p < or = 0.01) and the SaO2 nadir increased to 87.9+/-1.2% (p < or = 0.05). Ten of the patients had control of the OSA with the Herbst appliance with a fall in the AHI to < 10. There were, in addition, two partial responders as defined by an AHI of <20 and a >50% fall in AHI compared with baseline and post-UPPP values. All but one of the responders and partial responders had complete resolution of subjective symptoms of daytime sleepiness with the appliance. An adjustable oral appliance appears to be an effective mode of therapy to control OSA after an unsuccessful UPPP.

Oral appliances in the treatment of snoring and sleep apnea

Oral appliances have been developed that are effective in snoring patients and in patients with mild to moderate sleep apnea. This article reviews the types of appliances that are available, their possible modes of action, and their efficacy. In addition, the clinician is provided with guidelines on how to choose the appropriate patient for this therapy.

Unusual complication of nasal CPAP: subcutaneous emphysema following facial trauma

Subcutaneous emphysema is an unusual complication of nasal continuous positive airway pressure (CPAP). We report a case of a 58-year-old man who fell and sustained mild facial trauma to the left side of his head. After using CPAP the following night, he developed diffuse subcutaneous emphysema of his face and left neck. He discontinued CPAP, and his symptoms improved. The potential mechanisms of this patient's subcutaneous emphysema and the prior reports of this complication following facial trauma or dental procedure without use of CPAP are reviewed. Although there are case reports of bacterial meningitis and pneumocephalus following use of nasal CPAP, we are not aware of any prior reports of subcutaneous emphysema following use of CPAP. In light of our experience and the above related case reports, we would suggest nasal CPAP be withheld temporarily in the setting of acute facial trauma.

Air leaking through the mouth during nocturnal nasal ventilation: effect on sleep quality

Air leaking through the mouth has been reported in kyphoscoliotic patients receiving nasal ventilation via volume-limited ventilators. This study accessed the frequency of occurrence and effect on sleep quality of air leaking through the mouth during nocturnal nasal ventilation in patients with chest wall and neuromuscular disease using pressure-limited ventilation. Overnight and daytime polysomnography was performed in six stable experienced users of nocturnal nasal noninvasive positive-pressure ventilation (NPPV) who had chronic respiratory failure due to neuromuscular disease or chest wall deformity. All patients used the BiPAP S/T-D ventilatory support system (Respironics, Inc., Murrysville, PA). Measures included sleep scoring, leak quantitation, diaphragm and submental electromyograms (EMGs), and tidal and leak volumes. All patients had air leaking through the mouth for the majority of sleep. Sleep quality was diminished because of poor sleep efficiency and reduced percentages of slow-wave and rapid eye movement (REM) sleep. Air leaking through the mouth was associated with frequent arousals during stages 1 and 2 and REM sleep that contributed to sleep fragmentation, but arousals were infrequent during slow-wave sleep. Despite prevalent leaking, oxygenation was well maintained in all but one patient. Patients used a-combination of passive and active mechanisms to control air leaking. Although nasal ventilation improves nocturnal hypoventilation and symptoms in patients with restrictive thoracic disorders, air leaking through the mouth is very common during use. The leaking is associated with frequent arousals during lighter stages of sleep that interfere with progression to deeper stages, compromising sleep quality. Portable pressure-limited ventilators compensate for leaks, maintaining ventilation and oxygenation, but further studies are needed to determine which interfaces and ventilator techniques best control air leaking and optimize sleep quality.

Effects of menopause and nasal occlusion on breathing during sleep

Prevalence of sleep-disordered breathing (SDB) is reported to increase in menopausal women. We examined response to a nocturnal respiratory challenge (nasal occlusion) during overnight polysomnography in 31 women (45 to 55 yr). Thirteen were premenopausal, four perimenopausal, and 14 postmenopausal by history and hormonal assay. Nasal occlusion increased the apnea hypopnea index (AHI) (occlusion mean = 6.6 +/- 8.0 versus baseline mean = 1.6 +/- 2.6, p < 0.01) and arousal index (occlusion mean = 35.1 +/- 20.1 versus baseline mean = 20.7 +/- 11.6, p < 0.001), but did not change the oxygen saturation nadir in those with respiratory events (occlusion mean = 91.8 +/- 4.2 versus baseline mean = 92.0 +/- 11.6). Menopausal groups did not differ on AHI, arousal index, or oxygen saturation nadir in either condition. Key variables were compared between occlusion responders (n = 11) and nonresponders (n = 20). Responders and nonresponders were not distinguished by age, menopausal status, nor several cephalometric or anthropometric variables. Body mass index (31.1 +/- 8.5 versus 24.3 +/- 3.4, p < 0.003), neck circumference (34.0 +/- 2.5 versus 32.5 +/- 1.7 cm, p < 0.05), and mandibular-hyoid distance (18.5 +/- 3.8 versus 14.5 +/- 5.7 mm, p < 0.05) were greater in responders. These findings suggest hormonal factors may be less important than weight and facial morphology in midlife development of SDB in women.

Environmental noise as a cause of sleep disruption in an intermediate respiratory care unit

Our laboratory previously reported continuously monitored peak sound levels in several areas at Rhode Island Hospital. The number of sound peaks greater than 80 A-weighted decibels (dBA) was found to be high in the intensive and intermediate respiratory care unit (IRCU) areas, even at night. Environmental noise of this magnitude is potentially sleep-disruptive. Therefore, we hypothesized that nocturnal peak sound levels of > or = 80 dBA would be associated with an increase in EEG arousals from sleep in patients in the IRCU. Six patients underwent sleep monitoring while environmental peak sound levels were continuously recorded. Each 8-hour period (2200 to 0600 hours) was broken down into 30-minute segments. If there were 10 minutes or more of wakefulness in a segment, that segment was dropped from further analysis. Of the remaining 61 segments, there was a very strong correlation (r = 0.57, p = 0.0001) between the number of sound peaks of > or = 80 dBA and arousals from sleep. These 61 periods were then classified as quiet, moderately loud, and very loud based on the number of sound peaks (< or = 5, 6-15, and > 15, respectively). Analysis of variance revealed a significant difference between the number of arousals (p = 0.001) in quiet periods and that in very loud periods. We conclude that environmental noise may be an important cause of sleep disruption in the IRCU.

Sleep disorders and outpatient treatment of patients with pulmonary disease

Patients with chronic obstructive pulmonary disease, kyphoscoliosis, and neuromuscular disorders frequently desaturate in rapid eye movement sleep. This can lead to polycythemia, pulmonary hypertension, and respiratory failure. In addition, these patients as well as those with asthma may have unsuspected coexistent obstructive sleep apnea. The detection of hypoventilation, oxygen desaturation, and obstructive sleep apnea may lead to more effective treatment of these patients.

Sleep, breathing, and cephalometrics in older children and young adults. Part II -- Response to nasal occlusion

STUDY OBJECTIVES

We postulated that nasal occlusion would provide a challenge enabling us to assess factors predisposing development of sleep apnea in older children/adolescents and young adults. Factors of interest included sex, age, body mass index (BMI), tonsillar hypertrophy, and cephalometric measurements.

DESIGN

Sleep and breathing variables were examined and compared for four groups of subjects between one baseline night and one night of nasal occlusion in a sleep research laboratory.

SUBJECTS

Healthy, normal boys (n=23, mean age=13.3+/-2.1 years), girls (n=22, mean age=13.8+/-1.8 years), men (n=23, mean age=22.2+/-1.5 years), and women (n=24, mean age=22.4+/-1.8 years) were studied.

MEASUREMENTS AND RESULTS

The following sleep and sleep-related breathing measures showed significant increases in all four groups from baseline to occlusion: percentage of stage 1, number of transient arousals, transient arousal index, apnea index, respiratory disturbance index (RDI), and mean apnea length. No significant relationships were found between occlusion-night RDI and tonsillar size, cephalometric variables, or BMI, either singly or in combination.

CONCLUSIONS

Subjects' responses to nasal occlusion varied: most demonstrated a minimal and clinically insignificant increase in RDI; few showed a marked increase in RDI. Significant increases of sleep fragmentation -- even in the absence of frankly disturbed breathing -- indicate that nasal occlusion may secondarily affect waking function if prolonged over a series of nights.

Sleep, breathing, and cephalometrics in older children and young adults. Part I -- Normative values

STUDY OBJECTIVES

Aims were (1) to provide normative values for sleep and sleep-related breathing variables and physical features (cephalometrics, body mass index [BMI], and tonsillar size) in older children/adolescents and young adults, (2) to describe sex and age group differences, and (3) to evaluate relationships between physical features and sleep-related breathing variables.

DESIGN

Standard polysomnographic variables describing sleep and breathing were measured during a single night. Cephalometric measures were obtained from a standing lateral skull radiograph.

SUBJECTS

Normal, healthy boys (n=23; mean age=13.3+/-2.1 years), girls (n=22; mean age =13.8+/-1.8 years), men (n=23; mean age=22.2+/-1.5 years), and women (n=24; mean age=22.4+/-1.8 years) with BMI less than 27 were evaluated.

RESULTS

Sleep variables showed age group and sex differences consistent with published norms. Slow-wave sleep and rapid eye movement (REM) latency declined with age; transient arousals increased with age. Sleep-related breathing variables showed few changes related to age group or sex; small but statistically significant sex differences were found for arterial oxygen saturation nadir (lower in male subjects) and respiration disturbance index in non-REM sleep (greater in male subjects). Differences in cephalometric measures largely reflected normal growth and expected sex differences. No significant relationships between sleep-related breathing variables and physical findings were observed.

CONCLUSIONS

These data provide well-controlled normative values for sleep, breathing, and cephalometrics in a group of normal older children, adolescents, and young adults. The data provide useful reference points for patients of these ages in whom sleep apnea is suspected, particularly since such clinical studies are normally based on first-night polysomnography. Furthermore, these values represent developmentally appropriate grouping of the data.

Body fat distribution and sleep apnea severity in women

The contribution of body fat distribution to sleep-disordered breathing in women has not been examined in detail (to our knowledge). Fifty women under 65 years of age were diagnosed as having obstructive sleep apnea (OSA) by all-night polysomnography in a 6-month period. Twenty-five women underwent body fat measurements of skin folds and circumferences. The 12 premenopausal and 13 postmenopausal women did not differ in regard to apnea hypopnea index (AHI), SaO2 nadir, body mass index (BMI), or anthropometric measurements. The AHI for these 25 patients was related to the severity of obesity assessed by triceps and subscapular skin folds, the sum of the skin folds, waist circumference, and BMI. The SaO2 nadir correlated with triceps and subscapular skin folds, the sum of the skin folds, and neck skin fold. Clinical features of this same group of 25 women were then compared with those of 45 men with OSA previously described by our laboratory. The women, despite similar age, had less severe OSA than the men (AHI of 34.4 +/- 5.4 vs 51.1 +/- 4.9, p < 0.05). Despite similar BMIs and waist circumference, the men had evidence of a greater degree of upper body obesity with a larger subscapular skin fold thickness, waist-hip ratio, and neck circumference. In addition, for a given degree of upper-body obesity, men had more severe sleep apnea. These findings may explain, at least in part, the greater severity of OSA in the men.

A dental and medical approach to sleep apnea. Part I: An overview of sleep apnea

Over the last decade there has been increasing evidence that obstructive sleep apnea is a common and potentially serious medical problem. Until recently the condition was primarily dealt with by pulmonary, sleep, and ENT physicians. With the development of the oral mandibular advancement devices for the treatment of sleep apnea, dentists have played an increasing role in the treatment of the condition. This series of articles will review the pathophysiology, clinical manifestations, diagnostic strategies and treatment options for this condition.

Efficacy of a Herbst mandibular advancement device in obstructive sleep apnea

Treatment options for obstructive sleep apnea (OSA) may involve potential side effects or discomfort; nasal continuous positive airway pressure (CPAP) may not be tolerated by 25% of patients. We therefore sought to determine the efficacy of mandibular advancement as a treatment for OSA, and to investigate whether clinical and radiographic parameters can predict the response to this treatment. Sixteen male and 3 female subjects with documented OSA who had failed or been unable to tolerate nasal CPAP underwent baseline polysomnography and cephalometry, and were then fitted with a removable Herbst appliance to achieve forward mandibular advancement during sleep. All subjects then underwent a second cephalometric evaluation and polysomnography with the appliance in place. Fourteen of 15 subjects demonstrated significant improvement in the degree of OSA, based on the apnea-hypopnia index (AHI) (34.7 +/- 5.3 to 12.9 +/- 2.4 events/h, p < 0.002). Comparison of pre- and posttreatment cephalometric values revealed no significant change in the posterior airway space (PAS) despite a reduction in mean AHI. There was a significant decrease in the mandible-hyoid distance (MP-H) with treatment for the group as a whole. When the study population was evaluated on the basis of a successful response to mandibular advancement (posttreatment AHI < 10), the baseline MP-H was found to be significantly shorter in the responders than in nonresponders. MP-H after mandibular advancement was likewise shorter in responders than in nonresponders. In addition, the soft palate length (PNS-P) showed a significantly greater shortening in responders after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adverse environmental conditions in the respiratory and medical ICU settings

Sleep deprivation and fragmentation occurring in the hospital setting may have a negative impact on the respiratory system by decreasing respiratory muscle function and ventilatory response to CO2. Sleep deprivation in a patient with respiratory failure may, therefore, impair recovery and weaning from mechanical ventilation. We postulate that light, sound, and interruption levels in a weaning unit are major factors resulting in sleep disorders and possibly circadian rhythm disruption. As an initial test of this hypothesis, we sampled interruption levels and continuously monitored light and sound levels for a minimum of seven consecutive days in a medical ICU, a multiple bed respiratory care unit (RCU) room, a single-bed RCU room, and a private room. Light levels in all areas maintained a day-night rhythm, with peak levels dependent on window orientation and shading. Peak sound levels were extremely high in all areas representing values significantly higher than those recommended by the Environmental Protection Agency as acceptable for a hospital environment. The number of sound peaks greater than 80 decibels, which may result in sleep arousals, was especially high in the intensive and respiratory care areas, but did show a day-night rhythm in all settings. Patient interruptions tended to be erratic, leaving little time for condensed sleep. We conclude that the potential for environmentally induced sleep disruption is high in all areas, but especially high in the intensive and respiratory care areas where the negative consequences may be the most severe.

Sleep-disordered breathing and behavior in three risk groups: preliminary findings from parental reports

Sleep-related breathing disorders may cause excessive daytime sleepiness, cognitive impairment, and behavior problems in children and adolescents. Adenotonsillar enlargement (AT) is known to be a significant risk factor for these disorders, which have also been reported in several patients with Down syndrome (DS). Children with attention deficit disorder/hyperactivity (ADD) show behavior problems that may be related to disturbed nocturnal sleep in some. To evaluate the relationships among these disorders and symptoms, parents of 29 school-aged children with AT, 70 with DS and 48 of their siblings (DS-SIB), and 21 with ADD completed a 20-item screening questionnaire covering nocturnal sleep symptoms and daytime behavior problems. Nocturnal symptoms of sleep-related breathing disorders--snoring, breathing pauses during sleep--were reported more commonly by parents of AT and DS children. However, parents of two of the ADD children reported significant signs of sleep-related breathing disorders. Daytime behavior problems were more common in ADD and AT than in the DS group. Bedwetting reports did not distinguish groups. Direct comparisons of DS and DS-SIB groups showed that more DS were mouth breathers, snored, stopped breathing at night, and were sleepy in the daytime. These findings underscore the importance of obtaining a history of nocturnal sleep from parents of children with AT and DS, as well as those with disrupted daytime behavior.

Sleep-related eating disorder as a cause of obstructive sleep apnea

A patient with obesity resulting from sleep-related eating disorder demonstrated signs and symptoms of obstructive sleep apnea (OSA). Incarceration restricted access to food during the night, leading to weight loss and clinical improvement. Release from prison allowed recurrence of unrestricted sleep-eating, recurrent obesity, and documented OSA. Successful treatment of sleep-related eating disorder can result in improvement in coexisting OSA.

Adiposity and cardiovascular risk factors in men with obstructive sleep apnea

STUDY OBJECTIVE

To assess anthropometric characteristics of patients with obstructive sleep apnea (OSA) and their relationship to cardiovascular risk factors (dyslipidemia, hypertension, glucose intolerance) and severity of breathing abnormalities during sleep.

DESIGN

Case series.

SETTING

Referral-based sleep disorder center serving Rhode Island and Southeastern Massachusetts.

PATIENTS

Forty-five men, 26 to 65 years old, with OSA diagnosed by clinical and polysomnographic criteria.

RESULTS

By national health survey criteria, 51 percent of patients were in the upper fifth percentile for weight, whereas 91 to 98 percent were in the upper fifth percentile for skinfold thicknesses (triceps, subscapular, triceps plus subscapular). Severe upper body obesity, as defined by a waist-hip ratio (WHR) greater than or equal to 1.00, was present in 51 percent of the patients. The WHR, however, did not correlate significantly with the severity of respiratory disturbances during sleep. The patients had higher prevalences of hypertension and impaired glucose tolerance than expected, but normal prevalences of hypercholesterolemia, low high-density lipoprotein cholesterol, and overt diabetes mellitus. Skinfold thicknesses correlated more closely with the severity of OSA than did body mass index (BMI) or neck circumference.

CONCLUSION

Men with OSA have a marked excess of body fat that is not always reflected in measurements of body weight or BMI. Also, upper body obesity, hypertension, and impaired glucose tolerance occur more frequently than expected in this population. Severe adiposity may not only promote development of the respiratory abnormalities of OSA, but also may contribute directly to the increased cardiovascular risk associated with OSA.

One negative polysomnogram does not exclude obstructive sleep apnea

Night-to-night variability of apneas on overnight polymnography exists in patients with documented obstructive sleep apnea (OSA). In this study, we evaluated the possibility that this variability may be severe enough to miss the diagnosis of OSA in patients clinically at risk for the disease. We prospectively studied 11 patients who were deemed on clinical grounds to have probable OSA, but had a negative result on overnight polysomnography. Six of the 11 patients were found to have a positive second study with a significant rise in the apnea/hypopnea index (AHI) from 3.1 +/- 1.0 to 19.8 +/- 4.7 (mean +/- SEM, p < 0.01). The cause of the negative first study in these patients is unclear, but it does not seem related to risk factor pattern, sleep architecture, or test interval. The change in AHI was not found to be rapid eye movement (REM)-dependent. This study demonstrates that a negative first-night study is insufficient to exclude OSA in patients with one or more clinical markers of the disease.

Treatment of nocturnal asthma

Extensive work has been done over the past decade to determine the best drug regimen for the treatment of nocturnal asthma. Much of the work has been directed at the evaluation of theophylline preparations and beta sympathomimetic agents. With a better understanding of the mechanisms causing nocturnal asthma, future therapeutic advances will be targeted at the underlying pathophysiological causes of the disorder. This article will review current treatment modalities, including those shown to have some effect as well as those that have no benefit.

Sleep-disordered breathing in patients with Duchenne muscular dystrophy using negative pressure ventilators

We studied the occurrence of nocturnal disordered breathing events and O2 desaturations in 12 patients with late-stage Duchenne muscular dystrophy (DMD) using negative pressure ventilators. We also assessed the effects of O2 supplementation and nasal continuous positive airway pressure (CPAP) on disordered breathing events in selected patients and examined sleep quality in a small subgroup. Average age was 23 + 2 years and FVC was 293 + 33 ml. Eleven of the 12 patients had more than five disordered breathing events per hour during nocturnal monitoring, and the lowest O2 saturation was < 85 percent in nine patients. Nasal O2 (2 L/min) during negative pressure ventilation in four patients did not alter the frequency of disordered breathing events, prolonged the mean and maximum durations of events, and failed to eliminate severe O2 desaturations in two patients. Nasal CPAP was used in two patients during negative pressure ventilation and completely eliminated disordered breathing events in both. Overnight polysomnography during negative pressure ventilation in three patients demonstrated frequent awakenings that fell in frequency following elective tracheostomy in two patients and use of nasal CPAP in one. We conclude that negative pressure ventilation in patients with late-stage DMD is associated with frequent disordered breathing events and severe O2 desaturations in many patients. Concomitant use of O2 supplementation may prolong the events, but a switch to positive pressure ventilation or addition of nasal CPAP is effective therapy.

The association of normal-pressure hydrocephalus with obstructive sleep apnea

This report describes a 70-year-old man with obstructive sleep apnea who deteriorated rapidly when nasal continuous positive airway pressure was begun. The patient was found to have normal-pressure hydrocephalus, which was possibly exacerbated by the nasal continuous positive airway pressure. A review of the literature indicates several significant associations between apnea, normal-pressure hydrocephalus, and increased intracranial pressure and suggests that the association of obstructive sleep apnea and hydrocephalus might not be rare. Implications for diagnosis and treatment are discussed.

Studies in the genetics of obstructive sleep apnea. Familial aggregation of symptoms associated with sleep-related breathing disturbances

Previous studies of single families have suggested that familial factors may be important in the pathogenesis of obstructive sleep apnea. In this report, the role of inheritance in obstructive sleep apnea was assessed by quantitating the degree of familial clustering of symptoms associated with sleep-related breathing disorders. In total, 272 subjects from 29 families identified through an index case with obstructive sleep apnea and 21 control families with no relative known to have sleep apnea were studied with questionnaires that ascertained health status and symptoms. The unadjusted odds ratios of habitual or disruptive snoring, breathing pauses, and excessive day-time sleepiness in subjects with a single relative with the same symptom were 1.40 to 1.53 (p less than 0.05). Odds ratios increased progressively for subjects with increasing numbers of symptomatic relatives). Adjustment for body mass index, age, and gender modestly reduced these odds ratios to 1.33 to 1.42. These data suggest a significant familial aggregation of symptoms associated with sleep-disordered breathing that appears independent of familial similarities in weight.

Nocturnal positive-pressure ventilation via nasal mask in patients with severe chronic obstructive pulmonary disease

Intermittent positive pressure ventilation administered nocturnally via a nasal mask has been associated with improvements in pulmonary function and symptoms in patients with restrictive ventilatory disorders. We hypothesized that nocturnal nasal ventilation (NNV) would bring about similar improvements in patients with severe chronic obstructive pulmonary disease (COPD). The study used a randomized, crossover design, with subjects undergoing NNV or "standard care" for sequential 3-month periods. Of 23 patients with obstructive lung disease and a FEV1 less than 1 L who were initially enrolled, 4 were excluded because of obstructive sleep apnea prior to randomization. Among the remaining 19 patients, 7 withdrew because of intolerance of the nose mask, 5 were withdrawn because of intercurrent illnesses, and 7 completed both arms of the protocol. These latter 7 patients used the ventilator for an average of 6.7 h/night, and 3 of the 7 had partial relief of dyspnea during ventilator use. However, in comparison with studies performed upon initiation or after the standard care arm of the study, studies performed after 3 months of NNV revealed no improvements in pulmonary function, respiratory muscle strength, gas exchange, exercise endurance, sleep efficiency, quality or oxygenation, or dyspnea ratings. The only improvements observed were in neuropsychological function, possibly related to a placebo effect or another unknown mechanism. Despite the small sample size, our study indicates that NNV is not well tolerated by and brings about minimal improvements in stable outpatients with severe COPD.

Measurement of sleep-related breathing disturbances in epidemiologic studies. Assessment of the validity and reproducibility of a portable monitoring device

The feasibility and reliability of measuring sleep-related breathing disorders with a portable monitor (PM) were assessed in a heterogeneous population, consisting of 31 patients recruited from a sleep laboratory and pulmonary disease clinic, 16 participants in a genetic-epidemiologic study of sleep apnea, and four volunteers with no specific sleep complaints. The validity of measurements made by the PM was assessed with comparisons of respiratory parameters made with the PM to those determined with in-hospital polysomnography (PSG) (25 studies). Reproducibility was assessed in 29 subjects who underwent in-home monitoring on two occasions. There was a high level of agreement between the number of respiratory events (apneas or hypopneas) per hour of estimated sleep (respiratory disturbance index, RDI) recorded with the PM and PSG and log-transformed (r = 0.96). Using a RDI of greater than or equal to 10 to define "abnormality," 20 of the 21 subjects who would have been classified as abnormal with PSG were classified similarly with use of the PM. A similar high level of agreement was demonstrated for the log-transformed RDI determined with replicate in-home studies (r = 0.94). No evidence of a "first-night effect" for the RDI was suggested in studies performed with the PM; ie, RDI was 18.4 +/- 27.7 and 17.4 +/- 25.7 (mean +/- SD) for first and second night studies, respectively (p = 0.21). A second compared with an initial study with the PM would have resulted in reclassification of abnormality based on an RDI of greater than or equal to 10 in one subject. These findings suggest that measurement of the RDI with in-home monitoring provides a valid and highly reproducible index for assessment of sleep-related respiratory disturbances for use in epidemiologic studies of general populations.

Daytime hypertension in obstructive sleep apnea. Prevalence and contributing risk factors

We examined the prevalence of daytime hypertension in a modern sample of patients with obstructive sleep apnea (OSA) and assessed the relative risk factors contributing to the development of hypertension in this disorder. Daytime hypertension was present in 92 (45 percent) of 206 male and female patients with OSA. Stepwise logistic regression revealed that only age and body mass index (BMI) were predictors of hypertension in this population. A subsample of 152 male patients with OSA was then compared to 904 men identified from a geographically and ethnically similar general population. When one controlled for age and BMI, the prevalence of hypertension in the two groups was the same except for those aged 25 to 44 years who were markedly obese (BMI greater than 31 kg/m2). In this group, 47 percent of the patients with OSA were hypertensive vs 26 percent of control subjects (p less than 0.05). Our data suggest that the high prevalence of hypertension in OSA is primarily related to age and the excess obesity seen in these patients. In morbidly obese young patients with OSA, factors directly related to OSA may also be contributing to the development of hypertension. With increasing age, other competitive risks may obscure any independent effect that OSA may exert.

Causes and consequences of blood pressure alterations in obstructive sleep apnea

The obstructive sleep apnea (OSA) syndrome has been considered to be a cause of both transient blood pressure elevations during sleep and sustained hypertension during the awake state. The purpose of this review was to examine critically the existing literature regarding (1) the blood pressure alterations associated with OSA, (2) causal mechanisms relating specific blood pressure alterations to OSA, and (3) potential consequences of the systemic circulatory abnormalities associated with OSA. Particular attention was directed at studies that assessed the prevalence of OSA in patients with hypertension and that examined the effects on blood pressure of treatment of OSA. We conclude that patients with OSA have abnormal sleep blood pressure patterns, manifested most frequently by apnea-associated blood pressure elevations. Confounding factors such as obesity and antihypertensive drug therapy, and conflicting evidence regarding changes in daytime blood pressure after therapy for OSA, make it premature to conclude that OSA and daytime hypertension are directly associated. Circumstantial evidence suggests that the blood pressure alterations that occur during sleep could contribute to the high cardiovascular morbidity in patients with OSA. Further research into the relationship between OSA and hypertension should improve the future care of patients with these conditions and enhance our understanding of cardiopulmonary pathophysiology.

Sleepwalking precipitated by treatment of sleep apnea with nasal CPAP

A 33-year-old man with a long history of snoring, observed apneic episodes, and excessive daytime sleepiness, underwent all-night polysomnography, which demonstrated severe obstructive sleep apnea. During the nasal CPAP trial, two episodes of sleepwalking were observed during a period of delta sleep rebound.

Sleep apnea and panic attacks

A survey of 301 sleep apnea patients demonstrated that obstructive sleep apnea may cause nocturnal panic attack symptoms. Sleep apnea should be considered in the differential diagnosis of nocturnal panic disorder.

A family study of sleep apnea. Anatomic and physiologic interactions

The distribution of symptoms, physiologic responses, and upper airway structure in members of one family with three generations of subjects with sleep apnea (SA) is reported. Questionnaire data were obtained from ten family members (ages 7 to 66 years), overnight sleep studies were performed in nine subjects, and ventilatory responses to hyperoxic hypercapnia and to eucapnic hypoxia and cephalometry were obtained in five subjects. All ten family members reported habitual snoring or nighttime snorting/gasping; five of ten family members also reported excessive daytime sleepiness. All studied subjects except for a pregnant woman had greater than ten apneas/hypopneas per hour. Ventilatory responses to hypoxia were markedly reduced in all five subjects studied (less than or equal to 0.51 L/min/SaO2); hypercapnic responses were reduced in three of five subjects (less than or equal to 0.61 L/min/mm Hg CO2). No subject was morbidly obese (body mass index less than 29 kg/m2) or demonstrated retrognathia. The posterior airway space was reduced in three subjects, and the mandibular to hyoid distance was increased in four subjects. The two subjects with the longest soft palates and the most inferiorly displaced hyoids had the most severe sleep disorder. Sleep apnea was present, albeit less profound, in the one subject with normal anatomy who had an abnormal hypoxic ventilatory response. The distribution of these physiologic and anatomic measurements in this family provides further support for a genetic basis for SA, and suggests that the disorder may occur as a result of interactions between ventilatory control abnormalities and anatomic risk factors.

Changes in airway resistance following nasal provocation

Controversy exists on whether stimulation of the nasal mucosa results in reflex bronchoconstriction. To address shortcomings in previous experimental design, we performed double-blind randomized nasal challenges in asthmatic patients with allergic rhinitis and in controls. Using pledgets containing 10-microliters aliquots of 0.9% saline or increasing concentrations of methacholine or histamine, we were able to increase nasal resistance significantly in both groups. Only methacholine caused an increase in lower airway resistance, and this could be blunted by premedication of the nasal mucosa with phenylephrine. This suggests that the effect on lower airway resistance was due to systemic absorption. Our study does not support the existence of a nasobronchial reflex from mechanical alteration of the nasal mucosa.

Depression as a manifestation of obstructive sleep apnea: reversal with nasal continuous positive airway pressure

Fifty-five patients with obstructive sleep apnea each completed a Zung Self-Rating Depression Scale (SDS), Twenty-five patients (45%) had SDS scores greater than or equal to 50, consistent with depression. The SDS scores did not correlate with age, the number of respiratory events per hour sleep, antihypertensive medication, or the oxygen saturation baseline or nadir. The group with SDS scores of 50 or greater, however, had 68.0 +/- 8.8 respiratory events per hour compared with 47.9 +/- 4.7 in the group with SDS scores under 50 (p less than .05). Nineteen patients who were treated with nasal continuous positive airway pressure completed a follow-up SDS Inventory. After treatment, the SDS scores fell from 60.5 +/- 1.9 to 44.4 +/- 2.6 (p less than .001) in the 11 patients with baseline elevated scores. The authors conclude that obstructive sleep apnea can produce prominent symptoms of depression that appear to be related to the severity of the underlying apnea; furthermore, treatment of obstructive sleep apnea may result in alleviation of these symptoms in certain patients.

Massive epistaxis from nasal CPAP therapy

A 75-year-old man with obstructive sleep apnea and secondary right heart failure was started on nasal CPAP therapy. Shortly thereafter he experienced massive life-threatening epistaxis requiring nasal packing and hospitalization. The epistaxis was thought to be due to the drying effect of nasal CPAP.

Rapid development of cor pulmonale following acute tonsillitis in adults

We describe two adult patients in whom acute tonsillitis resulted in the rapid development of cor pulmonale in the absence of clinically evident upper airway obstruction or diffuse obstructive airway disease. Both patients had developed symptoms of sleep apnea and all-night polysomnography confirmed the presence of severe obstructive sleep apnea. These cases emphasize the potentially severe cardiovascular consequences of acute tonsillar hypertrophy in the obese adult patient.

Changes in compartmental ventilation in association with eye movements during REM sleep

The effect of phasic eye movement activity on ventilation during rapid-eye-movement (REM) sleep was studied in seven healthy young adults by use of the respiratory inductive plethysmograph. Mean ventilation (VE) and ventilatory components during REM sleep were not significantly different from that seen in either stages 1-2 or 3-4 sleep. The percent of rib cage contribution to ventilation in REM sleep, 29.3 +/- 5.1%, was reduced compared with 54.4 +/- 5.8% in stage 1-2 and 52.2 +/- 4.3% in stage 3-4 sleep (P less than 0.005). When one separated breaths by the degree of associated phasic eye movement activity, it became apparent that breathing during REM sleep is very heterogeneous. Increasing eye movement activity was associated with inhibition of ventilation with a reduction in VE from 5.1 +/- 0.3 to 3.8 +/- 0.3 l/min. Tidal volume and frequency both fell, whereas inspiratory duration was unchanged. Compartmental ventilation was also affected, with the fall in the rib cage contribution from 37.8 +/- 6.4 to 15.3 +/- 5.6%. Chest wall and abdominal movement became more asynchronous as phasic-eye-movement activity increased and frank paradoxical breathing was seen.

A home monitoring system for nasal CPAP

A compact portable sensing system (PSS) was developed for home monitoring of patients with obstructive sleep apnea treated with nasal continuous positive-airway pressure (CPAP). The system consisted of a solid-state pressure sensor connected with plastic tubing to the side port of the nasal CPAP mask, a power supply, and a strip chart recorder. The device was validated against standard polysomnography in ten patients with obstructive sleep apnea undergoing overnight nasal CPAP trials. A total of 397 apneas and hypopneas were observed in the ten patients. The PSS device detected 386 events (sensitivity, 97.2 percent). In addition, there were 29 false positive events noted by the device (positive predictive value, 93 percent). The device was then tested at home in 23 patients on nasal CPAP. Eight of these patients had persistent apneas requiring adjustment of their CPAP pressure. The PSS device allowed for accurate reevaluation of nasal CPAP settings in the patient's home without necessitating expensive, time-consuming in-hospital laboratory polysomnographic studies.

Spectral analysis of ventilation in elderly subjects awake and asleep

We studied the periodicities of ventilation in elderly subjects using digital comb filtering. Two groups of subjects were studied, those with and without sleep apnea. Measurements were made in wakefulness, stage 1-2 sleep, and where possible in stage 3-4 sleep. For each of the digital filters we calculated the average power of the oscillatory output. To compare subject groups we first specifically determined the average power in the filter with the maximum output. The mean of this measurement was greater in elderly subjects with apnea compared with those without apnea, both during wakefulness and stage 1-2 sleep. In both groups of subjects the cycle time of the major ventilatory oscillations was on the order of 40-60 s. There was no difference in this cycle time between the two groups of subjects in wakefulness or stage 1-2 sleep. Thus, whereas similar oscillatory processes occur in subjects with and without apnea, it is the magnitude of the oscillation that differs between the two groups. These conclusions are supported by analysis of the output of individual filters of the digital comb filter. In both groups, stage 1-2 sleep produced significantly increased oscillations in ventilation. Both in wakefulness and stage 1-2 sleep, significantly greater periodicities occurred in the apneic compared with the nonapneic group. In the few subjects who had sufficient data in stage 3-4 sleep for spectral analysis, ventilatory oscillations were virtually absent in this state. Our data suggest that subjects who develop apnea during sleep have an increased propensity for periodic breathing even while awake.