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PubMed1998

Altered cardiovascular variability in obstructive sleep apnea.

BACKGROUND: Altered cardiovascular variability is a prognostic indicator for cardiovascular events. Patients with obstructive sleep apnea (OSA) are at an increased risk for cardiovascular disease. We tested the hypothesis that OSA is accompanied by alterations in cardiovascular variability, even in the absence of overt cardiovascular disease. METHODS AND RESULTS: Spectral analysis of variability of muscle sympathetic nerve activity, RR interval, and blood pressure were obtained during undisturbed supine rest in 15 patients with moderate-to-severe OSA, 18 patients with mild OSA, and 16 healthy control subjects in whom sleep disordered breathing was excluded by complete overnight polysomnography. Patients with OSA were newly diagnosed, never treated for OSA, and free of any other known diseases. Patients with moderate-to-severe OSA had shorter RR intervals (793+/-27 ms) and increased sympathetic burst frequency (49+/-4 bursts/min) compared with control subjects (947+/-42 ms; 24+/-3 bursts/min; P=0.008 and P<0.001, respectively). In these patients, total variance of RR was reduced (P=0.01) and spectral analysis of RR variability showed an increase in low frequency normalized units, a decrease in high frequency normalized units, and an increase in the ratio of low to high frequency (all P<0.05). Even though blood pressure was similar to that of the control subjects, blood pressure variance in patients with moderate-to-severe OSA was more than double the variance in control subjects (P=0.01). Patients with mild OSA also had a reduction in RR variance (P=0.02) in the absence of any significant difference in absolute RR interval. For all patients with OSA, linear regression showed a positive correlation (r=0.40; P=0.02) between sleep apnea severity and blood pressure variance. CONCLUSIONS: Cardiovascular variability is altered in patients with OSA. This alteration is evident even in the absence of hypertension, heart failure, or other disease states and may be linked to the severity of OSA. Abnormalities in cardiovascular variability may be implicated in the subsequent development of overt cardiovascular disease in patients with OSA.

Adult↗

PubMed1997

Obstructive sleep apnea and abnormal P300 latency topography.

This study was conducted to evaluate cognitive abnormalities in obstructive sleep apnea (OSA) using cognitive evoked potentials (P300), and to clarify if such cognitive dysfunction is related to the OSA itself or to the hypersomnolence in OSA. Subjects were administered a polysomnogram, auditory and visual P300 testing using 31 scalp electrodes, and the multiple sleep latency test. There were 40 normal subjects ages 26 to 75. Of 143 consecutive OSA patients ages 26 to 75, 56 had severe OSA (Respiratory Disturbance Index or RDI 40-80/h sleep) with objective somnolence (Mean Sleep Latency < 5 min). Thirty-three had severe OSA without objective somnolence. Fifty-four had profound OSA (RDI > 80/h sleep) with or without objective somnolence. The normals and the three OSA groups did not differ in age. Patients with profound OSA or with severe OSA without somnolence had longer visual P300 latency than normals. The groups also differed in visual P300 latency topography. OSA patients had significantly longer latencies frontally than normals. Thus, OSA, even in the absence of hypersomnolence, is associated with abnormalities in cognitive evoked potentials. Visual P300 latency at frontal electrodes seems to be a neurophysiological index of dysfunction in OSA that is independent of tests of sleepiness.

Adult↗

PubMed1992

The relationship between sleep apnea syndrome and hypothyroidism.

To evaluate the prevalence of obstructive sleep apnea syndrome (OSAS) in patients with hypothyroidism, the prevalence of hypothyroidism in patients with OSAS, the possible factors predisposing to sleep-related breathing disorder in hypothyroid patients, and the effect of thyroid hormone in treating hypothyroidism associated with OSAS, we studied 65 patients with proven OSAS (apnea index [AI] > 5) and 20 hypothyroid patients. All patients were monitored for one overnight sleep study using polysomnography (Grass 78). We found only two (3.1 percent) of 65 OSAS patients had thyroid hypofunction. Of 20 patients with hypothyroidism, two showed moderate to severe OSAS and three had mild OSAS. Patients with both hypothyroidism and OSAS had impaired respiratory drive, but this was corrected by thyroid hormone therapy. Patients with hypothyroidism without OSAS were younger and had a lower percentage of ideal body weight than those with both hypothyroidism and OSAS. All hypothyroid patients were snorers. Thyroid hormone replacement was effective in correcting snoring only after one year of therapy. We conclude the following: (1) an overnight sleep study is not necessary in every case of hypothyroidism; (2) thyroid function studies need not be done routinely for every OSAS patient; (3) thyroid hormone therapy is effective for OSAS but it takes longer to correct the snore than respiratory drive; and (4) age and body weight are related to the development of OSAS.

Adult↗

PubMed2002

Incidence and severity of obstructive sleep apnea following pharyngeal flap surgery in patients with cleft palate.

OBJECTIVE: To investigate the incidence and severity of obstructive sleep apnea (OSA) associated with pharyngeal flap surgery in patients with cleft palate at least 6 months postoperatively and to determine whether age or the flap width had an effect on them. The hypothesis tested in this study was that the severity of OSA associated with pharyngeal flap surgery is greater in children than in adults. SUBJECTS: Ten adults, six men and four women, with a mean age of 28.0 years at pharyngeal flap (adult group). Twenty-eight children, 13 boys and 15 girls, with a mean age of 6.3 years at pharyngeal flap (child group). DESIGN: A prospective analysis. MAIN OUTCOME MEASURES: An overnight polysomnographic study was used to determine the incidence and severity of OSA 6 months after pharyngeal flap. RESULTS: The incidence of OSA following pharyngeal flap was high but not significantly different between these two groups (90% in adults and 93% in children, p = 1.000). When OSA was stratified into different levels of severity according to the values of respiratory disturbance index, there were noticeable differences between these two groups (p =.022). In the adult group, eight patients (89%) had mild OSA and 1 patient (11%) had moderate to severe OSA. In the child group, 11 patients (42%) were found to have mild OSA, and 15 patients (58%) had moderate to severe OSA. No relation was found between the flap width and the incidence (p =.435 in adults and.640 in children) or the severity (p =.325 in adults and.310 in children) of OSA in each group. CONCLUSIONS: Six months following pharyngeal flap surgery, more than 90% of the patients with cleft palate still had OSA. The severity of OSA associated with pharyngeal flap surgery tended to be greater in children than in adults. The flap width was unrelated to the incidence and severity of OSA, no matter in adults or in children.

Adult↗

PubMed2001

Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: a case-control study.

OBJECTIVE: To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (OSAS) undergoing hip replacement or knee replacement compared with control patients undergoing similar operations. Although OSAS is a risk factor for perioperative morbidity, data quantifying the magnitude of the problem in patients undergoing non-upper airway operations are limited. PATIENTS AND METHODS: This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS between January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were using continuous positive airway pressure (CPAP) prior to hospitalization. Matched controls were patients without OSAS undergoing the same operation. Interventions were defined specifically as administration of a particular treatment in the context of each complication, eg, supplemental oxygen, implementation of additional monitoring such as oximetry for hypoxemia, or transfer to the intensive care unit (ICU) for cardiac ischemia concerns. Postoperative complications were assessed for all patients in the different categories and included respiratory events such as hypoxemia, acute hypercapnia, and episodes of delirium. Serious complications were noted separately, including unplanned ICU days, reintubations, and cardiac events. The length of hospital stay was also tabulated. RESULTS: There were 101 patients with the diagnosis of OSAS in this study and 101 matched controls. Thirty-six patients had their joint replacement before OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of the latter 65 patients, only 33 were using CPAP at home preoperatively. Complications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group (P=.001). Serious complications occurred in 24 patients (24%) in the OSAS group compared with 9 patients (9%) in the control group (P=.004). Hospital stay was significantly longer for the OSAS patients at a mean +/- SD of 6.8 +/- 2.8 days compared with 5.1 +/- 4.1 days for the control patients (P<.007). CONCLUSION: Adverse postoperative outcomes occurred at a higher rate in patients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.

Adult↗

PubMed2004

Obstructive sleep apnea and cardiovascular disease.

Obstructive sleep apnea (OSA) is a common medical condition that occurs in approximately 5% to 15% of the population. The pathophysiology of OSA is characterized by repetitive occlusions of the posterior pharynx during sleep that obstruct the airway, followed by oxyhemoglobin desaturation, persistent inspiratory efforts against the occluded airway, and termination by arousal from sleep. Obstructive sleep apnea is associated with daytime sleepiness and fatigue, likely due to fragmented sleep from recurrent arousals. Substantial evidence shows that patients with OSA have an increased incidence of hypertension compared with individuals without OSA and that OSA is a risk factor for the development of hypertension. Recent studies show that OSA may be implicated in stroke and transient ischemic attacks. Obstructive sleep apnea appears to be associated with coronary heart disease, heart failure, and cardiac arrhythmias. Pulmonary hypertension may be associated with OSA, especially in patients with preexisting pulmonary disease. Although the exact cause that links OSA with cardiovascular disease is unknown, there is evidence that OSA is associated with a group of proinflammatory and prothrombotic factors that have been identified to be important in the development of atherosclerosis. Obstructive sleep apnea is associated with increased daytime and nocturnal sympathetic activity. Autonomic abnormalities seen in patients with OSA include increased resting heart rate, decreased R-R interval variability, and increased blood pressure variability. Both atherosclerosis and OSA are associated with endothelial dysfunction, increased C-reactive protein, interleukin 6, fibrinogen, and plasminogen activator inhibitor, and reduced fibrinolytic activity. Obstructive sleep apnea has been associated with enhanced platelet activity and aggregation. Leukocyte adhesion and accumulation on endothelial cells are common in both OSA and atherosclerosis. Clinicians should be aware that OSA may be a risk factor for the development of cardiovascular disease.

Arousal↗

PubMed1998

[Severity of obstructive sleep apnea syndrome relates to sleep architecture changes].

OBJECTIVE: To explore how obstructive sleep apnea syndrome (OSAS) affects sleep architecture and if OSAS severity and treatment relate to it. METHOD: A computer-assistant diagnostic system was used for polysomnography(PSG) recording. Respiratory events were scored automatically and corrected manually. Sleep was scored manually according to the standard set by Rechtschaffen. 31 controls and 147 OSAS patients(RDI > or = 5) were defined by PSG. 11 OSAS patients(RDI = 62.5 +/- 20.8) accepted nCPAP therapy. PSG were recorded both before and during nCPAP treatment. RESULT: (1) Compared with controls, OSAS group had increased sleep shift number (120 +/- 71 vs 92 +/- 60, P = 0.0106); (2) The number of slow wave sleep(SWS) (5 +/- 9 vs 8 +/- 8, P = 0.0035) and the ratio of total SWS time over total sleep time(TST) (5% +/- 8% vs 8% +/- 9%, P = 0.0062), were decreased and the rate of SWS deprivation(48% vs 26%, P < 0.05) were increased greatly in OSAS patients; (3) REM were less affected by OSAS than SWS because the ratio of its total time over TST, its onset number and deprivation rate had no significant difference between the two groups; (4) OSAS group had increased number of WASO (wake after sleep onset) (27 +/- 28 vs 19 +/- 18, P = 0.017) but the ratio of total WASO time over total sleep period had no significant difference between the two groups; (5) The ratio of total RWS(rapid wave sleep) time over TST (94 +/- 10 in OSAS group vs 91 +/- 12, P = 0.0136) and total RWS number(88 +/- 54 in OSAS group vs 65 +/- 45, P = 0.0075) were increased in OSAS group; (6) The above parameters were obviously disturbed in OSAS patients with RDI > or = 25 but had almost no change in patients with RDI < 25 compared with controls. (7) nCPAP could improve the above parameters but only number of WASO(no therapy: 34 +/- 20 vs therapy: 23 +/- 22, P = 0.011), shift number (no therapy: 151 +/- 62 vs therapy: 97 +/- 50, P = 0.019) and the ratio of total RWS time over TST (no therapy: 115 +/- 58 vs therapy: 69 +/- 34, P = 0.025) had statistical significance. CONCLUSION: OSAS severity relates to sleep architecture changes. Those had RDI < 25 had no change compared with control group. Sleep architecture changes could be improved by effective nCPAP therapy.

Adult↗

PubMed2005

Chronic liver injury during obstructive sleep apnea.

Patients with obstructive sleep apnea (OSA) are at risk for the development of fatty liver as a result of being overweight. Several data suggest that OSA per se could be a risk factor of liver injury; ischemic hepatitis during OSA has been reported, and OSA is an independent risk factor for insulin resistance. Therefore, we investigated liver damage and potential mechanisms in 163 consecutive nondrinking patients with nocturnal polysomnographic recording for clinical suspicion of OSA. Serum levels of liver enzymes were measured in all patients. Liver biopsy was offered to patients with elevated liver enzymes. Intrahepatic hypoxia was assessed by the expression of vascular endothelial growth factor (VEGF) on liver biopsy specimens. Severe OSA (apnea-hypopnea index [AHI] > 50/hr) was seen in 27% of patients; 52% had moderate OSA (AHI 10-50/hr), and 21% had no OSA. Overall, 20% had elevated liver enzymes. Independent parameters associated with elevated liver enzymes were body mass index (BMI) (OR: 1.13; CI: 1.03-1.2) and severe OSA (OR: 5.9; CI: 1.2-29). Liver biopsy was performed in 18 of 32 patients with elevated liver enzymes and showed steatohepatitis in 12 cases, associated with fibrosis in 7 cases. Patients with severe OSA were more insulin-resistant according to homeostasis model assessment, had higher percentage of steatosis as well as scores of necrosis and fibrosis, despite similar BMI. Hepatic immunostaining used as an indirect marker of hypoxia was not different between patients with or without severe OSA. In conclusion, severe OSA is a risk factor for elevated liver enzymes and steatohepatitis independent of body weight. Promotion of insulin resistance is probably involved. Further studies are needed to determine whether hypoxia contributes directly to liver injury.

Adult↗

PubMed2006

Comparison of right ventricular functions by tissue Doppler imaging in patients with obstructive sleep apnea syndrome with or without hypertension.

OBJECTIVE: To evaluate the right ventricular function in patients with obstructive sleep apnea syndrome (OSAS) independent from systemic hypertension (HT) and to determine the association between OSAS severity and right ventricular dysfunction. METHODS: The study population included 77 consecutive subjects; 20 of these patients had OSAS, 20 of them had HT, but did not have OSAS, 16 patients, who constituted the study group, had both disorders, and 21 subjects without any of these two disorders represented the control group. Right ventricular function was assessed by echocardiography: standard two-dimensional, M-Mode, and conventional Doppler as well as tissue Doppler imaging. None of the patients had a previous history of cardiac disease. The diagnosis of OSAS was based on an apnea- hipopnea index of 5 or higher in polysomnography. RESULTS: Tricuspid inflow velocities and tissue Doppler derived tricuspid annular diastolic velocities were significantly different in the patient groups (OSAS, HT, OSAS + HT) compared to the control group. Tricuspid annular plane systolic excursion (TAPSE) (18.3 +/- 3.2, 18.4 +/- 2.5, 20.1 +/- 2.1, and 20.7 +/- 2.5 mm, respectively, P = 0.024) and peak systolic myocardial velocity at tricuspid lateral annulus (S-vel) (12.2 +/- 1.5, 10.9 +/- 0.9, 11.2 +/- 1.1, and 13.1 +/- 2.1 cm/s, respectively, P < 0.001) were significantly lower in patient groups compared to those of the study group. Tissue Doppler derived myocardial performance index (MPI) of the right ventricle was significantly impaired in the patient groups compared to the control group (0.34 +/- 0.06, 0.44 +/- 0.06, 0.45 +/- 0.07, and 0.41 +/- 0.06, respectively, P < 0.001). With regard to these right ventricular functional parameters, there was no significant difference between OSAS and the other patient groups (HT and OSAS + HT). There were significant correlations both between OSAS severity and the right ventricular functions, and between diastolic and systolic parameters of the right ventricle (r = -0.45, P < 0.05). CONCLUSION: Both right ventricular systolic and diastolic functions are impaired in patients having OSAS with or without HT. Right ventricular MPI was found to be the parameter most closely related with OSAS severity and the right ventricular subclinical dysfunction.

Adult↗

PubMed1999

Sleep Apnea in Moderate-Severe Obese Patients.

Obesity induces multiple physiologic changes at the respiratory and circulatory systems level. A study was developed to identify symptoms and signs able to discriminate subjects at high risk of obstructive sleep apnea (OSA) and to evaluate the presence of OSA in a population of obese patients referred to the Clinical Nutrition Service of the Luigi Sacco Hospital for weight loss therapy. Twenty-seven obese patients (14 males, 13 females) without neurologic, cardiac, and lung diseases were measured for height, weight, neck, waist, and hip circumference; a sample of venous blood was taken for hematological data; and were given a pulmonary function test, hemogasanalysis, and full-night polysomnography. Statistical analysis were performed using paired and unpaired StudentOs t test, PearsonOs chi square, and Spearmann Rank correlation; the significance level was set at p<0.05. The results showed hemotological values in the normal range and pulmonary function findings were not different from predicted, but expiratory reserve volume (ERV), as expected in obese subjects, was significantly reduced (p<0.001). Waist, hip, and neck circumference, and waist/hip ratio were 114 +/-14, 118 +/-12, 44 +/-4, and 0.96 +/-0.4 cm respectively. An apnea-hypopnea index (AHI) cutoff value of <15 was used to classify the patients as suffering from OSA: 15 patients (12 males, 3 females, age in years 55 +/-12, body mass index (BMI) kg/m(2) 37 +/-6, AHI 30 +/-12) were OSA and 12 patients were non OSA (2 males, 10 females, age in years 49 +/-20, BMI kg/m(2) 35 +/-2, AHI 3 +/-2). PaO2 and pH were lower and PaCO2 higher in OSA (p<0.05, p<0.01, p<0.05, respectively). Red blood cells (RBC), Hb, and neck circumference were increased in OSA (p<0.05). In OSA patients, S3%, S4% of total sleep time, SaO2% mean of nadir were reduced (p<0.001), and DEF increased (p<0.0001). In obese patients, AHI was correlated with neck circumference (r = 0.74, p<0.0001) and waist/hip ratio (r = 0.48. p<0.01). DEF was correlated with RBC, Hb, Htc% (r = 0.82, 0.71, 0.66, p<0.001). SaO2;% mean of nadir was significantly related to RBC, Hb, and Htc% (r = 0.44, 0.40, p<0.05, respectively). Our data showed a prevalence of OSA in 55% of the obese patients. A significant correlation exists between RBC, Hb, Htc%, with desaturation events frequency (DEF) and SaO2% of nadir indicating that transient, episodic desaturation during sleep is linked to a moderate increase of RBC and Hb found in obese patients with OSA, in contrast to obese, nonOSA patients. The most important result of the present study was the determination that classical symptoms and signs of OSA, such as male gender, neck circumference, waist/hip ratio, RBC, and Hb at the upper limit of normal, are simple inexpensive screening tools, and useful predictors of sleep-disordered breathing and discriminate the individuals with higher risk of OSA.

Journal Article↗

PubMed2006

Impact of obstructive sleep apnea on clinical and angiographic outcomes following percutaneous coronary intervention in patients with acute coronary syndrome.

There has been growing evidence associating obstructive sleep apnea (OSA) with cardiovascular pathogenesis. We hypothesized that OSA may affect outcomes after percutaneous coronary intervention (PCI) in patients with acute coronary syndrome (ACS). We performed a sleep study in 89 consecutive patients with ACS who were successfully treated with PCI. Patients with an apnea hypopnea index > or =10/hour were considered to have OSA. Co-morbidity of OSA with ACS was found in 51 patients (57%). There were no differences in baseline demographics between patients with and without OSA, except for significantly higher high-sensitivity C-reactive protein levels (0.59 +/- 0.75 vs 0.29 +/- 0.20 mg/dl, p = 0.019) in patients with OSA. Patients were followed for a mean period of 227 days. The incidence of major adverse cardiac events (cardiac death, reinfarction, and target vessel revascularization) was significantly higher in patients with OSA (23.5% vs 5.3%, p = 0.022). By multivariate analysis, the presence of OSA was an independent predictor for major adverse cardiac events (hazard ratio 11.61, 95% confidence interval 2.17 to 62.24, p = 0.004). In addition, quantitative coronary angiography at 6-month follow-up depicted significantly greater late loss (1.28 +/- 0.84 vs 0.69 +/- 0.81 mm, p = 0.003) and a higher binary restenosis rate (36.5% vs 15.4%, p = 0.026) in patients with OSA compared with those without OSA. In conclusion, the present study showed a high prevalence of OSA among patients with ACS. Moreover, OSA appeared to be an independent predictor for clinical and angiographic outcomes after PCI.

Aged↗

PubMed2005

The influence of the oscillation angle and the neck anteversion of the prosthesis on the cup safe-zone that fulfills the criteria for range of motion in total hip replacements. The required oscillation angle for an acceptable cup safe-zone.

A normal hip joint has more than 120 degrees flexion. The reduced range of motion (ROM) of total hip arthroplast leads to frequent prosthetic impingement, subluxation and dislocation. Prosthetic impingement may be more serious for metal-on-metal and ceramic-on-ceramic total hip prosthesis (THP). A larger oscillation angle of THP (OsA) and proper cup and neck positions make a larger theoretical ROM of a patient's artificial hip joint. But what OsA is required and what range of cup positions is kinetically accepted are not clearly understood. A ROM of more than 120 degrees flexion, 45 degrees internal-rotation at 90 degrees flexion, 30 degrees extension and 40 degrees external-rotation was defined as severe criteria for an acceptable ROM. Theoretical cup safe-zones were created that fulfill the severe criteria of ROM for (OsA=110 degrees , 120 degrees , 135 degrees ) by the mathematical formulas. The size of the cup safe-zone mainly depends on the size of the OsA. There is no cup safe-zone for 110 degrees OsA, an extremely small safe-zone for 120 degrees OsA and an acceptable safe-zone for 135 degrees OsA. Each THP has its own OsA, because OsA is the function of head and neck diameter and cup design. More than 135 degrees OsA enlarges the safe-zone of the prosthetic position, so it extends the acceptable range of error that surgeons cannot avoid completely. However, few THPs with more than 135 degrees OsA are currently clinically available. Both surgeons and manufacturers must realize that OsA is as essential as cup and neck orientations for ROM.

Arthroplasty, Replacement, Hip↗

PubMed2004

Severe, but not mild, obstructive sleep apnea syndrome is associated with erectile dysfunction.

OBJECTIVES: To assess the association between obstructive sleep apnea syndrome (OSAS) and erectile dysfunction (ED). OSAS is associated with fatigue and daily dysfunction. We hypothesized that OSA severity will correlate with ED. We also sought to determine the specific features with predictive value for ED in patients with OSAS. METHODS: A total of 209 patients evaluated for potential OSAS were given a sleep questionnaire, a revised International Index of Erectile Function questionnaire (composed of three main topics: sexual satisfaction, erection during intercourse, and morning erection), and then underwent a full-night in-laboratory polysomnography examination. The data were scored blindly. RESULTS: A decrease in erectile function was found in all OSAS groups compared with those without OSAS. However, the only group for whom this reduction was statistically significant (P <0.05) in all ED dimensions was the severe OSAS group (respiratory disturbance index [RDI] greater than 40). Furthermore, the patients complaining of severe ED had the greatest RDI. Stepwise multiple logistic regression analyses revealed that the predicting factors for ED in OSAS patients were age, morning tiredness, and RDI. CONCLUSIONS: Severe OSAS is clearly associated with ED. However, the relationship is very weak in patients with mild or moderate OSAS. The predictive factors for ED in patients with OSAS include age, morning tiredness, and RDI.

Adult↗

PubMed2000

Obstructive sleep apnea and gastroesophageal reflux.

A number of recent studies have described the presence of significant gastroesophageal reflux (GER) in patients with obstructive sleep apnea (OSA). The aims of our studies were to determine the prevalence of this in a controlled population and to investigate the potential for a causal relationship between the two entities by determining whether therapy of OSA altered GER parameters, and vice versa. All patients presenting to our sleep laboratory for screening polysomnography underwent distal esophageal pH monitoring simultaneously with polysomnography. Control subjects were selected if the apnea-hypopnea index (AHI) was <5.0, and patients were selected if AHI was >15.0. Fourteen subjects with OSA undertook a second polysomnographic study including distal esophageal pH monitoring, with nasal continuous positive airway pressure (nCPAP) intervention. Twelve subjects with proven OSA took part in a randomized, placebo-controlled, double-blinded, parallel group study of the effect of antireflux therapy (nizatidine) on OSA parameters. In 63 patients and 41 controls, we found that patients with OSA had significantly more GER events than controls as measured by number of reflux events over 8 hours (115 vs 23; P <0.001), and percent of time spent at pH <4.0 (21.4% vs 3.7%; P <0.001). In patients with proven OSA, 53.4% of GER episodes were temporally related to apneas or hypopneas. Less than half (46.8%) of all apneas were temporally related to acid reflux, and only 43.8% of arousals were related to reflux events. In the therapeutic trials, nCPAP reduced GER parameters in both patients with OSA and without OSA, suggesting a nonspecific effect. Antireflux therapy (nizatidine) reduced arousals but not apnea-hypopnea index in patients with OSA. Patients with OSA have a higher prevalence of GER than matched control subjects. Nasal CPAP reduces GER parameters nonspecifically, and thus the role of OSA in the pathogenesis of GER remains unclear. GER, however is likely to be important in the pathogenesis of arousals, but there is no evidence that it is involved in the pathogenesis of apneas.

Aged↗

PubMed1984

A diagnostic approach to suspected obstructive sleep apnea in children.

Most children with obstructive sleep apnea will benefit from tonsillectomy and adenoidectomy. Although polygraphic monitoring remains the definitive diagnostic technique, we wondered if all children suspected of having OSA require such evaluation. We therefore administered a standardized questionnaire to the parents of 23 children with polygraphically proved OSA related to adenotonsillar hypertrophy, 46 age- and sex-matched normal children, and 23 children subsequently referred because of possible OSA. Significantly increased frequencies of the following symptoms were found in the OSA group compared with the control group: difficulty breathing during sleep, 96% vs 2%; apnea observed by the parents, 78% vs 5%; snoring, 96% vs 9%; restless sleep, 78% vs 23%; chronic rhinorrhea, 61% vs 11%; and mouth breathing when awake, 87% vs 18%. Using discriminant analysis, an OSA score was derived that correctly classified all control subjects and 22 of 23 patients with OSA. Considering the data from all groups, we found that (1) OSA scores greater than 3.5 were highly predictive of OSA requiring adenotonsillectomy; (2) no child with an OSA score less than -1 had OSA; and (3) in children with OSA scores between -1 and 3.5, polygraphic monitoring was required to determine the severity of sleep-related airway obstruction and the need for surgical treatment. Use of the OSA score should decrease the need for polygraphic monitoring and facilitate selection of children for tonsillectomy and adenoidectomy.

Adenoids↗

PubMed2003

Heart rate variability in obstructive sleep apnea: a prospective study and frequency domain analysis.

BACKGROUND: Cyclic variation of the heart rate is observed during apneic spells in obstructive sleep apnea (OSA). We hypothesized that autonomic changes would affect frequency-domain measures of heart rate variability (HRV). METHODS: We studied 20 patients (15 men, 5 women, mean age 47.2 +/- 12.2 years) with suspected OSA undergoing overnight polysomnography, and five patients (4 men, 1 woman, mean age 49.2 +/- 8.6 years) with recently diagnosed sleep apnea undergoing polysomnography while wearing continuous positive airway pressure (CPAP). Holter monitors were applied during sleep studies and data were analyzed in 5-minute blocks over the course of the night. Using spectral analysis, low frequency (LF) and high frequency (HF) powers were calculated for each interval. Overall mean and standard deviation (SD) for LF power, HF power, and the LF:HF ratio were recorded for each patient. Comparisons were made between patients with severe OSA (apnea hypopnea index (AHI) > 30, n = 8), moderate OSA (AHI 1-30, n = 5), without OSA (AHI < 10, n = 7), and patients wearing CPAP (n = 5). RESULTS: Assessment of overnight LF or HF power revealed no significant difference between the four groups. The LF:HF ratio, which represents sympathovagal balance, was higher among those with moderate disease compared to normals and those with severe OSA (both P = 0.037). The standard deviation of the LF:HF ratio was higher among those with moderate disease compared to normals (P = 0.0064) and those with severe OSA (P = 0.0006). OSA patients receiving CPAP behaved like patients with moderate OSA, with increased SD of the LF:HF ratio. CONCLUSIONS: The observed changes in the LF:HF ratio and its SD suggest an increased sympathetic tone and discordance in sympathovagal activity in moderate OSA, which is blunted in severe OSA. CPAP may restore autonomic defects, characteristic of severe OSA, to moderate levels.

Adult↗

PubMed2003

Cephalometric assessment of craniofacial morphology in Chinese patients with obstructive sleep apnoea.

OBJECTIVE: To compare the differences in craniofacial morphology in Chinese patients with and without obstructive sleep apnoea (OSA). METHOD: We performed lateral cephalometric radiographs on 94 consecutive patients (77 males) referred with snoring or other symptoms suggestive of OSA for polysomnography (PSG). Significant OSA was defined as an apneoa-hypopnoea index (AHI) > or = 10/h of sleep on overnight PSG. The cephalometric data were compared between those with and without significant OSA. RESULTS: (mean +/- SD) There were 69 (56 males) with significant OSA with mean age 53 +/- 12 years, body mass index (BMI) 28.6 +/- 5.0 kg/m2, AHI 36.5 +/- 20.6/h, and minimum SaO2 76 +/- 14%. There were 25 controls (21 males) without significant OSA with similar age and BMI. The mandibular plane to hyoid bone distance (MPH) and the perpendicular distance from hyoid bone to the line connecting C3 vertebra and retrognathion (HHI) were significantly longer in the OSA patients. The angle measurement from sella to nasion to point A (SNA) was smaller in the OSA group. MPH distance was the only independent variable for significant OSA with an odds ratio of 3.47 (95% CI 1.39-8.66). Abnormalities of the MPH and SNA were more marked in the OSA patients with BMI > or = 30 kg/m2. CONCLUSIONS: Significant differences in craniofacial morphology are noted between OSA patients and non-apnoeic controls. An inferiorly positioned hyoid bone and a retropositioned maxilla may predispose obese patients to more severe OSA.

Analysis of Variance↗

PubMed2002

Acoustic rhinometry findings in patients with mild sleep apnea.

BACKGROUND: Nasal obstruction may contribute to the development of obstructive sleep apnea (OSA). Acoustic rhinometry (AR) measures nasal patency and congestion, which are useful parameters in objectively evaluating nasal obstruction. The nasal obstruction produced by allergic rhinitis may contribute to the development of OSA and can be easily assessed with AR. OBJECTIVE: This study was undertaken to assess the degree of nasal obstruction seen in allergic patients with and without OSA. STUDY DESIGN AND SETTING: This study was a retrospective data analysis from a tertiary referral center. The AR data from 10 patients with and 40 patients without mild OSA were compared. RESULTS: The mean congestion factors at the first cross-sectional area (CSA1) on the AR graph were found to be significantly higher in the OSA group than in the non-OSA group (P = 0.03). The classification of change in congestion factors demonstrated significant differences at CSA1, CSA2, and CSA3 and in volume (t distributions <0.001, 0.0312, <0.001, and <0.001, respectively). The non-OSA patients noted a significant subjective improvement in nasal congestion after topical nasal decongestion, whereas the OSA patients did not (P <or= 0.0001 and 0.064, respectively). CONCLUSION: Although the role of nasal obstruction in OSA is controversial, our study lends evidence to the thought that the nasal obstruction associated with allergic rhinitis is associated with the presence of mild OSA. SIGNIFICANCE: Whether allergic rhinitis is a direct cause of OSA is debatable, but we have shown that greater nasal congestion is related to the presence of OSA in a population of patients with allergic rhinitis.

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