Snoring and hypertension.
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Blood Pressure↗
Biomedical subjects
V Hoffstein
Publications and source records attributed to V Hoffstein.
Glottic dimensions in healthy men and women.
Glottic aperture is important in modulating respiratory system resistance. Male patients with obstructive sleep apnea (OSA) have a smaller glottic cross-sectional area compared to controls. Since OSA has a strong male predominance, we reasoned that glottic dimensions may differ between healthy men and women. Therefore, we utilized the acoustic reflection to measure glottic cross-sectional area in 44 non-smoking, non-obese, healthy subjects, 25 men and 19 women. Glottic area was measured during a continuous slow expiration from total lung capacity (TLC) to residual volume (RV). We compared glottic areas in men and women at three lung volumes: TLC, 50% of vital capacity (VC), and RV. We found that in all but 2 subjects, glottic areas at TLC was greater than at 50% VC or RV. At any given lung volume, there was no significant difference in glottic area between men and women. The reduction in glottic area between TLC and RV was also similar between men and women (36 +/- 24% and 33 +/- 21%, respectively). However, this reduction in glottic area occurred mainly at low lung volumes in women, and more uniformly throughout the vital capacity range in men. We conclude that changes in glottic dimensions are dependent on lung volume, that healthy men and women have similar glottic areas, and that the glottic aperture shows similar variation with lung volume among both sexes.
Adult↗
Tracheal hysteresis in sleep apnea.
The collapsibility of pharyngeal walls, characteristic of patients with obstructive sleep apnea, likely results from reduced tone of the pharyngeal muscles. This reduction in the upper airway muscle tone may not end at the pharynx but may extend further distally, e.g., into the trachea. Because tracheal tone cannot be measured directly in conscious humans, we inferred the tone from the relative hysteresis of the tracheal area compared with the lung. Relative hysteresis was measured by plotting the cross-sectional area of a tracheal segment obtained by the acoustic reflection technique vs. lung volume. All measurements were performed during wakefulness. We found that in 42 patients with obstructive sleep apnea (apnea/hypopnea index greater than 10), relative hysteresis of the proximal trachea was predominantly clockwise, i.e., smaller than that of the lung parenchyma; in the 33 nonapneic patients (apnea/hypopnea index less than or equal to 10), it was predominantly counter-clockwise, i.e., larger than that of the lung parenchyma. For the distal trachea all patients, apneic and nonapneic, had similar, clockwise, relative hysteresis. We conclude that reduction in the upper airway muscle tone in patients with obstructive sleep apnea extends into the trachea.
Adolescent↗
Glottic and cervical tracheal narrowing in patients with obstructive sleep apnea.
There are several studies showing that patients with idiopathic obstructive sleep apnea (OSA) have a narrow and collapsible pharynx that may predispose them to repeated upper airway occlusions during sleep. We hypothesized that this structural abnormality may also extend to the glottic and tracheal region. Consequently, we measured pharyngeal (Aph), glottic (Agl), cervical tracheal (Atr1), midtracheal (Atr2), and distal (Atr3) tracheal areas during tidal breathing in 66 patients with OSA (16 nonobese and 50 obese) and 8 nonapneic controls. We found that Aph, Agl, and Atr1, but not Atr2 or Atr3, were significantly smaller in the OSA group than in the control group. Obese patients with OSA had the smallest upper airway area, although the nonapneic controls had the largest areas. Multiple linear regression analysis revealed that the pharyngeal area, cervical tracheal area, and body mass index were all independent determinants of the apnea-hypopnea index, accounting for 31% of the variability in apnea-hypopnea index. Aph, Agl, and Atr showed significant correlation with the body mass index. We conclude that sleep-disordered breathing is associated with diffuse upper airway narrowing and that obesity contributes to this narrowing. Furthermore, we speculate that a common pathophysiological mechanism may be responsible for this reduction in upper airway area extending from the pharynx to the proximal trachea.
Adult↗
Clinical and laboratory features of acute sulfur dioxide inhalation poisoning: two-year follow-up.
We present clinical and laboratory results (including nuclear imaging) obtained over a period of two years in two nonsmoking miners who were exposed to high concentrations of sulfur dioxide (SO2) after a mine explosion. Within 3 wk of the accident, both miners had evidence of severe airways obstruction, hypoxemia, markedly reduced exercise tolerance, ventilation-perfusion mismatch, and evidence of active inflammation as documented by positive gallium lung scan. Serial ventilation-perfusion scans over the first 12 months showed progressive improvement without returning to normal. After the initial recovery, there has been no significant change over the subsequent two years postinjury. Pulmonary function and exercise tests also displayed a similar pattern of initial improvement. We conclude that (1) acute exposure to high concentrations of SO2 results in severe airways obstruction, (2) pulmonary function abnormalities are partially reversible, and (3) most of the improvement occurs within 12 months after the initial injury.
Accidents, Occupational↗
Flow-volume curves in snoring patients with and without obstructive sleep apnea.
To examine the usefulness of flow-volume curves as a screening test for the diagnosis of obstructive sleep apnea (OSA), we studied 405 consecutive patients referred for evaluation of possible OSA. All patients had full pulmonary function studies, which included measurements of maximal inspiratory and expiratory flow-volume curves, and nocturnal polysomnography, including continuous monitoring of snoring sounds. When the results were analyzed, of the 405 patients studied, 207 had OSA (apnea/hypopnea index [AHI] greater than 10) and 198 did not. Flow-volume curves were examined for the presence of upper airway obstruction defined as midvital capacity flow ratio (MVCFR = ratio of the maximal expiratory flow at 50% of vital capacity to maximal inspiratory flow at 50% of vital capacity) greater than 1.0. We found no significant difference in the values of MVCFR between the two groups: MVCFR was equal to 0.69 +/- 0.31 for nonapneic snorers, and 0.68 +/- 0.29 for the apneic snorers. Furthermore, we redefined the apneic and nonapneic groups using different cutoff values of AHI: 20, 30, 40, and 50. Independently of the AHI cutoff used, we found no significant difference in the MVCFR between the two groups. Linear regression analysis for the entire group of 405 patients revealed no significant correlation between MVCFR and the AHI or the snoring indices. We calculated the sensitivity, specificity, and predictive values of MVCFR for the diagnosis of OSA. We found that this test had 12% sensitivity, 86% specificity, 47% positive predictive value, and 46% negative predictive value.(ABSTRACT TRUNCATED AT 250 WORDS)
Female↗
Expiratory glottic widening in asthmatic subjects during exercise-induced bronchoconstriction.
Glottic caliber is modulated in a way that optimizes the airway resistance and the work of breathing. The midexpiratory glottic narrowing that normally occurs during tidal breathing is enhanced during histamine- or methacholine-induced airway narrowing. Exercise is associated with increased ventilatory demand and midexpiratory glottic widening in healthy subjects. However, the relative contribution of glottic aperture to airflow limitation during exercise-induced asthma is unknown. Consequently, we used the acoustic reflection technique to test whether a decrease in midexpiratory glottic size occurred also during exercise-induced bronchoconstriction in seven asthmatic subjects. Exercise resulted in a 38 +/- 16% (SD) fall in FEV1 from the baseline value (p less than 0.001) and a significant increase in midexpiratory glottic cross-sectional area from 1.89 +/- 0.45 cm2 before to 2.36 +/- 0.71 cm2 during bronchoconstriction (p less than 0.05). This midexpiratory glottic widening was also associated with increased tidal flow rates. We conclude that in marked contrast to airway obstruction induced by histamine or methacholine, exercise-induced asthma is associated with midexpiratory glottic widening, which occurs concomitantly with a decrease in lower airway caliber. We suggest that modulation of glottic aperture during acute asthma is heterogeneous and depends partly on the initiating stimulus.
Adult↗
Changes in pharyngeal properties after uvulopalatopharyngoplasty.
Uvulopalatopharyngoplasty is a commonly used modality for surgical treatment of snoring and obstructive sleep apnea. Although this procedure is thought to alter pharyngeal properties, its effect on pharyngeal mechanics has not been studied. The acoustic reflection technique was used to measure pharyngeal area at functional residual capacity and residual volume before and after uvulopalatopharyngoplasty in eight patients referred because of loud snoring. We also calculated the lung volume dependence of pharyngeal area, defined as the percent change in pharyngeal area between functional residual capacity and residual volume, normalized to the area at functional residual capacity. This parameter, which may be related to pharyngeal collapsibility, was obtained before and after uvulopalatopharyngoplasty. Preoperative sleep studies showed that one patient had obstructive sleep apnea (apnea index greater than 10). Uvulopalatopharyngoplasty resulted in a significant increase (p less than 0.01) in pharyngeal area (from 3.14 +/- 0.71 cm2 to 4.25 +/- 1.07 cm2) and residual volume (from 2.49 +/- 0.53 cm2 to 3.91 +/- 0.83 cm2). Following uvulopalatopharyngoplasty, the pharynx became stiffer, as manifested by a reduction in lung volume dependence of pharyngeal area from 19 +/- 12% to 8 +/- 13% (p less than 0.05). Six patients, including the patient with obstructive sleep apnea, reported improvement in snoring. Two patients reported worsening in snoring. One of the two was found to have reduction in pharyngeal area and lung volume dependence of pharyngeal area, and an increase in apnea index from 3 to 33. In selected snorers, uvulopalatopharyngoplasty results in improvement in snoring with a concomitant increase in pharyngeal area and a tendency toward lower pharyngeal collapsibility.
Adult↗
Infectious mononucleosis complicated by necrotizing epiglottitis, dysphagia, and pneumonia.
Although infectious mononucleosis is usually a benign illness, life-threatening complications may occur. We describe a 17-year-old pregnant girl who developed necrotizing epiglottitis and dysphagia progressing to aspiration pneumonia and respiratory failure. The factors predisposing to this life-threatening complication are discussed.
Adolescent↗
Lung volume-related changes in the pharyngeal area of obese females with and without obstructive sleep apnoea.
The majority of male patients with obstructive sleep apnoea (OSA) have an abnormal pharyngeal structure and function, with episodic complete airway occlusion during sleep. Since OSA is less common in females than in males, it is possible that other abnormalities are active in female patients with OSA. Consequently, we measured pharyngeal area and its lung volume-related changes (LVRC) from functional residual capacity (FRC) to residual volume (RV) in overweight females, 14 with OSA and 14 without OSA. Pharyngeal areas were measured using the acoustic reflection technique. While there were no significant differences in pharyngeal area between the OSA and control groups at either FRC (mean +/- SD, 3.49 +/- 0.46 cm2 vs 3.08 +/- 0.63 cm2) or RV (2.86 +/- 0.47 cm2 vs 2.67 +/- 0.49 cm2), the reduction in pharyngeal area between FRC and RV was significantly greater in the OSA group (0.63 +/- 0.23 cm2 vs 0.33 +/- 0.32 cm2, p less than 0.05). Furthermore, although the expiratory reserve volume (ERV) was not significantly different between the two groups (0.4 +/- 0.2 l vs 0.4 +/- 0.3 l), LVRC, defined as the reduction in pharyngeal area normalized by ERV, was significantly higher in the females with OSA than in the non-apnoeic controls (2.68 +/- 2.24 cm2.l-1 vs 1.17 +/- 1.23 cm2.l-1, p less than 0.02). We conclude that females with OSA have abnormal pharyngeal mechanics similar to males with OSA.
Adult↗
Determinants of blood pressure in snorers.
To examine the hypothesis that the tendency to raised blood pressure in snorers is associated with nocturnal hypoxaemia and snoring, blood pressure was measured and snoring, oxyhaemoglobin saturation (SaO2), and thoraco-abdominal movements were monitored overnight in 372 snorers. Snoring was quantified as number of snores per hour of sleep (snoring index). The data were analysed by multiple linear regression of diastolic blood pressure against age, body mass index (BMI), apnoea-hypopnoea index (AHI, number of episodes per hour), snoring index, and SaO2. Diastolic blood pressure correlated significantly with BMI, AHI, and mean nocturnal oxygen saturation, but not with the snoring index. However, snoring index correlated with BMI, AHI, and mean nocturnal oxygen saturation. Snoring is thus not a direct risk factor for hypertension, but may influence blood pressure via its association with obesity, obstructive sleep apnoea, and nocturnal hypoxaemia.
Age Factors↗
Comparison of glottic areas measured by acoustic reflections vs. computerized tomography.
We compared measurements of glottic area obtained by acoustic reflection technique with anatomically equivalent area measured from computerized tomographic (CT) scans of the neck in 11 subjects with glottic pathology. Both measurements were performed in the supine position during tidal breathing at functional residual capacity. We found excellent agreement in glottic areas obtained by both methods: the mean (+/- SD) values were 1.8 +/- 0.8 cm2 for the acoustic method and 1.7 +/- 0.9 cm2 for the CT method. Linear regression analysis revealed the following relationship between the area measured by acoustic technique (AAC) and that measured by CT (ACT): AAC = 0.81.ACT + 0.36. There was a significant correlation between the two measurements of glottic area (r = 0.95, P less than 0.0001). We conclude that the acoustic reflection technique may be used reliably in clinical and physiological studies concerned with glottic geometry.
Acoustics↗
Relative hysteresis of the airways and lung parenchyma in normal subjects.
We evaluated the mechanical properties of the airways sequentially from the glottis toward the main bronchi in 10 normal subjects. Plots of airway cross-sectional area vs. lung volume, measured during inspiration and expiration, were used to determine the relative magnitude of the airways vs. parenchymal hysteresis. Airway cross-sectional area was measured by means of the acoustic reflection technique. We found that the hysteresis of the proximal part of the trachea was greater than that of the lung parenchyma, whereas the hysteresis of the distal trachea and subcarinal segments of the airways was smaller than that of the lung parenchyma. The transition zone between the proximal and the more distal airway properties occurred 8-26 cm distal to the glottis. This transition zone was reproducible in its location on repeated testing in each subject but varied among subjects. To the extent that relative hysteresis of the airways depends on bronchomotor tone, our findings suggest that the bronchomotor tone is inhomogeneous, being maximal at the proximal part of the trachea and gradually decreasing toward the more distal trachea and subcarinal airway segments.
Acoustics↗
Dichotomous airway response to exercise in asthmatic patients.
The extent and location of airway narrowing in asthmatic subjects are usually inferred from measurements of maximal expiratory flow rates and airway resistance. In the present study, we used the acoustic reflection technique to measure the airway cross-sectional area in 14 asthmatic subjects and 8 normal controls before and following treadmill exercise tests. In normal subjects, exercise caused no significant change in FEV1 and bronchial area, but did cause a significant increase in the intrathoracic tracheal area from 2.0 +/- 0.7 cm2 to 3.1 +/- 0.7 cm2 (p less than 0.002). In the asthmatics, exercise was followed by a 37 +/- 15% reduction in forced expiratory volume in 1 s(FEV1), and a 36% decrease in bronchial area from 8.5 +/- 2.8 cm2 to 5.4 +/- 1.1 cm2 (p less than 0.001); however, extra- and intrathoracic tracheal areas increased significantly. These findings provide direct and quantitative evidence that the bronchi are the main site of airway narrowing in exercise-induced asthma, and draw attention to the phenomenon of tracheal dilatation that occurs concomitant with bronchoconstriction in asthmatic patients.
Adult↗
Improvement in upper airway function after weight loss in patients with obstructive sleep apnea.
Overweight patients with obstructive sleep apnea (OSA) are improved by weight reduction, although the underlying mechanisms are not clear. We tested the hypothesis that improvement in OSA after weight loss is associated with improvement in pharyngeal function. Consequently, we measured pharyngeal area at functional residual capacity (AFRC) and at residual volume (ARV), the percent change in pharyngeal area between FRC and RV (delta Aph%) defined as (AFRC - ARV)/AFRC x 100, and lung volume dependence of pharyngeal area (LVD) defined as the difference between AFRC and ARV normalized for the expiratory reserve volume (ERV)--in 12 overweight apneic patients before and after weight loss. We found that after a 26 +/- 18 kg weight loss, there was a significant reduction in the apnea/hypopnea index from 57 +/- 29 to 14 +/- 10 (p less than 0.0005) and increase in the lowest nocturnal oxygen saturation from 54 +/- 20% to 80 +/- 8% (p less than 0.001). This improvement was associated with a significant reduction in delta Aph% from 25 +/- 15% to 9 +/- 18% (p less than 0.05) and a significant decrease in LVD from 1.98 +/- 1.52 cm2/L to 0.16 +/- 0.88 cm2/L (p less than 0.005). There were four patients in whom baseline LVD was low and relatively unchanged after weight loss. Three of these patients exhibited paradoxical inspiratory narrowing of the glottis, which reversed after weight loss; these glottic abnormalities were not present in the rest of the patients with OSA. We conclude that improvement in obstructive sleep apnea after weight loss may be related to improvement in pharyngeal and glottic function.
Adult↗
Paradoxical glottic narrowing in patients with severe obstructive sleep apnea.
Most patients with obstructive sleep apnea have increased pharyngeal collapsibility (defined in the present study as an increased lung volume dependence of pharyngeal area), which predisposes them to upper airway occlusion during sleep. However, there are patients with severe obstructive sleep apnea who have low-normal pharyngeal collapsibility. The factors leading to nocturnal upper airway obstruction in such patients have not been ascertained. We studied 10 overweight male patients with severe obstructive sleep apnea and low-normal pharyngeal collapsibility to determine the site of upper airway pathology in these patients. We found that all 10 patients exhibited paradoxical inspiratory narrowing of the glottis during quiet tidal breathing. This phenomenon was not observed in a matched group of 10 snoring, nonapneic male controls. We conclude that paradoxical glottic narrowing may be a contributing factor in the pathogenesis of upper airway obstruction in patients with severe obstructive sleep apnea who have low-normal pharyngeal collapsibility.
Adult↗
Site of upper airway obstruction in patients with idiopathic obstructive sleep apnea.
We developed a technique to determine the site of upper airway obstruction in patients with idiopathic obstructive sleep apnea (OSA). This technique is based on the analysis of inspiratory airflow pressures at various levels of the pharyngeal airway during sleep. Pharyngeal pressure was measured by a moveable Millar catheter pressure transducer. The catheter's position in the airway was localized radiographically. Ten patients with OSA were tested: five patients were found to have upper airway obstruction at the level of the soft palate, and five had upper airway obstruction at the base of the tongue. We concluded that measuring airway pressures at multiple sites along the airway is useful in localizing the site of obstruction in patients with OSA, and may have important implications in terms of the patient's response to surgical treatment.
Adult↗
Neurosarcoidosis associated with hypersomnolence treated with corticosteroids and brain irradiation.
Narcoleptic features developed in a young man with CNS sarcoidosis. This was associated with a structural lesion in the hypothalamus as demonstrated on CT scans of the head. The diagnosis of narcolepsy was established by compatible clinical history and the Multiple Sleep Latency Test. Treatment with high-dose corticosteroids was ineffective, but when the low-dose, whole-brain irradiation was added, complete resolution of the narcoleptic features ensued.
Adult↗