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Biomedical subjects

V Hoffstein

Publications and source records attributed to V Hoffstein.

At least 55 records · Page 3Linked to original sources
PubMed1994

Astrocytoma presenting with apnea and sinus arrest.

Although some vascular lesions of the central nervous system are known to cause abnormalities in the control of breathing, association between astrocytoma and combined cardiorespiratory abnormalities in the adult is distinctly unusual. We present a case of a 52-year-old man whose only features of astrocytoma consisted of episodes of apnea and sinus arrest followed by prolonged alveolar hypoventilation. These abnormalities resolved after resection of the tumor. We conclude that in patients presenting with respiratory and sinus arrest, the search for a cause should not be limited to the cardiac and pulmonary systems, but it must include a possibility of a brain tumor.

Apnea↗
PubMed1993

Tuberculosis presenting with generalized lymphadenopathy, pulmonary infiltrates, and bone destruction in a young man.

Although tuberculosis is still relatively common in Canada, particularly among recent immigrants, one tends not to consider it very strongly in the absence of definite pulmonary symptoms and in the face of negative smears of expectorated sputum and bronchial washings. We present the case of a young immigrant from Ethiopia who presented with mild constitutional symptoms, bony tenderness of the chest wall, generalized lymphadenopathy, and rib erosions--a set of features which, in the face of smear-negative sputum and bronchial washings, raised a possibility of lymphoma. Eventually, diagnosis of tuberculous lymphadenitis and osteomyelitis was established and the patient responded well to appropriate therapy.

Adult↗
PubMed1993

Effect of nasal dilation on snoring and apneas during different stages of sleep.

This study was designed to test the hypothesis that nasal dilation reduces snoring. To achieve this we performed nocturnal polysomnography, including measurement of snoring, in 15 patients without nasal pathology before and after insertion of a nasal dilator (NOZOVENT). Snoring was quantified for each sleep stage by recording the number of snores per minute of sleep, number of snores per minute of snoring time and nocturnal sound intensities (maximum, average and minimum). We found that nasal dilation had no effect on the number of apneas, hypopneas or oxygen saturation. Snoring parameters were unaffected by NOZOVENT during stages I, II and REM sleep, but were all significantly reduced during slow wave sleep. We conclude that dilation of the anterior nares in patients without nasal pathology has a relatively weak effect on snoring, and routine use of nasal dilating appliances is not recommended for treatment of snoring.

Adult↗
PubMed1993

Tracheobronchial dilation during isocapnic hypoxia in conscious humans.

To assess the effects of isocapnic hypoxia on the pharynx, glottis, extrathoracic trachea (ET), intrathoracic trachea (IT), and main bronchi (MB), we measured the cross-sectional areas of these airways by acoustic reflection technique in 15 healthy volunteers. Measurements were made during tidal volume breathing while subjects were normoxic [arterial O2 saturation (SaO2) > 95%] or were made hypoxic by a rebreathing procedure. Under hypoxemic conditions, airway cross-sectional areas increased significantly at ET, IT, and MB levels (P < 0.001). The magnitude of this dilation was similar for both levels of hypoxemia studied (SaO2 80-85% and 70-75%); at the milder of the two hypoxemic conditions, ET cross-sectional area increased by 12.4 +/- 4.2% (SE), IT by 10.2 +/- 5.9%, and MB by 19.1 +/- 3.2%. No significant changes were found in the pharyngeal or glottic areas. Dilation was not produced by normoxic isocapnic hyperventilation, and the use of hypoxic airway gas mixtures did not artifactually alter acoustic reflection measurements in a mechanical model. Vagal airway tone, as reflected by airway constriction during pauses in tidal breathing, was unaffected by isocapnic hypoxia. We conclude that isocapnic hypoxia produces dilation of the trachea and major bronchi, an effect unaccounted for by an alteration in the ventilatory pattern.

Adult↗
PubMed1993

Determinants of continuous positive airway pressure level for treatment of obstructive sleep apnea.

The purpose of this study was (1) to examine the factors that account for the variability in continuous positive airway pressure (CPAP) levels required to abolish obstructive sleep apnea (OSA) in patients with this disorder, and (2) to examine the feasibility of predicting the lowest effective pressure (CPAPmin) from simple anthropometric and polysomnographic variables easily available in all patients considered for home CPAP therapy. To accomplish these tasks we studied a group of 208 patients with OSA all of whom were treated with nasal CPAP at home. We first analyzed a model set of 38 patients all of whom had at least two polysomnographic studies (the diagnostic one and a subsequent one to determine CPAPmin for home use), anthropometric measurements (including body mass index, neck circumference, and waist circumference), pulmonary function measurements (lung volumes, airways resistance, and flow-volume curves), pharyngeal and glottic cross-sectional areas at functional residual capacity and residual volume, and nasal airflow resistances. We compared patients requiring CPAP > 10 cm H2O with those who required CPAP < 5 cm H2O. The high CPAP group was characterized by a greater degree of obesity, more severe sleep apnea, and more collapsible pharynx. Multiple linear regression analysis using principal components and Mallows C(P) statistics revealed that the optimal set of predictors for CPAPmin consisted of only three variables: apnea/hypopnea index, body mass index, and neck circumference. This model accounted for 76% of the variability in CPAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Assessment of airway tone in asthma. Comparison between double lung transplant patients and healthy subjects.

We investigated the hypothesis that asthmatic patients have an increased cholinergic tone by measuring tracheobronchial cross-sectional areas during transient voluntary apnea. This allowed us to assess bronchomotor tone without the influence of changes in lung recoil or lung volume. Three groups of subjects with potentially different levels of tracheobronchial tone were studied: 14 healthy volunteers (N), 18 stable asthmatic patients (A), and 10 double lung transplant recipients (T). Using the acoustic reflection technique, we measured changes in tracheobronchial cross-sectional areas during short periods (5 to 10 s) of voluntary apnea. In a subset of subjects, studies were repeated before and after the inhalation of the muscarinic antagonist ipratropium. During breath-holding, glottis and extrathoracic trachea remained unchanged but intrathoracic tracheal area decreased by 30 +/- 8% (mean +/- standard error of the mean) in N, by 27 +/- 3% in A, and by 9 +/- 4% in the T group. Bronchial areas decreased by 24 +/- 8% in N, by 45 +/- 3% in A, and by 10 +/- 4% in T. These differences among groups were statistically significant at the tracheal and bronchial levels (p < 0.05), and ipratropium significantly inhibited this airway constriction (p < 0.05) only in the asthmatic group. Assuming that changes in cross-sectional airway areas voluntary apnea reflect airway tone, these results support the view that in humans this tone is mainly vagally controlled and that it is significantly increased in asthmatic compared with nonasthmatic subjects.

Administration, Inhalation↗
PubMed1993

Snoring and nasal resistance during sleep.

Although it is widely accepted that nasal obstruction leads to snoring and sleep apnea, the relationship between these variables is not clear, mainly because of the lack of studies in which nasal resistance (Rna) and snoring were measured concurrently. The authors studied eight nonapneic snoring men with healthy noses by nocturnal polysomnography that included quantitative assessment of snoring and concomitant nasal resistance. In six of these eight patients nasal resistance increased during sleep, but there was no significant change for the group as a whole between wakefulness (0.209 +/- 0.224 Pa/cm3 per second) and sleep (0.292 +/- 0.203 Pa/cm3 per second). Linear regression analysis showed no significant correlation between sleeping nasal resistance and snoring index (partial R2 = .44, P = .071). We used each subject as his own control and compared the snoring profile at a time during sleep when nasal resistance was at its highest (0.550 +/- 0.375 Pa/cm3 per second) and lowest (0.146 +/- 0.090 Pa/cm3 per second) levels. Despite the significant (P < .01) differences in nasal resistance, they were not reflected in the number of snores or their sound intensity. It is concluded that nasal obstruction during sleep is not correlated significantly to frequency or intensity of snoring during exclusively nasal breathing.

Adult↗
PubMed1993

Handedness and sleep apnea.

Left-handedness is associated with shorter life span. Many of the factors contributing to this higher mortality (eg, alcohol consumption, automobile accident, smoking) are the same as in patients with sleep apnea, who also have higher mortality than nonapneic controls. The authors hypothesized that (1) there is a higher prevalence of sinistrality in patients suspected of having sleep apnea than in the general population, and (2) left-handed persons with sleep apnea have a more severe disorder than right-handed ones. These hypotheses were tested in a prospective cohort of 970 patients referred to a sleep disorders center because of suspected sleep apnea. All patients underwent nocturnal polysomnography and measurements of blood pressure. Sixty-one patients were left-handed. The distribution of handedness as a function of age in this cohort was similar to that in the general population. There were 486 patients with an apnea/hypopnea index greater than 10; of these, 34 were left-handed, and 452 were right-handed. Oxygen saturation, blood pressure, age, smoking history, and body mass index were similar in both groups. Left-handed patients with sleep apnea had a significantly higher respiratory disturbance index (RDI) than the right-handed ones (52 +/- 30 vs 38 +/- 35 [p < 0.005]). Right-handed patients were distributed equally among RDI quartiles, but 41 percent of the left-handed patients were within the highest RDI quartile, compared to 12 percent within the lowest quartile. Sinistrality appears to be associated with more severe sleep apnea, which may help to explain the higher mortality seen among the left-handed persons.

Adult↗
PubMed1993

Predictive value of clinical features in diagnosing obstructive sleep apnea.

We examined the predictive value of history and physical examination in the diagnosis of obstructive sleep apnea (OSA) syndrome. This was achieved by studying a set of 594 patients referred to the sleep clinic because of suspicion of sleep apnea. All patients were asked a set of standard sleep-related questions and all had nocturnal polysomnography. We used stepwise multiple linear regression analysis to examine the relationship between the apnea/hypopnea index (AHI), defined as the number of episodes of cessation of breathing per hour of sleep (dependent variable), and age, sex, body mass index (BMI) and replies to the sleep questionnaire (independent variables). We found that age, sex, body mass index, bed partner observation of apnea and pharyngeal examination were significant predictors of AHI, explaining 36% of the variability. Subjective impression of the examining clinician was also an independent significant predictor of AHI, accounting for 10% of the variability. Using a conventional cutoff value of 10 to divide patients into apneics (AHI > 10) and nonapneics (AHI < or = 10), the sensitivity of subjective impression was 60% and the specificity 63%. We conclude that although clinical features obtained during history and physical examination explain a relatively high percent of the variability in AHI, subjective clinical impression alone is not sufficient to reliably identify patients with or without sleep apnea.

Adult↗
PubMed1992

Heterogeneous airway tone in asthmatic subjects.

We examined the effect of volume history on the dynamic relationship between airways and lung parenchyma (relative hysteresis) in 20 asthmatic subjects. The acoustic reflection technique was employed to evaluate changes in airway cross-sectional areas during a slow continuous expiration from total lung capacity to residual volume and inspiration back to total lung capacity. Lung volume was measured continuously during this quasi-static maneuver. We studied three anatomic airway segments: extra- and intrathoracic tracheal and main bronchial segments. Plots of airway area vs. lung volume were obtained for each segment to assess the relative magnitude and direction of the airway and parenchymal hysteresis. We also performed maximal expiratory flow-volume and partial expiratory flow-volume curves and calculated the ratio of maximal to partial flow rates (M/P) at 30% of the vital capacity. We found that 10 subjects (group I) showed a significant predominance of airway over parenchymal hysteresis (P < 0.005) at the extra- and intrathoracic tracheal and main bronchial segments; these subjects had high M/P ratios [1.53 +/- 0.27 (SD)]. The other 10 subjects (group II) showed similar airway and parenchymal hysteresis for all three segments and significantly lower M/P ratios (1.16 +/- 0.20, P < 0.01). We conclude that the effect of volume history on the relative hysteresis of airway and lung parenchyma and M/P ratio at 30% of vital capacity in nonprovoked asthmatic subjects is variable. We suggest that our findings may result from heterogeneous airway tone in asthmatic subjects.

Adolescent↗
PubMed1992

The effect of snoring on mean arterial blood pressure during non-REM sleep.

The purpose of this study was to examine the relationship between snoring and mean arterial blood pressure during sleep. This was accomplished by performing continuous, all-night, simultaneous measurements of snoring, oxygen saturation, sleep stages, and arterial blood pressure in a group of eight snorers and five nonsnoring control subjects. The results were analyzed to determine whether changes in mean arterial blood pressure during non-rapid-eye-movement (non-REM) sleep are different in snorers from those in nonsnorers and whether they are related to nocturnal hypoxemia. Both groups were similar with respect to their anthropometric parameters and sleep architecture. Oxygen saturations during different stages of non-REM sleep were similiar within each group. However, the analysis of variance revealed that among snorers mean arterial blood pressure increased slightly during slow-wave sleep, whereas the nonsnorers reduced their blood pressure by 17.4 +/- 3.7% compared with wakefulness values. We also performed multiple linear regression analysis for the entire group of 13 subjects using the change in mean arterial blood pressure relative to wakefulness as the dependent variable and snoring frequency and mean arterial oxygen saturation as the independent variables; the results demonstrated that only snoring frequency, and not oxygen saturation, correlated significantly with the change in mean arterial blood pressure. We conclude that snoring may influence variation of blood pressure during sleep, preventing the normally observed reduction of arterial blood pressure associated with slow-wave sleep.

Adult↗
PubMed1992

Treatment of obstructive sleep apnea with nasal continuous positive airway pressure. Patient compliance, perception of benefits, and side effects.

Obstructive sleep apnea is a chronic disease whose treatment may require long-term nightly use of relatively cumbersome and expensive breathing equipment that provides continuous positive airway pressure (CPAP) via nasal mask. Compliance with this treatment may be influenced not only by the objective improvement in sleep apnea but also by the patient's subjective perception of the benefit, bed mate or family support, side effects, and cost. The last factor may not be important in Ontario, where 75% of the cost is paid by the Ministry of Health. The goal of this study was to analyze the factors that may influence patient acceptance of nasal CPAP. This was done by tabulating the responses to a detailed questionnaire mailed to 148 patients with obstructive sleep apnea (OSA). There were 96 replies. We were able to contact by telephone an additional 42 patients. The results showed that 105 patients continued to use CPAP at a mean follow-up time of 17 +/- 11 months, some for as long as 6 yr. The majority of patients (81%) perceived CPAP as an effective treatment of the disorder, 5% were unsure, and 14% believed that CPAP was ineffective, despite the resolution of sleep apnea on polysomnography. Subjective improvement reported by the patients was also observed by the family members in 83% of the patients. The most common complaint, voiced by 46% of the patients, was nocturnal awakenings. Nasal problems, such as dryness, congestion, and sneezing, were the second most frequent complaint present in 44% of the responders.(ABSTRACT TRUNCATED AT 250 WORDS)

Costs and Cost Analysis↗
PubMed1992

Changes in cross-sectional airway areas induced by methacholine, histamine, and LTC4 in asthmatic subjects.

To examine whether leukotrienes, histamine, and methacholine have different sites of bronchoconstrictor action, we studied 8 stable asthmatic subjects (mean age +/- SD, 26 +/- 5 yr) on 3 different days. On each day, a randomized challenge with LTC4, methacholine, or histamine was performed until the dose that provoked a fall of 20% in FEV1 (PC20) was obtained. Complete and partial flow-volume curves as well as area-distance profiles generated by the acoustic reflection technique (ART) at a fixed lung volume were obtained in all subjects before and after each inhalation challenge. No significant differences were found in pulmonary function or baseline cross-sectional airway areas for the different study days. The three agonists provoked significant (p less than 0.05) bronchoconstriction at the level of the main bronchi when identical falls of FEV1 were achieved. Similarly, equal reductions of V30p were elicited by the three agonists. However, LTC4 and methacholine induced additional tracheal constriction but histamine inhalation did not. These differences in the degree of tracheal constriction were statistically significant (p less than 0.05; ANOVA). These results may be explained by distinct pharmacologic properties of the agents used and may have relevance in the understanding of the pathophysiology of asthma.

Analysis of Variance↗
PubMed1992

Nasal airway dilation and obstructed breathing in sleep.

Nasal respiratory airflow resistances of awake snorers averaged 0.188 +/- 0.165 Pa/cm3/s (N = 306) and were not elevated beyond the normal range (less than 0.25 Pa/cm3/s). Resistances were decreased substantially from a mean of 0.164 +/- 0.128 to 0.065 +/- 0.037 Pa/cm3/s (N = 72) by a nasal vestibular dilator (Nozovent). Effects of the dilator on breathing disorders in sleep were determined by polysomnographic recordings that included frequency, duration and intensity of snoring, apneas, hypopneas, and oxygen saturation in 10 heavy snorers while asleep with and without the dilator in situ over periods of several hours. No significant changes were detected in these parameters in any stage of sleep.

Adolescent↗
PubMed1992

The effect of unilateral and bilateral nasal obstruction on snoring and sleep apnea.

The purpose of this study was to compare apnea and snoring in patients with different patterns of nasal resistance: normal, high unilateral, and high bilateral. The authors examined 683 unselected patients referred for evaluation of snoring and possible sleep apnea. All patients had determination of nasal resistance (performed during wakefulness in the seated posture) and nocturnal polysomnography including quantitative measurement of snoring. Analysis of variance showed no significant difference in apnea and snoring indices among the three nasal resistance groups (normal, high unilateral, and high bilateral). Furthermore, there was no significant difference in the frequency of patients with different severity of apnea and snoring among the three groups. It is concluded that 1. unilateral and bilateral elevation of nasal resistance may lead to equally severe snoring or apnea; 2. there is no direct relationship between awake seated nasal resistance measurement and sleep disordered breathing; and 3. measurements of supine nasal resistance during sleep may be required to elucidate the relationship between sleep-disordered breathing and nasal obstruction.

Airway Resistance↗
PubMed1992

Evening-to-morning blood pressure variations in snoring patients with and without obstructive sleep apnea.

This study was designed to test a hypothesis that patients with sleep apnea have higher blood pressure in the morning, following a night spent in apnea and hypoxemia, than in the evening. To accomplish this, we prospectively studied a set of 611 patients referred to our clinic because of suspicion of sleep apnea. All patients had full nocturnal polysomnography, including measurement of snoring. Blood pressure was measured in the evening, prior to onset of sleep, and in the morning, immediately on awakening. We found that patients without apnea and hypoxemia had lower blood pressure in the morning compared with the evening value, while patients with severe sleep apnea and hypoxemia had higher blood pressure in the morning; these evening-to-morning blood pressure differences, although statistically significant, were small, typically 1 to 4 mm Hg. Morning blood pressures were higher in patients with sleep apnea and hypoxemia than in nonapneic normoxic patients. However, this difference disappeared after the groups were matched for age and body mass index. We conclude that (1) patients with sleep apnea and nocturnal hypoxemia lose the expected morning dip in arterial blood pressure, and (2) age and body mass index are more important correlates of blood pressure than apnea and nocturnal oxygen desaturation. We speculate that the loss of evening-to-morning drop in blood pressure, if present over a long period of time, may lead to sustained elevations in arterial blood pressure frequently observed in patients with sleep apnea.

Blood Pressure↗
PubMed1992

Alveolar damage due to inhalation of amitrole-containing herbicide.

Amitrole-containing herbicides are commonly used by home and cottage owners for spraying grass. They are manufactured and distributed in the United States, Canada and throughout the world by several pharmaceutical/chemical industries under many different trade names, such as Amitrole-T, Amizol, Azolan, Cytrol and Weedazol. They have not been previously associated with pulmonary toxicity in man or laboratory animals. We describe the first case in which inhalation of amitrole herbicide resulted in diffuse, asymmetric, severe alveolar damage, which was reversed after treatment with high-dose corticosteroids.

Aged↗