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Biomedical subjects

V Hoffstein

Publications and source records attributed to V Hoffstein.

At least 109 records · Page 6Linked to original sources
PubMed1988

Snoring and upper airway properties.

Habitual snoring in adults may be related to upper airway dysfunction, although the precise relationship has never been studied. We quantitatively measured snoring and correlated it with upper airway properties in 50 apneic and 59 nonapneic adult male patients. Both groups were similar in terms of nasal airflow resistance and pulmonary function tests. We found a significant correlation between the severity of snoring and nasal airflow resistance in both groups, and between the severity of snoring and pharyngeal and glottic areas in the apneic group. We conclude that snoring may be associated with abnormalities in upper airway properties.

Adult↗
PubMed1988

Morphologic diagnosis of idiopathic pulmonary alveolar lipoproteinosis-revisited.

The usefulness of transbronchial biopsy in diagnosing idiopathic pulmonary alveolar lipoproteinosis (PAL) is not emphasized in the literature. Therefore, we decided to reassess our approach to the morphologic diagnosis of this disorder in 14 patients diagnosed over the past 13 years in two major teaching hospitals in Toronto. The morphologic diagnosis of idiopathic PAL was established by means of open lung biopsy in 11 patients; the use of transbronchial biopsy was not considered in eight of them. Transbronchial biopsy was performed in six patients, and the diagnosis of idiopathic PAL was reliably established in five cases. We conclude that transbronchial biopsy may be a worthwhile preliminary procedure to open lung biopsy in patients with suspected idiopathic PAL, and it can reliably establish the diagnosis in such cases.

Adolescent↗
PubMed1988

Fatal pulmonary emboli in hospitalized patients. An autopsy study.

To determine the accuracy of the antemortem diagnosis of major pulmonary embolism, we reviewed 1276 autopsy reports at St Michael's Hospital, Toronto, from 1980 to 1984. Of 44 patients identified with major pulmonary embolism as the cause of death or a major factor contributing to it, 14 (31.8%) had the diagnosis suspected before death. We could not find any distinctive features separating these patients from those in whom the diagnosis of pulmonary embolism was not suspected before death. We conclude that major pulmonary embolism is still underdiagnosed in hospitalized patients, despite the availability of lung scanning and pulmonary angiography.

Cause of Death↗
PubMed1987

Pharyngeal structure and function as a determinant of sleep-related breathing disorders: a unifying hypothesis.

We propose a hypothesis which relates the pathogenesis of various sleep-related breathing disorders such as snoring, obstructive sleep apnea, and central sleep apnea to pharyngeal structure and function, i.e. pharyngeal area and compliance; these easily measured mechanical properties of the pharynx reflect the complex integrated response of upper airway muscles to changes in neural drive. Our arguments, although hypothetical, are based on the already existing measurements of pharyngeal dynamics in patients with sleep-related breathing disorders. If confirmed, this hypothesis would allow to predict a particular breathing disorder occurring during sleep from simple mechanical measurements performed in an awake subject, and furthermore it would help us to understand the effect of recent therapeutic modalities used in treatment of sleep apnea.

Humans↗
PubMed1987

Effect of mouthpiece, noseclips, and head position on airway area measured by acoustic reflections.

To investigate whether it is possible to simplify the methodology of measuring airway area by acoustic reflections, we measured upper airway area in 10 healthy subjects during tidal breathing according to seven different protocols. Three protocols employed custom-made bulky mouthpiece with or without nose-clips, two protocols used a scuba-diving mouthpiece and cotton balls placed in the nostrils instead of noseclips, and two protocols employed neck flexion and extension. We found no significant difference in average pharyngeal, glottic, and tracheal areas for any of the protocols except for neck flexion, which was associated with a significantly lower mean pharyngeal area. Intraindividual variabilities were comparable for all protocols, except for protocol employing the customary bulky mouthpiece and no noseclips, which consistently resulted in the most variable measurements of area for all three airway segments: pharynx, glottis, and trachea. Furthermore, we found that the protocol employing the scuba-diving mouthpiece with or without cotton balls in the nostrils resulted in the lowest number of unacceptable measurements. We conclude that measurements of airway area by acoustic reflections may be further simplified by using a scuba-diving mouthpiece without noseclips; furthermore, control of head position during measurements is not critical provided there is no obvious neck flexion.

Acoustics↗
PubMed1987

In vivo estimation of tracheal distensibility and hysteresis in normal adults.

We used the acoustic reflection technique to measure the cross-sectional area of tracheal and bronchial airway segments of eight healthy adults. We measured airway area during a slow continuous expiration from total lung capacity (TLC) to residual volume (RV) and during inspiration back to TLC. Lung volume and esophageal pressure were monitored continuously during this quasi-static, double vital capacity maneuver. We found that 1) the area of tracheal and bronchial segments increases with increasing lung volume and transpulmonary pressure, 2) the trachea and bronchi exhibit a variable degree of hysteresis, which may be greater or less than that of the lung parenchyma, 3) extrathoracic and intrathoracic tracheal segments behaved as if they were subjected to similar transmural pressure and had similar elastic properties, and 4) specific compliance (means +/- SE) for the intrathoracic and bronchial segments, calculated with the assumption that transmural pressure is equal to the transpulmonary pressure, was significantly (P less than 0.05) smaller for the intrathoracic segment than for the bronchial segment: (2.1 +/- 2.0) X 10(-3) cmH2O-1 vs. (9.1 +/- 2.1) X 10(-3) cmH2O-1. Direct measurements of airway area using acoustic reflections are in good agreement with previous estimates of airway distensibility in vivo, obtained by radiography or endoscopy.

Acoustics↗
PubMed1987

Changes in pharyngeal cross-sectional area with posture and application of continuous positive airway pressure in patients with obstructive sleep apnea.

In an attempt to elucidate whether changes in posture (from sitting to supine) result in reduction in pharyngeal area, thus promoting pharyngeal occlusion during sleep in so predisposed persons, we studied 12 snoring apneic patients and 6 snoring nonapneic control subjects. in all subjects, we employed acoustic reflection technique to measure pharyngeal area at FRC sitting and supine. We also examined changes in pharyngeal area resulting from the application of positive intrapharyngeal pressure in sitting and supine posture. We found that (1) pharyngeal cross-sectional area at FRC was similar in both groups, (2) decrease in pharyngeal area with assumption of supine posture was also similar in both groups (21 +/- 11% in patients with OSA versus 15 +/- 13% in nonapneic control subjects), and (3) pharyngeal distensibility was significantly higher in apneic snorers than in nonapneic control subjects (0.090 +/- 0.039 cm H2O-1 in apneic snorers versus 0.032 +/- 0.027 cm H2O-1 in nonapneic control subjects; p less than 0.005). We conclude that changes in posture alone are not sufficient to convert a snorer into a patient with OSA; however, when physiologic abnormalities ("floppy" pharynx) are superimposed on postural reduction in pharyngeal area, airway occlusion results.

Humans↗
PubMed1987

Differences in pharyngeal properties between snorers with predominantly central sleep apnea and those without sleep apnea.

The underlying cause of idiopathic central sleep apnea syndrome is not well understood. We therefore examined the possibility that patients with idiopathic central sleep apnea may have abnormalities of upper airway mechanics that might contribute to the pathogenesis of central apneas. The acoustic reflection technique was used to assess pharyngeal size, lung volume dependence, and pharyngeal "compliance" in 8 patients with idiopathic central sleep apnea, all of whom were snorers, and in 8 weight-matched, snoring control subjects with normal sleep studies. Patients with central sleep apnea when compared with control subjects exhibited markedly increased specific pharyngeal "compliance" (0.12 +/- 0.05 versus 0.03 +/- 0.01 cm H2O-1; p less than 0.001), increased change in pharyngeal area from FRC to RV (0.8 +/- 0.5 versus 0.03 +/- 0.3 cm2; p less than 0.05), and a larger pharyngeal area at FRC (4.7 +/- 0.9 versus 3.8 +/- 0.8 cm2; p less than 0.03). We conclude that increased pharyngeal "compliance" and lung volume dependence may play a role in the etiology of central apneas in this syndrome.

Brain Diseases↗
PubMed1987

Airway area by acoustic response measurements and computerized tomography.

In order to determine more precisely the accuracy with which the acoustic reflection technique (ART) can infer airway area during spontaneous breathing, we compared acoustic measurements of airway area with equivalent areas measured from computerized tomographic (CT) scans of the neck and chest in 7 patients (mean age, 54 yr; range, 33 to 69 yr) with a history of upper airway abnormalities. At the time of the study, all patients were clinically stable and had no recurrent nerve palsy. Measurements of airway area by ART and CT were performed in the supine posture while patients breathed quietly at FRC. We found that there was considerable intersubject variability in area-distance functions determined by acoustic reflections. None of the subjects had a flat tracheal plateau. Once the acoustic and CT data were aligned, we compared cross-sectional areas at various distances from the glottis. Comparison points were separated by 1 cm, and as many as 13 different CT sections were used in some subjects. Mean values for all data points (n = 83) were 2.45 +/- SD = 0.69 cm2 and 2.56 +/- SD = 0.82 cm2 for the acoustic and CT methods, respectively, Z = 0.93; p greater than 0.05. Linear regression analysis revealed a correlation coefficient (r) of 0.92; p less than 0.0001. On the basis of these findings, we conclude that the acoustic reflection technique may be used reliably for clinical and physiologic studies of the upper airways in humans.

Acoustics↗
PubMed1987

Central sleep apnea reversed by continuous positive airway pressure.

Continuous positive airway pressure (CPAP) is an accepted and highly effective method used in the treatment of obstructive sleep apnea (OSA). We have explored the potential utility of CPAP in a patient with sleep apnea without a major contribution of airway obstruction as measured by the usual criteria. The patient showed dramatic clinical and laboratory improvement in central apnea when treated with CPAP. A low level of CPAP (7.5 cm H2O) resulted in the reduction of central apneas from 281 to 32 per night with no significant change in obstructive apneas, which increased from 43 to 59 per night. On a separate night, a higher level of CPAP (12.5 cm H2O) resulted in virtually complete removal of all apneas. Measurement of pharyngeal properties revealed pharyngeal cross-sectional area in the low normal range, but increased pharyngeal compliance. This case illustrates that pharyngeal abnormalities may be present in patients with central sleep apnea, and CPAP may be beneficial in the treatment of this disorder. Although the exact mechanism of action of CPAP in this disorder is unclear, we propose several possibilities that may account for the beneficial effect of CPAP in this patient.

Adult↗
PubMed1987

Pulmonary function in smokers after short-term cessation of alcohol ingestion.

To test whether acute alcohol withdrawal has an effect on pulmonary function, we studied 33 smoking alcoholics admitted for a four-week period of rehabilitation during which they consumed no alcohol. Flow-volume curves, lung volumes by body plethysmography, and single breath diffusing capacity for carbon monoxide were measured on admission, at two weeks, and at four weeks. We found no significant change in pulmonary function between the results on admission and after four weeks of abstinence from alcohol. We conclude that short-term cessation of alcohol did not significantly influence pulmonary function in our subjects.

Adult↗
PubMed1986

Pharyngeal size in snorers, nonsnorers, and patients with obstructive sleep apnea.

We measured pharyngeal cross-sectional area and its change with alterations in lung volume in 10 subjects who snored and had obstructive sleep apnea, 6 subjects who snored and did not have obstructive sleep apnea, and 9 subjects who did not snore. Pharyngeal area was measured with use of an acoustic-reflection technique. We found that snorers with and without sleep apnea had a significantly smaller mean (+/- SE) pharyngeal cross-sectional area (4.1 +/- 0.2 and 3.7 +/- 0.9 cm2, respectively) at functional residual capacity than nonsnorers (5.4 +/- 0.5 cm2, P less than 0.025). When lung volume decreased from functional residual capacity to residual volume, both nonsnorers and snorers with sleep apnea had a decrease in pharyngeal area (from 5.4 +/- 0.5 to 4.5 +/- 0.4 cm2 and 4.1 +/- 0.2 to 3.4 +/- 0.2 cm2, respectively), whereas snorers without sleep apnea had no such decrease, suggesting that their pharynxes were less collapsible at low lung volumes. We conclude that snorers with and without sleep apnea have smaller pharyngeal cross-sectional areas than nonsnorers and that snorers with sleep apnea have a further decrease as lung volume falls.

Adult↗
PubMed1986

Effect of CO2 concentrations on acoustic inferences of airway area.

To determine the effect of gas composition on the accuracy of measurements of airway area and distance using an acoustic reflection technique, we employed glass-tube models to simulate pharyngeal (Phar-model), laryngeal (Lar-model), and tracheal (Trach-model) regions of upper and central airways. We made repeated measurements of area-distance functions using gas mixtures containing 0, 2, 4, 6, 8, and 10% CO2, 80% He, and balance O2. The actual area of the model was calculated from the roentgenographic data and compared favorably with an area measured by acoustic reflections using a gas mixture containing 0% CO2. With the different gas mixtures, calculated area was overestimated only at the highest levels of CO2, with Phar-model area increasing from (mean +/- SD) 4.66 +/- 0.03 cm2 measured with 0% CO2 to 4.93 +/- 0.05 cm2 (P less than 0.05) measured with CO2 concentration of 10%. To assess the effect of CO2 concentration on measurements of distance, we isolated two discrete points located in the Phar-model and Lar-model regions. When measurements were performed using 10% CO2 mixture, Phar-model point was shifted by 1.02 +/- 0.03 cm and Lar-model point was shifted by 2.16 +/- 0.09 cm away from the microphone compared with their axial position determined, using 0% CO2 mixture (P less than 0.05). Differences in area-distance calculations at the higher levels of CO2 did not exceed the within-run variability of the technique (10 +/- 4%). We conclude that CO2 absorbers are not required during measurements of airway area by acoustic reflections, provided CO2 concentration does not exceed 10%.

Acoustics↗