Ventilatory control during sleep in the elderly.

This review has briefly discussed the normal control of respiration during sleep with aging. Although we still do not have a complete understanding of ventilatory control during sleep in the elderly, it is clear that disorders of ventilation during sleep are clinically important in older overweight individuals. The identification of risk factors in this group will lead to an increased awareness and diagnosis of these disorders and therefore result in the development of rational approaches to the management of these individuals.

Weight loss in mildly to moderately obese patients with obstructive sleep apnea.

The therapeutic effects of weight loss were evaluated in 15 hypersomnolent patients with moderately severe obstructive sleep apnea. As patients decreased their body weight from 106.2 +/- 7.

A shift from central and mixed sleep apnea to obstructive sleep apnea resulting from low-flow oxygen.

Low-flow oxygen decreases the frequency of the 3 types of apnea (central, mixed, and obstructive) in patients with predominantly obstructive sleep apnea. The decrease in frequency appears to be accompanied by a shift in apnea distribution, consisting of a decrease in the proportion of central and mixed apneas and an increase in that of obstructive apneas. To determine whether this shift represents a greater inhibitory effect on central and mixed apneas or an increased tendency toward obstructive apneas, we administered low-flow oxygen during sleep to 9 patients who demonstrated predominantly central and mixed sleep apnea (51 +/- 33% and 33 +/- 21% of apneic events, respectively, mean +/- SD) and had resting, room air, oxygen tensions of 83 +/- 11 mmHg.

Cryptogenic hemoptysis. Clinical features, bronchoscopic findings, and natural history in 67 patients.

We reviewed the clinical outcome of 67 patients with hemoptysis and a normal or nonlocalizing chest roentgenogram and nondiagnostic fiberoptic bronchoscopic examination. During a 38 +/- 22 (SD) month period after bronchoscopy, 57 (85%) patients remained well without evidence of active tuberculosis or overlooked bronchogenic carcinoma, and 9 patients died of nonpulmonary conditions. One patient developed bronchogenic carcinoma 20 months after bronchoscopy and resolution of symptoms.

Inhibitability and enhanceability of basophil histamine release in asthmatic and normal subjects.

Circulating human basophils contain histamine, a potent mediator of inflammation. Previous in vitro studies have shown that histamine 'releasability' in asthmatic subjects differs from normal subjects but have not evaluated possible differences in the immunopharmacological control of the release of this mediator which might account for these differences. The purpose of the present study was to examine the immunopharmacologic control of basophil histamine release in 14 asthmatics and 10 normal subjects who were characterized by pulmonary function tests, allergic status (skin tests and serum IgE levels) and nonspecific airways reactivity to methacholine and histamine.

The effects of oxygen in patients with sleep apnea.

The effects of 6 h of continuous low flow, nasally administered oxygen were compared with the effects of breathing air in 10 men and 2 women with obstructive sleep apnea and daytime hypersomnolence. The overall quality of sleep, sleep fragmentation, the pattern of breathing, nocturnal oxygenation, and the clinical effects on daytime hypersomnolence determined by multiple sleep latency testing were evaluated. We found that in non-REM sleep, breathing 3 L/min of oxygen increased baseline percent arterial oxyhemoglobin saturation and decreased both the rate of sleep-disordered breathing from 69 +/- 36 to 56 +/- 39 (mean +/- SD) (p less than 0.

Evaluation of sleep-disordered breathing. Is polysomnography necessary?

To determine whether polysomnography is necessary to assess the presence and severity of sleep-disordered breathing, bedside observations by physicians were compared with the results of polysomnography in 37 patients with clinically suspected obstructive sleep apnea. Physician observations correlated with objective findings from polysomnography in detecting the presence of obstructive apnea (p less than 0.01), and had a high specificity and positive predictive value.

Effect of alpha-adrenergic blockade on exercise-induced asthma and conditioned cold air.

Cooling and drying of the intrapulmonary airways have been shown to be important stimuli for the development of bronchospasm induced by exercise and isocapnic cold air hyperventilation. It has also been suggested that alpha-adrenergic receptor activity is increased at lower temperatures. To evaluate the role of alpha-adrenergic activity in the development of bronchoconstriction during airway cooling, we examined the effects of alpha-adrenergic blockade with phentolamine on bronchospasm induced by exercise and isocapnic cold air hyperventilation in 8 asthmatics.

Radionuclide localization of massive pulmonary hemorrhage.

Lung scans with technetium sulfur colloid were performed in ten patients with life-threatening hemoptysis and nondiagnostic chest roentgenograms. Localized deposition of radionuclide was demonstrated in five of the six patients who were studied during active bleeding. These abnormalities were confirmed bronchoscopically in four patients, and lung scans provided clinically useful information regarding the bleeding site that had not been available from the medical history, physical examination, or chest roentgenogram.

Exercise-induced asthma. Physiologic and clinical considerations.

This article discusses the physiologic and clinical aspects of exercise-induced asthma. Alterations in heat and water exchange in the respiratory tract appear to be important in initiating exercise-induced asthma, which can be reproduced by isocapneic hyperventilation with cold dry air. These pulmonary responses are also closely related to the level of non-specific airways hyperreactivity.

Upper airway function in burn patients. Correlation of flow-volume curves and nasopharyngoscopy.

To determine whether upper airway dysfunction is detectable in patients with thermal injury, flow-volume curves were performed in 42 burn patients who were at risk for acute upper airway obstruction. Eighteen (42.9%) patients had abnormal inspiratory curves that were consistent with variable extrathoracic obstruction, a finding in only 8 (16%) of 50 nonburn control patients (p less than 0.

Flow-volume curves and sleep-disordered breathing: therapeutic implications.

To assess the relationship of abnormal flow-volume curves during awake periods to the clinical severity of sleep-disordered breathing and the need for surgical treatment of obstructive sleep apnoea, flow-volume curves were measured in 72 adults with obstructive apnoea. Patients in whom surgery was recommended for standard clinical indications had significantly lower inspiratory flow rates (p less than 0.01) and a higher incidence of flow-volume curves indicating extrathoracic airway obstruction (p less than 0.

Effects of blood transfusion on exercise capacity in patients with sickle-cell anemia.

Although sickle cells have increased intracellular viscosity, the viscosity of patient's blood is usually not increased, because of the low hematocrit typically found in such patients. When patients receive transfusions, their exercise capacity increases, but it is unclear whether the change is due primarily to increased hemoglobin concentration, or also reflects improved flow properties of the blood due to dilution of sickle cells with normal erythrocytes. To evaluate the relative importance of these two factors, submaximal exercise studies were performed before and after a series of transfusions.

CT demonstration of pharyngeal narrowing in adult obstructive sleep apnea.

Sleep apnea is a major cause of daytime hypersomnolence. Among the proposed etiologies, focal obstruction of the airways at the level of the pharynx has been suggested but not proven. Using computed tomography, the cross-sectional area of the airway can be readily assessed.

Computerized tomography in obstructive sleep apnea. Correlation of airway size with physiology during sleep and wakefulness.

Pathophysiologic changes during sleep in patients with obstructive apnea are often associated with alterations in upper airway function during awake periods. To determine whether these functional changes are related to abnormal airway structure, we performed computerized tomography (CT) in 20 awake patients with obstructive apnea and in 10 control subjects. The CT scan measurements of cross-sectional areas of the nasopharynx, oropharynx, and hypopharynx in apneic patients were significantly reduced (p less than 0.

The effects of protriptyline in sleep-disordered breathing.

The effects of therapy with the tricyclic antidepressant protriptyline were studied in 12 patients with hypersomnolence and moderately severe sleep apnea. After treatment there was no significant change in the duration or frequency of sleep-disordered breathing (SDB) during non-REM sleep, but there was an alteration in the breathing pattern characterized by a decrease in the amount of apnea during SDB events. Apnea, as a percent of disordered breathing time, fell from 60.

Hemodynamic mechanisms in anaphylaxis.

Intravenous administration of ascaris suum antigen (1 mg) as well as histamine (5 mg) was associated with rapid and marked reductions in cardiac output (QT) and systemic arterial pressure (Pa) in anesthetized mechanically ventilated dogs. When venous return was maintained constant by an external pump reservoir system, both antigen and histamine caused rapid reductions in the reservoir blood volume consistent with peripheral pooling. In addition, interruption of the splanchnic arterial inflow by occlusion of the descending thoracic aorta restored the cardiac output to control during histamine shock, whereas QT during antigen shock was unaffected by aortic occlusion, even though the circulatory failure was of similar magnitude.

The effect of alpha adrenergic blockade on non-specific airways reactivity and exercise induced asthma.

In asthmatics, alpha-adrenergic blockage with oral phentolamine partially or completely blocked bronchospasm after maximal exercise challenge. Bronchial reactivity to isocapnic hyperventilation with conditioned cold air was also reduced. However, non-specific airways reactivity to inhaled histamine did not change.

A screening test for airways reactivity. An abbreviated methacholine inhalation challenge.

A screening test to measure nonspecific airways reactivity was developed and compared to a standard methacholine inhalation challenge in 13 asthmatic patients and ten normal control subjects. The screening challenge consisted of one deep breath, then four breaths of a 5 mg/ml methacholine solution followed by one and four breaths of 25 mg/ml of methacholine. Subjects with a history of wheezing received the 5 mg/ml of methacholine first while those without a history of asthma began the challenge at the 25 mg/ml methacholine concentration.

Effects of antihistamines and indomethacin on hyperosmolar-induced vasodilation.

The circulatory effects of iv injections of hyperosmolar solutions were studied both in intact dogs with aortic flow probes and in dogs using a standard right heart-bypass preparation. Serial iv injections of 20 ml of 10% NaCl or 50 ml of 25% mannitol produced reproducible episodic vasodilation characterized by falls in mean aortic pressure from 99 +/- 10 (SE) to 61 +/- 6 Torr and increases in aortic flow from 2.20 +/- 0.

Abnormal inspiratory flow-volume curves in patients with sleep-disordered breathing.

Although flow-volume curves are valuable in detecting extrathoracic airway obstruction, their role in testing patients with sleep-disordered breathing is undefined. To determine whether patients with sleep-disordered breathing have abnormal flow-volume curves consistent with variable extrathoracic obstruction, 60 subjects referred with suspected sleep disorders prospectively underwent spirometry and assessment of flow-volume curves. These tests were interpreted independent of the outcome of polysomnography.

Physiologic manifestations of human anaphylaxis.

In the course of a controlled study to evaluate different forms of immunotherapy for subjects with insect-sting hypersensitivity, we observed 11 subjects who had systemic cutaneous urticarial reactions and 3 subjects who experienced systemic anaphylaxis. With the exception of tachycardia, there were no cardiopulmonary changes in the subjects with urticaria, whereas the major manifestation of anaphylactic shock in the other three subjects was severe hypotension that was probably secondary to peripheral vasodilation. Significant abnormalities in gas exchange developed in two subjects.