Exercise responses during incremental and high intensity and low intensity steady state exercise in patients with obstructive lung disease and normal control subjects.

A study was undertaken to compare the cardiac and ventilatory responses to different types of exercise between 12 patients with COPD and ten normal age-matched control subjects. Both groups attained comparable heart rates and the percentage of their maximum predicted heart rate. Patients had a higher heart rate and VE with a lower O2P at every level of work load. Patients had a mean VT which approximated their FEV1 and increased their VE predominantly by increasing their respiratory frequency. During the low intensity test, despite the differences in work load, the patients had comparable heart rates and VE. No resting spirometric value accurately predicted work load, VE, or maximal VO2. We conclude that patients have a reduced work tolerance that is not adequately explained by their reduced lung function. Thus, cardiac factors, deconditioning, and the dyspneic sensation may be determinants of exercise limitation in some patients.

Analysis of the inspiratory flow-volume curve. Should it always precede the forced expiratory maneuver?

The inspiratory flow-volume (FV) curve can be used to identify patients with upper airway obstruction, air trapping, and restriction. Current computed pulmonary function testing equipment often mandates a forced expiratory maneuver (FEM) immediately prior to the forced inspiratory maneuver (standard method). We evaluated the inspiratory FV curve with and without an antecedent FEM in 119 subjects referred for pulmonary function testing. The subjects were divided into four groups by grading the degree of airway obstruction using confidence intervals of the FEV1/FVC percent predicted minus the actual FEV1/FVC percent measured from the best FEM according to Intermountain Thoracic Society recommendations. The forced inspiratory vital capacity (FIVC), forced inspiratory flow 50 (FIF50), and peak inspiratory flow (PIF) from the inspiratory FV curve with an antecedent FEM was compared with the FIVC, FIF50, and PIF without an antecedent FEM in each category of obstructive lung disease. The FIVC without the antecedent FEM was significantly larger than that with an antecedent FEM by 170 ml (p < 0.002) in subjects with severe airway obstruction, but was not significantly different in the other groups. The FIF50 was not significantly different in any group, but approached significance in both normal subjects and subjects with severe obstruction. The PIF was not significantly different in any group, but approached significance in the normal subjects, order for patients with severe obstructive airway disease to generate a valid forced inspiratory FV curve, it should be obtained without an antecedent FEM. When a plateau of the inspiratory FV curve is encountered, we suggest that is useful to generate the inspiratory FV curve prior to the FEM and to analyze its flow and volume characteristics independent of the FEM. The "best" inspiratory FV curve should then be displayed with the "best" FEM for proper evaluation of the FV loop.

Complex cryptococcal empyema.

Cryptococcus neoformans continues to present diagnostic and treatment challenges in patients with underlying malignant neoplasms. Cryptococcal empyema is a relatively rare complication of cryptococcal disease. It is important to distinguish whether uncontrolled malignancy or cryptococcal infection is responsible for the effusion. We used traditional diagnostic approaches, bronchoscopy and transthoracic fine needle aspiration, to verify the presence of the organism but continued to have treatment failure until adequate drainage was established.

The use of pulmonary function testing in piloting, air travel, mountain climbing, and diving.

Millions of people engage in occupational or leisure activities at high altitude or at variable depths below sea level. This article presents an overview of the utility of pulmonary function testing in evaluating complications and other consequences of exposure to high and low pressure environments. The authors review recent literature concerning expected changes in pulmonary function with hyperbaric and hypobaric exposures. The article provides guidance for clinicians evaluating mountain climbers, pilots, aircrew members, airline passengers and deep sea divers.

Nifedipine does not alter methacholine-induced bronchial reactivity.

Calcium ions have been shown to be involved in smooth muscle contraction and various secretory processes. Nifedipine, a calcium channel blocking drug, does not have any intrinsic bronchodilatory effect, but it has been suggested to possibly inhibit bronchial reactivity. Eight patients, with normal baseline pulmonary function studies and methacholine-induced bronchial reactivity, had a repeat metacholine challenge after nifedipine. Spirometry was obtained at baseline and three minutes after successive inhalations of normal saline and five, 15, 30, 50, 100 and 200 inhalation units of 0.5% methacholine. Plethysmographic lung volumes and airways resistance were measured at the start of the test and after the last inhalation of methacholine. The FEV1, FVC, MMEF and PEFR were reduced by an average of 35.6%, 20.6%, 54.4% and 30.6%, respectively, on the initial study, and by 35.4%, 20.5%, 54.8% and 34.5% after nifedipine. Airways resistance was increased by 249.3% in the initial study and by 265.7% after nifedipine. There was no statistical difference in baseline spirometry, spirometry obtained at any level of methacholine inhalation, or in airways resistance between the two studies. Despite comparable decreases in lung function, all patients were less symptomatic after receiving nifedipine. Nifedipine does not alter methacholine-induced bronchial reactivity. Until the role of nifedipine in asthma is better defined, caution should be used in prescribing nifedipine to asthmatic patients with heart disease, because their perception of airways resistance may be altered.