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Biomedical subjects

D A Mahler

Publications and source records attributed to D A Mahler.

At least 37 records · Page 2Linked to original sources
PubMed1997

Salmeterol reduces dyspnea and improves lung function in patients with COPD.

STUDY OBJECTIVE: To investigate the short-term effects of inhaled salmeterol on the perception of dyspnea and lung function in patients with COPD. DESIGN: Double-blind, crossover, randomized trial comparing inhaled salmeterol and inhaled placebo over 4 h. SETTING: Pulmonary function laboratory at university medical center. PATIENTS: Sixteen patients with symptomatic COPD and at least 200-mL increase in FEV1 after inhalation of two puffs (180 microg) of albuterol. INTERVENTIONS: Visit 1 was used for familiarization. At visits 2 and 3 (2 to 3 days apart), patients inhaled either two puffs of salmeterol (42 microg) or placebo. MEASUREMENTS AND RESULTS: Lung function and dyspnea were measured at 0.5, 2, and 4 h after inhalation of the study medication. Dyspnea was measured by the -5 to +5 category scale at rest and by the 0 to 10 category-ratio scale while breathing through inspiratory resistances of 5, 15, and 30 cm H20/L/s. Age was 66+/-8 years (mean+/-SD). FEV1 was 0.97+/-0.331 (51+/-13% predicted). There were significantly higher values for FEV1 and FVC (at all time periods) and lower values for functional residual capacity (at all time periods) and residual volume (at 4 h) with salmeterol than with placebo. There were significantly lower dyspnea ratings on the -5 to +5 category scale (p=0.03 at 2 h and p=0.02 at 4 h) and for the mean dyspnea scores during resistive breathing with salmeterol compared with placebo (p=0.002). CONCLUSIONS: Inhaled salmeterol reduced dyspnea, increased airflow, and reduced hyperinflation over 4 h in patients with symptomatic COPD.

Administration, Inhalation↗
PubMed1996

Descriptors of breathlessness in cardiorespiratory diseases.

The purposes of this study were: to examine the decriptors of breathlessness chosen by a large sample of patients with cardiorespiratory disease; to determine test-retest reliability of a patient's selection of the descriptors; and to assess whether a patient's recall of the experience of breathlessness is the same as that provoked by physical activity. Questionnaire data were collected at an initial visit for patients who complained of breathlessness and at a second visit in a subgroup of patients. A total of 218 patients who sought medical care for difficulty breathing due to one of seven different conditions were recruited from an outpatient pulmonary disease clinic at a university medical center. Patients selected statements that described qualities of breathlessness from a 15-item questionnaire and completed pulmonary function tests. At a subsequent visit (4 to 15 d later) a subgroup of 16 patients with chronic obstructive pulmonary disease (COPD) repeated the questionnaire at rest (to assess reliability) and after walking in a hallway to provoke a moderate intensity of breathlessness (to compare recall with direct experiences). The relationship among descriptors was evaluated by cluster analysis. The "work/effort" cluster was common for all diagnoses. Each condition was characterized by more than one cluster except COPD. Each diagnosis was associated with a unique set of dusters (e.g., asthma with "work/effort" and "tight," interstitial lung disease with "work/effort" and "rapid" breathing). Percent agreement for all descriptors selected at Visits 1 and 2 (recall) was 79% (r = 0.82; p = 0.001). Percent agreement at Visit 2 between descriptors for recall and for breathlessness provoked by walking was 68% (r = 0.69; p = 0.004). We conclude that patients with different cardiorespiratory conditions experience distinct qualities of breathlessness. Patients' recall of their sensations of breathlessness is reliable and comparable to dyspnea with walking. Employing a questionnaire containing descriptors of breathlessness may help to establish a specific diagnosis and to identify mechanisms whereby a specific intervention relieves dyspnea.

Adult↗
PubMed1996

Dyspnea ratings for prescribing exercise intensity in patients with COPD.

STUDY OBJECTIVE: We tested the hypothesis that patients with COPD can use dyspnea ratings obtained from a prior graded exercise test as a target to reliably produce specific exercise intensities. DESIGN: Four visits over a 7-week period. SETTING: Pulmonary function and cardiorespiratory exercise laboratory at a university hospital. PATIENTS: Fifteen symptomatic patients with stable COPD. Age was 68 +/- 7 (mean +/- SD) years. FEV1 was 1.12 +/- 0.22 L (45 +/- 8% predicted). INTERVENTIONS: At each visit, patients estimated the heaviness of weights to evaluate their magnitude estimation of a nonrespiratory task; after pulmonary function testing was completed, patients were tested on the cycle ergometer. At estimation trial 1 (day 0), patients estimated the intensity of dyspnea using the 0 to 10 category-ratio scale during an incremental exercise test. Estimation trial 2 (day 5 to 7) was the same as the previous trial. At production trials 1 (day 10 to 14) and 2 (day 40 to 44), patients were instructed to produce specific intensities of dyspnea (ie, dyspnea targets) at 50% and at anaerobic threshold (AT) or 80% of peak oxygen consumption (Vo2) as calculated from results at estimation trial 2. MEASUREMENTS AND RESULTS: Lung function was stable at all visits. Dyspnea ratings were 1.8 +/- 0.9 (range, 1 to 3) at 50% of peak Vo2 and 5.5 +/- 1.5 (range, 4 to 8) at AT/80% of peak Vo2 (17.0 +/- 3.4 mL/kg/min) at estimation trial 2. The individual percent changes in Vo2 at the lower dyspnea target were 12 +/- 19% and 11 +/- 19% for production trials 1 and 2, respectively, compared with estimation trial 2. At the higher dyspnea target, the corresponding individual percent changes in Vo2 were -4 +/- 9% and -7 +/- 11%, respectively. For all 15 patients, there were borderline statistical differences for the Vo2 values at the lower (p = 0.04 and p = 0.07) and at the higher (p = 0.04 for each production trial) dyspnea targets for production trials 1 and 2 compared with estimation trial 2. Two patients showed 50% or greater variability in the calculated exponent for magnitude estimation of weights. In a subgroup analysis of the 13 patients with reproducible magnitude estimation of the heaviness of weights, there were no significant differences in Vo2 for the two production trials compared with estimation trial 2 at both exercise intensities. CONCLUSIONS: Dyspnea ratings obtained from an incremental exercise test can be used as a target for patients with COPD to regulate/monitor the intensity of exercise training. The ability of patients with COPD to achieve a desired Vo2 based on an individual dyspnea target was generally more accurate at the higher exercise level (AT/80% of peak Vo2) compared with the lower intensity (50% of peak Vo2). Acceptable accuracy was maintained over a 5-week time period.

Aged↗
PubMed1995

Changes in dyspnea, health status, and lung function in chronic airway disease.

The purpose of this study was to examine longitudinal changes in clinical parameters in patients with chronic obstructive pulmonary disease (COPD). We postulated that progressive dyspnea and decline in lung function over time would influence or impact patient's health status. Clinical ratings of dyspnea, general health status, and physiologic lung function were measured every 6 mo over a 2-yr period in an original group of 110 male patients with stable but symptomatic COPD and no significant comorbidity. At enrollment, age was 67 +/- 8 yr (mean +/- SD), forced expiratory volume in one second (FEV1) was 1.28 +/- 0.59 I (44 +/- 17% of predicted), and forced vital capacity (FVC) was 2.84 +/- 0.84 I (68 +/- 18% of predicted). A total of 34 patients "dropped out" because of death (n = 20), relocation (n = 7), and other reasons (n = 7). Dyspnea was measured using the transition dyspnea index (TDI), which represented changes from the baseline state; general health status was measured using the Medical Outcomes Study (MOS) 20-item short-form survey; physiologic lung function was assessed by spirometry (FVC and FEV1) and inspiratory muscle strength (PImax). Statistical analyses were performed using all available data for each patient, including results until the time at which patients died or were lost to follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Evaluation of the short-form 36-item questionnaire to measure health-related quality of life in patients with COPD.

STUDY OBJECTIVE: To evaluate the short-form 36-item questionnaire (SF-36) as an instrument for measuring health-related quality of life (HRQL) in patients with symptomatic COPD. DESIGN: Observational data at a single point in time. SETTING: Outpatient pulmonary clinic. PATIENTS: Fifty male patients with COPD and no significant comorbidity. MEASUREMENTS AND RESULTS: HRQL was assessed with the SF-36, which consists of 36 questions that cover nine health domains. Clinical ratings of dyspnea were measured by the multidimensional baseline dyspnea index (BDI). Pulmonary function tests included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal inspiratory mouth pressure (PImax). The mean (+/- SD) age of the patients was 72 +/- 8 years. The BDI focal score was 5.6 +/- 2.3, FEV1 was 1.32 +/- 0.60 L (48 +/- 22% pred), and PImax was 62 +/- 23 cm H2O. The BDI focal score was significantly correlated with seven of nine components of the SF-36 (range of r, 0.42 to 0.91; p < 0.05). The FEV1 percent of predicted and PImax were significantly correlated with five of nine health components (range of r, 0.30 to 0.65 and 0.31 to 0.61, respectively). Using linear regression model analysis with the different SF-36 components as the dependent variable and BDI, FVC, FEV1, and PImax as independent variables, the BDI score was the only significant predictor of social and physical functioning, role-physical, vitality, pain, health perceptions, and health transition (p < 0.05). CONCLUSIONS: The SF-36 is a valid instrument to measure HRQL in patients with COPD. The severity of dyspnea but not respiratory function was a significant predictor of various components of HRQL.

Adult↗
PubMed1995

Diagnosis of chronic obstructive pulmonary disease and differentiation from asthma.

Asthma and chronic obstructive pulmonary disease are both common diseases, which together afflict approximately 25 million Americans. Although expiratory airflow obstruction is the common physiologic abnormality, asthma and chronic obstructive pulmonary disease are characterized by unique pathologic findings, clues from clinical histories, and laboratory test results. Despite some overlap in these characteristics, it is usually possible to differentiate these two conditions. This distinction is important for the healthcare provider to communicate a realistic prognosis to the patient and the patient's family, and to institute appropriate therapy.

Asthma↗
PubMed1994

Perception of breathlessness during exercise in patients with respiratory disease.

The perception of breathlessness during physical activities is a frequent and disturbing complaint for patients with chronic respiratory disease. Psychophysical principles can be applied to quantitate the severity of dyspnea during cardiopulmonary exercise testing. Power production (or work) appears to be the most appropriate stimulus for measuring the dyspnea response. The 0-10 category-ratio (CR-10) scale and the visual analog scale (VAS) are two instruments for measuring the intensity of breathlessness. Studies demonstrate that the slope and/or intercept of the power production-breathlessness relationship provide a valid, reliable, and responsive approach for measurement. Ratings of dyspnea during exercise are useful to determine the severity of breathing difficulty and to assess the efficacy of therapy.

Chronic Disease↗
PubMed1994

Does entrained breathing improve the economy of rowing?

A previous study has shown that subjects who entrain breathing during cycling exhibit a lower oxygen consumption (VO2) compared with random breathing. We sought to investigate the hypothesis that entrainment of breathing during rowing improved biomechanical economy (reduced VO2) compared with spontaneous breathing. A secondary hypothesis was that perceptual ratings of breathing difficulty would be lower with entrained breathing. Sixteen physically active male subjects (mean +/- SD age: 21 +/- 5 yr) with no previous rowing experience received instruction in rowing and then performed progressive incremental exercise on the variable-resistance rowing ergometer (Concept II, Morrisville, VT). Peak VO2 was 53.1 +/- 5.4 ml.kg-1.min-1. At three subsequent visits subjects rowed at power productions of 50% and 75% of peak VO2 for 6 min each. At each visit they were randomized to a specific pattern of breathing: inspire during drive, expire during recovery; expire during drive, inspire during recovery; or spontaneous breathing. At the end of each session subjects rated "breathing difficulty" using the 0-10 category-ratio scale. Analysis of variance revealed no significant differences in VO2, VO2/power production, or perceptual ratings at either intensity of exercise for the three different breathing patterns. Although our results do not support either the primary or secondary hypothesis, it is possible that any physiologic and/or perceptual benefits of locomotor-respiratory coupling might be specific for exercise mode or might require months to years of training.

Adult↗
PubMed1994

Clinical evaluation of exertional dyspnea.

The medical history is the first step in the clinical evaluation of exertional dyspnea. It should include pertinent questions about the characteristics of dyspnea, especially descriptive qualities, onset, frequency, severity, and activities that provoke the symptom. Based on this information, along with the physical examination, the health care provider should be able to categorize the cause of exertional dyspnea as suspected cardiac disease, suspected respiratory disease, or as unexplained. Laboratory testing is ordered using a logical approach to diagnose the most probable cause of dyspnea. Cardiopulmonary exercise testing is indicated to differentiate cardiac and respiratory limitation, to document deconditioning, and to identify psychogenic dyspnea. The measurement of dyspnea and leg discomfort during exercise testing can be performed using the Borg 0 to 10 category-ratio scale or the visual analog scale. These perceptual responses can provide useful information about symptom limitation, which is complementary to physiologic data.

Adult↗
PubMed1993

Evaluation of dyspnea in the elderly patient.

The symptom of dyspnea in the elderly person should not be considered part of the "normal aging process." Instead, the history, examination, and testing should focus on cardiac disease, respiratory disease, and deconditioning as the most likely causes. Because respiratory sensation is diminished with aging, breathlessness may not develop until a more advanced stage of disease or dysfunction. Clinical measurement of dyspnea is important to assess its severity and to evaluate response to treatment. Specific treatment should be directed toward the pathophysiology of the underlying disease. General strategies for relieving dyspnea include breathing techniques, exercise training and reconditioning, oxygen therapy, improved nutrition, and, in selective cases, psychotropic medication.

Aged↗
PubMed1993

Exercise-induced asthma.

Bronchoconstriction associated with exercise can occur in nearly all individuals with asthma and in 35-40% of those with allergic rhinitis/hay fever symptoms. This represents approximately 12-15% of the population. Exercise-induced asthma (EIA) is a clinical syndrome characterized by transient airflow obstruction typically 5-15 min after cessation of physical exertion. Symptoms may include chest tightness, breathlessness, coughing, and/or wheezing. Some individuals may experience delayed bronchoconstriction (late phase response) 6-10 h after completing exercise. Approximately 40-50% of those with asthma exhibit a "refractory period", i.e., diminished bronchoconstriction to exercise performed within 2 h. The pathophysiology of EIA is related to thermal events within the intrathoracic airways. Alterations in the temperature of the airways and/or osmolarity in the epithelial lining fluid cause release of mediators in the airways and the development of bronchoconstriction. Although EIA can be strongly suspected by an appropriate history, pulmonary function testing is necessary to make a specific diagnosis. Measurement of lung function is an important first diagnostic test. If there is no evidence of airflow obstruction at rest, then either bronchoprovocation testing or exercise challenge testing is indicated. Nonpharmacologic therapy includes "warm-up" exercise prior to training or competition to induce a "refractory period" and to prevent/reduce bronchoconstriction. An inhaled beta 2-adrenergic agonist, e.g., albuterol, is usually effective for preventing/treating EIA. Cromolyn sodium is an alternative class of medication that inhibits both the early and late phase responses. Other bronchodilator agents are available if combination therapy with an inhaled beta 2-adrenergic agonist and cromolyn sodium is not effective.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Obstruction↗
PubMed1992

A factor analysis of dyspnea ratings, respiratory muscle strength, and lung function in patients with chronic obstructive pulmonary disease.

The purpose of this study was to demonstrate that clinical ratings of dyspnea and physiologic function are separate dimensions underlying the pathophysiology of chronic obstructive pulmonary disease (COPD). We used principal-components factor analysis to confirm these dimensions using data collected prospectively in 86 symptomatic patients with COPD. Three different instruments were used to rate dyspnea: a modified Medical Research Council (MRC) scale, the oxygen cost diagram (OCD), and the baseline dyspnea index (BDI). Measures of physiologic function included standard spirometric measures (forced vital capacity [FVC] and forced expiratory volume in one second [FEV1]) and maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures. Age of the 65 male and 21 female subjects was 62.9 +/- 1.2 yr (mean +/- SEM). All three clinical scales were significantly correlated with physiologic function (range of r values, 0.32 to 0.45; p less than 0.05), except for the relationship between the MRC scale and PEmax (r = -0.14; p = NS). The factor analysis yielded three factors that accounted for 71.9% of the total variance of the data: clinical ratings of dyspnea (MRC scale, OCD, and BDI) loaded on the first factor; maximal respiratory pressures and gender loaded on the second factor; and lung function and age loaded on the third factor. Additional post hoc factor analysis provided similar results when the sample was divided into two subgroups by randomization, by severity of dyspnea ratings, or by severity of airflow obstruction. We conclude that dyspnea ratings, maximal respiratory pressures, and lung function are separate factors or quantities that independently characterize the condition of patients with COPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Dyspnea↗
PubMed1992

Right ventricular function at rest and during exercise in chronic obstructive pulmonary disease.

Right ventricular ejection fraction (RVEF), a measure of systolic pump performance of the right ventricle, is frequently depressed at rest or during exercise in patients with chronic obstructive pulmonary disease (COPD). The most common cause of reduced RVEF in COPD is augmentation of right ventricular afterload, namely an increase in pulmonary artery pressure and pulmonary vascular resistance. Therapy with agents that decrease the afterload on the right ventricle have the potential to improve the systolic performance of this chamber. Oxygen, vasodilators such as hydralazine and nifedipine, theophylline, and sympathomimetics all may augment RVEF in part by reducing pulmonary vascular resistance and, in some cases, pulmonary artery pressures in patients with COPD and cor pulmonale. However, only oxygen therapy has been shown to improve survival.

Digitalis↗
PubMed1992

Impact of dyspnea and physiologic function on general health status in patients with chronic obstructive pulmonary disease.

STUDY OBJECTIVE: To examine the relationship among clinical dyspnea ratings, physiologic pulmonary function, and general health status in symptomatic patients with chronic obstructive pulmonary disease (COPD). DESIGN: Observational data collected at a baseline state. SETTING: Outpatient pulmonary disease clinics at a university hospital and two VA medical centers. PATIENTS: One hundred ten male patients with COPD with no significant comorbidity were recruited. MEASUREMENTS AND RESULTS: Clinical ratings of dyspnea were measured by the multidimensional baseline dyspnea index (BDI). Pulmonary function tests included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal inspiratory mouth pressure (PImax). General health status was assessed with the Medical Outcomes Study short-form survey, which consists of 20 questions that cover six health components. The mean age of the patients was 67 +/- 8 yr (+/- SD). The mean value for FVC was 2.84 +/- 0.84 L (68 +/- 18 percent of predicted), for FEV1 was 1.28 +/- 0.59 L (44 +/- 17 percent of predicted), and for PImax was 59.0 +/- 25.0 cm H2O. The BDI score and PImax were significantly correlated with five of the six components of general health status. Only three of the six components of general health were significantly correlated with FEV1 as percent predicted (rs value range, 0.30 to 0.44) and with FVC as percent predicted (rs value range, 0.25 to 0.33). Statistical comparisons showed that the BDI score had significantly higher correlations than FVC (percent predicted), FEV1 (percent predicted), and PImax values with physical functioning and role functioning. Multiple linear regression analysis showed that the BDI score was the only statistically significant predictor of role functioning, mental health, and health perceptions for general health status, whereas both the BDI score and FEV1 (percent predicted) were independent predictors of physical functioning and social functioning. CONCLUSION: Dyspnea ratings influence and predict general health status to a greater extent than do physiologic measurements in symptomatic patients with COPD. A shift in focus from the pathophysiology of disease to assessment and relief of symptoms may provide more meaningful benefits for the individual patient in terms of quality of life. This consideration requires that health-care providers use available measuring tools in clinical practice to quantify symptoms, as well as overall health status.

Adult↗
PubMed1992

The measurement of dyspnea during exercise in patients with lung disease.

The measurement of dyspnea during an exercise task provides an opportunity to simulate daily physical activities that lead to breathing difficulty in patients with lung disease. Although the exact stimulus for the sensation of breathlessness is unknown, it is possible to measure dyspnea during exercise by applying the principles of psychophysics to the analysis of various stimulus-response relationships. It is logical to consider that the exercise task, ie, work or power production, causes both physiologic and perceptual responses. A 0 to 10 category scale with ratio properties developed by Borg and a visual analogue scale are the most commonly used instruments for rating the severity of dyspnea during exercise. The ratings of breathlessness are generally reliable over time and are sensitive to evaluate an acute intervention in patients with stable respiratory disease. The exercise intensity-dyspnea relationship appears to be the most appropriate stimulus-response relationship for quantifying dyspnea during exercise.

Dyspnea↗
PubMed1991

Measurement of breathlessness during exercise in asthmatics. Predictor variables, reliability, and responsiveness.

The purpose of this study was to determine the predictor variables for breathlessness and to investigate the criteria of reliability and responsiveness for measuring breathlessness during progressive, incremental exercise on the cycle ergometer. We studied a heterogeneous group of patients with stable asthma (mean +/- SEM age, 46 +/- 4 yr) for four visits at weekly intervals. Predictor variables were determined at the first visit. Nine independent physiologic variables were obtained at each minute during exercise; the Borg rating of breathlessness (range 0 to 10) was used as the dependent variable. The regression model relating the physiologic parameters to the Borg rating of breathlessness was highly significant (model F = 43.4; p = 0.0001). Backward elimination selected the strongest predictors of the Borg rating: peak inspiratory flow (VI); tidal volume (VT)/FVC; frequency of respiration (f); and peak inspiratory mouth pressures (Pm). These four variables explained 63% of the variance in the rating of dyspnea. Each of the four variables exhibited a linear relationship with the Borg rating. Test-retest reliability was assessed by comparing results at the first and second visits. Individual slopes (except for VT/FVC) and intercepts for the four predictor variables versus Borg ratings were highly reliable. The slope for work intensity (watts) and Borg ratings, but not the intercept, was highly reliable. Responsiveness was evaluated by randomly administering inhaled methacholine or inhaled metaproterenol, alternately, at the third and fourth visits to induce acute changes in lung function before exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Locomotor-respiratory coupling develops in novice female rowers with training.

The purpose of this study was to investigate the hypothesis that locomotor-respiratory coupling (LRC), or entrainment of breathing, develops in the sport of rowing as a result of training. We prospectively evaluated exercise responses over an 8 month training session (October to May) in 12 female subjects who were members of the Dartmouth College novice rowing team. Progressive, incremental exercise testing was performed on the variable-resistance rowing ergometer (Concept II, Morrisville, VT). To relate the pattern of breathing to the mechanics of rowing, the catch and finish of each rowing stroke during the last 30 s of each minute of exercise were marked on the strip chart paper that recorded inspiratory flow measured by using a heated pneumotachograph. Age was 18 +/- 1 yr (mean +/- SE); weight was 67.5 +/- 2.1 kg. Peak oxygen consumption (VO2) increased by 10% from October (40.8 +/- 0.6 ml.kg.min-1) to May (P less than 0.001). Chi-square goodness-of-fit analysis was used to assess whether the proportion of inspirations occurring in each of four quadrants of circle plots representing repetitive rowing strokes exercise intensities of 100 watts (W) and peak VO2 were random or corresponded to a regular pattern of breathing. Although 5 of 12 subjects demonstrated LRC at exercise of 100 W in October, there was no significant change at this submaximal intensity over the training season. Only 2 of 12 subjects showed LRC at peak exercise in October, but there was a significant increase (P = 0.003) in the number of subjects who entrained breathing in Jan (10/12) and May (8/12).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗