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Biomedical subjects

K R Chapman

Publications and source records attributed to K R Chapman.

At least 73 records · Page 4Linked to original sources
PubMed1994

Patient handling of a multidose dry powder inhalation device for albuterol.

BACKGROUND: Studies have suggested that novel inhaling devices may be misused by patients and medical personnel in the clinical setting soon after their introduction. to assess the adequacy of patient handling of a newer multidose dry powder albuterol inhaler, we conducted a comprehensive survey of use in primary and respiratory practices. METHODS: Patients 6 years of age and older and requiring inhaled beta 2-agonist for the treatment of stable obstructive airways disease were recruited from the practices of primary care and specialist physicians. After instruction from their physician or clinic staff in the use of a multidose dry powder albuterol inhalation device (Diskhaler), patients used the device in unblinded fashion for 2 weeks instead of their usual beta 2-agonist. After 2 weeks, patient use of the device was assessed at a return clinic visit. RESULTS: A total of 4,529 patients with reversible airways obstruction participated in a 2-week assessment of the device and compared it with their previous beta 2-agonist delivery system. Significantly more patients preferred the dry powder device (54 percent) over their previous device (29 percent) (p < 0.001), with 17 percent expressing no preference. After instruction, 98.5 percent of patients could demonstrate adequate use at the initial visit. Performance difficulties at the initial visit resulting in exclusion from the trial were infrequent but more common in the elderly (3 percent vs 0.2 percent for all other age groups combined, p < 0.001). Despite adequate use at the initial visit, at the conclusion of the trial, incorrect use of the device was noted in 10.2 percent of the elderly vs 3.2 percent of all other age groups combined (p < 0.001). Albuterol delivered by Diskhaler was well tolerated in all patient groups. CONCLUSIONS: A majority of patients are able to use a multidose dry powder albuterol inhaler device in the clinical setting, and prefer the device to previously used beta 2-agonist inhalation devices. However, follow-up shows that problems with device handling may become apparent in as little as 2 weeks after initial instruction, thereby mandating the need for periodic follow-up and reinstruction.

Administration, Inhalation↗
PubMed1994

Long-term xanthine therapy of asthma. Enprofylline and theophylline compared. International Enprofylline Study Group.

BACKGROUND: Enprofylline is a new xanthine derivative that shares theophylline's bronchodilator properties but is free of theophylline's adenosine receptor antagonist activity. We compared the long-term efficacy and tolerability of enprofylline and theophylline given over a 1-year period to adults with asthma. METHODS: Patients were recruited from 18 centers and 4 countries to participate in a 1-month double-blind comparison of enprofylline or theophylline in the treatment of asthma and were subsequently maintained on a regimen with the assigned medication for a further 11 months. The dosage of each xanthine was incremented from 150 mg twice daily at initiation to 300 and later 450 mg twice daily depending on the patient's tolerance and, in the case of theophylline, the rapidly assayed serum theophylline level. Patients kept a diary in which they recorded peak expiratory flow rate (PEFR) measured morning and evening, asthma symptom score, and the number of beta 2-agonists taken. Spirometry was checked at clinic visits at 3, 6, 9, and 12 months following randomization. RESULTS: Three-hundred forty-eight patients (174 enprofylline, 174 theophylline) participated in the trial. For both drugs there were significant improvements in PEFR and FEV1 during the first month of treatment with no significant difference between drugs (0.25 L for enprofylline vs 0.30 L for theophylline). Similarly, there were no differences in clinical outcome such as asthma exacerbations or beta 2-agonist usage between the two groups over follow-up. However, inhaled steroid dosage was more likely to have been incremented in theophylline-treated than enprofylline-treated patients (18% vs 8%, p = 0.025). Both drugs produced a modest increase in heart rate throughout the trial (approximately 5 beats/min). In 31 patients (26 enprofylline, 5 theophylline), asymptomatic elevations in aspartate aminotransferase and/or alanine aminotransferase occurred at least once during the study. In five patients (four enprofylline, one theophylline), the increase exceeded three times the upper limit of the normal range. In some subjects receiving enprofylline, serum enprofylline levels rose progressively despite constant oral dosage of the drug. CONCLUSIONS: Long-term xanthine therapy is well-tolerated by most adult asthmatics. However, long-term enprofylline administration may be associated with elevation in liver enzyme levels and unpredictable blood levels, thereby limiting its clinical usefulness.

Adolescent↗
PubMed1994

Assessment of an ambulatory care asthma program.

In response to rising asthma morbidity and mortality, numerous comprehensive asthma programs have been developed. However, few studies have examined critically the effectiveness of such programs or the means by which treatment or outcome is altered. To assess the role of a specialized ambulatory asthma care program, we reviewed the interventions recommended to 344 patients referred for the assessment of asthma. A subset of 127 made return visits 6-12 months following their initial assessment, thereby allowing assessment of behavioral and physiological outcomes. At the initial consultation, the recommended medication changes were: inhaled beta-agonists +6% (p < 0.01), inhaled steroids +58% (p < 0.001), intranasal steroids +8% (p < 0.001), dry powdered formulations +13% (p < 0.01), theophylline -7% (p < 0.001). The percentage of patients using spacer devices increased 8% (p < 0.001). Comparing preassessment values to those at a visit at 6-12 months following assessment, a further 25% of patients taking inhaled steroids at the initial assessment had a change to either the dose, device, or frequency of administration. Mean FEV1 improved from 2.41 +/- 0.08 liters at the initial assessment to 2.64 +/- 0.09 liters at the 6-12-month visit (p < 0.001). There was an increase in the number of patients considered mild and not obstructed, with a corresponding decrease in the number considered moderately and severely obstructed (p < 0.05). The number of emergency room visits was reduced by more than 60% (p < 0.001) in patients followed for at least 6 months. We conclude that an ambulatory asthma program marked by increased use of inhaled anti-inflammatory medications and decreased use of theophylline can produce significant decreases in asthma exacerbations requiring hospital care, emergency room care, or systemic steroids while reducing the prevalence and severity of airflow limitation.

Administration, Inhalation↗
PubMed1994

Trends in pharmacotherapy for chronic airflow limitation in Argentina: 1983-1990.

Reported increases in worldwide asthma mortality have prompted the publications of guidelines and consensus statements on the management of airway disease. Overreliance in bronchodilator therapy and lack of anti-inflammatory treatment have been the major findings and the guidelines are aimed at correcting these problems. The Argentinean population appears to have increased prevalence and severity of conditions characterized by chronic airflow limitation and there is no data, to our knowledge, that has analyzed how the treatment of such conditions has been conducted in the past years. Drug sales data in Argentina were surveyed retrospectively to estimate prescriptions dispensed for the treatment of airway disease for the years 1983 to 1990 inclusive. The number of prescriptions of all airway drugs increased significantly (p < 0.01) in the 8-year period except for oral beta 2-agonists and disodium cromoglycate (DSCG). Prescriptions for these agents were 42.7% and 69% less frequent respectively. Thus, oral beta 2-agonists declined from being the single most frequently prescribed class of drugs (40% of prescriptions) in 1983 to the third most frequently prescribed (22%) in 1990. Concurrently, prescriptions of inhaled beta 2-agonists in all forms rose significantly comprising 27% in 1983 and 46% in 1990 becoming the most commonly prescribed airway therapy. Despite this apparent trend away from oral bronchodilator therapy, theophylline prescriptions comprised a significantly higher percentage of prescriptions in 1990 as compared to 1983 (30% vs 20%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1993

Trends in asthma and chronic obstructive pulmonary disease therapy in Canada, 1985 to 1990.

BACKGROUND: In the mid and late 1980s, numerous changes were recommended in the management of obstructive lung diseases. We analyzed drug sales to determine whether these recommendations have resulted in recent changes in prescription drugs used in airway management. METHODS: Data on prescription sales in Canada from 1985 to 1990 were obtained from an international pharmaceutical market research organization. Data from a random sampling of physicians that reported patients seen along with the diagnosis and prescriptions given were also reviewed. RESULTS: From 1985 to 1990, there was a 38% increase in prescriptions of all airway drugs. Prescriptions increased significantly for inhaled drugs as follows: inhaled beta 2-agonists, 70%; inhaled steroids, 139%; cromoglycate, 88%; and ipratropium bromide, 204%. Theophylline prescriptions, by contrast, fell significantly, by 19%. Although theophylline was the most commonly prescribed airway medication in 1985, inhaled beta 2-agonists were the most commonly prescribed drug in 1990, and these changes in proportional use were significant. Increases in ipratropium bromide usage was accounted for by increases in prescriptions for chronic obstructive pulmonary disease. Increases in nonsteroidal antiinflammatory drugs were accounted for by asthma prescriptions. CONCLUSIONS: The increase in airway medication prescriptions dispensed in Canada is consistent with an increase in the number of patients treated, an increase in the severity of disease treated, or both.

Anti-Inflammatory Agents↗
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

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

Physician perceptions and management of COPD.

To assess awareness and understanding of obstructive airway diseases by primary-care physicians, the authors surveyed a randomly selected population of 75 primary care practitioners. During one-on-one interviews, physicians were presented with a standardized case scenario and a subsequent series of open-ended questions concerning asthma and COPD. Each respondent was presented in randomized fashion with one of two versions of a case description of a hypothetical 52-year-old male smoker with a recent upper respiratory tract infection and persistent productive cough. The only difference between case descriptions was that one included explicit reference to an earlier tentative diagnosis of chronic bronchitis (CB version); the other description made no specific mention of this diagnostic term (NCB version). Chest radiographs were requested by 80 percent of physicians and sputum cultures by 50 percent, these percentages not differing significantly between CB and NCB groups. Spirometry was requested less often than either of the foregoing tests (21 percent). The CB group requested spirometry significantly more often than the NCB group (38 percent vs 5 percent, p < 0.05). The most frequently mentioned primary diagnosis was bronchitis/pneumonia (33 percent), followed by bronchitis (28 percent) and chronic bronchitis (16 percent), all of which were similar in both groups. However, the diagnostic term "COPD" was the primary diagnosis in 16 percent of the CB group, compared with 8 percent in the NCB group (p > 0.05). Oral antibiotics were the most frequently chosen first-line drug therapy (63 percent). In subsequent questions concerning the management of obstructive airway diseases, primary practitioners distinguished COPD from asthma conceptually, but their prescribed therapy for the two disorders was less distinct. beta 2-agonists were selected most frequently and similarly as initial therapy for both disorders (53 percent). Minor differences between first-line therapeutic choices included nonsignificant trends toward the more frequent mention of anticholinergic bronchodilators for COPD than for asthma (10 percent vs 0 percent) and the more frequent selection of inhaled corticosteroids for asthma (12 percent vs 5 percent). The authors conclude that to the extent that questionnaire responses reflect actual practice, primary care practitioners (1) have a low index of suspicion for obstructive airway disease, (2) markedly underutilized spirometry as a screening tool, (3) consider beta 2-agonists first-line therapy for COPD and asthma, and (4) despite considering COPD and asthma different disease processes, choose similar medications for each disorder.

Airway Obstruction↗
PubMed1993

A comparison of breath-actuated and conventional metered-dose inhaler inhalation techniques in elderly subjects.

BACKGROUND: Poor coordination of canister actuation and inspiration often prevents adequate metered-dose inhaler (MDI) usage by patients, perhaps especially so among the elderly. Breath-actuated inhalers (BAI) have been developed to prevent this problem. METHODS: We compared the adequacy of inhaler technique and patient preferences between MDI and BAI in a group of elderly subjects (mean age, 70.8 +/- 5.4 years). Half of the subjects were regular MDI users; half had never before used one. Two trained observers assessed the adequacy of MDI and BAI usage subjectively while performance was monitored objectively using a light source and infrared system to detect canister actuation and a spirometer to measure the inspiratory volume. If canister actuation was not followed by at least a 50 percent vital capacity, inhaler use was deemed unsuccessful. A brief teaching session preceded inhaler usage. RESULTS: By subjective assessment, BAI was used successfully more often than MDI (79 vs 60 percent, p < 0.05). By objective assessment, BAI was used successfully more often than MDI (64 vs 36 percent, p < 0.0005), although the percentage of inhalations scored adequate was lower than when assessment was subjective. Neither device was used correctly as often by those unfamiliar with MDIs as by those who were regular users. A significantly higher percentage of patients preferred BAI to MDI (71 vs 19 percent, p < 0.005), similar preferences being reported by MDI familiar and MDI unfamiliar groups. CONCLUSIONS: We conclude that (1) elderly subjects frequently handle inhalers poorly, (2) mishandling is better detected by objective than subjective monitoring, and (3) BAI is used correctly and preferred by patients more often than conventional MDIs.

Administration, Inhalation↗
PubMed1993

Pharmacist knowledge and ability to use inhaled medication delivery systems.

Previous studies have shown that a significant proportion of patients and physicians have difficulty using metered dose inhaler (MDI) delivery systems. It has been suggested that paramedical personnel such as pharmacists could address this problem by serving as patient educators. Few studies have assessed a pharmacist's knowledge of and ability to use inhaled devices, including not only the conventional MDI but newer devices such as an add-on spacing chamber (Aerochamber) and a multidose dry powder inhaler (Turbuhaler). We therefore approached all pharmacists in a predefined geographic area of a large city in order to evaluate their knowledge of and ability to use inhaled medications. Of 62 pharmacists approached, 45 (73 percent) agreed to participate. Ability to use the conventional MDI, Aerochamber (A), and Turbuhaler (T) was graded by a trained observer using a checklist of 11 essential steps. The percentage of pharmacists performing greater than 6, 8, and 10 steps correctly for each device was MDI = 96 percent, 87 percent, 62 percent; MDI + A = 80 percent, 76 percent, 47 percent; T = 67 percent, 64 percent, 29 percent. The most common problems with the MDI were forgetting to shake prior to use and coordinating inspiration with actuation. The most common problems with the MDI + A were forgetting to shake prior to use, remembering to inspire after actuation, and breath holding after inspiration. The most common difficulty with the T was total unfamiliarity with the device with 33 percent of pharmacists achieving less than 2 steps correctly. The observer subsequently administered a questionnaire of 11 clinically relevant questions for each of the devices tested. The mean score was 50 percent with only 21 percent of pharmacists scoring above 70 percent. Thirty-three percent of respondents had no instruction in device use beyond reading the packing insert; 40 percent had received instruction from a pharmaceutical representative; only 24 percent had received instructions from professional school. We conclude that a pharmacist's knowledge of inhaling devices is roughly proportional to the length of time the device has been available and that pharmacists form another group of health care professionals who require further teaching regarding inhaled medication delivery systems.

Asthma↗
PubMed1992

Respiratory interaction after spinal anesthesia and sedation with midazolam.

The combined use of midazolam and spinal anesthesia is common in clinical practice. Despite the known potential for each to alter ventilation, the effect of their interaction has not been examined. Nineteen healthy volunteers were studied to assess the impact of intravenous midazolam (0.05 or 0.075 mg/kg), spinal anesthesia (T3-T8; mean level, T6), and their combination on resting ventilation and ventilatory responses to progressive hyperoxic hypercapnia. Resting ventilatory pattern was altered significantly by each condition. Midazolam caused a 29% decrease in resting tidal volume and a 24% decrease in mean inspiratory flow rate, while respiratory frequency increased by 14% and minute ventilation remained unchanged. By contrast, spinal anesthesia alone caused a 32% increase in tidal volume, a 24% increase in mean inspiratory flow rate, and a 13% increase in minute ventilation accompanied by a 14% decrease in respiratory frequency. The combination of midazolam and spinal anesthesia caused a significant decrease in minute ventilation (19%), tidal volume (28%), and mean inspiratory flow rate (27%), all of which were significantly more than the predicted sum of the individual interventions. Midazolam and spinal anesthesia each produced a significant decrease in hypercapnic ventilatory response slope, whereas their combination provoked no net change in hypercapnic ventilatory response slope. Interpretation of the hypercapnic ventilatory response data was complicated by shifts in the position of the ventilatory response curve, particularly under the spinal anesthesia condition. It is concluded that intravenous midazolam depresses resting ventilation, spinal anesthesia stimulates resting ventilation, and their combination has a modest synergistic effect of depressing resting ventilation.

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↗