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COPD is a complex mix of signs and symptoms in patients with chronic bronchitis and emphysema, diseases that largely result from cigarette smoking. Not all smokers, however, acquire COPD, and COPD can develop in nonsmokers. In the United States, COPD is currently the fourth leading cause of death. Surprisingly, there are no effective drug therapies for COPD that are able to significantly alter disease progression, and little is known of the underlying molecular mechanisms that are responsible for its occurrence. Candidate gene-association studies and linkage analyses have been reported for COPD patients. This review describes the genetic predisposition of healthy subjects or relatives of COPD patients to acquire COPD. In addition, the genetic bases of COPD with rapid decline of FEV1 are described, and the current genetic data that have been distilled from studies of COPD patients with a predominant emphysema phenotype, with chronic bronchitis phenotype, and with a response to bronchodilators are discussed.

We studied 12 fatality-prone patients for 18 months after they had been discharged from the hospital following life-threatening exacerbations of asthma (mean PaCO2 on admission, 97 mm Hg). Our objectives were (1) to evaluate the natural history of their disease during ambulatory care and (2) to investigate whether close follow-up might help to avert further near-fatal events. Only seven of the 12 patients consented to be enrolled in the study, which included monthly scheduled visits to the hospital and monthly telephone calls to record emergency room visits and changes in therapy. By the conclusion of the 18-month follow-up period, two of the noncompliant patients had died during asthmatic attacks. By contrast, all of the seven who had agreed to participate survived; one required intubation and mechanical ventilation, and the other six required occasional unscheduled emergency room visits because of acute exacerbations. Specific precipitants could not be determined, and the most common cause of the acute episodes was likely inadequate steroid therapy. The results suggest that compliance with adequate antiasthmatic therapy and close follow-up may be important in the prevention of near-fatal events.

Despite the increasing use of dry powder formulations in the ambulatory setting, there is a paucity of information on the efficacy of this therapeutic modality to treat acute severe asthma. In addition, studies that compared wet nebulization vs metered dose inhalers formulated with chlorofluorocarbon (CFCMDI) attached to holding chambers have yielded discrepant results. Thus, it is unclear which of the three delivery systems would elicit a superior bronchodilator response, particularly in patients with life-threatening asthma. In a prospective, randomized open design, we studied the response to inhaled albuterol (salbutamol) in 27 adult asthmatics presenting to the emergency department (ED) with an FEV130% predicted. Subjects were treated with one of the following regimens (nine subjects in each group): group A, mean (SD) baseline FEV1 of 0.7 (0.2) L, received albuterol solution, 5 mg, via a nebulizer (Puritan-Bennett Raindrop; Lawrenceville, Ga) impelled with oxygen (O2) at 8 L/min; group B, baseline FEV1 of 0.6 (0.15) L, received albuterol, 400 microg, via a CFCMDI attached to a 145-mL valved aerosol holding chamber (Aerochamber; Trudell Medical; London, ON); and group C, baseline FEV1 of 0.6 (0.17) L, received albuterol powder, 400 microg, by another means (Rotahaler; Glaxo; Research Triangle Park, NC). All groups received the respective treatments on arrival in the ED, every 30 min during the first 2 h, and then hourly until the sixth hour. Clinical parameters and FEV1 were recorded on ED admission and 15 min after each dose of albuterol. At the time of ED admission, all patients also received continuous O2 and one dose of I.V. steroids (dexamethasone, 8 mg). The total dose of inhaled albuterol administered during the 6-h treatment was 45 mg of nebulized solution in group A and 3,600 microg of albuterol aerosol and dry powder in groups B and C, respectively. No significant differences were found in the population demographics, baseline FEV1, and arterial blood gas values on air. FEV1 improved significantly in all patients after the 6 h of treatment. The 6-h area under the curve FEV1 improved similarly with the three delivery methods despite differences in the total dose administered. No patient was discontinued during the trial or admitted to hospital and no evidence of cardiovascular adverse events was apparent in any of the study groups. These data support the view that the three delivery methods appear adequate to treat subjects with acute severe asthma.

Background It has been suggested that overuse of fenoterol metered-dose inhalers (MDIs) may increase the risk of death from asthma due to cardiac arrhythmias. Our primary objective was to compare the cardiovascular safety of fenoterol and albuterol MDIs when administered in maximal bronchodilating or maximal tolerated doses to an absolute maximum of 16 puffs, for the emergency department (ED) treatment of acute severe asthma. Methods Asthmatic patients presenting to the ED with acute severe asthma (FEV 1 less than 50% of predicted) were enrolled in a multi-center, randomized, double-blind, parallel-group study. Following baseline measurements, (medical history, physical examination, determination of serum potassium and serum theophylline levels, oximetry, 12-lead ECG, and spirometry), each patient received 4 puffs of either fenoterol, 200 µg per puff, or albuterol, 100 µg per puff, 1 puff every 30 s via an MDI attached to a holding chamber. Additional doses of inhaled β 2 -agonist were administered by dose titration, 2 puffs every 10 min to a maximal cumulative dose of 16 puffs of albuterol or fenoterol, side effects were intolerable to the patient, or an FEV 1 plateau ( ie , >10% improvement for 2 consecutive doses) occurred. ECG was recorded continuously via Holter monitor, and respiratory rate, BP, dyspnea (Borg scale), and FEV 1 were assessed after each dose. Results 128 patients were randomized to receive fenoterol and 129 to receive albuterol. Overall, fenoterol increased FEV 1 160 mL more than albuterol. The mean (SEM) FEV 1 increase from baseline was 0.75±0.06 L in the fenoterol group and 0.59±0.06 L in the albuterol group (p>0.03). Both β2-agonists caused a decrease in serum potassium level that was significantly greater in the fenoterol (0.23±0.04 mmol/L) than in the salbutamol (0.06±0.03 mmol/L) group (p=0.0002). There was also a greater increase in the Q-Tc interval in the fenoterol group, 0.011±0.003 s compared with 0.003±0.003 s in the albuterol group (p>0.05). Differences in hypokalemia and Q-Tc prolongation associated with fenoterol and albuterol were significantly different only after 8 puffs of fenoterol had been given. 32 patients exhibited ventricular premature beats, 14 in the fenoterol group and 18 in the albuterol group. There were 34 patients with episodes of supraventricular premature beats, 17 in each group. No episodes of sustained ventricular tachycardia were detected in either group. Conclusions In adequately oxygenated patients, using dose titration of fenoterol, in a formulation of 200 µg per puff by MDI valved holding chamber and mask, to a total dose of 3,200 µg and salbutamol (100 µg per puff) to a total dose of 1,600 µg over 90 min, showed cardiovascular safety in acute severe asthma. This was evidenced by absence of cardiovascular mortality or clinically significant arrhythmias in either group. The 100% greater dose of fenoterol improved FEV 1 significantly more than salbutamol and was associated with a relatively small but significantly greater prolongation of the Q-Tc interval and decrease in serum potassium level. This study does not exclude the possibility that adverse cardiac events could occur with severe hypoxemia. (CHEST 1996; 110:595-603)

Although it is well known that isocapnic hyperventilation (IHV) with dry cold air produces airway constriction in asthmatic subjects, the site of airway narrowing is nuclear. To address this issue, we have quantified the tracheal and bronchial response to IHV with dry cold air in 15 patients with mild asthma and 7 healthy control subjects. We employed the acoustic reflection technique to evaluate changes in airway cross-sectional areas caused by IHV with dry cold air. Airway areas were measured during tidal breathing before and 5 to 10, 30, 60, and 90 min following cold air challenge. For analysis purposes, airway areas were divided into three anatomic segments: extrathoracic tracheal segment, intrathoracic tracheal segment, and main bronchial segment. These segments were assessed at a fixed volume below total lung capacity. Maximal and partial expiratory flow-volume curves were also obtained before each set of area measurements. In normal subjects, IHV with dry cold air caused no significant changes in FEV1, flow at 30% of the vital capacity in the partial curve (V30p), or airway areas. In asthmatics, at 5 to 10 min after challenge, we found that FEV1 decreased by 22 +/- 5% (mean +/- SEM) (p0.0001), V30p by 33 +/- 8% (p0.003), intrathoracic tracheal area by 10.7% +/- 2% (p0.03), and main bronchial area by 14 +/- 3% (p0.003). At 30 min, tracheal and main bronchial areas were returned to baseline levels; however, FEV1 and V30p were still significantly decreased, by 13 +/- 3% and 16 +/- 4%, respectively. We conclude that in asthmatics, IHV with dry cold air causes both tracheal and bronchial constriction, and that recovery seems to occur first in the central airways.