Practitioners often use a severity scale that divides COPD exacerbations into three categories, the panel reported. These categories include:

• Type 1: Increased dyspnea, sputum volume, and sputum purulence.

• Type 2: Two of the three type-1 symptoms.

• Type 3: One type-1 symptom and at least one of the following: upper respiratory infection within the past five days, fever with no other cause, increased wheezing or cough, or a 20% rise over baseline in respiratory or heart rate.

While the scale’s validity is limited—based only on response to antibiotic treatment—“it is the best scale out there,” said Dr. McCrory, an Assistant Professor in the Evidence-Based Practice Center at Duke University School of Medicine in Durham, North Carolina, which developed the report for AHRQ.

Admission chest films are useful in acute COPD because they often precipitate a change in management, the panel found. However, there was insufficient evidence to permit firm conclusions about the best way to detect deep vein thrombosis, which frequently accompanies COPD exacerbations.

Due to the poor correlation between forced expiratory volume in one second (FEV1) and arterial blood gases (ABGs), spirometry should play only a limited role in assessing acute COPD. “Clinically, this poor correlation … means that the spirometric measure cannot obviate the need for ABG measurement in patients presenting with acute exacerbation of COPD,” the panel explained in the report.

Although advanced age and intravenous fluid administration, among other factors, have been linked to a worsening of COPD exacerbations, no predictive model accurately forecasts patient outcomes, such as hospitalization, relapse, the need for mechanical ventilation, or mortality. Therefore, emphasized the panel, ongoing clinical monitoring often is necessary in patients with acute COPD.

A small improvement in these patients’ pulmonary function occurs with antibiotic treatment; the drugs studied included tetracycline, doxycycline, chloramphenicol, ampicillin, amoxicillin, co-trimoxazole, and a penicillin-streptomycin combination. Antibiotics seem to be most beneficial in those with evidence of bacterial infection (eg, sputum purulence) or more severe illness (as indicated by peak expiratory flow). This has not been conclusively proved, however.

Narrow-spectrum antibiotics appear to be reasonable first-line agents for acute COPD; existing randomized, controlled trials have not established the superiority of the newer broad-spectrum antibiotics. However, “these studies are old, making them difficult to interpret in a world where we now have many resistant organisms,” Dr. Bach cautioned.

Bronchodilators are also effective for COPD exacerbations; however, the panel found no difference in effectiveness between ß2-agonists and anticholinergics. Further, adding one of these drugs after achieving maximum bronchodilation with the other did not appear to produce an incremental increase in efficacy. Methylxanthines were found to be less effective bronchodilators than either of the other two drug classes, and they were associated with a higher rate of adverse reactions.

For patients who need hospitalization for COPD exacerbations, two weeks of systemic corticosteroids is preferable to eight weeks, several good trials have suggested. The most well known of these trials is the Systemic Corticosteroids in Chronic Obstructive Pulmonary Disease Exacerbations (SCCOPE) Trial, which found similar FEV1 improvements and decreases in treatment-failure risk among acute COPD inpatients randomized to two or eight weeks of systemic methylprednisolone.[2]

Adverse side effects were less common with the shorter regimen, the trial also showed. However, the optimal dose and duration of systemic corticosteroids for acute COPD remains unclear, the panel noted. Further, inhaled corticosteroids have not been adequately tested in patients with this condition.

Though laborious, noninvasive positive pressure ventilation (NPPV) is sometimes an effective alternative to mechanical ventilation in patients with acute respiratory failure secondary to a COPD exacerbation. For best results, patients must be conscious and able to tolerate the use of the NPPV apparatus. However, those with rapidly deteriorating respiratory status, as indicated by a pH below 7.3, are candidates for immediate intubation and mechanical ventilation.

Typically, NPPV is better tolerated and thus more effective if patients get the type of mask (nasal or face) that maximizes their comfort. The same applies to the ventilator mode. Pressure support ventilation and continuous or bi-level positive airway pressure modes appear to be best tolerated. Generally, the assist-control mode with NPPV is poorly tolerated unless the volume and rate are adjusted to the individual patient.

Three common acute COPD therapies—mucolytics, chest physiotherapy, and methylxanthines—are probably not recommended, said Dr. Bach, because they seem to lack benefit and may even be harmful. Furthermore, mucolytics do not change symptom duration or severity.

--Timothy Begany

References
1. Evidence Report/Technology Assessment Number 19: Evidence Report on Management of Acute Exacerbations of COPD. Rockville, Md: Agency for Healthcare Research and Quality, US Dept of Health and Human Services; in press. AHRQ publication 00-R050.

2. Erbland ML, Deupree RH, Niewoehner DE. Systemic Corticosteroids in Chronic Obstructive Pulmonary Disease Exacerbations (SCCOPE): rationale and design of an equivalence trial. Veterans Administration Cooperative Trials SCCOPE Study Group. Control Clin Trials. 1998;19:404-417.