CHICAGO-New guidelines for management of pneumothorax were previewed at Chest 1999, the Annual Meeting of the American College of Chest Physicians (ACCP). What prompted the ACCP to commission the guidelines was the marked heterogeneity in current practice patterns, said Michael H. Baumann, MD, a coauthor of the guidelines.

CURRENT PRACTICE VARIES WIDELY

The extent of variation in the treatment of spontaneous pneumothoraces and recurrences was demonstrated in 1997 by a survey(1) conducted by Dr. Baumann, associate professor of medicine, pulmonary disease, and critical care medicine at the University of Mississippi Medical School, and Charlie Strange, MD, associate professor of medicine, pulmonary disease, and critical care medicine at the Medical University of South Carolina and a coauthor of the new guidelines. The table below lists six common clinical scenarios and the disparate treatment approaches of the nearly 350 practicing pulmonologists, academic pulmonologists, and thoracic surgeons surveyed.

One reason for the practice variation is the general lack of data from randomized clinical trials. The medical literature contains only eight trials that address issues related to spontaneous pneumothorax management, Dr. Baumann noted. Despite this lack of attention, spontaneous pneumothorax is a common problem. About 20,000 new cases occur each year in the United States(2,3); the associated health care costs are estimated at $130 million annually.(4)

In the absence of clinical data, the new ACCP practice guidelines were developed using the Delphi technique. This is a questionnaire-based process that allows anonymity in responses and thus eliminates opinion bias. The resulting consensus statement reflects the views of 32 international experts, including pulmonologists, thoracic surgeons, emergency department physicians, and radiologists.

The expert panel graded management options for various clinical scenarios on a scale that ranged from extremely appropriate (a first-line therapy) to extremely inappropriate (a never-used therapy). The degree of consensus on each strategy was also assessed. Thus, what clinicians will find in the guidelines, expected to be published this spring in Chest, is a series of management definitions that rate options as:

• preferred management in most cases
  
• acceptable management in most cases, only in certain circumstances, or rarely
  
• inappropriate management.

Factors that affected the consensus panel's choice of a management strategy included the size of the pneumothorax and clinical stability of the patient. Interestingly, neither the duration of symptoms nor patient age influenced therapy selection.

PRIMARY PNEUMOTHORAX MAY WARRANT NEW APPROACH

For a patient with a small primary spontaneous pneumothorax who is clinically stable, simple observation in the emergency department and discharge after 3 to 6 hours is often sufficient, the new guidelines suggest. In addition to the initial diagnostic chest film, a radiograph should be obtained before discharge and during a follow-up visit, usually 12 to 48 hours after discharge, to ensure the clinical stability of the patient. However, if the patient is not likely to be compliant with follow-up or does not have ready access to transportation, admission may be advisable.

With such strategies, the expert panel demonstrated good consensus. Less definitive consensus was achieved concerning the preferred management approach for a clinically stable patient with a large primary spontaneous pneumothorax. The trend was toward preferring a more aggressive approach, with hospital admission and either simple aspiration with a small-bore catheter and placement of a Heimlich valve or chest tube insertion. Chest tube placement and admission were favored for the patient with a large pneumothorax who is clinically unstable, however.

Pleurodesis via a chest tube was not preferred for most patients with a persistent primary spontaneous pneumothorax. Surgical intervention-most experts favored thoracoscopy-was generally reserved for patients with an air leak, but after only 4 days of observation, a shorter period than the 5 to 10 days allotted in current practice.

Another important management decision addressed in the guidelines is the size of the chest tube. Airflow through the tube is primarily determined by the internal radius of the tube-specifically, by radius to the fifth power. Even a small incremental decrease in the size of the chest tube produces a logarithmic reduction in the amount of airflow that the tube can handle, Dr. Baumann emphasized. Thus, the larger tubes, 24 F to 28 F, are preferred for patients at high risk for an air leak, whereas smaller tubes, even those less than 14 F, may be used safely in patients at low risk.

After a chest tube is in place, how should the physician proceed? The consensus group favored initially attaching the tube to a water seal; tube attachment to a Heimlich valve was considered a less desirable option. Suction, in the expert panel's opinion, should be reserved for patients with a persistent pneumothorax. This staged approach marks a shift from the current practice of attaching the tube to suction immediately, the approach used by 48% of the physicians in the 1997 survey.(1)

What is the preferred chest tube removal sequence? How long should the physician wait after the air leak has stopped? Is clamping necessary before tube removal? Again, the expert panel preferred a staged approach to ensure that no air leak is present: stopping the suction, continuing the water seal while monitoring the patient closely for the air leak, obtaining a follow-up chest film to confirm lung inflation, and then removing the tube 5 to 12 hours after evidence of an air leak was last seen. No clear consensus emerged regarding clamping.

Ideally, the goal of therapy for spontaneous pneumothorax is not just to eliminate air from the pleural space and to terminate an air leak, if one is present, but also to prevent recurrence. However, patients with a primary spontaneous pneumothorax are at low risk for recurrence. Prevention becomes increasingly important after the second occurrence (ie, the first recurrence). Thoracoscopy was the procedure preferred by the expert panel.

SECONDARY PNEUMOTHORAX INCREASES RISKS

Unlike primary spontaneous pneumothorax, which has no clear precipitating factor, secondary spontaneous pneumothorax usually occurs as a complication of lung disease. Chronic obstructive pulmonary disease (COPD) is the most common underlying disorder, although pneumonias related to the acquired immunodeficiency syndrome or to mycobacterial infection also are often responsible. The guidelines pertain to patients with secondary pneumothorax associated with COPD. However, many of the recommendations are relevant to patients with secondary pneumothoraces associated with other underlying lung disorders.

Current practice in managing secondary pneumothorax is more homogeneous than that in treating primary pneumothorax, Dr. Strange noted. Chest tube placement has been the first-line therapy. However, the expert panel recognized observation of small secondary pneumothoraces as an acceptable alternative for patients who are clinically stable. The key difference in the management approaches for small primary and secondary pneumothoraces is that the latter requires hospital admission.

Observation is not an option for patients with a large secondary pneumothorax or those who are clinically unstable; chest tube placement and admission are preferred. The trend is against using the Heimlich valve in this setting. A patient with a secondary pneumothorax who is at risk for an air leak or bronchopleural fistula will likely need a larger chest tube than would a patient with a primary pneumothorax.

Staged approaches are recommended for chest tube attachment and removal in patients with a secondary spontaneous pneumothorax. Once again, this represents a departure from current practice. Particularly in the setting of secondary pneumothorax, suctioning may increase the risk of an air leak. The key difference from primary pneumothorax management is that 13 to 23 hours should elapse between the last evidence of an air leak and chest tube removal.

Patients with secondary spontaneous pneumothorax are at increased risk (40%) for recurrence. A trend toward initiating recurrence prevention (preferably via thoracoscopy) after the first, rather than after the second, occurrence was noted. Pleural abrasion and bullectomy stood out as the most favored operative procedures.

-Christine M. Olsen, PhD

References
1. Baumann MH, Strange C. The clinician's perspective on pneumothorax management. Chest. 1997;112:822-828.
2. Baumann MH, Strange C. Treatment of spontaneous pneumothorax: a more aggressive approach? Chest. 1997;112:789-804.
3. Melton LJ 3d, Hepper NG, Offord KP. Incidence of spontaneous pneumothorax in Olmsted County, Minnesota: 1950-1974. Am Rev Respir Dis. 1979;120:1379-1382.
4. Bense L, Wiman LG, Jendteg S, Lindgren B. Economic costs of spontaneous pneumothorax [letter]. Chest. 1991;99:260-261.

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