Pneumothorax

trials.2– 4 It could lead to more accurate drug labeling and stimulate the development of pharmaceutical products that are truly effective and functional. Elizabeth Koller, MD Saul Malozowski, MD, PhD Steven Johnson, PharmD Rockville, MD

pliant patients could in fact be related to discomfort with discussing compliance issues with study personnel. We can only speculate, however, on what the motivation for dumping may be. Because clinical trials are generally not designed to study questions of this type, future studies that focus on the motivations for compliance and deceptive practices among participants in clinical trials are needed. Michael S. Simmons Donald P. Tashkin, MD, FCCP UCLA School of Medicine Los Angeles, CA

Correspondence to: Elizabeth Koller, MD, 5600 Fishers Lane, Parklawn Building, Room 14B04, Rockville, MD 20857

References 1 Simmons MS, Nides MA, Rand CS, et al. Unpredictability of deception in compliance with physician-prescribed bronchodilator inhaler use in a clinical trial. Chest 2000; 118:290 –295 2 Enstrom I, Pennert K, Lindholm LH. Durability of improvement achieved in a clinical trial: is compliance an issue? J Fam Pract 2000; 498:634 – 637 3 Li BD, Brown WA, Ampil FL, et al. Patient compliance is critical for equivalent clinical outcomes for breast cancer treated by breast-conservation therapy. Ann Surg 2000; 231: 883– 889 4 Crim C. Clinical practice guidelines vs actual clinical practice: the asthma paradigm. Chest 2000; 118(2 suppl):62S– 64S To the Editor: The correspondents raise some interesting questions regarding our report1 (August 2000) on compliance in the Lung Health Study, as well as the importance of future investigations in this field. The 10-center Lung Health Study was not initially designed for the purpose of investigating compliance issues, as they correctly point out. While the ancillary study on which our article is based was designed to study compliance at the two centers at which electronic medication monitors were used, some constraints and limitations were necessarily posed by the design and organization of the parent study. The patients’ motivation for entering our study cannot be determined with certainty, but no medical treatment was promised or provided except for the interventions specified in the study protocol. Possible incentives included the smoking cessation program (one half of all participants) and bronchodilator inhalers (one third of all participants received active bronchodilator inhalers). Because most participants did not have any serious or disabling symptoms (asthmatics were excluded) and no medical treatment was promised, we believe that the bronchodilator inhaler was not a motivating factor for most subjects to enter the study. We feel the promise of pulmonary function testing and the possibility of assistance with smoking cessation were the primary motivations for patient participation. The nature of the relationship between study participants and the investigators was not described in our article but, in fact, patients of study investigators were excluded from the study to avoid conflict of interest. There are no data on the patients’ medical insurance coverage or their previous participation in other clinical trials, although concurrent participation in non-Lung Health Study clinical trials was not permitted. Study participants were asked about their bronchodilator inhaler use at each clinic visit. When poor compliance was revealed, they were queried about possible causes, including difficulties in scheduling or remembering their inhaler use, as well as any problems they may have had with the medication itself. Because the intent was to improve compliance with the study medication, free discussion was encouraged and we believe participants were comfortable discussing the use of their inhalers with clinic personnel. A notable exception, of course, would be the “dumpers” who denied problems with compliance. The motivation behind dumping in this interesting subset of noncom1292

Correspondence to: Michael S. Simmons, UCLA, Division of Pulmonary and Critical Care, Los Angeles, CA 90095-1690; e-mail: [email protected]

Reference 1 Simmons MS, Nides MA, Rand CS, et al. Unpredictability of deception in compliance with physician-prescribed bronchodilator inhaler use in a clinical trial. Chest 2000; 118:290 –295

Pneumothorax Is Chest Tube Clamp Necessary Before Removal? To the Editor: I read with interest the study, “Pneumothorax: Experience With 1,199 Patients” (May 2000).1 While the discussion part of the article was thorough and informative, the statement that the pleural drain should be removed without clamping after the cessation of air leak needs further exploration. As the choice of therapeutic procedure varies according to the number of episodes, the size of pneumothorax, and the particular group of investigators, chest tube removal should also be dependent on the underlying lung disease, the presence or absence of bronchopleural fistula, the history of pneumothorax, and the severity of the initial episode. Primary spontaneous pneumothorax has been viewed as lowmortality nuisance.2 Chest tubes may be removed as soon as the lung expands and air leak ceases. In the presence of underlying lung disease or when pneumothorax has been associated with bronchopleural fistula, it is always imperative to clamp the tube for a variable duration before it is removed. Many physicians also agree that the chest tube should be clamped before it is finally removed.3– 6 Similar is the recommendation in the Light textbook on pleural diseases.7 An analysis on pneumothorax management performed by Baumann and Strange8 also verifies the above view, where at least 67% of the responders suggested chest tube clamping for a period varying from 4 to 24 h. Another 27% in their study preferred to wait for at least 24 h after the air leak stopped before the chest tube was removed, although they did not prefer a clamp. Similar was the authors’ approach in the present study,1 but they ultimately suggested not to wait or clamp the tube. In my experience, it is not uncommon to observe a relapse of pneumothorax after removal of chest tube as soon as the lung expands or air leak ceases. I would also like to mention an Indian study9 performed by my senior colleagues, in which they observed that the early removal (6 h) of the chest tube after complete expansion of the lung results in a greater relapse rate than removal after 48 h. The onset of breathlessness at a variable time after a clamp would definitely indicate more prolonged chest tube drainage. Communications to the Editor

The discomfort caused by such a clamp for 24 h would be lesser than a second chest tube insertion after relapse. If the chest tube was not working (no water column movement and no air leak) overnight, then it may be considered as good as a clamp, and it may be removed if the lung is completely expanded clinically and radiologically. In my opinion, a clamp for 12 to 24 h before removal of the drain is one aspect of authors’ view of patience in the management of pneumothorax. How could a chest tube be dangerous in a patient with a possible tension pneumothorax? Once the chest tube is clamped and if the patient suddenly develops breathlessness, the only thing to do is to remove the clamp and observe the vital parameters closely. In fact, for the case of a clamped chest tube, the patient and duty staff should be asked about the measures to be taken as soon as breathlessness precipitates. If the symptoms of tension pneumothorax may develop after a clamp, then why not on removal of the chest drain? This point needs further clarification. Neeraj Gupta, MD Ajmer, India Correspondence to: Neeraj Gupta, MD, Government Doctors Quarters, Type III, Opposite Fire Station, Near Ajmer Club, Ajmer - 305001, (Rajasthan) India; e-mail: [email protected]

References 1 Weissberg D, Refaely Y. Pneumothorax: experience with 1,199 patients. Chest 2000; 117:1279 –1285 2 Baumann MH, Strange C. Treatment of spontaneous pneumothorax: a more aggressive approach? Chest 1997; 112:789 – 804 3 Andrivet P, Djedaini K, Teboul JL, et al. Spontaneous pneumothorax: comparison of chest drainage vs immediate or delayed needle aspiration. Chest 1995; 108:335–339 4 Schoenenberger RA, Haefeli WE, Weiss P, et al. Timing of invasive procedures in therapy for primary and secondary spontaneous pneumothorax. Arch Surg 1991; 126:764 –766 5 Schoenenberger RA, Haefeli WE, Weiss P, et al. Evaluation of conventional chest tube therapy for iatrogenic pneumothorax. Chest 1993; 104:1770 –1772 6 So S, Yu D. Catheter drainage of spontaneous pneumothorax: suction or no suction, early or late removal? Thorax 1982; 37:46 – 48 7 Light RW. Pleural diseases. 3rd ed. Baltimore, MD: Williams & Wilkins, 1995; 242–277 8 Baumann MH, Strange C. The clinician’s perspective on pneumothorax management. Chest 1997; 112:822– 828 9 Sharma TN, Agnihotri SP, Jain NK, et al. Intercostal tube thoracostomy in pneumothorax. Indian J Chest Dis Allied Sci 1988; 30:32–35 To the Editor: I appreciated the opportunity to read the comments of Dr. Gupta on our report (May 2000) on pneumothorax.1 Dr. Gupta objected to our policy of removing the pleural drain without clamping it for a number of hours. Also, he implied incorrectly that we remove the drain immediately after the drainage stops, without waiting for 24 h. In support of his preference to clamp the tube, he quoted several authors who favor clamping. With your permission, I would like to quote some others, who do not clamp.2– 6 However, this controversy cannot be solved by a democratic referendum. The decision “to clamp or not to clamp” must be clinically sound and based on experience, not on voting. There is no logic in clamping a tube that has not drained anything for a number of hours. When drainage stops, we leave the drain for 24 h prior to removal. However, as a clamped tube serves no purpose, it should be left unclamped. While some pulmonologists

and thoracic surgeons may be in favor of clamping, there is no scientific evidence to support it. Dov Weissberg, MD, FCCP E Wolfson Medical Center Holon, Israel Correspondence to: Dov Weissberg, MD, FCCP, Department of Thoracic Surgery, E Wolfson Medical Center, Holon 58100, Israel

References 1 Weissberg D, Refaely Y. Pneumothorax: experience with 1,199 patients. Chest 2000; 117:1279 –1285 2 Belcher JR, Sturridge MF. Thoracic surgical management, 4th ed. London, UK: Bailliere Tindall, 1972; 154 –158 3 von Hippel A. A manual of thoracic surgery. Springfield, IL: Charles C. Thomas, 1978; 112 4 Gregoire J, Deslauriers J. Closed drainage and suction systems. In: Pearson FG, Deslauriers J, Ginsberg RJ, et al, eds. Thoracic surgery. New York, NY: Churchill Livingstone, 1995; 1126 5 Martin T, Fontana G, Olak J, et al. Use of a pleural catheter for the management of simple pneumothorax. Chest 1996; 110:1169 –1172 6 Hatz RA, Kaps MF, Meimarakis G, et al. Long-term results after video-assisted thoracoscopic surgery for first-time and recurrent spontaneous pneumothorax. Ann Thorac Surg 2000; 70:253–257

CT Scanning and Bilateral Surgery for Unilateral Primary Pneumothorax? To the Editor: I read with great interest the article (August 2000) by Sihoe and coworkers1 on the predictive role of CT scanning on the risk of occurrence of primary spontaneous pneumothorax (PSP). I was particularly amazed in the finding that the detection of lung blebs or bullae by CT scan in the contralateral lung of patients with PSP was significantly correlated with the risk of occurrence of PSP in that lung. Indeed, there is—to my knowledge—no unequivocal evidence that rupture of blebs or bullae is actually the cause of PSP; blebs and bullae may in fact be considered also as “innocent bystanders” of the disease process that will eventually lead to PSP.2 Therefore, I recalculated the statistics given by Sihoe et al1: they found that 4 of 15 patients with contralateral blebs developed PSP in that lung (26.7%), whereas none of the 13 patients who did not have contralateral blebs developed PSP, a difference that was considered statistically significant (p ⫽ 0.04, ␹2 analysis). However, when recalculating the data on the basis of the proposed contingency table, I found the ␹2 statistic to be nonsignificant: ␹2 ⫽ 2.160 with one degree of freedom (p ⫽ 0.142; Table 1)! Furthermore, in this situation, one should use a correction for the fact that the frequency in at least one cell of the table is ⬍ 5,

Table 1—Contingency Table Based on the Data by Sihoe et al1 Variables

Blebs

No Blebs

Total

Occurrence of pneumothorax No occurrence of pneumothorax Totals

4 11 15

0 13 13

4 24 28

CHEST / 119 / 4 / APRIL, 2001

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