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The value of chest roentgenography in the diagnosis of pneumothorax after thoracentesis∗
The Value of Chest Roentgenography in the Diagnosis of Pneumothorax after Thoracentesis* Carmen Alema´n, MD, Jose´ Alegre, MD, Lluı´s Armadans, MD, Jordi Andreu, MD, Vicenc¸ Falco´, MD, Jesu´s Recio, MD, Carlos Cervera, MD, Eva Ruiz, MD, Toma´s Ferna´ndez de Sevilla, MD PURPOSE: We sought to assess the yield of chest roentgenography for the detection of pneumothorax among hospitalized patients with pleural effusion who have undergone diagnostic or therapeutic thoracentesis. SUBJECTS AND METHODS: We performed a prospective study of 506 thoracentesis procedures in 370 patients. After the procedure, each operator filled out a note recording patient data and the characteristics of the thoracentesis. A chest radiograph was performed within 12 hours after the procedure in all patients. RESULTS: Eighteen (4%) pneumothoraces occurred in 17 patients, 9 (2%) of which required chest tube drainage. Of the 488
patients without symptoms, only 5 (1%) developed a pneumothorax, only 1 of which required chest tube drainage. By contrast, of the 18 patients with symptoms, 13 developed a pneumothorax, 8 of which required chest tubes. There were two independent predictors of pneumothorax: presence of symptoms (odds ratio [OR] ⫽ 250; 95% confidence interval [CI]: 65 to 980) and male gender (OR ⫽ 5.4; 95% CI: 1.9 to 69). CONCLUSIONS: Among the symptom-free patients in our sample, the risk of developing pneumothorax with clinical consequences was so low that the practice of routine chest roentgenography may not be justified. Am J Med. 1999;107: 340 –343. 䉷1999 by Excerpta Medica, Inc.
M
lona. When several thoracenteses were performed in a single patient on different days, all were evaluated. After the procedure, the operator completed a note recording the patient data, including age, gender, previous thoracic surgery or thoracic radiation, presence of bullae, other pathologic findings, and the size of the pleural effusion on chest radiograph; and thoracentesis characteristics, including operator experience, use of fine needle catheter, number of needle passes required to obtain the fluid, ultrasound guidance, side of the procedure, clinical indication (diagnostic or therapeutic), evidence of air aspira-
ost patients who are admitted to the hospital with pleural effusion undergo diagnostic or therapeutic thoracentesis. Various complications have been associated with this procedure, the most frequent of which is pneumothorax, with a reported incidence between 3% to 20% (1– 4). Although a posteroanterior chest radiograph is usually performed after thoracentesis to detect a pneumothorax, this practice involves considerable expense, and its potential benefits have not been established. Our concern over the optimal use of hospital resources prompted us to begin a prospective study in October 1992 to evaluate the need for routine chest roentgenography after thoracentesis. Our aim was to assess the yield of chest radiographs and to determine whether there are clinical characteristics that are associated with the presence of pneumothorax in these patients.
SUBJECTS AND METHODS From October 1992 to March 1997, 506 consecutive thoracentesis procedures were performed in 370 patients at the Vall d’Hebron General Teaching Hospital in Barce* Access the “Journal Club” discussion of this paper at http://www. elsevier.com/locate/ajmselect/ From the Services of Internal Medicine (CA, JA, VF, JR, CC, ER, TFS), Preventive Medicine and Epidemiology (LA), and Radiology (JA), Hospital General Vall d’Hebron, Universitat Auto´noma, Barcelona, Spain. Supported in part by the FISS grant:98/0747. Requests for reprints should be addressed to Dr. Carmen Alema´n, C/Co´rcega 469 2⬚ 1a, 08025 Barcelona, Spain. Manuscript submitted December 23, 1998, and accepted in revised form June 4, 1999. 340
䉷1999 by Excerpta Medica, Inc. All rights reserved.
Table 1. Selected Clinical Characteristics and Radiological Findings in 370 Patients Who Underwent Thoracentesis Characteristic
Number (Percent)
Male gender Smoker Previous thoracic radiation Previous thoracic surgery Radiographic findings Bullae Bronchiectasis Lung cancer Other Normal parenchyma Etiology of pleural effusions Empyema Parapneumonic Tuberculous Malignant Transudate Miscellaneous Unknown etiology
221 (60%) 214 (58%) 13 (4%) 22 (6%) 6 (1%) 5 (1%) 34 (10%) 52 (14%) 273 (74%) 42 (11%) 40 (11%) 58 (16%) 50 (14%) 60 (16%) 19 (5%) 101 (27%)
0002-9343/99/$–see front matter PII S0002-9343(99)00238-7
Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
Table 2. Characteristics of 506 Thoracentesis Procedures Characteristic
Number (Percent)
Right-sided procedure Size of pleural effusion ⬍1/3 of lung field 1/3 to 2/3 of lung field ⬎2/3 of lung field Procedure Diagnostic Therapeutic ⬍1000 cc Therapeutic ⬎1000 cc Experience of physician Junior resident Senior resident or staff Number of needle passes 1 2 or 3 4 or more Size of needle Fine Catheter Ultrasound-guided thoracentesis
279 (55%) 191 (38%) 209 (41%) 106 (21%) 340 (67%) 69 (14%) 97 (19%) 344 (68%) 162 (32%) 408 (81%) 87 (17%) 11 (2%) 490 (96%) 16 (4%) 23 (5%)
tion, and presence of symptoms during and after thoracentesis. All patients underwent chest roentgenography within 12 hours after the procedure, and all chest radiographs were reviewed blindly by one radiologist to maintain consistency of interpretation.
Statistical Analysis The unit of analysis for procedure-related characteristics was the thoracentesis; the patient was the analytical unit for patient-related characteristics. Odds ratios were calculated for each categorical condition to estimate the relative risk of developing a pneumothorax. The two-sample t test was used to compare the ages of patients who developed a pneumothorax with those who did not (5). A stratified analysis was performed according to the Mantel-Haenszel method. The Epi Info program (version 6.03) was used to estimate the adjusted odds ratios and their 95% confidence intervals CI) (6).
RESULTS Five hundred and six thoracenteses were evaluated in 370 patients with a mean (⫾ SD) age of 59 ⫾ 21 years (range 16 to 98). Data from the patients are shown in Table 1, and the characteristics of the thoracenteses are shown in Table 2. Eighteen pneumothoraces occurred in 17 (4%) patients, 9 of which required chest tube drainage. There were no deaths directly related to the procedure. The treating clinician suspected that a pneumothorax had occured, based on air being aspirated during the procedure, in only 3 (1%) patients. Pneumothorax was suspected based on the presence of symptoms in 18 (4%) patients (cough in 1, dyspnea in 4, pleuritic chest pain in 8, and combinations of these symptoms in 5). In unadjusted analyses, there were two patient characteristics associated with pneumothorax: male sex and bullae on the chest radiograph (Table 3). There were three procedure-related predictors related to the thoracentesis in unadjusted analyses: aspiration of air during the procedure, therapeutic (rather than diagnostic) indication for the thoracentesis, and presence of symptoms during or after the procedure (Table 4). In stratified analyses, only male gender and presence of symptoms during or after the procedure remained as independent predictors. Of the 488 patients without symptoms, only 5 (1%) developed a pneumothorax, only 1 of which required a chest tube. By contrast, of the 18 patients with symptoms, 13 developed a pneumothorax, 8 of which required chest tubes (Figure). Thus, 13 of the 18 pneumothoraces and 8 of the 9 requiring chest tube drainage could have been predicted. If chest radiographs had been obtained only in those patients with symptoms, 488 studies would have been avoided, and only 1 severe pneumothorax would have escaped early identification. The symptom-free patient who required insertion of a chest tube was an 81-year-old man who had lung cancer and a massive malignant pleural effusion and who presented with dyspnea. Therapeutic thoracentesis was performed and 1900 cc pleural fluid
Table 3. Risk of Developing Pneumothorax by Selected Patient-Related Characteristics
Characteristic
Number with Pneumothorax/ Number with Characteristic (%)
Number with Pneumothorax/ Number without Characteristic (%)
Odds Ratio (95% Confidence Interval)
P Value
Age ⬍50 years Male gender Current smoker Previous thoracic surgery Previous thoracic irradiation Bullae
7/122 (6%) 15/221 (7%) 6/214 (3%) 1/22 (4%) 0/13 (0%) 2/6 (33%)
10/248 (4%) 2/149 (1%) 11/156 (7%) 16/348 (5%) 17/340 (5%) 15/364 (4%)
1.5 (0.5 to 4) 5.4 (1.2 to 24) 0.4 (0.1 to 1.1) 1 (0.1 to 8.3) 0 (0 to 7.2) 12 (1.9 to 69)
0.6 0.03 0.09 1 ⬎0.65 0.002
October 1999
THE AMERICAN JOURNAL OF MEDICINE威
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Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
Table 4. Risk of Developing Pneumothorax by Procedure-Related Characteristics
Characteristic Ultrasound-guided thoracentesis Malignant effusion Right-sided thoracentesis Size of pleural effusion ⬍1/3 of lung field Therapeutic indication Experience of operator ⬍2 years Thoracentesis catheter Two or more passes Air aspirated Symptoms
Number with Pneumothorax/ Number with Characteristic (%)
Number without Pneumothorax/ Number with Characteristic (%)
Odds Ratio (95% Confidence Interval)
P Value
1/23 (4%)
17/483 (4%)
1.2 (0.1 to 9.8)
0.6
2/50 (4%) 10/279 (4%) 5/191 (3%)
16/456 (3%) 8/227 (4%) 13/315 (4%)
1.2 (0.3 to 5.1) 1 (0.1 to 2.6) 0.6 (0.2 to 1.8)
0.7 1 0.5
11/166 (7%) 16/344 (5%)
7/340 (2%) 2/162 (1%)
3.4 (1.3 to 8.9) 3.9 (0.9 to 17)
0.02 0.09
0/16 (0%) 2/98 (2%) 2/3 (67%) 13/18 (72%)
18/490 (4%) 16/408 (4%) 1/503 (0.2%) 5/488 (1%)
0 (0 to 7.5) 0.5 (0.1 to 2.3) 61 (5.2 to 710) 250 (65 to 980)
⬎0.66 0.5 0.004 ⬍0.001
Figure. Decision tree showing the risk of unsuspected pneumothorax if chest roentgenography was obtained only in patients with symptoms during or after thoracentesis. 342
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Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
was removed. The patient improved clinically, but the postthoracentesis chest radiograph disclosed a tension pneumothorax. The pneumothoraces in the other 4 symptom-free patients were small and resolved spontaneously.
DISCUSSION Several studies have documented that thoracentesis is associated with iatrogenic pneumothorax (7,8). Routine chest roentgenography for early detection of potential pneumothorax is commonly performed on all patients who undergo thoracentesis. However, the actual benefit of this practice has not been established. In our prospective study, a chest radiograph was obtained within 12 hours after the procedure on all patients who underwent diagnostic or therapeutic thoracentesis. The reported incidence of pneumothorax after thoracentesis in previous studies has ranged from 3% to 20%, 20% to 50% of which needed chest tube drainage (1– 4,8 –11). We found a somewhat lower incidence of pneumothorax (4%), half of which required chest tube drainage. Only male gender and presence of symptoms during and after the thoracentesis were independent predictors of pneumothorax. Other authors have also found that the development of procedure-related symptoms is associated with iatrogenic pneumothorax (12,13). That male gender was also an independent predictor of pneumothorax was unexpected, and we cannot offer an explanation: multivariate analyses excluded associations with chronic obstructive disease or other abnormalities on chest radiographs. Other reports have found associations between pneumothorax and the clinical indication for thoracentesis, chronic obstructive pulmonary disease, and the aspiration of air during the procedure (4,10,12,13). However, none of these factors was an independent predictor of pneumothorax in our study. Pneumothorax has also been related to a history of previous thoracic surgery or irradiation, lung cancer (12,13), needle size (1,4), number of passes required to obtain a sample (12), experience of the operator (1,2,13–16), loculated effusion (16), and the size of the effusion (4,16). We did not find an association with any of these factors. The incidence of pneumothorax after ultrasoundguided thoracentesis is not certain (1,3,4,17). Although our data on this are limited (the 23 guided thoracenteses were small effusions, and two or more passes had been tried without obtaining pleural fluid), our experience indicated that a blind attempt probably does not increase the incidence of pneumothorax.
Since only one critical pneumothorax was found in a patient without symptoms in our study of 506 episodes, we recommend that chest radiographs be performed after thoracentesis only in patients with symptoms. If these criteria had been applied to our sample, we would have avoided 488 radiographs with virtually no changes in patient management and with considerable savings of hospital resources.
ACKNOWLEDGMENT The authors thank Celine Cavallo for linguistic advice.
REFERENCES 1. Grogan DR, Irwin RS, Channick R, et al. Complications associated with thoracentesis. A prospective randomised study comparing three different methods. Arch Intern Med. 1990;150:873– 877. 2. Seneff MG, Corwin RW, Gold LH, Irwin RS. Complications associated with thoracentesis. Chest. 1986;90:97–100. 3. Roth M, Hal Cragun LTC, Grathwohl CPT. Complications associated with thoracentesis. Arch Intern Med. 1991;151:2095–2096. 4. Raptopoulus V, Davis L, Lee G, et al. Factors affecting the development of pneumothorax associated with thoracentesis. AJR. 1991; 156:917–920. 5. SPSS for Windows. Release 6.0. Chicago, IL: SPSS Inc. 1993. 6. Dean AG, Dean JA, Coulombier D, et al. Epi Info, Version 6. A Word-Processing, Database, and Statistics Program for Public Health on IBM-compatible Microcomputers.Atlanta, Ga: Centers for Disease Control and Prevention; 1995. 7. Sassoon C, Light R, O’Hara V, Mortiz T. Iatrogenic pneumothorax: etiology and morbidity. Respiration. 1992;59:215–220. 8. Despars J, Sassoon C, Light R. Significance of iatrogenic pneumothorax. Chest. 1994;105:1147–1150. 9. Collins TR, Sahn SA. Thoracentesis. Clinical value, complications, technical problems, and patient experience. Chest. 1987;91:817– 822. 10. Brandetter R, Karetzky M, Rastogi R, Lolis J. Pneumothorax after thoracentesis in chronic obstructive pulmonary disease. Heart Lung. 1994;23:67–70. 11. Qureshi N, Momin Z, Brandsetter R. Thoracentesis in clinical practice. Heart Lung. 1994;23:376 –383. 12. Doyle J, Hnatiuk O, Torrington K. Necessity of routine chest roentgenography after thoracentesis. Ann Intern Med. 1996;124:816 – 820. 13. Gerardi D, Scalise P, Lahiri B. The utility of the routine post-thoracentesis chest radiograph. Chest. 1994;106:83S. Abstract. 14. Swinburne A, Bixby K, Fedullo A, et al. Pneumothorax after thoracentesis. Arch Intern Med. 1991;151:2095. 15. Bartter T, Mayo PD, Pratter MR, et al. Lower risk and higher yield for thoracentesis when performed by experienced operators. Chest. 1993;103:1873–1876. 16. Schiffman P, Brunswick N. Complications of thoracentesis. Arch Intern Med. 1990;150:2598 –2599. 17. Koohan J, Poe R, Israel R, et al. Value of chest ultrasonography versus decubitus roentgenography for thoracentesis. Am Rev Respir Dis. 1986;133:1124 –1126.
October 1999
THE AMERICAN JOURNAL OF MEDICINE威
Volume 107 343
patients without symptoms, only 5 (1%) developed a pneumothorax, only 1 of which required chest tube drainage. By contrast, of the 18 patients with symptoms, 13 developed a pneumothorax, 8 of which required chest tubes. There were two independent predictors of pneumothorax: presence of symptoms (odds ratio [OR] ⫽ 250; 95% confidence interval [CI]: 65 to 980) and male gender (OR ⫽ 5.4; 95% CI: 1.9 to 69). CONCLUSIONS: Among the symptom-free patients in our sample, the risk of developing pneumothorax with clinical consequences was so low that the practice of routine chest roentgenography may not be justified. Am J Med. 1999;107: 340 –343. 䉷1999 by Excerpta Medica, Inc.
M
lona. When several thoracenteses were performed in a single patient on different days, all were evaluated. After the procedure, the operator completed a note recording the patient data, including age, gender, previous thoracic surgery or thoracic radiation, presence of bullae, other pathologic findings, and the size of the pleural effusion on chest radiograph; and thoracentesis characteristics, including operator experience, use of fine needle catheter, number of needle passes required to obtain the fluid, ultrasound guidance, side of the procedure, clinical indication (diagnostic or therapeutic), evidence of air aspira-
ost patients who are admitted to the hospital with pleural effusion undergo diagnostic or therapeutic thoracentesis. Various complications have been associated with this procedure, the most frequent of which is pneumothorax, with a reported incidence between 3% to 20% (1– 4). Although a posteroanterior chest radiograph is usually performed after thoracentesis to detect a pneumothorax, this practice involves considerable expense, and its potential benefits have not been established. Our concern over the optimal use of hospital resources prompted us to begin a prospective study in October 1992 to evaluate the need for routine chest roentgenography after thoracentesis. Our aim was to assess the yield of chest radiographs and to determine whether there are clinical characteristics that are associated with the presence of pneumothorax in these patients.
SUBJECTS AND METHODS From October 1992 to March 1997, 506 consecutive thoracentesis procedures were performed in 370 patients at the Vall d’Hebron General Teaching Hospital in Barce* Access the “Journal Club” discussion of this paper at http://www. elsevier.com/locate/ajmselect/ From the Services of Internal Medicine (CA, JA, VF, JR, CC, ER, TFS), Preventive Medicine and Epidemiology (LA), and Radiology (JA), Hospital General Vall d’Hebron, Universitat Auto´noma, Barcelona, Spain. Supported in part by the FISS grant:98/0747. Requests for reprints should be addressed to Dr. Carmen Alema´n, C/Co´rcega 469 2⬚ 1a, 08025 Barcelona, Spain. Manuscript submitted December 23, 1998, and accepted in revised form June 4, 1999. 340
䉷1999 by Excerpta Medica, Inc. All rights reserved.
Table 1. Selected Clinical Characteristics and Radiological Findings in 370 Patients Who Underwent Thoracentesis Characteristic
Number (Percent)
Male gender Smoker Previous thoracic radiation Previous thoracic surgery Radiographic findings Bullae Bronchiectasis Lung cancer Other Normal parenchyma Etiology of pleural effusions Empyema Parapneumonic Tuberculous Malignant Transudate Miscellaneous Unknown etiology
221 (60%) 214 (58%) 13 (4%) 22 (6%) 6 (1%) 5 (1%) 34 (10%) 52 (14%) 273 (74%) 42 (11%) 40 (11%) 58 (16%) 50 (14%) 60 (16%) 19 (5%) 101 (27%)
0002-9343/99/$–see front matter PII S0002-9343(99)00238-7
Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
Table 2. Characteristics of 506 Thoracentesis Procedures Characteristic
Number (Percent)
Right-sided procedure Size of pleural effusion ⬍1/3 of lung field 1/3 to 2/3 of lung field ⬎2/3 of lung field Procedure Diagnostic Therapeutic ⬍1000 cc Therapeutic ⬎1000 cc Experience of physician Junior resident Senior resident or staff Number of needle passes 1 2 or 3 4 or more Size of needle Fine Catheter Ultrasound-guided thoracentesis
279 (55%) 191 (38%) 209 (41%) 106 (21%) 340 (67%) 69 (14%) 97 (19%) 344 (68%) 162 (32%) 408 (81%) 87 (17%) 11 (2%) 490 (96%) 16 (4%) 23 (5%)
tion, and presence of symptoms during and after thoracentesis. All patients underwent chest roentgenography within 12 hours after the procedure, and all chest radiographs were reviewed blindly by one radiologist to maintain consistency of interpretation.
Statistical Analysis The unit of analysis for procedure-related characteristics was the thoracentesis; the patient was the analytical unit for patient-related characteristics. Odds ratios were calculated for each categorical condition to estimate the relative risk of developing a pneumothorax. The two-sample t test was used to compare the ages of patients who developed a pneumothorax with those who did not (5). A stratified analysis was performed according to the Mantel-Haenszel method. The Epi Info program (version 6.03) was used to estimate the adjusted odds ratios and their 95% confidence intervals CI) (6).
RESULTS Five hundred and six thoracenteses were evaluated in 370 patients with a mean (⫾ SD) age of 59 ⫾ 21 years (range 16 to 98). Data from the patients are shown in Table 1, and the characteristics of the thoracenteses are shown in Table 2. Eighteen pneumothoraces occurred in 17 (4%) patients, 9 of which required chest tube drainage. There were no deaths directly related to the procedure. The treating clinician suspected that a pneumothorax had occured, based on air being aspirated during the procedure, in only 3 (1%) patients. Pneumothorax was suspected based on the presence of symptoms in 18 (4%) patients (cough in 1, dyspnea in 4, pleuritic chest pain in 8, and combinations of these symptoms in 5). In unadjusted analyses, there were two patient characteristics associated with pneumothorax: male sex and bullae on the chest radiograph (Table 3). There were three procedure-related predictors related to the thoracentesis in unadjusted analyses: aspiration of air during the procedure, therapeutic (rather than diagnostic) indication for the thoracentesis, and presence of symptoms during or after the procedure (Table 4). In stratified analyses, only male gender and presence of symptoms during or after the procedure remained as independent predictors. Of the 488 patients without symptoms, only 5 (1%) developed a pneumothorax, only 1 of which required a chest tube. By contrast, of the 18 patients with symptoms, 13 developed a pneumothorax, 8 of which required chest tubes (Figure). Thus, 13 of the 18 pneumothoraces and 8 of the 9 requiring chest tube drainage could have been predicted. If chest radiographs had been obtained only in those patients with symptoms, 488 studies would have been avoided, and only 1 severe pneumothorax would have escaped early identification. The symptom-free patient who required insertion of a chest tube was an 81-year-old man who had lung cancer and a massive malignant pleural effusion and who presented with dyspnea. Therapeutic thoracentesis was performed and 1900 cc pleural fluid
Table 3. Risk of Developing Pneumothorax by Selected Patient-Related Characteristics
Characteristic
Number with Pneumothorax/ Number with Characteristic (%)
Number with Pneumothorax/ Number without Characteristic (%)
Odds Ratio (95% Confidence Interval)
P Value
Age ⬍50 years Male gender Current smoker Previous thoracic surgery Previous thoracic irradiation Bullae
7/122 (6%) 15/221 (7%) 6/214 (3%) 1/22 (4%) 0/13 (0%) 2/6 (33%)
10/248 (4%) 2/149 (1%) 11/156 (7%) 16/348 (5%) 17/340 (5%) 15/364 (4%)
1.5 (0.5 to 4) 5.4 (1.2 to 24) 0.4 (0.1 to 1.1) 1 (0.1 to 8.3) 0 (0 to 7.2) 12 (1.9 to 69)
0.6 0.03 0.09 1 ⬎0.65 0.002
October 1999
THE AMERICAN JOURNAL OF MEDICINE威
Volume 107 341
Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
Table 4. Risk of Developing Pneumothorax by Procedure-Related Characteristics
Characteristic Ultrasound-guided thoracentesis Malignant effusion Right-sided thoracentesis Size of pleural effusion ⬍1/3 of lung field Therapeutic indication Experience of operator ⬍2 years Thoracentesis catheter Two or more passes Air aspirated Symptoms
Number with Pneumothorax/ Number with Characteristic (%)
Number without Pneumothorax/ Number with Characteristic (%)
Odds Ratio (95% Confidence Interval)
P Value
1/23 (4%)
17/483 (4%)
1.2 (0.1 to 9.8)
0.6
2/50 (4%) 10/279 (4%) 5/191 (3%)
16/456 (3%) 8/227 (4%) 13/315 (4%)
1.2 (0.3 to 5.1) 1 (0.1 to 2.6) 0.6 (0.2 to 1.8)
0.7 1 0.5
11/166 (7%) 16/344 (5%)
7/340 (2%) 2/162 (1%)
3.4 (1.3 to 8.9) 3.9 (0.9 to 17)
0.02 0.09
0/16 (0%) 2/98 (2%) 2/3 (67%) 13/18 (72%)
18/490 (4%) 16/408 (4%) 1/503 (0.2%) 5/488 (1%)
0 (0 to 7.5) 0.5 (0.1 to 2.3) 61 (5.2 to 710) 250 (65 to 980)
⬎0.66 0.5 0.004 ⬍0.001
Figure. Decision tree showing the risk of unsuspected pneumothorax if chest roentgenography was obtained only in patients with symptoms during or after thoracentesis. 342
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Volume 107
Chest Roentgenography in Diagnosing Pneumothorax after Thoracentesis/Alema´n et al
was removed. The patient improved clinically, but the postthoracentesis chest radiograph disclosed a tension pneumothorax. The pneumothoraces in the other 4 symptom-free patients were small and resolved spontaneously.
DISCUSSION Several studies have documented that thoracentesis is associated with iatrogenic pneumothorax (7,8). Routine chest roentgenography for early detection of potential pneumothorax is commonly performed on all patients who undergo thoracentesis. However, the actual benefit of this practice has not been established. In our prospective study, a chest radiograph was obtained within 12 hours after the procedure on all patients who underwent diagnostic or therapeutic thoracentesis. The reported incidence of pneumothorax after thoracentesis in previous studies has ranged from 3% to 20%, 20% to 50% of which needed chest tube drainage (1– 4,8 –11). We found a somewhat lower incidence of pneumothorax (4%), half of which required chest tube drainage. Only male gender and presence of symptoms during and after the thoracentesis were independent predictors of pneumothorax. Other authors have also found that the development of procedure-related symptoms is associated with iatrogenic pneumothorax (12,13). That male gender was also an independent predictor of pneumothorax was unexpected, and we cannot offer an explanation: multivariate analyses excluded associations with chronic obstructive disease or other abnormalities on chest radiographs. Other reports have found associations between pneumothorax and the clinical indication for thoracentesis, chronic obstructive pulmonary disease, and the aspiration of air during the procedure (4,10,12,13). However, none of these factors was an independent predictor of pneumothorax in our study. Pneumothorax has also been related to a history of previous thoracic surgery or irradiation, lung cancer (12,13), needle size (1,4), number of passes required to obtain a sample (12), experience of the operator (1,2,13–16), loculated effusion (16), and the size of the effusion (4,16). We did not find an association with any of these factors. The incidence of pneumothorax after ultrasoundguided thoracentesis is not certain (1,3,4,17). Although our data on this are limited (the 23 guided thoracenteses were small effusions, and two or more passes had been tried without obtaining pleural fluid), our experience indicated that a blind attempt probably does not increase the incidence of pneumothorax.
Since only one critical pneumothorax was found in a patient without symptoms in our study of 506 episodes, we recommend that chest radiographs be performed after thoracentesis only in patients with symptoms. If these criteria had been applied to our sample, we would have avoided 488 radiographs with virtually no changes in patient management and with considerable savings of hospital resources.
ACKNOWLEDGMENT The authors thank Celine Cavallo for linguistic advice.
REFERENCES 1. Grogan DR, Irwin RS, Channick R, et al. Complications associated with thoracentesis. A prospective randomised study comparing three different methods. Arch Intern Med. 1990;150:873– 877. 2. Seneff MG, Corwin RW, Gold LH, Irwin RS. Complications associated with thoracentesis. Chest. 1986;90:97–100. 3. Roth M, Hal Cragun LTC, Grathwohl CPT. Complications associated with thoracentesis. Arch Intern Med. 1991;151:2095–2096. 4. Raptopoulus V, Davis L, Lee G, et al. Factors affecting the development of pneumothorax associated with thoracentesis. AJR. 1991; 156:917–920. 5. SPSS for Windows. Release 6.0. Chicago, IL: SPSS Inc. 1993. 6. Dean AG, Dean JA, Coulombier D, et al. Epi Info, Version 6. A Word-Processing, Database, and Statistics Program for Public Health on IBM-compatible Microcomputers.Atlanta, Ga: Centers for Disease Control and Prevention; 1995. 7. Sassoon C, Light R, O’Hara V, Mortiz T. Iatrogenic pneumothorax: etiology and morbidity. Respiration. 1992;59:215–220. 8. Despars J, Sassoon C, Light R. Significance of iatrogenic pneumothorax. Chest. 1994;105:1147–1150. 9. Collins TR, Sahn SA. Thoracentesis. Clinical value, complications, technical problems, and patient experience. Chest. 1987;91:817– 822. 10. Brandetter R, Karetzky M, Rastogi R, Lolis J. Pneumothorax after thoracentesis in chronic obstructive pulmonary disease. Heart Lung. 1994;23:67–70. 11. Qureshi N, Momin Z, Brandsetter R. Thoracentesis in clinical practice. Heart Lung. 1994;23:376 –383. 12. Doyle J, Hnatiuk O, Torrington K. Necessity of routine chest roentgenography after thoracentesis. Ann Intern Med. 1996;124:816 – 820. 13. Gerardi D, Scalise P, Lahiri B. The utility of the routine post-thoracentesis chest radiograph. Chest. 1994;106:83S. Abstract. 14. Swinburne A, Bixby K, Fedullo A, et al. Pneumothorax after thoracentesis. Arch Intern Med. 1991;151:2095. 15. Bartter T, Mayo PD, Pratter MR, et al. Lower risk and higher yield for thoracentesis when performed by experienced operators. Chest. 1993;103:1873–1876. 16. Schiffman P, Brunswick N. Complications of thoracentesis. Arch Intern Med. 1990;150:2598 –2599. 17. Koohan J, Poe R, Israel R, et al. Value of chest ultrasonography versus decubitus roentgenography for thoracentesis. Am Rev Respir Dis. 1986;133:1124 –1126.
October 1999
THE AMERICAN JOURNAL OF MEDICINE威
Volume 107 343