- Email: [email protected]
Can preoperative imaging studies accurately predict the occurrence of bullae or blebs? Correlation between preoperative radiological and intraoperative findings
respiratory investigation 51 (2013) 224 –228
Contents lists available at ScienceDirect
Respiratory Investigation journal homepage: www.elsevier.com/locate/resinv
Original article
Can preoperative imaging studies accurately predict the occurrence of bullae or blebs? Correlation between preoperative radiological and intraoperative findings Takeshi Kawaguchia,b,n, Keiji Kushibea, Motoaki Yasukawaa, Norikazu Kawaia a
Department of Thoracic Surgery, Nara Prefectural Nara Hospital, Japan Department of Thoracic and Cardiovascular Surgery, Nara Medical University School of Medicine, Japan
b
ar t ic l e in f o
abs tra ct
Article history:
Background: Radiological findings of patients with primary spontaneous pneumothorax
Received 28 December 2012
(PSP) undergoing surgery have not been well analyzed. The aim of this study was to
Received in revised form
evaluate the accuracy of imaging studies for predicting the presence of emphysema-like
27 March 2013
changes (ELCs) detectable during surgery.
Accepted 19 April 2013
Methods: Ninety-three PSP patients who underwent surgery from September 2005 to
Available online 5 June 2013
October 2009 were included in the study. We analyzed preoperative chest radiographic
Keywords:
and computed tomographic (CT) findings, and compared the findings with intraoperative
Pneumothorax
detection of ELCs. Chest radiographic findings were analyzed by classifying the PSP size
VATS
into three categories: small, moderate, and complete.
Chest CT
Results: Seventy-six of the 93 patients (82%) had ELCs detected during surgery. The size of
Chest radiography
the PSP on a radiograph was significantly correlated with the presence of ELCs (p¼0.0121). Preoperative CT revealed 64 of the 76 ELCs (sensitivity, 84%; specificity, 100%; accuracy, 87%). Twenty-nine patients without ELCs detected by preoperative CT were analyzed separately. In this group, a larger PSP size also increased the likelihood of ELCs being present (p¼0.0049). Seven patients (8%) experienced a recurrence after surgery. No factor could significantly predict recurrence. Conclusions: Chest CT analysis alone was associated with a false-negative rate of about 15% for ELCs. Combining the analysis of chest radiographic and CT findings could improve sensitivity. & 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.
1.
Introduction
The most common cause of primary spontaneous pneumothorax (PSP) is the rupture of bullae or blebs, which are known as emphysema-like changes (ELCs) [1]. Although the
cause of ELCs is not clear, most patients with PSP have these lesions in their affected lungs, and have them excised if they undergo surgical treatment [2–5]. However, 9–29% of patients undergoing surgery for PSP do not have ELCs, and these patients have a lower postoperative cure rate [2,3,6].
n
Corresponding author at: Department of Thoracic and Cardiovascular Surgery, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan. Tel.: +81 744 22 3051; fax: +81 744 24 8040. E-mail addresses: [email protected] (T. Kawaguchi), [email protected] (K. Kushibe), [email protected] (M. Yasukawa), [email protected] (N. Kawai). 2212-5345/$ - see front matter & 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.resinv.2013.04.004
respiratory investigation 51 (2013) 224 –228
Intraoperative findings are important for determining the surgical procedure performed and for predicting the prognosis [7], but the usefulness of preoperative imaging studies in PSP patients is unclear. According to guidelines for the management of PSP [8,9], routine chest computed tomography (CT) is not recommended, because it is not useful for predicting the recurrence of pneumothorax, identifying the cause of a persistent air leak, or deciding the type of surgical intervention. Chest CT is only recommended when aberrant tube placement is suspected, to differentiate a pneumothorax from complex bullous lung disease, or to evaluate pulmonary disorders in cases of secondary pneumothorax. In clinical practice, however, PSP patients often undergo chest CT to screen for ELCs. The aim of this retrospective study was to evaluate the accuracy of the findings of imaging studies taken prior to pneumothorax surgery. We reviewed patients who underwent surgery for PSP, analyzed their preoperative chest radiographic and CT findings, and compared these findings with the intraoperative findings.
2.
Materials and methods
2.1.
Evaluation items
Ninety-three PSP patients who underwent surgery from September 2005 to October 2009 were included in this study. The indications for surgery were prolonged air leakage or repeated pneumothorax, which is basically in line with the recent guidelines [8,9]. Patients with secondary pneumothorax or recurrent PSP after the surgery were excluded from this analysis. PSP patients who did not undergo preoperative chest CT were also excluded. The patients who underwent bilateral surgery were analyzed separately for each side. Preoperative chest radiographic and CT images were retrospectively reviewed for all patients included in the study. The size of the PSP before drainage was categorized according to its appearance on chest radiography: (1) small: the visceral pleura was separated from the chest wall along
225
only part of the pleural space (Fig. 1a); (2) moderate: the visceral pleura was completely separated from the parietal pleura from the base to the apex, but without total lung collapse (Fig. 1b); and (3) complete: the airless lung was separated from the diaphragm (Fig. 1c). We also evaluated ELCs on high-resolution CT scans performed after the reexpansion of the affected lung (Fig. 2). All patients were treated using video-assisted thoracoscopic surgery (VATS) under general anesthesia with singlelung ventilation. Three ports were placed: one in the fourth intercostal space (ICS) at the anterior axillary line, one in the fifth ICS at the posterior axillary line, and one in the seventh ICS at the mid-axillary line. Although most operations were completed with VATS, extension of a port site was necessary for dissection of a pleuropulmonary adhesion or critical location of the targeted area in four patients. When ELCs were identified, these were excised using an endoscopic stapler. If no ELC was identified, the most suspicious areas, such as those with pleuropulmonary adhesions or minute pleural changes, were removed using an endoscopic stapler
Fig. 2 – Emphysema-like change on high-resolution computed tomography after re-expansion of the affected lung.
Fig. 1 – Size of primary spontaneous pneumothorax according to chest radiography. (a) Small, (b) moderate and (c) complete.
226
respiratory investigation 51 (2013) 224 –228
(mostly in the apex of the affected lung). Staple lines were covered with polyglycolic acid felt with fibrin glue in all patients. One patient did not have a suspicious lesion and only underwent placement of the polyglycolic acid felt. In six patients, additional mechanical pleurodesis was performed by scrubbing the parietal pleura. An intercostal drain was placed at the end of the procedure in all patients, and was removed when there was no longer any air leak. After discharge, all patients underwent at least two further chest radiographies during the follow-up care. Recurrence was defined as a further pneumothorax occurring after the end of treatment.
2.2.
3.
Results
3.1.
Patient characteristics
Patient characteristics are shown in Table 1. Approximately 50% of the patients (47%, 44/93) were classified as having a complete collapse. ELCs were detected in 64 patients (68%, 64/93) by preoperative chest CT, and in 76 patients during surgery (82%, 76/93). The postoperative pneumothorax recurrence rate was 8% (7/93).
3.2. Comparison of preoperative imaging studies and intraoperative findings
Statistical analysis
Univariate analyses were performed using the Mann–Whitney U test and χ2 test. Statistical significance was set at po0.05. Table 1 – Patient characteristics. Characteristics
Number
Age (years) Mean7standard deviation
32716
Sex Male Female
74 19
Size of PSP by chest radiography Small Moderate Complete
24 25 44
Presence of ELC by chest CT Yes No
64 29
Surgical procedure Wedge resection with coverage Wedge resection with coverage and pleurodesis Coverage and pleurodesis without resection
86 6 1
Intraoperative detection of ELC Yes No
76 17
Recurrence of PSP Yes No
7 86
Correlations between the size of the PSP in the chest radiographic and intraoperative findings are shown in Table 2. The size of the PSP was significantly correlated with the presence of ELCs (p ¼0.0121). Correlations between preoperative CT and intraoperative findings are shown in Table 3. Although 64 of the 76 ELCs were detected by preoperative chest CT, 12 were missed (sensitivity, 84%; specificity, 100%; accuracy, 87%). Subsequently, the 29 patients without ELCs on CT were analyzed separately. In this group, a larger PSP size on chest radiography was also significantly correlated with the presence of ELCs (p¼ 0.0049, Table 4).
3.3. Patients with subsequent recurrence of PSP after surgery Seven patients experienced a recurrent pneumothorax after surgery, and their details are shown in Table 5. Five of the seven patients had targeted ELCs during surgery. The χ2 test showed that no factor could significantly predict recurrence
CT: computed tomography; PSP: primary spontaneous pneumothorax; ELC: emphysema-like change.
Table 3 – Correlations between preoperative CT and intraoperative findings in all patients (n ¼93). Intraoperative detection of ELC Yes (n ¼ 76) ELC detection by chest CT Yes (n ¼64) 64 No (n ¼ 29) 12
No (n ¼17)
0 17
CT: computed tomography; ELC: emphysema-like change.
Table 2 – Correlations between the size of the PSP and intraoperative findings. p Value
Intraoperative detection of ELC
Size of PSP according to chest radiography Small (n ¼ 24) Moderate (n ¼ 25) Complete (n ¼44)
Yes (n ¼76)
No (n ¼17)
15 21 40
9 4 4
PSP: primary spontaneous pneumothorax; ELC: emphysema-like change.
0.0121
227
respiratory investigation 51 (2013) 224 –228
Table 4 – Correlations between the size of the PSP and intraoperative findings in patients without ELCs by CT (n ¼ 29). p Value
Intraoperative detection of ELC
Size of PSP according to chest X-ray Small (n ¼10) Moderate (n ¼6) Complete (n ¼13)
Yes (n ¼ 12)
No (n ¼17)
1 2 9
9 4 4
0.0049
PSP: primary spontaneous pneumothorax; ELC: emphysema-like change; CT: computed tomography.
Table 5 – Patients with subsequent recurrence of PSP after surgery.
Case Case Case Case Case Case Case
1 2 3 4 5 6 7
Radiographic finding
CT finding
Intraoperative finding
Complete Moderate Moderate Moderate Moderate Complete Complete
ELC ELC ELC ELC ELC ELC ELC
ELC ELC ELC ELC ELC ELC ELC
(−) (+) (+) (−) (−) (−) (+)
(+) (+) (+) (−) (−) (+) (+)
PSP: primary spontaneous pneumothorax; CT: computed tomography; ELC: emphysema-like change.
(size of PSP: p ¼0.8986; CT finding: p ¼0.1231; intraoperative findings: 0.4638).
4.
Discussion
A diagnosis of PSP is usually made on the basis of the clinical history and is confirmed by chest radiography. Although every patient with PSP underwent chest radiography, the radiological findings of PSP patients have not been well analyzed. It has been reported that chest CT findings have no prognostic value [10–13]. Radiological examination findings therefore do not usually influence treatment choices in patients with PSP [8,9]. However, intraoperative findings have been reported to correlate with postoperative morbidity and recurrence, and are known to predict outcomes after PSP surgery [2,3,6,7,14]. Most patients with PSP undergo chest CT to screen for ELCs. In the present analysis, intraoperative identification of ELCs was compared with preoperative identification of ELCs by using chest radiographic and chest CT findings. First, the size of the PSP evaluated by chest radiography was significantly correlated with the presence of ELCs. Second, not every ELC was detected by chest CT. Although most ELCs were detected by chest CT in this study, 12 detectable lesions (16%, 12/76) were missed. The accuracy rate may be improved by combining chest CT with chest radiographic analysis. In patients without ELCs detected on chest CT, greater lung collapse on radiography increased the likelihood of ELCs being present. Possible reasons for the false-negative chest CT findings may be related to the size and location of the lesions, or to the collapse of lesions. ELCs are generally predominant in the lung apex [1]. Evaluation of a small low-attenuation area at
the apex is sometimes difficult due to the variety of lung parenchymal and pleural changes seen in this region [3]. False-negative results are inevitable when only chest CT findings are evaluated. Our analysis did not identify any factor predictive of recurrent PSP after surgery. Intraoperative detection of ELCs also had no predictive value for recurrence. It may be that our sample size was too small for such a rare event. According to recent guidelines [9,10], surgery is indicated in patients with repeated ipsilateral PSP, first contralateral PSP, bilateral PSP, PSP with persistent air leak, hemothorax, and an at-risk profession. With advances in video thoracoscopic equipment, most surgeries to treat PSP are performed via VATS, which is less invasive and has outcomes similar to open thoracotomy [16,17]. Based on its minimal invasiveness and cosmetic advantage, some reports have recommended surgery for patients experiencing their first episode of PSP [18,19]. However, the recurrence rate associated with the VATS approach is higher than that of the open approach [20]. Based on the guideline recommendations, patients and clinicians make medical decisions considering the potential risk of recurrence, the invasiveness of the treatment, and the treatment outcome, among other factors. ELCs are the main targets of surgery to correct PSP. Furthermore, patients with ELCs who undergo surgery for PSP also have a good prognosis [2,3,6]. Therefore, precise prediction of ELCs as surgical targets influences clinical decision-making.
5.
Conclusions
In this study, preoperative chest radiographic and CT findings were compared with intraoperative findings in PSP patients. Although chest CT successfully detected most ELCs, 16% of
228
respiratory investigation 51 (2013) 224 –228
the lesions were missed. However, analysis of the PSP size on chest radiography influenced the prediction of ELCs. Combined analysis of chest radiographic and CT findings could improve the sensitivity of ELC detection, and may provide useful information for therapeutic decision making in patients with PSP.
Conflict of interest Takeshi Kawaguchi and the other co-authors have no conflicts of interest to disclose.
references
[1] Willard AF, Paape K. Pneumothorax. In: Shields TW, General thoracic surgery, 5th ed.. Philadelphia: Lippincott Williams and Wilkins; 2000. p. 675–86. [2] Gaunt A, Eartin-Ucar A, Beggs L, et al. Residual apical space following surgery for pneumothorax increases the risk of recurrence. Eur J Cardiothorac Surg 2008;34:169–73. [3] Ayed AK, Chandrasekaran C, Sukumar M. Video-assisted thoracoscopic surgery for primary spontaneous pneumothorax: clinicopathological correlation. Eur J Cardiothorac Surg 2006;29:221–5. [4] Sihoe AD, Yim AP, Lee TW, et al. Can CT scanning be used to select patients with unilateral primary spontaneous pneumothorax for bilateral surgery? Chest 2000;118:380–3. [5] Janssen JP, Schramel FM, Sutedja TG, et al. Videothoracoscopic appearance of first and recurrent pneumothorax. Chest 1995;108:330–4. [6] Naunheim KS, Mack MJ, Hazeirigg SR, et al. Safety and efficacy of video-assisted thoracic surgical techniques for the treatment of spontaneous pneumothorax. J Thorac Cardiovasc Surg 1995;109:1198–204. [7] Czerny M, Salat A, Fleck T, et al. Lung wedge resection improved outcome in stage I primary spontaneous pneumothorax. Ann Thorac Surg 2004;77:1802–5.
[8] Baumann MH, Strange C, Heffner JE, et al. Management of spontaneous pneumothorax. An American College of Chest Physicians Delphi consensus statement. Chest 2001;119:590–602. [9] Henry M, Arnold T, Harvey J. Pleural Diseases Group, Standards of Care Committee, British Thoracic Society. BTS guidelines for the management of spontaneous pneumothorax. Thorax 2003;58(Suppl. 2):ii39–52. [10] Ouanes-Besbes L, Golli M, Knani J, et al. Prediction of recurrent spontaneous pneumothorax: CT scan findings versus management features. Respir Med 2007;101:230–6. [11] Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med 2000;342:868–74. [12] Schramel FM, Postmus PE, Vanderschueren RG. Current aspects of spontaneous pneumothorax. Eur Respir J 1997;10:1372–9. [13] Smit HJ, Wienk MA, Schreurs AJ, et al. Do bullae indicate a predisposition to recurrent pneumothorax? Br J Radiol 2000;73:356–9. [14] Sakurai H. Videothoracoscopic surgical approach for spontaneous pneumothorax: review of the pertinent literature. World J Emerg Surg 2008;3:23. [16] Sawada S, Watanabe Y, Moriyama S. Video-assisted thoracoscopic surgery for primary spontaneous pneumothorax: evaluation of indication and long-term outcome compared with conservative treatment and open thoracotomy. Chest 2005;127:2226–30. [17] Ayed AK, Al-Din HJ. The results of thoracoscopic surgery for primary spontaneous pneumothorax. Chest 2000;118:235–8. [18] Chou SH, Cheng YJ, Kao EL. Is video-assisted thoracic surgery indicated in the first episode primary spontaneous pneumothorax? Interact Cardiovasc Thorac Surg 2003;2:552–4. [19] Margolis M, Gharagozloo F, Tempesta B, et al. Video-assisted thoracic surgical treatment of initial spontaneous pneumothorax in young patients. Ann Thorac Surg 2003;76:1661–4. [20] Barker A, Maratos EC, Edmond L, et al. Recurrence rates of video-assisted thoracoscopic versus open surgery in the prevention of recurrent pneumothoraces: a systematic review of randomized and non-randomized trials. Lancet 2007;370:329–35.
Contents lists available at ScienceDirect
Respiratory Investigation journal homepage: www.elsevier.com/locate/resinv
Original article
Can preoperative imaging studies accurately predict the occurrence of bullae or blebs? Correlation between preoperative radiological and intraoperative findings Takeshi Kawaguchia,b,n, Keiji Kushibea, Motoaki Yasukawaa, Norikazu Kawaia a
Department of Thoracic Surgery, Nara Prefectural Nara Hospital, Japan Department of Thoracic and Cardiovascular Surgery, Nara Medical University School of Medicine, Japan
b
ar t ic l e in f o
abs tra ct
Article history:
Background: Radiological findings of patients with primary spontaneous pneumothorax
Received 28 December 2012
(PSP) undergoing surgery have not been well analyzed. The aim of this study was to
Received in revised form
evaluate the accuracy of imaging studies for predicting the presence of emphysema-like
27 March 2013
changes (ELCs) detectable during surgery.
Accepted 19 April 2013
Methods: Ninety-three PSP patients who underwent surgery from September 2005 to
Available online 5 June 2013
October 2009 were included in the study. We analyzed preoperative chest radiographic
Keywords:
and computed tomographic (CT) findings, and compared the findings with intraoperative
Pneumothorax
detection of ELCs. Chest radiographic findings were analyzed by classifying the PSP size
VATS
into three categories: small, moderate, and complete.
Chest CT
Results: Seventy-six of the 93 patients (82%) had ELCs detected during surgery. The size of
Chest radiography
the PSP on a radiograph was significantly correlated with the presence of ELCs (p¼0.0121). Preoperative CT revealed 64 of the 76 ELCs (sensitivity, 84%; specificity, 100%; accuracy, 87%). Twenty-nine patients without ELCs detected by preoperative CT were analyzed separately. In this group, a larger PSP size also increased the likelihood of ELCs being present (p¼0.0049). Seven patients (8%) experienced a recurrence after surgery. No factor could significantly predict recurrence. Conclusions: Chest CT analysis alone was associated with a false-negative rate of about 15% for ELCs. Combining the analysis of chest radiographic and CT findings could improve sensitivity. & 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.
1.
Introduction
The most common cause of primary spontaneous pneumothorax (PSP) is the rupture of bullae or blebs, which are known as emphysema-like changes (ELCs) [1]. Although the
cause of ELCs is not clear, most patients with PSP have these lesions in their affected lungs, and have them excised if they undergo surgical treatment [2–5]. However, 9–29% of patients undergoing surgery for PSP do not have ELCs, and these patients have a lower postoperative cure rate [2,3,6].
n
Corresponding author at: Department of Thoracic and Cardiovascular Surgery, Nara Medical University School of Medicine, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan. Tel.: +81 744 22 3051; fax: +81 744 24 8040. E-mail addresses: [email protected] (T. Kawaguchi), [email protected] (K. Kushibe), [email protected] (M. Yasukawa), [email protected] (N. Kawai). 2212-5345/$ - see front matter & 2013 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.resinv.2013.04.004
respiratory investigation 51 (2013) 224 –228
Intraoperative findings are important for determining the surgical procedure performed and for predicting the prognosis [7], but the usefulness of preoperative imaging studies in PSP patients is unclear. According to guidelines for the management of PSP [8,9], routine chest computed tomography (CT) is not recommended, because it is not useful for predicting the recurrence of pneumothorax, identifying the cause of a persistent air leak, or deciding the type of surgical intervention. Chest CT is only recommended when aberrant tube placement is suspected, to differentiate a pneumothorax from complex bullous lung disease, or to evaluate pulmonary disorders in cases of secondary pneumothorax. In clinical practice, however, PSP patients often undergo chest CT to screen for ELCs. The aim of this retrospective study was to evaluate the accuracy of the findings of imaging studies taken prior to pneumothorax surgery. We reviewed patients who underwent surgery for PSP, analyzed their preoperative chest radiographic and CT findings, and compared these findings with the intraoperative findings.
2.
Materials and methods
2.1.
Evaluation items
Ninety-three PSP patients who underwent surgery from September 2005 to October 2009 were included in this study. The indications for surgery were prolonged air leakage or repeated pneumothorax, which is basically in line with the recent guidelines [8,9]. Patients with secondary pneumothorax or recurrent PSP after the surgery were excluded from this analysis. PSP patients who did not undergo preoperative chest CT were also excluded. The patients who underwent bilateral surgery were analyzed separately for each side. Preoperative chest radiographic and CT images were retrospectively reviewed for all patients included in the study. The size of the PSP before drainage was categorized according to its appearance on chest radiography: (1) small: the visceral pleura was separated from the chest wall along
225
only part of the pleural space (Fig. 1a); (2) moderate: the visceral pleura was completely separated from the parietal pleura from the base to the apex, but without total lung collapse (Fig. 1b); and (3) complete: the airless lung was separated from the diaphragm (Fig. 1c). We also evaluated ELCs on high-resolution CT scans performed after the reexpansion of the affected lung (Fig. 2). All patients were treated using video-assisted thoracoscopic surgery (VATS) under general anesthesia with singlelung ventilation. Three ports were placed: one in the fourth intercostal space (ICS) at the anterior axillary line, one in the fifth ICS at the posterior axillary line, and one in the seventh ICS at the mid-axillary line. Although most operations were completed with VATS, extension of a port site was necessary for dissection of a pleuropulmonary adhesion or critical location of the targeted area in four patients. When ELCs were identified, these were excised using an endoscopic stapler. If no ELC was identified, the most suspicious areas, such as those with pleuropulmonary adhesions or minute pleural changes, were removed using an endoscopic stapler
Fig. 2 – Emphysema-like change on high-resolution computed tomography after re-expansion of the affected lung.
Fig. 1 – Size of primary spontaneous pneumothorax according to chest radiography. (a) Small, (b) moderate and (c) complete.
226
respiratory investigation 51 (2013) 224 –228
(mostly in the apex of the affected lung). Staple lines were covered with polyglycolic acid felt with fibrin glue in all patients. One patient did not have a suspicious lesion and only underwent placement of the polyglycolic acid felt. In six patients, additional mechanical pleurodesis was performed by scrubbing the parietal pleura. An intercostal drain was placed at the end of the procedure in all patients, and was removed when there was no longer any air leak. After discharge, all patients underwent at least two further chest radiographies during the follow-up care. Recurrence was defined as a further pneumothorax occurring after the end of treatment.
2.2.
3.
Results
3.1.
Patient characteristics
Patient characteristics are shown in Table 1. Approximately 50% of the patients (47%, 44/93) were classified as having a complete collapse. ELCs were detected in 64 patients (68%, 64/93) by preoperative chest CT, and in 76 patients during surgery (82%, 76/93). The postoperative pneumothorax recurrence rate was 8% (7/93).
3.2. Comparison of preoperative imaging studies and intraoperative findings
Statistical analysis
Univariate analyses were performed using the Mann–Whitney U test and χ2 test. Statistical significance was set at po0.05. Table 1 – Patient characteristics. Characteristics
Number
Age (years) Mean7standard deviation
32716
Sex Male Female
74 19
Size of PSP by chest radiography Small Moderate Complete
24 25 44
Presence of ELC by chest CT Yes No
64 29
Surgical procedure Wedge resection with coverage Wedge resection with coverage and pleurodesis Coverage and pleurodesis without resection
86 6 1
Intraoperative detection of ELC Yes No
76 17
Recurrence of PSP Yes No
7 86
Correlations between the size of the PSP in the chest radiographic and intraoperative findings are shown in Table 2. The size of the PSP was significantly correlated with the presence of ELCs (p ¼0.0121). Correlations between preoperative CT and intraoperative findings are shown in Table 3. Although 64 of the 76 ELCs were detected by preoperative chest CT, 12 were missed (sensitivity, 84%; specificity, 100%; accuracy, 87%). Subsequently, the 29 patients without ELCs on CT were analyzed separately. In this group, a larger PSP size on chest radiography was also significantly correlated with the presence of ELCs (p¼ 0.0049, Table 4).
3.3. Patients with subsequent recurrence of PSP after surgery Seven patients experienced a recurrent pneumothorax after surgery, and their details are shown in Table 5. Five of the seven patients had targeted ELCs during surgery. The χ2 test showed that no factor could significantly predict recurrence
CT: computed tomography; PSP: primary spontaneous pneumothorax; ELC: emphysema-like change.
Table 3 – Correlations between preoperative CT and intraoperative findings in all patients (n ¼93). Intraoperative detection of ELC Yes (n ¼ 76) ELC detection by chest CT Yes (n ¼64) 64 No (n ¼ 29) 12
No (n ¼17)
0 17
CT: computed tomography; ELC: emphysema-like change.
Table 2 – Correlations between the size of the PSP and intraoperative findings. p Value
Intraoperative detection of ELC
Size of PSP according to chest radiography Small (n ¼ 24) Moderate (n ¼ 25) Complete (n ¼44)
Yes (n ¼76)
No (n ¼17)
15 21 40
9 4 4
PSP: primary spontaneous pneumothorax; ELC: emphysema-like change.
0.0121
227
respiratory investigation 51 (2013) 224 –228
Table 4 – Correlations between the size of the PSP and intraoperative findings in patients without ELCs by CT (n ¼ 29). p Value
Intraoperative detection of ELC
Size of PSP according to chest X-ray Small (n ¼10) Moderate (n ¼6) Complete (n ¼13)
Yes (n ¼ 12)
No (n ¼17)
1 2 9
9 4 4
0.0049
PSP: primary spontaneous pneumothorax; ELC: emphysema-like change; CT: computed tomography.
Table 5 – Patients with subsequent recurrence of PSP after surgery.
Case Case Case Case Case Case Case
1 2 3 4 5 6 7
Radiographic finding
CT finding
Intraoperative finding
Complete Moderate Moderate Moderate Moderate Complete Complete
ELC ELC ELC ELC ELC ELC ELC
ELC ELC ELC ELC ELC ELC ELC
(−) (+) (+) (−) (−) (−) (+)
(+) (+) (+) (−) (−) (+) (+)
PSP: primary spontaneous pneumothorax; CT: computed tomography; ELC: emphysema-like change.
(size of PSP: p ¼0.8986; CT finding: p ¼0.1231; intraoperative findings: 0.4638).
4.
Discussion
A diagnosis of PSP is usually made on the basis of the clinical history and is confirmed by chest radiography. Although every patient with PSP underwent chest radiography, the radiological findings of PSP patients have not been well analyzed. It has been reported that chest CT findings have no prognostic value [10–13]. Radiological examination findings therefore do not usually influence treatment choices in patients with PSP [8,9]. However, intraoperative findings have been reported to correlate with postoperative morbidity and recurrence, and are known to predict outcomes after PSP surgery [2,3,6,7,14]. Most patients with PSP undergo chest CT to screen for ELCs. In the present analysis, intraoperative identification of ELCs was compared with preoperative identification of ELCs by using chest radiographic and chest CT findings. First, the size of the PSP evaluated by chest radiography was significantly correlated with the presence of ELCs. Second, not every ELC was detected by chest CT. Although most ELCs were detected by chest CT in this study, 12 detectable lesions (16%, 12/76) were missed. The accuracy rate may be improved by combining chest CT with chest radiographic analysis. In patients without ELCs detected on chest CT, greater lung collapse on radiography increased the likelihood of ELCs being present. Possible reasons for the false-negative chest CT findings may be related to the size and location of the lesions, or to the collapse of lesions. ELCs are generally predominant in the lung apex [1]. Evaluation of a small low-attenuation area at
the apex is sometimes difficult due to the variety of lung parenchymal and pleural changes seen in this region [3]. False-negative results are inevitable when only chest CT findings are evaluated. Our analysis did not identify any factor predictive of recurrent PSP after surgery. Intraoperative detection of ELCs also had no predictive value for recurrence. It may be that our sample size was too small for such a rare event. According to recent guidelines [9,10], surgery is indicated in patients with repeated ipsilateral PSP, first contralateral PSP, bilateral PSP, PSP with persistent air leak, hemothorax, and an at-risk profession. With advances in video thoracoscopic equipment, most surgeries to treat PSP are performed via VATS, which is less invasive and has outcomes similar to open thoracotomy [16,17]. Based on its minimal invasiveness and cosmetic advantage, some reports have recommended surgery for patients experiencing their first episode of PSP [18,19]. However, the recurrence rate associated with the VATS approach is higher than that of the open approach [20]. Based on the guideline recommendations, patients and clinicians make medical decisions considering the potential risk of recurrence, the invasiveness of the treatment, and the treatment outcome, among other factors. ELCs are the main targets of surgery to correct PSP. Furthermore, patients with ELCs who undergo surgery for PSP also have a good prognosis [2,3,6]. Therefore, precise prediction of ELCs as surgical targets influences clinical decision-making.
5.
Conclusions
In this study, preoperative chest radiographic and CT findings were compared with intraoperative findings in PSP patients. Although chest CT successfully detected most ELCs, 16% of
228
respiratory investigation 51 (2013) 224 –228
the lesions were missed. However, analysis of the PSP size on chest radiography influenced the prediction of ELCs. Combined analysis of chest radiographic and CT findings could improve the sensitivity of ELC detection, and may provide useful information for therapeutic decision making in patients with PSP.
Conflict of interest Takeshi Kawaguchi and the other co-authors have no conflicts of interest to disclose.
references
[1] Willard AF, Paape K. Pneumothorax. In: Shields TW, General thoracic surgery, 5th ed.. Philadelphia: Lippincott Williams and Wilkins; 2000. p. 675–86. [2] Gaunt A, Eartin-Ucar A, Beggs L, et al. Residual apical space following surgery for pneumothorax increases the risk of recurrence. Eur J Cardiothorac Surg 2008;34:169–73. [3] Ayed AK, Chandrasekaran C, Sukumar M. Video-assisted thoracoscopic surgery for primary spontaneous pneumothorax: clinicopathological correlation. Eur J Cardiothorac Surg 2006;29:221–5. [4] Sihoe AD, Yim AP, Lee TW, et al. Can CT scanning be used to select patients with unilateral primary spontaneous pneumothorax for bilateral surgery? Chest 2000;118:380–3. [5] Janssen JP, Schramel FM, Sutedja TG, et al. Videothoracoscopic appearance of first and recurrent pneumothorax. Chest 1995;108:330–4. [6] Naunheim KS, Mack MJ, Hazeirigg SR, et al. Safety and efficacy of video-assisted thoracic surgical techniques for the treatment of spontaneous pneumothorax. J Thorac Cardiovasc Surg 1995;109:1198–204. [7] Czerny M, Salat A, Fleck T, et al. Lung wedge resection improved outcome in stage I primary spontaneous pneumothorax. Ann Thorac Surg 2004;77:1802–5.
[8] Baumann MH, Strange C, Heffner JE, et al. Management of spontaneous pneumothorax. An American College of Chest Physicians Delphi consensus statement. Chest 2001;119:590–602. [9] Henry M, Arnold T, Harvey J. Pleural Diseases Group, Standards of Care Committee, British Thoracic Society. BTS guidelines for the management of spontaneous pneumothorax. Thorax 2003;58(Suppl. 2):ii39–52. [10] Ouanes-Besbes L, Golli M, Knani J, et al. Prediction of recurrent spontaneous pneumothorax: CT scan findings versus management features. Respir Med 2007;101:230–6. [11] Sahn SA, Heffner JE. Spontaneous pneumothorax. N Engl J Med 2000;342:868–74. [12] Schramel FM, Postmus PE, Vanderschueren RG. Current aspects of spontaneous pneumothorax. Eur Respir J 1997;10:1372–9. [13] Smit HJ, Wienk MA, Schreurs AJ, et al. Do bullae indicate a predisposition to recurrent pneumothorax? Br J Radiol 2000;73:356–9. [14] Sakurai H. Videothoracoscopic surgical approach for spontaneous pneumothorax: review of the pertinent literature. World J Emerg Surg 2008;3:23. [16] Sawada S, Watanabe Y, Moriyama S. Video-assisted thoracoscopic surgery for primary spontaneous pneumothorax: evaluation of indication and long-term outcome compared with conservative treatment and open thoracotomy. Chest 2005;127:2226–30. [17] Ayed AK, Al-Din HJ. The results of thoracoscopic surgery for primary spontaneous pneumothorax. Chest 2000;118:235–8. [18] Chou SH, Cheng YJ, Kao EL. Is video-assisted thoracic surgery indicated in the first episode primary spontaneous pneumothorax? Interact Cardiovasc Thorac Surg 2003;2:552–4. [19] Margolis M, Gharagozloo F, Tempesta B, et al. Video-assisted thoracic surgical treatment of initial spontaneous pneumothorax in young patients. Ann Thorac Surg 2003;76:1661–4. [20] Barker A, Maratos EC, Edmond L, et al. Recurrence rates of video-assisted thoracoscopic versus open surgery in the prevention of recurrent pneumothoraces: a systematic review of randomized and non-randomized trials. Lancet 2007;370:329–35.