Pneumothorax is a thoracic disorder manifested as abnormal collection of air in the pleural space [
Risk factors for PSP include tall-and-thin body shape, maleness, and smoking [
This study analyzed the differences in demographic and clinical features between patients with PSP and SSP in a Japanese population. Since early treatment and prompt clinical assessment are the cornerstones of successful clinical outcome, we hypothesized that “emergency transportation”, that is, transport of a patient with SP by ambulance to the emergency department (ED), might be a critical factor in the management of patients with SSP. To this end, factors associated with in-hospital mortality were identified by multivariate logistic regression analysis. Resolution of pneumothorax, treatment protocol, and underlying diseases were also analyzed in case of patients who died during hospitalization.
This retrospective study included patients who presented with the diagnosis of “pneumothorax” at the Tsuchiura Kyodo General Hospital, Ibaraki, Japan, between January 2004 and December 2014. Patient records were retrieved by the electronic clinical data analysis and retrieval system according to the International Classification of Diseases, Ninth Revision, codes 512.0 (spontaneous pneumothorax). Patients with traumatic, iatrogenic, or wrong diagnoses as well as those below the age of 10 years were excluded. Patients who were initially transferred from another hospital for management were included but not considered under the category of “emergency transportation” (defined later). In this study, SPs that did not result in hospitalization were not included. The number of pneumothoraxes was determined, and multiple entries were considered to include metachronous pneumothoraxes. The institutional review board of the Tsuchiura Kyodo General Hospital approved this study (Approval Number: 533) and written oral informed consent was received from majority of the participants while the rest of them provided only verbal consent.
Data including demographic information, type of pneumothorax, laterality, smoking status, emergency transportation, surgical intervention, in-hospital mortality, and length of stay (LOS) were collected. X-ray radiographs of all included patients were retrieved. Underlying pulmonary diseases were recorded for all patients with SSP.
Primary SP was defined as SP in a person without an underlying lung disease, whereas SSP was defined as SP with an underlying lung disease [
Modified ECOG performance status for this study.
Grade | Content |
---|---|
0 | Fully active without restriction |
1 | Restricted in physically strenuous activities, but ambulatory and able to carry out work of a light or sedentary nature |
2 | Ambulatory and capable of all self-care, but unable to carry out any work activities; up and about for more than 50% of waking hours |
3 | Capable of only limited self-care; confined to bed or a chair for more than 50% of waking hours |
4 | Completely disabled; cannot perform any self-care; completely confined to bed or a chair |
ECOG, Eastern Cooperative Oncology Group.
Treatment modalities included oxygen inhalation (OI), chest drainage with a chest tube (16–24 Fr), and video-assisted thoracoscopic surgery (VATS) with wedge resection, which was performed in case of recurrence or failure of treatment by OI and simple chest tube insertion. Mild SP was treated by observation only or by continuous chest drainage for a few days. Recurrence rate was defined by the percentage of patients who exhibited SP during the follow-up period. Patients who received nonsurgical treatment were followed-up for a few weeks, while those who underwent surgery were followed up for 2-3 months
Baseline characteristics were described using descriptive statistics. Patient characteristics and treatment outcomes were compared by the chi-square test, Fisher’s exact test, or
Of the 751 patients (male, 649; 86.4%) included in the present study, 142 (18.9%) presented with metachronous SP. While 485 (64.5%) patients exhibited PSP, 266 (35.4%) presented with SSP. There were no differences in sex between the PSP and SSP groups (proportion of male patients: PSP versus SSP, 86.6% versus 86.1%;
The total number of pneumothoraxes among the included patients was 938, with 13.8% of pneumothoraxes being observed in women. The mean age at the time of presentation of pneumothorax was 43 ± 13 years. While 48% of pneumothoraxes were left lateral, only 1.2% were bilateral. A significant proportion of patients exhibiting pneumothoraxes were smokers (65.7%), while 50.8% received surgical treatment, and 8.7% received emergency transportation. In-hospital mortality was 1.7%, and the average LOS was 11 ± 13 days (Table
Demographic distribution and clinical features of spontaneous pneumothorax.
SP | PSP | SSP |
|
|
---|---|---|---|---|
Number of pneumothoraxes | 938 | 611 (65.1) | 327 (34.9) | |
Patients | 751 | 485 (64.6) | 266 (35.4) | |
Age at the time of pneumothorax (Mean ± SD) | 43 ± 13 | 27 ± 12 | 70 ± 14 | < |
Sex-wise distribution of pneumothoraxes | ||||
Men | 809 (86.2) | 533 (65.9) | 276 (34.1) |
|
Women | 129 (13.8) | 78 (60.5) | 51 (39.5) | |
Laterality | ||||
Left | 450 (48.0) | 314 (51.4) | 136 (41.6) |
|
Right | 476 (50.7) | 288 (47.2) | 188 (57.5) | |
Bilateral | 11 (1.2) | 8 (1.3) | 3 (0.9) | |
Unknown | 1 (0.1) | 1 (0.1) | 0 (0.0) | |
Smoking status | ||||
Smoker | 593 (63.2) | 402 (67.8) | 191 (32.2) |
|
Never | 336 (35.7) | 203 (60.4) | 133 (39.6) | |
Unknown | 9 (0.1) | 6 (66.7) | 3 (33.3) | |
Emergency transportation (%) | 82 (8.7) | 15 (2.4) | 67 (20.5) | < |
Surgical intervention (%) | 477 (50.8) | 374 (61.2) | 103 (31.5) | < |
LOS days (median ± SD) | 11 ± 13 (8) | 9 ± 5 (8) | 16 ± 20 (11) | < |
In-hospital mortality | 16 (1.71) | 1 (0.16) | 15 (4.59) | < |
Data are presented as
With regard to treatment modality, 459 (48.9%) patients received chest drainage; 54 (5.8%) patients received surgery; 423 (45.1%) patients received surgery after chest drainage; and 2 patients (0.2%) only required observation (Table
Therapeutic methods employed for management of spontaneous pneumothorax.
Chest drainage (with/without pleurodesis) | 459 |
Surgery (with/without pleurodesis) | 54 |
Chest drainage followed by surgery (with/without pleurodesis) | 423 |
Observation only | 2 |
Recurrence rates of pneumothorax in the PSP and SSP groups.
Cases | (%) | |
---|---|---|
Nonsurgical treatment (drainage with/without pleurodesis or observation only) | ||
PSP | 58 | 24.5 |
SSP | 39 | 17.4 |
Surgery (with/without pleurodesis) | ||
PSP | 10 | 2.7 |
SSP | 2 | 1.9 |
PSP, primary spontaneous pneumothorax; SSP, secondary spontaneous pneumothorax.
In the present study, 65.1% of the pneumothoraxes were PSP. The mean age at the time of presentation of pneumothorax in the PSP group was significantly lower compared to that in the SSP group (27 ± 12 years versus 70 ± 14 years;
The underlying pulmonary diseases in 266 patients of the SSP group are summarized in Table
Underlying pulmonary diseases in patients with secondary spontaneous pneumothorax (
Disease |
|
---|---|
Pulmonary emphysema | 195 (73.3) |
Interstitial pneumonitis or pulmonary fibrosis | 21 (7.9) |
Lung cancer | 20 (7.5) |
Infectious disease (pneumonia, pneumomycosis, etc.) | 12 (4.5) |
Catamenial pneumothorax | 8 (3.0) |
Nontuberculous mycobacterial infection | 7 (2.6) |
Birt-Hogg-Dubé syndrome | 4 (1.5) |
Obsolete pulmonary tuberculosis | 3 (1.2) |
Others | 9 (3.4) |
In the SSP group, multivariate analysis of sex, laterality, smoking status, and emergency transportation revealed only emergency transportation (OR, 16.47; 95% CI, 4.85–55.20;
Multivariate analysis of factors associated with in-hospital mortality in patients with secondary spontaneous pneumothorax.
OR | 95% CI |
|
|
---|---|---|---|
Sex | 3.9 | 0.94–16.25 | 0.06 |
Laterality | 0.59 | 0.19–1.78 | 0.35 |
Smoking status | 1.17 | 0.30–4.49 | 0.82 |
Emergency transportation | 16.37 | 4.85–55.20 | <0.001 |
OR, odds ratio; CI, confidence interval.
Tables
Demographic and clinical details of patients with spontaneous pneumothorax according to requirement for emergency transportation.
Patients | Age (years) | Sex | Laterality | Emergency transportation | Smoking status |
PS before pneumothorax | PSP/SSP | Existing respiratory diseases |
---|---|---|---|---|---|---|---|---|
1 | 62 | M | R | Yes | Yes | 4 | SSP | Lung cancer |
2 | 68 | M | L | Yes | Yes | 2 | SSP | Pulmonary emphysema, pneumonia |
3 | 72 | M | R | No | Yes | 1 | SSP | Pulmonary emphysema |
4 | 72 | M | R | Yes | Yes | 2 | SSP | Pulmonary emphysema |
5 | 74 | M | R | Yes | Unknown | 3 | SSP | Pneumonia |
6 | 76 | M | R | Yes | Yes | 0 | SSP | Lung cancer, pneumonia |
7 | 77 | M | L | Yes | Yes | 1 | SSP | Pulmonary emphysema |
8 | 78 | M | L | No | Never | 3 | SSP | Pulmonary emphysema |
9 | 79 | F | R | No | Yes | 2 | SSP | Pneumonia, pyothorax |
10 | 80 | M | L | Yes | Yes | 3 | SSP | Pulmonary emphysema, pneumomycosis |
11 | 85 | F | L | Yes | Never | 4 | SSP | Interstitial pneumonitis |
12 | 86 | M | R | Yes | Yes | 3 | SSP | Interstitial pneumonitis |
13 | 87 | F | R | Yes | Never | 4 | SSP | Lung cancer |
14 | 87 | M | L | Yes | Yes | 3 | SSP | Pulmonary emphysema, pneumonia |
15 | 94 | F | R | No | Never | 3 | SSP | Obsolete tuberculosis |
16 | 96 | M | R | Yes | Yes | 3 | PSP | — |
L, left; R, right; PS, performance status according to the Eastern Cooperative Oncology Group; PSP, primary spontaneous pneumothorax; SSP, secondary spontaneous pneumothorax.
Therapy, LOS, progress of pneumothorax, and cause of death in patients with spontaneous pneumothorax.
Patients | Therapy | LOS (days) | Progress of pneumothorax | Direct cause of death |
---|---|---|---|---|
1 | CD + pleurodesis | 14 | NC | Lung cancer |
2 | CD + pleurodesis | 16 | Cured | Pneumonia |
3 | Surgery | 13 | NC | Pyothorax, postoperative respiratory failure |
4 | Surgery | 274 | Cured | Post-operative respiratory failure |
5 | CD | 5 | NC | Pneumonia |
6 | CD | 56 | Cure | Lung cancer |
7 | CD | 8 | Cure | Exacerbation of chronic respiratory failure |
8 | CD + pleurodesis | 15 | Cure | Pyothorax |
9 | CD + pleurodesis | 23 | NC | Pneumothorax followed by respiratory failure |
10 | CD + pleurodesis | 23 | NC | Sepsis followed by multiple organ failure |
11 | Observation only | 30 | NC | Pneumothorax followed by respiratory failure |
12 | CD | 19 | NC | Intestinal pneumonitis |
13 | Observation only | 66 | NC | Pneumothorax followed by general prostration |
14 | CD | 8 | NC | Cardiac disease (details unknown) |
15 | CD | 32 | NC | Pyothorax, respiratory failure |
16 | CD + pleurodesis | 59 | Cure | Pneumothorax followed by multiple organ failure |
CD, chest drainage; LOS, length of stay; NC, no change.
This study reports that emergency transportation is an independent factor associated with in-hospital mortality in SSP. Our results further suggest that PSP and SSP have several significantly different clinical and demographic features. Old age, right laterality, and nonsmoking status were more prevalent in the SSP group than in the PSP group, while surgical interventions and left laterality were more frequent in latter. There were more men than women in both groups. The proportion of women with SSP was greater compared to that with PSP, although the difference did not reach statistical significance.
The most frequent underlying pulmonary disease in SSP was pulmonary emphysema, which corresponds with previous reports [
There were significant differences in emergency transportation, surgical intervention, LOS, and in-hospital mortality between the PSP and SSP groups in the present study. The requirement for emergency transportation, LOS, and in-hospital mortality in the SSP group was much greater compared to those in the PSP group. However, the SSP group was not homogeneous in composition. It comprised an older population than the PSP group, and the clinical manifestations of SSP varied among the patients, depending on the underlying pulmonary disease. Therefore, the SSP group tended to involve more instances of emergency transportation and longer hospital stay than the PSP group. However, in multivariate analysis involving sex, laterality, smoking status, and emergency transportation as variables, only emergency transportation was found to be independent factors associated with in-hospital mortality.
The frequency of surgical interventions in the SSP group was considerably lower compared to that in the PSP group, which might seem contradictory to the results of recent studies that established the efficacy of surgical intervention for SSP and advocated in favor of video-assisted thoracic surgery [
Among patients who received emergency transportation, only 3 presented with light pneumothorax and, therefore, did not receive invasive treatment. All other patients (79 cases of SP) received chest drainage in the ED as soon as possible after diagnosis of pneumothorax by X-ray radiography. Since only patients with PS 4 have to rely on emergency transportation, we performed subgroup analysis of the data after excluding patients exhibiting PS 4. Despite this exclusion, emergency transportation remained an independent factor for in-hospital mortality. This suggests that, at least among Japanese patients, clinicians should more carefully treat patients with SSP who are being transported in emergency. It may be noted that, among the 16 patients who died during hospitalization, 12 (75.0%) had received emergency transportation, 15 (93.8%) had presented with SSP, and 10 (62.5%) had exhibited PS of 3 or 4.
There are some limitations to this study. The study was of retrospective, observational, and single-institution design. Although there were no major changes in therapeutic strategies for SP during the study period, minor changes, such as new antibiotics or surgical devices, might have been implemented. Therefore, small therapeutic changes could have existed between the early and late periods of the study. Since emergency transportation systems vary among countries, it is necessary to consider country-specific factors while generalizing our results. All of the patients who died during hospitalization were above 60 years of age and had underlying diseases, which precluded confounding control for age and/or comorbidity. Further studies are required to analyze the role of these potential confounders. Because it was not possible to evaluate the PS in all 938 instances of pneumothorax, we could not include PS as a confounder in multivariate analysis. However, 37.5% of patients who died during hospitalization exhibited PS ≤ 2, and our results revealed a significantly higher rate of in-hospital mortality among patients with PS = 4 than among patients with PS < 4, which suggests that size and severity of pneumothorax, age, performance status, body mass index, and SP-associated comorbidities should to be analyzed in future studies to fully establish “emergency transportation” as an independent risk factor. We stress that our results should be interpreted within these limitations. Nevertheless, the present results are noteworthy for highlighting the possible role of emergency transportation in in-hospital mortality among patients with SP and presenting the associated clinical features of SP in the Japanese population. This study is expected to stimulate further research on identifying factors that might allow better clinical management of such high-risk patients.
Sex, age, laterality, and smoking status vary significantly between patients with PSP and SSP in Japan. Our results also underscore the significance of emergency transportation for patients with SSP and suggest that patients with SSP receiving emergency transportation should receive careful attention irrespective of their PS. To the best of our knowledge, this is the first report on the significance of emergency transportation for patients with PSP and SSP in the Japanese population.
The authors declare that there is no conflict of interests regarding the publication of this paper.
No funding was received for this research.
Editorial support, in the form of medical writing based on authors’ detailed directions, collating author comments, copyediting, fact checking, and referencing, was provided by Cactus Communications.