The size of spontaneous pneumothorax is a predictor of unsuccessful catheter drainage

ABSTRACT Small-bore thoracic catheter drainage is recommended for a first large or symptomatic episode of primary spontaneous pneumothorax (PSP). However, one-third of these patients require

a second procedure because of treatment failure. We investigated the factors associated with unsuccessful pigtail catheter drainage in the management of PSP. In this retrospective study,

using a prospectively collected database, we enrolled 253 consecutive patients with PSP who underwent pigtail catheter drainage as initial treatment, from December 2006 to June 2011. The

chest radiograph was reviewed in each case and pneumothorax size was estimated according to Light’s index. Other demographic factors and laboratory data were collected via chart review.

Pigtail catheter drainage was successful in 71.9% (182/253) of cases. Treatment failure rates were 42.9%, 25.9%, and 15.5% in patients with pneumothorax sizes of >62.6%, 38–62.6%, and

<38%, respectively (tertiles). An alternative cut-off point of 92.5% lung collapse was defined using a classification and regression tree method. According to the multivariate analysis, a

large-size pneumothorax (_p_ = 0.009) was the only significant predictor of initial pigtail catheter drainage treatment failure in patients with PSP. Early surgical treatment could be

considered for those patients with a large-sized pneumothorax. SIMILAR CONTENT BEING VIEWED BY OTHERS TRENDS IN RECURRENCE OF PRIMARY SPONTANEOUS PNEUMOTHORAX IN YOUNG POPULATION AFTER

TREATMENT FOR FIRST EPISODE BASED ON A NATIONWIDE POPULATION DATA Article Open access 18 August 2023 RECOMMENDATION FOR MANAGEMENT OF PATIENTS WITH THEIR FIRST EPISODE OF PRIMARY SPONTANEOUS

PNEUMOTHORAX, USING VIDEO-ASSISTED THORACOSCOPIC SURGERY OR CONSERVATIVE TREATMENT Article Open access 25 May 2021 THE UNNECESSARY WORKUPS AND ADMISSIONS OF ADOLESCENTS AND YOUNG ADULTS

WITH SPONTANEOUS PNEUMOMEDIASTINUM Article Open access 24 February 2024 INTRODUCTION Primary spontaneous pneumothorax (PSP) is defined as the trapping of air in the pleural cavity of

patients without underlying lung disease or thoracic trauma. PSP usually affects young and tall male patients, often adolescents with a slim build. The global incidence is 7.4–18/1,000,000

men per year and 1.2–6/1,000,000 women per year1, 2. The optimal treatment for patients presenting with a first episode of PSP is controversial and existing guidelines vary3,4,5. The British

Thoracic Society (BTS) 2010 pleural disease guidelines recommended needle aspiration (14–16 G) or small-bore (<14 French, 4.7-mm diameter) thoracic catheter drainage as the first-line

treatment for patients with a large PSP3. However, the results of simple aspiration are not satisfactory for a large portion of patients. First, the success rate of needle aspiration varies

widely in the literature, ranging from 38%–85%6,7,8,9,10,11,12,13,14,15; second, almost one-third of patients need an additional invasive procedure6. Therefore, several modified strategies,

including thoracostomy with chest tube or pigtail catheter, chemical pleurodesis with sclerosing agents, or video-assisted thoracic surgery are generally required16, 17. The issue of initial

treatment failure in PSP is important. An appropriately selected treatment strategy leads to a better outcome and less waste of medical resources. In some patients with a high risk of

treatment failure, physicians may choose a more efficient management approach than simple aspiration. Since 1985, several studies focused on this issue, and reported several factors

associated with treatment failure with simple aspiration. These factors included age >50 y, pre-existing lung disease, a large volume of aspiration, and pneumothorax size6, 10, 12, 18,

19. Harvey _et al._ reported a significant difference in the amount of air aspirated between successfully treated patients and those who showed treatment failure6. In a retrospective study

with 91 cases, Chan _et al._ reported that treatment was more likely to fail in patients with a large pneumothorax (>40%)10. However, these studies were limited by their retrospective

nature, small study populations (<100 cases), and heterogeneous patient populations. Furthermore, there have been no previous studies discussing the factors affecting initial treatment

failure after catheter drainage. The aim of our study was to investigate the risk factors associated with treatment failure of PSP treated with a small-bore (8-French) pigtail catheter for

thoracic drainage as the initial treatment based on a prospectively collected, single-center database in a large homogenous patient population. RESULTS CHARACTERISTICS OF PATIENTS From 2006

to 2011, a total of 253 patients were enrolled into the study and underwent trans-thoracic pigtail catheter insertion and drainage. Overall, 182 patients were successfully treated by this

method (71.9%; success group) and 71 patients were considered treatment failures (28.1%; failure group). The failure group included 60 cases with persistent air-leaks at 72 hours after the

procedure and 11 cases who showed an enlarging pneumothorax on serial chest radiographs after the pigtail catheter was removed. In these 11 cases, the catheters were all removed once there

were no ongoing air-leaks. Table 1 demonstrates the clinical features of the two groups. We carefully recorded every patient’s clinical data with a thorough chart review. Both groups were

composed of younger adults (mean age: 22.5 ± 5.5 y) with a slim body shape (body mass index [BMI] = 19.3 ± 2.3 kg/m2). A smoking history did not affect the outcome of treatment (_p_ = 

0.641). In our study, more patients had a pneumothorax affecting the left side (147/253, 58.10%), but there was no significant difference in treatment outcome based on the side of the

pneumothorax (_p_ = 0.943). There were no significant differences in hemoglobin, white blood cell (WBC) count, and renal or hepatic function between the successfully treated patients and

those with treatment failure. SIZE OF PNEUMOTHORAX AND TREATMENT OUTCOMES In our study, the only factor that had a significant impact on the treatment outcome was the size of the

pneumothorax. The treatment failure group had a significantly larger-sized lung collapse than the successfully treated group (60 ± 0.23% vs. 51 ± 0.21%, _p_ = 0.004). Table 2 shows the

relationship between pneumothorax size and treatment outcome. We split the 253 patients into tertiles according to their initial pneumothorax size, as determined by chest radiography. Based

on these measurements, the size of the pneumothorax was classified into three categories based on the severity of lung collapse: massive (>62.6%), moderate (38–62.6%), and mild (<38%)

collapse. In patients with a mild collapse, the treatment success rate was 84.52%; while in patients with a massive collapse, the success rate was 57.15%. Further analysis revealed a trend

showing that, the larger the size of the lung collapse, the more likely it was that treatment would fail. We also created an alternative statistical model using the classification and

regression tree (CART) method. In this model, all patients were divided into two groups according to the cut-off point of 92.5% lung collapse. Table 3 shows the multivariate logistic

regression analysis of the risk factors. Massive collapse (>92.5%) was associated with a higher risk of treatment failure than in other cases, with an OR of 4.23 (95% confidence interval 

= 1.43–12.47, _p_ = 0.0091). Other factors, including age, BMI, and smoking status were not associated risk factors. There were no major complications associated with the pigtail catheter

insertion, such as hemothorax, lung penetrating injury caused by the pigtail catheter, or other solid organ injury. LONG-TERM FOLLOW-UP OUTCOMES The long-term follow-up outcomes of the 253

patients were recorded after chart review and phone interview, with a mean follow-up period of 90.9 ± 14.6 (range: 60–114) months. Figure 1 summarizes the results of the long-term follow-up.

The recurrence rate in the success group was 29.1% (53/182 cases). The 71 patients with initial treatment failure underwent salvage video-assisted thoracoscopic surgery (VATS, described in

the Methods section). The recurrence rate of the patients who received salvage VATS was 12.7% (9/71 cases). Among the patients who underwent salvage VATS, pathological examination revealed

that 85.9% (61/71) had bullae, and 12.7% (9/71) had blebs. One case showed emphysematous changes without formation of bullae or blebs. DISCUSSION Pneumothorax remains a challenging disease

with a lack of optimal treatment guidelines, especially for those patients experiencing a first episode or “large”-sized pneumothorax. The currently available guidelines, including those set

out by the British Thoracic Society (BTS), the American College of Chest Physicians (ACCP), and the Belgian Society of Pulmonology (BSP), all differ in their recommendations for treatment

of a large-sized PSP3,4,5. The initial treatment strategies include conservative treatment, simple aspiration, and intercostal pleural drainage with a small-bore pigtail catheter or

traditional large-bore catheter3,4,5, 16, 17. Traditional conservative treatment includes bed rest, supplemental high flow oxygen, and analgesics. Both bed rest and high-flow oxygen

supplementation improve trans-thoracic air reabsorption20, 21. When conservative treatment fails, or is not suitable, invasive treatment, such as the placement of trans-thoracic drains

should be considered. Both the BTS and ACCP guidelines recommend simple aspiration or small-bore trans-thoracic drainage as the initial treatment for PSP3, 4. The role of trans-thoracic

drainage in PSP is to remove excess intrapleural air and promote apposition of the visceral and parietal pleura, initiating the process of healing of the lung defect. A retrospective study

by Chan _et al._ used a homogenous population of 91 PSP patients treated with simple aspiration, and revealed that treatment failure was associated with a pneumothorax with a size ≥40%10.

However, that study had several limitations, including its retrospective design, the lack of a universal protocol for estimating pneumothorax size, and a low rate of successful treatment

(50.5%). Our study is the largest study of patients undergoing initial PSP treatment to date, and is based on a prospectively collected, single-center database with a homogenous patient

population. We employed the Light index, which is an easily implemented method, for the estimation of pneumothorax size. Our study observed that a large-sized pneumothorax is the only factor

associated with treatment failure. Patients with a larger pneumothorax are more likely to experience treatment failure. We recommend trans-thoracic drainage with a small-sized

trans-thoracic pigtail catheter instead of simple aspiration in PSP patients with a small pneumothorax. We routinely connect the pigtail catheter to a water-sealed bottle, which acts as a

single-bottle underwater seal chest drainage system, thereby providing continuous trans-thoracic air drainage. The effect of drainage can be augmented with low-pressure negative suction

(usually −10 to −20 cmH2O)22. Patient safety is always a concern, and pigtail catheter insertion is easy to perform and less invasive than other procedures23. Additionally, unlike simple

aspiration, insertion of the pigtail catheter does not require repeat procedures. The complications of pigtail catheter insertion are few, especially in young and medically uncomplicated

populations24, 25. With continuous monitoring of the trans-thoracic space, we can monitor when air-leaking resolves and can respond immediately to any emergency conditions, such as a delayed

hemothorax. We acknowledge that there are limitations to this study. First, it is difficult to measure the pneumothorax volume accurately from chest radiographs, which are two-dimensional

images, because the pleural cavity is a three-dimensional structure. However, chest radiography is the most common and accessible method to diagnose PSP in most institutes. Therefore, we

decided to use chest radiography, rather than chest computed tomography, to estimate the size of the pneumothorax. On the other hand, this means that our findings might be helpful in

settings where computed tomography is not readily available. Second, because our institute lacked the appropriate equipment, we did not record the volume of the air-leaks in this study. A

large volume of aspirated air may be related to the size of the pneumothorax, and the BTS guidelines use 2.5 L as the limit for simple aspiration because of the likely presence of persistent

air leak. Finally, our study is a retrospective-based analysis similar to other existing literature. Further prospective randomized clinical trials with larger study populations are

necessary. We reported our experience with a large cohort of 253 PSP patients who underwent pigtail catheter drainage, and concluded that the size of the pneumothorax is the only prognostic

factor associated with treatment outcome in PSP. Trans-thoracic pigtail catheter drainage has several advantages over simple aspiration. In addition, with the advances in thoracoscopic

surgery over the past decade, VATS has become a safe intervention for PSP as the first-line surgical intervention or salvage strategy26,27,28. Early thoracoscopic procedures can be

considered as a first-line treatment for patients with a large pneumothorax. METHODS STUDY DESIGN AND PATIENTS This study was based on the retrospective analysis of a prospectively collected

database. From December 2006 through June 2011, a total of 253 patients with a diagnosis of primary pneumothorax matching the eligibility criteria (described in the next section) were

recorded in the database of the National Taiwan University Hospital, a university teaching hospital in Taipei, Taiwan. The enrolled patients were first treated with trans-thoracic drainage

by pigtail catheter. The trans-thoracic pigtail catheter (8-French, 2.67-mm diameter) was inserted into the side affected by the pneumothorax and patients were categorized into treatment

failure and treatment success groups. Treatment failure was defined by the two following conditions: (1) persistent air leaks 72 hours after the procedure or (2) an enlarging pneumothorax on

serial chest radiographs after pigtail catheter removal under the condition of no ongoing airleaks. Treatment success was defined as no detectable pneumothorax after the pigtail catheter

was removed and a disease-free status maintained for more than one month after catheter removal. Patient characteristics including age, gender, smoking status (current smokers and

ever-smokers were classified as “smokers”, and never-smokers were classified as “nonsmokers”), and side of the pneumothorax at initial assessment were recorded. Clinical parameters,

including hemoglobin, WBC count, and renal and hepatic function, were collected from the patient charts. The Research Ethics Committee of the National Taiwan University Hospital approved

this study. Written informed consent was obtained from all subjects before the procedure, and all procedures and methods were performed in accordance with relevant guidelines and

regulations. ELIGIBILITY CRITERIA Patients were considered eligible for inclusion in the study if: (1) they had their first episode of spontaneous pneumothorax, and (2) the first chest

radiograph after the episode revealed that the rim of air in the thorax was >2 cm, compatible with the definition of a large-sized PSP according to the BTS 2010 criteria3. Additional

inclusion criteria included age between 15 and 40 years, with adequate hematological function (hemoglobin >10 g/dL, absolute neutrophil count >1.5 × 109/L, and platelets >100 × 

109/L), and normal renal and hepatic functions (serum creatinine <1 × ULN, serum glutamic-pyruvic transaminase and serum glutamic-oxaloacetic transaminase <2.5 × the upper limits of

normal). Patients were excluded if they (1) had underlying pulmonary disease, such as a congenital anomaly or lung fibrosis, (2) had an emergency condition requiring chest tube thoracostomy

or surgical exploration, such as hemothorax or tension pneumothorax, (3) had a history of previous pneumothorax, (4) had a history of an ipsilateral thoracic operation, (5) were pregnant or

lactating, or (6) had a serious concomitant illness or medical condition. ESTIMATION OF PNEUMOTHORAX SIZE We carefully reviewed the first chest radiograph that confirmed the diagnosis of

pneumothorax in every patient. Chest radiographs were retrospectively reviewed by two of the principal investigators (T-M Tsai, M-W Lin, H-C Liao, and C-Y Liu). The investigators were

blinded to the patient outcomes, and their decision was recorded after they reached a consensus. We used the Light index25, a measurement modality generally accepted in Europe, for the

estimation of pneumothorax size. The Light index is based on the proportional relationship between the diameters of a collapsed lung and its hemithorax. The estimated pneumothorax percentage

 = (1 − L3/H3) × 100; where H = hemithorax diameter and L = diameter of the collapsed lung (Fig. 2). INSERTION OF THE THORACIC PIGTAIL CATHETER Once the patient was enrolled, thoracic

drainage was immediately performed as follows. All procedures were performed by board-certified thoracic surgeons in our institute. Patients were first seated in a semi-supine position and,

after skin disinfection and field preparation, a small-bore pigtail catheter (8-French; Bioteque Corporation, I-Lan, Taiwan) was introduced into the first or second intercostal space, at the

midclavicular line, after providing local anesthesia with 2% lidocaine. After the catheter had entered the pleural space, it was fixed to the skin using sterile adhesive tape and connected

via a three-way valve to a 50-ml syringe. Air was manually aspirated until a resistance was felt and aspiration ceased. The pigtail catheter was then connected to a single-bottle

underwater-seal chest-drainage system: a rigid straw is inserted into a sterile chest bottle containing saline solution, with its tip 2-cm below the level of the solution, and the other end

of this rigid straw is connected to the pigtail catheter placed in the pleural cavity. Another rigid straw is inserted into the bottle and connected to a negative pressure suction (−10

cmH2O) device to control the drainage of the pleural cavity. Chest radiographs were obtained once before the procedure and daily after the procedure in all patients to assess treatment

results. OPERATIVE TECHNIQUES OF SALVAGE VATS VATS is a better modality than chest tube drainage for the management of unsuccessful aspiration of a PSP26. At our institution, the general

practical guidelines indicate salvage VATS for patients with recurrence or initial treatment failure of PSP. The procedure is performed in the standard fashion under general anesthesia with

double-lumen endotracheal tube intubation, with the patient in a lateral decubitus position with the ipsilateral lung deflated. We use three thoracoscopic ports: one 12-mm and two 3-mm in

diameter. A 10-mm 30-degree telescope (Karl Storz, Tuttlingen, Germany) is inserted through the 12-mm port at the 6th or 7th intercostal space, along the middle axillary line. The two 3-mm

ports are located in the 3rd or 4th intercostal space, at the anterior and posterior axillary line, respectively. The two 3-mm ports are used as working ports, allowing us to release the

pleural adhesions using electrocautery and identify the blebs. Once the blebs are identified, they are held with a 3-mm grasp, and excised with a 45-mm endoscopic stapler through the

inspection of another independent 3-mm 30-degree mini-telescope. If no blebs can be identified, blind apical stapling is done at the most suspicious area. To complete the mechanical

pleurodesis, the entire apical parietal surface is abraded by inserting a dissector with a diathermy scratch pad through the 12-mm port. Finally, a chest tube (28-French) is placed in the

apex area through the 12-mm port site. The surgical specimens are sent for routine pathological examination. STATISTICAL ANALYSIS The results were expressed as mean ± standard deviation for

continuous variables and frequency (%) for categorical variables. Differences between the failure group and the success group were compared with a two-sample _t_-test for continuous

variables, and with the chi-square test or Fisher’s exact test for dichotomous variables. Initially, we divided the patients into tertiles according to their initial pneumothorax size, and

performed a univariate analysis of the potential risk factors. To further test the robustness of our data, we created an alternative statistical model using the classification and regression

tree method. Using this model, we divided all the patients into two groups by a single cut-off point of lung collapse percentage (92.5%) and performed a multivariate logistic regression

analysis. The potential risk factors (_p_ < 0.05) in the univariate analysis and some potential clinical confounding factors were included in the multivariate logistic regression model.

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statistical analysis. The study was supported by research grants from National Taiwan University Hospital, Taipei, Taiwan (NTUH105-P02, NTUH105-003233, MS419), and the Ministry of Science

and Technology, Taiwan (104-2314-B-002-090). AUTHOR INFORMATION Author notes * Tung-Ming Tsai and Mong-Wei Lin contributed equally to this work. AUTHORS AND AFFILIATIONS * Department of

Surgery, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, 10002, Taiwan Tung-Ming Tsai, Mong-Wei Lin, Hsao-Hsun Hsu & Jin-Shing Chen *

Graduate Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, 10055, Taiwan Yao-Jen Li * Genomic Research Center, Academia Sinica, Taipei, 11529, Taiwan

Yao-Jen Li * Department of Medical Research, National Taiwan University Hospital, Taipei, 10002, Taiwan Chin-Hao Chang * Department of Traumatology, National Taiwan University Hospital,

Taipei, 10002, Taiwan Hsien-Chi Liao & Jin-Shing Chen * Division of Thoracic Surgery, Department of Surgery, Far Eastern Memorial Hospital, New Taipei City, 22060, Taiwan Chao-Yu Liu

Authors * Tung-Ming Tsai View author publications You can also search for this author inPubMed Google Scholar * Mong-Wei Lin View author publications You can also search for this author

inPubMed Google Scholar * Yao-Jen Li View author publications You can also search for this author inPubMed Google Scholar * Chin-Hao Chang View author publications You can also search for

this author inPubMed Google Scholar * Hsien-Chi Liao View author publications You can also search for this author inPubMed Google Scholar * Chao-Yu Liu View author publications You can also

search for this author inPubMed Google Scholar * Hsao-Hsun Hsu View author publications You can also search for this author inPubMed Google Scholar * Jin-Shing Chen View author publications

You can also search for this author inPubMed Google Scholar CONTRIBUTIONS Study concept and design: T.T., M.L., H.H., and J.C. Acquisition, analysis, or interpretation of data: T.T., M.L.,

Y.L., C.C., H.L., and C.L. Drafting of the manuscript: T.T., M.L., H.L., and C.L. Critical revision of the manuscript for important intellectual content: M.L., Y.L., C.C., H.H., and J.C.

Statistical analysis: T.T., Y.L., C.C., and J.C. All authors reviewed the manuscript. CORRESPONDING AUTHORS Correspondence to Hsao-Hsun Hsu or Jin-Shing Chen. ETHICS DECLARATIONS COMPETING

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and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Tsai, TM., Lin, MW., Li, YJ. _et al._ The Size of Spontaneous Pneumothorax is a Predictor of Unsuccessful Catheter Drainage. _Sci Rep_ 7,

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