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ORIGINAL ARTICLE
Year : 2019  |  Volume : 22  |  Issue : 9  |  Page : 1292-1297

Prolonged air leak after video-assisted thoracoscopic surgery in patients with primary spontaneous pneumothorax


Department of Thoracic Surgery, Ege University, Faculty of Medicine, Izmir, Turkey

Date of Acceptance22-May-2019
Date of Web Publication6-Sep-2019

Correspondence Address:
Dr. ÷ Kavurmaci
Department of Thoracic Surgery, Health Sciences University İzmir Bozyaka Training and Research Hospital, İzmir
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_86_18

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   Abstract 


Background: Patients who have undergone a lung resection owing to primary spontaneous pneumothorax (PSP) may develop prolonged air leak (PAL) during the postoperative period. The present study investigates potential risk factors associated with postoperative PAL in patients who were operated on for PSP. Materials and Methods: Patients who underwent operations for PSP between January 2004 and November 2017 were investigated retrospectively. Patients who developed postoperative PAL constituted Group 1, and patients without PAL formed Group 2. A comparison of the two groups was made to identify potential risk factors for the development of prolonged air leak. Results: Of the total 79 patients who underwent operations, 18 (22.78%) developed prolonged air leak. All of the patients in Group 1 were male, and the mean age of this group was 23.72 ± 5.76 (18–36) years. Of the patients in Group 2, 51 (83.61%) were male and 10 (16.39%) were female, and the mean age of this group was 25.81 ± 5.91 (17–39) years. There was no statistically significant difference noted between the two groups regarding the investigated factors including age, gender, the total number of previous episodes, number of ipsilateral episodes, number of contralateral episodes, the preferred treatment method for the last episode, smoking status, computerized tomography findings, or the presence of a preoperative air leak. Conclusions: PAL is the most common complication associated with PSP surgeries. Although several factors may affect PAL development, no definite conclusion could be drawn concerning the investigated risk factors. We believe that similar studies may contribute to the care of this rare patient population.

Keywords: Primary spontaneous pneumothorax, prolonged air leak, surgical treatment


How to cite this article:
Kavurmaci ÷, Akcam T I, Ergonul A G, Cagirici U, Cakan A. Prolonged air leak after video-assisted thoracoscopic surgery in patients with primary spontaneous pneumothorax. Niger J Clin Pract 2019;22:1292-7

How to cite this URL:
Kavurmaci ÷, Akcam T I, Ergonul A G, Cagirici U, Cakan A. Prolonged air leak after video-assisted thoracoscopic surgery in patients with primary spontaneous pneumothorax. Niger J Clin Pract [serial online] 2019 [cited 2019 Nov 13];22:1292-7. Available from: http://www.njcponline.com/text.asp?2019/22/9/1292/266173




   Introduction Top


Primary spontaneous pneumothorax (PSP) is defined as the deposition of air in the pleural cavity in the absence of underlying pulmonary disease. The yearly incidence of PSP was reported as (18–28)/100,000 in men and (1.2–6)/100,000 in women,[1] and approximately, (1.2–18)/100,000 in the general population.[2],[3],[4] Treatment of PSP depends on factors such as the patient's clinical status, the size of the pneumothorax, and any history of previous episodes.[3],[5],[6] Treatment options include monitoring under oxygen therapy, simple aspiration, tube thoracostomy, and lung operation.[3],[5] Indications for operation are well-established, and surgery is recommended for patients presenting with recurrent pneumothorax and for select patients who develop prolonged air leak (PAL) after a tube thoracostomy.[5] Although there are contradictory data in the literature, reports indicate that (2–5.6)% of patients develop postoperative PAL.[7],[8] Persistent air leaks in spite operations in patients operated on for PAL is a particularly challenging situation for both the patient and the surgeon.

Although there have been several studies that have investigated postoperative early- or late-term recurrence, very few studies have addressed PAL and the associated risk factors. The present study aims to identify the potential risk factors in PSP patients who have experienced prolonged postoperative air leak.


   Materials and Methods Top


The medical files of patients who underwent operations for PSP at our clinics between January 2004 and November 2017 were investigated retrospectively. All patients gave written informed consent before treatment. A PSP diagnosis was made after a detailed clinical, radiological evaluation and considering the histopathological findings on the sample during operation. Patients who were found to have a secondary spontaneous pneumothorax (SSP) from these evaluations were excluded from this study. All of the patients included in this study had been evaluated by computerized tomography (CT) imaging before the operation, and patients without available CT images were excluded. Only the patients who had undergone video-thoracoscopic wedge resection and pleural abrasion were included in this study. All patients had been intubated using a double-lumen endotracheal tube and operated on in the lateral decubitus position. The number of ports (1–3 ports) used during video-thoracoscopic surgery was not standardized, and the choice of port number and localization was left to the discretion of the surgeon. The operation was initiated by filling the thoracic cavity with physiological saline and identifying the air leak. In patients found to have air leakage, the concerned region was removed with wedge resection, while an apical wedge resection was performed in patients without air leakage. The bullae-bleb structures were identified in other regions of the lungs were also excised in all patients. The operation was completed after a pleural abrasion and re-checking for air leakage. A pleural abrasion was performed in all patients and involved abrasion of the parietal pleura by tamponade placed on the tip of an endograsper. Abrasion was continued until apetechial bleeding locus was achieved on the parietal pleura.

A cut-off value of 7 days was considered for postoperative PAL development. Patients who developed postoperative PAL constituted Group 1, and those without PAL were included in Group 2. The demographic characteristics of the patients, including age, gender, smoking status, and the number of previous pneumothorax episodes, as well as computerized tomography reports, operation reports, duration of drainage, and histopathological investigation findings, were recorded. A t test was used for the analysis of the numerical data such as age, smoking status (packs/year), number of previous episodes, number of ipsilateral episodes, and number of contralateral episodes. The most recent treatment method preferred in each patient (such as monitoring under oxygen-tube thoracostomy-wedge resection) was analyzed after grouping. On basis of the CT findings, the patients were included in the analyses after being classified as those with bullae-bleb structures and those with only apical irregularities in the absence of bullae-bleb structures.

Preoperative findings were grouped on the basis of the presence of air leak. On basis of the leak test performed before a resection, patients were classified as those with and those without identified leak localization. Chi-square tests were used for the statistical analysis of all non-numeric data such as gender, the most recent treatment, tomography findings, and identification of preoperative air leak. SPSS version 21.0 software (IBM Corp, Armonk, NY, USA) was used for statistical analyses of the study data.

Patients who developed postoperative PAL were treated with an “autologous blood-patch pleurodesis'' procedure, which involved the administration of 100 cc blood collected from a peripheral vein of the patient into the pleural cavity through a thoracic drainage tube. After the blood was given into the pleural cavity through the thoracic drainage tube, the patient's position was changed to ensure the spread of blood across the entire lung surface. Throughout the procedure, the thoracic drainage tube was left in the form of a loop to ensure continuous air drainage.


   Results Top


Of the total 79 patients included in this study, 69 (87.35%) were men and 10 (12.65%) were women. The mean age of the men and women was 24.73 ± 5.60 (17–39) years and 29.5 ± 6.57 (23–36) years, respectively. Of the total, 36 (45.56%) presented with right and 43 (54.44%) presented with left hemothorax. Of the total 79 patients, 67 (84.81%) were operated on for recurrent pneumothorax, and 12 (15.12%) underwent operations after the development of PAL during the treatment of their first pneumothorax episode by tube thoracostomy. A review of the medical histories of patients operated on for recurrent pneumothorax indicated that 67 patients experienced a total of 181 pneumothorax episodes and that 151 (83.42%) of those were ipsilateral with the last episode, whereas the remaining 30 (16.57%) were contralateral episodes. The most recent treatments used in the 67 patients presenting with recurrent pneumothorax were tube thoracostomy in 53 (79.10%), video-thoracoscopic wedge resection in eight (11.94%), and monitoring under oxygen in six (8.95%) patients [Table 1].
Table 1: Demographic characteristics of Group 1 and Group 2 patients

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Group 1 comprised 18 (22.78%) patients who had a postoperative PAL, and Group 2 included 61 (77.22%) patients without postoperative PAL development. All of the patients in Group 1 were men and their mean age was 23.72 ± 5.76 (18–36) years. Of the patients in Group 2, 51 (83.61%) were men and 10 (16.39%) were women, with mean ages of 25.09 ± 5.56 (17–39) years for men and 29.5 ± 6.57 (23–36) years for women. The mean age of the entire group was 25.81 ± 5.91 (17–39) years. In Group 1, three (16.66%) patients were operated on owing to PAL development after a tube thoracostomy, and 15 (83.34%) patients were operated on owing to recurrent pneumothorax. In Group 2, nine (14.75%) patients were operated on owing to PAL and 52 (85.25%) patients were operated on owing to recurrence. When the previous episodes in 15 patients operated owing to recurrence in Group 1 were investigated, it was noted that there were a total number of 43 pneumothorax episodes, 40 (93.02%) of these were ipsilateral with last episode, andthree (6.98%) of them were contralateral with the last episode. The preferred treatment for the most recent pneumothorax episodes of these patients was monitoring under oxygen in one (6.66%) patient, operation in three (19.99%) patients, and tube thoracostomy in 11 (73.34%) patients. There were 52 patients in Group 2, who were operated owing to recurrence pneumothorax. There were 138 pneumothorax episodes, 111 (80.43%) of them were ipsilateral with the last pneumothorax episode, and 27 (19.56%) of them were contralateral with last pneumothorax episode. The preferred treatment for the most recent pneumothorax episodes of these patients was monitoring under oxygen in five (9.62%) patients, operation in five (9.62%) patients, and tube thoracostomy in 42 (80.76%) patients.

The mean duration of smoking in Groups 1 and 2 was 3.77 ± 4.12 (0–15) packs/year and 3.68 ± 3.98 (0-17) packs/year, respectively. CT findings of the patients in Group 1 indicated that eight (44.44%) patients had apparent bullae-bleb structures, whereas 10 (55.56%) patients had no bullae-blebs, but only parenchymal irregularities in the lung apex. The CT findings of the patients in Group 2 showed that 30 (49.18%) patients had apical irregularities, and 31 (50.82%) patients had apparent bullae-bleb formations.

The results of preoperative air leak tests indicated that the air leak location could be identified only in two (11.11%) patients in Group 1, and the leak localization was unknown for the remaining 16 (88.89%) patients. In Group 2, the air leak location could be identified only in 11 (18.03%) patients, and it was unknown for the remaining 50 (81.97%) patients.

In Groups 1 and 2, the drainage tube was removed 8.83 ± 3.16 (7–19) days and 3.88 ± 1.19 (2–6) days after surgery, respectively. The mean duration of hospital stay after surgery was 9.00 ± 2.14 (7–15 days) in Group 1 and 5.00 ± 2.00 (2–14) days in Group 2.

Statistical analyses were carried out to compare the data collected in the two study groups to identify their potential effects on prolonged air leakage. The t test was used for age; Mann-Whitney test was used for smoking history and previous pneumothorax episodes. The Chi-square test was used for gender, CT findings, preoperative finding, previous attack treatment, and cause of operation. The analysis revealed that factors such as age (p:0.188), gender (p:0.066), total number of previous episodes (p:0.861), number of ipsilateral episodes (p:0.456), number of contralateral episodes (p:0.174), treatment preferred for the last episode (such as tube thoracostomy and monitoring under oxygen) (p:0.331), smoking history (p:0.915), CT findings (p:0.635), and preoperative air leak presence (p:0.486) had no significant effect on PAL development [Table 2].
Table 2: Possible risk factors investigated for prolonged air drainage and P values obtained as a result of statistical analysis

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In this study, blood-patch pleurodesis were applied to patients for treatment of PAL. Of the total 18 patients who developed PAL, nine (50%) underwent 19 blood-patch pleurodesis procedures in total. In the patients who underwent blood-patch pleurodeses, air leakage was terminated after the initial application in four (44.44%) patients, after the second application in four (44.44%) patients, and after the third application in one (11.12%) patient. A long-term follow-up of the patients who received a blood-patch showed that only one (11.12%) experienced a recurrence 1 month after treatment, and the remaining eight (88.88%) patients had no recurrence over a mean follow-up of 14.11 ± 10.72 (1–35) months.


   Discussion Top


The term pneumothorax was used for the first time by Itard in 1803, and later by Laennec in 1819.[9] As most cases of pneumothorax at the time were associated with tuberculosis, the later awareness of primary cases was made by Kjaergaard et al.[10] in 1932, who used the term PSP, which was defined as the spontaneous deposition of air into the pleural cavity in the absence of an underlying pulmonary disease.[1],[2],[3],[4],[5] Although the pathogenesis is still to be clarified, air leakages are thought to originate from the sub-pleural bullae and blebs and are mostly localized in the lung apex.[11],[12] The optimal management of PSP is still a matter of debate and depends on a combination of several factors such as the number of episodes, the size of pneumothorax, and clinical signs.[11],[12] Although the first episodes are generally managed by methods such as medical treatment, simple aspiration, or tube thoracostomy, surgical treatment becomes an option in the presence of recurrence, persistent air leakage, hemopneumothorax, bilateral pneumothorax, and occupational obligation.[2],[5],[11],[12],[13]

There are a number of commonly accepted approaches to the surgical treatment of PSP.[6],[7],[8] In general, a resection of the bullae and bleb structures is combined with a pleurodesis procedure.[6],[7],[8],[13],[14],[15] Although some studies have used agents such as talcum powder and minocycline for pleurodesis, there are also studies that recommend pleural abrasion or partial/total pleurectomy procedures.[6],[7],[8],[13],[14],[15]

The success of PSP surgery is evaluated from the calculated postoperative recurrence rates in many studies.[13],[14],[15] However, there are very few studies evaluating postoperative PAL development.[7] Several studies in the literature have reported postoperative PAL as the most common complication, having been encountered in 2–17.6% of this patient population.[6],[7],[8],[16] The considerable difference in the PAL incidence reported in previous studies can be attributed to the differences in the cut-off points for the diagnosis of prolonged air leakage (3–7 days) and also to the differences in the preferred surgical procedures (wedge resection and wedge resection + pleurodesis).[6],[7],[8],[16] Furthermore, some of the previous studies include patients with SSP in their patient populations.[8] In a previous study that investigated risk factors for PAL development after a spontaneous pneumothorax, a total of 2,292 patients were analyzed, and postoperative PAL was reported in 9.7% of these patients.[8] In another study that addressed the efficacy of minocycline-picibanil (OK-432) pleurodesis for the prevention from PAL developing after PSP surgery, PAL was detected in 7.3% of the total number of 1,083 patients with PSP.[7] Although similar surgical procedures were followed, the rate of PAL in this study (22.78%) was higher than the rates reported by previous studies in the literature. Such a high rate of PAL development, in spite the exclusion of the patients with SSP from the study, caused us to question our current surgical approach. All patients included in this study underwent a video-thoracoscopic wedge resection or pleural abrasion. Moreover, no material (such as endoscopic stapler cuff and air leak cover) was used to support the staple lines. The surgical procedure implemented at our clinic is a commonly accepted procedure in the literature and has been addressed in various studies.[6],[17] In studies of L. Lang-Lazdunski et al.[6] and Casadio C. et al.,[17] who followed a similar surgical procedure, PAL was the most common postoperative complication, reported in 14.8% and 4.3% of the patients in those studies, respectively. It may seem reasonable to consider that the high rate of PAL in our study (22.78%) may be a result of our pleurodesis method (abrasion using endograsper). In spite that in a previous case-series of 263 patients reported by Park et al.,[18] neither the rate of recurrence nor the duration of drainage was found to be significantly different between patients who did or did not undergo pleural abrasion. In a study performed by Chen JS. et al.,[16] however, the preoperative use of minocycline in the absence of pleural abrasion significantly reduced the rate of the postoperative PAL. In spite these confusing results about peroperative pleurodesis, and considering the potential thoracic operations that we may perform in the future, we try to avoid chemical pleurodesis as much as possible in our clinical practice. We plan to reduce the rate of PAL by increasing the use of support materials such as air leak covers or stapler cuffs.[19]

The potential risk factors related to PAL, as the most common complication of PSP surgery, were previously investigated in a study conducted by Jiang L. et al.[8] In all the patients included in the study, 23 potential risk factors were investigated, and only four of these were found to have a significant impact on PAL development. These factors were reported to be “old age, American Society of Anesthesiology (ASA) score, implementation of bilateral procedure and bullae diameter.”[8] Gender, smoking history, and the reason for the operation had no statistically significant effect in that study either. The cause of the differences in the results of that study, which also included SSP cases, can be understood when the patient groups are reviewed in more detail. Only patients with PSP were included in the present study, and so both study groups had a similar age distribution. Moreover, our groups included also young patients with no comorbidities, and we did not calculate the ASA score. As the study included patients with PSP only, the bullae-bleb structures did not show significant size differences and no bullae formation was noted in some of the patients, either in preoperative tomographic images or during perioperative explorations. Instead, patients were classified according to the presence of bullae-blebs or apical irregularities in their tomographic images. This classification did not highlight a significant difference regarding PAL. Different from Jiang L. et al.'s study,[8] we also classified our patients according to the number and side of the previous episodes, the type of the most recent therapy, and the presence of preoperatively identified air leakages. This classification, according to the anticipation that PAL development may be associated with a wedge resection performed at an incorrect region of the parenchyma, also did not result in a significant difference. Similar results were also obtained in patients from whom the bullae were resected, in spite no air leak was detected.

As there are very few cases in the literature, we have only limited knowledge on the optimal treatment of postoperative PAL in PSP patients.[5],[7] Hoe CH. et al.[7] reported that OK-432 or minocycline pleurodesis may be preferred in this patient group, associating OK-432 with higher efficacy. We have implemented autologous blood-patch pleurodesis procedures rather than using a chemical agent for the treatment of patients who developed postoperative PAL. The autologous blood-patch procedure is a widely accepted approach to the management of patients with both spontaneous pneumothorax and postoperative PAL.[20],[21] In this study, we intended to minimize the potential side effects of chemical pleurodesis using the patient's own blood for the pleurodesis procedure. Air leakage stopped in four patients after the first blood-patch pleurodesis procedure. In total, nine patients were treated with blood-patch pleurodesis, and none of these patients experienced complications resulting from the procedure. Over a follow-up period of approximately 14 months, only one patient developed recurrent pneumothorax.

PAL is the most common complication encountered after spontaneous pneumothorax operations.[6],[7],[8] Ongoing air leakage after the operation, particularly in PSP patients operated on for PAL, is a concern both for patients and their relatives. In the present study, we aimed to identify the risk factors associated with this commonly encountered complication in our clinics but could find no significant effect of any factor on PAL. At this point, we plan to pay closer attention to operational variables and to carry out additional research in this area. We believe that additional large-scale studies are required to address this significant complication, and in this regard, this preliminary study may serve as a pioneer for similar studies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
   References Top

1.
Melton LJ, Hepper NC, Offord KP. Incidence of spontaneous pneumothorax in Olmsted County, Minnesota: 1950–1974. Am Rev Respir Dis 1987;29:1379-82.  Back to cited text no. 1
    
2.
Noppen M. Spontaneous pneumothorax: Epidemiology, pathophysiology and cause Eur Respir Rev 2010;19:217-9.  Back to cited text no. 2
    
3.
Hoyos de A, Fry WA. Pneumothorax. In: Shields TW, LoCicero J, Reed CE, Feins RH, editors. General Thoracic Surgery. 7th ed. Philadelphia: Lippincott Williams & Wilkins; 2009. p. 739-61.  Back to cited text no. 3
    
4.
Jantz MA, Anthony VB. Pathophysiology of the pleura. Respiration 2008;75:121-33.  Back to cited text no. 4
    
5.
MacDuff A, Arnold A, Harvey J. Management of spontaneous pneumothorax: British Thoracic Society Pleural Disease Guideline 2010. Thorax 2010;65(Suppl 2):ii18-31.  Back to cited text no. 5
    
6.
Lang-Lazdunski L, Chapuis O, Bonnet PM, Pons F, Jancovici R. Videothoracoscopic bleb excision and pleural abrasion for the treatment of primary spontaneous pneumothorax: Long-term results. Ann Thorac Surg 2003;75:960-5.  Back to cited text no. 6
    
7.
How CH, Tsai TM, Kuo SW, Huang PM, Hsu HH, Lee JM, et al. Chemical pleurodesis for prolonged postoperative air leak in primary spontaneous pneumothorax. J Formos Med Assoc 2014;113:284-90.  Back to cited text no. 7
    
8.
Jiang L, Jiang G, Zhu Y, Hao W, Zhang L. Risk factors predisposing to prolonged air leak after video-assisted thoracoscopic surgery for spontaneous pneumothorax. Ann Thorac Surg 2014;97:1008-13.  Back to cited text no. 8
    
9.
Laennec RT. Traite' Du Diagnostic des Maladies des Poumons et du Coeur. Tome Second, Paris: Brosson and Chaud; 1819.  Back to cited text no. 9
    
10.
Kjærgaard H. Spontaneous pneumothorax in the apparently healthy. Acta Med Scand 1932;43:1e159.  Back to cited text no. 10
    
11.
Hsu HH, Chen JS. The etiology and therapy of primary spontaneous pneumothoraces. Expert Rev Respir Med 2015;9:655-65.  Back to cited text no. 11
    
12.
Tschopp JM, Bintcliffe O, Astoul P, Canalis E, Driesen P, Janssen J, et al. ERS task force statement: Diagnosis and treatment of primary spontaneous pneumothorax. Eur Respir J 2015;46:321-35.  Back to cited text no. 12
    
13.
Baumann MH, Strange C, Heffner JE, Light R, Kirby TJ, Panacek EA, et al. Management of spontaneous pneumothorax: An American College of Chest Physicians Delphi consensus statement. Chest 2001;119:590-602.  Back to cited text no. 13
    
14.
Cardillo G, Carleo F, Giunti R, Carbone L, Mariotta S, Salvadori L, et al. Videothoracoscopic talc poudrage in primary spontaneous pneumothorax: A single-institution experience in 861 cases. J Thorac Cardiovasc Surg 2006;131:322-8.  Back to cited text no. 14
    
15.
Cardillo G, Facciolo F, Giunti R, Gasparri R, Lopergolo M, Orsetti R, et al. Videothoracoscopic treatment of primary spontaneous pneumothorax: A 6-year experience. Ann Thorac Surg 2000;69:357-61.  Back to cited text no. 15
    
16.
Chen JS, Hsu HH, Kuo SW, Tsai PR, Chen RJ, Lee JM, et al. Effects of additional minocycline pleurodesis after thoracoscopic procedures for primary spontaneous pneumothorax. Chest 2004;125:50-5.  Back to cited text no. 16
    
17.
Casadio C, Rena O, Giobbe R, Rigoni R, Maggi G, Oliaro A. Stapler blebectomy and pleural abrasion by video-assisted thoracoscopy for spontaneous pneumothorax. J Cardiovasc Surg (Torino) 2002;43:259-62.  Back to cited text no. 17
    
18.
Park JS, Han WS, Kim HK, Choi YS. Pleural abrasion for mechanical pleurodesis in surgery for primary spontaneous pneumothorax: Is it effective? Surg Laparosc Endosc Percutan Tech 2012;22:62-4.  Back to cited text no. 18
    
19.
Sakamoto K, Takei H, Nishii T, Maehara T, Omori T, Tajiri M, et al. Staple line coverage with absorbable mesh after thoracoscopic bullectomy for spontaneous pneumothorax. Surg Endosc 2004;18:478-81.  Back to cited text no. 19
    
20.
Cagirici U, Sahin B, Cakan A, Kabayas H, Budunelli T. Autologous blood patch pleurodesis in spontaneous pneumothorax with persistent air leak. Scand Cardiovasc J 1998;32:75-8.  Back to cited text no. 20
    
21.
Shackloth M, Poullis M, Page R. Autologous blood pleurodesis for treating persistent air leak after lung resection. Ann Thorac Surg 2001;71:1402-3.  Back to cited text no. 21
    



 
 
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