Efficacy of minimally invasive surgery in diagnosis of interstitial lung disease

Introduction

The term interstitial lung disease (ILD) refers to a group of diseases characterized by inflammation and scarring of the lung parenchyma. ¹ This category consists of over 100 diseases.^2,3 A specific etiology is not found in most cases and the cause is found in only 30% of patients. ¹ The various ILD differ a lot in etiological, pathologic, therapeutic and prognostic characteristics. ⁴ ILD is a diagnostic challenge for pulmonologists due to the multiplicity of diseases that are categorized in this group and the fact that the cause is unclear in most of them.^5,6 Primary diagnostic tests consist of blood and sputum examinations and pulmonary function tests. ² Chest imaging modalities such as high-resolution computed tomography (HRCT) as well as other techniques such as bronchoalveolar lavage and transbronchial lung biopsy have contributed to more precise diagnosis.^7–9 In patients with an unknown diagnosis, a surgical lung tissue biopsy is required to reach a specific diagnosis.^3,10 Open lung biopsy (OLB) is the gold standard diagnostic method for ILD. ¹¹ However, various complications are associated with this procedure. ⁹ An alternative method is video-assisted thoracic surgery (VATS). It is less invasive than OLB, with a lower rate of complications and an equivalent diagnostic value.^9,10,12 The aims of this study were to assess the efficacy of VATS in establishing a specific ILD diagnosis, and to evaluate its safety.

Patients and methods

This retrospective study evaluated 38 patients with a diagnosis of ILD who had undergone VATS to establish a specific diagnosis at Ghaem Hospital, Mashhad University of Medical Sciences, Mashhad, Iran, between 2008 and 2013. There were 19 males and 19 females, with a mean age of 47.73 years (range 22 to 79 years). Inclusion criteria were clinically and radiologically suspected ILD that required biopsy by means of VATS to specify the diagnosis, and the patient’s agreement to participate in the study. Exclusion criteria were clinical and radiological features inconsistent with a diagnosis of ILD, no need for biopsy via VATS, and a patient’s reluctance to participate in the study. The study was approved by Mashhad University of Medical Sciences institutional review board and regional committee for ethics.

Preoperative evaluations including cardiac and pulmonary assessments were performed in all patients. The proper site for biopsy was determined based on HRCT results and intraoperative findings. Biopsy was carried out in the area where macroscopic normal and pathologic parenchymal regions were adjacent to each other. Biopsy was performed using an Endo GIA stapler (Covidien Co., Dublin, Ireland). Data recorded in forms prepared for this study included age, sex, clinical symptoms, HRCT diagnostic findings, complications of surgery, operation duration, chest drain withdrawal time, postoperative hospital stay, hospital mortality, and specific diagnosis of the disease. Data were analyzed by SPSS version 16 (SPSS, Inc., Chicago, IL, USA), and relevant frequencies and averages are reported.

Results

Presenting clinical symptoms were dyspnea in all 38 patients, cough in 32 (84.2%), cyanosis in 31 (81.5%), chest pain in 5 (13.1%), and hemoptysis in 5 (13.1%). HRCT findings were reticular patterns in 30 (78.9%) patients, consolidations in 7 (18.4%), ground glass opacities in 11 (28.9%), and interstitial thickening and nodules in 9 (23.6%). Surgical complications included 5 (13.1%) cases of persistent air leak and 2 (5.2%) of wound infection, which were managed conservatively. No hospital death occurred in our patients. The average operation duration was 50 min. The mean time for chest drain withdrawal was 4 days and postoperative hospitalization was 5 days. A definite diagnosis was achieved in 36 (94.74%) patients. The final diagnoses are shown in Table 1. The most prevalent diagnosis was usual interstitial pneumonia in 9 (23.68%) patients. A specific diagnosis was not achieved in 2 (5.26%) of the 38 patients after VATS.

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Table 1.

Final diagnosis after video-assisted thoracic surgery in patients with interstitial lung disease.

Diagnosis	No. of patients
Usual interstitial pneumonia	9 (23.68%)
Bronchiolitis obliterans organizing pneumonia	5 (13.15%)
Nonspecific interstitial pneumonia	5 (13.15%)
Hypersensitivity pneumonia	3 (7.89%)
Silicosis and pneumoconiosis	2 (5.26%)
Sarcoidosis	6 (15.78%)
Anthracosis	1 (2.63%)
Wegener’s disease	3 (7.89%)
Idiopathic pulmonary hemosiderosis	2 (5.26%)
Alveolar hemorrhage	1 (2.63%)
No diagnosis	2 (5.26%)

Discussion

ILD, also called diffuse parenchymal lung disease, consists of a vast group of diseases that involve the lung interstitium.^13,14 Great progress has been made in achieving a more precise diagnosis with new imaging techniques and minimally invasive methods such as bronchoalveolar lavage, which are preferred to avoid surgery as far as possible.^1,15 However, despite undergoing different diagnostic procedures, a definite diagnosis cannot be achieved in some patients. ¹⁶ In these patients, a biopsy of the lung parenchyma is required, and specialists must evaluate the risks and benefits of surgery and make the final decision. ¹⁷ Preoperative HRCT is a favorable method for finding the correct locations for biopsy. ¹⁸ We used preoperative HRCT results and intraoperative findings to determine the locations for biopsy in this study.

OLB is considered the gold standard, leading to a specific diagnosis in more than 90% of patients. ¹² However, 9% to 50% morbidity and up to 27% mortality rates have been reported for OLB in ILD patients. ¹⁰ Thus less invasive techniques are preferred. One alternative method is VATS. In our study, VATS had a hospital mortality rate of 0% and complications included 5 cases of persistent air leak and 2 cases of wound infection, which were managed conservatively. Yamaguchi and colleagues ¹⁰ also reported no mortality after VATS in 30 patients, with respiratory failure in 2 and prolonged air leak in one. Zegdi and colleagues ¹² performed VATS in 64 patients with diffuse infiltrative lung disease. Postoperative complications included 5 discrete pneumothoraces that resolved spontaneously, 1 prolonged air leak, and 1 hemothorax that needed reoperation. The mortality rate was 4.7% due to preoperatively debilitated patients who succumbed to progression of respiratory failure and septic shock. Careful selection of patients for VATS is important because it results in fewer complications. ¹⁹ Previously, the use of thoracoscopy was restricted to diseases of the pleura, due to limited resources and equipment, but technological advances in the field of endoscopic surgery have led to its widespread use in different lung diseases. ² VATS is almost as accurate as OLB in the diagnosis of interstitial lung diseases. ⁹ In our study, a definitive histologic diagnosis was reached in 94.7% of patients. This agrees with other reports of a specific diagnosis in 87% to 96.8% of cases.^1,2,5,19 These values are close to the OLB success rate in reaching the final diagnosis in ILD patients. The most common histologic diagnosis in our study was usual interstitial pneumonia (9 patients, 23.68%) followed by sarcoidosis (6 patients, 15.78%).

In a study by Bensard and colleagues ² who compared VATS with OLB, VATS was similar to OLB in terms of operative time, number of biopsies per patient, and amount of tissue obtained. The diagnostic accuracy was also close: 95% for VATS (94.7% in our study) and 100% for OLB; however, OLB was associated with a significantly longer duration of pleural drainage and hospital stay. No death occurred in the VATS group (as in our study) compared to one death in the OLB group, and there was a significantly higher incidence of major complications in the OLB group; 4 of 21 patients who underwent OLB experienced major complications including pulmonary embolus, bronchopleural fistula, and postoperative hemorrhage requiring blood transfusion and surgical reexploration. No major complications occurred in our patients. Ayed and colleagues ⁵ found that VATS resulted in significantly shorter operative time and hospital stay compared to OLB. Diagnostic accuracy was similar: 93% for VATS and 97% for OLB. Two deaths occurred in the OLB group and none in the VATS group. Six out of 29 patients in the OLB group and 3 out of 32 in the VATS group experienced complications. In the OLB group, there was 1 air leakage, 2 respiratory failures, 1 pulmonary embolism, and 2 cases of atelectasis; in the VATS group, all 3 were air leakage. Similar to our study, the complications of VATS were not as severe as those seen after OLB. VATS does not increase the duration of surgery, according to Bensard and colleagues ² (38 min for OLB and 46 min for VATS). A similar result was found in our study (50 min). This was attributed to advances in equipment and endoscopic techniques as well as more experience gained by thoracic surgeons in the use of these techniques over the years. VATS decreases hospitalization because of the smaller incisions, less consumption of analgesics, and faster withdrawal of the thoracic drain.^1,5 We concluded that VATS is a safe minimally invasive method that is associated with a low rate of minor complications and is close to OLB in diagnostic value, However, employment of this method depends on the decision of specialists who evaluate the related risks and benefits in these patients.