Diagnostic workup for diffuse parenchymal lung disease: schematic flowchart, literature review, and pitfalls

Multidisciplinary Approach to the Diagnosis of Idiopathic Interstitial Pneumonias: Focus on the Pathologist's Key Role

Idiopathic Interstitial Pneumonias (IIPs) are a heterogeneous group of the broader category of Interstitial Lung Diseases (ILDs), pathologically characterized by the distortion of lung parenchyma by interstitial inflammation and/or fibrosis. The American Thoracic Society (ATS)/European Respiratory Society (ERS) international multidisciplinary consensus classification of the IIPs was published in 2002 and then updated in 2013, with the authors emphasizing the need for a multidisciplinary approach to the diagnosis of IIPs. The histological evaluation of IIPs is challenging, and different types of IIPs are classically associated with specific histopathological patterns. However, morphological overlaps can be observed, and the same histopathological features can be seen in totally different clinical settings. Therefore, the pathologist's aim is to recognize the pathologic-morphologic pattern of disease in this clinical setting, and only after multi-disciplinary evaluation, if there is concordance between clinical and radiological findings, a definitive diagnosis of specific IIP can be established, allowing the optimal clinical-therapeutic management of the patient.

Assessable and interpretable sensitivity analysis in the pattern graph framework for nonignorable missingness mechanisms

The pattern graph framework solves a wide range of missing data problems with nonignorable mechanisms. However, it faces two challenges of assessability and interpretability, particularly important in safety-critical problems such as clinical diagnosis: (i) How can one assess the validity of the framework's a priori assumption and make necessary adjustments to accommodate known information about the problem? (ii) How can one interpret the process of exponential tilting used for sensitivity analysis in the pattern graph framework and choose the tilt perturbations based on meaningful real-world quantities? In this paper, we introduce Informed Sensitivity Analysis, an extension of the pattern graph framework that enables us to incorporate substantive knowledge about the missingness mechanism into the pattern graph framework. Our extension allows us to examine the validity of assumptions underlying pattern graphs and interpret sensitivity analysis results in terms of realistic problem characteristics. We apply our method to a prevalent nonignorable missing data scenario in clinical research. We validate and compare our method's results of our method with a number of widely-used missing data methods, including Unweighted CCA, KNN Imputer, MICE, and MissForest. The validation is done using both boot-strapped simulated experiments as well as real-world clinical observations in the MIMIC-III public dataset.

Comparison of the diagnostic yield of transbronchial lung biopsies by forceps and cryoprobe in diffuse parenchymal lung disease

Background

Transbronchial lung cryobiopsy (TBLC) in the diagnosis of diffuse parenchymal lung disease (DPLD) has shown a promising yield in recent times, with low post-procedural mortality and morbidity.

Objectives

To compare the yield of TBLC and conventional transbronchial forceps lung biopsy (TBLB).

Methods

A prospective study was carried out in patients with DPLD over a period of 1 year in a tertiary respiratory care institute in New Delhi, India. All 87 patients enrolled underwent both TBLB and TBLC. The procedures were performed in the bronchoscopy suite under conscious sedation and local anaesthesia, with an attempt to take a minimum of three biopsy specimens by conventional TBLB followed by TBLC. A 1.9 mm cryoprobe with a freezing time of 4 - 5 seconds was used. An Arndt endobronchial blocker was used to control bleeding along with locally administered medications.

Results

TBLB and TBLC led to a definitive diagnosis in 27 (31.0%) and 69 (79.3%) cases, respectively. The commonest diagnoses were hypersensitivity pneumonitis, sarcoidosis and pulmonary tuberculosis. TBLC led to additional diagnoses in 42 cases (48.3%). Pneumothorax was observed in 12 cases (13.8%), and moderate bleeding occurred in 63 (72.4%). There were no procedure-related deaths.

Conclusion

TBLC had a better diagnostic yield than conventional TBLB in DPLD. It has the potential to become a safe day-care procedure in a resource-limited setting, if certain precautions are taken.

Study synopsis

What the study adds. Compared with transbronchial forceps lung biopsy, transbronchial lung cryobiopsy (TBLC) led to additional diagnoses in 42 (48.3%) of 87 patients with clinicoradiological features of diffuse parenchymal lung disease. Pneumothorax was observed in 12 cases (13.8%) and moderate bleeding in 63 (72.4%). TBLC without rigid bronchoscopy or advanced airway devices under conscious sedation had a good diagnostic yield with an acceptable adverse events profile.Implications of the findings. TBLC under conscious sedation is not resource intensive and can be carried out in settings with limited resources.

Diagnostic yield and safety of transbronchial lung cryobiopsy and surgical lung biopsy in interstitial lung diseases: a systematic review and meta-analysis

INTRODUCTION

Transbronchial lung cryobiopsy (TBLC) is increasingly being used as an alternative to video-assisted thoracoscopic surgery (VATS) biopsy to establish the histopathologic pattern in interstitial lung disease (ILD).

METHODS

A systematic literature search of the PubMed and Embase databases, from October 2010 to October 2020, was conducted to identify studies that reported on diagnostic yield or safety of VATS or TBLC in the diagnosis of ILD.

RESULTS

43 studies were included. 23 evaluated the diagnostic yield of TBLC after multidisciplinary discussion, with a pooled diagnostic yield of 76.8% (95% confidence interval (CI) 70.6-82.1), rising to 80.7% in centres that performed ≥70 TBLC. 10 studies assessed the use of VATS and the pooled diagnostic yield was 93.5% (95% CI 88.3-96.5). In TBLC, pooled incidences of complications were 9.9% (95% CI 6.8-14.3) for significant bleeding (6.9% for centres with ≥70 TBLC), 5.6% (95% CI 3.8-8.2) for pneumothorax treated with a chest tube and 1.4% (95% CI 0.9-2.2) for acute exacerbation of ILD after TBLC. The mortality rates were 0.6% and 1.7% for TBLC and VATS, respectively.

CONCLUSIONS

TBLC has a fairly good diagnostic yield, an acceptable safety profile and a lower mortality rate than VATS. The best results are obtained from more experienced centres.

Safety of performing transbronchial lung cryobiopsy on hospitalized patients with interstitial lung disease

INTRODUCTION

Transbronchial lung cryobiopsy (TBLC) has become a popular option for tissue diagnosis of interstitial lung disease (ILD), however reports vary regarding the safety of this procedure. Herein, we evaluate the safety of transbronchial cryobiopsy in hospitalized patients, comparing adverse events to outpatient procedures.

METHODS AND MEASUREMENTS

This is a single center, retrospective chart review of all TBLC performed for suspected ILD between November 2013 and March 2017. Biopsies were performed by a board certified interventional pulmonologist or interventional pulmonology fellow using a two-scope technique.

RESULTS

One hundred fifty-nine cryobiopsies were performed for the diagnosis of ILD. Rates of adverse events are as follows: pneumothorax 11%, persistent air leak 1.3%, moderate-severe bleeding 3.8%, ICU transfer within 48 h 3.1%, and all cause 30-day mortality 1.9%. No deaths were attributed to the procedure. Comparing adverse events between hospitalized patients and outpatients, rates of pneumothorax were 24% vs 9.9%, persistent air leak 5.9% vs 0.7%, ICU transfer 12% vs 2.1%, and 30-day mortality 5.9% vs 1.4%. However, no differences were statistically significant.

CONCLUSION

Practitioners should recognize that while cryobiopsies are a high-yield, safe, and cost-effective alternative to surgical lung biopsy, not all procedures carry the same risk profiles. Hospitalized patients may have a greater propensity for pneumothorax, persistent air leak, transfer to the ICU, and 30-day mortality.

A Single US Center Experience of Transbronchial Lung Cryobiopsy for Diagnosing Interstitial Lung Disease With a 2-Scope Technique

Background:

Transbronchial lung cryobiopsy (TBLC) has been used to establish the diagnosis of interstitial lung disease (ILD) in recent years. The technique and diagnostic yield vary among institutions. We report a new 2-scope technique and the results of TBLC in our institution.

Methods:

This is a retrospective chart review of patients who underwent TBLC for evaluation of ILD. Bronchoscopy with TBLC was performed by a board-certified interventional pulmonologist with a 2-scope technique under general anesthesia.

Results:

A total of 74 patients underwent TBLC with a 2-scope technique. Their mean age was 54±14 years. The mean tissue surface area was 63.54±6.76 mm². The average anesthesia time was 80.66 minutes. The diagnostic yield was 87.84%. The most common diagnosis was sarcoidosis pneumothorax, which occurred in 5 cases (7%). There was 1 case with bronchoscopic-related respiratory failure associated with significant bleeding. Death occurred in 3 cases (4%), which is comparable to recent mortality data for “elective” surgical lung biopsy for ILD (1.7% to 4.2%).

Conclusion:

TBLC with a 2-scope technique could be an alternative method for diagnosing various types of ILD in patients unfit for surgical lung biopsy. Further prospective studies should clarify its role in the diagnostic armamentarium for undiagnosed ILDs.

A New Tool for Transbronchial Cryobiopsies in the Lung: An Experimental Feasibility ex vivo Study

BACKGROUND

Transbronchial cryobiopsy (TBCB) is a minimally invasive procedure to establish a diagnosis of interstitial lung disease though with the disadvantage that samples have to be extracted together with the bronchoscope.

OBJECTIVES

The aim of the present study was to evaluate the feasibility of a new cryoprobe with which biopsy samples can be obtained through the working channel of the flexible bronchoscope.

METHODS

The feasibility of obtaining transbronchial specimens with TBCB was tested and the technique was compared to transbronchial forceps biopsy (TBFB) in a prospectively randomized ex vivo animal study using a standard flexible bronchoscopy technique. The rate of successful biopsies and the duration of the sampling procedure were recorded for both methods. Size and quality of the biopsies were histologically evaluated and measured.

RESULTS

Biopsy samples could be obtained in 93.3% of TBCB and in 79.0% of TBFB procedures (p = 0.182). Sampling procedure time did not differ in any clinically relevant manner between the two methods. The mean specimen area of TBCB samples was significantly higher compared to that of TBFB samples (8.08 ± 5.80 vs. 2.61 ± 2.14 mm2; p < 0.0001). TBCB specimens showed less artifacts and a significantly higher percentage of alveolar tissue (53.57 vs. 25.42%; p = 0.0285) than TBFB specimens.

CONCLUSIONS

It is feasible to retrieve TBCB samples of good quality and size with the new mini cryoprobe through the working channel of the bronchoscope, while the bronchoscope remains within the central airways throughout the whole procedure. Further studies are necessary to evaluate the safety and efficacy in an in vivo setting.

State of the art in the diagnosis and management of interstitial lung disease

The interstitial lung diseases (ILDs) are a diverse group of disorders characterized by a varying combination of inflammation and fibrosis of the pulmonary parenchyma. Treatment and prognosis of ILD typically depend on the underlying ILD subtype, highlighting the importance of accurate classification and diagnosis. Besides a thorough history and clinical examination, the protocol should include a 6-minute walk test, chest radiography, high-resolution computed tomography, biochemical analysis, pulmonary function tests, blood gas analysis, bronchoalveolar lavage, and, when necessary, a lung biopsy. The final diagnosis of ILD entities requires dynamic interaction between clinicians, radiologists and pathologists to reach a clinico-radiologic-pathologic diagnosis, the gold standard no longer being the histology but rather a multidisciplinary approach.