Lung Ultrasound – A Novel Diagnostic Tool To Phenotype Chronic Lung Allograft Dysfunction?

Introduction

Lung transplantation (LTx) is a well-established treatment in a number of end-stage lung diseases that increases quality of life and survival corresponding to a one-, five-, and ten-year survival rate of 90%, 60–70%, and 40–50%, respectively. Most patients die of chronic lung allograft dysfunction (CLAD) which affects approximately 50% of all lung transplant recipients after five years. Since 2010 growing attention has been paid to the phenotyping of CLAD as bronchiolitis obliterans syndrome (BOS) and restrictive CLAD (rCLAD). BOS is defined as a persistent decline in forced expiratory volume in one second (FEV₁) of 20% compared to the average of the two best post-transplant values, whereas rCLAD is defined as a combined decline in FEV₁ and total lung capacity (TLC) of more than 10% compared to the best post-transplant baseline values (Sato M et al. J Heart Lung Transplant. 2011;30:735-42). BOS may respond well to pharmacological treatment, whereas there is not yet any documented rCLAD treatment. Also, in contrast to BOS, rCLAD is associated with pleuroparenchymal fibroelastosis (PPFE) on high-resolution computed tomography (HRCT) and has an inferior survival rate compared to BOS (Verleden SE et al. J Heart Lung Transplant. 2014;33:270-7).

Identification of pleura pathology and fibrosis in interstitial lung diseases, such as idiopathic PPFE, can be identified using lung ultrasound (LUS) in the presence of pleural thickening and the so-called interstitial syndrome (IS), which, in accordance with the international evidence-based guideline for point-of-care LUS, is defined as more than 3 B-lines in more than 2 anterior and/or lateral zones on each hemithorax (Volpicelli G et al. Intensive Care Med. 2012;38:577-91). As a radiation-free and fast procedure which is easily performed with minimal discomfort for the patient, LUS excels in a clinical setting.

Below we describe LUS findings in a lung transplant recipient compatible with PPFE findings on an HRCT, which in combination with lung physiology was in favor of rCLAD.