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CHRONIC LUNG ALLOGENIC DYSFUNCTION: A TRAPPED LUNG SAVED BY THE TUBE

      TOPIC: Transplantation
      TYPE: Medical Student/Resident Case Reports
      INTRODUCTION: Transplant rejection is a commonly encountered complication of solid organs with highest incidence seen after lung transplant. Repeated episodes of rejection leads development of Chronic Lung Allograft Dysfunction (CLAD) that can be phenotypically sub-classified as Bronchiolitis Obliterans Syndrome(BOS), Restrictive allograft syndrome (RAS) or mixed based on spirometry and Total Lung Capacity.
      CASE PRESENTATION: We present a 34 year old female with history of cystic fibrosis F508/N1303, status post bilateral lung transplant, complicated by multiple previous rejections leading to CLAD-RAS, Cytomegalovirus mismatch, and previous colonization with Achromobacter, Aspergillus fumigatus presented with acute onset of dyspnea with accompanying fever. Further workup was significant for new bilateral lower lobe infiltrates in the context of previously known right upper lobe pleuroparenchymal fibrosis, lymphopenia, and negative COVID-19 x3 testing.Patient presented with acute hypoxic respiratory failure treated with high flow nasal cannula. Initial bronchoscopy with BAL demonstrated neutrophilic predominance prompting initiation of broad-spectrum antimicrobial therapy given previous patient's history. Further respiratory decline prompted intubation on hospital day 4 and initiation of high dose steroids. Infectious work up including multiple BAL cultures remain largely negative.The course was further complicated with development new right-sided pneumothorax and small apical predominant hydropneumothorax on the left seen on CT thorax leading to persistent hypercarbia, PCO2 78-115 mm Hg and high minute ventilation. The barotrauma, in the context of known upper lobe fibrotic disease, while being on ventilator support. Image guided right thoracostomy tube placement was pursued leading to normalization of hypercarbia, with increase in tidal volumes and mild expansion of right lung indicating improved dead space. Sedation was weaned and the patient was successfully extubated to room air.
      DISCUSSION: Acute transplant rejection remains one of the highest complications experienced by post-lung transplant patients. As our case demonstrates, it is critical to manage patients with CLAD who present with acute hypoxemic respiratory failure at a multidisciplinary center with early diagnostic work up to rule out reversible etiology such as infectious processes especially in the COVID-19 pandemic era . Previous studies have shown that acute cellular rejection (ACR) is a known risk factor for development of CLAD-RAS phenotype.
      CONCLUSIONS: As seen with our patient; ACR superimposed on CLAD-RAS leading to lung trapping and propensity for barotrauma, increasing the dead space ventilation. Prompt steroid therapy to reduce the inflammatory process, and image guided interventions can assist in reducing the deadspace and improve the compliance of the transplant lung.
      REFERENCE #1: Verleden, Geert M., et al. "Chronic Lung Allograft Dysfunction: Definition, Diagnostic Criteria, and Approaches to Treatment?A Consensus Report from the Pulmonary Council of the ISHLT." The Journal of Heart and Lung Transplantation, vol. 38, no. 5, 2019, pp. 493–503., doi:10.1016/j.healun.2019.03.009.
      REFERENCE #2: Glanville, Allan R., et al. "Chronic Lung Allograft Dysfunction: Definition and Update of Restrictive Allograft Syndrome?A Consensus Report from the Pulmonary Council of the ISHLT." The Journal of Heart and Lung Transplantation, vol. 38, no. 5, 2019, pp. 483–492., doi:10.1016/j.healun.2019.03.008.
      DISCLOSURES: No relevant relationships by Jay Patel, source=Web Response