Changes in urinary L-type fatty acid binding protein (L-FABP) during polymyxin B immobilized fiber column direct hemoperfusion (PMX-DHP) therapy for acute interstitial pneumonia: a case report

Abstract

A 79-year-old male visited the local clinic to consult about dyspnea, but was transferred to our hospital because of respiratory failure. On arrival, the patient had a consciousness level on the Japan Coma Scale (JCS) of 100, blood pressure 110/80mmHg, pulse rate 116/min, and SpO₂ 60% in room air. Blood tests showed a white blood cell (WBC) count of 23,200/μL, C-reactive protein (CRP) levels of 21.15 mg/dL, an estimated glomerular filtration (eGFR) rate of 124 mL/min/1.73m², and KL-6 levels of 666 U/mL. Chest computed tomography (CT) revealed extensive consolidation and ground-glass opacity in both lungs. The patient was diagnosed with acute interstitial pneumonia, and steroid therapy was started. However, polymyxin B immobilized fiber column direct hemoperfusion (PMX-DHP) therapy was performed for 6 hours on both the 4th and the 5th hospital day because of persistent respiratory failure. The PaO₂/FiO₂ (P/F) ratio improved from 67 to 165 on the 7th day, but respiratory failure progressed because of bilateral pneumothorax, and the patient died on the 20th day. No change in eGFR occurred during treatment. Before PMX-DHP, urinary L-type fatty acid binding protein (L-FABP) was 104.3 μg/g.Cre., declining to 40.8 μg/g.Cre. on the 7th day due to oxygenation improvement, and then rising again to 314.6 μg/g.Cre. on the 15th day with the progression of respiratory failure. Serum lactate levels exhibited the same behavior as urinary L-FABP. The authors propose that circulatory disorders induced by respiratory failure may lead to proximal tubule injury.