MRCP2-4449
A 57-year-old man presents to the Emergency Department with a two-week history of increasing shortness of breath and frank haemoptysis for the past few days. He had recently returned from a trip to Turkey. On admission, he was short of breath at rest and unable to complete full sentences. He also reported increasing orthopnoea for the past few weeks. He had a medical history of diabetes, hypertension, hypercholesterolaemia, and gout, as well as a long history of recurrent epistaxis, rhinitis, and sinusitis. He was taking several medications, including mometasone nasal spray, allopurinol, ramipril, amlodipine, simvastatin, metformin, and gliclazide. He smoked 20 cigarettes per day and did not drink alcohol.
Upon examination, he appeared very unwell and was in obvious respiratory distress. His respiratory rate was 28/min, his oxygen saturations were 90% on air, his blood pressure was 108/72 mmHg, his heart rate was 129, and his temperature was 37.9 degrees Celsius. His cardiovascular system had normal heart sounds with a JVP of 3cm, while his respiratory system showed the use of accessory muscles with bibasal fine crackles. Examination of the gastrointestinal and neurological systems was unremarkable.
Initial investigations revealed low Hb, high platelets and WBC, high ESR, low Na+, high K+, high urea, high creatinine, high CRP, and normal glucose. Chest x-ray showed bilateral patchy infiltration, while ECG showed normal sinus rhythm. Urinalysis showed blood and protein, but negative leuc/nit and glucose. ABG on 15 l/min oxygen showed high PaO2, low PaCO2, low HCO3, and high pH.
Further investigations revealed nil growth in urine MCS and blood culture, normal systolic function and valvular appearances, and no vegetations seen in transoesophageal echocardiogram. C3 and C4 were abnormal, ANA and dsDNA were negative, cANCA was positive, pANCA was negative, and rheumatoid factor was negative.
Given the likely underlying diagnosis, what is the best next step while awaiting haemodialysis?