Case Series of Continuously-infused Amphotericin-B and Follow-up Voriconazole Therapy for Severe Blastomycosis Pulmonary Infections

To evaluate six intensively studied patients admitted to medical intensive care with pulmonary blastomycosis requiring mechanical ventilation. Interventionally, all patients will receive continuously infused amphotericin-B (1 mg/kg/d); and then stepped down to oral or i.v. voriconazole once clinically responding. Blood will be sampled for amphotericin-B concentrations for the 3 first days (i.e. one blood sample per day); and when eventually changed over to voriconazole (i.e. generally after a total dose of 1 g has been reached of Amphotericin-B; as per usual practice). Once switched to oral or intravenous voriconazole, at the treating physicians discretion, then blood would once again be sampled for the next 3 days for voriconazole concentrations. MIC's of the infecting blastomyces would also be analyzed. The fungal isolate would be sent off to the Fungus Testing Laboratory at the University of Texas in San Antonio for susceptibility testing.

Clinical response to therapy relative to their initial pharmacokinetic and pharmacodynamic indices for amphotericin-B (i.e. daily free maximal concentration divided by the MIC) would be assessed in these 6 intensively studied patients. Clinical parameters assessed would be 1). time to fever defervescence; 2). time to white cell count resolution, and 3). improvements in respiratory gas exchange (i.e. specifically the rate of rise of the pressure of arterial oxygen (Pa02) divided by the fraction of inspired oxygen (Fi02) delivered through the ventilator (or PF ratio).