In order to optimize anti-cytomegalovirus (CMV) treatment with ganciclovir (GCV), in patients with multi organ failure treated with continuous renal replacement therapy (RRT), more information about ganciclovir pharmacokinetics in this setting is needed.

The primary objective is to describe the pharmacokinetics of ganciclovir in critically ill patients with acute renal failure treated with continuous renal replacement therapy, with a special emphasis on the extra-renal clearance and distribution volume.

Secondary objectives are to investigate if any co-factors, such as serum creatinine, weight, general hydration status, rest function of the native kidneys, etc. can help to describe the pharmacokinetics of GCV in these patients on continuous RRT as well as the relative influence of filtrations and dialysis on GCV elimination during different modalities of the treatment.

Inclusion Criteria:

• Patients in need of continuous RRT and GCV treatment
• 18 years of age or older.

Exclusion Criteria:

• Concomitant treatment with acyclovir or valacyclovir.
• Patient does not give informed consent.