Applying pharmacokinetic/pharmacodynamic principles for optimizing antimicrobial therapy during continuous renal replacement therapy

Continuous renal replacement therapy (CRRT) is progressively supplanting intermittent haemodialysis (IHD) in critically ill patients. Although CRRT indeed offers more appropriate haemodynamic, fluid, and metabolic stability, concern is rising about its impact on concomitant drugs and, in particular, antimicrobial treatment. Antimicrobial dose recommendations have been elaborated to avoid drug accumulation and toxicity in patients undergoing IHD. However, these dosing regimens have resulted in significant underdosing in patients undergoing CRRT, thereby increasing the risk of treatment failure and development of resistance. Applying pharmacokinetic/pharmacodynamic (PK/PD) principles may aid one to obtain more adequate antimicrobial therapy during CRRT. Much progress has been made in recent years resulting in relevant changes in particular antimicrobial therapies. In this review, we discuss antimicrobials that are frequently used in an intensive care setting. Drugs are divided according to their PK/PD characteristics and, wherever possible, dose recommendations during CRRT are provided. Of course, while therapeutic drug monitoring remains the best way to cope with PK/PD variability within a critically ill CRRT population, its bedside use is actually limited to some specific antibiotics.