Abstract
Purpose
To describe the pharmacokinetics of vancomycin in patients with continuous-flow left ventricular assist devices (CF-LVADs).
Methods
Eligible patients were ≥18 years old, implanted with a Heart Mate II CF-LVAD during January 2008-April 2012, and treated with vancomycin ≥48 hours for infection. Key exclusion criteria were unstable renal function, acute heart failure exacerbation, hemodynamic instability, and recent surgery. First-order elimination rate constant (Ke) and volume of distribution (Vd) were estimated using ideal (IBW), adjusted (AdjBW), actual (ABW), and fixed body weights. Estimated parameters were compared with measured pharmacokinetic parameters, which were calculated from steady state peak and trough vancomycin levels using one-compartment model equations.
Results
Twelve patients were included (age 44.9 ± 15 years, 91.7% male, 58.3% obese, CLcr 79.2 ± 27 mL · min-1). Common treatment indications were health-care associated pneumonia (41.7%), driveline infection (25%), and sepsis (16.7%). All methods of predicting Ke provided overestimates (p<0.05), ranging from 47 to 79%, depending on body habitus. Methods of predicting Vd using ABW in obese patients yielded overestimates of 74.5% (p<0.05), where IBW predictive Vd equations provided accurate assessments regardless of body habitus.
Conclusions
General population methods may not accurately estimate the pharmacokinetic parameters of vancomycin for compensated heart failure patients implanted with CF-LVADs.
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