Bioelectrical Impedance Analysis as a Bedside Tool to Estimate Volume of Distribution of Hydrophilic Antimicrobials in Critically Ill Patients

Abstract Background: Recent data suggest that antimicrobial pharmacokinetics (PK) like volume of distribution (Vd) or drug clearance (CL) is extremely altered in critically ill patients with sepsis or septic shock due to pathophysiological alterations (e.g. influence on fluid status). Bioelectrical impedance analysis (BIA) was recently introduced as a simple, non-invasive, bedside technique to assess hydration status. The primary aim of the present study was to explore the correlation between BIA parameters and Vd of hydrophilic antimicrobial agents in critically ill patients. Furthermore, the relationship between BIA measurements and clinical observations was evaluated.

Methods: We performed a validation study in healthy volunteers in September 2015 that confirmed the reproducibility of BIA. Subsequently, a prospective observational study was carried out in eligible patients treat-ed with amoxicillin/clavulanic acid, meropenem, piperacillin/tazobactam or vancomycin, admitted at the in-tensive care unit (ICU) of the University Hospitals Leuven from October 2015 to March 2016. BIA measurement was performed on the same day as the collection of blood samples to calculate PK parameters of the administered antibiotic.

Inclusion criteria

• Admitted to ICU ward
• Treated with one of the four studied antimicrobials

Exclusion criteria

• <18 years
• Pregnant
• Do Not Resuscitate code 2 or 3
• Renal replacement therapy
• ECMO
• Pacemaker/defibrillator
• Extended burns or dermatological ilness