Research

In vivo validation of the adequacy calculator for continuous renal replacement therapies

Zaccaria Ricci¹ , Gabriella Salvatori², Monica Bonello³, Tirak Pisitkun⁴, Irene Bolgan⁵, Giuseppe D'Amico⁶, Maurizio Dan⁷, Pasquale Piccinni⁷ and Claudio Ronco⁸

¹Consultant, Department of Intensive Care, Policlinico Umberto I, Rome, Italy

²Research fellow, Department of Nephrology, St Bortolo Hospital, Vicenza, Italy

³Specialist registrar, Department of Nephrology, St Bortolo Hospital, Vicenza, Italy

⁴Research fellow, Department of Nephrology, St Bortolo Hospital, Vicenza, Italy

⁵Statistician, Department of Nephrology, St Bortolo Hospital, Vicenza, Italy

⁶Research fellow, Department of Intensive Care, Policlinico Umberto I, Rome, Italy

⁷Head, Department of Intensive Care, St Bortolo Hospital, Vicenza, Italy

⁸Head, Department of Nephrology, St Bortolo Hospital, Vicenza, Italy

author email corresponding author email

Critical Care 2005, 9:R266-R273doi:10.1186/cc3517

Published:	7 April 2005

Abstract

Introduction

The study was conducted to validate in vivo the Adequacy Calculator, a Microsoft Excel-based program, designed to assess the prescription and delivery of renal replacement therapy in the critical care setting.

Methods

The design was a prospective cohort study, set in two intensive care units of teaching hospitals. The participants were 30 consecutive critically ill patients with acute renal failure treated with 106 continuous renal replacement therapies (CRRT). Urea clearance computation was performed with the Adequacy Calculator (K_CALC). Simultaneous blood and effluent urea samples were collected to measure the effectively delivered urea clearance (K_DEL) at the beginning of each treatment and, during 73 treatments, between the 18th and 24th treatment hour. The correlation between 179 computed and 179 measured clearances was assessed. Fractional clearances for urea were calculated as spKt/V (where sp represents single pool, K is clearance, t is time, and V is urea volume of distribution) obtained from software prescription and compared with the delivered spKt/V obtained from empirical data.

Results

We found that the value of clearance predicted by the calculator was strongly correlated with the value obtained from computation on blood and dialysate determination (r = 0.97) during the first 24 treatment hours, regardless of the renal replacement modality used. The delivered spKt/V (1.25) was less than prescribed (1.4) from the Adequacy Calculator by 10.7%, owing to therapy downtime.

Conclusion

The Adequacy Calculator is a simple tool for prescribing CRRT and for predicting the delivered dose. The calculator might be a helpful tool for standardizing therapy and for comparing disparate treatments, making it possible to perform large multi-centre studies on CRRT.