The use of iohexol as a marker to measure glomerular filtration rate in the non-steady state of patients undergoing robot-assisted colorectal surgery

Abstract

Introduction Perioperative acute kidney injury (AKI) is associated with increased morbidity and mortality. Estimated glomerular filtration rate (eGFR) is routinely used to monitor renal function. This is an imprecise tool in the non-steady state condition and much kidney function can be lost before it is detectable by the eGFR method. A continuous low-dose infusion of iohexol has been proposed as a potentially valuable method of measuring GFR (mGFR). This novel method was tested in patients undergoing major abdominal cancer surgery. The aim for this thesis was to evaluate the feasibility of using iohexol to measure GFR, and to present data from a clinical feasibility study where the exogenous substance iohexol was applied for measurement of GFR.

Methods Clinical observational study of a preoperative single iohexol injection and a continuous low-dose infusion of iohexol for 72 hours in four patients undergoing robot-assisted colorectal cancer surgery. Plasma iohexol clearances were measured at timed intervals and compared to eGFR calculated from creatinine and cystatin C levels.

Results eGFRcystatin C demonstrated a different variability from that of mGFRiohexol, while eGFRcreatinine showed very little variation for the duration of the study. Furthermore, eGFRcreatinine and eGFRcystatin C underestimated actual measured GFR.

Conclusions Measurement of renal function in the perioperative setting is feasible with single injection and continuous low-dose infusion of iohexol. Iohexol plasma clearance should be applied when accurate GFR measurements are required.