ABSTRACT

Numerous cases of gentamicin underdosing have been described in the literature in the context of sepsis and septic shock in anaesthesia-intensive care units (ICU). A survey of clinical practice was conducted with the aim to rationalise the use of gentamicin in the unit. The secondary objective was to propose a corrective formula for adjusting individual dosage.

A single-centre survey was used to determine the initial dose of gentamicin administered, in an anaesthesia-ICU, during the first hours of sepsis/septic shock. An initial retrospective phase allowed focusing on the points of improvement in terms of prescription. A second prospective phase enabled the evaluation of benefits following the implemented changes.

Fifty-one patients were included during the retrospective phase (2014-2015) and 28 patients during the prospective phase (2016-2017). Out-of-guideline prescriptions significantly decreased between these two study periods (i.e., pulmonary infections decreased from 70.5% to 18%, p<0.001) and the mean±standard deviation administered dosage increased from 7.3±1.2 mg kg−1 to 9.5±1.5 mg kg−1 (p<0.001). Nevertheless, the proportion of Cmax (peak plasma concentration) ≥30 mg L-1 and the mean Cmax did not change significantly. A significant association (p<0.05) was found between Cmax, body mass index, haematocrit and creatinine, enabling a corrective formula to be proposed.

The present study allowed improvement in gentamicin prescription in an anaesthesia-ICU. A Cmax ≥30 mg L−1 remains difficult to achieve, but a Cmax ≥16 mg L−1 could be considered relevant for community infections and would be more attainable. A corrective formula could be used to adjust the dosage.

Keywords: Corrective formula, gentamicin, intensive care unit, peak plasma concentration (Cmax), sepsis