Serum creatinine levels during cardiac surgery: absence of effect by aminoglycosides

The literature indicates that the relative nephrotoxicities of the three drugs used in this investigation are gentamicin > tobramycin ≥ netilmicin. Serum creatinine levels over time were used in an attempt to elucidate the situation. They varied widely in all three groups and in controls in theatre. No definite trend was shown. Measurements performed for the ICU period showed continued variation. Fluctuations were so great during the perioperative period that the levels were analysed in terms of 44 μmol/litre difference between admission and discharge, ignoring changes between these times. It is now clear that the operative procedure itself is associated with fluctuating serum creatinine levels. The use of these aminoglycosides does not measureably affect the situation adversely over the short period of treatment. The use of nomograms, based on creatinine levels, to set aminoglycoside doses during the perioperative period may therefore be misleading, because of the wide fluctuations shown.