The influence of controlled mechanical ventilation (CMV) on the pharmacokinetic profile of gentamicin has been examined in 23 patients after elective open heart surgery. A parallel design was adopted in two groups of patients: 13 patients requiring CMV for at least 32 h after surgery, all of whom were able to breath spontaneously (SB) after 72 h (study group), and 10 patients who required CMV for only a brief period and who showed SB at 32 h postsurgery. Haemodynamic parameters remained stable throughout the study. Apparent volume of distribution (V z ), half-life (t 1/2 ), total clearance (CL), peak (C maxss ) and trough (C minss ) plasma levels at steady-state for target levels (6-8 μg/ml), were measured. In the study group significant differences between CMV and SB conditions were found in V z (mean 0.36 and 0.25 l/kg), t 1/2 (mean 3.63 and 2.90 h) and C maxss (mean 4.30 and 5.53 μg/ml) while C minss (mean 1.06 μg·ml -1 and 0.92 μg·ml -1 ) did not change significantly. In contrast, the pharmacokinetics in the control group showed no differences. It appears that CMV leads to an increase in gentamicin V z , which accounts for the fall in C maxss below the therapeutic dose range (<5 μg/ml) recommended for gentamicin. It seems advisable to use a larger dose of gentamicin in patients receiving CMV, even before the level is assessed. © 1991 Springer-Verlag.
- mechanical ventilation
- therapeutic dose range