Intraoperative positive fluid balance improves tissue diffusion of ceftizoxime

AIM OF STUDY: To demonstrate that administration of fluids and the consequent improvement of fluid balance during a surgical procedure can modify the tissue diffusion of ceftizoxime. METHODS: Twenty-eight patients (30-79 years) undergoing major abdominal surgery of the colon were administered ceftizoxime 30 mg/kg i.v. at induction of anesthesia. A sample of arterial blood was taken before administration of the drug (t0) and then again at the time of vascular occlusion of the colon segment to be removed (t1). A sample of the segment of removed colon was taken. The patients were divided into two groups on the basis of the fluid balance between t0 and t1: group A (n = 17) with a fluid balance <1,000 ml and group B (n = 11) with a fluid balance >1,000 ml. The parameters evaluated in each group were: weight, height and age of the patients, serum and tissue antibiotic concentration, percent ratio of serum and tissue concentration, time elapsed between t0 and t1, volume of administered fluids between t0 and t1, diuresis and hourly diuresis between t0 and t1 and body fluid distribution, obtained using a bioelectrical impedance analyzer. The mean results obtained in the two groups were then compared using Student's t test. RESULTS: The balance of fluids calculated up to t1 was 675 +/- 308 ml for group A and 1,411 +/- 405 ml for group B (p < 0.01). The means of the recorded values that showed statistically significant differences were: mean percent concentration ratio (43.6 +/- 8.4 vs. 84 +/- 16%; p < 0.05), concentration in the colonic segment (16.3 +/- 7.9 vs. 37.2 +/- 25.9 mg/ml; p < 0.05), urinary volume gathered up to t1 (538 +/- 557 vs. 169 +/- 104 ml; p < 0.05), hourly urinary volume up to t1 (311.1 +/- 296 vs. 97.6 +/- 77.9 ml/h; p < 0.05), percent variation of resistance (95.1 +/- 5.1 vs. 89.7 +/- 8.6; p < 0.05). The other means did not show any significant statistical differences. CONCLUSIONS: A higher tissue water level seems to facilitate the penetration of the antibiotic into the tissue according to the pharmacokinetic characteristics of ceftizoxime: high amount of free drug (not bound to plasma proteins) and high hydrosolubility.