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Does intraoperative blood loss affect antibiotic serum and tissue concentrations?
S M Swoboda1, C Merz, J Kostuik
1Department of Surgery, Johns Hopkins University Schools of Medicine and Nursing, Baltimore, Md., USA.
Archives of Surgery (Chicago, Ill. : 1960)
|November 1, 1996
Summary
Intraoperative blood loss significantly impacts cefazolin and gentamicin levels during spinal surgery. Adjusting gentamicin dosing timing and considering additional cefazolin doses for prolonged procedures or substantial blood loss is recommended for effective prophylaxis.
Area of Science:
- Pharmacology
- Surgical Infection Prophylaxis
- Clinical Pharmacokinetics
Background:
- Prophylactic antibiotics like cefazolin and gentamicin are crucial in preventing surgical site infections.
- Intraoperative blood loss can potentially alter the pharmacokinetics and pharmacodynamics of these antibiotics.
- Optimizing antibiotic concentrations is essential for achieving therapeutic efficacy.
Purpose of the Study:
- To investigate the impact of intraoperative blood loss on serum and tissue concentrations of prophylactic cefazolin and gentamicin.
- To evaluate the pharmacokinetic changes of these antibiotics in relation to blood loss during spinal instrumentation procedures.
Main Methods:
- A prospective study involving 11 adult patients undergoing elective spinal instrumentation surgery with expected large blood loss.
- Standard perioperative administration of cefazolin and gentamicin.
- Consecutive collection of serum and tissue samples throughout the surgical procedure for concentration analysis.
Main Results:
- Gentamicin (1.8 mg/kg) resulted in low or non-therapeutic serum and tissue concentrations.
- Blood loss correlated with decreased cefazolin tissue concentrations and altered cefazolin and gentamicin tissue concentrations.
- Cefazolin and gentamicin exhibited slower elimination from tissue compared to serum, with longer half-lives in tissue.
Conclusions:
- Additional cefazolin doses are advised for operations exceeding 3 hours with blood loss >1500 mL.
- Gentamicin doses >1.8 mg/kg should be administered over 30 minutes before surgical incision to ensure adequate tissue concentrations.