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Article |

Does Intraoperative Blood Loss Affect Antibiotic Serum and Tissue Concentrations?

Sandra M. Swoboda, RN, MSN; Cindy Merz, MT; John Kostuik, MD; Brian Trentler; Pamela A. Lipsett, MD
Arch Surg. 1996;131(11):1165-1172. doi:10.1001/archsurg.1996.01430230047009.
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Objective:  To determine the effect of intraoperative blood loss on prophylactic cefazolin and gentamicin serum and tissue concentrations.

Design:  A prospective study of elective spinal instrumentation surgical procedures with an expected large blood loss.

Setting:  Tertiary care, inner-city university hospital.

Patients:  Eleven adult patients who underwent an elective surgical procedure that involved spinal instrumentation.

Intervention:  Standard perioperative administration of a combination of cefazolin and gentamicin. Serum and tissue samples were obtained consecutively throughout the surgical procedure.

Main Outcome Measures:  The effect of intraoperative blood loss on serum and tissue cefazolin and gentamicin concentrations and their pharmacokinetics.

Results:  At the time of the incision, serum cefazolin concentrations were greater than tissue concentrations (P=.07). A mean dose of 1.8-mg/kg gentamicin yielded low or nontherapeutic serum and tissue gentamicin concentrations. Cefazolin and gentamicin were eliminated from the tissue compartment slower than from the serum compartment (P<.03), while the half-life of cefazolin was significantly (P=.06) longer in the tissue compartment. The volume of distribution of cefazolin was normal (ie, 12.5 L), while the volume of distribution of gentamicin was 5-fold greater than expected. At 60 minutes after the incision, blood loss correlated with cefazolin tissue concentrations (r=−0.66, P=.05). Blood loss correlated with the change in tissue antibiotic concentrations for cefazolin (r=0.73, P=.04). In addition, the clearance of gentamicin from the tissues correlated with blood loss (r=0.82, P=.01).

Conclusions:  Based on measured pharmacokinetic values, additional doses of cefazolin should be administered when the operation exceeds 3 hours and blood loss is greater than 1500 mL. Doses of gentamicin greater than 1.8 mg/kg should be administered more than 30 minutes prior to the surgical incision.Arch Surg. 1996;131:1165-1172


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