title: Plasma cefazolin levels during cardiovascular surgery: effects of cardiopulmonary bypass and profound hypothermic circulatory arrest.
abstract: OBJECTIVE
  We sought to assess the effects of cardiopulmonary bypass and profound hypothermic circulatory arrest on plasma cefazolin levels administered for antimicrobial prophylaxis in cardiovascular surgery.
  
  
  METHODS
  Four groups (10 patients per group) were prospectively studied: vascular surgery without cardiopulmonary bypass (group A), cardiac surgery with a cardiopulmonary bypass time of less than 120 minutes (group B), cardiac surgery with a cardiopulmonary bypass time of greater than 120 minutes (group C), and cardiac surgery with cardiopulmonary bypass and profound hypothermic circulatory arrest (group D). Subjects received cefazolin at induction and a second dose before wound closure. Arterial blood samples were obtained preceding cefazolin administration, at skin incision, hourly during the operation, and before redosing. Cefazolin plasma concentrations were determined by using a radial diffusion assay, with Staphylococcus aureus as the indicator microorganism. Cefazolin plasma concentrations were considered noninhibitory at 8 microg/mL or less, intermediate at 16 mug/mL, and inhibitory at 32 microg/mL or greater.
  
  
  RESULTS
  In group A cefazolin plasma concentrations remained greater than 16 microg/mL during the complete surgical procedure. In group B cefazolin plasma concentrations diminished to 16 microg/mL or less in 30% of the patients but remained greater than 8 microg/mL. In group C cefazolin plasma concentrations decreased to less than 16 microg/mL in 60% of patients and were less than 8 microg/mL in 50% of patients. In group D cefazolin plasma concentrations reached 16 microg/mL in 66% of the patients but decreased to 8 microg/mL in only 1 patient.
  
  
  CONCLUSIONS
  For patients undergoing cardiac surgery with a cardiopulmonary bypass time of greater than 120 minutes, a single dose of cefazolin before skin incision with redosing at wound closure does not provide targeted antimicrobial cefazolin plasma levels during the entire surgical procedure. Patients undergoing profound hypothermic circulatory arrest are better protected, but the described protocol of prophylaxis is not optimal.
authors.affiliation: Department of Cardiothoracic Surgery, Stanford University, Stanford, Calif, USA. acaffare@stanford.edu
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Caffarelli
authors.forename: Jeff P
authors.initials: JP
authors.lastname: Holden
authors.forename: Ellen Jo
authors.initials: EJ
authors.lastname: Baron
authors.forename: Harry J M
authors.initials: HJ
authors.lastname: Lemmens
authors.forename: Holly
authors.initials: H
authors.lastname: D'Souza
authors.forename: Vincent
authors.initials: V
authors.lastname: Yau
authors.forename: Cornelius
authors.initials: C
authors.lastname: Olcott
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Reitz
authors.forename: D Craig
authors.initials: DC
authors.lastname: Miller
authors.forename: Pieter J A
authors.initials: PJ
authors.lastname: van der Starre
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000097:blood*; D019072:Antibiotic Prophylaxis; D002315:Cardiopulmonary Bypass; D002437:Cefazolin / Q000097:blood*; D050792:Circulatory Arrest, Deep Hypothermia Induced; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D000900:Anti-Bacterial Agents; D002437:Cefazolin