The population continues to increase in weight. Currently there are no guidelines in the dosing of cefazolin for the obese population. Standard dosing of cefazolin 2 grams for patients \<120 kg and 3 grams for patients \>120 kg is used as the dose for surgical prophylaxis. This makes no provisions for weight based dosing. There has been some recent data which states this might not be enough for the obese patients. The primary objective of this study is to determine if weight based dosing (30 mg/kg) of cefazolin as surgical prophylaxis for patients undergoing elective gastric bypass/laparoscopic Roux-en-y gastric bypass provides appropriate serum concentrations for a larger percentage of time than the current method of giving the standard 2 or 3 gram doses of cefazolin peri-operatively. The concentration of cefazolin in tissue will also be measured to help assess this question.
The hypothesis of this study is that customary doses of antibiotics, when administered for perioperative surgical prophylaxis, are insufficient to achieve adequate antibiotic concentrations in blood and tissues of morbidly obese patients (defined as a BMI greater than 40 kg/m2) and that these patients are therefore placed at high risk of surgical wound infections and poor clinical outcomes. Cefazolin is a first-generation cephalosporin commonly used for perioperative surgical prophylaxis in colorectal, abdominal, bariatric, gynecologic and obstetric, or orthopedic total joint arthroplasty surgical procedures. Previous cefazolin pharmacokinetic (PK) analysis in obese patients led to conflicting results and recommendations. It is not clearly know to what extent the pharmacokinetics of cefazolin in morbidly obese patients differ from those of non-obese patients. Specific dosing guidelines are then lacking. The main objective of this study is to assess the pharmacokinetics of cefazolin in morbidly obese after administrations of a standard recommended 2-3 g dose or a weight-base 30-mg/kg dose
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
NONE
The standard dose of Cefazolin will be administered intravenously.
The weight-based dose group will receive 30 mg/kg cefazolin dose intravenously.
University of Colorado Hospital
Aurora, Colorado, United States
Assessment of the Pharmacokinetics of Cefazolin in the Morbidly Obese
Since the goal of perioperative antimicrobial prophylaxis is to achieve free (unbound) serum and tissue drug levels that exceed the MIC for likely pathogens across the duration of the surgical procedure, and since redosing of cefazolin is recommended every 3-4 hours, PK/PD performance of cefazolin over that time frame will be analyzed. For the purposes of this study, pharmacodynamic targets are defined as fT\>MIC (time during which free drug concentrations exceed pathogen MICs) of 100% over periods of up to 4 hours in duration. The PK/PD probability of target attainment (PTA) for pharmacodynamic goals and the cumulative fraction of response (CFR) for both cefazolin regimens will be compared. A PTA of ≥90% and a CFR of ≥ 90% for a dosage regimen (i.e., predicted to meet pharmacodynamic targets in ≥ 90% of the total bacterial population across the full range of MICs) are considered optimum.
Time frame: Before cefazolin admin., then at 10, 30, 60, 120, 180 minutes after injection and at wound closure.
Incidence of surgical site infection
The incidence of surgical site infection will be monitored and compared.
Time frame: Within 1 month postoperatively
Hospital length of stay
The length of time the subject is hospitalized will be monitored and compared.
Time frame: Hospital discharge
Hospital readmission
Hospital readmission within 1 month postoperatively.
Time frame: Witihn 1 month after hospital discharge
Incidence of adverse outcomes
Adverse outcomes in these patients will be monitored and compared.
Time frame: Within 1 month postoperatively
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