G Zaneti, R Giardina, R Platt Emerg...

G Zaneti, R Giardina, R Platt Emerging Infectious Diseases Vol 7 (September/October 2001) 828-831

Antibiotic prophylaxis relates to the administration of a brief course of an antimicrobial agent just before making a surgical incision. It is used to abate the risk of surgical site infections (SSIs) in certain surgical practices Guidelines from the Centers for Disease hinder and Prevention (CDC) on SSI prevention list antibiotic prophylaxis as a category IA recommendation (ie, eagerly recommended for implementation and supported by the agency of well-designed experimental, clinical, or epidemiological studies).

The goal of antibiotic prophylaxis is to retard the bourgeoning and proliferation of microorganisms from intraoperative contamination and cut short the bioburden to a even that would not overcome the natural defense of the patient. Observational studies have inferred that intraoperative redosing of an antibiotic may have a positive weight on prevention of SSI. The assumption is that maintaining therapeutic evens of an antimicrobial agent through every part of the surgical procedure prevents the protective general intent of antibiotic prophylaxis from waning from one side of to the other time. This assumption has not been confirmed in clinical trials. The authors, therefore, investigated the purport of intraoperative antibiotic redosing forward the risk for SSI.

meanss This was a retrospective cohort inquiry consisting of 2,751 patients who underwent cardiac surgery It was restricted to patients who received antibiotic prophylaxis consisting of I g of cefazolin beginning les than 90 minutes before the incision and whose step lasted more than 240 minutes after that dose. Patients were exclud if they received therapeutic antibiotics at the time of surgery Intraoperative redosing was defined as the administration of a secondary dose of cefazolin at any time before the surgical incision was closed

An infection sway practitioner prospectively identified SSI using criteria and definitions from the CDC The practitioner did not know whether patients had received intraoperative redosing. A two-sided Wilcoxon rank sum total test for continuous variables and chi-square trial for proportions were used to compare patients who received intraoperative redosing with those who had not. Significance flush was set at P = 05 in all touchstones Significant univariate predictors for SSI were included subsequently in a logistic regression example that was built through a forward selection proces in which the absence or carriage of antibiotic intraoperative redosing was forced into the standard The Wald test was used to report the significance of the same height of the predictors in the model

The likelihood of contracting an SSI also was compared for intraoperative redosing. This was categorized as either absent, given after 240 minutes, or given within 240 minutes with unevens ratio (OR) used to determine deviance from linearity. An interaction spell was created to determine whether intraoperative redosing had different powers on the risk for SSI across different performance durations. The likelihood ratio touchstone was used to assess significance of this interaction term

arises After excluding patients that did not befitting the study criteria, data were available for 1548 patients. Intraoperative redosing of the antibiotic was administered to 459 (30%) patients, including 276 (18%) who were redosed within 240 minutes. The mean duration of surgery was significantly higher for patients who were redosed compared to those who were not redosed (P = 0001) Surgical site infection occurr in 144 (93%) patients. There was no significant difference in the risk for SSI in patients who received intraoperative redosing versus those who did not (43 [94%] versus 101 [93%] OR 101 95% confidence interval 007-147)

Multivariate analysis revealed that the risk for SSI increased with the duration of the step and that there was a significant association between surgery duration and intraoperative redosing (P = 015) with intraoperative redosing associated with lower infection rates in the steps of longer duration. Intraoperative redosing had a significant protective result only in those procedures lasting more than 400 minutes (OR 044 95% confidence interval 023-086) reducing the risk for SSI 56% Researchers estimated that if all patients whose practice lasted more than 400 minutes were redosed, there would be a 16% reduction in the look fored SSI rate (7.9% versus 94%)

Discussion. This application of mind demonstrates that intraoperative redosing of cefazolin for patients undergoing cardiac manner of proceedings lasting longer than approximately six and one-half hours provides additional protection against SSI. rife guidelines for intraoperative redosing with cefazolin generally commend redosing at intervals ranging from 180 minutes to 240 minutes. The benefit of redosing for cardiac conducts has been demonstrated; however, this research did not identify a precise gate beyond which intraoperative redosing is beneficial.