No Link Found Between Infection and Type of Anesthesia

Is there a relationship between the type of anesthesia used to perform a joint replacement surgery and the incidence of surgical site infections (SSI)?

According to a new study titled “The Impact of Anesthetic Management on Surgical Site Infections in Patients Undergoing Total Knee or Total Hip Arthroplasty” published in the November 15, 2015 issue of the journal Anesthesia & Analgesia the answer is ‘no’. And its conclusion appears to debunk earlier research that purported to find a link between the type of anesthesia used in joint replacements and a risk of surgical site infection.

Surgical site infection is one of the most challenging and costly complications associated with total joint arthroplasty. The primary of the case-controlled trial was to compare the risk of SSI within a year of surgery for patients undergoing primary total knee arthroplasty (TKA) or total hip arthroplasty (THA) and revision TKA or THA under general anesthesia versus neuraxial anesthesia.

The researcher’s secondary aim was to determine which patient, anesthetic, and surgical variables influence the risk of SSI. The researchers hypothesized that patients who undergo neuraxial anesthesia may have a lesser risk of SSI compared with those who had a general anesthetic. The researchers were Sandra L. Kopp. M.D.; Elie F. Berbari, M.D.; Douglas R. Osmon, M.D., MPH; Darrell R. Schroeder, M.S.; James R. Hebl, M.D.; Terese T. Horlocker, M.D. and Arlen D. Hanssen, M.D.

The seven researchers conducted a retrospective, case-control study of patients undergoing primary or revision TKA and THA between January 1, 1998, and December 31, 2008, who subsequently were diagnosed with an SSI. The cases were matched 1:2 with controls based on type of joint replacement (TKA versus THA), type of procedure (primary, bilateral, revision), sex, date of surgery (within 1 year), ASA physical status (I and II versus III, IV, and V), and operative time (<3 vs >3 hours).

They found 202 SSIs during the 11-year study period. Of the infections identified, 115 (57%) occurred within the first 30 days and 87 (43%) occurred between 31 and 365 days. From both univariate and multivariable analyses, the authors found no significant association between the use of central neuraxial anesthesia and the postoperative infection (univariate odds ratio [OR] = 0.92; 95% confidence interval [CI], 0.63–1.34; P = 0.651; multivariable OR = 1.10; 95% CI, 0.72–1.69; P = 0.664).

The use of peripheral nerve block was also NOT found to influence the risk of postoperative infection (univariate OR = 1.41; 95% CI, 0.84–2.37; P = 0.193; multivariable OR = 1.35; 95% CI, 0.75–2.44; P = 0.312). The factors that were found to be associated with postoperative infection in multivariable analysis included current smoking (OR = 5.10; 95% CI, 2.30–11.33) and higher body mass index (BMI) (OR = 2.68; 95% CI, 1.42–5.06 for BMI ≥ 35 kg/m² compared with those with BMI < 25 kg/m²).

The authors concluded that there was no difference in the incidence of SSI in patients undergoing total joint arthroplasty under general versus neuraxial anesthesia. They further wrote that the use of peripheral nerve blocks does not influence the incidence of SSI. More meaningful to SSI risk was higher rate of BMI and smoking—both of which were found to significantly increase the incidence of SSI in patients undergoing lower extremity total joint arthroplasty.

The conclusions of this study are in contrast to other, recent studies using large databases which concluded that the use of neuraxial compared with general anesthesia was associated with a decreased incidence of SSI in patients undergoing total joint arthroplasty.