Anaesthetic technique does not influence surgical site infections - smoking and obesity do
ESRA Academy. Van Zundert A. Mar 7, 2017; 170346
André Van Zundert
André Van Zundert
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Kopp et al estimated that in 2030, some four million patients will undergo TKA and THA on an annual basis in the USA, excluding a fast growing number of revision procedures. Patients undergoing total joint arthroplasty are prone to systemic infection including sepsis urinary tract infection and pneumonia. The cost of surgical site infection (SSI) and peri-prosthetic joint infection (PJI) is projected to triple ($1.62 billion) by 2020.
Conflicting results have been published about whether or not regional anaesthesia (epidural/spinal) helps in reducing the incidence of SSI in patients undergoing major arthroplasty surgery. The literature provides a list of risk factors which are most predictive of PJI and include: a) SSI; b) concurrent malignancy; c) revision procedure; d) a higher nosocomial infection surveillance score (> 2); e) co-morbidity (diabetes mellitus, obesity, rheumatoid arthritis, steroid therapy); and f) general anaesthesia.
Kopp et al performed a 10-year retrospective, single-centre case-controlled study, comparing the risk of SSI within a year of surgery (primary and revision TKA and THA) and identified 202 patients with SSIs (57% within the first month of procedure; 43% between months 1–12) and 404 controls. Each case was matched with two controls based on type or procedure, sex, joint site, surgical duration and ASA physical status. Details of anaesthetic management (type of anaesthesia, i.e. general or neuraxial block; postoperative pain relief method, i.e. peripheral nerve block, epidural analgesia or PCA; perioperative temperatures; antibiotic coverage), surgical management (type of surgery, i.e. primary and revision TKA/THA; unilateral or bilateral arthroplasty; urgency of surgery; total duration of tourniquet time and surgical time) and of the postoperative period (use of anticoagulants; presence of SSI, i.e. superficial, deep, or organ space; and microbiology) were recorded. The case-controlled study could not find a link between the type of primary anaesthetic and the incidence of SSI in patients undergoing major lower extremity joint arthroplasty, but demonstrated a clear relationship of SSI in patients who were active smokers and obese.
Far too often regional anaesthesia, as opposed to general anaesthesia, is given competencies such as a reduction in cancer recurrence in patients undergoing tumour surgery and – as in this case – as a means of reducing overall systemic infection. Both general and regional anaesthesia are safe methods to be used during and after surgery. The mechanisms by which regional anaesthesia may decrease the risk of systemic infections may include a variety of factors. It is known that surgery and pain decrease peripheral perfusion through vasoconstriction. By adequately blocking the autonomic response, neuraxial and peripheral nerve blockade may increase vasodilatation and reduce the inflammatory response, allowing the immune system to focus better on elimination of bacteria. Indeed, general anaesthesia using volatile anaesthetics and opioids impairs immune function of neutrophils, macrophages, dendritic cells, T-cells and natural kill cells. Factors, other than anaesthesia, are probably much more contributory to the development of infections, such as active smoking and obesity, which are known to result in a pro-inflammatory response affecting the postoperative immune response, impairing wound healing by decreasing tissue oxygenation, reducing inflammatory cell responsiveness and oxidative bacterial mechanisms. These patients would benefit by smoking cessation (which would lead to restoration of tissue oxygenation and inflammatory cell response within 4 weeks) and reducing weight. Nevertheless, regional anaesthesia has much more to offer than just a reduction in infection prevalence. Anaesthetists have to keep an eye on the total picture, of which the anaesthetic technique is only one aspect.


Surgical site infection (SSI) is one of the most challenging and costly complications associated with total joint arthroplasty. Our primary aim in this 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. Our secondary aim was to determine which patient, anesthetic, and surgical variables influence the risk of SSI. We hypothesized that patients who undergo neuraxial anesthesia may have a lesser risk of SSI compared with those who had a general anesthetic.


We 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).


During the 11-year period, 202 SSIs were identified. 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, no significant association was found 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 also was 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/m compared with those with BMI < 25 kg/m).


Recent studies using large databases have concluded that the use of neuraxial compared with general anesthesia is associated with a decreased incidence of SSI in patients undergoing total joint arthroplasty. In this retrospective, case-controlled study, we found no difference in the incidence of SSI in patients undergoing total joint arthroplasty under general versus neuraxial anesthesia. We also concluded that the use of peripheral nerve blocks does not influence the incidence of SSI. Increasing BMI and current smoking were found to significantly increase the incidence of SSI in patients undergoing lower extremity total joint arthroplasty.

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