Infection and Anticoagulation Considerations in Pain Procedures

Definition of SSIs

Identification of SSI is based on physical examination findings of localized pain/tenderness, swelling, erythema, heat, or purulent drainage, cultures, and radiologic findings ( Fig. 74.1 ). Superficial SSIs involve the skin and subcutaneous tissues. Deep SSIs involve the fascia, muscle layers, and organ/space infections. Site infections occurring in the absence of an implantable device are defined as occurring within 30 days of the operation. When implantable devices are involved, the time is extended, and infections may occur within 12 months following a device implant.

Pathogens Associated With SSIs

Organisms that cause SSIs can be categorized as endogenous or exogenous sources. The most common pathogens are Staphylococcus aureus , Staphylococcus epidermidis, Streptococcus , Escherichia coli , and Pseudomonas aeruginosa . The most common source of infection is from the patient’s own flora. ^{, ,} It has been shown that pathogenic Staphylococcus aureus isolated from an infected wound matches cultures from the patient’s nares 80%–85% of the time.

Scope of Interventional Pain Procedures and Risk of Infection

Interventional pain procedures and surgeries vary considerably based on the pain syndrome being treated, surgical technique, and surgical theater environment. The invasiveness of procedures varies, and thus different infection control practices must be considered. Recommendations to prevent SSIs have been published by the CDC, NICE, and SCIP ( Tables 74.1 , 74.2 , and 74.3 ). ^{, , ,}

Patient Risk Factors

Physicians should recognize patient-related risk factors, including older age, poor nutritional status, diabetes mellitus, smoking, obesity, coexisting infection on a remote body site, colonization with Staphylococcus aureus , and altered immunity (e.g. immunosuppressive agents) prior to performing a procedure, and efforts should be made to correct any modifiable risk factors ( Table 74.4 ). Post-market surveillance data on SCS and IDDS implants revealed that 38% and 70% of patients with SCS and IDDS infections, respectively, have a medical comorbidity that increases the risk of infections. Smoking has been associated with an increased risk of SCS infections, likely secondary to the development of microvascular disease leading to tissue ischemia and poor wound healing, and worse pain scores and opioid consumption post-SCS implant. ^, Although the biologic effects of cancer and chemotherapeutic drugs can weaken host immunity, a retrospective study demonstrated that implantable pain therapies can still be utilized in cancer patients without significantly increasing the risk of SSI when appropriate infection control measures are taken.

A thorough history and physical examination should be performed preoperatively to identify patient risk factors prior to surgery. Many measures can be taken to reduce the risk of SSIs, such as glucose optimization, tobacco cessation (for at least four weeks), optimizing viral load in HIV patients, minimizing/avoiding perioperative steroids, and treating remote infections (e.g., urinary tract). Non-modifiable risk factors need to be documented, and a discussion with the patient regarding the associated increased risk of infection should occur prior to the pain intervention.

Staphylococcus Aureus Carriers

Staphylococcus aureus is the leading cause of SSIs, accounting for approximately 20% of all SSIs and 30% of ICD implant infection. More than 80% of nosocomial Staphylococcus aureus infections are endogenous, and the number of cases of methicillin-resistant S. aureus (MRSA) SSIs is increasing. ^, Staphylococcus aureus nasal colonization rates range from 20%–50%.

Methicillin-sensitive S. aureus (MSSA) and MRSA carriers have been shown to have a significantly higher risk of developing an SSI (two to nine times higher). Therefore identification of carriers followed by decolonization is critical in reducing SSI rates, and is cost effective. ^{, , ,} Prior to implantable pain therapies, patients can be screened for MSSA and MRSA. If positive, the patient can be decolonized, and preoperative antibiotic therapy is tailored based on the results.

Decolonization protocols involve the application of mupirocin 2% nasal ointment applied twice daily combined with chlorhexidine gluconate soap total-body washes daily for a duration of five days immediately preceding surgery. ^, Utilization of decolonization protocols in individuals colonized reduces the rate of postoperative infections by >50%. ^{, ,} No data exists to support the use of routine decolonization protocols in patients who are not found to be colonized with S. aureus .

Antibiotic Prophylaxis

Preoperative antibiotic prophylaxis has been shown to significantly reduce the risk of SSIs, and the incidence of wound infection by approximately 50%, regardless of the type of surgery. Antibiotic prophylaxis ( Table 74.4 ) is recommended for implantable pain therapies (i.e. trials and implant stages). Proper antibiotic selection, route of administration, dosing, and timing are critical, as suboptimal implementation has increased the risk of infection by two- to six-fold. ^, Cephalosporins are recommended as first line agents. Clindamycin or vancomycin are alternative antibiotics if a patient has a β-lactam allergy. In individuals colonized with MRSA or at high risk for MRSA (e.g., institutions with a high rate of MRSA infections), vancomycin is recommended. ^, In individuals with vancomycin allergies, daptomycin may be considered.

For effective antibiotic prophylaxis, minimum inhibitory concentrations must be reached prior to surgical incision and maintained throughout the duration of the surgery. Therefore weight-based dosing is critical. Preoperative antibiotics should be administered intravenously (IV) prior to breaching the skin (30–60 min or 120 min for vancomycin). Re-dosing is needed when the duration of surgery is longer than two half-lives of the administered antibiotic ( Table 74.5 ).

The continuation of antibiotics in the postoperative period is not recommended beyond 24 h for clean surgical wounds. Prolonged antibiotic use in the postoperative period does not improve outcomes and may result in poorer outcomes. ^, Specifically, the continuation of antibiotics in the postoperative period has been associated with delayed normalization of body temperature and elevated C-reactive protein level. The SCIP guidelines recommend discontinuation of antibiotics within 24 h of surgery.

There are no recommendations or evidence for the use of antibiotic prophylaxis in the majority of routine interventional pain procedures, i.e. such as epidural steroid injections and facet blocks. However, for procedures with a higher risk of infection (i.e. indwelling catheters, kyphoplasty, and device trials/implants), antibiotic prophylaxis is recommended. ^, For discography and other intradiscal procedures, controversy exists regarding the need for IV and/or intradiscal antibiotic administration. ^,

Administration of intravenous antibiotics did not reliably achieve adequate intradiscal concentrations. Therefore only intradiscal antibiotics are recommended. However, ex vivo studies examining the effects of high antibiotic concentrations on cultured human intervertebral disc annular cells demonstrated deleterious effects on cell survival, cell proliferation, and metabolic rates; therefore these risks must be considered as well.

Surgical Hand Washing

Appropriate surgical scrubbing of the hands and forearms is a CDC Category IB and NICE recommendation. ^, Commercially available antiseptic solutions in the United States contain alcohol, chlorhexidine, and/or povidone iodine. There is evidence that chlorhexidine-based scrubs reduce the number of colony-forming units (CFUs) compared to povidone-iodine scrubs. However, data supporting its clinical relevance are lacking. Therefore there is a lack of strong evidence to strongly support the use of one agent over another. The duration of the surgical scrub appears to be the most important factor in ensuring adequate hand hygiene and limiting bacterial counts. Surgical hand washing lasting between 2 and 5 min results in statistically fewer CFUs than hand washing techniques of lesser duration.

The removal of hand and wrist jewelry prior to surgical scrub is a CDC Category II and NICE recommendation as well as a recommendation by the American Society of Anesthesiologists and American Society of Regional Anesthesia and Pain Medicine (ASRA) when performing neuraxial procedures. The presence of hand jewelry increases bacterial counts on the hands of healthcare workers even after hand washing. ^{, , ,}

The method of hand hygiene required to minimize the risk of infections associated with interventional pain procedures has not been established. A full surgical scrub is recommended for implantable and indwelling catheters.

Appropriate Hair Removal

The CDC Category IA and NICE do not recommend removing hair routinely to reduce the risk of SSI, and if hair is removed, clippers should be used. ^, The timing and method of hair removal appear to be the most important factors to consider. A meta-analysis examining hair removal techniques concluded that there was no difference in SSI rates when comparing no hair removal to hair removal with chemical or clipper methods. However, shaving methods increase the risk of SSIs. Both clipping and shaving hair 24 h or more before an operation significantly increases the risk of SSI. ^{, ,}

Patient Skin Preparation in the Operating Room

Antiseptic solutions containing isopropyl alcohol, povidone iodine, and chlorhexidine gluconate are most commonly used for skin preparation in patients. Prior to applying a skin antiseptic, gross contamination around the incision site should be removed (CDC Category IB).5 A randomized controlled trial and meta-analyses have shown that chlorhexidine significantly reduces the rate of SSIs and results in cost savings in comparison to povidone iodine.

For interventional pain procedures, the United States Food and Drug Administration has not approved the use of chlorhexidine for neuraxial procedures because of the lack of clinical safety trials. However, the use of chlorhexidine for spinal anesthesia has not been shown to increase neurologic complications. The use of chlorhexidine prior to epidural catheterization has been shown to be superior to povidone iodine in reducing catheter colonization rates. Although there are no studies directly comparing infection rates with the use of chlorhexidine gluconate versus povidone iodine for interventional pain procedures, based on extrapolation of data from other surgical subspecialties, chlorhexidine-based products may offer improvements in infection control rates.

Draping

Iodophor impregnated drapes may reduce the number of positive post-procedural skin cultures. However, there are no data to support their routine use for the reduction of SSIs. ^, While the use of iodophor impregnated drapes may be considered for high risk patients, the literature does not support universal usage.

Surgical Attire

Maximal sterile barrier precautions (surgical cap, mask, and sterile gloves and gowns) for surgical procedures are recommended by the CDC (Category IB), NICE, and SCIP. In 2004, the CDC and Healthcare Infection Control Practices Advisory Committee released a statement recommending the use of face masks for neuraxial procedures after eight cases of bacterial meningitis following neuraxial procedures were linked to practitioners who were not wearing masks.

Sterile gloves are recommended for interventional pain and implantable therapies. While there are no studies directly comparing the risk of SSIs with single versus double gloving techniques, double gloving has been shown in multiple studies to reduce the number of inner glove perforations. Glove perforations result in higher surgical infection rates. Therefore double gloving should be considered for implantable device surgeries to reduce the risk of SSI and protect the practitioner.