Nutrition

More has been reported about the relationship between infection and nutrition in the general surgery and critical care literature than the spine literature.^5–9 Often such studies involve polytrauma and burn victims in severe catabolic states. However, the principles involved apply to elective spine surgery as well.

A study by Klein et al.¹⁰ followed three groups of patients and analyzed infections and other complications against markers of nutritional status. Patients were deemed nutritionally replete if they had a serum albumin of at least 3.5 g/dL and an absolute lymphocyte count (a stable immune marker) of at least 1500 cells/mm³. Patients falling below either or both of these cutoffs were considered malnourished.

In a group of 114 patients undergoing elective spinal procedures, a total of 85 were found to be replete prior to surgery, and 29 malnourished. The former group had a total of 2 complications, and the latter 11, a difference that is even more dramatic considering the disparate sizes of the groups. Of note, they found that 40% of patients older than 60 years were malnourished. They found similar results among patients who were operated on for spondylodiscitis, as well as spinal cord injury.

Considering the aforementioned, a reasonable nutrition assessment and management approach would be to check serum albumin and absolute lymphocyte counts preoperatively, especially in older patients. If abnormal, surgery should be deferred until a nutrition consult is obtained and the patient is nutritionally replete.

Antiseptic Shower

The use of antiseptic showers, either with povidone-iodine (Betadine) or chlorhexidine gluconate (CHG), has been advocated by some. A study of 700 surgical patients demonstrated a reduction of bacterial skin colonization with either soap, by a factor of 1.3-fold with iodine and 9-fold with CHG.¹¹ Similar results have been found elsewhere.¹² Although evidence to support a clear reduction in SSIs is lacking,¹³ a bottle of CHG solution sufficient for two preoperative showers costs about $9 US at the time of this writing, and its use is likely of great enough benefit to offset that minor cost. Thus, the practice is recommended.

Mupirocin Nasal Ointment

Staphylococcus aureus is the leading cause of SSIs in clean surgical procedures, including spinal operations. An association has been noted between nasal carriage of S. aureus in patients and the occurrence of SSIs. Twenty-five percent to 30% of the U.S. population are nasal carriers of S. aureus at any given time.¹⁴ A short course of treatment with mupirocin (Bactroban) ointment has been shown to eliminate S. aureus in many of these carriers.

To date, two randomized, controlled trials (RCTs) have been conducted to evaluate the efficacy of preoperative mupirocin ointment usage in reducing SSI rates.^14,15 Both studies showed a trend toward efficacy, but neither was significant. A later analysis showed that pooling of the results showed a nearly significant decrease in the infection rate.¹⁶ However, when all nosocomial S. aureus infections (not just SSIs) among patients with nasal S. aureus were considered, the study from Perl et al. did show a statistically significant decrease in incidence with the use of mupirocin ointment.¹⁴

At this point, it is difficult to advocate the widespread use of mupirocin ointment preoperatively, considering the lack of convincing evidence showing benefit, as well as the cost (about $40 US). However, a rapid screening test for S. aureus that uses polymerase chain reaction (PCR) technology has been developed¹⁷ and has shown excellent sensitivity and specificity. This has allowed treatment targeted only toward carriers, which shows promise.¹⁸ It is reasonable to expect that within the next several years this technology will be more widely accessible. If so, it could allow for the selective treatment of carriers, which would be expected to demonstrate a beneficial effect.

Hair Removal

Possibly one of the most ingrained practices in all of surgery is shaving the skin prior to an operation. Unfortunately, it is probably also detrimental. Removing hair by shaving with a razor has been compared with the use of electric clippers in three RCTs.^19–21 These trials were similar in design and focused on clean operations (general and cardiac procedures), so their results were pooled in a recent Cochrane review.²² This yielded a total of 3193 patients, divided nearly evenly between shaving (1627) and clipping (1566). The infection rate was 2.8% for the former group, and 1.4% for the latter, yielding a relative risk (RR) of 2.02, which surpassed statistical significance.

In addition to this strong evidence against shaving, two other points can be made. First, there is no good evidence to show that hair removal lowers the infection rate. The step may be omitted entirely. Second, depilatory creams have been associated with a lower infection rate than shaving in several trials²²; this provides another alternative to razors should complete hair removal be desired.

Razors should only be used for hair removal with the clear understanding that their use has been associated with higher infection rates in several large, well-designed trials.

Skin Preparation

The rationale for preparing the skin prior to incision is twofold. First, the mechanical scrubbing of the skin removes dirt, as well as some bacteria and dead skin cells. Second, the prep solution should have an intrinsic bactericidal and/or bacteriostatic effect.

Commonly employed agents contain alcohol (isopropyl or ethyl), CHG, or iodine/iodophors. Alcohol has excellent activity against bacteria and good activity against mycobacteria, fungi, and viruses.²³ However, it cannot be used alone because it has essentially no residual activity once allowed to evaporate. Prior to evaporation it is flammable, which makes it incompatible with electrocautery.

CHG has good to excellent activity against bacteria and viruses. It is fair at eliminating fungi and has little activity against mycobacteria.²³ Its residual activity is excellent; however, it can cause keratitis and ototoxicity with serious consequences.

Triclosan (the active ingredient in dishwashing detergent) and parachlorometaxylenol (PCMX) are less efficacious and are not generally considered suitable for use in skin preparation or as surgical hand scrubs.

Given the clinical limitations of other preparations, CHG and iodophor solutions are most commonly used as surgical skin preps. CHG has been shown to reduce bacterial skin colonization to a greater degree than iodophors (see prior section), but no evidence yet demonstrates a lower SSI rate when using CHG.

Nevertheless, in a large RCT, CHG has been shown to reduce the line infection rate when compared with iodophor prep in the placement of central venous catheters.²⁴ A similar level of evidence does not yet exist for CHG as a surgical skin prep, but it is logical to expect that the superiority of CHG would hold true here as well. Thus, favoring CHG as a skin prep is advisable, provided that there is no risk of the solution entering the eyes or ears.

Handwashing

Several options exist here as well. Iodophor and CHG solutions are available and are commonly used with scrub brushes for a specified period of time. Ten minutes has been traditional, but there is no evidence to support this ritual; the U.S. Centers for Disease Control and Prevention (CDC) recommends a duration of 2 to 5 minutes.²³

In addition, waterless hand cleansers have recently come into more widespread use. Typical of these is Avagard (3M, St. Paul, MN). It consists of ethyl alcohol 61% w/w, CHG 1%, and a mixture of skin conditioners and fragrances.

Another category of hand cleaners includes water-aided, brushless formulations. Triseptin (Healthpoint Ltd., Fort Worth, TX) is one of these. It also contains ethyl alcohol 61% w/w, as well as a proprietary formulation of conditioners and fragrances. A large RCT has demonstrated equivalence of an aqueous alcohol-based hand rub with traditional handwashing techniques²⁵; the results of this trial can safely be extrapolated to the products available on the U.S. market.

Because most SSIs arise from the patient’s skin flora, the use of one type of hand cleanser over another is largely left to individual preference. If there is a difference amongst the different agents available, it is likely quite small and has yet to be proven. Guidelines from the CDC regarding this are available.²³

First, artificial nails should be avoided. They can harbor micro-organisms and predispose gloves to tearing. A series of Serratia marcescens wound infections have been traced to a surgical team member with artificial nails.²⁶ Second, fingernails should be kept short and neat. Third, cleaning under the nails is recommended, as is removal of jewelry on the hands and arms, but the scientific support for this is overshadowed by the clear theoretical basis on which these recommendations are founded.

Surgical Gowns

The U.S. Occupational Safety and Health Administration (OSHA) requires that gowns have a minimum level of strikethrough resistance. All of the commercially available, disposable surgical gowns in the United States meet this standard. Porous cloth gowns have generally been eliminated because they do not offer this protection to the patient or to the surgeon.

Some have recommended that gowns and gloves be changed every 1.5 to 2 hours during lengthy cases.²⁷ Although this recommendation is sensible, the cost of this practice must also be considered.

Double-Gloving

The practice of double-gloving has been advocated as a protection to both the medical staff and the patient. For the staff, the risk of transmission of a communicable disease, such as HIV or hepatitis, is likely reduced, as is the risk of gross contamination through a compromised glove. Not only is perforation of two gloves more difficult than one, but in the event of a needlestick, the “squeegee effect” of the second glove has been shown as well.²⁸

Double-gloving may reduce the risk of SSI as well. Perforation rates of greater than 20% have been reported for the primary operator.^29,30 This puts the surgeon’s skin in direct contact with the surgical bed, increasing the chance of bacterial contamination for the patient and creating a hazardous exposure for the surgeon.

Although the superiority of double-gloving in prevention of SSI has not been shown, a perusal of a recent Cochrane review reinforces the theoretical benefit of double-gloving to the patient.³¹