What you do before and during surgery is important

A recent review article published in the Journal of the AAOS emphasized the important role that continuously correct intraoperative antibiotic levels play in preventing surgical site infections (SSIs). Surgeons who want to achieve new minimum rates of SSIs should move beyond concern about the number of postoperative antibiotic doses, which have not demonstrated any marginal benefit, and instead train with their operating room (OR) teams to provide the best preoperative and intraoperative interventions in a highly reliable manner.

By now, AAOS fellows are familiar with the first three process measures of the Surgical Care Improvement Project (SCIP)—giving antibiotic prophylaxis within 1 hour of incision, using an evidence-based antibiotic for each case, and stopping antibiotic prophylaxis within 24 hours of surgical end time. The Centers for Medicaid & Medicare Services now posts results for these measures on the Internet for every American hospital. Despite many years of work publicizing and educating physicians and other healthcare workers on these SCIP measures, none of them are reliably accomplished every time in most operating rooms.

Preoperative antibiotics
Surgeons and hospital staff who have studied the barriers to accurate and reliable administration of antibiotics found that case delays and other OR system problems often caused more than 60 minutes to elapse between administering the preoperative dose and making the skin incision. Most ORs have now re-engineered their dosing process to avoid premature antibiotic administration.

One common solution is to have the anesthesia provider administer preoperative cefazolin in the OR. Cefazolin, because of its short half-life, rapid tissue penetration, and low toxicity, can be given intravenously (IV) after anesthesia induction and prepping and draping. Administration of vancomycin, when necessary, is more problematic because it must be given more slowly, over at least 1 hour. The SCIP process measure allows a 2-hour window for administration of vancomycin, when indicated.

Postoperative antibiotics
During the past decade, most orthopaedists have shortened their recommended postoperative antibiotic prophylaxis from 48 or 72 hours to 24 hours or less. Most published evidence demonstrates that antibiotic prophylaxis beyond the time of wound closure does not provide any additional protection against SSI for routine elective cases. Studies in high-risk immuno-compromised patients are still lacking, however.

Perioperative antibiotics
An increasing body of evidence supports the primary importance of achieving and maintaining adequate antibiotic tissue levels while the wound is open. Recommendations include adjusting the perioperative dose according to the patient’s body mass (for example, doubling the cefazolin dose to 2 g in patients heavier than 80 kg), and repeating the dose during surgery if heavy blood loss occurs or if the surgery lasts longer than two half-lives of the antibiotic.

Although cefazolin is commonly ordered intravenously every 8 hours for steady-state equilibrium levels, the drug’s half-life is actually only 1.5 to 2.5 hours in normal patients. Because surgical prophylaxis is a loading dose, cefazolin should be readministered during surgery if the procedure lasts longer than 3 hours.

Taking a leadership role
Rather than focusing on the number of postoperative antibiotic doses—a practice that has not shown benefit for our patients—orthopaedic surgeons should apply their knowledge of team leadership techniques and systems design to reliably deliver evidence-based treatment to their patients. This cannot be accomplished just by writing an order. Achieving a highly reliable OR requires engagement and problem solving with a multidisciplinary team of surgical professionals.

When appropriate tissue levels of antibiotic are achieved prior to skin incision for every indicated procedure, and adequate levels are maintained throughout the surgical period, patients receive the best protection from SSIs. They may safely begin their rehabilitation without the encumbrance and risk of unnecessary postoperative IVs and medications.

Orthopedic surgeons can maintain their leadership in patient safety by partnering with other surgical and healthcare professionals to design reliable and efficient systems that deliver evidence-based surgical care. Members of the AAOS Patient Safety Committee, which now includes the Infections Committee, will present an Instruction Course Lecture on “Antibiotics in Orthopaedic Surgery: An Emerging Paradigm” during the 2009 Annual Meeting in Las Vegas. Be certain to join them on Thursday, Feb. 26 at 1:30 p.m. for case presentations and tips on reducing infection risk.

References for the studies cited in this article may be found in the online version available at www.aaosnow.org

Robert Brooks, MD, PhD, MBA, is chair of the AAOS Patient Safety Committee. He can be reached at bobbrooksster@gmail.com

Reference:

1. Prokuski, L. Prophylactic Antibiotics in Orthopaedic Surgery, J Am Acad Orthop Surg 2008; 16: 283-293