Surgical Prophylaxis PDF

Surgical Prophylaxis Surgical Prophylaxis Definition Antibiotics administered before contamination of previously sterile tissues or fluids are considered prophylactic. The goal of prophylactic antibiotics is to prevent an infection from developing Common surgical pathogens *The predomi...

Surgical Prophylaxis Surgical Prophylaxis Definition Antibiotics administered before contamination of previously sterile tissues or fluids are considered prophylactic. The goal of prophylactic antibiotics is to prevent an infection from developing Common surgical pathogens *The predominant organisms causing SSIs after clean procedures are skin flora, including S. Aureus and coagulase-negative staphylococci (e.g., Staphylococcus epidermidis) *In clean-contaminated procedures, including abdominal procedures and heart, kidney, and liver transplantations, the predominant organisms include gram negative rods and enterococci in addition to skin flora (6)  Antimicrobial selection The choice of the prophylactic antimicrobial depends on the type of surgical procedure, most likely pathogenic organisms, safety and efficacy of the antimicrobial, current literature evidence supporting its use and cost. Typically, gram-positive coverage is included in the choice of surgical prophylaxis because organisms such as S. aureus and S. epidermidis are common skin flora. Parenteral antibiotic administration is favored because of its reliability in achieving suitable tissue concentrations. First-generation cephalosporins (particularly cefazolin) are the preferred choice, particularly for clean surgical procedures. Anti anaerobic cephalosporins (eg, cefoxitin or cefotetan) are appropriate choices when broad-spectrum anaerobic and gram negative coverage is desired. Vancomycin may be considered for prophylactic therapy in surgical procedures involving implantation of a prosthetic device in which the rate of me. aureus (MRSA) is high. If the risk of MRSA is low and a β-lactam hypersensitivity thicillin- resistant Sexists, clindamycin can be used instead of cefazolin in order to limit vancomycin use. Current literature evidence supporting its use and cost (1). Types of Surgical Operations Surgical operations are classified as clean, clean -contaminated, contaminated, or dirty. Antimicrobial prophylaxis is appropriate for clean, clean-contaminated, and contaminated operations. Dirty operations take place in situations of existing infection and antimicrobials are used for treatment, not prophylaxis (3). (Table 1)  Principles of Antimicrobial Prophylaxis 1-Route of Administration Intravenous administration is preferred because it produces a more reliable and predictable serum and tissue concentration than intramuscular administration Oral administration is also used in some bowel operations. Non- absorbable compounds like erythromycin base and neomycin are given up to 24 hours prior to surgery to reduce microbial concentrations in the bowel. Note that oral agents are used adjunctively and do not replace IV agents  Timing of First Dose For prevention of SSIs, correct timing of antimicrobial administration is imperative so as to allow the persistence of therapeutic concentrations in the blood and wound tissues during the entire course of the operation. The National Surgical Infection Prevention Project recommends infusing antimicrobials for surgical prophylaxis within 60 minutes of the first incision A single dose of antibiotic should be administered within 30 minutes to one hour before incision ) (They are given 15-60min prior to the procedure) (Exceptions to this rule are fluoroquinolones and vancomycin, which can be infused 120 minutes prior to avoid infusion-related reactions. Beginning the infusion after the first incision is of little value in preventing SSI  Dosing and Redosing The goal of antimicrobial dosing for surgical prophylaxis is to maintain antibiotic concentrations above the MIC of suspected organisms for the duration of the operation If an operation exceeds two half-lives of the selected antimicrobial, then another dose should be administered. Repeat dosing has been shown to lower rates of SSI. For example, cefazolin has a half life of about 2 hours, thus another dose should be given if the operation exceeds 4 hours. The clinician should have extra doses of antibiotic ready in case an operation lasts longer than planned  Duration The National Surgical Infection Prevention Project and published evidence suggest that the continuation of antimicrobial prophylaxis beyond wound closure is unnecessary. The duration of antimicrobial prophylaxis should not exceed 24 hours (48 hours for cardiac surgery) There is little evidence to support the practice of administering antibiotics until all drains are removed. Continuing the antibiotic does not necessarily reduce the infection rate. Moreover, it can encourage proliferation of resistant micro-organisms and subject patients to increased antibiotic- associated morbidity. Prolonged prophylaxis using antibiotics is also unnecessarily expensive. Longer durations of antibiotic prophylaxis are advocated by some guidelines  Combination antimicrobial therapy Combinations of antimicrobials are generally used to broaden the spectrum of coverage for empiric therapy, achieve synergistic activity against the infecting organism, and prevent the emergence of resistance. Increasing the coverage of antimicrobial therapy is generally necessary in mixed infections in which multiple organisms are likely to be present, such as intraabdominal and female pelvic infections in which a variety of aerobic and anaerobic bacteria may produce disease. Another clinical situation in which increased spectrum of activity is desirable is with nosocomial infection. Disadvantages of Combination Therapy including increased cost, greater risk of drug toxicity, and superinfection with even more resistant bacteria. Thromboprophylaxis Deep venous thrombosis (DVT) is most common in patients over 40 years of age who undergo major surgery. A postoperative increase in platelets coupled with venous endothelial trauma and stasis all contribute. If no prophylaxis is given, 30% of these patients will develop DVT and 0.1-0.2% will die from pulmonary thromboembolism (PTE) Types of thromboprophylaxis 1-Mechanical devices: Thromboembolic deterrent stockings (TEDS). 2-Drugs acting on the clotting cascade: Heparin and Low molecular weight heparin (LMWH). Regimen heparin 5000U SC 2h pre-op, then every 8-12h SC for 7d or until ambulant. Low molecular weight heparin (LMWH, eg enoxaparin 20mg/24h SC, increased to 40mg for high-risk patients, starting 12h pre-op) Fondaparinux (a factor Xa inhibitor) reduces risk of DVT over LMWH without increasing the risk of bleeding. Risk groups All patients are -at risk of developing deep vein thrombosis just as is the general population. National requirements for VTE prophylaxis require all patients to be assessed for risk factors on admission and after 24h in hospital. Risk is judged according to: Procedure factors. Prolonged anesthetic time, lower limb or pelvic surgery. Patient factors. Immobility, malignancy, age, dehydration, obesity, diabetes, cardiorespiratory disease, inflammatory pathologies, oral contraceptive pill or hormone replacement therapy (HRT), past or family history of thromboembolic disease. Balanced against: Bleeding risks. Active bleeding, stroke, invasive procedures, bleeding disorders (liver disease, thrombocytopenia, inherited disorders). Risks of compression devices. Peripheral vascular disease (PVD).