Perioperative antibiotic prophylaxis in adults - Sistema Nazionale ...

colleagues 32 , confirmed by national data 16 , operations lasting more than the 75 thpercentile for the procedure in question are classified as prolonged (see Annex 5, p. )and therefore at increased risk.ComorbitiesThe American Society of Anesthesiologists (ASA) has developed a system forscoring preoperative risk based on the presence of comorbities at the time of surgery(see Table 4, p. ) 36 . An ASA score >2 is associated with increased risk of woundinfection, which is added to that of the class of operation and its duration 32 .Table 4 American Society of Anesthesiologists ClassificationASA scorePhysical status1 healthy patient2 patient with mild systemic disease3 patient with severe systemic disease that limitsactivity but is not incapacitating4 patient with incapacitating systemic disease thatis a constant threat to life5 moribund patient who is not expected to survivemore than 24 hours with or without surgeryProbability of surgical site infectionEarlier guidelines referred to patients at high risk of SSI but gave no clearinformation about predicting the risk. This section is intended to illustrate howcomorbidity and duration of surgery affect the risk defined by the class of operation.The duration of surgery and comorbidities (according to the ASA score) have thesame impact on the risk of wound infection as the class of operation.To define the risk, two factors other than the class of operation need to be considered:• the presence of comorbities (with ASA score >2 the risk of SSI increases);