Appendix E. Study Parameters

Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Parameters for Fault Tree Development1

The parameters around surgical site infections addressed by this study fall into one of four categories: (1) procedural parameters; (2) temporal parameters; (3) setting parameters; and (4) patient parameters. Table 1 details each parameter by category.

Table 1. Parameters for Fault Tree Development

ParameterDescriptionCategory
1. We will examine only surgical site infections stemming from arthroscopy of the knee.Based upon technical expert panel judgment and database analyses, it was determined that arthroscopy of the knee is the most robust area for examination. We based this decision largely on the expertise of the surgeons on our TEP and the large number of arthroscopies listed in the SASD and linked to SEDD and NIS data.Procedural
2. We will examine only deep incisional surgical site infections.Based upon database analyses and expert input, we will examine only deep site infections as defined by the Centers for Disease Control. A deep incisional SSI must meet one of the following criteria: (1) infection occurs within 30 days after the operative procedure if no implant is left in place or within one year if implant is in place and the infection appears to be related to the operative procedure; and (2) involves deep soft tissues (e.g., fascial and muscle layers) of the incision; and (3) patient has at least one of the following: (a) purulent drainage from the deep incision but not from the organ/space component of the surgical site; (b) a deep incision spontaneously dehisces or is deliberately opened by a surgeon and is culture-positive or not cultured when the patient has fever (>38°C), or localized pain or tenderness; (c) an abscess or other evidence of infection involving the deep incision is found on direct examination, during reoperation, or by histopathologic or radiologic examination; or (d) diagnosis of a deep incisional SSI by a surgeon or attending physician.Procedural
3. We will limit our temporal period of interest ranges from the pre-operative call to 30 days beyond the procedure.Based upon expert panel judgment and available data in the extant literature, we will limit fault tree modeling to the period ranging from the pre-operative checklist call conducted by ASC/Physician staff (1 week to 1 day prior to procedure) to 30 days beyond the actual procedure. Our technical experts indicate a likely 30-day incubation period for surgical site infections. This period will allow us to account for risk factors stemming from surgical center staff interaction, as well as patient care habits.Temporal
4. We will focus specifically on procedures performed in freestanding and/or hospital-affiliated ambulatory surgery centers.Based upon subject matter expertise on the AIR team and site visit interviews, we will limit fault tree modeling to procedures performed in freestanding and/or hospital-affiliated ambulatory surgery centers. Our site visits yielded critical information about sterilization and facilities management practices that might affect the introduction of microbes in the Pre-operative and Post Anesthesia Care stages of procedures.Setting
5. We will develop a fault tree accounting for patients who present at risk in the ambulatory surgery center.Based upon site visit data and expert panel input, we will develop a fault tree for patients who enter the ambulatory setting with a higher risk for potential infection. Patient factors considered include: (1) comorbid condition; (2) family/social situations; (3) insufficient preoperative optimization; and (4) condition influencing their health status (e.g., obesity, smoking).Patient
6. We will develop a fault tree accounting for patients introduced to a microbe (or infection) in the ambulatory surgery center.Based upon site visit data and expert panel input, we will develop a fault tree for patients introduced to a microbe in the ambulatory setting. Patient factors considered include: (1) staff hygiene/cleanliness (e.g., colonized with MRSA); (2) institutional processes and policies; (3) skin preparation techniques (e.g., hand washing, skin cleansing, draping); (4) sterilization policies for all equipment for the case (e.g., preparation of operative supplies, equipment, sterilization); (5) facility operations (e.g., cleanliness, sterilization procedures); (6) surgical and anesthetic issues such as surgical draping, breaks in sterile technique, and glucose control; and (7) post-operative care issues (e.g., patient factors, environmental factors, directions and understanding-dressing changes).Patient

1. The table presented in this appendix was extracted from Deliverable 2.1 for this project, Identification of Surgical Procedures and Parameters of Interest (April 8, 2011).

Page last reviewed April 2013
Internet Citation: Appendix E. Study Parameters: Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers. April 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/stpra/stpraape.html