A Quality Initiative to Improve Glycemic Control in Diabetic and Non-Diabetic Insulin Study
Condition: Glycemic Control; Surgical Site Infections; Cardiac Complications; Length of Stay; Cost
MeSH terms: Surgical Wound Infection
Study type: Observational

Summary: 
      The aim of this study is to examine the effect of moderate glucose (blood sugar) control in
      diabetic and non-diabetic patients undergoing leg bypass surgery (LEB) or open abdominal
      aortic aneurysm (AAA) repair. We hypothesize that use of Fletcher Allen Health Care's current
      insulin infusion strategy will result in improved blood sugar control which will translate
      into decreased postoperative morbidity (fewer complications) and better long term outcomes
      when compared to patient outcomes at other institutions which utilize other blood sugar
      management strategies.
    

Detailed description: 
      We plan a concurrent, matched cohort study of moderate postoperative glucose control in
      patients undergoing leg bypass or open AAA repair. Consecutive patients undergoing elective
      open AAA repair or leg bypass will be enrolled over a two year period. A population of
      de-identified patients from other institutions in the region matched for medical problems who
      did not receive an insulin infusion will be used as a control group.

      Continuous intravenous insulin protocol The insulin infusion strategy is local standard of
      care for control of postoperative hyperglycemia after leg bypass surgery. Blood glucose
      monitoring is standard after open AAA surgery but the method of glucose control could range
      from sliding scale insulin to the use of an insulin infusion.

      Diabetic and non-diabetic patients will be placed on the existing Fletcher Allen Health Care
      standardized algorithm of continuous IV insulin immediately after surgery and continued for
      72 hours. The insulin infusion will be initiated if/ when the finger stick blood glucose is
      greater than or equal to 120 mg/dL, with a target titration goal between 80-150 mg/dL. The
      insulin infusion will be adjusted based on a defined algorithm in use at Fletcher Allen
      Health Care.

      Primary outcome measures:

        1. Glycemic control as measured by mean daily glucose levels and mean daily glucose
           excursions. We will look at the patients' finger-stick records and record the time spent
           at goal glucose levels, 80 to 150 mg/dL.

        2. Surgical site infection (SSI) in-hospital will be defined according to the Centers for
           Disease Control definition16 as an infection that occurs within 30 days after the
           operative procedure and involves only skin and subcutaneous tissue of the infection and
           includes one of the following:

             1. purulent drainage from superficial incision

             2. organisms isolated from an aseptically obtained culture of fluid or tissue from the
                superficial incision

             3. at least one of the following signs or symptoms of infection: pain or tenderness,
                localized swelling, redness, or heat and the incision is deliberately opened by the
                surgeon, and is culture positive or not cultured. Culture negative does not meet
                this criterion.

             4. Diagnosis of superficial incisional SSI by the surgeon or attending. . 3. Surgical
                site infection at 30 days.

      Secondary outcome measures:

        1. Moderate to severe hypoglycemic or hyperglycemic events as defined by moderate
           hypoglycemic event as <66 mg/dl and severe hypoglycemic event as <50 mg/dl and moderate
           hyperglycemic event as >250 mg/dl and severe hyperglycemic event as >500 mg/dl.

        2. Composite cardiac complications: myocardial infarction, congestive heart failure and
           clinically significant arrhythmias within 30 days of surgery,

        3. Hospital length of stay, re-admission and total costs of the hospitalization. Cost data
           will be obtained through Fletcher Allen Health Care administrative data. At the
           patient's 4 week follow up they will be asked if since their discharge have they had any
           health related visits; if so what type and for anything possibly related to the surgical
           procedure obtain the participants permission (in writing) to gather that data from the
           other provider.
    

Intervention name(s): standard insulin protocol post-op (continuous IV insulin)
Intervention type(s): Drug
Intervention description(s): concurrent, matched cohort study of moderate postoperative glucose control in patients undergoing LEB or open AAA repair.Propensity score matching is a statistical method used to reduce the confounding effects of covariates in an observational (non-randomized) study. In practice we will select a number of variables that impact wound infection; age, gender, diabetic and non-diabetic populations, renal insufficiency (defined at creatinine ≥1.8) and indication for surgery (claudication or critical limb ischemia with rest pain or tissue loss or open AAA repair); and chose a group of patients in the Vascular Study Group matched for these variables who have not been treated with an insulin infusion). Consecutive patients undergoing elective open AAA repair or infrainguinal LEB for claudication and critical limb ischemia will be invited to enroll in the study.
Intervention MeSH terms: Insulin
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        LEB and open AAA patients