Lee et al reported risk factors for superficial incisional surgical site infections (SSI) in patients undergoing midline laparotomy. These can help to identify a patient who may benefit from more aggressive interventions to reduce the risk of this complication. The authors are from the University of Michigan
Patient selection: midline laparotomy
Risk factors for superficial incisional SSI:
(1) smoking
(2) therapy with corticosteroids
(3) longer operative time from incision to closure (odds ratio 1.2 per hour)
(4) ASA classification 1 or 2
(5) greater obesity as indicated by the normalized subcutaneous fat in the midline on abdominal CT (odds ratio 1.76 per 10% increase)
where:
• The mean operative time for patients without SSI was 3.7 hours vs 4.5 with SSI.
• Patients with ASA 3 to 5 had a lower rate of SSI than patients with ASA 1 or 2. Perhaps patients with ASA 4 or 5 did not live long enough to develop an SSI.
• The normalized subcutaneous fat was selected over body mass index (BMI) because the latter is a relatively nonspecific assessment of body composition that does not directly measure adiposity.
• The distribution of normalized subcutaneous fat was higher in women.
• If a CT scan is not available the subcutaneous fat can be measured at surgery. The visceral distance might be more difficult to measure.
normalized subcutaneous fat =
= (subcutaneous fat distance in mm) / (total anterior-posterior distance in mm) * 100%
total anterior-posterior distance =
= (subcutaneous fat distance from anterior skin to linea alba) + (distance for viscera from linea alba to the anterior edge of vertebral body)
