title: The association of hypotension with the insertion of an abdominal retractor during lower abdominal surgery in pediatric patients: a retrospective observational study.
abstract: BACKGROUND
  The Alexis(®) wound retractor is composed of an inner- and outer-ring, with the inner-ring placed inside the abdominal cavity. This placement can constrict the internal organs and large vessels, especially in children, which can lead to hypotension. Our study aimed to investigate the relation between the incidence of hypotension and insertion of the wound retractor during lower abdominal surgery in pediatric patients.
  
  
  METHODS
  We retrospectively examined 161 pediatric patients (<4 years old), who underwent lower abdominal surgery, regardless of abdominal retractor type. Hypotension was defined as a decrease in systolic blood pressure of >15% from baseline. We used logistic regression to predict hypotension using the following nine parameters: age, height, weight, American Society of Anesthesiologists physical status (ASA-PS), sex, laterality of the operation (unilateral or bilateral), presence or absence of caudal block, wound length, and type of retractor (retractors with or without an inner-ring).
  
  
  RESULTS
  Logistic multivariate regression analysis revealed that a retractor with an inner-ring use (odds ratio 3.28, 95% CI 1.41-7.63, P = 0.006) and younger age (odds ratio 1.07 per month, 95% CI 1.02-1.12, P = 0.010) were independent risk factors associated with hypotension following lower abdominal surgery in this age group.
  
  
  CONCLUSIONS
  Patient age and use of a wound retractor with an inner-ring are independent risk factors associated with hypotension during insertion of the abdominal retractor in lower abdominal surgery.
authors.affiliation: Department of Anesthesia, Kanagawa Children's Medical Center, Yokohama, Japan.
authors.forename: Rika
authors.initials: R
authors.lastname: Nakayama
authors.affiliation: Department of Anesthesia, Kanagawa Children's Medical Center, Yokohama, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mihara
authors.affiliation: Department of Anesthesia, Kanagawa Children's Medical Center, Yokohama, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Miyamoto
authors.affiliation: Department of Anesthesia, Kanagawa Children's Medical Center, Yokohama, Japan.
authors.forename: Koui
authors.initials: K
authors.lastname: Ka
mesh_terms: D000005:Abdomen / Q000601:surgery*; D000367:Age Factors; D002675:Child, Preschool; D013505:Digestive System Surgical Procedures / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D005260:Female; D006801:Humans; D007022:Hypotension / Q000209:etiology*; D007223:Infant; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors
keywords: adverse events; child; hypotension; infant; logistic regression