title: Low- vs. high-pressure suction drainage after total knee arthroplasty: a double-blind randomized controlled trial.
abstract: OBJECTIVE
  The aim of this study was to assess the efficacy of continuous low-pressure suction drainage compared with closed high-pressure suction following total knee arthroplasty.
  
  
  BACKGROUND
  Closed wound drainage systems are used in surgical interventions to reduce the incidence of haematomas, promote wound healing and reduce infections. However, evidence shows that using a closed wound drainage system can increase transfusion requirements.
  
  
  METHODS
  A randomized, double-blind and parallel controlled trial was performed. Adult knee replacement patients recruited between May 2006 and March 2007 were assigned to receive low-pressure suction of 50 mmHg (experimental drainage) or high-pressure suction of 700 mmHg (comparator drainage).
  
  
  METHODS
  The primary outcome was total blood loss after surgery. Secondary outcomes were incidence of transfusion, complications and mortality. Statistical analysis was based on an intention-to-treat approach. Linear regression was performed to account for factors that could influence blood loss.
  
  
  RESULTS
  A total of 169 patients were included. Mean age was 73 (±6) years, 128 women and 41 men. A total of 84 patients were randomized to the experimental drainage and 85 to the comparator drainage. Analysis showed a total postoperative blood loss of 541·8 mL in the experimental group and 524·4 mL in the comparator group (P = 0·734). The only factor that showed an association with blood loss was the length of surgery. Linear regression did not show differences between the groups.
  
  
  CONCLUSIONS
  Continuous low-pressure suction of 50 mmHg is not more effective than the higher aspiration pressure system to diminish the blood loss in total knee arthroplasty. The results do not support any change in current nursing practice relating to the use of this drain system.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, IIIB Sant Pau, Barcelona, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Calvo
authors.forename: Ma José
authors.initials: MJ
authors.lastname: Martínez-Zapata
authors.forename: Gerard
authors.initials: G
authors.lastname: Urrútia
authors.forename: Ignasi
authors.initials: I
authors.lastname: Gich
authors.forename: Marcos
authors.initials: M
authors.lastname: Jordán
authors.forename: Alejandro
authors.initials: A
authors.lastname: Del Arco
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Aguilera
authors.forename: Fernando
authors.initials: F
authors.lastname: Celaya
authors.forename: Juan
authors.initials: J
authors.lastname: Sarasquete
authors.forename: Joan
authors.initials: J
authors.lastname: Majó
authors.forename: Xavier
authors.initials: X
authors.lastname: Bonfill
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods* / Q000534:rehabilitation; D001803:Blood Transfusion / Q000706:statistics & numerical data; D004311:Double-Blind Method; D004322:Drainage; D005260:Female; D006406:Hematoma / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D057194:Intention to Treat Analysis; D016014:Linear Models; D008297:Male; D016530:Orthopedic Nursing / Q000379:methods; D011182:Postoperative Care; D019106:Postoperative Hemorrhage / Q000517:prevention & control*; D011312:Pressure; D013396:Suction / Q000379:methods*; D016896:Treatment Outcome; D014945:Wound Healing