title: Tourniquet release: systemic and metabolic effects.
abstract: The pneumatic tourniquet produces ischemic changes in limbs. The effects of tourniquet release on systemic blood pressure and metabolic parameters were studied in 11 adult patients undergoing total knee replacement under general anesthesia. Mean arterial pressure (MAP) decreased rapidly after the release of the tourniquet, becoming significant at 3 min and remaining significantly depressed up to 15 min post release. Arterial pH, PaO2, PaCO2, lactate acid, and potassium changed significantly after the release, but normalized within 30 min. These results are notably different from a previous study in a similar patient population undergoing knee replacement under epidural anesthesia. Compared to patients under epidural anesthesia, patients receiving general anesthesia with mechanical ventilation are unable to compensate for the metabolic load caused by the tourniquet release, as the latter group are unable to alter their ventilatory rate. In elderly patients with decreased cardio-pulmonary reserve, this may be of clinical importance.
authors.affiliation: Department of Orthopedic Surgery, Stanford University Medical Center, California, USA.
authors.forename: H S
authors.initials: HS
authors.lastname: Townsend
authors.forename: S B
authors.initials: SB
authors.lastname: Goodman
authors.forename: D J
authors.initials: DJ
authors.lastname: Schurman
authors.forename: A
authors.initials: A
authors.lastname: Hackel
authors.forename: J G
authors.initials: JG
authors.lastname: Brock-Utne
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000768:Anesthesia, General; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007720:Knee Prosthesis; D008875:Middle Aged; D012121:Respiration, Artificial; D014111:Tourniquets
chemical_list: D002245:Carbon Dioxide