title: The effect of deep muscle relaxation on the force required during Latissimus Dorsi dissection for breast reconstructive surgery: results of a prospective, double-blinded observational pilot study.
abstract: The use of neuromuscular blocking agents has previously been suggested to facilitate the dissection of the latissimus dorsi muscle during breast reconstructive surgery. The aim of this study was to quantify the influence of deep muscle relaxation on the force required to lift the latissimus dorsi muscle during flap preparation.
  
  
  
  After ethics approval and written informed consent 15 patients scheduled for elective breast reconstruction with a latissimus dorsi pedicled flap (muscle flap, not myocutaneous flap) under general anaesthesia were prospectively included. Midway through the muscle dissection a sterile cotton tape was slung around the mid portion of the muscle and connected with a sterile strain gauge stably positioned just above the patient. Thereafter, the muscle was lifted by moving the strain gauge vertically upwards until a muscle tension similar to that created manually during muscle dissection was achieved. The force (N) and distance required to tension the muscle were recorded and the tension released. In a randomized and blinded crossover design either rocuronium (0.6 mg.kg-1) or normal saline were given intravenously, and the tension protocol was repeated 2 min after each drug administration.
  
  
  
  Muscle relaxation significantly reduced the force for flap tensioning (median [percentiles] - 22 [-32/-13] %; P = 0.011) in 10/15 patients. However, in the remaining 5 patients no significant effect was measured. Normal saline had no effect on the measured force.
  
  
  
  Deep muscle relaxation significantly reduces the force required to manually elevate the latissimus dorsi muscle during its dissection in the majority of but not all patients.
  
  
  
  The study was retrospectively registered on [17.6.2014] with the Australian and New Zealand Clinical Trials Registry. ACTRN12614000637640.
authors.affiliation: Anaesthesiology Unit in School of Medicine and Pharmacology, University of Western Australia, Level 2, Royal Perth Hospital Medical Research Foundation Building, Rear 50 Murray Street, Perth, WA, 6000, Australia. Thomas.ledowski@health.wa.gov.au.|Department of Anaesthesia and Pain Medicine, Royal Perth Hospital, 197 Wellington Street, Perth, WA, 6000, Australia. Thomas.ledowski@health.wa.gov.au.
authors.forename: T
authors.initials: T
authors.lastname: Ledowski
authors.affiliation: Department of Plastic and Reconstructive Surgery, Royal Perth Hospital, 197 Wellington Street, Perth, WA, 6000, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Goodwin-Walters
authors.affiliation: Department of Plastic and Reconstructive Surgery, Royal Perth Hospital, 197 Wellington Street, Perth, WA, 6000, Australia.
authors.forename: P
authors.initials: P
authors.lastname: Quinn
authors.affiliation: Department of Anaesthesia and Pain Medicine, Royal Perth Hospital, 197 Wellington Street, Perth, WA, 6000, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Calvert
mesh_terms: D000732:Androstanols / Q000008:administration & dosage*; D000768:Anesthesia, General; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D016462:Mammaplasty; D008875:Middle Aged; D009126:Muscle Relaxation; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage*; D010865:Pilot Projects; D011446:Prospective Studies; D000077123:Rocuronium; D064171:Superficial Back Muscles / Q000637:transplantation*; D013524:Surgical Flaps
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium
keywords: Breast reconstructive surgery; Latissimus dorsi flap; Muscle tension; Neuromuscular blocking agents; Rocuronium