Does Deep Neuromuscular Blockade Improve Operating Conditions During Total Hip Replacements?
Condition: Arthropathy of Hip
MeSH terms: Joint Diseases
Study type: Interventional
Phase: Phase 4

Summary: 
      During many surgeries, increased muscle tension makes it harder for the surgeon to expose the
      site of surgery and work within the incision. Neuromuscular blockade (NMB) drugs such as
      Vecuronium bind to neurotransmitter (acetyl choline) receptors at the neuromuscular junction,
      blocking their action and producing muscle relaxation. This muscle relaxation allows easier
      retraction of muscle tissues and manipulation of structures in the wound. Improved surgical
      conditions are likely to result in improved patient outcomes. While increased depths of NMB
      have been shown to optimize surgical conditions during intra-abdominal and retroperitoneal
      procedures, the impact of NMB depth has not been reported for orthopedic surgeries.1 To
      address this, we propose to study the effect of NMB depth on surgical conditions during total
      hip replacement (THR).
    

Detailed description: 
      Specific Aims

        1. Assess difference in surgical conditions between moderate and deep NMB groups. Enrolled
           patients will be randomized to receive moderate (n=58) or deep (n=58) NMB. Difference in
           surgical conditions will be evaluated by:

             1. The number of requests from the surgeon for additional relaxation (NMB) during the
                procedure. At any time during the operation if the surgeon feels the muscle tension
                is interfering with ease of operation he will ask for additional muscle relaxation.
                If the patient is moderately relaxed they will be converted to deep relaxation with
                additional muscle relaxants. If they are already deeply relaxed no additional
                relaxants will be administered (as is our current practice). All requests will be
                recorded.

             2. Rating by the surgeon after each surgery using an internally developed satisfaction
                scale. The scale was developed by modifying a scale used in a previous study of
                muscle relaxation in intra-abdominal surgery1 to specify two key elements
                identified by our surgeon: ease of muscle retraction and femur manipulation.

        2. Assess the impact of deep vs moderate NMB on time of surgery, measured from the time of
           incision to joint reduction.

      SIGNIFICANCE If we identify improved surgical conditions with deeper relaxation we will
      incorporate deep NMB into our routine anesthesia practice for THR.

      Vecuronium will be used as NMB drug in all study patients; this agent is currently used in
      over 90% of THR cases at Maine Medical Center (MMC). As is currently routine Vecuronium will
      be given after initiation of general anesthesia with propofol to facilitate intubation and
      further doses of Vecuronium will be given throughout the case as noted below to maintain NMB
      at the desired depth until the femoral implant is reduced. After the intubating dose of
      Vecuronium, NMB depth will be monitored every 5 minutes and dosing will be adjusted as needed
      to maintain a constant depth of NMB according to our current routine practice.

      Group 1: Moderate NMB: Intubating dose of Vecuronium of 0.1 mg/kg (IBW) and re-dosing with
      0.0125 to 0.05 mg/kg as needed to achieve and maintain 1 to 2 train of four (TOF)
      contractions. Redosing in this manner is a current clinical practice.

      Group 2: Deep NMB: Intubating dose of Vecuronium of 0.2 mg/kg (IBW) and re-dosing with 0.025
      to 0.1 mg/kg to achieve and maintain zero twitches in the TOF, and post tetanic count (PTC)
      of 1 to 2 contractions. This level of blockade is new to the practice since approval of the
      drug for use at MMC but is in common use since the advent of Sugammadex.

      The surgeon may request additional relaxation at anytime for inadequate surgical conditions
      thought to be related to muscle tension. All requests will be recorded. Patients in the
      moderate NMB group will receive additional doses of vecuronium to achieve deep NMB (PTC of 1-
      2). In the deep NMB group with PTC of 1-2, a saline dose without NMB will be given.

      NMB reversal Sugammadex will be given for reversal of NMB after the prosthesis has been
      reduced, using routine dosing of 2 mg/kg for the moderate group and 4 mg/kg for the deep
      group, per package insert by Merck.
    

Intervention name(s): Vecuronium 0.1 mg/kg; Vecuronium 0.2mg/kg
Intervention type(s): Drug; Drug
Intervention description(s): Vecuronium will be administered to achieve and maintain 1 to 2 TOF contractions.; Vecuronium will be administered to achieve and 0 TOF/PTC 1-2.
Other intervention name(s): vecuronium bromide; vecuronium bromide
Intervention MeSH terms: Bromides; Vecuronium Bromide
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Other
Keywords: neuromuscular blockade; sugammadex