Optimal Dose of Succinylcholine and Rocuronium for Electroconvulsive Therapy (ECT)

• Optimal dose of neuromuscular blocking agent during ECT [ Time Frame: Up to six weeks following inclusion ] [ Designated as safety issue: Yes ]
  The optimal dose of muscle neuromuscular blocking is defined as the lowest dose of either compound that predicts 'acceptable' control of muscle strength during ECT. Assessment of the primary end point is based on a dichotomous scale 'acceptable' and 'not acceptable' control of muscle strength during ECT, and the two assessors will be blinded to the dose of neuromuscular blocking agent.
  
  
• Compound specific differences in time to recovery from neuromuscular blockade [ Time Frame: Up to six weeks following inclusion ] [ Designated as safety issue: Yes ]
  The investigators would like to define the compound specific differences in time to recovery from neuromuscular blockade - i.e., recovery of spontaneous breathing and recovery of the twitch height to baseline.
  
  

• Differences in seizure duration between compounds [ Time Frame: Up to six weeks following inclusion ] [ Designated as safety issue: Yes ]
  Observational reports suggest that differences in seizure duration might exist depending on the neuromuscular blocking agents used to accomplish muscle strength control during ECT.
  
  

Patients, who consent to participate in the study, will randomly receive either succinylcholine or rocuronium by utilizing the Dixon's up and down technique. For patient safety, the first dose of either agent will be defined by the anesthesiologist providing care, and subsequent doses will be incrementally increased or decreased by 10% based on the assessment of a psychiatrist blinded to dose, who uses a dichotomous scale to assess the quality of the ECT (acceptable and not acceptable). The investigators will switch to the second compound as soon as the patient has received one neuromuscular blocking agent dose that resulted in 'acceptable muscle relaxation', and another dose that resulted in 'unacceptable' conditions'.

Acceleromyography will be used for monitoring neuromuscular transmission. Following induction of general anesthesia, the TOF-Watch SX will be calibrated (mode 1, 50 mA), and train-of-four (TOF) stimulation (every 15 seconds) will be initiated and maintained until recovery of the T1 to 100% baseline. Non-invasive blood pressure, heart rate, peripheral oxygen saturation (SpO2), and time to recovery of spontaneous breathing will be measured during the procedure. In addition the investigators will measure stimulation parameters used to initiate ECT, as well as the duration of seizure as well as the entire procedure time.