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

Electroconvulsive therapy (ECT) is the transcutaneous application of small electrical stimuli to the brain to produce generalized seizures for the treatment of selected psychiatric disorders such as severe depression. The aim of ECT is to induce a therapeutic tonic seizure where the person loses consciousness and has convulsions. Patients need general anesthesia and neuromuscular blockade to treat pain and avoid excessive tonic clonic motor contraction that might be associated with compression fractures. Neuromuscular blocking drugs (NMBD) are, therefore, administered after induction of general anesthesia to induce neuromuscular blockade. Despite the importance of NMBDs to provide optimal conditions for ECT treatment, the optimal NMBD dose to achieve acceptable neuromuscular blockade without excessive or untoward effects has not previously been identified in any study and in a prospective randomized fashion. The aim of this study is, therefore, to identify the optimal NMBD dose of two commonly used neuromuscular blocking agents (succinylcholine and rocuronium) in order to optimize the muscle strength modulation during ECT that facilitates ECT with the minimal side effects.

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.

Eligibility Criteria:
Inclusion Criteria:

* Adult patients (age 18-80) scheduled for ECT treatment at the MGH

Exclusion Criteria:

* Contraindication to the use of neuromuscular blocking drugs (e.g. allergy, preexisting muscular disease, and history of malignant hyperthermia)
* Malnutrition, general weakness
* Neurological or neuromuscular disease, including paralysis
* Liver disease with liver function test 2x greater than upper normal limit
* Kidney disease with eGFR\<60
* Electrolyte abnormalities with values outside of the normal range
* Pregnancy
* Cardiac disease or abnormal EKG
* Medications that affect seizure threshold or blood pressure response
* Unwilling to participate in the study