Neuromuscular Blockade and Sedation

Assessment Tools:

• Critical Care Pain Observation Tool (CPOT) (0-8)
• Behaviour Pain Scale (BPS)
• Sedation is Richmond Agitation Sedation Scale (RASS) or Sedation-Agitation Scale (SAS)

Sedation Agents:

• Propofol:
  • Rapid onset (1-2 minutes)
  • Short duration (3-5 minutes).
  • Avoid prolonged infusions greater than 50 mcg/kg/min.
  • Monitor BP, triglycerides, adjust lipid calories
  • Monitor for propofol infusion syndrome: metabolic acidosis, hemodynamic instability, cardiac failure, arrhythmias, cardiac arrest, rhabdomyolysis, hypertriglyceridemia, kidney failure, and hyperkalemia
    • Usually for infusion rates higher than 75-83 mg/kg/min for more than 48 hours.
  • Causes respiratory depression, must be intubated.
• Dexmedetomidine: Dexmedetomidine is a highly selective α2-adrenergic receptor agonist. It has effects similar to other α2-adrenergic receptor agonists (think clonidine) and is used as a sedative
  • Rapid onset (5-15 minutes)
  • Short duration (2-hour half-life)
  • Can cause bradycardia and hypotension (again think clonidine). However, initial titrations can cause a vasoconstrictive rise in BP (temporary and usually not clinically significant). It can also have EKG effects.
  • Can affect blood sugar.
  • Can be used to decrease intracranial pressure.
  • Low incidence of delirium.
  • Does not cause respiratory depression.
  • Dexmedetomidine can have withdrawal symptoms if used long term (1-2 days). Rebound increase in heart rate and blood pressure and increased anxiety unless titrated.
  • Adverse effects are mostly additive effects with other sedatives or medications that lower heart rate and blood pressure.
• Ketamine –
  • Analgesic and sedative properties.
  • Risk of delirium.
  • Adverse effects: hypertension, tachycardia, and delirium.
  • No respiratory depression
• Delirium
  • CAM-ICU Scale – Confusion Assessment Scale for ICU
  • ICDSC: Intensive Care Delirium Screening Checklist
  • Best course is prevention, including minimizing BZD doses, opioids, and anticholenergic medications.
  • Can treat with: haloperidol, quetiapine, olanzapine, risperidone, ziprasidone.  Olanzapine and risperidone have the lowest risk of QTc prolongation.

Neuromuscular Blockade

• Never use a neuromuscular blocker on someone who is not sedated and doesn’t have analgesia.
• Drugs/Electrolytes that potentiate block: corticosteroids, aminoglycosides, clindamycin, tetracyclines, polymixin, calcium channel blockers, Type 1a antiarrhythmics, furosemide, lithium, hypocalcemia, hypermagnesemia, hypokalemia
• Drugs/Electrolytes that antagonize block: aminophylline, theophylline, carbamazepine, phenytoin, hyperkalemia, hypercalcemia
• Succinylcholine and atracurium cause direct mast cell release.  Pancuronium, rocuronium, and vecuronium cause the least.  This is not anaphylaxis.
• When neuromuscular blockers are used in combination with steroids, it increases the risk of acute quadriplegic myopathy syndrome.
• Reverse non-depolarizing agents with neostigmine or edrophonium (acetylcholinesterase inhibitors). DO NOT USE THESE WITH succinylcholine.  They make succ induced paralysis worse.