midazolam

see also:

• benzodiazepines
• anticonvulsants
• sedatives, hypnotics and anxiolytics
• induction agents

• RCH - seizures - safety issues and how to help (pdf)
• RCH - intranasal midazolam (pdf)
• RCH - buccal midazolam (pdf)

• short-acting water soluble benzodiazepine which can thus be used intranasally, orally as well as iv, im.
• 95% prot.bound; T½=2hrs; Vd = 1.1L/kg; Clear. = 6.6ml/min/kg;

• see seizures
• paediatric:
  • intranasal 0.2mg/kg (max. 10mg)
  • buccal 0.5mg/kg (max. 10mg)
  • iv/im 0.15 mg/kg
• adult:
  • iv/im 0.15 mg/kg

• adults:
  • 1-2mg iv bolus
  • usually combined with a short acting opiate such as boluses of fentanyl 0.5-1mcg/kg
• beware respiratory depression, particularly with iv doses in children, the elderly and those with poor respiratory or CNS function.

• induction:
  • see induction agents
• maintenance of GA in an intubated patient:
  • usually an infusion of midazolam combined with morphine
    • make up infusion to concentration of 1mg/ml of each of midazolam & morphine by:
      • 100ml NS, withdraw 10ml and add 120mg of morphine and 120mg midazolam
      • run at 0.02-0.08 ml/kg/hr

• Hypotension
• Respiratory depression / Apnoea
• CVS effects usually minimal but may have arrhythmias
• Confusion
• Laryngospasm, bronchospasm, cough, hiccoughs, hives
• Children may experience paradoxical excitement

• Myasthenia gravis
• Known sensitivity to benzodiazepines (rare)
• Acute narrow angle glaucoma
• For procedural sedation - known airway problems/difficulties (e.g. previous airway surgery, previous difficulties with anaesthetic management)
• Acute and chronic hypoventilation (e.g. respiratory disease with severe hypoxia or any hypercapnia, obstructive sleep apnoea)
• For procedural sedation age < 1 year is a contraindication due to increased risk of airway complications.
  • procedures may be more safely performed under general anaesthetic in theatre

• must be administered with extreme caution in the presence of:
  • Hypotension;
  • Respiratory depression (unventilated patients)
  • Hypovolaemia
• Care is needed during sedation as unconsciousness can occur in some people with relatively small doses.
• Some depression of cardiovascular function occurs, especially with higher doses or patients with reduced reserve
• dosage should be reduced in patients with liver disease
• Midazolam should be used in conjunction with narcotic analgesics as it does not have analgesic properties.
• extravasation should be avoided
• Intravenous Midazolam should only be used in a setting where there is equipment for continuous monitoring of respiratory and cardiac function.
• In children the use of IV or IM Midazolam should be in the resuscitation area only.
• Midazolam can enhance the central sedative effects of neuroleptics, tranquillisers, antidepressants, analgesics and anaesthetics.
• Ideally the level of sedation should be such that the patient is calm and responsive, ie. to external stimuli. Sedation levels and drug administration rates should be assessed frequently to ‘maintain contact’ with the patient
• Administration of midazolam for agitation is a contraindication to placing patients in seclusion until effects have worn off
• Patient consent for procedures is not valid after the administration of Midazolam

• supportive care with protection of airways and respiration
• if patient has not been on benzodiazepines prior, then consider use of benzodiazepine antagonists such as:
  • flumazenil
    • Paed 5 mcg/kg per dose titrated to a total dose of 40mcg/kg
    • Adult 300 – 600 mcg
    • BUT MAY PRECIPITATE SEIZURES IN THOSE WITH DEPENDENCY OR WITH POLYPHARMACY OVERDOSES