RS
- Respiratory depression and apnoea common
- Reduced response to hypercapnia
- Suppression of laryngeal and pharyngeal reflexes:
- Ideal drug to assist with placement of supraglottic airway devices
CVS
- Reduced systemic vascular resistance, cardiac output and blood pressure:
- Causes the most marked fall in BP of all induction agents
- Hypotension is dose dependent
- Vasodilatation possible mediated by nitric oxide release
- Can cause reflex tachycardia but more usually bradycardia
NS
- Sedation and anaesthesia:
- Dose dependent cortical depression
- Best endpoint is loss of verbal contact with the patient
- Excitatory movements:
- Seen in up to 10% of patients at induction
- Dystonic with choreiform elements
- Not epileptiform in nature
- Anti-epileptic:
- Has been used to terminate status epilepticus
- Reduced intracranial pressure, cerebral perfusion pressure and cerebral metabolic rate
GI
- Antiemetic effects (possibly D2-antagonist mediated)