IV induction agents Flashcards
Induction agents:
Propofol Benzodiazepines Barbituates Etomidate Ketamine
Opioids:
Morphine Fentanyl Codeine Tramadol Remifentanyl
Which drugs cause apnoea?
Propofol
Barbituates
(Etomidate has brief hyperventilation then brief apnoea)
Uses of propofol?
Induction, sedation and maintenance
Anti-emetic
Prevents seizures
Increases duration of midazolam (CY3A4)
Cardiac effects of propofol?
Reduced CO, SVR, BP and myocardial blood flow
What is propofol infusion syndrome?
Asystole Metabolic acidosis Rhabdomyolysis Fatty liver disease Hyperkalaemia
Use of barbiturates?
Cerebral protection
Seizure suppression
Anxiolysis
Respiratory effects of propofol?
Reduced tidal volume
Increased respiratory rate
Apnoea
Use of benzodiazepines?
Anticonvulsant (increases seizure threshold) Induction and sedation Midazolam = short for paeds Tamazepam and lorazepam = intermediate Diazepam = long
Cardiac effects of benzodiazepines?
Stable agent on the heart
Respiratory effects of benzodiazepines?
Decreased hypoxic and hypercapnic response
Use of ketamine?
Opiod sparing analgesia
Induction and sedation
Cardiac effects of ketamine?
Increased BP, CO, HR, symp and O2 consumption
Respiratory effects of ketamine?
RR interval maintained - good for paeds
No apnoea but potentially cause pulmonary hypertension
Contraindication for ketamine?
Do not use with a head trauma patient as the drug increases cerebral blood flow, cerebral oxygen consumption and intracranial pressure
(also cause increased muscle tone vivid dreams and hallucinations)
Cerebral effects of barbiturates?
Reduce cerebral O2 consumption, ICP and cerebral blood flow
Use of etomidate?
Similar to propofol
Good for kidney patients as liver metabolises to inactive metabolites
Cardiac effects of etomidate?
Increased BP and PR interval
Respiratory effects of etomidate?
Brief hyperventilation then brief apnoea
Decreased hypercapnic response
Use of dexmedetemide?
alpha-2 agonist
Opiod-sparing analgesic used for withdrawal
Used for neuromonitoring in brain/spine
Neuro-blockade, decreased CBF
Cardiac effects of dexmedetemide?
Bradycardia
Initial rise in BP
Decreased CO
Use of morphine?
Peri-operative analgesic
Vagal stimulation so causes constipation and biliary SM constriction
Pruritis and N+V
Cardiac effects of morphine?
Bradycardia
Respiratory effects of morphine?
Respiratory depression
Use of fentanyl?
80-100x potency of morphine
Peaks 5 minutes after IV
Less histamine
Codeine features:
Pro-drug
Risk to neonate if mother is a rapid metaboliser and is breast feeding
Use of tramadol?
50% potency of morphine also 5HT/NA-ergic
Safer cardiac/respiratory profile than morphine
Risk of serotonin syndrome
Use of remifentanyl?
Potent mu agonist with t1/2 of 3.7 minutes
Ultra-rapid onset and offset with end of infusion
Used for sedation in ICU, PCA in obstetrics and pain relief in surgery
Total IV anaesthesia (TIVA)
Which drugs are TIVA?
Propofol and remifentanyl
Benefits of TIVA?
Improved CV profile, reduced N+V and improved tube tolerance
