1. Intravenous Sedation Flashcards
(34 cards)
What is the mode of action of a benzodiazepine drug ?
Acts on receptors in CNS to enhance effect of GABA and to mimic effect of glycine on receptors - slows repolarisation time.
What is glycine ?
Similar inhibitory neurotransmitter that works on brainstem and spinal cord.
What allows benzodiazepines to attach to receptors in NS ?
Benzene ring.
What is the respiratory effects of benzodiazepines ?
Respiratory depression.
Why does benzodiazepines cause respiratory depression ?
CNS depression causing muscle relaxation.
Decreases cerebral response to increasing CO2 i.e. causing inhalation of air.
What is the cardiovascular effects of benzodiazepines ?
Reduced BP by muscle relaxation decreasing vascular resistance.
Increased HR due to baroreceptor reflex compensating for BP fall.
What are the three main drug interactions associated with benzodiazepines ?
Any other CNS depressants.
Erythromycin.
Antihistamines.
4 main side effects of benzodiazepines ?
Tolerance.
Dependence.
Drug interactions.
Sexual fantasies.
Why is diazepam no longer used ?
Insoluble in water, suspension in propylene glycol causing lots of pain on injection.
Elimination half life long & unpredictable.
Slower onset.
Risk of rebound sedation.
Longer recovery.
Unpredictable.
What is the preparation of midazolam used ?
5mg/5ml (pH 3.5).
What is the elimination half life of midazolam ?
90-150 minutes.
Where is midazolam metabolised ?
Liver.
Extra hepatic metabolism in bowel - less affected by liver disease.
What are the benefits of midazolam which means it is ‘gold standard’ sedation drug of choice vs. diazepam ?
Painless.
Quicker onset.
Quicker recovery.
More reliable.
Cheaper.
What cannula should be used for IV sedation ?
In-dwelling cannula (Teflon) - rarely blocks and more secure.
Why should a butterfly cannula not be used ?
Clots and obstructs.
Easily dislodged.
What are the two cannulation sites ?
Dorsum of the hand - metacarpal veins.
Antecubital fossa.
What is the function of flumazenil ?
Reversal agent - antagonist of benzodiazepines.
How often should blood pressure be checked throughout treatment ?
Every 5-10 mins.
In what regime should midazolam be administered ?
1mg/1ml in 5mg/5ml vial.
2mg bolus.
1mg increments every 60 secs until appropriate response of the patient.
How to check for anaesthesia ?
Slurring and slowing of speech.
Relaxed.
Delayed response to commands.
Willingness to accept treatment.
Verrill’s sign-ptosis.
Eve’s sign - shut eyes and touch nose i.e. loss of motor coordination.
Maximum dose of midazolam in dental setting ?
7.5mg.
How long will sedation typically last ?
45 mins.
When can a patient be discharged and allowed to go home ?
60 minutes post-last increment.
Can walk unaided.
What are the stages if a patient falls into respiratory depression ?
- Head tilt, chin lift, jaw thrust.
- Oxygen via nasal cannuale (2l/min).
- Oxygen via Hudson mask (15l/min).
- Flumazenil.
