Intravenous Sedation Flashcards
What is the action of benzodiazepines?
- acts on receptors in the CNS
- cerebral cortex and motor circuits
- enhances effect of GABA
- gamma-amino butyric acid
- inhibitory neurotransmitter
- prolongs time for receptor depolarisation
- mimics effect of glycine on receptors
- brainstem and spinal cord
What are the ideal properties of an IV sedation agent?
- anxiolysis
- reduces patient anxiety
- sedation
- usually side effect
- ease of administration
- non-irritant
- quick onset
- quick recovery
- no side effects
- unless useful
- sedation
- amnesia
- unless useful
- amnesia
- useful side effect
- low cost
What part of the benzodiazepine molecule attaches to receptors?
benzene ring
How does intravenous sedation cause respiratory depression?
- CNS depression and muscle relaxation
- decreased cerebral response to increased carbon dioxide
- synergistic relationship with other CNS depressants
- increased respiratory depression in already compromised patients
What affect does intravenous sedation have on the cardiovascular system?
- reduced blood pressure
- muscle relaxation
- decreased vascular resistance
- increased heart rate
- baroreceptor reflex
- compensates for blood pressure fall
- baroreceptor reflex
What are the possible side effects for intravenous sedation?
- drug interactions
-any other CNS depressant- erythromycin
- antihistamines
- tolerance and dependence
- not just from one IV sedation session
- BDZs abuse
- diazepam prescription limited to 2 weeks
- may not be able to give enough sedative
- sexual fantasies
- affects both males and females
- increased chance with higher doses
- seditionist should never be alone with pt
Describe diazepam as a sedation agent
- first widely used benzodiazepine
- insoluble in water so comes in preparation
- Valium
- propylene glycol
- 5mg/ml
- Diazemuls
- soya bean oil
- 5mg/ml
- Valium
- pain on injection
- propylene glycol
What are the elimination and redistribution half-lives of diazepam and what are the metabolites produced?
- elimination half life
- 43 +/- 13 hours
- redistribution half life
- 40 minites
- metabolites
- desmethyldiazepam
- 73 hours
- oxazepam
- 7 hours
- desmethyldiazepam
- risk of rebound sedation
What dose of diazepam was used for IV sedation and why is it no longer used?
- dose
- 0.1-0.2mg/kg
- long recovery period
- unpredictable
Describe midazolam as a sedation agent
- Hypnovel
- trade name
- current gold standard
- water soluble imadazobenzodiazepine
- pH <4
- lipid soluble at physiologic pH
- allows crossing of BBB
- painless on injection
What is the concentration of one preparation of midazolam?
5mg/5ml
What is the elimination half life of midazolam?
90-150 minutes
Where is midazolam metabolised?
- the liver
- extra-hepatic metabolism in the bowel
- less affected by liver disease
Who must be present during sedation of a patient?
- operator/sedationist
- commonly dentist trained in sedation
- cannot leave the surgery
- second sedation trained staff
- usually dental nurse
- cannot leave the surgery
- runner
- recovery nurse
- separate recovery area
What kind of cannula should be used for intravenous sedation and why?
- in-dwelling cannula
- stays in for duration of treatment
- secure
- teflon
- part that remains in vein
- rarely blocks
- range of sizes
- may be required for an emergency
Why should butterfly cannulas not be used?
- made of metal
- clots and obstructs easily
- easily dislodges
- only used for taking blood
Why is the dorsum of the had a good cannulation site and what are the potential disadvantages?
- accessible
- superficial and visible
- poorly tethered vessels
- affected by peripheral vasoconstriction
What vessels are cannulated in the antecubital fossa and what are the considerations associated with this site?
- cephalic vein
- median basisilic vein
- keep lateral to bicep tendon
- brachial artery and median nerve
- less stable
- may have to remove some articles of clothing
What can be done to make cannulation easier for patients with anxiety surrounding needles?
- topical anaesthetic applied to skin
- not commonly done
- patient puts on before they come in
- fear of needles, not cannulation
What must be carried out before commencing IV sedation?
- pre-op pulse and blood pressure
- escort
- must stay in building
- does not have to be in the room
- travel arrangements
- preferable private car or taxi
- responsibilities
- arrangements made
- consent
- mandatory at separate visit
- reconfirmed on the day
What must be monitored during IV sedation and why?
- pulse oximeter
- NIBP (non-invasive blood pressure)
- every 5-10 minutes
- acts as early warning system
- intervention before emergency develops
- minimises risk
What must be available in case of emergency during IV sedation?
- flumazenil
- available before sedation starts
- means of ventilation
- if patient cannot maintain airway
- medical emergencies bag
How is midazolam administered for IV sedation?
- 2mg bolus initially
- followed by 1mg increments
- every 60 seconds
- until suitable level of sedation achieved
What is the maximum dose of midazolam?
- 7.5mg
- 5mg is commonly sufficient
