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BDS4 Sedation > Intravenous Sedation > Flashcards

Intravenous Sedation Flashcards

1
Q

What is the action of benzodiazepines?

A
  • 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
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2
Q

What are the ideal properties of an IV sedation agent?

A
  • anxiolysis
    • reduces patient anxiety
  • sedation
    • usually side effect
  • ease of administration
  • non-irritant
  • quick onset
  • quick recovery
  • no side effects
    • unless useful
      • sedation
      • amnesia
  • amnesia
    • useful side effect
  • low cost
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3
Q

What part of the benzodiazepine molecule attaches to receptors?

A

benzene ring

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4
Q

How does intravenous sedation cause respiratory depression?

A
  • 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
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5
Q

What affect does intravenous sedation have on the cardiovascular system?

A
  • reduced blood pressure
    • muscle relaxation
    • decreased vascular resistance
  • increased heart rate
    • baroreceptor reflex
      • compensates for blood pressure fall
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6
Q

What are the possible side effects for intravenous sedation?

A
  • 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
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7
Q

Describe diazepam as a sedation agent

A
  • first widely used benzodiazepine
  • insoluble in water so comes in preparation
    • Valium
      • propylene glycol
      • 5mg/ml
    • Diazemuls
      • soya bean oil
      • 5mg/ml
  • pain on injection
    • propylene glycol
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8
Q

What are the elimination and redistribution half-lives of diazepam and what are the metabolites produced?

A
  • elimination half life
    • 43 +/- 13 hours
  • redistribution half life
    • 40 minites
  • metabolites
    • desmethyldiazepam
      • 73 hours
    • oxazepam
      • 7 hours
  • risk of rebound sedation
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9
Q

What dose of diazepam was used for IV sedation and why is it no longer used?

A
  • dose
    • 0.1-0.2mg/kg
  • long recovery period
  • unpredictable
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10
Q

Describe midazolam as a sedation agent

A
  • Hypnovel
    • trade name
    • current gold standard
  • water soluble imadazobenzodiazepine
    • pH <4
  • lipid soluble at physiologic pH
    • allows crossing of BBB
  • painless on injection
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11
Q

What is the concentration of one preparation of midazolam?

A

5mg/5ml

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12
Q

What is the elimination half life of midazolam?

A

90-150 minutes

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13
Q

Where is midazolam metabolised?

A
  • the liver
  • extra-hepatic metabolism in the bowel
    • less affected by liver disease
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14
Q

Who must be present during sedation of a patient?

A
  • 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
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15
Q

What kind of cannula should be used for intravenous sedation and why?

A
  • 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
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16
Q

Why should butterfly cannulas not be used?

A
  • made of metal
  • clots and obstructs easily
  • easily dislodges
  • only used for taking blood
17
Q

Why is the dorsum of the had a good cannulation site and what are the potential disadvantages?

A
  • accessible
  • superficial and visible
  • poorly tethered vessels
  • affected by peripheral vasoconstriction
18
Q

What vessels are cannulated in the antecubital fossa and what are the considerations associated with this site?

A
  • 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
19
Q

What can be done to make cannulation easier for patients with anxiety surrounding needles?

A
  • topical anaesthetic applied to skin
    • not commonly done
    • patient puts on before they come in
    • fear of needles, not cannulation
20
Q

What must be carried out before commencing IV sedation?

A
  • 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
21
Q

What must be monitored during IV sedation and why?

A
  • pulse oximeter
  • NIBP (non-invasive blood pressure)
    • every 5-10 minutes
  • acts as early warning system
    • intervention before emergency develops
    • minimises risk
22
Q

What must be available in case of emergency during IV sedation?

A
  • flumazenil
    • available before sedation starts
  • means of ventilation
    • if patient cannot maintain airway
  • medical emergencies bag
23
Q

How is midazolam administered for IV sedation?

A
  • 2mg bolus initially
  • followed by 1mg increments
    • every 60 seconds
    • until suitable level of sedation achieved
24
Q

What is the maximum dose of midazolam?

A
  • 7.5mg
    • 5mg is commonly sufficient
25
Q

How can it be determined that a suitable level of sedation has been achieved?

A
  • slurring and slowing of speech
  • relaxed
  • delayed response to commands
  • willingness to accept treatment
  • Verrill’s sign (ptosis_
  • EVe’s sign (loss of motor coordination)
26
Q

What happens if the maximum dose of midazolam is administered and the patient is not adequately sedated?

A
  • proceed with treatment if patient comfortable
  • abandon treatment
    • find alternative method
27
Q

How much sedation does midazolam provide?

A

30-45 minutes

28
Q

Once treatment is finished, what does recovery after IV sedation involve?

A
  • escort with patient
    • given post op instructions
  • begins 60 minutes after last increment
  • remove cannula
    • poses infection risk
  • patient must walk unaided
29
Q

What is the most common medical emergency associated with IV sedation?

A

respiratory depression

30
Q

How should respiratory depression be managed during IV sedation

A
  • talk, shake, hurt
    • try to rouse the patient
    • stop treatment and encourage deep breaths
  • head tilt, chin lift, jaw thrust
    • improve airway
    • must see chest rising
  • oxygen delivery
    • 2ml a minute via nasal cannulae
      • use initially and continue treatment
    • 5ml a minute via Hudson mask
      • may have to stop treatment
  • flumazenil
    • deliver if oxygen not helping
  • ambu bag
    • for all other medical emergencies
31
Q

What does the standard preparation of flumazenil contain?

A

500ug in 5ml

32
Q

What dose of flumazenil should me administered?

A
  • 200ug initially
  • 100ug every 60 seconds until response seen
33
Q

What are the risks of flumazenil?

A
  • risk of resedation
    • half life of 50 minutes
    • shorter than midazolam
    • must monitor patient for longer
      • ensure drugs have been metabolised
  • anaphylaxis
    • do not administer flumazenil
      • may be a BDZ allergy

BDS4 Sedation (9 decks)

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