Intravenous Sedation III

Question 1

Types of intravenous sedating agents?

Answer 1

Diazepam - historical
Midazolam - quick onset action, rapid metabolism and excretion
- Additional drugs - multidrug sedation (Propofol, opiates)

Question 2

What is the reversal agent of midazolam?

Answer 2

Flumazanil

Question 3

Midazolam for injections - what does it contain?

Answer 3

Clear, colourless isotonic (= not painful on injection) solution containing:

• Sodium chloride
• Hydrochloric acid
• Sodium hydroxide in water for injection

Question 4

Midazolam pH?

Answer 4

3.3

Lipid soluble at physiological pH

Question 5

How does midazolam (benzodiazepine) work?

Answer 5

Benzodiazepines enhance the inhibitory action of GABA in the CNS
BZD potentiate GABA by increasing the flux of Cl ions into the cell = decrease ability of the cell to initiate an action potential

Question 6

What is GABA? Types of GABA?

Answer 6

Inhibitory neurotransmitter
GABA - A: Modulated by other receptors: benzodiazepines, barbiturates, some steroids, alcohol
GABA -: Skeletal muscle role

Question 7

What are the effects of GABA?

Answer 7

Opening of receptor channels (Cl influx):

• Anxiolytic effect
• Hypnotic sedative
• Anticonvulsive
• Amnestic effect
• Muscular relaxation

Question 8

Midazolam elimination half life?

Answer 8

1-2.8hrs

Question 9

Onset of action of midazolam when IV, IM, oral, nasal, rectal?

Answer 9

IV 3 mins
IM 5 mins
Oral 15 mins
Nasal 15 mins
Rectal 15 mins

Question 10

What increases the midazolam availability/half life?

Answer 10

Age (increased elderly)
Sepsis
Poor renal function

Question 11

Additional effects of midazolam?

Answer 11

Decrease ventilatory responses to CO2 - important if COPD
Decrease mean arterial pressure
Reduction of cerebral blood flow

Question 12

Midazolam contraindications?

Answer 12

Hypersensitivity to BZP
Myasthenia gravis
Shock or vial sign depression
Acute narrow angle glaucoma - open angle glaucoma with appropriate Rx - ask treating physician (potential for blindness)

Question 13

When should you take extra care when using midazolam?

Answer 13

Midazolam can be a respiratory depressant
BZP use
Opiates
Alcohol abuse history 
Other sedatives
Social drugs

Question 14

Signs of midazolam overdose?

Answer 14

Over sedation
Confusion
Impaired coordination
Diminished reflexes
Decreasing vital signs/O2 sats

Question 15

What to do when a pt overdoses on midazolam?

Answer 15

Stop midazolam
Oxygen
Reversal - Flumazanil 200ug in initial dose

Question 16

Flumazenil features?

Answer 16

Dose 200-600ug IV
Competitive inhibitor of benzodiazepines (BZP)
Elimination halflife 53 mins = potential for re-sedation due to differences in half life if reversal agent used

Question 17

Patient preparation for intravenous sedation?

Answer 17

Pre-assessed: Baseline observations e.g. BP
MH inc allergies and drugs
ASA assessment
Written consent - treatment checked
Escort/transport/childcare etc checked
No need to starve pt for IV midazolam but some dentists do ask pt to starve
CCDH Policy = 2 hrs starve prior to IV midazolam sedation

Question 18

What to do when you insert a cannula into an artery and NOT a vein?

Answer 18

Realise you are in artery with a cannula before drug admin: Remove cannula and apply pressure
Notice it post drug admin = leave cannula in place and contact local vascular surgeons urgently = Medical emergency, keep pt warm and monitor them

Look out for transfixation, haematoma, embolism

Question 19

Types of embolism?

Answer 19

Thromboembolism
Cannula embolism
Air embolism

Question 20

Adverse incidents when using cannulas for IV sedation?

Answer 20

Puncture of artery
Damage to nerve, tendon, ligament, limb
Blockage of cannula
Needlestick injury

Question 21

What to monitor when the pt is having sedation?

Answer 21

BP, HR, O2 saturation
BP required pre and post tx and can be continuously monitored
O2 saturation required throughout
Observation of pt - vital signs:
- Body temp
- Pulse rate
- Resp rate

Question 22

When to consider oxygen supplementation?

Answer 22

Epilepsy
IHD
Previous stroke
Heart failure
Anaemia/sickle cell trait

Question 23

How should the operator act regarding pts undergoing IV sedation?

Answer 23

Behaviour to induce confidence/relaxation
Quieten voices
Appropriate language
ALWAYS have operator and additional trained person in room - record this in notes

Question 24

How to prepare IV drugs?

Answer 24

NPSA guidelines on preparation and administration of drugs for injection

• Sterility
• Labelling
• Disposal
• Recording

Question 25

LA when pt sedated?

Answer 25

Give LA as well as midazolam has no analgesic properties

Question 26

Midazolam titration/administration?

Answer 26

Slow IV administration of 2mg
Wait 90 secs and reassess sedation 
1mg 
Wait 90 secs and assess
1mg and assess until desired sedation achieved 

1st 20 mins = most powerful so get worst done then
Another 30 mins possible - may require top ups
Realistic tx in time: dose range 2-10mg usual

Question 27

Complications of IV sedation?

Answer 27

Falling sats
Under sedated
Over sedated
Venepuncture related:
- Failed
- Bruising
- Extravasation

Question 28

IV sedation recovery and discharge?

Answer 28

Monitor whilst recovering
Keep 1 hr after last IV dose of midazolam
Written and verbal post op instructions to escort
Rhomberg
Steady on feet/walk unaided
Ring pt the next day and go over everything
Person taking them home is happy with the pt’s condition

Question 29

Post op instructions after IV sedation?

Answer 29

For 24hrs:
No driving/operating machinery inc. cooking and ironing
No alcohol/sedative drugs
No legal responsibilities inc. signing legal documents, looking after children, attending work
Pt not to be left alone

Question 30

IV sedation note recording?

Answer 30

Log of all medicines used
Dispose of unused midazolam properly and witnessed
Record any flumazanil use - check drug exp. dates