IV sedation

Question 1

Explain the action of benzodiazepines.

Answer 1

Acts on receptors in CNS to enhance effect of GABA (gamma-amino butyric acid) - prolongs time for receptor repolarisation
GABA = inhibitory neurotransmitter - lessens nerve cell’s ability to receive, create or send chemical messages

Question 2

What are the physiological respiratory effects of BZD’s?

Answer 2

Respiratory depression
- CNS depression and muscle relaxation
- Decreases cerebral response to increased CO2
- Increased respiratory depression in already compromised patients.

Question 3

What are the effects on BZD’s on the cardiovascular system?

Answer 3

Decreased BP by muscle relaxation decreasing vascular resistance
Increased HR due to baroreceptor reflex compensating for fall in BP

Question 4

What is the maximum amount of time a dentist can prescribe BZD’s?

Answer 4

2 weeks - to stop people getting addicted.

Question 5

What are some disadvantages of Diazepam?

Answer 5

Long elimination half-life - effects can last a long time
Risk of rebound sedation
Made up with propylene glycol which gives pain on injection
Long recovery
Unpredictable

Question 6

What are some benefits of midazolam?

Answer 6

Painless on injection
Rapid onset
More reliable
Quicker recovery

Question 7

What structures do you want to avoid in the antecubital fossa?

Answer 7

Brachial artery
Median nerve

Question 8

At what point can a patient be released after treatment under sedation with midazolam?

Answer 8

Minimum 60 minutes after last increment of drug

Question 9

What is the max. dose of midazolam that can be given to a patient for IV sedation?

Answer 9

7.5mg

Question 10

How to treat respiratory depression?

Answer 10

Talk, shake
Head tilt, chin lift, jaw thrust
If they can’t maintain airway, give them oesophageal airway
Give oxygen via bag valve mask
Flumazenil if midazolam OD

Question 11

What is the preparation of flumazenil?

Answer 11

0.5mg in 5ml

Question 12

What medication is most commonly used for IV sedation?

Answer 12

Midazolam

Question 13

Who should NOT get IV sedation?

Answer 13

Those with impaired liver and kidney function
Older people
Acute pulmonary insufficiency

Question 14

Where is midazolam metabolised?

Answer 14

In the liver

Question 15

Why is midazolam painless on injection?

Answer 15

Lipid soluble at physiologic pH allowing crossing of BBB

Question 16

What is the reversal drug for sedation?

Answer 16

Flumazenil

Question 17

What are the drug interactions of BZD’s?

Answer 17

Any other CNS depressantse.g. anti-depressants
Erythromycin
Antihistamines

Question 18

What is the elimination half-life of midazolam?

Answer 18

90-150 mins - short half-life so less working time
Less dangerous for pt. as they are sedated for less time

Question 19

What must be done prior to sedation on the day?

Answer 19

Sedation assessment - different day
Pre-op pulse
Pre-op blood pressure
Escort must stay in building
Travel arrangements confirmed
Consent - mandatory at assessment appt. but re-confirmed on the day

Question 20

What is the drug administration of midazolam?

Answer 20

2mg bolus then 1mg increments every 60seconds until patient is suitably sedated - everyone different with how much it takes

Question 21

What signs indicate a patient is suitably sedated and ready to start tx.?

Answer 21

Slurring and slowing of speech
Relaxed
Delayed response to commands
Willingness to accept treatment.

Verrill’s sign-ptosis - altered speech + blurred vision

Eve’s sign - touch finger to tip of nose - loss of motor co-ordination

Question 22

What is rough useful sedation time with midazolam?

Answer 22

Around 30-45 mins useful sedation

Question 23

What is flumazenil dosage?

Answer 23

0.2mg then 0.1mg increments every 60 seconds until response seen

Question 24

What risk is there with flumazenil and why?

Answer 24

Shorter half-life than midazolam - 50 minutes

Risk of re-sedation