IV Sedation

Question 1

What are the ideal characteristics of an IV sedation agent?

Answer 1

Anxiolysis
Sedation (side-effect)
Ease of administration
Non-irritant
Quick onset
Quick recovery
No side effects
Low cost

Question 1

What is the action of benzodiazepines?

Answer 1

Acts on receptors in CNS to enhance effect of GABA)
–Prolongs time for receptor repolarisation
Mimics effects of glycine on receptors
All active BZD’s have benzine ring allowing attachment to receptors in the nervous system

Question 2

What are the effects of sedative agents?

Answer 2

Respiratory Depression
–CNS depression and muscle relaxation
–Decreases cerebral response to increases CO2
–Synergistic relationship with other CNS depressants which enhance their effects
–Increased respiratory depression in already compromised patients
Cardiovascular
–Decreased BP by muscle relaxation decreasing vascular resistance
–Increased HR due baroreceptor reflex compensating BP fall

Question 3

What side effects can IV sedation have?
Drug interactions?
Tolerance?

Answer 3

Drug interactions
–any other CNS depressants
–Erythromycin
–antihistamines
Tolerance
–in patients with a history of drugs, can find their tolerance is higher and they are more likely to be unable to be sedated

Question 4

What type of drug is Midazolam?

Answer 4

Imidazobenzodiazepine

Question 5

What is the elimination half life of Midazolam?

Answer 5

90-150 minutes

Question 6

Where is Midazolam metabolised?

Answer 6

Liver
Extra-hepatic metabolism in bowel so less affected by liver disease than some other drugs

Question 7

Where do you place cannula for IV sedation?

Answer 7

Dorsum of hand
Antecubital fossa

Question 8

How do you administer Midazolam?
What increments?

Answer 8

Through a cannula intravenously
Increments;
-initial 2mg bolus
-1mg increments every 60 seconds until suitable level of sedation

Question 9

What is the end point of sedation?

Answer 9

Slurring and slowing of speech
Relaxed
Delayed response to commands
Willingness to accept treatment
Verrill’s sign-ptosis (eyelids drooping)
Eve’ sign- loss of motor coordination
Should not lose verbal communication

Question 10

What is taken before sedation at the assessment appointment?

Answer 10

Pre-op pulse and blood pressure
Oxygen saturation
BMI

Question 11

What is monitored throughout the IV sedation procedure?
Why?

Answer 11

Pulse oximeter
Blood pressure- taken at 5-10 minute intervals
This acts as an early warning system, allows intervention before emergency develops

Question 12

What type of drug is flumazenil?

Answer 12

Benzodiazepine antagonist

Question 13

What is the half life of flumazenil?

Answer 13

50 mins

Question 14

What is the risk of using flumazenil to reverse midazolam?

Answer 14

Risk of re-sedation
When flumazenil wears off and midazolam is still lasting

Question 15

What must be carried out before sedation treatment?

Answer 15

A separate appointment for sedation assessment

Question 16

What are pharmacodynamic interactions?
What are the predictable ones for midzaolam?

Answer 16

Interactions between drugs which have similar or antagonistic pharmacological effects or side effects
Predicable ones;
-Antidepressants
-Antihypertensives

Question 17

What are pharmacokinetic interactions?

Answer 17

One drug alters the absorption, distribution, metabolism or excretion of another, thereby increasing or reducing the amount of drug available to produce its pharmacological effects
Not predictable