IV Sedation Flashcards
What is the definition of sedation?
A technique in which a drug or drugs produces a state of depression of the CNS, enabling treatment to be carried out but verbal contact with the patient is maintained through the period of sedation.
The drugs and techniques used to provide conscious sedation for dental treatment carry a margin of safety wide enough to render unintended loss of consciousness unlikely.
What are the medical indications for sedation?
Think about conditions that are aggravated by stress of dental treatment, which may aggravate the medical condition.
Ischaemic heart disease
Hypertension
Asthma
Epilepsy
Parkinson’s disease
Spasticity disorders
Psychosomatic illness- gagging, persistent fainting, phobias.
What are the dental indications for sedation?
Difficult or unpleasant procedure- implants, XLA of third molar, orthodontic extractions in a young person.
What are the dental contraindications for sedation?
Procedure too long
Procedure too traumatic
Spreading infection- cannot get numb, compromised airway
What are the medical contraindications for sedation?
Severe or uncontrolled systemic Diases
Severe mental or physical disability- cannot communicate or unable to understand sedation
Severe psychiatric problems
Narcolepsy
Hypothyroidism
Intracranial pathology- brain trauma
COPD
Myasthenia Gravis
Hepatic insufficiency
Pregnancy and lactation
What are the social contraindications for sedation?
Unwilling
Unco=operative
Unaccompanied
Children- cannot give IV sedation to someone younger than 12
Very old
What is the ASA classification and why is it relevant for sedation?
American Association of Anaesthesiology.
We can only treat ASA 1 and 2 for sedation.
- ASA 1- a normal healthy individual.
- ASA 2- A patient with mild systemic disease.
3-6 cannot be sedated.
What type of drug is used for IV sedation?
Benzodiazepines- Midazolam.
What is the mechanism of action of Benzodiazepines?
Act on GABA receptors in the CNS to enhance the effects of GABA.
This reduces excitability of neurons within the CNS, resulting in impaired cognitive function.
Mimics effect of glycine on receptors.
How are Benzodiazepines able to bind to receptors in the CNS?
They have a benzene ring which allows them to bind to GABA receptors.
Describe the effects of sedation?
Respiratory depression- CNS depression and muscle relaxation.
- Decreases cerebral response to increased Co2
- Synergistic relationship with other CNS depressants- no one can be taking other CNS depressants.
- Increase respiratory depression in already compromised patients- no COPD.
Cardiovascular
- decreased blood pressure by decreasing vascular resistance
- Increase heart rate due to baroreceptor reflex compensating for BP fall.
What are some potentially unwanted side effects of benzodiazepines?
Drug interactions
- Any other CNS depressant
- Erythromycin
- Anithistamines
Tolerance- someone already taking benzodiazepines
Dependence- very addictive
Sexual fantasies
What are the properties of an ideal IV sedative?
Anxiolysis
Ease of administration
Non-irritant
Quick onset
Quick recovery
No side effects
Low cost
Amnesia?? Is this a good or a bad thing?
Why is midazolam painless to inject?
Soluble in water.
What is the dosage of midazolam used?
5mg/5ml.
pH 3.5
Give plus of 1mg and then 1mg every 60 seconds until adequate sedation achieved.
2-5 times more potent than diazepam
How is midazolam metabolised?
Metabolised in the liver- patients with hepatic insufficiency cannot be sedated with midazolam.
Extra-hepatic metabolism in the bowel.
Elimination half life is 90-150 minutes.
- less working time but it is safer because patients are sedated for less time.
Why is Midazolam preferred to Diazepam?
Diazepam is insoluble in water so needs to be mixed with propylene glycol- this can be painful.
Half life is much longer- 43 +/- 13 hours.
Risk of rebound sedation because of metabolites.
Unpredictable response and long recovery.
What is the reversal agent of midazolam?
Flumazenil- 500mcg in 5ml. Give 200mcg, then 100mcg every 60 seconds until a response is seen.
Very short half life compared to midazolam so there is a risk of re-sedation- 50 minutes.
How is the IV sedative given to the patient?
Through an in-dwelling cannula.
Must stay in during the whole treatment and ones the treatment has done incase emergency management is required.
What sites would you cannulate?
Veins in the dorsum of the hand- Basilica, metacarpal, dorsal venous arch.
Can also cannulate the antecubital fossa- basilic vein.
Why is cannulation of the antecubital fossa not ideal?
Brachial artery and median vein are close to the basilic vein.
Less stable is the patient starts moving around.
Why is the dorsum of the hand the gold standard cannulation site?
Accessible
Superficial and visible
But be aware that it is affected by peripheral vasoconstriction so may need to warm up hand.
If someone experiences respiratory depression during sedation, what would you do?
Stop what you’re doing.
Talk to them, shake them, head tilt, chin lift, jaw thrust.
Encourage them to take deep breathes- look for rise and fall of the chest.
2L/min oxygen through nasal cannula.
5L/min oxygen through a non-rebreathing mask.
If breathing still doesn’t improve- give flumazenil.
Have medical emergency equipment available to hand.
How much midazolam would you give the patient initially?
2mg bolus and then 1mg increments every 60 seconds until suitable level of sedation occurs.
Generally do not go any higher than 7.5mg.
