Intravenous Sedation III Flashcards
Types of intravenous sedating agents?
Diazepam - historical
Midazolam - quick onset action, rapid metabolism and excretion
- Additional drugs - multidrug sedation (Propofol, opiates)
What is the reversal agent of midazolam?
Flumazanil
Midazolam for injections - what does it contain?
Clear, colourless isotonic (= not painful on injection) solution containing:
- Sodium chloride
- Hydrochloric acid
- Sodium hydroxide in water for injection
Midazolam pH?
3.3
Lipid soluble at physiological pH
How does midazolam (benzodiazepine) work?
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
What is GABA? Types of GABA?
Inhibitory neurotransmitter
GABA - A: Modulated by other receptors: benzodiazepines, barbiturates, some steroids, alcohol
GABA -: Skeletal muscle role
What are the effects of GABA?
Opening of receptor channels (Cl influx):
- Anxiolytic effect
- Hypnotic sedative
- Anticonvulsive
- Amnestic effect
- Muscular relaxation
Midazolam elimination half life?
1-2.8hrs
Onset of action of midazolam when IV, IM, oral, nasal, rectal?
IV 3 mins IM 5 mins Oral 15 mins Nasal 15 mins Rectal 15 mins
What increases the midazolam availability/half life?
Age (increased elderly)
Sepsis
Poor renal function
Additional effects of midazolam?
Decrease ventilatory responses to CO2 - important if COPD
Decrease mean arterial pressure
Reduction of cerebral blood flow
Midazolam contraindications?
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)
When should you take extra care when using midazolam?
Midazolam can be a respiratory depressant BZP use Opiates Alcohol abuse history Other sedatives Social drugs
Signs of midazolam overdose?
Over sedation Confusion Impaired coordination Diminished reflexes Decreasing vital signs/O2 sats
What to do when a pt overdoses on midazolam?
Stop midazolam
Oxygen
Reversal - Flumazanil 200ug in initial dose
Flumazenil features?
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
Patient preparation for intravenous sedation?
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
What to do when you insert a cannula into an artery and NOT a vein?
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
Types of embolism?
Thromboembolism
Cannula embolism
Air embolism
Adverse incidents when using cannulas for IV sedation?
Puncture of artery
Damage to nerve, tendon, ligament, limb
Blockage of cannula
Needlestick injury
What to monitor when the pt is having sedation?
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
When to consider oxygen supplementation?
Epilepsy IHD Previous stroke Heart failure Anaemia/sickle cell trait
How should the operator act regarding pts undergoing IV sedation?
Behaviour to induce confidence/relaxation
Quieten voices
Appropriate language
ALWAYS have operator and additional trained person in room - record this in notes
How to prepare IV drugs?
NPSA guidelines on preparation and administration of drugs for injection
- Sterility
- Labelling
- Disposal
- Recording
LA when pt sedated?
Give LA as well as midazolam has no analgesic properties
Midazolam titration/administration?
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
Complications of IV sedation?
Falling sats Under sedated Over sedated Venepuncture related: - Failed - Bruising - Extravasation
IV sedation recovery and discharge?
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
Post op instructions after IV sedation?
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
IV sedation note recording?
Log of all medicines used
Dispose of unused midazolam properly and witnessed
Record any flumazanil use - check drug exp. dates
