Special Care Flashcards
(118 cards)
1
Q
What are the four types of standard conscious sedation techniques?
A
- Inhalation sedation
- Intravenous sedation with midazolam by single route
- Oral sedation with single drug by a single route
- Intra nasal midazolam
2
Q
What drug/s is used in inhalation sedation?
A
Nitrous oxide and oxygen
3
Q
How is inhalation sedation delivered?
A
As a gas via a nose piece mask
4
Q
What two effects does nitrous oxide have on the body?
A
- Anxiolytic effects
- Analgesic effects
5
Q
Describe the 3-step procedure of administering nitrous oxide under inhalation sedation.
A
- Start with 100% oxygen for 1-2 minutes at flow rate of 5-6l/min
- Let patient settle, get used to mask, check for leaks, bag inflating properly
- Introduce the nitrous oxide in increments, each increment for a minute or two
6
Q
What is the usual amount of nitrous oxide (as a %) given to a patient going under inhalation sedation?
A
50%
7
Q
What is the maximum dose of nitrous oxide (as a %) given to a patient going under inhalation sedation?
A
70%
8
Q
What is the minimum dose of nitrous oxide (as a %) given to a patient going under inhalation sedation?
A
30%
9
Q
How fast is the onset of action of nitrous oxide?
A
Rapid (3-5 minutes)
10
Q
What equipment is required for inhalation sedation?
A
- Relative analgesia machine
- Gas cylinders or piped gases
- Scavenging system (removes excess gas to prevent being vented back into operating room)
11
Q
What are the 4 common indications for inhalation sedation?
A
- Mild anxiety
- Needle phobia
- Patient not suitable for IV/GA
- Straightforward dental treatment
12
Q
Why is it difficult to complete procedures on anterior teeth under inhalation sedation?
A
Because the mask may impede access to anterior teeth
13
Q
What are 8 contra-indications for inhalation sedation?
A
- Nasal blockages
2.COPD - Recent eye or ear suregry
- Mask intolerance
- Pregnancy
- Vitamin B12 deficiency
- Methotrexate interaction
- Chemotherapy interaction
14
Q
Why is vitamin B12 deficiency a contraindication for IHS?
A
This deficiency can be exacerbated by inhalation sedation and nitrous oxide inactivates vit B12 and may lead to irreversible neurological damage (myelopathy)
15
Q
What are signs of nitrous oxide overdose?
A
- headache
- nausea
- vomiting
16
Q
What is the management of nitrous oxide overdose?
A
- reduce dose
- oxygen flush
17
Q
What is diffusion hypoxia?
A
When nitrous oxide is discontinued, it leaves the blood more quickly than nitrogen from the air is absorbed, this can lead to dilution of oxygen in lungs which leads to hypoxia.
18
Q
Whenever IHS is complete, what should happen after nitrous oxide cessation? And why?
A
Administer 100% oxygen after cessation of nitorus oxide for 5 minutes to prevent diffusion hypoxia
19
Q
What drug is used in IV sedation?
A
Midazolam
20
Q
What is the reversal drug for midazolam?
A
Flumazenil
21
Q
What are the 6 common indications for IV sedation?
A
- Dental anxiety/phobia
- Medical conditions aggravated by stress (e.g. mild asthma, hypertension)
- Medical or behavioural conditions affecting the patient’s ability to co-operate (e.g. autism)
- Special care requirements
- Strong gag reflex
- Unpleasant procedure
22
Q
What are the 5 contraindications for IV sedation?
A
- Needle phobia
- Medical reasons
- Social reasons (e.g. no escort)
- Pregnancy
- Poor venous access
23
Q
What 8 pieces of equipment are required for an IV sedation procedure?
A
- Midazolam
- Flumazenil
- Labels for syringes
- Syringes
- Saline
- Pulse oximeter
- BP cuff and machine
- Tourniquet
24
Q
What is a tourniquet?
A
“ a device used to apply pressure to a limb or extremity in order to create ischaemia/stop blood flow.”
25
Name the three drugs required to carry out IV sedation, and their doses.
1. Midazolam (5ml ampoule, 1mg per ml)
2. Saline (2ml syringe)
3. Flumazenil (5ml ampoule, 100ug per ml)
26
When should flumazenil never be used during IV sedation?
If there is an identified benzodiazepine allergy (as flumazenil is a benzodiazepine)
27
What type of drug is midazolam?
Benzodiazepine
28
Why must patients legs be uncrossed when receiving IV sedation?
To avoid venous stagnation and to make patient more stable
29
What three veins are normally targeted in the arm, for IV sedation cannulation?
1. Median cubital vein
2. Cephalic vein
3. Basilic vein
30
What is the procedure for IV cannulation?
1. Swab site with 2% Chlorohexidine in 70% alcohol skin wipe and allow to dry for 30 seconds
2. Hold skin firmly and stretched
3. Cannula 22G with bevel up the way, at 10-15 degree angle to pierce the skin
4. Observe primary and secondary flashback before administering drug
31
What is primary flashback?
The appearance of blood within the cannula chamber
32
What is secondary flashback?
When withdrawing the clear plastic thumb guard of the cannula back a few mm’s, secodnary flashback (blood) will be seen in the cannula shaft.
33
What does flashback indicate?
That the cannula is in the vein lumen
34
What sensation should you warn the patient off prior to administering midazolam by IV sedation?
Warn patient they might feel a cold sensation up their arm, they shouldn’t feel pain or swelling.
35
If a patient feels pain radiating down their forearm after being administered midazolam by IV sedation, what does this indicate?
It’s a sign the cannula is not in the vein lumen, but accidentally entered an artery.
36
What are the 4 probelms with cannulation?
1. Difficulty locating vein
2. Veins collapse
3. Veins tissue ( needle has gone through side of vein)
4. Cannula kinks
37
What dose of midazolam should be administered at one time? How long should you wait between administration of doses?
1mg, 60 seconds
38
What is the maximum dose of midazolam that can be given?
10mg
39
What is Eve’s sign?
If a patient has their eyes closed and they’re trying to touch their nose with their finger, but struggling, this is a good indication they are well sedated.
40
What is Verrill’s sign? Why is it not the most reliable sign of sedation?
Where eyelids droop and cover half the eye. It may actually indicate oversedation.
41
What should be administered before and after administering midazolam?
Saline
42
Who has the shared responsibility of monitoring during sedation?
Sedation nurse and sedationist
43
What three things are monitored throughout sedation by monitoring machine?
SpO2, HR and BP
44
What 3 things can affect readings of pulse oximeter?
1.dark coloured nail polish/gel and acrylic nails
2. Finger tapping/playing with pulse oximeter
3. Cold hands/body
45
What does it mean if oxygen saturation drops below 90% during conscious sedation?
Inhibited respiratory or cardiovascular activity which can lead to cardiac arrest or brain damage
46
What are the three most common casues of oxygen saturation dropping below 90% during conscious sedation?
1. Respiratory depression
2. Breath-holding
3. Over-sedation
47
How do you manage oxygen saturation dropping below 90% during conscious sedation?
Immediate action, administer 100% oxygen via nasal cannula at 2-4 litres/min
48
How do you manage oxygen saturation dropping below 90% during conscious sedation, which is persistent and not corrected by breathing and giving oxgen ?
- Reverse sedation with flumazenil
- Bag and mask ventilation
- summon help and ambulance
49
If the pulse drops below 50 (bradycardia) during conscious sedation, what might this indicate?
Vasovagal attack
Vagal stimulation
Hypoxia
50
If the pulse rises above 120 (tachycardia) during conscious sedation, what might this indicate/result in?
Anxiety
Inadequate anaesthesia
Poor pain control
51
How long do you usually have to complete treatment under conscious sedation?
30-40 minutes
52
What is the action of benzodiazepines on respiratory system?
Cause some depression of protective reflexes and some degree of respiratory depression
53
How long must it be after the last increment of the sedation drug was given before the patient can be discharged?
At leats 1 hour
54
What is the Mallampati score used for?
To assess airways
55
What should be fully visible to allow for a mallampati score of 1?
The back of the mouth and the whole uvula
56
What allergy is important to check for before conscious sedation?
Benzodiazepine allergy
57
What does ASA classification system mean?
Assessment of Medical Fitness for Sedation
58
Define the ASA classification:
A patient without systemic disease; a normal healthy patient
ASA 1
59
Define the ASA classification:
A patient with moderate systemic disease; which limits activity but is not incapacitating, e.g. more severe asthma
ASA III
60
Define the ASA classification:
A patient with mild systemic disease; e.g. mild asthma
ASA II
61
Define “systolic” part of BP reading
Pressure in arteries when the heart beats
62
Define “diastolic” part of BP reading
Pressure in the arteries between heart beats (when heart is resting)
63
What is the cut off range of BP for IV sedation in dental practice and hospital setting.
>160/95 - 170/100
64
How is BMI calculated?
By weight (kg) / height (cm) (squared)
65
What is oxygen saturation (SpO2) measuring?
The percentage of haemoglobin which is bound to oxygen
66
What is used to measure oxygen saturation (SpO2)?
Pulse oximeter
67
How long are most patients encouraged to fast before conscious sedation?
2 hours
68
How long are patients with acid reflux encouraged to fast before conscious sedation?
4 hours
69
What is the typical dose of midazolam given as a drink for oral sedation?
20mg
70
You still need to cannulation for oral sedation/intranasal sedation. True of false.
True, you must still monitor the patient whilst midazolam is in their body.
71
What dose of what drug is often given as premedication for anxiety?
5-10mg diazepam
72
How long before the procedure appointment should diazepam be given?
At least 60-90 mins
73
What drug interactions does diazepam have?
Antibacterials (isoniazid, Rifampicin)
Antivirals (ritonavir)
Proton pump inhibitor (PPI’s- omeprazole)
74
When is diazepam indicated as premedication for procedures?
1. Very anxious patients (may aid them attending surgery or sleeping the night before)
2. Patients when sedation is contraindicated (to “take edge off” before more complex prolonged procedures)
75
What are the 4 contraindications for use of diazepam as a premed?
1. Hepatic impairment
2. Renal impairment
3. Pregnancy
4. Breast feeding
76
What is an alternative premed to diazepam?
Temazepam
77
What type of drug is diazepam?
Benzodiazepine
78
What are the 6 effects of benzodiazepines?
1. Anxiolytic
2. Anticonvulsant
3. Sedation (slight or intense depending on dose)
4. Amnesia
5. Muscle relaxation
6. Anaesthesia (too large or rapid a dose)
79
What are the 6 short term effects of benzodiazepines?
1. Drowsiness
2. Dizziness
3. Reduced concentration and coordination
4. Hypotension
5. Respiratory depression
6. Sexual fantasy
80
What are the 3 long term effects of benzodiazepines?
1. Tolerance
2. Dependence
3. Withdrawal symptoms
81
Define, state of controlled unconsciousness affecting the whole body, so patient does not move or feel pain, with loss of protected reflexes.
General anaesthesia
82
What are the 4 main advantages of GA?
1. Patient cooperation not required
2. Patient unaware of the procedure taking place
3. Significant amount of treatment can be carried out in one attendance
4. May be able to co-ordinate interventions with other specialties
83
What is the main disadvantage of GA?
Risk of morbidity and mortality
84
Define, how the body affects a specific substance after adminstration.
Pharmacokinetics
85
Define, the effect of drugs in the body and the mechanism of their action.
Pharmacodynamics
86
What 4 actions does the body have on an administered drug?
1. Absorption
2. Distribution
3. Metabolism
4. Excretion
87
What happens to the body after IV sedation administration?
1. Rapid rise in plasma level
2. Drug reaches brain via arterial system
3. Effects start once crossed blood-brain barrier
88
What is the hand-heart-brain circulation time of a sedative drug?
25 seconds
89
In what two ways does the patient recover from sedation?
1. Redistribution of the drug from CNS into body fat
2. Uptake and metabolism of the drug by the liver and elimination by the kidneys
90
What action of the body is responsible for the initial recovery from sedation (the alpha half-life)?
Redistribution of the drug from CNS into body fat
91
What is meant by the alpha half-life?
The time taken for the serum concentration to drop by 50%
92
What action of the body is responsible for the rest of recovery from sedation (the beta half-life)?
Elimination by the kidneys
93
What is meant by the beta half-life?
The time taken to remove half the drug from the body
94
Which half-life is used to compare the pharmacokinetic effects of sedation agents?
The elimination half-life (beta half-life)
95
Pharmacodynamically, benzodiazepines are all the same. In what three ways do they all differ?
1. Affinity for receptors (potency)
2. Half life
3. Active metabolites
96
Summarise the mechanism of benzodiazepines.
1. Chloride ions enter cell, resting membrane potential more -ve
2. -ve resting membrane potential means more difficult to fire an action potential so reducing:
- polysynaptic transmission
- depressing the uptake of sensory information
97
What does GABA stand for and what does it control?
Gamma aminobutyric acid
GABA controls the synaptic flow of chloride ions
98
What is the mechanism of action of nitrous oxide?
1. Enhances the activity of GABA
2. Has biphasic effect, where it initially enhances neuronal activity, followed by a period of inhibition
99
What are the 6 main contra-indications to use of nitrous oxide?
1. First trimester pregnancy
2. History of respiratory illnesses
3. Vitamin B-12 deficiency
4. History of substance abuse
5. Enzyme condition: methylenetetrahydrofolate reductase deficiency
6. History of mental health conditions
100
Describe, including dose, time and rate of administration, the procedure for slow IV sedation of midazolam for an adult.
Initial administration of 2-2.5mg, administered 5-10 minutes before procedure at a rate of approximately 2mg/minute.
This can be increased in steps of 1mg if required, usually total side is 3.5-5mg.
101
Describe, including dose, time and rate of administration, the procedure for slow IV sedation of midazolam for the elderly.
Initial administration of 0.5-1mg, administered 5-10 minutes before procedure at a rate of approximately 2mg/minute.
This can be increased in steps of 0.5-1mg if required, usually total side is 3.5mg.
102
What is the elimination half-life of midazolam?
1.9 hours +/- 0.9 hours
103
Where is midazolam metabolised?
Rapidly in the liver, but some metabolism also takes place in the bowel
104
What active metabolite does midazolam produce? And what is its half-life?
Alpha-hydroxymidazolam
Half-life = 1.25 hours +/- 0.25 hours (short)
105
How many times more potent is midazolam compared to diazepam?
2.5 x more potent
106
What is the impact of liver dysfunction on midazolam pharmacokinetics during IV infusion for conscious sedation?
Liver dysfunction decreases metabolism and increased plasma levels = prolonged sedative effects.
This can lead to reduced hepatic clearance of midazolam, prolonging its half-life, and a higher risk of midazolam accumulating in the bloodstream.
107
What group of drugs cannot be taken with benzodiazepines or nitrous oxide due to the increased risk of respiratory depression, sedation and hypotension?
Opioids
108
Name 6 drug types, and an example for each, which are Likely to interact with sedative drugs.
1. Antidepressants (e.g. St John’s wort)
2. Antibiotics (e.g. macrolides and fluoroquinolones)
3. Antifungals (e.g. ketoconazole)
4. Anti-seizure medications (carbamazepine and phenytoin)
5. Blood pressure medications (e.g. alpha-blockers and beta-blockers)
6. Narcotic antagonists (e.g. naloxone)
109
What two drugs cannot be taken with benzodiazepines due to increased risk of respiratory depression and hypotension?
- opioids
- propofol
110
What drug-food/supplement interactions are there for benzodiazepines?
1. Grapefruit juice: binds with enzyme cytochrome P40, increasing the level if benzodiazepine in the blood
2. St John’s wort: reduces the effect of benzodiazepine
111
What is the risk of use of benzodiazepines in pregnancy/breast feeding?
- risk of neonatal withdrawal symptom
- late pregnancy risks: neonatal hypothermia, hypotonia and respiratory depression
- small amount can present in breast milk (avoid)
112
Why are benzodiazepines advised against if a patient has renal impairment?
Due to risk of increased cerebral sensitivity
113
What is key to remember about IV sedation for the elderly?
Less drug is needed and titration should be slow
114
How does flumazenil work as a benzodiazepine antagonist?
It has a higher affinity for benzodiazepine receptor than virtually all known active drugs
115
What is the half life of flumazenil?
50 minutes
116
What is the elimination half-life of midazolam?
2 hours
117
Why can diazepam NOT be used for IV sedation?
Because the organic solvent causes vein damage
118
Describe how midazolam changes from a water soluble state to a lipid soluble state so it can penetrate the blood-brain barrier.
When you administer its called midazolam, once it enters the bloodstream it changes into an active metabolite- aplhahydroxymidazolam (lipid soluble state). Now, in this lipid soluble state, it can cross the blood-brain barrier and have a sedative effect.
