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Sedation and Special Care > Conscious sedation (IVS, IHS, ORAL) > Flashcards

Conscious sedation (IVS, IHS, ORAL) Flashcards

1
Q

Define conscious sedation

A

Technique in which the use of drug produces a state of depression of the CNS but maintains protective reflexes and verbal contact throughout the period of sedation

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2
Q

Why is loss of consciousness prevented in conscious sedation?

A

Drugs with a wide margin of safety are used to render loss of consciousness unlikely

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3
Q

What are the main indications of CS

A
  • Anxiety
  • Reduction of potentially harmful physiological effects due to anxiety in those with existing medical conditions
  • Unpleasant procedures
  • Leaning disabilities
  • Where GA should be avoided
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4
Q

What should be assessed before you decide to use CS?

A
  • Treatment required and what method of CS is suitable
  • Degree of anxiety
  • Patient expectations
  • MH, SH and DH
  • Written, informed consent
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5
Q

What can the MH tell us about the patient regarding suitability for CS

A
  • ASA grade

- Existing medical conditions

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6
Q

Importance of SH for CS

A
  • Ability to provide an escort
  • If they have children
  • Where they live/how they will get home from appt
  • Occupation
  • Alcohol and smoking
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7
Q

What can DH tell us regarding suitability for CS

A

Previous sedation and dental treatment - success, recovery etc

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8
Q

How does ASA grade reflect suitability for CS

A

ASA I and II - CS safe in practice
ASA III - CS in hospital setting only
ASA IV - GA with anaesthetist

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9
Q

How is the airway assessed (for suitability for CS)

A

LEMON

  • Look externally
  • Evaluate 3:3:2 rule
  • Mallampati score
  • Obstruction
  • Neck mobility
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10
Q

Why does the airway need to be assessed before prescription of CS

A
  • IVS causes depression of resp system

- Risk assessment for medical emergencies where the airway needs to remain patent

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11
Q

What external features indicate poor airway

A

Obsese
High arched palate
Short neck
Facial or neck trauma

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12
Q

What is the 3:3:2 rule in airway assessment

A

3cm (3 fingers) of mouth opening
3cm hyoid-mental distance indicates airway adjunct can be placed safely
2cm thyroid cartilage to to hyoid bone

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13
Q

What Mallampati score indicates difficult airway

A

IV is associated with >10% change of difficult airway

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14
Q

What are the Mallampati scores

A

Class 1 - full visibility of tonsils, soft vulva and SP
Class 2 - partial visiblity of T, SV and SP
Class 3 - soft and hard palate visible
Class 4 - only hard palate

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15
Q

List ways anxiety can be measured in a patient

A

Self report questionnaires
Visual signs
Physiological signs

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16
Q

What are visual signs of anxiety

A

Fidgeting, avoiding eye contact, talking too much/too little

Pale, sweaty or shaking

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17
Q

What are physiological signs of anxiety

A

High BP (palpitations)
Increased pulse
Oxygen saturation reduced

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18
Q

What are medical conditions which may benefit from CS

A
  • Angina
  • Controlled hypertension
  • Asthma
  • Epilepsy
  • Movement disorders e.g. Huntingtons
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19
Q

Which medical conditions will CS technique have to be modified

A

Controlled heart failure or airway disease
Chronic anaemia
Well controlled diabetics

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20
Q

Which medical conditions requires caution for use of CS?

A
  • Severe cardio-resp disease
  • Hepatic disease
  • Severe psychological illness
  • Drug or alcohol abuse
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21
Q

What are the options for pain management from simplest to most advanced

A
  • LA alone
  • LA and IVS
  • LA and IHS
  • LA and OS or INS (possibly before IVS)
  • GA
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22
Q

What is the age requirement for IVS and why

A

16+

Children show resistance and even paradoxical reaction to benzodiazepines

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23
Q

What is the benefit of midazolam over diazepam in IVS

A
  • Double the strength
  • Shorter half life
  • No significant metabolites allowing smoother and quicker recovery
  • More amensic effect
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24
Q

What technique is midazolam given in IVS

A

Titration technique

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25
Q

What are the properties of midazolam

A
  • Water soluble benzodiazepine
  • Clear liquid
  • Non-irritant
  • 5ml ampoules containing 5mg
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26
Q

Define pharmacokinetics

A

What the body does to the drug

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27
Q

Define pharmacodynamics

A

What the drug does to the body

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28
Q

List pharmacodynamics of midazolam in IVS

A
  • Rapid onset
  • Acute detachment for 20-30 mins then approx 1 hour relaxation
  • Anxiolysis
  • Hypnosis
  • Amnesia
  • Muscle relaxation (thus anticonvulsant)
  • Respiratory depression
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29
Q

What is the significance of respiratory depression in iVS

A

It is the most important adverse effect, which can be enhanced by oversedation or rapid injection and requires monitoring via pulse oximeter (mandatory)

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30
Q

List pharmacokinetics of midazolam

A
  • Initial recovery via redistribution
  • Metabolised in liver
  • Metabolites excreted through kidneys
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31
Q

What is the half life and recovery of midazolam

A

Approx 4 hours half life

8 hours to recovery

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32
Q

Contraindications for IVS with midazolam

A
  • Allergy to benzos
  • Pregnancy or breastfeeding
  • Severe psychoses
  • Alcohol or drug abuse
  • Liver or kidney impairment
  • Needle phobia
  • Doubts about escort
  • Poor sedation history (poor compliance or response)
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33
Q

What drug interactions occur with midazolam

A
  • Other sedatives or narcotic analgesics
  • Antiepileptics
  • Antihypertensives
  • Anti parkinson
  • Cimetidine (gord)
  • Disulfiram (alcoholism)
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34
Q

How is respiration controlled and why is sedation safe?

A
  • Driven by CO2 (ph) and is GABA-mediated

- Controlled by higher centres which are maintained in CS

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35
Q

What is GABA

A
  • Main NT in the CNS that works on postsynaptic receptors by opening chloride ion channels and preventing depolarisation of propagation of action potentials
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36
Q

How do benzodiazepines affect GABA

A

They increase the effect of GABA

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37
Q

What is the reversal agent for midazolam?

A

Flumazenil

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38
Q

How does flumazenil reverse midazolam

A

It is a competitive inhibitor for GABA

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39
Q

Indications for flumazenil

A

Emergency e.g. overdose of idiosyncratic response
Slow recovery
Difficult journey home

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40
Q

Why does the pt need to be monitored even after giving flumazenil

A
  • Flumazenil has a short life 50mins less than midazolam and re-sedation is possible *but no real risk with this
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41
Q

Why does the IV remain until the moment of discharge

A

In case we need to administer flumazenil

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42
Q

What is the pre op checklist for iVS

A

Escort and transport home

Patient eaten

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43
Q

What are the pre-sedation records required

A

Equipment checklist
MH checked
Second stage written consent
BP and O2 saturation

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44
Q

What location is venepuncture common in

A

Dorsum of hand

Antecubital fossa

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45
Q

Describe venepuncture sequence

A

Approach best vein at shallow angle
Reduce angle as you advance and push whole needle in gently
Observe flashback and vial fills with blood
Secure

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46
Q

What is the titration sequence for healthy patients

A

2mg over 30s
Wait 60-90s
1mg every 30s until sedated

47
Q

What is the titration sequence for elderly patients

A

1mg very slowly
Wait 4 mins
0.5mg every 2 minutes until sedated

48
Q

What are signs of sedation

A

Muscle relaxation
Relief of anxiety - maybe acceptance of mouth prop, LA
Slurred speech and slowed responses

49
Q

What are signs of extravascular injection

A

Pain on injection

Swelling at cannulation site

50
Q

Why do we flush with saline before midazolam?

A

Ensure correct position of cannula

51
Q

Management of extravascular injection

A

Reposition needle

If not possible, remove cannulae and pick site mesial to the previous site

52
Q

Management of poorly visible veins

A

Torniquet, hold hand below heart and pump fist
Ask another clinician
Consider alternative site or technique (IHS)

53
Q

What do we monitor during IVS

A
  • Pulse oximeter for O2 saturation and pulse rate and regularity
  • Visually - colour, breathing, airway
54
Q

Management of a drop in oxygen saturation

A

Ask patient to take deep breaths

Repeat = use supplemental oxygen

55
Q

What do we assess before discharging patient from IVS

A

Ability to walk in a straight line
Appear orientated
Able to talk coherently

56
Q

How long is recovery for IVS

A

Initial recovery in chair

30-40 mins in recovery aea

57
Q

What 3 things are mandatory before discharge?

A
  • Discharge blood pressure
  • Written and verbal post op instructions to pt and escort
  • Remove cannulae and apply dressing
58
Q

How do you record IVS prescription

A

5mg in 5ml, IV in titration

re-write it for the number of ampoules given

59
Q

What do we use for inhalational sedation in dentistry

A

Nitrous oxide and oxygen in sub-anaesthetic concenrations

60
Q

What are the aims of IHS

A

Produce a comfortable, relaxed, awake pt who is able to cooperate without interference, but remains conscious and retains laryngeal reflexes

61
Q

Indications for inhalation sedation

A
  • CHILDREN
  • Anxiety
  • Needle phobic
  • Gag reflex
  • Unpleasant procedures
  • Medically compromised
  • Where other sedation methods are CI (pregnancy) or if GA CI
62
Q

What are absolute contraindications for IHS

A
  • Acute and chronic nasal obstruction
  • 1st trimester pregnancy
  • Inability to cooperate or understand (young or psychoses)
  • Vitamin b12 deficiency
63
Q

What are the cautions for IHS

A
  • Severe respiratory disease - COPD
  • Severe psychotic disorders
  • Nasal or facial deformity or recent eye surgery
  • Nasal hood fear
64
Q

Why is COPD a CI for iHS

A

They rely on low concentrations of oxygen to breathe, therefore high o2 during procedures may cause difficulty breathing

65
Q

Pharmacology of nitrous oxide

A 
Colourless 
Slightly sweet odour and taste 
Heavier than air 
Non-flammable
Non-irritant 
Low potency (wide margin of safety)
66
Q

Pharmcodynamics of nitrous oxide

A 
Anxiolytic 
Sedative 
Weak analgesic
Small depression in myocardial function or vasodilation
Euphoria and mood alteration
67
Q

What is the onset of nitrous oxide

A

Rapid - 5mins

68
Q

Why is onset and elimination of nitrous oxide so rapid

A

It does not enter metabolic pathways and it is poorly soluble allowing rapid distribution

69
Q

How long does it take for nitrous oxide to be eliminated

A

90% at 10 mins

70
Q

How is nitrous oxide excreted

A

Via respiratory system

71
Q

List advantages of using nitrous oxide

A
  • Rapid onset and recovery
  • No needles (until LA used)
  • Easily altered or discontinued drug levels
  • Suppresses gag reflex
  • Continuous, constant sedation for duration required
  • Effective in children
  • Some level of analgesia
72
Q

List disadvantages of nitrous oxide

A
  • Support needed throughout for it to work
  • Mask may limit access of upper anteriors
  • Pollution of NO (greenhouse gas)
  • May not work in severe anxiety/phobia
  • Diffusion hypoxia
73
Q

What is the equipment required for IHS

A
  • Gases (o2 and no) - can be piped or cylinders
  • Nasal hood
  • Tubing
  • Reservoir bags
  • Emergency equipment and drugs
  • Scavenging unit
  • Instruments for the procedure
74
Q

What are the safety mechanisms for IHS

A
  • Pin index system
  • Oxygen fail safe
  • Max NO allowed is 70% (means you cannot give 100% NO)
75
Q

What is the pin index system

A
  • Oxygen and NO cylinders have different sized holes for tubing to ensure the right one is attached (prevents giving 100% NO rather than o2)
76
Q

What is the oxygen fail safe?

A

If oxygen stops working, the NO cuts off

77
Q

How so we adjust the reservoir bag?

A
  • According to patient breathing

- Usually tidal volume x breaths per minute

78
Q

Define mixture control (IHS)

A

How much % oxygen and % NO given

79
Q

Define flow control (IHS)

A

How much gas is given

80
Q

Pre-op checklist for IHS

A
  • Pt can breathe well
  • Eaten
  • Escort
  • BP
  • Consent
81
Q

How should the nasal hood fit?

A

Good seal without gaps around eyes and nose

82
Q

Describe the sequence for IHS

A
  • 100% oxygen
  • 10% NO for one minute and engage pt
  • 20% NO for one minute and engage pt
  • 5% increments until sedated
83
Q

What is adequate sedation for iHS

A

Pt aware of operative procedure and is accepting it without being fearful

84
Q

What is the normal flow rate for oxygen in IHS

A

3-10 litres/minute

85
Q

What is the usual % of NO in IHS

A

20-50%

86
Q

How do we monitor pts during IHS

A
  • Breathing rate (chest and reservoir bag)
  • Airway patency
  • Actions and responses
87
Q

When is pulse oximetry used in IHS

A
  • If severe medical conditions

- It is not routine

88
Q

What do we do in IHS after we finish the procedure

A

Flush with 100% oxygen for 5 mins

89
Q

List symptoms of IHS

A
  • Sensory disturbance
  • Tingling or light headed
  • Visual or auditory changes
  • Temp changes
  • Floating
  • Day dreaming
  • Euphoria
90
Q

What are signs of effective IHS

A
  • Reduced body and facial tension
  • Laughing
  • Slowed response
  • Acceptance of tx
  • Reduced hr and resp rate
  • Reduced frequency of blinking
91
Q

What are signs of oversedation with NO

A
  • Nausea
  • Rigid muscles
  • Mouth closure
  • Disorientated or apprehensive
  • Hallucinations
  • Irritable
  • Unresponsive
92
Q

How do we manage oversedation of NO

A
  • Reduce dose and monitor

- If you cannot control then abandon

93
Q

How can we enhance the effects of IHS

A
  • Calm monotone voice for hypnotic effect
  • Imagery and visualisation
  • Ceiling pictures
  • Lighting and music
  • No disturbances e.g. others entering room
94
Q

What are the types of scavenging for NO

A
  • Passive - open windows and doors, using fans

- Active - suctions or scavenging units

95
Q

What are the effects of nitrous oxide pollution/toxicity

A
  • Distal renal tubule calcification
  • CNS - neuropathy
  • Reduced sperm count
  • Bone marrow depression and decreased leukocyte functioning
96
Q

What is the weighted maximum dose suggested by HSE for NO?

A

Max 100ppm NO in a working environment over 8 hours

97
Q

When do we use oral or intranasal sedation

A
  • Unable to accept venepuncture

- Used before venepuncture to reduce anxiety

98
Q

What is the most common drug for oral and intranasal sedation

A

Midazolam

99
Q

Why is OS and intranasal sedation avoided

A

Less predictable as the dose is not titrated according to response

100
Q

Instructions for patients before procedure (CS)

A
  • Take routine medication
  • Light meal
  • No alcohol or drugs
  • Bring escort
101
Q

What is a suitable escort

A

Over 18 who can physically support the patient, and has no other responsibilities with them e.g. children, can understand English (For post op instructions)

102
Q

What are post op instructions for CS

A
  • FOR 24 HOURS -
  • Do not travel alone - with escort only, ideally by car
  • Do not drive or ride a bike
  • Do not operate machinery
  • Do not drink alcohol
  • Do not return to work or sign legal documents
103
Q

Venous assessment before IVS

A
  • Check quantity, quality and position of veins suitable for access (on hands and antecubital fossa)
  • Ask patient where they usually get bloods taken from
104
Q

Role of diazepam as a premedication for IVS

A
  • Low dose used to relax the patient the night before the appointment to allow a good night’s rest (or the day of the appointment)
105
Q

Dose of premedication diazepam for IVS

A

2mg, 5mg or 10mg

Usually start at 2mg to assess the response

106
Q

How is respiratory depression enhanced in IVS?

A
  • Administrating an excessively rapid ‘bolus’
  • Overdosage
  • Those with existing respiratory conditions
  • Patients who have taken other depressants e.g. opiates or alcohol
107
Q

When do you have to be careful with fluamazenil?

A

If you suspect allergy to the midazolam (as flumazenil is also a benzodiazepine)

108
Q

How to administer flumazenil

A
  • IV
  • 1ml increments at 30s intervals until 5ml given
  • Observe the patient
109
Q

Advantages of IVS as a CS technique

A
  • Site of administration away from operating site
  • Single dose
  • Rapid onset
  • Mouth breathing is not important
  • No NO pollution or occupational risk
110
Q

Disadvantages of IVS as a CS technique

A
  • Needs an escort and must rest for the rest of the day
  • May increase anxiety by disinhibition effect
  • Intravascular injection may damage vessels
  • Cannot be discontinued or removed once given
  • Profound respiratory depression with overdose
111
Q

How much should the reservoir bag inflate and deflate?

A

Collapse gently by 1/4 and then inflate by 1/4

If the balloon is too inflated then reduce the flow rate

112
Q

How many breathes per minute is common?

A

12-20

113
Q

How much air is inhaled with eat breath

A

500ml

Sedation and Special Care (1 decks)

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