Special Care (PTSR)

Question 1

What are the systemic effects of Nitrous Oxide on:

1. CNS?
2. Respiratory system?
3. Haemotopoeitic system?
4. GI, Liver & Kidney?

Answer 1

1. Vasodilation
2. Respiratory depression (Reduced rate and depth)
3. Bone marrow suppression
4. NOTHING :)

Question 2

What is meant by the “Triad of Anaesthesia”?

What anaesthetic agent does not achieve one of these?

Answer 2

1. Hypnosis/Sedation
2. Muscle relaxation
3. Analgesia

MIDAZOLAM (pre-GA anxiolytic or conscious sedative) does NOT provide Analgesia

Question 3

What drug is used to reverse effects of Midazolam? How?

When might its use be contra-indicated? (2)

Answer 3

Flumazenil (Competetive antagonist at Benzodiazepine receptor)

Reverses ALL effects of Midazolam (Muscle relaxation, Respiratory depression, Cardiovascular effects) EXCEPT Anterograde Amnesia

Contra-indications:

• Epileptic Px on CNS active drugs (may reverse effects of anti-convulsant meds → epileptic fit)
• Midazolam allergies (Flumazenil is a benzodiazepine too!)

Question 4

Define the following:

1. Pharmacokinetics
2. Drug Distribution
3. Drug Clearance/Elimination
4. Pharmacodynamics

Answer 4

PHARMACOKINETICS = The movement of a drug through the body, split into a 2-part curve:

1. Drug Distribution
2. Drug Elimination

DRUG DISTRIBUTION = The movement of a drug in which peak blood level represents the amount of drug injected. This falls as the drug is distributed into the tissues

DRUG ELIMINATION = Volume of plasma which is cleared of the drug within a unit time

PHARMACODYNAMICS = What the drug does to an individual

DYNAMICS =

Question 5

What are the 2 stages of recovery after GA?

Answer 5

1. Fully awake, protective reflexes return, Observations stabilise and Pain is controlled (analgesia)
2. Ready for discharge with “reasonable adjustments” with responsible adult escort

Question 6

What are 4 signs of oversedation?

How is:

1. Small
2. Gross

oversedation managed?

Answer 6

• Nausea/Vomiting
• Uncooperative (e.g. constant mouth closing)
• Irregular respiratory rate
• Loss of cosciousness!

SMALL OD (e.g. uncooperative) ⇒ Wait few mins (usually resolves) and give O₂

GROSS OD (e.g. profound respiratory depression) ⇒ STOP, Secure airway, ventilate if not breathing and reverse with FLUMAZENIL

Question 7

Why is pre-medication given before GA? (3)

What are the 2 main types? (give examples)

Answer 7

1. Reduce anxiety
2. Reduce pre and post-op pain
3. Produce amnesia

• (Oral) Sedatives (e.g. Midazolam or Ketamine) → Anxiolysis
• Topical LA creams (used pre-cannula)

Question 8

RLH accept GA referals for patients in ASA 1-3, define the American Society of Anaesthesia (ASA) classifications 1-6…

Answer 8

Question 9

What is the MOA of Midazolam?

How is it’s function incfluenced by: Age and CNS active drug use?

Answer 9

GABA receptor agonist (present throughout the body) → Cl^- entry → Cell inhibition

Age = Decrease in receptors around the body, slower circulation and paradoxical effects

CNS Active Drug Users = Altered receptor activity (they become “Hypo-active” responders who require more drug to sedate)

Question 10

What is the 2 stage test for Capacity?

What are 5 options if the Px lacks capacity?

Answer 10

1. Is there an impairment or disturbance in the functioning of Px mind or brain?
2. If so, is the impairment sufficient that the person lacks capacity to make a decision?

• Act in Px best interest
• Advanced directives (Px in cognitive decline makes decisions in advance)
• Lasting Power of Attorney (nominated by Px)
• Court-Appointed deputy
• Independent Mental Capcity Advocate (IMCA)

Question 11

What are 6 signs/symptoms of anxiety?

Answer 11

• Behavioural changes: Excessive talking (delay tactic), Lateness, DNA or Aggression
• Pallor or flushing of face
• Sweatiness (esp. facial)
• Increased HR
• Dry mouth
• Fainting

Question 12

What are the 4 “Pharmacodynamics” (effects) of Midazolam?

Answer 12

1. Muscle relaxant
2. Respiratory depression (mild) - Pulse oximeter monitoring
3. Anterograde Amnesia
4. Cardiovascular effects via PsNS - Decreased MAP, CO, SV and Systemic vascular resistance

Question 13

Why are patients “starved” pre-GA?

What fasting instructions should be given to patients?

Answer 13

To reduce the likelihood of stomach contents being regurgitated and then aspirated into the lungs

• Stop eating solid foods 6 HOURS before GA (e.g. 2am for 8am GA)
• Stop drinking fluids for 2 HOURS before GA (e.g. 6am for 8am GA)

Medications can be taken between this period, except if contraindicated (e.g. Type 2 diabetics should NOT take morning meds)

Question 14

Outline the differences in:

1. Px response during procedure
2. Px airways (un/affected & whether intervention required)
3. Spontaneous ventilation
4. Cardiovascular function

between Pre-medication (Anxiolytic Sedatives), Conscious Sedation and General Sedation…

Answer 14

Question 15

What are 5 contra-indications to GA?

(3 are MH conditions)

Answer 15

1. Allergies to GA drugs (e.g. Propafol, Fentanyl, Sevoflurane)
2. Advanced cardio-respiratory disease
3. Suxamethonium apnoea
4. Malignant Hyperthermia
5. No escort

Question 16

What should a “Recovered” GA Px be able to do?

Answer 16

• Stand and walk unaided
• Coordinate fine movements
• Judge distance and time correctly

Px should not be discharged less than 40-60 mins following last sedative increment

Question 17

What conditions may affect airway access during GA?

Answer 17

• Arthritis → Limited opening
• Treacher Collins syndrome → Small jaw
• Acromegaly → Large/Wide jaw
• Ankylosing Spondylitis → Unstable cervical spine on chair

Question 18

What is meant by “Sedation”?

What 3 things do you expect to see in a Sedated patient?

How can this be shown clinically?

Answer 18

Sedation = The use of drug(s) to produce a state of CNS depression, enabling treatment to be carried out, but during which verbal contact is maintained with the patient throughout the period of stabilisation

1. Px conscious (but relaxed)
2. Protective reflexes maintained
3. Able to understand and respond to verbal cues (cooperative)

CLINICALLY:

• Normal repsiratory rate
• Normal eye movement (follows finger)
• Protective reflexes (including eyelid) intact

Question 19

What is the definition of “Disability”?

What are the 2 main models of Disability?

Answer 19

Disability = Any restriction or lack of ability to perform an activity in the manner considered normal for a human being

1. Medical (disability caused by impairment)
2. Social (disability caused by way society is organised, e.g. no wheelchair access)

Question 20

What are the side effects of GA?

What is the risk of:

1. Awareness?
2. Anaphylaxis?
3. Death?

Answer 20

• Nausea/Vomitting
• Shivering (Patient warming needed during procedure)
• Sore throat/nose
• Chest infection
• Trauma to dentition (through airway maintenance tubes)

Awareness = 1:15,000

Anaphylaxis = 1:15,000

Death = 1:100,000

Question 21

What are the 3 main forms of access we are concerned with?

Answer 21

Access to:

1. Dental Surgery
2. Dental Chair
3. Mouth (e.g. psychological or pharmalogical intervension)

Question 22

In what 3 ways are airways maintained during GA?

Answer 22

1. Nasal endotracheal tube
2. Oral endotracheal tube
3. Laryngeal mask airway

Question 23

What are the 2 mechanisms in which Midazolam causes Respiratory Depression?

Answer 23

1. Relaxation of respiratory muscles → Lower TV and RR
2. Reduced sensitivity of central CO₂ and O₂chemoreceptors to systemic changes

Question 24

What is the definition of a:

1. Impairment?
2. Disability?
3. Handicap?

Answer 24

1. Loss or abnormality of psychological or anatomical or function
2. Restriction or lack of ability to perform an activity in the manner considered “normal for a human being
3. The result when an individual with an impairment cannot fulfil a normal role

Question 25

Anxiety affects 1/3rd adults at the dentist... What may be the aetiology? (3) What might trigger the anxiety? (4)

Answer 25

Aetiology: * Past experience * Feeling of lack of control * Classical conditioning (e.g. evil dentist portrayal in films or parental influence) Triggers: * Anticipation * Visual (e.g. seeing dental instruments) * Olfactory (e.g. hospital smell) * Auditory (e.g. sound of drill)

Question 26

What does pre-assessment for GA involve?

Answer 26

* Identify risk factors * Carry out necessary Special Investigations (Weight, Blood tests, Echocardiogram, Electrocardiograph & US) * Plan anaesthetic care - Liase with anaesthetist * Gain consent (written and verbal) * Give fasting instructions and importance of escort

Question 27

What doses of Midazolam are given during titration to: 1. Fit and healthy patient? 2. Elderly patient? 3. Overweight patient?

Answer 27

Question 28

What 3 requirements should be met for valid consent?

Answer 28

1. Capacity (2-stage test) 2. Voluntary 3. Informed

Question 29

What is meant by General Anaesthesia? (definition) What are 4 general indications for its use and 3 special care specific indications?

Answer 29

GA = A drug induced state of reversible, controlled unconsciousness in which the patient is NOT rousable. * Anxious Px with OSA (CI for IHS) * Previous failed sedations * Multiple extraction or extraction of 3rd molars * Maxillofacial surgery * Aspiration risk * Challenging behaviours * Multipli-disciplinary risk (e.g. dental care done at same time as gastric surgery)

Question 30

Outline the 4 main stages in GA, from Pre-medication → Recovery (Include example medications used)

Answer 30

**PRE-MEDICATION** Often _Sedatives_ to give Anxiolytic effect * Oral Sedatives (e.g. Mizadolam or Ketamine) * Topical LA cream *(pre-cannula)* **GA INDUCTION** * IV (e.g. Propofol, Fentanyl or Atacurium) * IH (e.g. Sevoflurane, NO₂/O₂) **INTRA-OPERATIVE CARE** * Maintenance = Propofol or Sevoflurane * Analgesia = Fentanyl or LA * Anti-emetics = Odansetron or Cyclizine * Fluids = Saline * Venous Thrombosis Prophylaxis = Enoxaparin or Mechanical (leg compression) aids * Patient warming *- Shivering SE* * Steroids Monitoring = ECG/HR, Arterial BP, O₂ saturation, End-tidal CO₂ ("Capnography") and Anaesthetic gas concentrations **RECOVERY** 2 stage recovery, discharge with "reasonable adjustments" with responsible escort

Question 31

What are the 5 statutory principles of the 2005 Mental Health Act, regarding capacity and consent?

Answer 31

1. Presume Capacity 2. Give necessary support (e.g. pictures, communication aids) 3. Respect Px decision, including those deemed unwise 4. Act in Px best interest (if lacking capacity) 5. Consider the least invasive/restrictive Tx option

Question 32

What is the: 1. Distribution Half-Life 2. Elimination Half-Life 3. Therapeutic index of Midazolam? How does (1) compare to that of Flumazenil and why is this significant?

Answer 32

1. 6-15 mins (moderate onset) 2. 1-3 hours (relatively short half life) 3. High Flumazenil has a shorter elimination half-life (1 hour) than Midazolam - significant in its use to reverse Midazolam OD. Should be sufficient time to avoid re-sedation, UNLESS: Px recieved large dose or is not healthy

Question 33

How might a patient with: 1. Suxamethonium apnoea 2. Malignant Hyperthermia be affected by GA?

Answer 33

1. **Suxamthonium apnoea** = *Prolonged paralysis post-anaesthetic due to patients lack of enzymes to metabolise Suxamthonium (Succinylcholine)* 2. **Malignant Hyperthermia** = *Rapid rise in body temperature and severe muscle contractions* Both inherited disorders CI in GA

Question 34

Why is a pulse oximeter mandatory in Midazolam IV conscious sedation?

Answer 34

It causes RESPIRATORY DEPRESSION, which must be monitored to avoid any adverse effects

Question 35

Why do we Titrate medications in conscious sedation? What doses and time intervals is Midazolam given in a fit and healthy patient?

Answer 35

We titrate (give small amounts of medications at a time) due to variable responses in patients. *N.B. We cannot titrate oral medications as longer distribution times* _MEAN DOSE:_ **2-7.5mg** * **2mg** given over **30 secs** * Wait 60-90 seconds * **1mg** given over **30 seconds** till adequate sedation

Question 36

When giving Midazolam for sedation, what patients might: 1. Hypo-respond *(require more)* ? 2. Hyper-respond *(require less)* ? 3. have "Paradoxical" effects?

Answer 36

1. CNS active drug users (e.g. cocaine) 2. CNS-reducing drug users (e.g. elderly parkinsons, epileptics) 3. Older and Younger patients *Px taking "psychoactive drugs" may also have unpredicable recovery behaviour post-sedation*

Question 37

What is the usual dose of Flumazenil dose given? How is Flumazenil titrated to: 1. Reverse sedation at end of treatment? 2. Overcome a Midazolam OD? (Initial dose & Further doses)

Answer 37

0. 2-0.6mg 1. REVERSAL * Inital dose = 0.2mg over 15 seconds * Further = 0.1mg/min (to max 1mg) 2. OVERDOSE * Inital dose = 0.3mg over 30 seconds * Further 0.3mg/30s (to max of 2mg)

Question 38

What is meant by "Challenging Behaviours"?

Answer 38

Culturally abnormal behaviours of such intensity, frequency or duration that the physical safety of a person or those around them is placed in serious jeoparty. Also behaviour that is likely to seriously limit the use of, or result in a person being denied access to community facilities.