Pain and anxiety Flashcards
1
Q
What is sedation?
A
It is a continuum which extends from normal consciousness to complete unresponsiveness. There is minimal, moderate, deep and general. Conscious sedation is a technique where a drug depresses the CNS to allow operative treatment with the minimum physiological and psychological stress. Modify patients state of mind and allow communication and the patients response to commands. Both verbal contact and protective reflexes are maintained in the patient throughout sedation. You need a good safety margin so that consciousness is maintained and airway protected.
2
Q
How are gases transported in and out of the body by the respiratory system?
A
Ventilation is the moving of gas into and out of the lungs. Diffusion is the transfer of gases from the lungs into the blood. Oxygen is transported by haemoglobin in the blood. It is involved in energy metabolism to produce energy for the body. Oxidation is the use of oxygen to produce energy within the cell and the production of carbon dioxide. The waste product is carbon dioxide which is collected by diffusion into the veins. It goes back to the lungs inot the alveoli and out of the body.
3
Q
What are the structures in the upper airway?
A
The nasal cavity contains the superior, middle and inferior turbinates. There is the hard and soft palates. The nasopharynx contains the tonsils/adenoids and uvula. The oropharynx contains the tongue. The laryngopharynx/hypopharynx contains the vallecula and epiglottis. The larynx contains the oesophagus and trachea. There is also the glottic opening, vocal cords, thyroid cartilage, cricothyroid cartilage, cricoid cartilage and thyroid gland.
4
Q
What are the structures in the lower airway?
A
There is the primary, secondary and tertiary bronchus. There is the bronchiole, terminal bronchiole and alveoli.
5
Q
What is inspiration and expiration?
A
Inspiration is an active process initiated by the diaphragm. It is supported by intercostals. Accessory muscles are used for more vigorous inhalation. The normal rate is 10-18 per minute. Expiration is a passive process and it is the elastic recoil of lungs. Forced expiration involves abdominal and intercostals.
Air is inhaled when the diaphragm contracts. The intercostals pull the ribs away and expand the lungs. When relaxed they recoil back and air is exhaled.
6
Q
How does gas exchange occur?
A
Gas exchange occurs within the alveoli. The wall is a single layer thick and it is 0.2 micrometers. It is adjacent to the pulmonary capillary wall. Gases diffuse down concentration gradients.
7
Q
How is oxygen transported around the body and used in the tissues?
A
The oxygen binds to haemoglobin. Each molecule can carry 4 oxygen (O2) molecules. It is carried within red blood cells. CaO2= 1.34 x Hb x SpO2. We rely on adequate circulation to transport to tissues. Delivery = CaO2 x Cardiac Output. Properties of haemoglobin mean it releases O2 when it gets to the tissues. The mitochondria uses the oxygen for metabolism. Glucose is the main energy source and combined with oxygen it produces CO2.
8
Q
How does anaemia affect sedation?
A
People with anaemia have less haemoglobin so care is needed with sedation as reduced oxygen will affect them more.
9
Q
What is CaO2?
A
CaO2 is arterial oxygen content and refers to the volume of oxygen delivered to the tissues per unit blood volume.
10
Q
How is the respiratory system controlled?
A
It is by the autonomic nervous system - brainstem, medulla and pons. There is the respiratory centre which responds to blood CO2 levels.
11
Q
What is the basic function of the cardiovascular system?
A
The basic function is to deliver oxygenated blood to the body organs and tissues for metabolism. There is tissue perfusion.
12
Q
How does blood pass through the cardiovascular system?
A
There is a parallel pumping system. The right side is oxygenated blood. It carries oxygen from the lungs. From the left ventricle it pumps up through the aorta and goes to the head and the rest of the body. Then the blood comes back through the superior and inferior vena cava to the right atrium and ventricle. It is then pumped back through the pulmonary vessels back to the lungs.
13
Q
What happens with inadequate perfusion?
A
With inadequate perfusion, organs and tissues quickly begin to fail. Cardiac ischaemia leads to angina and myocardial infarction. Cerebral ischaemia leads to faint/collapse and stroke. Lung – hypoxia.
14
Q
What is the main determinant of organ perfusion?
A
Blood pressure.
15
Q
How is BP displayed and how is this calculated?
A
BP is displayed as systolic, diastolic and mean MAP. 120/60 (80). The mean is calculated as diastolic + 1/3 (systolic-diastolic). Thankfully modern machines will calculate it for you. Normal MAP is 80mmHg.
16
Q
How is blood pressure regulated?
A
Blood pressure has autoregulation. There is the sympathetic and parasympathetic system. Sympathetic will increase the blood flow and parasympathetic will decrease the blood flow and heart rate. When the tissue perfusion reduces autoregulation will try to increase the perfusion. When the person gets older and arteries get clogged (arteriosclerosis) so blood pressure will be higher to ensure perfusion. Autoregulation ensures adequate perfusion over a range of MAPs. Limits will shift in people with chronic hypertension.
17
Q
What is blood pressure determined by?
A
Blood pressure is determined by 2 main components which are cardiac output CO and systemic vascular resistance SVR. Cardiac output is the amount of blood ejected by the heart per minute. The average is 5 litres per minute. It is determined by the heart rate HR and the stroke volume SV. HR between 50-180 have little effect. SV is reduced by dehydration/blood loss, ischaemic heart disease/heart failure and anaesthetic drugs.
Systemic vascular resistance is the resistance produced by the vascular system to the flow of blood. It is mainly small arterioles in the body. Constriction increases SVR and hence BP. Dilation decreases SVR and hence BP. SVR decreased by sedative drugs, anaphylaxis and sepsis/infection.
18
Q
What is the acute and chronic control of blood pressure?
A
Acute:
- Baroreceptors in aortic arch and internal carotids
- Send signals to brain stem
- Autonomic nervous system alters rate and strength of heart contraction and constriction of blood vessels.
Chronic:
- Renin-angiotensin system
- Aldosterone
- Chronic regulation of blood sodium concentration and body fluid retention
19
Q
What are the commonly used drugs in sedation?
A
- Benzodiazepines e.g. midazolam which acts on GABA receptors
- Opiates - fentanyl, remifentanil (opioids) act on Mu receptors
- Others - propofol (potent and short acting so continuous infusion), ketamine, dexomethomedine (alpha2 agonist)
20
Q
What are the advantages and adverse effects of midazolam?
A
Advantages: - Quick onset - Short action of duration - Minimal cardiovascular effects Adverse: - Respiratory depression - Airway obstruction
21
Q
What is fentanyl?
A
Fentanyl is a man made synthetic opiate drug. It provides analgesia and sedation. The onset is 1-2 minutes and the peak is 10-15 minutes and the duration is 30-60 minutes. The dosing is 25mcg (0.5ml) bolus up to 200mcg max.
22
Q
What are the advantages and adverse effects of fentanyl?
A
Advantages: - Provides analgesia as well as sedation - Fast onset - Short duration of action Adverse: - Hypotension and bradycardia - Respiratory depression - Nausea and vomiting
23
Q
What is remifentanil?
A
Remifentanil is an ultra short acting opiate. It has a very potent analgesic effect. It has to be administered by continuous infusion via syringe driver. Will stop working within a minute of ending infusion.
24
Q
What are the advantages and adverse effects of remifentanil?
A
Advantages: - Excellent analgesic properties - Extremely short duration of action 8 minutes Adverse: - Hypotension - Bradycardia - Respiratory depression and apnoea
25
What is propofol?
Propofol is an intravenous anaesthetic induction agent. The onset is 30 seconds and the duration is 10-15 minutes. The dosage is 10-20mg (1-2mls) every 5 minutes or by continuous infusion.
26
What are the advantages and adverse effects of propofol?
Advantages:
- Very potent sedative
- Rapid onset
Adverse:
- Only for use by trained sedationist or anaesthetic staff
- Can rapidly progress to general anaesthesia
- Significant cardiovascular and respiratory depression
27
What is polypharmacy and the benefits and risks?
Polypharmacy is the use of more than one drug. It can have advantages as different drugs give different effects e.g. opiate and benzodiazepine gives both sedation and analgesia. Giving a second drug means you can use less of the first drug and so potentially reducing side effects. But there is greater risk of overdosing and over-sedating patients. Drugs with the same side effects will have synergistic action and make those side effects even more likely.
28
Why is knowledge of time to peak effect even more important with polypharmacy?
Must be aware of time to peak effect of the drugs you are using. Midazolam 5-7 minutes, fentanyl 10-15 minutes and propofol 1minute. Not waiting for full effect of first drug may lead to dosing of second drug peaking with first drug. Leads to significant over-sedation and side effects.
29
What is the history of drugs used for GA?
- 1846 ether
- 1847 chloroform
- Problems of sudden death/liver damage
- 1877 cocaine
- LA infiltration, nerve blocks, spinal and epidural
- 1920-30 intubation
- Barbiturates as induction agents
- 1943 muscle relaxants
- 1950 halothane – reduced toxicity
30
What can cause difficulty with dental treatment?
- Co-operation
- Anxiety/phobia
- Medical conditions/mental health issues
- Involuntary movements
- More complex treatments/quadrant dentistry
- MDAs phobia 19 or above
31
What are some basic behavioural management strategies?
- Tell, show, do
- Positive distraction e.g. music, ipod, TV
- Relaxation
- Systematic desensitisation - gradual acclimatisation
- Hypnosis
32
What are some alternative behaviour management strategies?
- Acupuncture
| - Drugs - oral/HIS/IV sedation
33
What is premedication?
Diazepam is in the DPF/ask GMP. Diazepam can be irritant to the skin and has a hangover effect so takes longer to wear off. 2mg oral dose of diazepam can be prescribed to be taken a few hours before or the night before. Safer to ask GMP to prescribe it.
34
What are the properties of an ideal sedation agent?
- Simple to administer
- Rapid onset
- Predictable action/duration
- Rapid recovery
- Rapid metabolism/excretion
- Low incidence of side effects
35
How can oral sedation be used in dentistry?
The patient can have oral premedication at home:
- Reduces anxiety in advance of treatment and facilitates attendance
- Diazepam 2-5mg in the morning of treatment/attendance
- Temezepam 10mg the night before
- Ask GMP for advice/to prescribe
The patient can have oral sedation in the surgery with monitoring. It will be 10-20mg Temazepam.
Oral sedation is simple to administer, predictable action/duration and low incidence of side effects. There is no rapid onset, rapid recovery or rapid metabolism/excretion. You need specialist monitoring/training.
36
What are the features of inhalation sedation?
- Specialist equipment/training and surgery requirements (scavenging)
- Need patent nasal airway
- Good for children
- Minimal intervention
- Analgesic
- Hazards of chronic exposure
- Simple to administer
- Rapid onset
- Predictable action/duration
- Rapid recovery and metabolism
- Low incidence of side effects
37
What are the features of IV sedation?
- Requires pulse oximeter monitoring
- Midazolam titrated according to response
- Anxiolytic
- Anterograde amnesia
- Muscle relaxant
- Anticonvulsant
- Minimum effect on cardiovascular/respiratory depression
- No analgesic effects
- Reversal agent - flumazenil
- Requires escort to go home for safety
- Requires cannulation and associated risks
38
What disorders can IV sedation be useful for?
- Epilepsy
- Movement disorders
- Stress related medical conditions
39
What are the side effects of IV sedation?
- Over sedation
- Cardiovascular depression
- Respiratory depression
- Specific drug interactions
- Tolerance – some patients may take diazepam outside of dentistry so may have tolerance
- Sexual fantasy – make sure there are others in the same room who can be a witness
40
What are the advantages of IV sedation?
- Simple to administer
- Rapid onset
- Predictable action/duration
- Rapid recovery
- Rapid metabolism/excretion
- Low incidence of side effects
- Specialised training/monitoring
41
How many trained people should be in the room during sedation?
There needs to be a second appropriate person at all times. A second person trained in sedation is required for sedation to be undertaken, this may be a DN/dentist/anaesthetist. This is for monitoring and as a chaperone.
42
What are the costs due to sedation?
- Materials
- Staff
- Work time lost to patient/escort
43
What are the medicolegal aspects of sedation?
- Written consent
- Escort requirements
- Appropriate post-operative care
44
Where can sedation be undertaken?
- Registered and inspected premises
- With appropriately trained staff
- Appropriate equipment and drugs
45
Why is there a demand for sedation?
- Visiting the dentist is the second most common fear after public speaking (USA 1987)
- Child dental health survey 2013 - 50% moderately anxious, 10% extremely anxious
- The control of anxiety and pain is fundamental to the practice of dentistry - GDC 2002
- Deaths at dentist from GA in practice
46
What are the sedation techniques?
- Inhalation - nitrous oxide/oxygen, sevoflurane
- Intravenous - midazolam, propofol
- Transmucosal - midazolam (intranasal, buccal)
- Oral - temazepam, diazepam, midazolam, ketamine
- Intramuscular - ketamine
- Combination of above
47
Who discovered nitrous oxide?
Horace Wells in 1844. Today people use it recreationally as it is a legal high but there are deaths due to hypoxia.
48
What are the properties of nitrous oxide?
- Volatile
- Denser than air – 1.0:1.5
- Least potent – MAC50 is 104 (minimum amount of gas you need to give somebody for 50% of population to not feel scalpel incision) sevoflurane has a MAC50 of 2
- Often used in anaesthesia as carrier/induction gas
- Poorly soluble – rapid onset/rapid recovery – don’t need a recovery room like you do with IV sedation
49
What are the pharmacokinetics of nitrous oxide/oxygen sedation?
It is inhaled into the lungs with oxygen through a nasal mask. It travels down partial pressure gradient from alveolus to capillaries. It is hardly metabolised - 0.004%. It is excreted through the lungs. The elimination half life is approximately 5 minutes.
50
What are the pharmacodynamics of nitrous oxide/oxygen?
- Analgesic
- Anaesthetic
- Hypnotic
- Anxiolytic - GABA - more relaxed feeling for patient
51
What are the stages of anaesthesia?
1 Analgesia
- A Plane 1 is moderate sedation and analgesia (5-25 N2O)
- Plane 2 - dissociation sedation and analgesia (20-55% N2O) patient can imagine they are somewhere else
- Plane 3 - total analgesia (50-70% N2O) losing consciousness
2 Excitement
3 Surgical analgesia
4 Respiratory paralysis
With conscious sedation we want to be in stage 1. With surgery we would want stage 3, never stage 4. Give 30% nitrous oxide.
52
What are the signs of adequate sedation?
- Awake
- Feels relaxed
- Suggestive state
- Giggling – give more or less as this is not helpful
- Verbal responses
- Maintaining mouth open
- Reduced blink rate
- Spontaneous respiration
53
What are the signs of over sedation?
- Patient no longer enjoying the effects
- Hysterical laughter, tears
- Decreased cooperation
- Nausea/vomiting
- Mouth closing – repeatedly
- Snoring
- Incoherent speech
- Irrational and sluggish responses
- Loss of consciousness
54
What are the indications for inhalation sedation?
```
Social:
- Mild anxiety/needle phobias/gagging/fainting
- To enable cannulation
Medical:
- Conditions aggravated by stress
- Conditions where continuous oxygen delivery is beneficial
- Conditions which affect cooperation
Dental:
- Unpleasant procedures
- Avoid GA in medically compromised
```
55
What are the contraindications for inhalation sedation?
Social:
- Severe anxiety/claustrophobia/no escort
- Lack of understanding
Medical:
- Blocked nose/URTI/unable to nose breathe
- Recent eye/middle ear/sinus/intracranial surgery
- Bleomycin therapy/myasthenia Gravis
- Pregnancy - 1st and 3rd trimesters
Dental:
- Traumatic procedures/unsuitable for LA alone
- Treatment on upper anterior teeth - lip trapped
56
What are the safety features/checks for inhalation sedation?
- Pin index system - tube going from nitrous oxide and oxygen cannot get mixed up
- Scavenging at 40L/minute - removing air at level of nose mask
- Nasal mask and tubing - inner tube to nitrous oxide and oxygen and outer tuber to scavenging
- Oxygen failsafe - if oxygen cuts out the nitrous oxide will also automatically cut out
- Max 70% nitrous oxide and can't give any more than this
- Oxygen flush - delivers 30L of oxygen in a second, not pleasant and only used in an emergency, 35 litres/minute
- Air entrainment valve - if bag goes flat this allows patient to breathe in normal fresh air, check valve is clear
- Reservoir bag needs to be changed on date written on bag as it is made of rubber
- 2 oxygen and 2 nitrous oxide cylinders on each machine
- Colour coded cylinders, tubing and flowmeters
- Diameter index safety system
- NIST pipeline (anti-static, non-compressible, colour coded)
- Touch coded knobs for individual flowmeters
- Pressure regulators 45-55psig
- 30% minimum oxygen
- One way valve in bag/tee
- Conducting tube minimises resistance to gas flow, prevents kinking
- One way valve on expiratory limb
- Scavenging active/passive
57
What are the pre-operative instructions for nitrous oxide?
- Light meal, avoid fizzy drinks
- Take routine medicines as usual
- Children must be accompanied to and form their appointment by a competent adult
- Do not bring other children
- Can cause dizziness/nausea/headaches at higher doses
58
What is the technique for inhalation sedation?
- Safety checks
- Introduce child (giggle gas, happy gas)
- Start O2 and turn up flow rate (5-6L/min)
- Fit mask and encourage nose breathing
- Titrate N2O 10% per minute to 30% and then 5% per min until sedated
- Hypnotic, suggestion, clinical monitoring
- 100% O2 minimum of 3 minutes to recover - preventing diffusion hypoxia (5 minutes in Sheffield)
59
What is diffusion hypoxia?
It was described by Fick 1955 and it is seen in the 10 minutes following the cessation of inhalation sedation. Nitrous oxide is poorly soluble in blood. When you stop giving it the partial pressure reduces in the lungs so the nitrous oxide travels from capillaries to the alveoli rapidly which floods the lungs with nitrous oxide. The rapid elimination of nitrous oxide into the lungs dilutes the oxygen within the alveoli and lowers the alveolar oxygen concentration. This is why oxygen needs to be given. It is responsible for most reports of headache, nausea and lethargy post-operatively. It is prevented by routine administration of 100% oxygen for 3-5 minutes post-operatively.
60
What needs to be recorded in the notes in inhalation sedation?
- Consent and escort
- Safety checks completed
- Second appropriate person (dental nurse)
- Mask size
- Flow rate
- Max dose
- Response/level of cooperation
- Recovery time
61
How do you reduce exposure during inhalation sedation?
- COSHH exposure limits for dentists - 100ppm TWA (time weighted average) over 8 hours
- Active scavenging at 45L/min - statuary requirement in UK, at level of nasal hood
- Passive scavenging - floor level extractor fan, opening window
- Supplementary high volume aspiration
- Rubber dam - inconclusive but seems logical
- Well-fitting mask
- Good technique - reduce mouth breathing/conversation/titrate carefully
- Good initial patient assessment
62
What are the types of occupational hazard with inhalation sedation?
- Reproductive
- Haematological
- Neurological
- Also reports of hepatic disease, renal disease, cytotoxicity, malignancy
63
What are the reproductive risks with inhalation sedation? (chronic exposure)
- Miscarriage - maternal and paternal influences (Cohen et al 1980), twice as likely to miscarry if scavenging not provided
- Reduced fertility in dental assistants working in unscavenged offices for over 5 hours per week (Rowland et al, 1992)
- Possible risk of teratogenesis/teratogenic effects reported
- Increased rate of spontaneous abortion
64
What are the haematological risks with inhalation sedation?
Nitrous oxide oxidises vitamin B12 which inactivates methionine synthase. This impairs DNA synthesis, affecting haematopoeisis. This causes pernicious anaemia.
Bone marrow dysfunction.
65
What are the neurological risks of inhalation sedation?
Methionine is essential for myelin synthesis. This leads to peripheral neuropathy, spinal cord degeneration/myelopathy.
Non-specific neurological disease.
66
What does the cumulative effect in inhalation sedation depend on?
- Pattern of exposure
- Tissue sensitivity
- Vitamin B12 intake and stores
- Extent to which methionine synthase is deactivated
67
What is the evidence for the success of inhalation sedation?
Shaw et al 1996:
- 90% of children aged 4-17 years manage extractions successfully with LA and N2O/O2 sedation
- 97% of parents and children satisfied
68
What is the evidence for the time to sedation with inhalation sedation?
Wilson et al 2007:
| - Takes an average of 7 minutes to reach adequate sedation
69
What is the evidence for the cost of inhalation sedation?
Jameson et al 2007:
- 245.47 per patient for dental care under advanced conscious sedation
- 359.91 per patient under GA
70
What are the advantages of inhalation sedation?
- Non-invasive technique
- Drug level easily altered or discontinued
- Minimal impairment of reflexes
- Drug administered and excreted through the lungs so no metabolism and thus rapid recovery
- No fasting required
- Some analgesia
71
What are the disadvantages of inhalation sedation?
- Lack of potency of nitrous oxide
- Expense of equipment
- Requirement for a clear nasal airway
- Intrusion of nasal mask into operating field
- Patient perception of equipment
- Space occupying equipment
- Chronic exposure of staff
- Potential for staff addiction
- Lack of operator control
72
What patients are suitable for inhalation sedation?
- Patients having unpleasant treatment
- Anxious children/anxious adults
- Needle phobia
- Patients who retch easily
- People with special needs
- Medically compromised patients
73
What are the contraindications for inhalation sedation?
- Respiratory tract obstruction
- Nasal obstruction
- Cyanosis at rest due to chronic cardiac or respiratory disease
- Inability to communicate or cooperate (age, severe learning difficulty)
- First trimester of pregnancy
- Acute fear of the GA mask
- Multiple sclerosis
- Myasthenia gravis
- Claustrophobia
- Severe personality disorders
- Recent ophthalmic surgery using inter-ocular gases
- Any condition where there is air entrapment in the body e.g. myringoplasty, head injury, pneumothorax, maxillofacial injury etc
- Procedures where the mask may interfere with operative work
- Current medication check BNF e.g. methotrexate
74
What problems are associated with ASA III patients for inhalation sedation
- Consultation with medical colleagues advised
- Stable but may deteriorate rapidly
- Deteriorative aggravated by anxiety and stress
- Diagnosis of deterioration difficult particularly under sedation
Treat the patient when they are in their best health.
75
What are the properties of oxygen?
- Discovered 1771 Joseph Priestley
- Clear, colourless, odourless gas
- 20.9% of atmospheric air
- Gaseous when stored in compressed gas cylinders
- 137 bar full cylinder pressure
- Supports combustion
- Cylinders painted black and a white shoulder (UK)
- Relieves hypoxia
76
What are the properties of an ideal inhalation sedation?
- Alleviate fear and anxiety
- Produce a degree of amnesia and analgesia
- Suppress vomiting reflex but not protective reflexes
- Prolong potential operating time
- Be rapidly effective
- Be easily eliminated
- Have no side effects
- Be safely and easily administered by the operator
- Require no special precautions or procedures
77
What are the properties of nitrous oxide?
- Non-irritating, sweet smelling, colourless gas
- Blue cylinders 44Bar
- Gas liquifies under pressure (keep cylinder vertical in use)
- Cylinder contains liquid under pressure
- Cylinder cools in use due to the latent heat of vapourisation
- Supports combustion but not inflammable
- Blood/gas solubility co-efficient 0.47 (insoluble)
- Carried in the blood in physical solution only
- MAC 105% weak anaesthetic
- Strong analgesic
78
What are the systemic effects of nitrous oxide?
- CNS depression of all senses
- CVS (cardiovascular system) slight depression at high concentrations
- RS non-irritant, slight increase in minute volume
- Non-allergenic
- No significant effect on GIT, liver, kidney
- Increases incidence of spontaneous abortion
- Decreases fertility if long exposure?
- Inhibits action of methionine synthetase for vitamin B12 production, can cause impaired bone marrow function
- Thys can affect DNA production and produce pernicious anaemia like effects
- Long term exposure leads to peripheral sensory neuropathy
79
What is MAC?
It is defined as the minimum alveolar concentration of anaesthetic at 1 atmosphere that produces immobility in 50% of those patients or animals exposed to a noxious stimulus. It is a measure of anaesthetic potency. MAC is reduced in the elderly and by other sedative agents. Nitrous oxide 105% isoflurane 1.15% sevoflurane 1.85%
80
How can occupational exposure be reduced?
- Regular servicing of machine and checking by staff
- Vent dental suction out of the surgery
- Minimise leaks from poorly fitting facemasks
- Check flowmeters are not inadvertently left on
- Limit length of appointment
- Use low concentrations where possible
- Take regular breaks
- Use a large room if possible
- Adequate room ventilation, open windows, fans at floor level
- Active or passive scavenging to remove pollution at source
- Encourage the patient not to talk or mouthbreathe
- Use rubber dam
- N2O monitors
- Secure equipment at the end of the day
81
What does evidence show about levels of nitrous oxide in the dental surgery?
o It is difficult to adhere to the recommended levels in this environment even with active scavenging and a scavenging nosepiece
82
How can nitrous oxide be abused?
- Used for pleasurable and recreational purposes since 1772
- Main abusers are professionals with easy access to the drug
- Always keep a cylinder stock record. 1 nitrous oxide cylinder will be used for about 2.5 oxygen cylinders
- Prolonged exposure toxic to rapidly dividing cells peripheral neuropathy, numbness, pain, tingling in extremities, that may be irreversible
- Although nitrous oxide has been legal in the past, since the psychoactive substances act can into effect on 26 May 2016 it is not illegal to supply or import nitrous oxide for human consumption
83
What is the responsiveness, airway, ventilation and cardiovascular effects of minimal sedation?
Responsiveness is normal response to verbal commands, the airway, ventilation and cardiovascular system are unaffected.
84
What is the responsiveness, airway, ventilation and cardiovascular effects of moderate sedation?
Responsiveness is purposeful response to verbal or tactile stimulation. The airway is maintained without intervention. The ventilation is adequate. The cardiovascular system is usually maintained.
85
What is the responsiveness, airway, ventilation and cardiovascular effects of deep sedation?
The responsiveness is purposeful response following repeated or painful stimulation. With the airway intervention may be required. Ventilation may be inadequate. The cardiovascular system is usually maintained.
86
What is the responsiveness, airway, ventilation and cardiovascular effects of general anaesthetic?
The responsiveness is unrousable even with painful stimulation. Intervention is often required with the airway. Ventilation is frequently inadequate. The cardiovascular system may be impaired.
87
What is the basic and advanced monitoring?
- Respiratory rate 10-18 per minute
- Depth of breathing
- Pattern of breathing
- Cyanosis - blue skin
Advanced:
- Pulse oximetry (mandatory)
- Carbon dioxide monitoring (optional)
88
What is pulse oximetry?
Pulse oximetry measures arterial oxygen saturation. It is non-invasive and accurate. A pulse oximeter has a light emitting diode so light goes into the tissues. There is a photodetector on the other side to detect the light that has passed through and is reflected back. The reflected light goes into the computer to give you a number. Red light is 660nm and infrared is 910nm. Oxygenated blood emits red light. Deoxygenated blood absorbs the red light so doesn't emit much. The sensor detects how much red light is emitted. If it is 95 then this is good. 100 is best. Less than 95 is worrying. Below 85 is bad. The number below 85 doesn't mean anything. Pulse oximetry is based of three principles:
- Difference in absorption spectra of reduced and oxygenated haemoglobin
- Beer-Lambert Law
- That only reduces and oxy-haemoglobin are present in the blood
89
What are the pulse oximetry limitations?
- Ambient light
- Movement
- Cold peripheries
- Nail varnish
- Measurement lag
90
What is capnography?
It detects exhaled CO2 in breath. It is usually via nasal prongs. Waveform displayed on a monitor. It allows confirmation of adequate ventilation and an open airway. The patient has to be breathing through their nose.
91
What respiratory complications can be caused by sedation?
- Upper airway obstruction
| - Hypoventilation
92
What is upper airway obstruction?
Sedation leads to a decrease in tone of the muscles of the pharynx. This leads to pharyngeal collapse and the tongue falls back against the back wall of the pharynx. Mild cases lead to partial airway obstruction and more severe leads to complete obstruction which is a potentially fatal complication. May also be due to swelling, tumour stricture, irradiation, epiglottis, restricted jaw opening
93
What is hypoventilation?
Sedative drugs also sedate the respiratory centre in the brain. They also reduce receptor sensitivity to CO2. This leads to reduced respiratory rate or complete cessation of breathing. CO2 levels can build up leading to narcosis. Detection is through monitoring respiratory rate and a drop in oxygen saturation.
94
What are the signs of airway obstruction?
- Snoring
- Stridor
- May lead to coughing, straining, vomiting, regurgitation
- Paradoxical chest and abdominal movement, straining
- Drop in O2 saturations
- Loss of CO2 trace
- Seesaw respiration
95
What is the management of airway obstruction?
- Supplementary oxygen
- Careful titration of sedation
- Basic airway opening manoeuvres
- Airway adjuncts
Airway opening manoeuvres are jaw lift. Airway adjuncts include oropharyngeal airway and nasopharyngeal airway.
96
What is hypoventilation management?
- Reversal of sedation with flumazenil or naloxone
| - Assisted ventilation with self-inflating AMBU bag
97
What are the basic and advanced cardiovascular system monitoring?
```
Basic clinical signs:
- Heart rate (from pulse oximeter)
- Heart rhythm
- Conscious level
- Skin colour
- Capillary refill - press on forehead for 5 seconds and release (about 2 seconds for normal, more than 5 needs help)
Advanced:
- Non-invasive blood pressure (mandatory)
- ECG monitoring (optional)
```
98
What is non-invasive blood pressure?
NIBP are automated machines. There is a cuff around arm or calf and automatic cycling every 5 minutes. This is affected by movement and wrong size cuff. The baseline should be within a normal range for age and physical status and this is taken in the assessment. Manual sphygmomanometer, electronic sphygmomanometer, calibrated and serviced.
99
What is ECG monitoring and when is it used?
It should be used in patients with a history of significant cardiovascular disease. It can detect arrhythmias and also signs of cardiac ischaemia and infarction. It is usually a 3 lead configuration.
100
What are the cardiovascular complications?
- Hypotension
- Cardiac arrhythmias
- Cardiac arrest
101
What are the hypotension causes in sedation?
Vasodilation is caused by sedative drugs. Some drugs decrease the strength of heart contraction. It is dose related. It is more likely to occur in the elderly and those with existing cardiovascular disease.
102
What is the treatment of hypotension?
- Prevention better than cure
- Pre-assessment of comorbidity
- Stop administering agent
- Place patient head down and with feet elevated
- IV fluids may be required
103
How does sedation cause cardiac arrhythmias?
- Multi-factorial aetiology
- May be precipitated by adrenaline in LA
- More likely in elderly and those with CVS disease
- Raised blood CO2 levels also increase risk
Call for expert help and look at ALS standard algorithms in notes.
104
What is the treatment of cardiac arrest?
If unresponsiveness, not breathing or occasional gasps call resuscitation team. Start CPR 30:2. Attach defibrillator/monitor. Minimise interruptions. Assess rhythm and if shockable 1 shock and immediately resume CPR for 2 minutes. If non-shockable immediately resume CPR for 2 mins.
If return of spontaneous circulation post cardiac arrest treatment:
- ABCDE
- Controlled oxygenation and ventilation
- 12 lead ECG
- Treat precipitating cause
- Temperature control/therapeutic hypothermia
105
What is the purpose of sedation?
- Control of fear, anxiety and apprehension
- Reduce stress associated with unpleasant/painful procedures
- To control severe gag reflexes
- Treatment of uncooperative patients including children and those with disabilities
- To stabilise the blood pressure of patients with hypertension and a history of cardiovascular or cerebro-vascular disease
106
What are the advantages of intravenous sedation?
- Given remote from operating site
- Administered as a single dose
- Rapid onset
- Mouth breathing not important
- Patient cooperation less important
- Sedation attained pharmacologically
- Excellent amnesia
- No pollution - people breathing it out into the room
107
What are the disadvantages of intravenous sedation?
- No clinically useful analgesia
- Overdose can leas to profound respiratory depression
- Laryngeal reflexes obtunded for a short period
- Occasional disinhibition effects
- Occurrence of sexual fantasies
- Pre/post-operative instructions must be followed
108
What are the patient management techniques for anxiety?
- Time and TLC
- Local analgesia
- Psychotherapy
- Hypnosis
- Acupuncture
- Inhalation sedation
- Oral/transmucosal sedation
- Intravenous sedation
- General anaesthesia
109
What is the American Society of Anaesthesiologists physical status rating?
I - normal healthy patient
II - a patient with mild to moderate systemic disease
III - patient with severe systemic disease that limits activity but is not incapacitating
IV - a patient with severe systemic disease that is incapacitating and is a constant threat to life
V - a moribund patient not expected to live 24 hours with or without operation
110
What dental history information should you obtain from the patient prior to sedation?
- Attitude to dental care
- Past history
- Past history of sedation and GA
- Recent history
- Main dental problem
111
What social history should you obtain prior to sedation?
- Able to provide responsible escort
- Ability to understand and follow pre- and post-operative instructions
- Someone to help at home
- Able to take time of work
- Someone to look after the children
- Someone to stay overnight
- Transport to and from the surgery
112
What is informed consent?
Explain the benefits of treatment, the risks and disadvantages of treatment and the treatment alternatives to the patient in a language that they understand. Document for each course of treatment.
113
How should you manage patients who lack capacity to give consent?
- Discuss everything with next of kin
- Discuss treatment with care staff
- Have 2 professionals (doctor/dentist) independently agree that this treatment is in the best interests of the patient
- Named person to sign pre/post operative instructions
- Liase with parents/GP regarding medical history
- Appoint IMCA
114
What is the baseline physical assessment prior to IV sedation?
- Colour
- Pulse
- Respiration
- Arterial oxygen saturation
- Blood pressure
- Weight
- BMI
- Level of consciousness
- Degree of understanding and co-operation
Special tests e.g. liver function test, ECG, sickle cell test, FBC, INR, clotting screen.
115
What are the clinical effects of benzodiazepines?
- Anxiolysis
- Sedation
- Hypnosis
- Amnesia
- Anticonvulsant
- Decrease in skeletal muscle tone
116
What are the contraindications to IV sedation?
- Allergy to benzodiazepines
- Pregnancy
- Age
- ASA III, IV, V
- Poor veins
- Drug interactions – download BNF app
- High or very low BMI
- Respiratory depression
- Acute pulmonary insufficiency
- Sleep apnoea syndrome
- Severe hepatic impairment
117
Name some medications that can interact with IV sedation?
- Clarithromycin
- Erythromycin
- Fluconazole
- Verapamil
- Phenytoin
- Rifampicin
- Antihistamines
- Antipsychotics
- Baclofen
- Beta blockers
- ACE inhibitors
- Anaesthetics general
- Angiotensin II receptor antagonists
- Tricyclic antidepressants
- Calcium channel blockers e.g. diuretics, methyldopa, nitrates, opioid analgesics
Often get patient to stop taking opioid analgesics to make sure there is no respiratory depression. Know own limitations if in doubt refer. Look at notes.
118
What equipment is needed for IV sedation?
- Midazolam, note expiry date/batch keep ampoule – 5mg/5ml (1mg/ml)
- Saline for intravenous injection 2x5ml syringe
- Straight filter needle for drawing up drug
- Pre injection swap/mediwipe
- Tegaderm patch to secure cannula
- 22G cannula
- Gauze/ampoule opener
- Yellow sharps box
- Tourniquet
- Needles, syringes, cannula, tape, alcohol wipe
- Flumezenil/anexate 0.5mg/5ml (100mcg/ml) is the reversal agent
- Oxygen and emergency oxygen
- Suction, emergency suction, non-mains powdered suction, attachments for oral and pharyngeal suction
119
What oxygen should be in the surgery for IV sedation?
- Oxygen and emergency oxygen
- Cylinder capable of giving 15 litres per minute
- Attachments capable of administering IPPV
- Within ‘arms reach’
- Checked each session
- Records kept
120
What are the normal values for IV sedation?
- Weight - 70kg
- Temperature 36-37.5 degrees celsius, 96-8-99.4F
- Colour - pink, well perfused, check gingivae, nail beds
- Pulse - 70 beats per minute, full volume, regular
- Rate
- Rhythm - regular, irregular
- Volume - strong, weak
- Respiration - 12-20 regular breaths per minute
- Type - shallow, deep
- Quality - obstructed, unobstructed, bilateral
- Blood pressure - 120/80mmgHg 16/10KPa
121
How can you assess level of consciousness in IV sedation?
- Stand unaided with eyes closed
- Romberg test
- Touch nose with forefinger
- Loss of facial expression/animated
- Eye open/closed/ptosis
- Speech slurred/slow
- Respond to verbal command
122
What are the types of transmucosal sedation?
It is not done very often.
- Sublingual
- Rectal
- Intranasal
123
What are the features of transmucosal sedation?
It avoids venepuncture. There is rapid absorption and rapid onset. The drug directly enters systemic circulation and bypasses the enterohepatic circulation. You need good patient cooperation. It avoids pollution. Blood levels are significantly higher than after oral administration. Once administered, effects cannot be terminated or switched off.
124
What is transmucosal midazolam?
- Very bitter taste
- Acidity, ph 3.5, causes stinging intra-nasally
- Use concentrated formulation
- Studies used 0.2-0.5mg/kg for premedication and sedation in children
125
What sedative drugs can be given orally?
- Temazepam
- Midazolam
- Diazepam
- Nitrazepam
126
What are the advantages of oral sedation?
- Administered as a single dose
- Given remote from operating site
- Mouth-breathing not important
- Patient cooperation less important
- Pharmacology rather than psychology
- Good amnesia
- No pollution
- No venepuncture required
127
What are the disadvantages of oral sedation?
- Slow onset, uncertain effect
- No clinically useful analgesia
- Once administered effects cannot be discontinued or switched off
- Dose is estimated rather than titrated
- Occasional dis-inhibition effects
- Pre and post operative instructions need to be followed as for intravenous sedation
- Same staffing/equipment/training requirement as for intravenous sedation
- Some drugs cause gastric irritation
128
What is midazolam for injection?
It is a clear, colourless isotonic solution (not painful on injection) containing:
- Sodium chloride
- Hydrochloric acid
- Sodium hydroxide in water for injection
- Ph 3.3
- Liquid soluble at physiological ph
129
How does IV midazolam work?
It works on GABA receptor in CNS (sedation causing). Benzodiazepines enhance the inhibitory action of GABA in the CNS. BZD potentiate GABA by increasing the flux of chloride ions into the cell thus decreasing the ability of the cell to initiate an action potential. Benzodiazepines increase the action of GABA by binding to it and then the receptor.
130
What substances affect GABA A?
GABA A is modulated by:
- Benzodiazepines
- Barbiturates
- Some steroids
- Alcohol
- (synergistic effects)
131
What is GABA B?
It has a skeletal muscle role.
132
What is the effect of GABA A modulation?
Opening of receptor channels cause chloride ion influx. This causes:
- Anxiolytic effect
- Hypnotic effect
- Anticonvulsive
- Amnesic effect
- Muscular relaxation
133
What are the pharmacokinetics of midazolam?
- Elimination half life is 1.2-8 hours
- Onset of action
- IV 3 mins
- IM 5 mins
- Oral 15 minutes
- Nasal 15 minutes
- Rectal 15 minutes
134
What factors affect half life?
- Age - increased in elderly
- Sepsis
- Poor renal function
135
What are the additional effects of IV midazolam?
- Decreases ventilatory response to increased CO2
- Decreases mean arterial pressure
- Reduction of cerebral blood flow
136
What are the contraindications of IV midazolam?
- Hypersensitivity to benzodiazepines
- Myasthenia gravis
- Shock or vital sign depression
- Acute narrow angle glaucoma
- Open angle glaucoma with app rx
- Ask treating physician
137
When should care be taken with midazolam?
- Benzodiazepine use
- Opiates
- Alcohol use
- Other sedatives
- Social drugs - patients often not willingt o admit to this (especially if person with them)
- Interactions with other medications - be aware and see BNF
- Respiratory depression
138
What are the overdose signs of IV midazolam?
- Oversedation
- Confusion
- Impaired coordination
- Diminished reflexes
- Decreasing vital signs/O2 sats
If so stop midazolam, oxygen, reversal with flumazenil 200ug in initial dose.
139
What are the pharmacokinetics of flumazenil?
Flumazenil is used to reverse benzodiazepine effects quickly. Use a dose of 200mcg every 1-2 minutes as required. It acts on GABA receptors to reverse. Onset within 1-2 minutes, peak effect within 6-10 minutes. The dose is 200-600ug IV. It is a competitive inhibitor of BZP. The elimination half life is 53 minutes. Potential for re-sedation due to differences in half life.
140
Do patients need to starve prior to IV midazolam?
There is no necessity to starve a patient for IV midazolam – conscious sedation. Some dentists and anaesthetics do ask the patient to starve. CCDH policy is 2 hours starve prior to IV midazolam sedation.
141
What is the management of accidental arterial access with the cannula?
If it is pre-drug admin then remove cannula and apply pressure.
If it is post-drug admin then leave cannula in place and contact local vascular surgeons urgently.
142
What are the risks with cannulation?
- Transfixation
- Haematoma
- Embolism, types of embolism are thromboembolism, cannula embolism and air embolism
143
What are the adverse incidents with cannulation?
Adverse incidents are when something occurs that is not expected or normal and often results in injury to the patient whether this is direct or indirect. They include:
- Puncture of an artery
- Damage to nerve, tendon, ligament, limb
- Blockage of cannula
- Needlestick injury
144
What are the sequelae and interventions that may be required after IA injection of diazepam, midazolam and temazepam?
Midazolam has no initial symptoms and later symptoms are resolve without sequelae. IA diazepam can lead to phlebitis, vascular impairment. Interventions can be amputation.
The sequelae of IA temazepam can be myocyte necrosis and interstitial oedema. The potential interventions can be fasciotomies, amputations.
145
What is the monitoring for IV sedation?
- BP, HR, O2 saturation
- BP is required pre and post treatment and can be continuously monitored
- O2 saturation required throughout
- Observation of patient vital signs
146
What patients should supplemental oxygen be considered for?
- Epilepsy
- IHD
- Previous CVA
- Heart failure
- Anaemia/sickle cell trait
147
What is important with preparation of IV drugs?
- NPSA guidelines on preparation and administration of drugs for injection
- Sterility
- Labelling
- Disposal
- Recording
148
Does IV midazolam cause analgesia?
It has no analgesic properties so LA is required, however suggestion can be powerful.
149
How is midazolam given IV?
It is given intravenously for moderate sedation. Titration:
- Slow IV administration of 2mg
- Wait 90 seconds and assess sedation
- 1mg
- Wait 90 seconds and assess sedation
- 1mg
- Until desired sedation achieved, desired end point is usually slurring of speech
- Usually no more than 5mg
150
How long does IV midazolam last and what is the dose?
Midazolam sedation has ‘golden 20 minutes’. Another 30 minutes possible but may require top ups. Realistic treatment in time. The dose range is 2-10mg usual.
151
When is the dose of IV midazolam adjusted?
Decrease initial dose to 1.5mg in elderly (up to 3mg). If used with a pre-med then reduce dose by 1/3.
152
What are the complications with IV sedation?
- Falling sats
- Under/over sedated
- Venepuncture related - failed, bruising, extravasation
153
What is the recovery and discharge for IV midazolam?
- Monitor whilst recovering
- Keep one hour after last IV dose of midazolam
- Written and verbal post-op instructions to escort
- Rhomberg
- Steady on feet/walk unaided
154
What are the post-operative instructions for the 24 hours after IV midazolam?
- No driving/operating machinery including cooking, ironing etc
- No alcohol/sedative drugs
- No legal responsibilities including signing legal documents, looking after children, attending work
- Patient not to be left alone
155
What should be recorded after IV sedation?
- Keep accurate contemporaneous notes
- Have a log of all medications used
- Dispose of unused midazolam properly and witnesses
- Record any flumazenil use
- Regularly check drugs – expiry dates
156
What is an unusual side effect of IV sedation?
Sexual fantasy is thought to occur in 1 in 200 cases of midazolam sedation.
