SA Flashcards
Define conscious sedation and general anaesthesia
- reducing or stopping physiological responses without loss of consciousness, cooperation or protective reflexes. Used to ease discomfort/ stress/pain/anxiety
-depresses the CNS
-verbal contact remains
-GA= absence of sensation, without the ability to maintain physiology function such as breathing and protective reflexes. Carried out in hospital setting
What drugs is used for conscious IV sedation and its dose. What is its reverse drug
-midazolam 5mg/5ml (3mg total usually over 3 mins)
0.5mg - sedated, 25g anaesthetised
-flumazenil - IV, 200ug initially, 100ug/min, 1mg max (only used in emergencies, not speeding up recovery)
Indications/ Types of patients that benefit from sedation
*Moderate dental anxiety/ phobias
*Children - Used more routinely as part of behavioural management (eg. if uncooperative)
*Medically compromised patients - Stress precipitates conditions e.g. asthma, angina, hypertension
*Special needs patients -poor cooperation with mild learning disability, cerebral palsy, Parkinson’s etc.
*Other movement disorders
*Poor Gag and swallow reflex
*Persistent fainting
*Traumatic dental procedures (MOS, implants)
Contraindications for IV sedation
-Allergy
-Unwilling/uncooperative
-Unaccompanied- no escort available
-Very old - liver and kidney affects metabolism
-Children<12 -Sensitive to dosage with young people. Restless in chair (opt for GA as safer)
-Severe psychiatric disease
-Severe or uncontrolled systemic disease- e.g. recent MI, COPD
-Hepatic or renal insufficiency -Won’t metabolise the drug
-Pregnancy and breastfeeding
-severe needle phobia
-poor veins
-methotrexate?
-high BMI (if >36) or sleep apnoea- done in hospital)
-responsibilities- caring for children
-recent alcohol or rec drugs
Contraindications for RA sedation
-poor nasal airway- heavy cold, deviated septum
-Claustrophobic patients
-Middle Ear/Sinus Infection (nitrous oxide can go into air filled cavities and increase pressure in these areas)
-Certain types of occular surgery
-Behavioural problems/Personality disorders, poor cooperation
-URTI
-Severe anxiety
-1st trimester of pregnancy (if essential then do 2nd trimester and 30% max)
-Methotrexate?
-Bleomycin therapy
-COPD
What affect does methotrexate have with nitrous oxide
The drug Causes depletion of folate. With nitrous oxide can cause dangerous low levels of folate
Why bleomycin sulphate is contraindicated with nitrous oxide
- anti-neoplastic therapy
- due to the increased incidence of pulmonary fibrosis and other lung diseases.
- predisposed to respiratory failure following exposure to high concentrations of oxygen over 25%.
-Since use of 100% oxygen is part of the standard sedation procedure (in both the initial and recovery phases) there is an increased risk of possible problems in these patients.
Where does metabolism and excretion of IV and inhalation drugs occur
-IV: liver metabolism, kidney excretion
-RA: small metabolism in liver. Excretion in lungs
Types of drugs that increase risk of respiratory depression and drop in BP with midazolam
-Antihypertensives= HUGE DROP IN BP
-ritonavir (antiviral) = extreme risk of respiratory depression
What is included in patient assessment before sedation (RA and IV) Instructions given to pt
-suitability (why it is needed)
-record baseline HR, BP, respiratory rate, BMI, oxygen saturation
-give instructions. Discuss risks
- MH
-gain written consent
-check understanding of procedure
-explain they need an escort home (only for IV), light meal before hand, no alcohol or rec drugs prior (synergistic effect)
-ask if had previous sedation (can help indicate how much to give)
What is the ASA classification system
-American Society of Anaesthesiologists
-Classification based on physical status
-Allocation of patients to grades according to:
o Medical status
o Operative/anaesthetic risk
-Estimation of fitness for sedation or GA
- I to V
What is ASA I. What is their BP
-patient without systemic disease; a normally healthy patient
-minimal anxiety
<60 years old
< 140 / 90 BP
What is ASA II
-MILD systemic disease - well-controlled (asthma, non-insulin diabetes, anaemia)
-very phobic, overweight (BMI 30-40), pregnant, special needs, drug allergy, smoker, alcoholic
-OR any healthy patient >60 years old (slower physiology)
< 160 / 95 BP
What conditions fit in the classification of ASA III.
-MODERATE systemic disease; which limits function but is not incapacitating
-poorly controlled insulin diabetes, epilepsy, angina, COPD, asthma etc
-Chronic bronchitis or emphysema
-Congestive heart failure or thyroid disease
< 200 / 115 BP
BMI>40
What is ASA IV
INCAPACITATING SYSTEMIC DISEASE; which is a constant threat of life
- sepsis, ongoing cardiac ischemia
-<3 months Post MI or CVA or TIA or stent
-COAD or CHF requiring O2 therapy
-Uncontrolled dysrhythmias
-Blood pressure > 200 / 115
What is ASA V and VI
5=moribund patient not expected to survive 24 hours unless treated. Needs surgery
6= brain dead
Why someone with insulin dependant diabetes (type I) is at risk during sedation
-likely will go hypo as cannot eat the morning of sedation however will still take insulin = glucose stores will be depleted rapidly and pt becomes hypo – difficult to tell this is happening when sedated
Which ASA classifications (I-V) are suitable for sedation in a GDP
*ASA I = Suitable for sedation in GDP
*ASA II= Suitable for sedation in GDP; with appropriate precautions
*ASA III= Increased risk > usually refer to hospital
*ASA IV / V = Life-threatening disease = must be treated in hospital (should be by an anaeshtetist)
Indications for cannulation in dentistry
1.IV drug administration
-Prophylaxis (antibiotic/steroid cover)
-Medical Emergency
2. IV sedation
Sites for cannulation. Pros and cons for each
- Dorsal veins of the hand
-Easily visible, superficial veins. No vital structures - Antecubital fossa (basilic, cephalic, median cubital veins)
-Large veins
-Danger of brachial artery & median nerve
-Problems with joint movement
Step by step technique of cannulation
-Draw up 0.9% saline into 5ml syringe
-Select 22g venous cannulae & check its working order
-Select an appropriate vein.
-Apply tourniquet, 10cm above cannulation site
-Wait for vein to become engorged (hand clenching, tapping vein)
-Alcohol Wipe surface
-Tense skin & insert cannula at an angle of 10-15 degrees through skin and into the vein
-A 1st flash-back of blood at white cap end indicates the cannula has entered the vein
-Withdraw the metal needle slightly (0.5cm) so can see needle end and flashback
-Advance cannula up to its hub
-Remove tourniquet
-Remove metal insertion needle & place end cap – be quick
-Secure cannula with tape & administer 2-5ml 0.9% saline into injection port (if lump appears then cannula is subcutaneous > so remove & resite)
-5mg in 5ml drawn into 5ml syringe. Injected 1mg every 1 minute
Complications that can arise during cannulation and how to overcome
1.Difficult Veins
=Be patient
2.Extra-venous Cannulation
-Pain on cannulation
-Formation of subcutaneous lump
=Resite cannula
3.Intra-arterial Injection
-Significant pain, bright red pulsatile blood
=remove needle, apply pressure (+/- refer)
4.Haematoma Formation
-Avoid multiple venepuncture
-Avoid penetrating opposite wall of vein
=apply Pressure after cannula removed
5. Pain in arm, fingers, back of hand
IV sedation procedure
-Cannulation
-Record arterial oxygen saturation (>97%) Respiratory rate, HR, BP every 5 mins
-Draw up midazolam 5mg/5ml in 5 ml syringe
-1mg injected slowly. Wait 1 minute. Then 1mg every minute thereafter
-Slow titration against to patient effect
-Flush with saline to make sure all in system
-Commence dental treatment
-continue to monitor: responsiveness, colour, clear airway, O2, RR, HR, BP
Why administer midazolam in increments
1mg over 1 minute (sometimes 0.5 mg if history of fast effect)
So you can monitor the patient while it takes effect as it take 40 seconds to get to brain
Signs of sedation
-Slurring and slowing of speech
-Relaxed appearance
-Delayed response to commands
-Ptosis – drooping of upper eyelids
-Willingness to undergo treatment
-Feeling warm and tingly
Things to check before discharging patient after IV sedation
-Monitor arterial oxygen saturation for at least 1 hour after last increment (>97%)
-Discharge: at least 1 hour after last increment, with escort, can walk in straight line, satisfactory BP and oxygen saturation
-written and verbal POIG: no drinking, driving, signing legal docs, operating machinery, sole carer for children for 24 hrs
Complications of IV sedation
-Respiratory depression: due to reduced arterial oxygen saturation
-Over-sedation
-Disinhibition – react in complete opposite way to expected= Uncooperative/ aggressive/ violent
-Medical emergencies (epilepsy seizure won’t occur)
-Allergy to midazolam
Signs of oversedation. What to do if oxygen saturation drops during sedation
=over sedation, respiratory depression. Signs=nausea, headache, vomitting, loss of consciousness
-Get patient to take deep breaths, tilt chin back and opening airway.
-If <94%: Supplement oxygen can be given - 3l/min
-If <90% then use faster flow of oxygen in mask
-Or if this does not work use flumazenil (reversal)
Can you use sedation if pregnant or breastfeeding
If pregnant:
-No IV: can affect the baby
-No RA as can affect baby. If essential then in 2nd trimester as in 1st it can cause developmental issues and 3rd it can cause preterm birth
If breastfeeding:
-RA fine as out of system immediately
-Avoid IV, but can do if for 24 hours using formula or use pumped milk
-can’t be is same room as someone getting RA
Differential diagnosis of loss of consciousness
-Vasovagal attack (faint)
-Over-sedation
-Cardiac arrest – no pulse/ not breathing
-Hypo-glycaemia – if pt has insulin but no breakfast – MH IMPORTANT
-Adrenal crisis
-Cerebrovascular Accident - stroke
-Epileptic seizure
Signs and symptoms of vasovagal syncope
=Vasodilation in vessels going toward skeletal muscles – BP drops. Not enough Cardiac output to maintain blood to brain
-Cause - anxiety, pain, fatigue, fasting
Signs and symptoms:
-Nausea, pallor
-Sweating
-Pulse - weak/thready. rapid (conscious) then sudden slow (unconscious)
-Sudden loss of consciousness
-Fits & cyanosis
Management of vasovagal syncope
-Supine + raise legs (ALLOWS BLOOD TO RUSH BACK TO BRAIN)
-Glucose drink & reassurance
-Oxygen (10 litres per min)
-Monitor breathing & pulse
-If recovery not rapid (within 1-2 mins), re-consider diagnosis
Signs and symptoms of hypoglycaemia
-Cause: poorly controlled diabetes, Missed meal but has insulin, Infection, Fever
Warning (adrenergic signs):
-Irritable/uncooperative = less compliant with dental treatment
-Hunger, dry mouth
-tremor
-palpitations, sweating
Established signs:
-Drowsiness/ disorientation
-confusion
-aggression
-slurred speech
-Gradual loss of consciousness
Management of hypoglycaemia
-Confirm glucose level (< 4 mmol/l)
-If Conscious = glucose/dextrose drink or tablets/gel - 20g
-If Unconscious = glucagon 1mg IM. Takes 10-15 mins to work + oral glucose once conscious
-Oxygen & monitor (glu >5mmol/l)
-Paramedics to check pt afterwards – pt will feel very sleepy afterwards
Differential diagnosis of acute chest pain. And breathing problems
-Stable angina
-Acute coronary syndromes (unstable angina and MI) – persists with GTN
-GORD
-Pleuritic pain
-Pulmonary embolism
-Musculoskeletal
-Panic attack
-Asthma attack
-Anaphylaxis
Causes of stable angina, signs and symptoms
-Reversible Myocardial ischemia -coronary artery blocked with atheroma, not enough O2 gets through when heart is stressed
Signs:
-Severe retrosternal pain (behind sternum) on exercising or stress
-May radiate down left arm and jaw
-Regular pulse
Management of stable angina attack
-Glyceryl trinitrate (GTN) spray (400ug) – this treats it, unlike MI
-Sublingual – if swallowed, will go to liver and 90% will be broken down ASAP
-Repeat every 5 mins, up to 3 times
-Oxygen (10 litres per min)
-Monitor = if no relief, consider possibility of MI
Signs and symptoms of acute coronary syndromes (unstable angina and MI)
*Causes
-Fissure of atheromatous plaque=Coronary occlusion
=Sudden ischaemia =Irreversible damage to heart muscle
*Signs
-Crushing retrosternal pain at rest
-Death-like appearance
-Breathless, vomiting, distress
-Weak, irregular pulse, loss of consciousness, potential cardiac arrest
Management of unstable angina or MI
-Comfortable position
-Oxygen
-Call paramedics
-GTN Spray
-Nitrous oxide 50% with oxygen 50% (if available) – same analgesic effect as MORPHINE & it causes vasodilation
-Aspirin 300mg orally
-Monitor for cardiac arrest
Signs and symptoms of asthma. Exacerbating factors
Exacerbated by anxiety, Stress, Exercise, Infection, Allergy, cold air, pollen
-Breathlessness
-Cannot form sentences
-High RR>25
-Wheezing on expiration/ cough
-Tachycardia >110
-Accessory muscles of respiration
Worrying sings= bradycardia, cyanosis, low RR, confusion, exhaustion, decreased level of concsiousness
Management of asthma
-Sit upright
-2 puffs Salbutamol inhaler +/- spacer (100ug/puff) every 10 mins up to 10 puffs
-Oxygen (10 litres per min)
-Call paramedics (if no improvement or status asthmaticus)
Cause of anaphylaxis. What type of hypersensitivity is it
-Immediate type I hypersensitivity reaction
-Exposure to antigen in a sensitised individual
-Antigen > attaches to IgE antibody on eosinophils & mast cells > degranulation & release of mediators
=Bronchospasm, vasodilatation, oedema, hypotension
Signs and symptoms of anaphylaxis
-Facial flushing (vasodilation)
-Oedema
-Acute breathlessness (bronchospasm)
-Weak/ impalpable pulse (Severe hypotension)
-Loss of consciousness
-rash that blanches
Management of anaphylaxis
-Supine and raise legs
-Adrenaline 1:1000 0.5ml (0.5mg) IM – NEVER IV
-If required repeat after 5 mins
-Oxygen
-Call paramedics
List guidelines for conscious sedation
IACSD 2015
SDCEP 2017
Indications for GA in dentistry
Routine extractions:
* Where LA/sedation has failed
* Acute infection
* Multiple primary extraction in very young patients
* (usually Not for orthodontic extractions)
Complex extractions – surgical extractions, full clearance
Routine dental treatment in special cases -Severe learning difficulties or movement issues
Safety features incorporated into the inhalation sedation equipment. What is the minimum oxygen level that should be given
-colour coding (NO is blue, Oxygen is white)
-oxygen fail safe - nitrous oxide automatically cut off if oxygen run out
- oxygen flush- if pt feeling over sedated
-reservoir bag- Ensures patient is breathing correctly – easy to visualize
-minimum oxygen percentage of 30%
-Air entrainment valve: If gases run out the valve will open and allow patient to breath air
-gas pressure dials
-active scavenging system - vacuum to limit gas released into atmosphere
-one way valve
-emergency cut off
How often is RA equipment serviced
6 monthly/yearly service
Daily checks before use- check bag inflates, correct flow rate, tubes connected properly
Explain inhalation sedation
-A semi-hypnotic technique of conscious sedation in which nitrous oxide and oxygen produce physiological changes to alleviate anxiety so that the patient can co-operate sufficiently to allow dental treatment to take place
-The patient should remain conscious and co-operative through out with all vital reflexes intact. Should be able to communicate throughout
Advantages of inhalation sedation over IV
-Rapid absorption and onset: 2-3 minutes for clinical signs
-Rapid peak action: 3-5 minutes
-Depth of sedation easily regulated
-Duration of sedation flexible
-Rapid elimination and recovery: 3-5 minutes on 100% oxygen
-Moderate analgesia effect
-Non-invasive-No injection
-Few side effects
-Drug not metabolised
-No adverse effects on the liver, kidneys, brain, cardiovascular system or respiratory systems
-Don’t need an escort (unless child)
-children react more predictably than IV so best option
Disadvantages of RA
-Cost of equipment
-Space occupying equipment
-Not a potent agent
-A degree of co-operation is necessary- breathing through nose
-Possibility of chronic exposure
-drug must be administered continuously
-mask may get in way of treatment
Pre-op instructions for RA
-A light meal 2 to 4 hours before appointment
-Children must be accompanied by a responsible adult and be supervised for rest of day
-Adults don’t need escort
-Transport home in car or taxi
-Children should not ride bikes, drive vehicles or operate machinery for the rest of the day
-If have a cold, ask if can breath through nose fine
-Pregnant mums or other children not allowed in room
Step by step technique of RA administration
-Set dial to 100% oxygen
-Settle patient in the chair
-Turn on oxygen at a rate of 4-6L/min
-Ask patient to place nasal hood on nose, ensuring good seal and breathing through nose
-Continual reassurance: explain they are in warm sunny place with tingly hands and feet
-Turn dial to 90% oxygen, 10% nitrous oxide
-After 1 minute turn dial to 80% oxygen
-Continue 5-10% increments every minute until suitable level of sedation
-20%-50% nitrous oxide commonly allows good sedation
-If bag over inflated – reduce flow rate and vise versa
-Commence treatment
-When treatment complete switch to 100% oxygen
-Breath for 2- 3 minutes (to prevent Diffusion Hypoxia)
-Remove nasal hood & sit patient up, check not dizzy
-Discharge home with post-op instructions
Causes of failure of RA technique
Nasal obstruction
Patient mouth breathing
Inefficient seal of nasal hood
Extreme anxiety
Fault in machine
Management of RA over-sedation
Oxygen flush
Reduce nitrous oxide by 5 to 10%
Reassure patient
Monitor patient
Continue or postpone treatment
Options if patient has large needle phobia and is very anxious
Ask what in particular about needles they don’t like- the sight, the feel etc and can work around it
-RA + IV
-nasal sedation (midazolam) + IV
-Oral pre-med (temazapam 10mg tablet or solution)
-Surface anaesthesia 1hr pre
-GA
Action of benzodiazepine
-act on neuronal membrane within the brain and spinal cord
-act on GABA receptors which are inhibitory. More permeable to chloride ions and increase firing. Prolongs time it takes for re-polarisation. During this refractory period no further electrical stimuli can be transmitted across the synapse
-sensory messages are reduced
-produces pharmacological sedation, anxiolysis,
amnesia, muscle relaxation and anticonvulsant effects. Minimal cardiovascular depression
-flumazenil is an antagonist as has greater affinity for the benzodiazepine receptor than the active drugs and therefore displaces
them.
What is the half life of midazolam
1-2 hours
