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56 Cards in this Set

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Name 10 important components of an anaesthetic history
1. General Health: exercise tolerance, cardiac risk
2. Systems review, PMHx, Medications
3. Previous anaesthetics, complications and family with complications
4. EtOH and smoking
5. Other recreational reugs (HIV and HepC)
6. Dentition (loose teeth, bridgework and crowns), obesity and mental status
7. Allergies and drug sensitivities
8. Gastric reflux and hiatus hernia symptoms
9. Hx of thromboembolic disease
10. Fasting status
What familial disease can cause adverse anaesthetic reactions and how?
Malignant hyperthermia.
It increases skeletal muscle oxidative metabolism in response to volatile gas anaesthetics and suxamethonium.
It overwhelms the body's capacity to supply oxygen, remove carbon dioxide, and regulate body temperature, eventually leading to circulatory collapse and death. Also rhabdomyolysis.
What are the fasting guidelines prior to surgery?
Minimum fast for clear liquids: 2hr
Breast milk: 4hr
Light meal, infant formula and other milk: 6hr
What are the anaesthetic implications of a history of gastro-oesophageal reflux?
- Preferrably use and ETT (not LMA)
- If severe reflux (can't lie flat), give antacid prophylaxis, but might risk a difficult intubation
How would you manage cardiac meds in a patient presenting for surgery?
Beta-blockers, Ca2+ channel blockers and nitrates should be continued
How would you manage antihypertensive meds in a patient presenting for surgery?
Should be continued but some prefer to omit ACEi or ATII receptor blockers
How would you manage oral hypoglycaemics in a patient presenting for surgery?
Omit on morning of surgery
How would you manage insulin injections in a patient presenting for surgery?
Continue but at 1/2 dose on morning of surgery
How would you manage regular opiates in a patient presenting for surgery?
Continue
What are the methods of induction of general anaesthesia?
IV- rapid, pleasant. IV access whilst awake
Inhalational- no IV access req'd whilst awake. Easier to control and reverse (e.g. in airway obstruction). Slower, confusion, agitation.
(IM- ketamine)
What anaesthetic agents are used to maintain anaesthesia?
Sevoflurane, desflurane (although not solely as it can induce a sympathetic response)
N2O if <2hrs and simple procedure
What are the advantages and disadvantages of using nitrous oxide?
Advantages: Can use less volatile gas (important in someone frail or with e.g. heart failure)

Disadvantages: Increased PONV, inactivates the cobalamin form of vitamin B12 by oxidation, esp. in elderly (peripheral neuropathy), if there is a gap bubble, causes it to expand (bowel, pneumothorax, middle ear), Increases ICP
How do you assess the patency of a patients airway?
Look for chest rising and falling
Auscultate both sides for breath sounds
Mask fogging
Monitoring devices
What are common causes of airway obstruction?
Tounge, foreign body
How can upper airway obstruction be relieved?
Jaw thrust
Naso/oropharyngeal airway
Laryngeal mask
ETT
How is an appropriately sized Guedel airway measured?
Approximately the length of the jaw
Compare nasopharyngeal airway to Guedel
Naso is better tolerated and doesn't interfere with loose teeth or dentures, but it may cause bleeding
When would you use a laryngeal mask airway?
When the patient is spontaneously breathing, if cannot place an ETT and can't ventillate
What are the factors to consider when choosing airway management?
ETT is the only definitive airway. Use if pt has reflux, sepsis, in emergency surgery (not fasted), when there is poor access to patient, if there is obstruction
What are the typical ETT sizes for adult males and females?
M: 7.5
F: 7.0
Describe the ideal position for intubation
Flexion of the lower cervical spine and extension of the upper cervical spine
How is the difficulty of intubation graded?
1-4, based on how much of the uvula can be seen when looking into the patient's mouth.
What aids are there for intubation?
Laryngoscope, gum elastic bougie (or stylet in paeds)
How do you confirm an ETT has been placed in the trachea?
Watch chest rise and fall
Auscultate axillae
Look for fogging in the tube
Normal airway pressure cycle
Capnography
Fibre optic scope
What are the consequences of inserting the tube too far?
It may go down one bronchus (R)
How is the airway of a child's (<1yr) different to that of an adult?
Hyperextension of the neck often occludes the airway (so neutral position is often more successful)
Which patients are at risk of aspiration under general anaesthesia?
Non-fasted
Delayed emptying (pyloric obstruction, metabolic (DM), decreased gastric motillity)
Known reflux
Recent trauma
Increased intragastric pressure (intestinal obstruction, pregnancy)
Perioperative opioids
Topically anaesthetised airway
What are the principles of rapid sequence induction?
Indicated when there is a risk of aspiration
Involves preoxygenation, IV induction agent and suxamethonium with cricoid pressure
Describe cricoid pressure and it's use in rapid sequence induction
Cartillage is held between the thumb and middle finger and pressure is exerted with the index finger posteriorly
What drugs are commonly used in rapid sequence induction?
IV induction agent (thiopentone) and suxamethonium
What precautions do you take when performing a rapid sequence induction in someone with a potential cervical spine injury?
Manual inline stabilisation.
One person hold head and crouches to one side. Collar may be flipped open. Cricoid pressure may be omitted if necessary but now it seems that there is no difference between 1 or 2 hands
Describe the use, mechanism of action and adverse effects of midazolam
Induction sedative agent
GABAa agonist at the gamma subunit (increases frequency of channel opening)
May be confused after cessation of prolonged infusion
Describe the use, mechanism of action and adverse effects of propofol
Induction
GAGAa agonist at he beta subunit (increases channel opening time)
May get myoclonic movements, pain on injection, propofol infusion syndrome (cardiac failure, rhabdomyolysis, metabolic acidosis and renal failure and is often fatal)
Describe the use, mechanism of action and adverse effects of thiopentone
Induction.
Barbituate. Positive allosteric modulator at GABAa and glycene receptors, increased chloride channel opening time
Pain
Describe the use, mechanism of action and adverse effects of atropine
Increase heart rate
Muscarinic acetylcholine antagonist (vagal blockade at AV and SA node).
Decreased secretions and lowers oesophageal sphincter tone. Relaxes bronchial smooth muscle. (precent muscarinic side effects with neostigmine)
What is the neurotransmitter at the neuromuscular junction? What receptors are involved?
Acetylcholine
Nicotinic receptors
What is a depolarising muscle relaxant?
Sux is a cholinergic agonist. Not metabolised by acetylcholinesterase so depolarisation of endplate continues for longer inactivating the voltage-gated ion channel- impulses temporarilly cannot pass to motor endplate
What is a non-depolarising muscle relaxant?
Prevents depolarisation but combining reversibly with one or both alpha-subunits, preventing access to ACh to open the ion channel
What are the disadvantages of sux?
Post op muscle pains
Increased intraocular pressure
Increases K+ 0.5
Bradycardias
Malignant hyperthermia
What drugs are given to reverse neuromuscular blockade and how do they work?
Neostigmine
Anticholinesterase inhibitor
What is central venous access and what are potential sites for insertion?
A catheter inserted into a large vein.
Potential sites include: internal jugular, subclavian, femoral, external jugular, basillic/cephallic
What are the indications for central venous cannulation?
Monitor CVP
Certain drugs (adrenaline, noradrenaline, dopamine, TPN)
Failed peripheral access
Sitting neurosurgery (to remove air that has been sucked into venous sinuses)
What are the complications of central venous cannulation?
Infection
Damage to surrounding tissue
Pneumothorax (IJ)
Arrhythmias (if too far down IJ)
Arterial catheterisation
Haemorrhage
WHat is multimodal analgesia?
Combining different classes of analgesia
List adverse effects of pain
CVS: tachycardia, HT, Increased myocardial O2 consumption, venous stasis
Resp: weakened cough, decreased lung volumes, atelectasis, sputum retention
GI: decreased motillity, delayed gastric emptying
GU: urinary retention
Endocrine: stress response hormones released
Psychological
Discuss PCA, it's advantages and disadvantages
Self administration of IV opioids with a push buttin but cannot exceed that maximum toxic conc.
Potentially less opioid used and a sense of control.
Less work for the nurses
Doesn't necessarilly increase patient satisfaction, and sometimes afraid to use because of addiction.
What are the clinical features of opiate overdose? How do you manage a patient with opiate overdose?
Decreased respiratory drive
Pinpoint pupils
Sedation

Manage with naloxone
What factors increase the risk of PONV?
History of PONV
Perioperative opiate use
History of motion sickness
Female
Non-smoker
What is the mechanism of action and the adverse effects associated with the antiemetica metoclopramide and prochlorperazine?
Dopamine antagonist

Dystonia
What is the mechanism of action and the adverse effects associated with the antiemetic odeansetron?
Serotonin receptor antagonist.

Hypotension, headache, flushing
What is the mechanism of action and the adverse effects associated with the antiemetic droperidol?
Dopamine antagonist

Vasodilation, dypotension, dystonia
What is the mechanism of action and the adverse effects associated with the antiemetic dexamethasone?
Steroid

Interacts with (?)cholinesterases to increase weakness in myasthenia gravis
How do local anaesthetics work?
Block conduction of nerve via sodium channel
Why is adrenaline added to local anaesthetic?
Decreases vascular reabsorption
Increases duration of action by making more drug available
Decreases haemorrhage
What is the onset and duration of action of lignocaine, bupivacaine and ropivacaine?
Lignocaine: fast onset, medium acting
Bupivacaine: medium onset, long duration
Ropivacaine: medium onset, long acting
What are the symptoms and signs of local anaesthetic toxicity?
Severe: death, respiratory arrest, arrhythmias, CV collpse
Moderate: altered LOC, convulsions
Mild: perioral tingling, metallic taste, tinnitus, visual disturbance, slurred speech