Zero to Finals : General anaesthesia Flashcards by Rassa Kapite

What are the 2 main categories of anaesthesia?

General
Regional

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Define general anaesthesia

Making the patient unconcious

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Define Regional anaesthesia

Blocking feeling to an isolated area of the body

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What type of respiratory support is in place during general anesthesia for an operation?

Intubation / Supraglottic airway device
breathing suppoerted by ventilator

Patient is continuously monitored at all times immediately before, during and after general anaesthesia

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Prior to general anaesthesia, what type of preperation must be done?

If possible:
* Fasting (reduce risk of reflux and spiration)

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What are the possible consequences of a patient not fasting prior to undergoing general anaesthesia?

Preperation

Aspiration of gastric contents into airway -> inflammitory response (pneumonitis)

Highest risk before and during intubation and during extubation

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What are the 2 major causes of morbidity and mortality in general anaesthetics?

Preperation

Apiration pneumonitis
Pneumonia

Although rare in non-emergency planned procedures

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How long is the fasting period typically?

Preperation

6hrs (no food/feeds) prior to op
2 hrs of no clear fluids (NBM)

NBM: nil by mouth

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Why is it important to preoxygenate the patinet prior to undergoing general anaesthesia?

Preperation

To provide a reserve of oxygen for the period between when they lose consciousness and are successfully intubated and ventilated (in case the anaesthetist has difficulty establishing the airway)

Patinet breathes 100& O2 for several mins prior to going under

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What medications may be given to a patient prior to the undergoing general anaesthesia?

Preperation

Benzodiazepines (e.g. midazolam): muscle relaxant/reduce anxiety, causes amnesia
Opiates (e.g. fentayl/alfentanyl): pain management/reducehypertensive response to laryngoscope
Alpha-2-adregenic agonist (e.g. clonidine): sedation/pain

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When is RSI performed?

What is RSI?

RSI= Rapid Sequance Induction/Intubation

Gain control over the airway (quickly/safely) in emergency situations
Non-emergency situations where the airway needs to be secured quickly to avoid aspiration (e.g. GORD/Pregnancy )

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How may the risks associated with performing RSI be minimised?

Risk: Aspiration of stomach contents
Minimised by:
* Bed positioned upright
* Cricoid pressure (compress oesophagus/prevent reflux- ONLY used by trained/experinced health professionals)

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Whta is the triad of General Anaesthesia?

Hypnosis
Muscle relaxation
Analgesia

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What 2 modes may hypnosis be induced in patients?

Hyponsis

IV
Inhalational

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List some hypnotic IV agents used in GA?

Propofol (the most commonly used)
Ketamine
Thiopental sodium (less common)
Etomidate (rarely used)

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What are some adverse effects of propofol?

Pain on injection (due to activation of the pain receptor TRPA1)
Hypotension

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What is an adverse effectof thiopental?

Laryngospasm

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What are some adverse effects of etomidate?

Primary adrenal suppression (secondary to reversibly inhibiting 11β-hydroxylase)
Myoclonus

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In cases of hameodynamic instability, what IV hypnotic agent is used and why?

Etomidate
Causes less hypotension than propofol and thiopental during induction

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What are some adverse effects of Ketamine?

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Disorientation
Hallucinations

What IV hyponitic agent is useful in trauma situations and why?

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Ketamine
Doesn’t cause a drop in blood pressure

What is the most commonly used IV Hypnosis agent in GA?

Hyponosis

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Propofol

Used extensively in intensive care for ventilated patients

List some Inhalational hypnotic agents used in GA?

Hypnosis

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Volatile Liquid anaetshtics:
* Sevoflurane (the most commonly used)
* Desflurane (less favourable as bad for the environment)
* Isoflurane (very rarely used)

Other:
* Nitrous oxide (combined with other anaesthetic medications – may be used for gas induction in children)

What are some adverse effects of volatile liquid anaesthetics?

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e.g. isoflurane, desflurane, sevoflurane

Myocardial depression
Malignant hyperthermia
Halothane (not commonly used now) is hepatotoxic

Used for both induction and maintenance of GA

What is the most commonly used inhalational hypnotic agent in GA? | Hypnosis

Sevoflurane

What inhalational hypnotic agent is used in GA in children?

**Nitrous oxide** (combined with other anaesthetic medications – may be used for gas induction in children)

Waht conditions that patients may have CI use fo NO for general anaesthesia?

Pneumothorax May diffuse into gas-filled body compartments → increase in pressure ## Footnote Used for maintenance of anaesthesia and analgesia (e.g. during labour)

What devices are used for inhaled volatile agents? How do these work? | Hypnosis

Vaporiser: * The liquid medication is poured into the machine. * The machine then turns it into vapour and mixes it with air in a controlled way. * During the anaesthesia, the concentration of the vaporised anaesthetic medication can be altered to control the depth of anaesthesia.

a) What mode of administartion is most commonly used for induction of GA? b)What mode of administartion is most commonly used for maintenance of GA? Why is this? | Induction

a) **IV**: infused directly into the blood and so can quickly reach an effective concentration b) **Inhalational**: need to diffuse across the lung tissue and into the blood, where it takes a while for them to reach an effective concentration. Convcentration can be controlled easier

What is TIVA?

**Total intravenous anaesthesia (TIVA)**: * involves using an intravenous medication for induction and maintenance of GA Propofol is the most commonly used. This can give a nicer recovery (as they wake up) compared with inhaled options.

How do muscle relaxants work? | Muscle relaxants

**Block the neuromuscular junction from working** Acetylcholine (the neurotransmitter) is released by the axon but is blocked from stimulating a response from the muscle (msucle is relaxed/paralysed)

What are the 2 categories of muscle relaxants used in GA? | Muscle relaxation

* **Depolarising** (e.g., suxamethonium) * **Non-depolarising** (e.g., rocuronium and atracurium)

What medications can reverse effects of neuromuscular junction blocking medications? | Muscle relaxants

**Cholinesterase inhibitors** (*e.g., neostigmine*) Sugammadex is used specifically to reverse the effects of certain non-depolarising muscle relaxants (rocuronium and vecuronium).

What medication category is most frequently used for analgesia? | Analgesia

Opiates

List some common analgesic agents used in GA? | Analgesia

* Fentanyl * Alfentanil * Remifentanil * Morphine

What medications are administered at the end of the ooperative procedure? What are most common types given to patients?

**Antiemeteics**: prevent post-operative nausea and vomiting * **Ondansetron** (5HT3 receptor antagonist) – avoided in patients at risk of prolonged QT interval * **Dexamethasone** (corticosteroid) – used with caution in diabetic or immunocompromised patients * **Cyclizine** (histamine (H1) receptor antagonist) – caution with heart failure and elderly patients

What antiemetic medication should be avoided in pts with risk of prolonged QT interval?

Ondansetron (5HT3 receptor antagonist)

What antiemetic medication should be used with caution in diabetic or immunocompromised patients?

Dexamethasone (corticosteroid)

What antiemetic medication should be used with caution in heart failure and elderly patients?

Cyclizine (histamine (H1) receptor antagonist)

What must be done prior to emergence from GA?

* **Reversal of muscle relaxants** (prevent awareness under anaesthesia)- can be tested with nerve stimulators to ensure muscle relaxant effects have ended (done on ulnar n./facial n using TOF stimualtion) ## Footnote TOF Stimulation : Train of four stimulation (nerve stimualted 4 times to check for appropriate response

What does the anaesthetist control during the emergence phase of GA?

* Switches off anaesthetics (concentration of anaesthetic in the body falls, the patient regains concioussness) * Extubation

What are the most common side effecst of GA?

* Sore throat * Post-op nausea/vomiting

What are some significant risks of general anaesthesia?

* Accidental awareness (waking during the anaesthetic) * Aspiration * Dental injury, mainly when the laryngoscope is used for intubation * Anaphylaxis * Cardiovascular events (e.g., myocardial infarction, stroke and arrhythmias) * Malignant hyperthermia (rare) * Death

What agents increase risk of malignant hypothermia during GA?

* Volatile anaesthetics (isoflurane, sevoflurane and desflurane) * Suxamethonium

What increases risk of malignant hyperthermia?

Genetic mutation (autosomal dominant)

What does malignant hyperthermia cause?

* Increased body temperature (hyperthermia) * Increased carbon dioxide production * Tachycardia * Muscle rigidity * Acidosis * Hyperkalaemia

How is malignant hyperthermia treated?

**Dantrolene** (interrupts the muscle rigidity and hypermetabolism by interfering with the movement of calcium ions in skeletal muscle)

Waht conditions that patients may have CI use fo NO for general anaesthesia?

Pneumothorax May diffuse into gas-filled body compartments → increase in pressure ## Footnote Used for maintenance of anaesthesia and analgesia (e.g. during labour)

Zero to Finals : General anaesthesia Flashcards

(48 cards)