Anaesthetics Flashcards
anaesthetics are either delivered…
IV or inhalational
what anaesthetics are the fastest in inducing anaesthesia?
propofol and etomidate ~ 30 secs
what is unique about propofol as an induction anaesthetic?
Of the available induction agents, propofol has a unique ability to suppress airway reflexes and to produce apnea
How might we clarify correct airway placement of the endotracheal tube?
- Effective manual ventilation.
●Symmetrical chest rise.
●Visible condensation in mask or tube of airway device.
●End-tidal CO2 waveform on gas analyzer.
●If endotracheal tube placed, right mainstem bronchus intubation and esophageal intubation must be ruled out with bilateral breath sounds and lack of sounds of air entry into stomach, and CO2 wave form detection. Especially in thin patients, air entry into the stomach may be heard in the chest and mistaken for breath sounds.
●If a SGA is used, air leak should occur at high enough peak pressure to allow adequate tidal volume, 18 to 20 cm H2O.
another name for suxamethonium?
succinylcholine
3 stages of anaesthesia
- Induction
- Maintenance
- Reversal
what are the 2 forms of GA?
- Spontaneous ventilation (Laryngeal mask airway- supraglottis airway)
- Assisted ventilation with NM blocking agent (endotracheal tube)
what are the 3 types of anaesthesia?
- General Anaesthesia
- Regional anaesthesia
- Local anaesthesia
what are 2 forms of regional anaesthesia?
Epidural
Spinal
when would we consider Assisted ventilation with NM blocking agent and ETT for GA?
Would use assisted ventilation for Neurosurgery, Major cavity surgery, Long surgery and for special anaesthetic indications such as: • Non fasting- trauma • GORD • Pregnancy > 20 weeks • Obesity • OSA etc
complications of anaesthesia?
• Allergy/anaphylaxis • Malignant hypertension • Risk of respiratory depression • Aspiration risk • Damage to spinal nerve (regional) • BLEEDING • INFECTION \+ PONV
where is a spinal anaesthesia injected?
Injected into the Subarachnoid space below L1-L2
what drugs can we use for induction of anaesthesia with spontaneous ventilation?
IV Midazolam
IV Fentanyl
IV Propofol ( the main one)
Or Etomidate
what neuromuscular blocking drugs are there?
Recuronium
/Veccuronium
/atrecurium
describe the procedure of induction of anaesthesia?
- Place oxygen mask on patient
- Ask the patient to take nice deep breaths to fill lungs with oxygen. = PRE-OXYGENATION
- If spontaneous ventilation- laryngeal mask airway- insert and inflate. Attach mask to it.
OR - NM blockers= AcH R competitive antagonists. Non depolarising. If used, must ventilate the patient with endotracheal tube!!
- Intubate with laryngoscope and inflate ETT. Attach mask to it
- Listen to the left hand side bc most likely go down R main bronchus.
- Check CO2 levels
what inhaled drug do we use during maintenance of anaesthesia?
sevoflurane
what other adjunct drugs do we use during maintenance of anaesthesia?
oxygen
morphine IV
what do we do when we reverse anaesthesia?
- Turn off all anaesthetics running
- Turn the oxygen up to 100%
- Maintain analgesia
- If used NM block need neostigmine, which is acetylcholinesterase inhibitor. + atropine (antimuscarinic)
- SLUD effects and bradycardia
Extubate- deflate endotracheal tube
Tell me about ketamine
Dissociative anaesthetic drug
Commony used in developing countries
Causes hypersalivation
Doesn’t ablate reflexes so hard to intubate
what drugs do we use to reverse NM blocking drugs?
Neostigmine
Atropine
Glycopyrolate
Sugammadex
what drugs in particular do sugammadex reverse?
rocuronium and vercuronium
define MAC for inhaled anaesthetics
Each agent has a specific minimum alveolar concentration (MAC), defined as the amount of vapour (%) needed to render 50% of spontaneously breathing patients unresponsive to a standard painful surgical stimulus. MAC is inversely proportional to potency.
Why dont we use desflurane for induction anaesthesia?
causes respiratory and salivary secretions
what type of allergy do we need to worry about with propofol anaesthetic?
egg allergy as propofol emulsion contains egg
is thiopental suitable for maintenance anaesthesia?
no. it has zero order kinetics and rather slow metabolism
what kind of drug is thiopental?
thiobarbituate anaesthetic drug
adverse effects and contraindications for thiopental?
hangover effect, histamine release–> inflammation and contraindicated in porphyria
what are the two groups of local anaesthetics?
amine and esters
which form of local anaesthetic- charged or uncharged, can pass the cell membrane?
uncharged
what is the molecular target for action of local anaesthetics?
blocks sodium channels
tell me about suxamethonium?
suxamethonium is a depolarising neuromuscular blocking drug, that binds to AcH receptors on post synaptic membrane and prevents AcH from binding. Is metabolised by cholinesterase. Very fast acting.
SE of suxamethonium?
Malignant hyperthermia apnea anaphylaxis hyperkalemia increased intraocular pressure myalgia bradycardia histamine release
how do non depolarising neuromuscular blockers work?
they reversibly competitively antagonise Ach receptor
what are the two types of non depolarising neuromuscular blockers?
aminosteroids and benzylisoquinoliniums
where does neostigmine act?
acts on both muscarinic and nicotinic receptors hence SLUD effects
what is neostigmine always administered with?
atropine or glycopyrolate to reduce SLUD effects
how do we assess neuromuscular activity during general anaesthesia using muscle relaxant?
apply charge to ulnar nerve and look for T1 movement. TOF
what kind of drug is metaraminol? why is it used in anaesthetics
metaraminol is an alpha 1 agonist that mediates peripheral vasoconstriction. used for hypotension
