Clinical Anaesthetics Flashcards
Match each of the following profiles to the correct induction agent:
- Cardio-respiratory depressant, useful in status epilepticus, gives a ‘hangover’ effect, dangerous if given into artery or extravascularly
- Does not depress cardiovascular function and so is preferred in TBI and surgeries where hypotension must be avoided
- Anti-emetic, cardiovascular depressant, risk of bacterial growth in opened ampoules
- May increase cardiac output, bronchodilator, useful in status asthmaticus, causes salivation and prolonged recovery time with risk of distressing delirium and hallucination
A. Propofol
B. Ketamine
C. Etomidate
D. Thiopental
- Cardio-respiratory depressant, useful in status epilepticus, gives a ‘hangover’ effect, dangerous if given into artery or extravascularly - D. Thiopental
- Does not depress cardiovascular function and so is preferred in TBI and surgeries where hypotension must be avoided - C. Etomidate
- Anti-emetic, cardiovascular depressant, risk of bacterial growth in opened ampoules - A. Propofol
- May increase cardiac output, bronchodilator, useful in status asthmaticus, causes salivation and prolonged recovery time with risk of distressing delirium and hallucination - B. Ketamine
Give the appropriate intravenous doses for each induction agent:
A. Propofol
B. Ketamine
C. Etomidate
D. Thiopental
A. Propofol - 1.5-2.5 mg/kg
B. Ketamine - 1-4.5 mg/kg
C. Etomidate - 150-300 mcg/kg
D. Thiopental - 100-150mg
How is ideal bodyweight calculated?
Male = 50kg + 2.3kg for each inch over 5 feet tall.
Female = 45.5kg+2.3kg for each inch over 5 feet tall.
Describe the classes of Mallampati scoring
Class 1: Entire Tonsil clearly visible
Class 2: Upper half of Tonsil fossa visible
Class 3: Soft and Hard Palate clearly visible
Class 4: Only Hard Palate visible
How should you determine what size ET tube to use?
Adult ID: male = 8.5mm, female = 7.5mm
Children ID = [age in years/4] + 4.0mm
Neonate ID = 3–3.5mm
Length (oral) = [age of child/2] + 12.5cm
Length (nasal) = [age of child/2] + 14.5cm
Define “Minimum Alveolar Concentration” value of an anaesthetic
The minimum concentration of an inhalation agent required within the alveoli to stop 50% of patients from moving when exposed to a surgical incision
Which of the following statements is false?
A. Inhalational agents could theoretically be used alone to achieve the triad of anaesthesia
B. Benzodiazepines are used to produce amnesia, but not for analgesia in theatre
C. Most paralysis agents used in surgery are non-depolarising
D. Most intravenous induction agents produce analgesia
E. Opiates potentiate anaesthetic agents, but do not themselves produce adequate unconsciousness in surgery
D. Most intravenous induction agents produce analgesia
The exception is Ketamine, but is important to remember that the others (Propofol, Etomidate, and Thiopentol) produce hypnosis and amnesia but not analgesia. They are also poor at inhibiting reflexive movement in surgery. By contrast, inhalational agents can produce all aspects of anaesthesia if used at high enough doses, though this is not ideal and not done in practice.
What is usually the earliest effect of sedative drugs (i.e. occurs first and at the lowest dose)?
Anxiolysis
How long must a patient be fasted for before an operation?
6 hours for food
2 hours for clear liquid (including black tea and coffee)
Give 5 common complications of an epidural or spinal
Common complications include:
Shivering
Hypotension
Post-dural puncture headache
Inadequate effect
Nausea
Urinary retention
Give 5 rare complications of a neuraxial block
Rare (1 in >5000) complications include:
Meningitis
Respiratory arrest
Cardiovascular collapse
Systemic local anaesthetic toxicity
Spinal/ epidural haematoma
Give the 3 absolute contraindications to a neuraxial block
Patient refusal
Site infection
Significant uncorrected hypovolaemia
Give 5 relative contraindications to a neuraxial block
Coagulopathy/anticoagulant therapy
Aortic/mitral stenosis: there is a risk of profound hypotension from sympathetic blockade
Previous back surgery: there may be a technical difficulty
Systemic sepsis: there is a risk of ‘seeding’ an abscess
Pre-existing neurological disease: there may be medicolegal disputes about ‘new’ symptoms
What is the earliest sign of local anaesthetic toxicity?
Numbness of the tongue and around the mouth, and tinnitus
What is the Hagen-Poiseulle formula?
Q = Pπr^4/ 8nl
Q = flow
P = pressure gradient along tube
r = tube radius
n = fluid viscosity
l = tube length
