Anaesthesia and Asthma Flashcards

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1
Q

Which volatile gas is a good anaesthetic for kids?

A

Xe

-most of the volatile gases are fluoronated hydrocarbons

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2
Q

Which anaesthetics are given intravenously?

A
  • propofol
  • barbiturates
  • etomidate
  • ketamine
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3
Q

What are Guedel’s signs?

A

Stage 1: analgesia and consciousness
Stage 2: unconscious, breathing erratic but delirium could occur, leading to an excitement phase
Stage 3: surgical anaesthesia, with 4 levels describing increasing depth until breathin weak
stage 4: if no intubation and ventilation then respiratory paralysis and death

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4
Q

What is anaesthesia a combo of?

A
  • analgesia
  • hypnosis
  • depression
  • muscle relaxation
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5
Q

What factors increase or decrease MAC (minimum alveolar concentration)

A
Increase
-age: high in infants
-hyperthermia
-pregnancy
-alcoholism
-central stimulants
Decrease
-age: low in elderly
-hypothermia
-other anaesthetics and sedatives
-opioids (MAC sparing)
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6
Q

What are the effects of nitrous oxide on MAC?

A
  • has analgesic and MAC sparing effect
  • helps to decrease the amount of anaesthesia put in
  • added to other volatile agents to reduce dosing
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7
Q

What is the main intravenous anaesthetic?

A
  • propofol ad barbiturate (rapid)
  • ketamine (slower) (mainly in kids)
  • TIVA: Total IntraVenous Anaesthesia
  • all potentiate GABAa except Ketamine
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8
Q

Give examples of local anaesthetics and their characteristics?

A

-examples: lidocaine, bupivacaine, ropivcaine, procaine
Characteristics
-lipid solubility: potency (higher greater potency)
-dissociation constant (pKa) time of onset, lower pKa fast onset
-chemical link: metabolism
-protein binding: duration (higher for longer duration)

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9
Q

Inhaled corticosteroids (ICS) (beclometasone, budesonide, fluticasone)

A
  • regular preventer when reliever alone not sufficient
  • passes through plasma membrane, activate cytoplasmic receptors, activated receptor then passes into nucleus to modify transcription
  • anti inflammatory, bronchodilator and reduction in mucus
  • reduces symptoms, exacerbations and prevent death
  • can cause a local immunosuppressive action: candidiasis, hoarse voice
  • pneumonia risk possible in COPD
  • if taken correctly very few significant ADRs
  • poor oral bioavailability but high affinity for glucocorticoid receptor
  • lipophilic side chain added so slow dissolution in aqueous bronchial fluid
  • if steroids is absorbed orally then its transported from stomach to liver by hepatic portal system, then goes through almost complete first pass metabolism
  • high doses of ICS can produce systemic side effects
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10
Q

How do steroids work?

A

Gene activation

  • increases B2 receptors
  • anti-inflammatory mediators

Gene repression
-inflammatory mediators: interleukins, chemokines, cytokines

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11
Q

B2 agonists

A
  • SABA: symptom relief through reversal of bronchoconstriction, only to be used prn (as required)
  • LABA: add on therapy to ICS and prn SABA
  • major action on airway smooth muscle and also increases mucus clearance by action of cilia
  • prevention of bronchoconstriction prior to exercise (SABA/LABA)
  • can be used in athletes and asthmatic patients
  • when used regularly can it reduce asthma control-tolerance? A: quick fix, especially in young adults
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12
Q

What are the adverse effects and interactions of B2 agonist?

A
  • adrenergic: fight or flight effects, tachycardia, palpitations, anxiety and tremor
  • Supraventricular tachycardia.
  • increase in glycogenolysis in liver and increase in renin in kidney
  • muscle cramps (LABA)
  • LABA should only be prescribed alongside ICS
  • increased risk of death when prescribed alone
  • B blockers may reduce effects of B2 agonists
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13
Q

Montelukast

A
  • leukotriene receptor antagonist (LTRA) p.o.
  • alternative to LABA in NICE guideline
  • LTC4 released by mast cells/eosinophils —> increase in bronchoconstriction, mucus, oedema through CysLT1 —> GPCR
  • LTRA block CysLT1 (so signalling cascade is blocked which inhibits mucus and oedema)
  • useful in about 15% asthmatics most end up taking LABA
  • ADRs: headache, GI disturbance, dry mouth, hyperactivity
  • no major drug interactions reported
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14
Q

Tiotropium

A
  • long acting muscarinic antagonist (LAMA)
  • severe asthma and COPD
  • relative selectivity for M3 (SAMA much less selective)
  • anticholinergic effects through inhibition of muscarinic receptors
  • ADRs: typical anticholinergic effects, dry mouth, urinary retention, dry eyes
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15
Q

Theophylline

A
  • theophylline a methylxanthine p.o.
  • adenosine receptor antagonist
  • aminophylline soluble form: I in some acute asthma patients)
  • narrow therapeutic index because oral drug
  • potentially life-threatening complications including arrhythmia
  • interaction with CYP450 inhibitors: increase concentrations of theophylline
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16
Q

Prednisolone

A
  • oral steroids
  • severe uncontrolled asthma: specialist direction, steroid card
  • post acute exacerbation: at least 5 days
  • post acute COPD: 5 to 7 days
17
Q

Ipratropium

A
  • nebulised ipratropium bromide: short acting muscarinic antagonist (SAMA) alongside B2 agonist if poor response alone
  • less selective for M3 receptors compared to tiotropium
  • consider IV aminophylline if life threatening and no success with above (caution if taking p.o. Theophylline)
18
Q

What would you prescribe for COPD?

A
  • in acute exacerbation: give hospitalisation
  • nebulised salbutamol and/or ipratropium should be prescribed if patient is hypercapnic or acidotic nebuliser should be driven by air and not oxygen
  • oral steroids: can be less effective than in eosinophilia asthma due to reduced action on neutrophils
  • antibiotics (narrow spectrum: less severe, broad spectrum: greater severity)
  • review of chronic treatment and action plan
19
Q

What inhalers are there?

A
  • pressurized metered dose inhalers (pMDI)., inhalation and actuation of device, slow breath in and hold, can be used with a spacer to improve delivery
  • contained CFC, bad for environment, useful in kids
  • breath-actuated pMDI
  • automated actuation: upon inspiration
  • improves the coordination issues such as for cognitive impaired patients
  • dry powder inhalers (DPI)
  • micro ionized drug plus carrier powder
  • own inspiratory flow: fast deep inhalation