EMERGENCY DRUGS Flashcards
Drugs used in cardiac arrest?
Adrenaline IV
Amiodarone IV
Prescription of adrenaline in cardiac arrest?
In cardiac arrest (pre-filled syringe 1:10,000, 1mg in 10mL)
• If shockable, adrenaline 1mg IV given after 3rd shock and repeated every 3-5 minutes
• If not shockable, adrenaline 1mg IV ASAP and repeated every 3-5 minutes
Mechanism of adrenaline in cardiac arrest?
Potent agonist of A1, A2, B1, B2 adrenoreceptors
Fight or flight sympathetic actions:
• Alpha-1 – Vasoconstriction
• Beta-1 - Tachycardia, inotropy, myocardial excitability
• Beta- 2 - Vasodilation of vessels in heart and muscles
• Bronchodilation and suppression of inflammatory mediators from mast cells
Side Effects of adrenaline in cardiac arrest?
Hypertension
Anxiety, tremor, headache, palpitations
Angina, MI and arrhythmias
Contraindications of adrenaline in cardiac arrest?
LA with adrenaline to areas supplied by end-artery (fingers, toes, penis) - tissue necrosis due to vasoconstriction
Dose of amiodarone in cardiac arrest?
In cardiac arrest, given after 3rd shock
• 300mg IV, followed by 20ml of 0.9% NaCl flush
Consider a further 150mg IV after 5 shocks
Mechanism of amiodarone in cardiac arrest?
Block of Na, Ca and K channels
Antagonist of α- and β-adrenergic receptors
Reduce spontaneous depolarisation, slow conduction velocity, and increase resistance to depolarisation, including in the AV node
Side Effects of amiodarone in cardiac arrest?
Hypotension during IV infusion
Chronic – pneumonitis, bradycardia, AV block, photosensitivity, grey discolouration and thyroid abnormalities
Long half-life and takes months to be eliminated
Dose of oxygen in acute pulmonary oedema?
15L/min via non-rebreathe mask if severe
If needed, CPAP, BiPAP and intubation
Mechanism of oxygen in acute pulmonary oedema?
Increase PO2 in alveolar gas, driving more rapid diffusion into blood
Side Effects of oxygen in acute pulmonary oedema?
Discomfort of face mask
Dry mouth
Dose of furosemide in acute pulmonary oedema?
IV 40-80mg furosemide slowly initially
Subsequent boluses, IV infusion or maintenance may be needed
Mechanism of furosemide in acute pulmonary oedema?
Act on ascending limb of loop of Henley
• Inhibit the Na+/K+/2Cl−co-transporter
• Responsible for ions transport from lumen into epithelial cells, water then follows
• Inhibition has diuretic effect
Dilatation of capacitance veins
• Reduce preload and improve contractile function of heart muscle
Side Effects of furosemide in acute pulmonary oedema?
Dehydration and hypotension
Low electrolyte state – Urinary excretion of Na, Cl and K and increase excretion of Mg, Ca and H ions
Hearing loss and tinnitus
Dose of nitrates in acute pulmonary oedema?
Glyceryl trinitrate (2-5mg buccal) if BP>90 systolic
Glyceryl trinitrate IV 50 mg in 50 ml 0.9% sodium chloride at 2 ml/hour, titrating up to 20 ml/hr, maintaining BP > 90 systolic
Mechanism of nitrates in acute pulmonary oedema?
Converted to NO which increases cGMP synthesis and reduced intracellular Ca2+ in vascular smooth muscle cells causing relaxation
Venous and arterial vasodilatation
Relaxation of venous capacitance veins
• Reduce preload and LV filling
• Reduce cardiac work and myocardial oxygen demand
Side effects of nitrates in acute pulmonary oedema?
Flushing, headaches, light-headedness and hypotension
Tolerance with sustained use – nitrate free period overnight to minimise
Contraindications of nitrates in acute pulmonary oedema?
Avoid in phosphodiesterase inhibitors – hypotension
Dose of morphine in acute pulmonary oedema?
Diamorphine 2.5-5mg, at 1mg/minute IV slowly
Morphine 5-10mg (lower in elderly), at 2mg/minute
Mechanism of morphine in acute pulmonary oedema?
Relieves breathlessness alongside oxygen, furosemide and nitrates
• Blunt medullary response to hypoxia and hypercapnia to reduce respiratory drive and breathlessness
Activation of opioid u receptors in CNS to reduce neuronal excitability and pain transmission
Reduce sympathetic nervous system
• Reduce cardiac work and oxygen demand
Side effects of morphine in acute pulmonary oedema?
Respiratory depression Euphoria and detachment Nausea and vomiting Pupillary constriction Constipation • Increased smooth muscle tone and reduced motility Itching, urticaria and sweating
Contraindications of morphine in acute pulmonary oedema?
Dose reduction – hepatic failure, renal impairment and elderly
Avoid in biliary colic – spasm of sphincter of Oddi
Does of oxygen in acute severe asthma?
15L/min via non-rebreathe mask
Maintain oxygen saturations 92-96%
Mechanism of oxygen in acute severe asthma?
15L/min via non-rebreathe mask if severe
If needed, CPAP, BiPAP and intubation
Side effects of oxygen in acute severe asthma?
Discomfort of face mask
Dry mouth
Dose of nebulised salbutamol in acute severe asthma?
5mg every 15-20 minutes if not helping, or back-to-back
Can combine with ipratropium bromide 500mcg
Mechanism of nebulised salbutamol in acute severe asthma?
Stimulation of GPCR leads to smooth muscle relaxation
• Improves airflow in airways
Stimulate Na/K/ATPase pumps on cell surface membranes
• Shift of K into cells
• Useful in hyperkalaemia
Side effects of nebulised salbutamol in acute severe asthma?
Tachycardia, palpitations, anxiety, tremor
Increase glucose levels
Dose of ipratropium in acute severe asthma?
500mcg nebulised every 4-6 hours if needed
Mechanism of ipratropium in acute severe asthma?
Competitively inhibit acetylcholine
• Increase HR and conduction
• Reduce smooth muscle tone
• Reduce secretions
Dose of hydrocortisone in acute severe asthma/COPD?
Asthma
• IV 100mg every 6 hours until conversion to oral prednisolone
• Or oral prednisolone 40mg OD if not too severe
COPD
• IV 200mg
Mechanism of hydrocortisone in acute severe asthma?
Upregulate anti-inflammatory genes and downregulate pro-inflammatory genes
Glucocorticoid effects
• Supress circulating monocytes and eosinophils
• Gluconeogenesis from fatty acids
Mineralocorticoid effects
• Stimulate Na and water retention and K excretion in renal tubule
Dose of aminophylline in acute severe asthma?
Slow IV injection
Child - 5 mg/kg (max. per dose 500 mg)
Adult - 250–500 mg (max. per dose 5 mg/kg)
Followed by IVI
Dose of magnesium sulphate in acute severe asthma?
o Given IV in severe acute asthma
o Sometimes in polymorphic VT
o Adult - 1.2g-2g over 20 minutes
o Child 2-17 – 40mg/kg over 20 minutes (max 2g)
Drugs given in anaphylaxis?
Oxygen Adrenaline IV fluids Chlorphenamine Hydrocortisone
Dose of adrenaline given in anaphylactic shock?
In anaphylaxis (0.5ml of 1:1000, 1mg in 1ml IM into anterolateral thigh)
• Adults or child >12 years - 500mcg IM (0.5ml)
• Child 6-12 years – 300mcg (0.3ml)
• Child <6 years – 150mcg (0.15ml)
Repeat every 5 minutes if needed
Mechanism of adrenaline given in anaphylactic shock?
Potent agonist of A1, A2, B1, B2 adrenoreceptors
Fight or flight sympathetic actions:
• Alpha-1 – Vasoconstriction
• Beta-1 - Tachycardia, inotropy, myocardial excitability
• Beta- 2 - Vasodilation of vessels in heart and muscles
• Bronchodilation and suppression of inflammatory mediators from mast cells
Side effects of adrenaline given in anaphylactic shock?
Hypertension
Anxiety, tremor, headache, palpitations
Angina, MI and arrhythmias
Dose of IV fluids given in anaphylactic shock?
o 500-1000mls IV 0.9% NaCl
Dose of chlorphenamine in anaphylactic shock?
IV slowly/IM • Adult or child > 12 years - 10 mg • Child 6 - 12 years 5 mg • Child 6 months to 6 years 2.5 mg • Child less than 6 months 250 micrograms/kg
Mechanism of chlorphenamine in anaphylactic shock?
Antagonist of H1 receptors
Histamine released from mast cells as a result of binding to IgE on cell surface
H1 increases capillary permeability, oedema (wheal), vasodilation (flare) and itch
Side effects of chlorphenamine in anaphylactic shock?
Sedation
Contraindications of chlorphenamine in anaphylactic shock?
Severe liver disease – precipitate hepatic encephalopathy
Dose of hydrocortisone in anaphylactic shock?
Anaphylaxis (IM or slow IV) • Adult or child > 12 years - 200 mg • Child 6 - 12 years - 100 mg • Child 6 months to 6 years - 50 mg • Child less than 6 months - 25 mg
Mechanism of hydrocortisone in anaphylactic shock?
Upregulate anti-inflammatory genes and downregulate pro-inflammatory genes
Glucocorticoid effects
• Supress circulating monocytes and eosinophils
• Gluconeogenesis from fatty acids
Mineralocorticoid effects
• Stimulate Na and water retention and K excretion in renal tubule
Drug given in benzodiazepine overdose?
- Flumazenil
Dose of flumazenil in benzodiazepine overdose?
Flumazenil IV 200-300ug over 15s, then 100ug at 60s intervals
Needs expert advice before given
Mechanism of flumazenil in benzodiazepine overdose?
Benzodiazepine antagonist
• Reverses CNS depression
Side effects of flumazenil in benzodiazepine overdose?
Risk of provoking seizures
Drugs given in hypoglycaemia?
Glucose
Glucogon
Mild hypoglycaemia treatment?
o 10-20g oral fast-acting carbohydrate (GlucoGel, Lucozade, sugar lumps)
Repeat if necessary
o If fixes then carbohydrate snack
Severe hypoglycaemia treatment?
Glucagon
• 1mg SC/IM (not suitable for alcoholics)
• Given is IV access not available or at home
Glucose
• 10g IV infusion as Glucose 20% in large vein (75-80mls)
• Then oral glucose once patient recovers consciousness
Dose of IV fluids in hypovolaemic shock?
9% saline 500mls over 5-15 minutes
Repeated up to 2L then expert help needed
Drug given in opioid intoxication?
Naloxone IV or IM
Dose of naloxone given in opioid overdose?
IV injection
• Initial 400mcg
• 800mcg for up to 2 doses at 1-minute intervals if no response
• Increased to 2mg for 1 dose if still no response
Can be given SC or IM if IV route not feasible but IV has more rapid onset
Mechanism of naloxone given in opioid overdose?
Competitive antagonist to opioid receptors and reverses the effect of opioids
Side Effects of naloxone given in opioid overdose?
Opioid withdrawal – pain, restlessness, nausea and vomiting, dilated pupils, cold/dry skins
Drugs given in seizures?
Lorazepam/Diazepam/Midazolam
Phenytoin
Dose of lorazepam in seizures?
Given after 5 minutes, 1-2mg Lorazepam IV slow bolus up to 4mg
• Repeat if necessary after 5 minutes
Mechanism of lorazepam in seizures?
GABA is chloride channel and main inhibitory neurotransmitter in brain
Facilitate and enhance binding of GABA to GABAa receptor
• More resistant to depolarisation
Side effects of lorazepam in seizures?
Drowsiness, sedation
Loss of airway reflexes
Dose and route of diazepam in seizures?
0.2-0.5mg/kg (maximum 20mg/dose) rectally as single dose
Or 10mg IV
Dose and route of midazolam in seizures?
Buccal in community
IM 10mg single dose if >40kg, 5mg if <40kg
Dose of phenytoin in seizures?
20mg/kg (maximum 2g/dose) IV as single dose
Maintenance 100mg 6-8 hourly
Mechanism of phenytoin in seizures?
Reduces neuronal excitability and electrical conductance
• Potential Na channels binding, prolonging inactivity
When and what drugs given in hyperkalaemia?
- Immediate treatment if K>6 with ECG changes or K>6.5
- Calcium gluconate or calcium chloride (IV)
- Insulin-glucose solution (IV)
- Salbutamol (nebs)
- Calcium resonium (oral or PR)
Dose of calcium gluconate or calcium chloride in hyperkalaemia?
10% Calcium gluconate 10ml IV via large vein over 5-10mins (up to 30ml)
10% Calcium chloride 10ml over 5-10 mins
Repeat dose after 5-10 minutes if no improvement in ECG
Mechanism of calcium gluconate or calcium chloride in hyperkalaemia?
Raises myocardial threshold potential
• Reduces excitability and risk of arrhythmias
• Protect cardiac membrane
Dose of insulin-glucose solution in hyperkalaemia?
10 units soluble insulin in 50ml 50% glucose over 5-15 minutes
Mechanism of insulin-glucose solution in hyperkalaemia?
Drives K into cells, reducing serum concentrations
• Once stopped, K leaks back out of cells and only short-term measure
Dose of salbutamol nebs in hyperkalaemia?
10-20mg nebulised (5mg back-to-back) over 10-20 minutes
Mechanism of salbutamol nebs in hyperkalaemia?
Stimulate Na/K/ATPase pump causing K shift into cells
Dose of calcium resonium in hyperkalaemia?
15g oral every 6-8 hours with lactulose
30g BDS PR
Mechanism of calcium resonium in hyperkalaemia?
Remove K from body by exchanging for Ca in resin
Slow method