EMT DRUGS REVISED Flashcards
adrenaline mechanism
- Adrenaline stimulates alpha and beta receptors, with the predominant effects occurring at alpha 1, beta 1 and beta 2 receptors.
- Alpha 1 stimulation causes smooth muscle contraction, vasoconstriction of blood vessels and stimulation of glycogenolysis and gluconeogenesis.
- Beta 1 stimulation causes an increase in inotropy (cardiac contractility), an increase in chronotropy (heart rate) and an increase in dromotropy (speed of electrical conduction within the heart).
- Beta 2 stimulation causes smooth muscle relaxation, skeletal muscle vasodilation, bronchodilation, and stabilisation of mast cell membranes, reducing histamine release.
adrenaline indication
EMT
Clinically significant epistaxis
Stridor causing moderate to severe respiratory distress
Anaphylaxis
Severe asthma
Clinically significant bleeding from a wound
Other indications
Cardiac arrest
Imminent respiratory arrest from COPD
Severe bradycardia
BP support if unresponsive to metaraminol
Septic shock, cardiogenic shock, and neurogenic shock, unresponsive to 0.9% sodium chloride IV and metaraminol IV
adrenaline contraindications
nil
adrenaline cautions
Myocardial ischaemia. Adrenaline will increase myocardial oxygen consumption.
Tachydysrhythmias. Adrenaline will usually make tachydysrhythmias wors
topical use of adrenaline
Topical: dilute each mg of adrenaline to a total of 10 ml using 0.9% sodium chloride. This solution is 1:10,000 and contains 0.1 mg/ml. Apply topically in addition to direct pressure.
IN admin of adrenaline
IN for epistaxis
drawup with 8mls sodium chloride
0.2 mg (2 mls) aged 12 and over
0.1 mg (1 mls) 5-11 years.
Repeat dose after 20 mins
IM adrenaline admin
IM for asthma/anaphylaxis
Undiluted
0.5 mg
repeat every 5 to 10 mins
Arrest adrenaline admin
Cardiac arrest: 1mg every 4 mins
a) Adults and children whose weight has been rounded to 50 kg or more: administer undiluted as an IV bolus.
b) Children whose weight has been rounded to 40 kg or less: dilute 1 mg of adrenaline to a total of 10 ml using 0.9% sodium chloride. This solution is 1:10,000 and contains 0.1 mg/ml. Draw up the dose from this solution and administer as an IV bolus.
common adverse affects of adrenaline
- Tachycardia.
- Tachydysrhythmia.
- Myocardial ischaemia.
- Ventricular ectopy.
- Hypertension.
- Nausea and vomiting.
- Tremor, anxiety and sweating.
- Hyperglycaemia.
usual onset of adrenaline
- IV: 5-10 seconds.
- IM: 2-5 minutes.
- Nebulised, IN and topical: on contact with the target site.
duration of adrenaline
- The cardiovascular effects last 5-15 minutes.
- The mast cell membrane effects may last for several hours.
pharmokinetics of adrenaline
- Adrenaline is metabolised by the liver and taken up by sympathetic nerve endings.
- There are no significant effects from liver impairment on acute administration.
common interactions with adrenaline
Increased doses may be required if the patient is taking a beta-blocker or a calcium channel blocker. This effect is particularly prominent in the setting of poisoning if a large dose of a beta-blocker and/or calcium channel blocker has been taken.
aspirin mechnism
Aspirin (acetylsalicylic acid) has antiplatelet, antipyretic, anti-inflammatory and analgesic effects. In the out-of-hospital setting aspirin is only administered for its antiplatelet activity.
* Aspirin inhibits the enzyme cyclooxygenase which results in a reduction in the formation of prostaglandins and thromboxane.
indication of aspirin
myocardial ischemia
contraindications of aspirin
Known severe allergy.
pregnancy
cautions of aspirin
^ Known bleeding disorder. Aspirin will increase the risk of bleeding, however the balance of risk is usually in favour of administering aspirin.
^ Clinically significant bleeding. Aspirin will increase the risk of bleeding and the nature and risk of the bleeding must be taken into account.
^ Known worsening of bronchospasm with NSAIDs. Some patients with asthma or COPD have known worsening of bronchospasm with NSAIDs (including aspirin) and a decision must be made based on the balance of risk. If there
is a clear history of significant bronchospasm with NSAIDs, aspirin should be withheld.
aspirin and pregnancy interactions
- May cause harm during pregnancy. Aspirin has been associated with premature delivery and premature closure of the ductus arteriosus, when administered in the third trimester of pregnancy.
- The likelihood of clinically important myocardial ischaemia occurring in a woman who is pregnant is so low that the balance of risk is usually in favour of aspirin being withheld.
- May be administered if the patient is breastfeeding. Advise the patient to stop breastfeeding and seek further advice from their lead maternity carer or GP
aspirin dosage
300mg
common adverse affects of aspirin
- Increased bleeding.
- Although indigestion, gastrointestinal ulceration and gastrointestinal bleeding are commonly listed as adverse effects, these are only associated with long- term administration.
usual onset of aspirin
- 30-60 minutes.
usual duration of aspirin
- 3-5 days for the antiplatelet activity. This is because platelets exposed to aspirin are impaired for the life of the platelet which is 7-10 days. Approximately 10% of platelets are replaced each day.
pharmokinetics of aspirin
- Absorption occurs in the stomach and small intestine. The presence of food in the stomach will delay absorption, but this is not usually clinically significant.
- Aspirin is predominantly metabolised in the liver.
- There are no significant effects from liver impairment on acute administration.
common interactions of aspirin
- Aspirin displaces warfarin from binding sites and increases the activity of warfarin. However, this effect is most prominent with chronic administration and aspirin is indicated if a patient taking warfarin has clinically significant myocardial ischaemia.