For as long as I can remember the mantra for chest pain management was MONA. Standing for Morphine, Oxygen, Nitrates and Aspirin, MONA has largely gone unchallenged for 25 years. The exception is the deemphasis on using Oxygen, and a 2011 report challenging the use of morphine in Acute cardiac failure but that is a whole other post.
In this episode of #KnowingYourJargon (KYJ) we explore the rationale for Aspirin.
Aspirin or Acetyl Salicylic Acid (ASA) is an ancient non-steroidal anti inflammatory drug (NSAID) used originally as a tooth ache remedy when the bark of the Willow tree was chewed by tribesmen and women.
It has so many great uses, but is not with out its problems. It can initiate asthma flare ups, so caution in these patients is needed. Gastritis and epigastric pain is a common concern, especially if taken on an empty stomach. In the 60s and 70s parents giving aspirin to febrile children discovers that some children developed a rash, vomiting, liver and brain damage, and died. The collection of symptoms was termed Reyes Syndrome, and for this reason, aspirin is not recommended for children under 13. At around the same time aspirin powders marketed under the trade names Bex and Vincent's powder, were a housewife favourite that resulted in a spike in kidney failure in much the same way that we are seeing a current increase in incidence of kidney disease from ibuprofen and other NSAID over use, but I digress.
Aspirin exerts an anti-platelet function. Platelets secrete a surface protein which is a prostaglandin chemical that signals other platelets to clump together, and form a clot.
Aspirin (like other non-steriodal antiinflammatories) acts by inhibiting these prostaglandins from forming. It permanently disables the platelet, rendering it useless for the rest of it's life (7-10days).
In chest pain of cardiac cause, the ischaemia is usually due two mechanisms; vessel spasm, and clot formation. Enter the use of Aspirin. If we give aspirin, we disable the platelet, resulting in inhibited clot formation.
150-300mg chewed or dissolved and given orally is indicated for chest pain patients as soon as possible. It should be stated that this is standard chest pain protocol, but only if not contraindicated. Active bleeding, allergies, and hypersensitivity would all be reasons not to administer aspirin as a routine.
Because aspirin inhibits prostaglandin production, it also inhibits protective prostaglandins like those that protect the stomach from erosive gastric juices. This is the link between gastritis and aspirin.
Aspirin is a versatile drug, and in chest pain, is a life saving intervention with its anti platelet effect. More and more , it is used with an adjunct drug called Clopidogrel. This also works on the platelets surface inhibiting their ability to stick to each other causing a clot. This process is called platelet activation, and together aspirin and clopidogrel are a great team in inhibiting the thrombus formation and snowballing.
"Rusty Pills" our newest Pharmacology refresher seminar is coming soon. Check out our upcoming courses including Rusty Pills here
No comments:
Post a Comment