Section 1 knowledge bites Flashcards
Drugs to stop in haemoptysis?
Antiplatelets - aspirin
LMWH - enoxaparin
Drug to stop if hyperkalaemia
ACEi
Fluid containing potassium (alternative started)
What is the PReSCRIBER mnemonic
A mnemonic to remember the essentials to do for every patient when you prescribe a drug:
- Patient details (don’t prescribe if pts name doesn’t match the prescription)
- REaction (note any allergies)
- Sign (the front of the chart)
- Contraindications (check for each drug you prescribe)
- Route (check for each drug)
- IV fluids (check if needed and check things added, e.g., K+)
- Blood clot prophylaxis (prescribe if needed or remove if CI e.g. active bleeding)
- antiEmetic (prescribe if needed)
- pain Relief (prescribe if needed)
4 groups of CI to know - 1:
Drugs that increase bleeding (e.g. antiplatelets and anticoagulants) should not be given to (2)…
- Pts who are bleeding/suspected of bleeding
- At risk of bleeding (e.g. prolonged prothrombin time due to liver disease).
NB prophylactic heparin is generally not appropriate in acute ischaemic stroke due to risk of bleeding into the stroke.
Also NB enzyme inhibitors (e.g. erythromycin) can increase warfarin’s effect (increase PT/INR) despite a stable dose. Consider in pts with excessive anticoagulation.
4 groups of CI to know - 2:
Remember the SE of steroids (and thus, more loosely, the CI). Hint - mnemonic STEROIDS
- Stomach ulcers (co-prescribe PPI)
- Thin skin
- oEdema
- Right and left HF
- Osteoporosis
- Infection (esp. candida)
- Diabetes (commonly causes hyperglycaemia and uncommonly progresses to diabetes)
- cushing’s Syndrome
4 groups of CI to know - 3:
The following safety considerations of NSAIDs. Hint NSAID mnemonic
What about aspirin?
- No urine (i.e. renal failure)
- Systolic dysfunction (.e. heart failure)
- Asthma
- Indigestion (any cause, esp. ulcers)
- Dyscrasia (clotting abnormality)
While aspirin technically an NSAID, generally used a low doses for Mx of CVD and CVA, which for such use, it is not necessarily subject to the same level of caution as NSAIDs for pain Mx.
4 groups of CI to know - 4:
The 3 groups of SE/CI for antihypertensives:
- Hypotension (including the earliest symptom - postural hypotension). May result from all groups of anti-HTN.
- Dividing groups of antihypertensives into 2 mechanistic categories:
- Bradycardia - may occur with BB and some CCBs.
- Electrolyte disturbance with ACEi and diuretics
- Individual drug classes have specific SE:
- ACEi can cause dry cough
- BB can cause wheeze in asthmatics (can also worsen acute HF but help chronic HF).
- CCBs can cause peripheral oedema and flushing
- Diuretics can cause renal failure. Thiazide diuretics can cause gout, and potassium sparing diuretics can cause gynaecomastia.
What things to consider regarding route of a drug?
Vomiting - antiemetics given non-oral (however, if vomiting predicted to last a short time which it usually is, not usually necessary to change route of other prescribed drugs).
Conveniently, doses of common antiemetics are the same regardless of the route taken, e.g. cyclizine 50mg 8-hrly, metoclopramide 10mg 8-hrly.
If a pt is NBM, should still receive their oral medication, including prior to surgery.
What are the two instances fluids are prescribed?
- As replacement for dehydrated/acutely unwell pts
- As maintenance for pt NBM
Regarding replacement fluids:
- Which fluid?
Generally, 0.9% saline or Hartmann’s, unless pt is:
- Hypernatraemia or hypoglycaemic - give 5% dextrose instead.
- Has ascites - give Human-albumin solution
- Is shocked from bleeding - give blood transfusion, but crystalloid first if no blood available.
Regarding replacement fluids:
- how much and how fast?
Assess HR, BP and urine output:
- If tachycardiac or hypotensive, give 500mL bolus immediately (250ml if Hx of HF) then reasses (HR, BP, urine output) to assess response and speed of next back.
- If only oliguric (and not due to urinary obstruction) give 1L over 2-4hrs then reassess pt.
As a general rule, never prescribe >2L IV fluid for a sick patient. May add K+ but no more than 10mmol/hr.
How can you estimate how fluid deplete a pt is?
Can use their observations and knowing which are affected first:
- Reduced urine output (oliguric if <30mL/h) indicates 500mL of fluid depletion.
- Reduced urine output + tachycardia indicates 1L of fluid depletion
- Reduced urine output + tachycardia + shocked indicates >2L fluid deplete
Regarding maintenance fluids:
- Which fluids?
- how much?
As a general rule, adults require 3L IV fluid/24hrs and elderly 2L.
Adequate electrolytes are provided by 1L of 0.9% saline and 2L 5% dextrose (1 salty, 2 sweet).
To give potassium, bags of 5% dextrose or 0.9% saline containing KCl can be used but U&E should guide this. With normal K level, pts require roughly 40mmol KCl/day (so put 20mmol KCl in 2 bags)
Regarding maintenance fluids:
- How fast?
If giving 3L/day - 8-hourly bags (24/3)
If giving 2L/day - 12-hourly bags (24/2)
Then reassess pt (U&Es, signs of overload, ensure bladder not palpable signifying obstruction and fluids given due to reduced urine output).
Who requires VTE prophylaxis and who doesnt?
Most require LMWH (e.g. deltaparin 5000units daily s/c) and compression stockings for prevention of VTE.
Do not learn criteria of who does/doesnt.
If pt is bleeding or at risk (including recent ischaemic stroke) they should not be prescribed anticoagulants.
A pt with peripheral artery disease (absent foot pulses) should not be prescribed compression stockings as may cause acute limb ischaemia.
