Periop Drugs Flashcards
What are the risk factors for NSAID ulceration?
- over 60yrs
- previous peptic ulceration
- type of NSAID (ibuprofen is safest)
- dose of NSAID
- concomitant steroid usage (note: only concomitant, steroids do not increase risk on their own)
- concomitant anticoagulant usage
Give some examples of abdominal bleeding caused by warfarin usage.
- rectus sheath haematoma (severe pain; use of rectus muscles increases pain)
- intraperitoneal bleeding
- retroperitoneal haematoma (small tears in retroperitoneum; similar presentation to AAA)
Give some examples of surgical complications of OCP use.
- DVT/PE (5% of UK women have activated protein C resistance/Factor V Leiden defect)
- mesenteric venous thrombosis
- ischaemic colitis
- hepatic adenomas
- ectopic pregnancy (POP not COCP)
Give some examples of drug classes causing diarrhoea.
- beta-blockers
- misoprostol (abortifacent/labour induction/post-partum bleeding/stomach ulcers)
- Abx (change in colonic flora)
- Fe2+ (usually causes constipation)
- metformin
- ACE inhibitors
- statins
- olsalazine (Crohn’s)
- mefenamic acid (menstrual pain)
- laxatives (acute)
Give some examples of drug classes causing constipation.
- antimuscarinics e.g. phenothiazines, TCAs
- opiates
- Fe2+
- laxatives (chronic use - melanosis coli)
- antacids containing aluminium
- Gaviscon
- mebeverine/peppermint oil (IBS, GI spasm)
Give some examples of drug classes causing colitis (IBD, pseudomembranous, C. difficile).
- Abx
- mefenamic acid
- other NSAIDs (relapse of UC)
- methyldopa
- gold
- penicillamine
note: corticosteroids mask severe intraperitoneal pathology e.g. appendicitis (causes trauma response)
What is the trauma response caused by corticosteroids? What is the significance of this?
Pro-thrombotic state
Aldosterone release —> increased BP
Anti-inflammatory effects
Adrenaline release —> increased BP and heart rate
Therefore increased risk of CVS events
What common drugs do and do not require peri-op management?
OCP: stop at least 4wks pre-op and restart 2wks post-op (remind pt to use alternative contraception)
HRT: stop at least 4wks pre-op and restart 2wks post-op
Clopidogrel: stop 7 days pre-op
Oral hypoglycaemics: stop from day of surgery (can lead to intraoperative hypoglycaemia where S&S are masked by anaesthesia)
Herbal medicines: stop 2wks pre-op (may affect platelets)
Metformin: when iodine contrast us to be used stop on day of procedure and check U&Es at 48hrs-72hrs (renal failure)
Aspirin: do not stop (CVS protection outweighs bleeding risk)
Statins: do not stop (reduces peri-op mortality)
Beta-blockers: do not stop (sudden cessation can cause rebound angina/MI in IHD pts) UNLESS pulse is very low, causing symptoms
Corticosteroids: do not stop (sudden cessation may cause Addisonian crisis)
Warfarin: depends on indication:-
- AF: stop warfarin 5 days pre-op and check INR pre-op
- prev. DVT/PE: stop warfarin 5 days pre-op, admit day before and give high dose prophylactic SC LMWH
- prosthetic heart valve: stop warfarin 5 days pre-op, admit 2-3days before and keep INR at 2.0 and APTT 2-3
When do post-op PEs tend to occur and why?
~10days post-op when BP increases e.g. due to valsalva manoeuvre
What is the general biochemical appearance of an Addisonian crisis? What is the emergency treatment and dose?
Hyperkalaemia
Hyponatraemia
Hypoglycaemia
Hypotension
!5mg PO prednisolone = 200mg IV hydrocortisone bolus!
What is the dose of dalteparin for DVT prophylaxis? When can it be given IV?
!5,000 units SC od!
IV dalteparin ASSUMING:
- eGFR > 30
- body weight known
- APTT calculated
What is the protocol for reversal of warfarin?
EMERGENCY: give Beriplex (contains synthetic factors II, VII, IX, & X and protein C)
CAN WAIT 3hrs
What Abx should be given to cover anaerobes and C. difficile?
Metronidazole and cefuroxime
What is the emergency treatment for opiate-induced respiratory depression?
!0.4mg naloxone IV!
What are the post-op complications of opiates? How are these combatted?
Constipation
If given 3days
