ACC Flashcards
what three main things present a risk to the patient undergoing surgery?
1) surgery itself - damage to structures, blood loss, complications
2) effects of anaesthesia
3) pre-existing disease
list some possible intra-operative problems that can happen
- fluid balance
- hypoxia
- pain
- PONV
- hypothermia
- anaphylaxis
- PE
- death
what “centre” controls PONV? how does it work?
the vomiting centre - linked to other parts of the brain responding to different stimuli, via different receptors.
- inner ear –> cerebellum (H1)
- emotion (fear) –> higher centres
- blood-borne emetic –> chemoreceptor trigger zone (5HT-3, D2, H1)
- pharynx/GI tract –> solitary tract nucelus (5HT-3, D2, H1)
blood borne emetics / GI tract interact between each other.
all these different pathways act on vomiting centre, mediated by 5HT-3, D2
I think?? maybe look this up to actually understand it
give an example of an antiemetic that works on serotonin pathways? indications?
ondansetron - useful for both PONV and for vomiting post acute opioid administration
give an example of an antiemetic that works on histamine (H1) pathways? indications?
cyclizine
commonly used for travel sickness
can cause tachycardia
give examples of antiemetics that work on dopamine (D2) pathways? indications?
domperidone = premedication if at risk of PONV metoclopramide = long term opioid use (counteracts gastric stasis procholperazine = vertigo
what 5 steps make up pre-op preparation?
1) optimise medical conditions
2) adjust medication
3) check Ix
4) check wt
5) EXPLAIN AND CONSENT
explain the ASA grading system
1) healthy individual
2) mild systemic disease not limiting activity
3) severe systemic disease limiting activity but not incapacitating
4) incapacitating systemic disease, life threatening
5) emergent case - expected survival <24hrs without surgery
(6 = brain stem dead, for organ retrieval)
how do the 5 ASA grades related to predicted mortality?
1 = 0.05% 2 = 0.5% 3 = 5% 4 = 25% 5 = 50%
what key conditions do you want to know about when asking the anaesthetic history in pre-op?
pts prev. experience and FHx relevant. * malignant hyperpyrexia * suxamethonium apnoea also: - previous airway problems - PONV (ask about travel sickness etc too)
what is malignant hyperpyrexia?
inherited skeletal muscle disorder that can be triggered by volatiles and suxamethonium.
causes hyperkalaemia, hypoxia, temperature, rhabdomyolysis.
can reverse with dantralene.
what is suxamethonium apnoea?
patient doesn’t have the enzyme to break down suxamethonium - use propofol instead.
inherited disorder of acetylcholinesterase.
what allergies is it important to ask about in pre-op assessment?
anaesthetic agents, analgesics, abx, latex, EGGS (propofol)
what is the protocol for peri-op adjustment if a patient is on: ACE inhibitors ?
stop as the anaesthetic will drop BP
what is the protocol for peri-op adjustment if a patient is on: angiotensin 2 receptor blockers ?
stop 24hrs before
what is the protocol for peri-op adjustment if a patient is on: ranitidine ?
increases pH so if aspiration occurs it’s less bad - continue
what is the protocol for peri-op adjustment if a patient is on: warfarin ?
stop.
if pt has AF use LMWH.
if thrombophilia/metallic heart valve (?) = stop 3-5 days before, use bridging protocol.
what is the protocol for peri-op adjustment if a patient is on: inhalers?
continue - should be brought with the patient into the anaesthetic room, and taken round to recovery.
what is the protocol for peri-op adjustment if a patient is on: clopidogrel?
stop 5 days before
what is the protocol for peri-op adjustment if a patient is on: beta blockers?
continue
what is the protocol for peri-op adjustment if a patient is on: PPIs?
continue
what is the protocol for peri-op adjustment if a patient is on: aspirin?
stop high does (200mg) - can continue 75mg only if spinal/epidural
what is the protocol for peri-op adjustment if a patient is on: steroids?
continue
what is the protocol for peri-op adjustment if a patient is on: insulin/oral hyperglycaemia?
insulin dependent people need a variable rate insulin infusion (sliding scale). avoid starving them - place first on the list!