Perioperative Flashcards
Which heparin regime should the surgeon ask for prior to cross clamping in vascular surgery?
3,000 units of systemic heparin 3-5 minutes prior to cross clamping (prevent intra-arterial thromboses)
Advantages of LMWH?
Better bioavailability
Lower risk of bleeding
Longer half life
Little effect on APTT at prophylactic dosages
Less risk of HIT
Complications of LMWH?
Bleeding
Osteoporosis
Heparin induced thrombocytopenia (HIT): occurs 5-14 days after 1st exposure
Anaphylaxis
Features of lidocaine toxicity?
Initial CNS over activity then depression as lidocaine initially blocks inhibitory pathways then blocks both inhibitory and activating pathways. Cardiac arrhythmias.
What does lidocaine interact with?
Beta blockers, ciprofloxacin, phenytoin
How does bupivacaine work?
Bupivacaine binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.
difference between bupivacaine and lidocaine?
longer duration of action than lignocaine and this is of use in that it may be used for topical wound infiltration at the conclusion of surgical procedures with long duration analgesic effect.
When is bupivacaine contraindicated?
regional block as cardiotoxic
What is the LA of choice for regional anaesthesia?
prilocaine (non cardiotoxic)
lignocaine dose plain and with adrenaline?
3mg/Kg, 7mg/Kg
Bupivacaine dose plain and with adrenaline?
2mg/Kg, 2mg/Kg
Prilocaine dose plain and with adrenaline?
6mg/Kg, 9mg/Kg
What are adult maintenance fluid requirements?
Na 50-100 mmol/day and K 40-80 mmol/day in 1.5-2.5L fluid per day.
When should patients for elective surgery be given carbohydrate rich drinks?
Patients for elective surgery should be given carbohydrate rich drinks 2-3h before. Ideally this should form part of a normal pre op plan to facilitate recovery.
Which drugs impair wound healing?
Non steroidal anti inflammatory drugs
Steroids
Immunosupressive agents
Anti neoplastic drugs
what are the stages of wound healing?
Haemostasis,
Inflammation,
Regeneration
Remodelling
Keloid vs hypertrophic scar?
Keloid extends beyond boundaries of wound
Hypertrophic confined to boundaries of original wound
Factors affecting wound healing?
DID NOT HEAL
D iabetes
I nfection, irradiation
D rugs eg steroids, chemotherapy
N utritional deficiencies (vitamin A, C & zinc, manganese), Neoplasia
O bject (foreign material)
T issue necrosis
H ypoxia
E xcess tension on wound
A nother wound
L ow temperature, Liver jaundice
What can reverse IV heparin?
protamine sulfate
How long does it take UFH to be cleared from circulation?
2h
When will patients with metallic heart valves stop UFH?
6h before surgery
administration of what may help to identify parathyroid glands?
methylene blue IV
Which vessel is the best conduit for a coronary artery bypass?
internal mammary artery
indication for cardiopulmonary bypass?
Left main stem stenosis or equivalent (proximal LAD and proximal circumflex)
Triple vessel disease
Diffuse disease unsuitable for PCI
The guidelines state that CABG is the preferred treatment in high-risk patients with severe ventricular dysfunction or diabetes mellitus.