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.
cardiopulmonary bypass procedure?
Aortic root cannulated
Right atrial cannula
Circuit primed and patient fully heparinised (30,000 Units unfractionated heparin) as the circuit is highly thrombogenic
Flow established through circuit
Aortic cross clamp applied
Cardioplegia solution instilled into the aortic root below cross clamp
Heart now asystolic and ready for surgery
cardiopulmonary bypass complications?
Post perfusion syndrome: transient cognitive impairment
Non union of the sternum; due to loss of the internal thoracic artery
Myocardial infarction
Late graft stenosis
Acute renal failure
Stroke
Gastrointestinal
What Pre-operative checks needs to be considered in all patients?
OP CHECS
Operative fitness: CVS comorbidities
Pills
Consent
History
Ease of intubation (neck arthritis, dentures, loose teeth)
Clexane
Site (correct and marked)
OCP/HRT and surgery?
stop 4w prior
restart 2w post op if mobile
Beta blockers and surgery?
continue as usual
AED and surgery?
continue as usual
postop give IV or via NGT if cannot tolerate oral
How many units of blood XM for AAA/gastrectomy?
AAA: 6U
Gastrectomy: 4U
duration NBM?
> =2h clear fluids
=6h SOLIDS
When are prophylactic Abx given before surgery?
15-60mins before
When are prophylactic abx used ?
GI surgery
Joint replacement
Common surgical antibiotic prophylactic regiments?
Biliary: 1.5g cef + met500mg IV
CR/appendicetomy: cef + met TDS
Vascular: co-amoxiclav 1.2g IV TDS
MRSA +ve: vancomycin
When should platelet transfusion be considered prior to surgery?
thrombocytopenia. Aim for:
>50x10^9 for most patients
50-75 if high risk of bleed
>100 if critical site surgery
When is platelet transfusion contraindicated?
Chronic BM failure
AI thrombocytopenia
Heparin induced thrombocytopenia
TTP
How to manage insulin prior to surgery in IDDM?
Reduce dose by 20% day prior to surgery
+/- stop long acting the night before
Omit AM insulin if surgery in the morning
Start sliding scale -> 5% Dex/20mmol Kcl 125ml/hr, infusion pump 50u actrapid, check CPG hourly (aim 7-11)
Post-op how is insulin managed in IDDM?
Continue sliding scale until tolerating food
Switch to SC around meal
How to manage NIDDM prior to surgery?
if fasting >10Mm treat as IDDM
Omit oral hypoglycaemics on day of surgery (am)
How to manage NIDDM post surgery?
If eating resume oral hypoglycaemics with meal
If not eating check fasting glucose on AM of surgery, start insulin sliding scale,, consult specialist team
Risks of perioperative steroids?
poor wound healing
infection
adrenal crisis
when to consider steroid cover?
if high dose steroids within last year
Major: hydrocortisone 50-100mg IV pre-med then 6-8hourly for 3d
Minor: as above but for 24 h
Risks of operating on jaundiced patients?
increased risk post oprenal failure
coagulopathy
increased infection risk
Pre-op Mx of jaundiced patients?
avoid morphine
check clotting and consider pre-op vitamin K
Give 1L NS pre-op (unless CCF)
urinary catheter
Abx prophylaxis (cef +met)
General considerations in anticoagulated patients?
avoid epidural, spinal and regional blocks
continue aspirin/clopiidogrel unless high risk of bleed (then stop 7d before)
very minor surgery can happen without stopping warfarin if INR <3.5
Protocol for emergency surgery if on warfarin?
discontinue warfarin
vit K 0.5 mg slow IV
Request FFP or PCC to cover surgery
How to manage anti coagulated patients with low thromboembolic risk e.g. AF
Stop warfarin 5 days pre-op
Need INR <1.5
Start next day after surgery
How to manage anti coagulated patients with high thromboembolic risk e.g. valves/recurrent VTE
need bridging LMWH
Stop warfarin 5d pre-op and start LMWH
Stop LMWH 12-18h pre-op
Restart LMWH 6h post op
Restart warfarin next day
Stop LMWH when iNR >2
Operative risks COPD / smoking
basal atelectasis
aspiration
chest infection
Pre-op management for smoking/COPD
stop smoking 4w prior
physio for breathing exerfises
PFTs
CXR
Examples of immediate surgical complications?
Intubation (oropharyngeal trauma)
Surgical trauma to local structures
Primary or reactive haemorrhage
Examples of early surgical complications (1d-1mo)
secondary haemorrhage
VTE
Urinary retention
Atelectasis and pneumonia
Wound infection and dehiscence
Antibiotic association colitis
Examples of late surgical complications?
Scarring
neuropathy
failure
recurrence
adhesions
Common organisms causing wound infection?
S.aureus
coliforms
Causes of post-operative ileus?
bowel handling
anaesthesia
electrolyte imbalance
Mx of post-op ileus?
IV fluids and NGT
TPN if prolonged
Early causes of post-operative pyrexia?
0-5d
Blood transfusion
Physiological (SIRS from trauma)
Pulmonary atelectasis
Infection (UTI, cellulitis, thrombophlebitis)
Drug reaction
Delayed causes of post-operative pyrexia?
> 5d post op
pneumonia
VTE(5-10d)
Wound infection (5-7d)
Anastomotic leak (7d)
Collection (5-20d)
Minimum UO, Na requirement and K requirement a day
UO- 0.5ml/kg/h
Na - 1.5-2mmol/kg/d
K - 1mmol/kg/d
Contents Na in a L bag NaCl
0.9% NaCl =9g/L
154mM NaCl
