Peri-Op Flashcards
What are the indications for Fluid resuscitation?
- Systolic BP <100mmHg
- HR >90bpm
- Cap refill >2s/cold peripheries
- RR >20bpm
- EWS >/= 5
- Passive leg raise suggests need
How much fluid do you give for Resus?
500ml crystalloid (containing Na+) within 15minutes
- If elderly or have complex co-morbidities (HF, renal failure), give 250 rather than 500
- If patient still hypovolaemic, can give another bolus and then reassess using ABCDE.
- Can give up to 2000ml after which need to seek expert help.
What is the daily Fluid, Electrolyte and Glucose requirement of an adult?
- Water: 20-30ml/kg/day
- Na+: 1mmol/kg/day
- K+:1mmol/kg/day
- Glucose 50-100g/day
What are examples of ongoing abnormal fluid/electrolyte losses?
- vomiting and NG tube lossess
- diarrhoea
- ongoing blood loss
- stoma loss
- sweating/fever
- excessive urinary loss
What is the optimal time for stopping smoking prior to surgery? and what is the minimum time to stop smoking?
6 weeks optimally. but minimum of 7 days prior to surgery required
Describe the ASA grade and what does it correlate with?
- I - Normal healthy patient
- II - Mild systemic disease
- III - severe systemic illness, a functional limitation of their activity
- IV - severe systemic illness that is a constant threat to life
- V - moribund
Correlates with their risk of post-op complications and absolute mortality
How do you assess the ease of intubation in patients going for surgery?
Using the Mallampati classification:
- Class I: soft palate, uvula, fauces, pillars visible
- Class II: soft palate, uvula, fauces visible
- Class III: soft palate, base of uvula visible
- Class IV: only hard palate visible
When should patients be put on NBM before the surgery?
Stop eating 6 hrs before (stop clear fluids 2 hrs before)
What are the drugs to stop before surgery? How early before the surgery should each of these drugs be stopped?
CHOW:
- Clopidogrel - stop 7 days before surgery (aspirin and dipyramidole can be continued).
- Hypoglycaemics
- Metformin should be stopped on morning of surgery
- All others should be stopped 24hrs before
- Patients should be put on insulin sliding scale
- Oral contraceptives - stopped 4 weeks before surgery due to DVT/VTE risk.
- Warfarin
- Stopped 5 days before surgery
- LMWH started 1-2days before surgery (bridge)
- INR needs to be <1.5 before surgery
What is the guidelines for Warfarin reversal?
If person has major bleeding:
- stop warfarin
- Urgent IV Vitamin K (phytomenadione) +/- Prothrombin complex concentrate OR
- Fresh frozen plasma 15ml/kg
If INR >8.0 but no bleeding/minor bleeding:
- Stop warfarin
- IV Vit K (0.5-1mg) or oral (5mg)
- Restart warfarin when INR <5.0
INR 6-8 but no bleeding/minor bleeding:
- stop warfarin
- Restart when INR <5.0
INR <6
- stop/reduce warfarin
- restart when INR <5.0
For surgery:
- If INR 2-3 day before surgery - Give IV/oral Vit K
- If INR >1.5 on surgery day - defer surgery or give Prothrombin complex concentrate.
What are the drugs to start before surgery?
VTE prophylaxis:
- mechanical devices - TED Stockings, pneumatic compression
- Drugs -
- LMWH (SC injection) - 20-40mg one dose before surgery
Antibiotic Prophylaxis
- Colorectal, HPB and Lower GI surgery:
- Gent + metronidazole (same for penicillin allergy)
- Upper GI surgery, pancreactectomy:
- Co-amoxiclav (Gent + Metronidazole if penicillin allergic)
- Orthopaedics and Vascular surgery:
- Co-amox (Teico + Gent if penicillin allergic)
Antiemetics - esp if hx of PONV
What is the management of DM before surgery?
T1DM
- Avoid long acting insulin and omit morning dose of inulin
- Commence insulin sliding scale + 5% dextrose with potassium.
T2DM
- Diet controlled - avoid glucose containing solutions, check capillary glucose regularly
- Tablet controlled - omit all oral hypoglycaemics on day of surgery. Start insulin sliding scale + 5% dextrose pre-op.
What are the complications of general anaesthesia
- Pain
- PONV
- anaphylaxis to anaesthetic agents
- Cardiovascular collapse
- Resp depression
- Aspiration pneumonitis
- Damage to teeth
- sorethroat/laryngeal damage
- hypotherma
- hypoxic brain injury
- embolism
Some complications of surgery
Pulmonary - pulmonary collapse, pulmonary infection, resp failure
Cardiac - MI, heart failure, arrhythmias, shock
Urinary complications - renal failure, UTI, urinary retention
Cerebral complications - CVA, post-op delirium
Wound complications - infection, dehiscence
In general, what is the mechanism of action of anaesthesia?
- Increase sensitivity of GABA and Glycine channels to Cl-
- Inhibit NMDA receptors and Nicotinic Ach receptors - reduces excitatory NMDA and ACh causing depolarisation
What is the benefit of IV anaesthetics (propofol, ketamine) over Inhalational (Sevoflurane, isoflurane, NO)?
- faster induction of anaesthesia with IV compared to inhalational - bypassess the excitatory/aggression phase of surgical depth
- Recovery is faster with IV - because fat and muscle can be a reservoir for inhalational agents and can redistribute into the CNS during anaesthetic withdrawal
What is the mechanism of action for Local anaesthetics (eg: lidocaine, bupivacaine)?
Block fast acting Na+ Channels
What are the signs of LA toxicity?
Early:
- Numbness/tingling of tongue/metallic taste on tongue
- Tinnitus
- Anxiety
- Lightheadedness
Late:
- LOC
- Convulsions
- Cardiovascular collapse
- Apnoea
How do you treate LA toxicity?
- Secure airway
- IV fluids - to treat hypotension
- Anti-arrhythmics
- Benzodiazepines - to treat seizures
What are some of the post-op analgesics that can be used?
- opiods - morphne, fentanyl, tramadol, codeine
- NSAIDs
- Paracetamol
- Continuous Wound infusion - for big ops
What is the mechanism of action of Opiods?
- Act on miu, kappa, delta opioid receptors (GiPCRs)
- Binding to these receptors causes K+ channels opening resulting in hyperpolarisation of postsynapic membrane
What are the adverse reactions of opioids?
- Miosis
- Nausea and vomiting
- Resp depression
- Constipation
- Confusion
- Psychosis
- Coma
What are the side effects of NSAIDs?
- renal impairment - AKI
- Gastric ulcers
- asthmatic bronchospasm
- skin reactions - steven johnsons syndrome
- Allergy
What are the indications of RBC blood transfusion?
- Hb <70g/L - target of 70-90g/L after transfusion
- For those who have: recent haemorrhage, ACS, blood transfusion for chronic anaemia.
Indication for platelet transfusion?
- clinically significant bleeding AND
- platelet count <30x10^9
