SC01 - Anesthesiology - Pre-operative assessment Flashcards
Define micromort and microlife
Micromort:
- one-in-a-million chance of sudden death
- E.g. risk of death from GA in an emergency operation = 1 in 100,000 = 10 micromorts per operation
Microlife:
- 30 min of your life expectancy = one millionth of your life
- accumulate from day to day unlike micromorts
- e.g. Every extra 5kg overweight will cost you around one microlife a day
List 6 practices to minimize surgical risk
- Medicolegal protection
- Pre-operative risk assessment: fitness, co-morbidities, medications, anesthesia, fasting…etc
- Risk stratification
- Pre-conditioning/ pre-medication/ Cardio protection
- Surgical safety checklist/ intra-operative management plans
- Enhanced recovery after surgery (ERAS): multidisciplinary care
How to minimize medicolegal risk
Full and frank discussion before procedure
Consent
Shared decision making
Outline checklist for pre-operative risk assessment
a) Identify & optimize co-morbidities: cardiopulmonary fitness, risk of exacerbating co-morbidities (i.e. IHD, respiratory failure), specialists to optimize conditions
b) Drug history
c) Anesthetic issues
d) Fasting: >6 hours for solids, 2 hours for clear fluids
5 aims of pre-operative visit by anesthesiologist
- Risk assessment
- Plan anaesthesia and perioperative care
- Build rapport & relieve anxiety
- Instructions and pain management
- Pre-medication for cardio-protection
Outline history taking questions for pre-operative assessment
- Functional/ exercise capacity (poor capacity = high cardiopulmonary complication risk)
- Medical history:
- Long-term co-morbidities, cardiac and metabolic diseases…etc - Drug history:
- Drugs to stop or titrated, recreational drugs - Surgical history:
- Previous surgeries and complications
- Indwelling devices, implants…etc - Anesthesia history
- Prior anesthesia
- Complications - Risk of delayed gastric emptying:
- Trauma, pain, drugs, emergency surgery…etc - Plan post-operative analgesia
- Consent for anesthesia, worries, requests
Outline long-term co-morbidities that increase risk of surgical mortality
PVD/ CVA/ CHF/ MI/ renal disease - Increase risk of death 1.5x
TIA/ Angina - Increase risk of death 1.2x
Diabetes - Increase risk of death 5x
How does DM increase risk of intra-operative death
Heart disease or stroke
Pulmonary thromboembolism
Perioperative infection (impaired leukocyte function, including altered chemotaxis and phagocytic activity)
Outline drugs that need to be stopped before anesthesia
Oral hypoglycaemics
Anticoagulants
?aspirin (increase risk of bleed but lower CVS events)
Oral contraceptives
TCM
Recreational drugs
Titrated: Digoxin, anti-convulsants
List possible anesthetic complications
Post-operative nausea and vomiting (PONV)
Delayed emergence from anesthesia
Anaphylactic reactions/ allergies
Airway/ Intubation problems
Genetic problems
- Pseudocholinesterase deficiency (abnormal metabolism of drugs)
- Malignant hyperthermia (family history)
- Nerve damage
List P/E for pre-operative assessment
- General appearance
- Full CVS, Respiratory exam
- Inspection for indwelling devices e.g. dentures, prosthetic heart valves, pacemakers, etc.
- Aerobic capacity/ exercise capacity/ functional status
FU with specific Ix
List methods of pre-operative risk stratification
ACC/ AHA guideline: Cardiac risk stratification for non-cardiac surgery; Clinical predictor of increase peri-operative cardiovascular risk
ASA classification: Patient surgical risk stratification
List types of cardio-protection/ pre-conditioning medical therapy before surgery
1) Aspirin (may increase bleed)
2) Beta-blockers (may increase stroke and HT risk post-op)
3) Statins
4) Glycemic control
Outline the ASA classification for operative risk
Class I - A normally healthy individual
Class II - A patient with mild systemic disease
Class III - A patient with severe systemic disease that is not incapacitating
Class IV - A patient with incapacitating systemic disease that is a constant threat to life
Class V - A moribund patient who is not expected to survive 24h with or without surgery
Types of biases that influence surgical decision making
Cognitive biases (how we frame things when communicating to patients):
Anchoring bias (rely too heavily on the first piece of information offered)
Availability bias (relies on immediate examples that come to a given person’s mind)
Confirmation bias (look for evidence to support the preconceived idea)
Representative biases
Consensus opinion (acceptance of obviously wrong answers that are socially more acceptable)
“Herd instinct”
