Anaesthesiology - Pre-operative assessment Flashcards
Define checklist for pre-operative assessment clinic (PAC) (Day 0 - Day of surgery)
Aim of pre-op assessment
* Formulate anaesthetic plan + analgesic regimen
* Optimize patient condition
* Determine fitness for surgery
* Decide post-op placement
* Plan fasting, premedication
* Establish rapport
Consist of:
* Taking a history (past and present) from patient, relatives, care-provider
* Physical examination
* Order/review appropriate investigation
* Explain anaesthetic plan
* Obtain consent with explanation of risks
List basic physical exams for pre-operative assessment
Airway assessment (including oro-facial exam)
Full respiratory exam
Full circulatory and cardiac exam
Sites of vascular access
Other system exams if chronic disease
Define CVS history relevant to pre-operative assessment
Primary disease and end organ involvement, enquire specifically about symptoms of:
* Ischemic heart disease, frequency + severity + predictability of angina
* Heart failure-increased risk of peri-op cardiac morbidity + mortality
* HT-treatment and control
* Valvular heart disease - AS in elderly, congenital heart disease into adulthood
* Conduction defects, arrhythmias
* PVD, previous DVT, PE
* PCI/pacemaker/anticoagulants
Define CVS risk factors associated with poor surgery outcome
Previous history of MI: further infarction, peri-op risks decreases as time elapsed since original event
Uncomplicated MI with normal exercise tolerance: elective surgery may need to be delayed by 6-8weeks
Complicated MI, infarction, residual angina, arrhythmias: need cardiac assessment before exam
Hypertention:
* Moderate SBP 160-179 mmhg, DBP 100-109 mmHg: consider review of treatment. If unchanged requires close monitoring to avoid swings during surgery and anaesthesia
* Severe SBP > 180 mmHg, DBP > 109 mmHg: postpone elective surgery until lower than 180/110 because risk of myocardial ischemia, arrhythmias + Intracranial haemorrhage
Define respiratory diseases relevant to pre-operative assessment
Asthma, COPD, infection, restrictive lung disease: increase risk of peri-operative chest infection
Acute URTI: anaesthesia and
surgery may be postponed unless it is a life threatening condition
Smoking: higher risk of post-op. respiratory crises
OSA: increase risk of respiratory depression
Assess exercise tolerance: Prediction of post-op morbidity and mortality
- Subjective measurement: e.g. Can you run for a bus? Can you do housework?
- Objective measurement: metabolic equivalents of
activity (MET); New York Heart Association (NYHA) classification of cardiac function of specific activity scale
Outline Metabolic Equivalent of Activity (MET)
Outline the New York Heart Association (NYHA) classification of cardiac function of specific activity scale
List chronic diseases associated with adverse outcome in surgery (excluding cardiovascular and respiratory diseases)
- Indigestion, GERD: increase risk of regurgitation and aspiration pneumonia)
- Rheumatoid arthritis: difficult to position deformed joints, C-spine subluxation affects airway, chronic anemia, S/E from drugs
- DM: IHD, renal dysfunction, neuropathies, infection, orthostatic hypotension
- Neuromuscular diseases: chest infection, poor bulbar function cause aspiration
- Chronic renal failure: anemia, electrolyte abnormality, altered drug excretion
- Hepatic diseases: coagulopathy, opioid metabolism
Relevant anesthetic history in pre-operative assessment
Relevant family history
Prior problem with anaes:
- Nausea and vomiting, awareness, jaundice, delayed recovery,
prolonged hypotension
- History of difficult intubation
- History of delayed recovery
- Difficult IV access, bleeding
- Potential anaes. access problems e.g. cardiac/pulmonary/spine
Family history:
- MH, Psuedocholinesterase deficiency, previous ICU admission
Relevant drug and allergy history in pre-operative assessment
Smoking: decreases ciliary function
Stopping 8 weeks improve airway
Stopping 2 weeks decreased airway irritability
Stopping 2 days decreases CO level
Alcohol
Enzyme induction-drug tolerance
Post-op alcohol withdrawal syndrome
Drug abuse
Difficult IV
HBV, Hep B, Hep C carrier
Drug withdrawal syndrome post-op (cocaine)
Pregnancy
X Ray in first trimester
First trimester-greater chance of abortion (though risk of spontaneous abortion is high, elective suxamethonium use during second trimester)
increased risk of regurgitation and aspirations due to increased intra-abdominal pressure and delayed gastric emptying
Define the American Society of Anaesthesiologist
Classification for surgical outcome
Correlates well with outcome
1. A normal healthy patient
2. A patient with mild systemic disease
3. A patient with severe systemic disease
4. A patient with severe systemic disease that is a constant threat to life
5. A moribund patient who is not expected to survive without the
operation
Outline the anesthetic pre-operative management plan
- Fasting: reduce gastric content and risk of aspiration
Clear fluids 2hrs
Breast milk 4hrs
Light meal 6hrs - Define type of anaesthetic and consent
- Any consultation + extra investigations of medical diseases
- Adjust ongoing medications
- Premedication
- Post-operative placement deoending on:
premorbid status
nature and length of operation
intraop and postop events
Plans to reduce regurgitation/ aspiration
assert fasting time
non diabetic patient: drinking fluids with carbohydrate and protein up to 2hrs before GA induction suffer less pre-op nausea and dehydration
Rapid sequence intubation for emergency/ high-risk patients
prophylaxis -chemical control of gastric volume and acidity for pt. with frequent GERD symptoms:
a. antacids-neutralize acidity
b. H2 blockers/PPI - decreases stoma acidity
c. metoclopramide-seldom used for gastric motility
d. NG tube suction
List pre-medications given during pre-operative preparation
- Pain relief: IV Midazolam, Fentanyl/ ketamine; Acetaminophen, Gabapentine for post-op pain
- Sedation, anxiolysis: Oral/ IV Midazolam, Nasal Dexmetomidine
- DVT prophylaxis
- Regurgitation and aspiration prophylaxis: Antacids, H2 blockers, PPI, Metoclopromide, Anti-emetics
- Drug and pre-existing disease – DM, HT, herbal medicine, psychiatric drugs, drug abuse, anti-coagulants
- Airway maniputation: Glycopyrolate (inhibit salivary gland and respiratory secretions)
- Pacemaker programming
- EMLA cream for paeds
- Second trimester pregnancy: Sodium citrate+H2 blockers
Aims of pre-operative assessment
- Reduce hospital stay, bed occupancy, economic and psychological impact
- Identify patient’s at low risk of complications during anaesthesia and surgery - ASA 1, 2 patients, uncomplicated surgery - as day surgeries
- Identify medical problems and improve management/ investigations
- Reduce cancellation of intended surgery after admission due to fitness/ medical problems
- Obtain consetn
Time between surgery and PAC should not exceed 3 months (4 - 6weeks optimal)
List common, uncommon and rare risks of anesthesia
Common:
bruising and attempts at IV access
sore throat
headache
dizziness
PONV
itching(opioids)
retention of urine
Uncommon:
dental damage
chest infection
muscle pain (positioning, Suxamethonium rarely used except in emergency)
an existing condition worsened-myocardial infarct, heart failure
awareness during GA
Rare:
allergy to anaesthetic drugs
eye injury-particularly if prone
nerve damage (tourniquet, surgery, positioning, regional)
hypoxic brain damage
death (most commonly Myocardial Infarction)
