Anaesthetics- Fundamentals of Anaesthetic Curriculum Flashcards
What are the different peri-operative risk scoring systems?
ASA and POSSUM.
What is the ASA peri-operative risk scoring system?
ASA 1: healthy patient.
ASA 2: mild systemic disease; no functional limitation.
ASA 3: moderate systemic disease; have functional limitation.
ASA 4: severe systemic disease that is a constant threat to life.
ASA 5: moribund patient; unlikely to survive 24hrs, with or without treatment. Postscript E: indicates emergency surgery.
What is POSSUM scoring?
Risk prediction.
Enter patient physiological and operative variables.
Mortality and morbidity risk:
pre-operative = risk discussion
peri-operative = need for invasive monitoring?; post-operative = over 5% mortality risk should go to HDU/ITU post-operative.
Why is there a nil by mouth policy before surgery, and what is the usual guidance?
Reduce aspiration risk. Food: 6hrs; water: 2hrs; caveat: reflux, obesity, slow gastric transit e.g. trauma.
How do you prescribe opioids, e.g. morphine?
Dose
Form- oral/IV/subcut/IM
Strength (where appropriate)
Total quantity or dosage units of the preparation in words and figures- total amount that the patient will take away
For instalment prescriptions, specify the instalment amount and instalment interval.
Handwritten.
Your signature and date (include bleep no.)
List 5 anti-emetic drugs.
Ondansetron
Cyclizine
Dexamethasone
Metoclopramide
Prochlorperazine
What is the mechanism of action, dose, route, and side effects of ondansetron?
Mechanism of action = 5HT3R antagonist. Side effects = bradycardia; long QT syndrome. Dose/route = 4-8mg TDS; PO/IV.
What is the mechanism of action, dose, route, and side effects of cyclizine?
[*not in lecture but in previous flashcards]
Mechanism of action = H1 R antagonist. Side effects = tachycardia; anti-cholinergic. Dose/route = 50mg TDS; PO/slow IV/IM.
What is the mechanism of action, dose, route, and side effects of dexamethasone?
[*not in lecture but in previous flashcards]
Mechanism of action = corticosteroid. Side effects = hyperglycaemia; perineal ‘burning’ (transient). Dose/route = 4-8mg BD; IV.
What is the mechanism of action, dose, route, and side effects of metoclopramide?
[*not in lecture but in previous flashcards]
Mechanism of action = central DA2 R antagonist. Side effects = extrapyramidal. Dose/route = 10mg TDS; PO/IV.
What is the mechanism of action, dose, route, and side effects of prochlorperazine?
[*not in lecture but in previous flashcards]
Mechanism of action = DA antagonist. Side effects = extrapyramidal; long QT syndrome. Dose/route = 12.5mg BD; IM.
Explain the WHO pain ladder.
Step 1: non-opioid, e.g. aspirin, paracetamol, or NSAID, ±adjuvant.
Step 2: weak opioid, for mild to moderate pain, e.g. codeine, ±non-opioid, ±adjuvant. [side effects- nausea, constipation]
Step 3: strong opioid, for moderate to severe pain, e.g. morphine, ±non-opioid, ±adjuvant. {oral morphine first, then push button to administer morphine]
Case 1: a poorly controlled asthmatic patient on oral steroids presents for emergency manipulation of a fractured radius, he is slightly breathless and wheezy at rest, describe your management.
Management of severe bronchospasm outside of theatre: - BTS guidelines
A,B,C.
O2: start high flow oxygen and gain IV access.
Salbutamol nebuliser 2.5-5mg.
Hydrocortisone 100mg IV 6-hourly or prednisolone orally 40-50mg/day.
Ipratropium nebuliser 0.5mg 4-6-hourly; IV salbutamol if not responding (250mcg slow bolus then 5-20mcg/min).
Theophylline/aminophylline- [aminophylline less commonly used b/c narrow therapeutic window- death if given too quickly]
Magnesium 2g IV over 20 minutes.
In extremis (decreasing conscious level or exhaustion), adrenaline may be used: nebuliser 5ml of 1 in 1,000; senior clinician only: IV 10mcg (0.1ml 1:10,000) increasing to 100mcg (1ml 1:10,0000) depending on response.
What are the triggers of anaphylaxis?
Stings (wasp, bee, etc.)
Nuts
Food, e.g. milk, fish, chickpea, crustacean, etc.
Antibiotics, e.g. penicillin, cephalosporin
Anaesthetic drugs, e.g. suxamethonium, vecuronium
Other drugs, e.g. NSAID, ACEi, gelatins
Contrast media, e.g. iodinated Other, e.g. latex, hair dye, hydatid
How is anaphylaxis recognised?
ABCDE approach.
Airway problems:
- airway swelling, e.g. throat and tongue swelling (pharyngeal/laryngeal oedema);
- difficulty breathing and swallowing
- hoarse voice
- stridor (high pitched inspiratory noise caused by upper airway obstruction).
Breathing problems:
- shortness of breath
- increased respiratory rate
- wheeze
- tired
- confusion caused by hypoxia
- cyanosis (appears blue), usually a late sign
- respiratory arrest
Circulation problems:
- signs of shock- pale, clammy
- increased pulse rate (tachycardia)
- low blood pressure (hypotension)
- feeling faint, dizzy, collapse, decreased conscious level or loss of consciousness
- myocardial ischaemia and ECG changes even in individuals with normal coronary arteries
- cardiac arrest.
Disability.
Exposure
- Rash
- Swelling - angioedema
How is anaphylaxis managed?
Call for help.
Lie patient flat. Raise patient’s legs.
Adrenaline.
When skills and equipment available:
- establish airway
- high flow oxygen
- IV fluid challenge
- IV chlorphenamine
- IV hydrocortisone
Monitor: -pulse oximetry, ECG, BP
How is anaphylaxis diagnosed?
Look for: -acute onset of illness -life-threatening airway and/or breathing and/or circulation problems -and usually skin changes
What are the triggers for giving a blood transfusion?
Hb: >90
How does the NEWS work?
Like many existing EWS systems, based on simple scoring system in which a score is allocated to physiological measurements already undertaken when patients present to, or are being monitored in hospital.
6 simple physiological parameters form the basis of the scoring system:
respiratory rate,
oxygen saturations,
temperature,
systolic blood pressure,
pulse rate,
level of consciousness.
Score allocated to each measure. Magnitude of score reflecting how extreme the parameter varies from the norm.
Score is then added up (uplifted if on oxygen).
Over 7= high
5-6 = Medium
1-4 = Low
Routinely measured in hospitals and recorded on clinical chart.
What are the indications for an arterial blood gas (ABG) sample?
Obtain and interpret oxygenation levels.
Potential respiratory derangements.
Potential metabolic derangements.
Monitor acid-base status.
Carboxyhemoglobin in CO poisoning.
Assess lactate.
Preliminary results for electrolytes and haemoglobin.
Conducted as a one off sample or repeated sampling to determine response to interventions.
What are the contraindications for an arterial blood gas (ABG) sample?
- Local infection
- Distorted anatomy
- Presence of arterio-venous fistulas
- Peripheral vascular disease of the limb to be sampled
- Severe coagulopathy or recent thrombolysis.
What are the possible sampling errors in an arterial blood gas (ABG) sample?
- Presence of air in the sampl
- Collection of venous rather than arterial blood
- An improper quantity of heparin in the syringe, or improper mixing after blood is drawn
- Delay in specimen transportation.
What are the possible complications related to arterial blood sampling?
Haematoma
Nerve damage
Arteriospasm or involuntary contraction of the artery
Aneurysm of artery- split two layers of intima with needle
Fainting or a vasovagal response.
What criteria defines sepsis?
Which 2 answers are used to define sepsis?
a) HR > 90 b) HR > 100 c) temp >38C d) temp >39C
Two or more of:
- Temp >38 C or <36 C
- Resp rate >20
- WCC >12 or <4
- Heart rate >90 bpm
HR > 90
Temp >38C
Which arteries can be sampled for ABG analysis?
a) radial b) ulnar c) carotid d) dorsalis pedis e) femoral
All apart from carotid.
What does peri operative care include?
Pre operative
Intra operative
Post operative
How to assess and manage comorbidities perioperatively?
Diabetes
IHD
Asthma
COPD
Anticoagulants
Sickle cell
Disease optimisation and control
What factors determine which pre operatvive investigations need to be done?
Patient comorbodities/medication
Complexity of surgery + haemorrhage risk- minor
What criteria allows a surgery to be a day surgery procedure [go home the same day, hospital stay of max 24 hr?]
Social- carer at home, good home setup, patient willing
Medical- fit enough to go home, comorbidities, obesity, stable chronic disease
Surgical- what are the risks of complications, can post op symptoms be controlled at home, will pt be mobile after surgery
When should further investigations be considered?
Respiratory disease
Lung function tests:
Do baseline ABGs
FEV1<40%- high predictor for postoperative ventilation- ITU
COPD= important to figure out baseline, so you know when to be concerned
Blood test abnormalities: Anaemia, Renal dysfunction
Cardiac:
Depending on condition
ECG- assess ischemia, arrhythmia, baseline
Echo- LV function and valves
Stress echo- dynamic changes in ischaemia- exercise tolerance test or if unable chemically using dobutamine
How is an anaesthetic history different from an normal history? Components of anaesthetic history + exam?
- Previous surgery/general anaesthetic
- FH of previous general anaesthetic- malignant hyperpyrexia
- PMH- comorbidities, exercise tolerance
- m, al
- SH- smoking, alcohol, recreational drugs
- t
- Airway assessment
- Mallampati score
- Neck movements
- NBM?
What is the Mallampati score?
Measures airway access
High predictor for difficult airway, along with neck movement
Stage 1 best, Stage 4 worst
Stage 1: Can see soft palate clearly + whole uvula
Stage 2: Can see whole uvula, but not soft palate
Stage 3: Can see base of uvula
Stage 4: Can’t see uvula at all
What are the types of airway adjuncts and devices?
When are they used and what are their parts?
- Oropharyngeal airway
- get tongue out of way so opens airway + bag mask can work more easily
How do you choose correct size of oropharyngeal airway?
Corner of mouth to angle of mandible
- Bag mask valve
- only use in apneic patient= not breathing at all
- Parts: Facemask, valve, compression chamber, oxygen reservoir]
Connect to oxygen outlet + ensure outlet is on high flow- can provide 99-100% O2
- Supraglottic airway
Sits at level of vocal cords- just above
Not definitive airway
- Endotracheal tube
Parts- cuff [balloon that inflates- goes inside trachea]
- black line- level of vocal cords- so doesn’t end up in bronchiole
Pilot balloon that inflates cuff- by putting air in
Can connect other end to bag mask valve or other equipment
Definitive airway
What is a definitive airway?
Cuffed tube IN TRACHEA- below vocal chords
Endotracheal tubes
WHO checklist
Reduces surgical mortality by 40%
What needs to be considered for VTE prophylaxis?
What would you do to mitigate risk?
Mobility
Risk factors
Bleeding risk
Summary of anti emetic drugs- table
Why are anti emetics used perioperatively?
Nausea = side effect of morphine analgesia
Which antiemetics are most commonly used?
What does this show?
How would you treat it?
Tension pneumothorax
Needle aspiration
[Acute b/c tension obliterated venous return]
How to manage post operative sepsis?
What about if cardiac decompensation?
Within 3 hours:
IV fluid- crystalloid- 30ml/kg [hypotension/high lactate]
IV antibiotics
[O2]
Blood cultures [before antibiotics given]
Lactate levels [>4 mmol/L is bad]
[Urine output]
Within 6 hours- if decompensation
Vasopressors [if persisting hypotension- maintain >65 mmHg]
Reassess volume and tissue perfusion
Repeat lactate
