Fundamentals of Anaesthesia - Chapter 1 Flashcards
Definition of one MET?
1 MET equates to 3.5 millilitres of oxygen per kilogram body weight per minute
How many METs for the following?
- Walk 100 metres on level ground
- Climb a flight of stairs or walk up a hill
- Strenuous exercise
1 MET - walk 100 metres on level ground
4 MET - climb a flight of stairs or walk up a hill
> 10 MET - strenuous exercise
Increased perioperative risk below if functional capacity is below how many METs?
A functional capacity corresponding to < 4 MET (unable to climb a flight of stairs) is associated with increased perioperative risk.
Factors associated with difficulty in mask ventilation (5)?
Obesity Beard Edentulous Snoring Age > 55
Grades of laryngoscopy 1-4?
Grade 1: whole of glottis visible
Grade 2: glottis incompletely visible
Grade 3: epiglottis but not glottis visible
Grade 4: epiglottis not visible
Frequency of difficult intubations? % not predicted?
1 in 65 are difficult
20% no predicted
Mallampati classes 1-4?
Class 1: faucial pillars, soft palate and uvula visible
Class 2: faucial pillars and soft palate visible, uvula
masked by base of tongue
Class 3: only soft palate visible
Class 4: soft palate not visible
Wilson risk factors (5)?
Obesity Restricted head and neck movements Restricted jaw movement Receding mandible Buck teeth
Tests of neck and jaw movement (4)
Flex chin to chest
Limitation of extension - normal >35 degrees
Reduced mouth opening (less that 2 fingers)
Reduced inter-incisor distance (<3.5cm)
Normal angle of atlanto-occipital extension?
> 35 degrees
Normal mouth opening?
Normal inter-incisor distance?
Normal mouth opening - > 2 fingers
Normal inter-incisor distance- >3.5cm
How is thyromental distance measured?
Below what distance predicts a difficult airway?
Distance between the chin and the thyroid notch with the neck fully extended.
A distance of < 6.5 cm (about three finger breadths) predicts difficulty.
How is sternomental distance measured?
Below what distance predicts a difficult airway?
It is the distance from the suprasternal notch
to the chin with the neck fully extended.
A distance of < 12 cm predicts difficulty.
How is hyomental distance measured?
Below what distance predicts a difficult airway?
The hyomental distance is that from the chin to the hyoid bone. A distance of < 4 cm (about two finger breadths) predicts difficulty.
ASA1 definition
A normal healthy patient
ASA2 definition
A patient with mild systemic disease
ASA3 definition
A patient with severe systemic disease
ASA4 definition
A patient with severe systemic disease that is a constant threat to life
ASA5 definition
A moribund patient who is not expected to survive without the operation
ASA6 definition
A declared brain-dead patient whose organs are being removed for donor purposes
Mendelson’s syndrome?
Pneumonitis secondary to aspiration of gastric acid in pregnant patients
Starvation guidelines - adults?
- Clear fluids
- Food/milky drinks
Adults
- Clear fluids and water up to 2 hours preoperatively
- Food, sweets and milky drinks up to 6 hours preoperatively
- No chewing gum on day of surgery
Starvation guidelines - children?
- Clear fluids
- Breast milk
- Food/cow’s milk/formula
Children
- Clear fluids and water up to 2 hours preoperatively
- Breast milk up to 4 hours preoperatively
- Formula/cow’s milk up to 6 hours preoperatively
- Food and sweets up to 6 hours preoperatively
Why should chewing gum be avoided pre-op?
There is evidence that chewing gum before surgery significantly increases gastric fluid volume, particularly in children.
