ILA 7: Resp disease & anaesthesia

Question 1

Mr. Jones is a 60 year old retired cab driver who has come in for a revision knee replacement. He is seen regularly in chest clinic with COPD. His BMI is 31.5.

• How will you assess Mr Jones respiratory status?

Answer 1

History:

• Acute symptoms: current infection, SOB, reduced exercise tolerance, etc.
• Long-term disease control: medications, admissions (esp. HDU/ITU), oral steroid courses, HMV/LTOT

Examination:

• Observations
• Resp exam (paraphernalia, clubbing, hypoxia, accessory muscles, talk fluently, focal signs)

Tests:

• FEV1 (<0.3 = very severe, 0.3-0.5 = severe, 0.5-0.8 = moderate, >0.8 = mild)
• FEV1/FVC ratio (<0.7 = COPD)
• Blood gas (well-compensated?)
• Possible CXR if focal signs suspected

Question 2

Pathophysiology of COPD

Answer 2

Inflammation of the airways, causing thickening of the epithelium and mucus production, resulting in airways obstruction (irreversible).
Leads to air-trapping and emphysema.

Question 3

COPD: management

Answer 3

• Conservative
• Medications: SABA, LABA, ICS, etc.
• Ventilation/LTOT

Question 4

Breathlessness: MRC classification

note: NYHA is used for cardiac disease

Answer 4

1 - not troubled by SOB except on strenuous exercise
2 - SOB when hurrying on level ground or walking up slight hill
3 - walks slower than normal people or stops after 15 mins walking at own pace
4 - stop after a few hundred yards/few mins on the flat
5 - too breathless to leave house/breathless on undressing

Question 5

How can cardiorespiratory function be measured?

Answer 5

CPET

Question 6

How can functional status be measured?

Answer 6

METS

Question 7

How can you prepare this COPD man for surgery?

Answer 7

• Stop smoking ideally 6-8 weeks pre-surgery (and at least 12 hours before)
• Optimise medications to alleviate symptoms
• Weight loss
• Physiotherapy - increase exercise tolerance

Question 8

Mr Jones’ wife comments in pre-assessment clinic that he snores loudly. What relevance might this have? What further questions would you like to ask Mr Jones and his wife? How may you take this further?

Answer 8

• May indicate airway obstruction
• Upon extubation, airway may obstruct due to anaesthetic effects
• Opiates may worsen this

Question 9

OSA: risk factors
Mnemonic - STOP BANG
(0-2: low risk of OSA, 3-4: moderate, 5-8: high risk)

Answer 9

Snoring
Tiredness during the day
Observed apnoea
Pressure (hypertension)
BMI >35
Age >50
Neck circumference >40cm
Gender (male)

Question 10

OSA: operative management

Answer 10

Pre-op: blood gas, book HDU bed post-op
Op: avoid GA and sedation if possible, if need GA then use ETT.
Post-op: extubate carefully, HDU

Question 11

Why spinal may be preferable to GA

Answer 11

• You shouldn’t put someone under GA (if can be avoided) where they are at risk of difficult extubation
• Less post-op issues: when spinal wears off, they will probably be okay to go home
• Analgesia
• BP lower: less blood loss
• Improved venous circulation: lower VTE risk

Question 12

Oral steroids can cause adrenal suppression and subsequent inadequate response during stress, such as the peri-operative period.
What should you do about this?

Answer 12

Convert oral steroids (pred) to IV hydrocortisone. Conversion ratio = 1:4 (10mg pred = 40mg hydrocortisone)

Question 13

Thromboprophylaxis:

a) types
b) if need a spinal
c) with indwelling epidural

Answer 13

a) - Mechanical: stockings, pneumatic (Flotron boots)
- Medical: anticoagulation (LMWH)
b) Don’t do spinal within 12h of last dose of LMWH (to avoid epidural haematoma)
c) don’t take out for 12h after last dose