SimCase 002

• Start at 5

• Default is 50 – Aim for SpO₂ 86-92%

• Start at 10 and ensure TV>6ml/kg (>410ml).
• If after 15 min RR is >25, increase to TV >8ml/kg (>547ml)
• If after another 15 min RR is >25, increase to TV >10ml/kg (>685ml)
• Check gas in an hour

CXR: COPD

VBG:

• pH 7.18 (low): Significant acidaemia.
• pCO₂ 95 mmHg (very high): Severe respiratory acidosis (marked CO₂ retention).
• HCO₃⁻ 34 mmol/L (high) + Base excess +6: Renal metabolic compensation is present.
• Hb 175 g/L (high): Suggests secondary polycythaemia, consistent with chronic hypoxia.
• Interpretation: Acute on chronic respiratory acidosis (e.g. COPD exacerbation) with severe CO₂ retention with partial metabolic compensation.

Acute on chronic respiratory acidosis – severe acidaemia = tiring

VAPOX: Ventilator-assisted preoxygenation

• PEEP = 5
• FiO₂ = 100%
• Rate = 6 so that it’s obvious when Ketamine kicks in
• Ketamine 0.5 mg/kg IBW; so likely 50mg over 90s

• RR = 10
• Titrate later depending on gases ensuring that no gas trapping on flow curve

• Leave PEEP at 5
• Titrate SpO₂ to 86-92%

• Press Alarms
• Increase upper limit of Pressure (max 70) while trouble shooting to allow TV
• If still going off, touch Graphics then Dynamic lung – make diagnosis of OBSTRUCTIVE lung disease

Note: if we didn’t change, gas trapping would get to the point that we would be have MIXED LUNG DISEASE (box on right; high resistance and high compliance) which would manifest itself as dropping BP and we would need to disconnect patient & manually decompress chest.

As it is we need to decrease the rate – use the flow curve to show them how to get to the optimal rate. Ensure your I:E is >1:4

Now that the patient is stablised…switch to ASV so they see what it does

• 90% MinVol
• PEEP 5
• FiO₂ titrate to SpO₂ to 86-92%
• Gives RR 9 and TV 682mL

Use the card to show how the ‘safety window’ can be used diagnostically

• Tall rectangle = obstructive lung
• Long rectangle = restrictive lung

The small square of the mixed lung disease is the T1 threading the small needle of a COPD with pneumonia, balancing the degree of obstruction/restriction

The T1 uses significantly larger volumes than our manual strategy but that’s because our manual strategy of 6ml/kg is an oversimplification. You want your plan B to be different from your plan A

SimMon: Show shark-fin ETCO₂ waveform.

T1: Demonstrate flow curves not returning to baseline (gas trapping).

Trigger high pressure/low Vt alarms → guide learners to:

• Press Alarms, temporarily increase pressure limit (max 70).
• Use Graphics → Dynamic Lung → identify obstructive pattern.

Make the point: if untreated, gas trapping → mixed lung disease with hypotension → disconnect and decompress chest.

Once stable, switch to ASV:

• %MinVol: 90%
• PEEP: 5
• FiO₂: titrate to SpO₂ 86–92%
• Learners should observe T1 chooses larger Vt and lower RR than their manual settings.