Respiratory and Critical Care Emergencies
What the board tests
Severity stratification and escalation in asthma and COPD, rapid rule-out of pulmonary embolism, sepsis resuscitation, and safe initiation of non-invasive and invasive ventilation.
Obstructive disease
- Severe asthma: inability to speak, silent chest, exhaustion, SpO2 under 92%, peak flow under 33% predicted, and a normal or rising PaCO2 are danger signs.
- Treat with oxygen to SpO2 94-98%, repeated or continuous salbutamol, ipratropium, early systemic corticosteroid, and IV magnesium sulphate 2 g over 20 min in severe cases.
- COPD with pH 7.25-7.35 and PaCO2 above 45 mmHg is the classic NIV indication; contraindications include vomiting, unprotected airway, agitation and pneumothorax.
PE, pneumonia and sepsis
- PE: use Wells or the PERC rule to decide on D-dimer (age-adjusted) versus CT pulmonary angiography; a haemodynamically unstable patient with suspected PE gets thrombolysis or catheter-directed therapy, not a CT first.
- Pneumonia: CURB-65 for site of care, antibiotics within 4 h, early steroids in severe community-acquired pneumonia.
- Sepsis: cultures, lactate, 30 mL/kg crystalloid for hypotension or lactate 4 mmol/L or more, then noradrenaline to MAP 65 mmHg.
Ventilation essentials
Lung-protective ventilation: tidal volume 6 mL/kg predicted body weight, plateau pressure under 30 cmH2O, adequate PEEP, permissive hypercapnia. Prone position for P/F ratio under 150. Sedate and provide analgesia before paralysis; avoid stacking breaths in the asthmatic by accepting a higher PaCO2 and lower respiratory rate.
Worked example
A 28-year-old asthmatic is drowsy with a silent chest, SpO2 88% and PaCO2 58 mmHg after three nebulisers. This is life-threatening asthma with impending respiratory arrest: call for senior and anaesthetic help, give continuous salbutamol with ipratropium, IV magnesium, IV hydrocortisone, and prepare for intubation with ketamine and a low respiratory rate strategy; avoid non-invasive ventilation in the drowsy patient.
Traps
Treating a normal PaCO2 in acute asthma as reassuring; routine NIV in asthma or in the vomiting patient; large tidal volumes in ARDS; fluid-loading cardiogenic pulmonary oedema; withholding steroids until admission.