Is urgent intubation and/or ventilation required?

Assess if there is severe upper airway obstruction (see Chapter 59: Upper airway obstruction), inability to protect airway due to decreased consciousness (see Chapter 112: Airway management), impending respiratory or cardiac arrest, severe hypoxia despite oxygen treatment or severe acidosis/hypercapnia.

Prevent life-threatening hypoxia

Oxygen therapy is key in preventing life-threatening hypoxia, but caution should be taken. Patients known to suffer from COPD may have chronic respiratory failure with hypercapnia; in these patients hypoxia acts as a stimulus to ventilatory drive and abolishing it completely may make respiratory failure worse. These patients need controlled oxygen therapy. Thus, try to establish early, with the means of an arterial blood gas (see Chapter 118), whether the patient has type 1 or type 2 respiratory failure and instigate appropriate oxygen therapy (Figure 11.2).

Prevent life-threatening hypercapnia

Patients in type 2 respiratory failure will require controlled oxygen therapy via a Venturi mask, aiming for SaO₂ of 88–92% (Figure 11.2). Monitoring with repeat ABGs is important. If high PaCO₂ or acidosis persists, assisted ventilation will be required.

Diagnose and manage the underlying cause (Tables11.1, 11.2and11.3)

Careful history and examination (see Table 11.2) and appropriate investigations (see Table 11.3) are paramount. Management will largely be determined by the working diagnosis as well as the response to the initial treatment. Some treatments need to be instigated quickly. For example:

• Inhaled bronchodilator therapy (e.g. salbutamol 2.5–5 mg) and steroids (e.g. prednisolone 30–40 mg) in acute exacerbation of asthma or COPD (see Chapter 61).
• Intravenous diuretic (e.g. furosemide 40–80 mg) in acute pulmonary oedema (see Chapter 47).
• Antibiotic therapy in pneumonia (see Chapters 62 and 63).
• Anticoagulation (e.g. low-molecular-weight heparin) in pulmonary embolism (see Chapter 57).
• Chest physiotherapy in the presence of copious respiratory secretions which impair adequate gas exchange.
• Drainage of a large pleural effusion or pneumothorax (see Chapters 12 and 64).
• Non-invasive ventilation in acidotic hypercapnic respiratory failure in acute exacerbation of COPD that fails to respond to initial treatment and controlled oxygen therapy (see Table 11.4 and Chapters 61 and 113).
• Reversal of the effects of narcotic drugs (e.g. naloxone in opiate overdose, flumazenil in benzodiazepine overdose) (see Chapter 36).

Institute assisted ventilation if indicated (Tables11.4and11.5)

If, following treatment of the underlying problem, oxygen requirements remain high (e.g. >60%) or there is persistent acidosis with hypercapnia, assisted ventilation (invasive or non-invasive) should be considered, if appropriate given the clinical situation. See Tables 11.4 and 11.5, and Chapter 113.