ABSTRACT
Respiratory failure is defined as the inability to maintain the partial pressures in arterial blood of carbon dioxide (PaCO2) and oxygen (PaO2) within normal physiological limits.
Key physiological principles Respiratory failure may occur as a result of: • Failure of gas exchange due to lung disease (‘Type l’ or ‘hypoxemic’ failure). • Failure of the respiratory pump: chest wall, respiratory muscles, and/or central/peripheral
neural components (‘Type 2’ or ‘ventilatory’ failure). • Failure of either the gas exchange or respiratory pump component produces distinct
pathophysiological features (c.f. impaired gaseous exchange, respiratory muscle dysfunction). However the two are frequently interlinked, and the presence of one invariably leads to the development or exacerbation of the other.
