Respiratory failure, ARDS. Modes of mechanical ventilation

1. Big picture

Respiratory failure means the respiratory system cannot maintain adequate gas exchange. In the exam, think in two questions:

1. Is the patient oxygenating? Low arterial oxygen pressure = hypoxemic respiratory failure.

2. Is the patient ventilating? High arterial carbon dioxide pressure = hypercapnic respiratory failure.

The dangerous clinical pattern is:

Dyspnea + tachypnea + low SpO₂ or abnormal arterial blood gas → assess airway, breathing, circulation → oxygen/ventilation support → identify cause → treat cause.

Acute respiratory distress syndrome, ARDS, is a severe inflammatory form of acute hypoxemic respiratory failure caused by diffuse alveolar-capillary injury, non-cardiogenic pulmonary edema, stiff lungs, and refractory hypoxemia.

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