Respiratory failure refers to the severe dysfunction in pulmonary ventilation and gas exchange in the respiratory system caused by various reasons under normal conditions. This dysfunction leads to ineffective gas exchange during respiration, resulting in hypoxia in the body and retention of carbon dioxide, thereby causing a series of physiological and metabolic disorders. Typically, under resting conditions at sea-level atmospheric pressure, respiratory failure is defined when arterial oxygen tension falls below 60 mmHg, accompanied by carbon dioxide retention, with carbon dioxide tension exceeding 50 mmHg, or without an increase in carbon dioxide tension. It is categorized into acute respiratory failure and chronic respiratory failure.