Mechanical Ventilation Awareness

Mechanical ventilation assists oxygenation, carbon dioxide removal, or both when a patient cannot maintain adequate gas exchange independently. Non-invasive positive-pressure ventilation delivers support through a mask. Invasive ventilation delivers positive-pressure breaths through an endotracheal tube or tracheostomy. Positive pressure changes the pressure gradient that moves gas into the lungs. It can recruit collapsed alveoli and reduce the work of breathing, but it does not remove the cause of respiratory failure. Pneumonia, pulmonary oedema, bronchospasm, sedation, neuromuscular weakness, and shock still require assessment and treatment. The ventilator’s most relevant variables are: - FiO₂: the oxygen concentration delivered. - PEEP: pressure maintained at the end of exhalation to limit alveolar collapse. - Tidal volume: the amount delivered with each breath. - Respiratory rate: the number of mandatory breaths delivered each minute. PEEP can improve oxygenation by keeping recruitable alveoli open. Excessive intrathoracic pressure, however, can reduce venous return and worsen hypotension. The correct setting is therefore judged by the patient’s oxygenation, ventilation, blood pressure, lung mechanics, and work of breathing—not by a single number. Assist-control gives a full preset breath whenever the...