Mechanical Ventilation

T lecture offers an approach in which the ventilator is used as a probe of the patient’s respiratory system mechanical derangements, and then the ventilator settings are tailored to the patient’s mechanical and gas exchange abnormalities. This facilitates early stabilization of the patient on the ventilator in such a way as to optimize carbon dioxide removal and oxygen delivery within the limits of abnormal neuromuscular function, lung mechanics, and gas exchange. The fundamental purpose of mechanical ventilation is to assist in elimination of carbon dioxide and uptake of adequate oxygen while the patient is unable to do so or should not be allowed to do so. Such patients fall into two main groups: (1) those in whom full rest of the respiratory muscles is indicated (such as during shock; severe, acute pulmonary derangement; or deep sedation or anesthesia), and (2) those in whom some degree of respiratory muscle use is desired (eg, to strengthen or improve the coordination of the respiratory muscles; to assess the ability of the patient to sustain the work of breathing; or to begin spontaneous ventilation). It is important for the intensivist to be explicit about whether the respiratory muscles should be rested or exercised because the details of ventilation (mode, settings) usually follow logically from this fundamental point. Mechanical Ventilation