In adults when 100% FiO2 is used initially, it is easy to calculate the next FiO2 to be used and easy to estimate the shunt fraction. When using 100% FiO2, the degree of shunting is estimated by subtracting the measured PaO2 (from an arterial blood gas) from 700 mmHg. For each difference of 100 mmHg, the shunt is 5%. A shunt of more than 25% should prompt a search for the cause of this hypoxemia, such as mainstem intubation or pneumothorax, and should be treated accordingly. Patients should have their ventilation considered for withdrawal if they are able to support their own ventilation and oxygenation, and this should be assessed continuously. Specific clinical, ventilator and oxygenation criteria should be met in order to do a trial of spontaneous breathing in mechanically ventilated patients.
Mechanical ventilation modification of settings
Mechanical ventilation initial ventilator settings
Medical ventilator
Artificial respiration
Respiratory failure mechanical ventilation
Mechanical ventilation choosing amongst ventilator modes
Acute respiratory distress syndrome mechanical ventilation therapy
Mechanical ventilation protocol