Four major parameters: tidal volume, pressure, flow, time (including breathing frequency, breath-in ratio).
1. Tidal volume: The tidal output must be greater than the physiological tidal volume of the person, the physiological tidal volume is 6-10 ml / kg, and the tidal output of the ventilator can reach 10-15 ml / kg, which is often the physiological tidal volume 1 ~ 2 times. It should be further adjusted according to chest fluctuations, auscultation of the air intake of both lungs, reference pressure table, blood gas analysis.
2. Breathing frequency: close to physiological breathing frequency. 40-50 times / min for newborns, 30-40 times / min for infants, 20-30 times / min for older children, 16-20 times / min for adults. Tidal volume * Breathing frequency = minute ventilation.
3. Inspiratory-expiratory ratio: generally 1: 1.5-2, obstructive ventilation disorder can be adjusted to 1: 3 or longer exhalation time, restrictive ventilation disorder can be adjusted to 1: 1.
4. Pressure: generally refers to the peak airway pressure (PIP). When the lung compliance is normal, the peak inspiratory pressure is generally 10-20 cm water column, the lung lesions are mild: 20-25 cm water column; moderate: 25 -30 mm water column; Severity: 30 cm water column or more, RDS, pulmonary hemorrhage can reach 60 cm water column or more. But generally below 30, the newborn is 5 cm lower than the above pressure water column.
5. PEEP patients who use IPPV generally give PEEP a 2-3 cm water column that meets physiological conditions. When severe ventilation disorders (RDS, pulmonary edema, pulmonary hemorrhage) need to increase PEEP, generally 4-10 cm water column, the condition is serious Those can reach 15 or more than 20 cm water column. When the oxygen concentration exceeds 60% (FiO2 is greater than 0.6), if the arterial blood oxygen partial pressure is still below 80 mm Hg, the increase in PEEP should be the main factor until the arterial blood oxygen partial pressure exceeds 80 mm Hg. Each increase or decrease of 1 to 2 mm of water column in PEEP will have a great impact on blood oxygen. This effect will appear within a few minutes. The reduction of PEEP should be done gradually, and pay attention to monitoring changes in blood oxygen. The PEEP value can be read from the position of the pressure gauge pointer at the end of expiration. (There is a special display better)
6. Flow rate: at least twice the ventilation rate per minute, generally 4-10 liters / min.