Common Parameter Ranges for Mechanical Ventilators

        A mechanical ventilator is an effective means of replacing a patient's spontaneous ventilation. It is widely used in clinical practice and has important clinical significance in respiratory failure, intraoperative anesthesia, emergency resuscitation, and other settings. Ventilator parameters include ventilation rate, tidal volume, inspiratory flow rate, inspiratory-to-expiratory ratio, flow pattern, fraction of inspired oxygen, and trigger sensitivity. Their normal value ranges are as follows:

        ◆ Ventilation rate: For adult patients, the respiratory rate is generally set at 15–20 breaths/min. The rate setting varies according to the patient's condition.

        ◆ Tidal volume: For adults, it is generally 5–15 mL/kg, with a commonly used range of 8–12 mL/kg. The specific tidal volume should be determined according to the patient's own condition, taking into account factors such as airway resistance, oxygenation status, and ventilation function, and comprehensively judging the tidal volume suitable for the patient.

 
        ◆ Inspiratory flow rate: The inspiratory flow rate is generally set at 40–100 L/min.

        ◆ Inspiratory-to-expiratory ratio: In general, the inspiratory-to-expiratory ratio is set at 1:2 to 1:1.5. This is because the setting of the inspiratory-to-expiratory ratio should comprehensively consider the effects of mechanical ventilation on the patient, including hemodynamics, oxygenation status, and other factors.

        ◆ Flow pattern: Common flow patterns include decelerating flow, accelerating flow, square-wave flow, and sine-wave flow. Different flow patterns are selected according to the patient's own condition.

        ◆ Fraction of inspired oxygen: The fraction of inspired oxygen should be determined according to factors such as the arterial partial pressure of oxygen and the patient's hemodynamic status. In general, the oxygen concentration is required to be less than 60%.

        ◆ Trigger sensitivity: Different ventilators have different trigger sensitivity settings, but the purpose of all of them is to monitor intra-alveolar pressure. For pressure triggering, the setting is generally -0.5 to -1.5 cmH2O; for flow triggering, the ventilator is set at 1–3 L/min.

        When using a ventilator, its function should be checked to ensure that it can work properly. At the same time, the patient's electrocardiographic monitoring should be closely monitored, and ventilator alarm values should be set so that changes in the patient's vital signs can be detected early.