The ventilator is adjusted so that the patient is comfortable and breathes “in sync” with the machine. Minimal alteration of the normal cardiovascular and pulmonary dynamics is desired. Modes of mechanical ventilation are described in Figure 25-7. If the volume ventilator is adjusted appropriately, the patient’s ar-terial blood gas values will be satisfactory and there will be little or no cardiovascular compromise. Chart 25-12 discusses how to achieve adequate mechanical ventilation for each patient.
The ventilator needs to be assessed to make sure that it is func-tioning properly and that the settings are appropriate. Even though the nurse is not primarily responsible for adjusting the settings on the ventilator or measuring ventilator parameters (usually the responsibility of the respiratory therapist), the nurse is responsible for the patient and therefore needs to evaluate how the ventilator affects the patient’s overall status.
In monitoring the ventilator, the nurse should note the following:
· Type of ventilator (such as volume-cycled, pressure-cycled, negative-pressure)
· Controlling mode (such as controlled ventilation, assist–control ventilation, synchronized intermittent manda-tory ventilation)
· Tidal volume and rate settings (tidal volume is usually 10 to 15 mL/kg; rate is usually 12 to 16/min)
· FiO2 (fraction of inspired oxygen) setting
· Inspiratory pressure reached and pressure limit (normal is 15 to 20 cm H2O; this increases if there is increased airway resistance or decreased compliance)
· Sensitivity (a 2-cm H2O inspiratory force should trigger the ventilator)
· Inspiratory-to-expiratory ratio (usually 1 3 [1 second of in-spiration to 3 seconds of expiration] or 1 2)
· Minute volume (tidal volume × respiratory rate, usually 6 to 8 L/min)
· Sigh settings (usually 1.5 times the tidal volume and ranging from 1 to 3 per hour), if applicable
· Water in the tubing, disconnection or kinking of the tubing
· Humidification (humidifier filled with water) and temper-ature
· Alarms (turned on and functioning properly)
· PEEP and/or pressure support level, if applicable. PEEP is usually 5 to 15 cm H2O