VENTILATOR ADJUSTABLE SETTINGS

Tidal volume (VT )

The volume of gas, exchanged during a breath and commonly expressed in milliliters. VT is generally set between 4-8ml/kg IBW, to prevent lung over distension and barotrauma.4-8

Ideal IBW

The weight at which tidal volume is calculated against instead of using actual weight. This enables patients to be ventilated in a lung-protective strategy. A quick reference chart can be found in Appendix C. IBW can be calculated manually as follows:

- Male: {(Height in inches-60) x 2.2} +50 (e.g. 72in-60= 12; 12 x 2.2 = 26.4; 26.4 + 50 = IBW of 76.4 kg)
- Female: {(Height in inches-60) x 2.2} +45 (e.g. 65in-60= 5; 5 x 2.2 = 11; 11 + 45 = IBW of 56 kg)

Minute Ventilation (VE)

The average volume of gas entering, or leaving, the lungs per minute, commonly expressed in liters per minute. Also called minute volume. Minute ventilation is the product of VT and RR (respiratory rate). Normal VE is 5 – 10 L/min. 4-8

I:E Ratio

See I:E definition. I:E might need to be adjusted for physiology that requires extended exhalation time. 4-8 For example: Asthma patient may require an I:E of 1:3, 1:4, or 1:5 to allow for more exhalation time.

Flow Rate

Is the velocity at which gas is delivered to the patient, expressed in liters per minute. When the flow rate is set higher, the speed of gas delivery is faster and inspiratory time is shorter. 4-8

Peak Inspiratory Pressure (PIP)

Represents the total pressure that is required to deliver the VT and depends upon various airway resistance, lung compliance, and chest wall factors. It is expressed in centimeters of water (cm H2O).

Sensitivity or trigger sensitivity

Trigger sensitivity Is the effort, or negative pressure, required by the patient to trigger a machine breath, commonly set so that minimal effort (-1 to -2 cm H2O) triggers a breath.1,3 This is usually seen with assist modes of ventilator operation.

Pressure alarms

Pressure alarms ensure that providers are alerted to pressures that fall outside of appropriate ranges and have potential to harm the patient via barotrauma (over-pressure) or under-ventilation (circuit disconnect or under-pressure). Pressures will be determined by placing the patient on the vent for ~1-2 minutes and determining intrinsic peak inspiratory pressure. (Labeled as PEAK on 754 Ventilator (top right); Labeled as peak on Hamilton T1 ventilator (top left); Labeled as PIP on ZOLL EMV+ (731) (right center). Standard alarm settings should be: Need to measure a peak pressure 5 min after setting initial settings.

- High pressure alarm: 10 cmH2O above peak airway pressure.
- Low pressure alarm: 5 cmH2O below peak airway pressure.