Prehospital Mechanical Ventilation: An NAEMSP Position Statement and Resource Document

Figures & data

Table 1. Benefits of mechanical transport ventilation methods.

Provide the intubated patient with consistency in ventilation parameters including respiratory rate and tidal volume. Maximizing ventilation, improving oxygenation and the elimination of carbon dioxide. Limiting airway pressures and potential complications including barotrauma, gastric distention, and hypotension. Allow the transport team to focus on other aspects of patient care.

Table 2. General concepts of mechanical ventilation and key terminology.

Positive End Expiratory Pressure (PEEP)
Positive pressure applied during the expiratory phase following delivery of a mandatory or spontaneous breath.
Respiratory Frequency
Breathing cycles or breaths per minute delivered by the ventilator.
Tidal Volume (Vt)
Volume inspired or expired during a normal breath.
Control Variable
Which variable the ventilator will control. Ventilators normally control either tidal volume or peak pressure.
Fraction of Inspired Oxygen (FiO2)
Fraction oxygen delivered to the patient. Set between 21% (room air) to 100%; usually adjusted to maintain PaO2 level greater than 60 mmHg or SaO2 level greater than 90%.
Auto-PEEP
Intrinsic PEEP occurs when a positive-pressure breath is delivered before complete exhalation of the previous breath, air becomes trapped and pressure within the lungs becomes trapped, potentially leading to decreased cardiac output, hypotension and even pneumothorax.
Expiratory Time (Te)
The time from the start of expiratory flow to the start of inspiratory flow.
I:E Ratio
Ratio of inspiratory time to expiratory time. Normal I:E ratio is 1:3. During mechanical ventilation I:E should be 1:2 or greater to prevent air trapping.
Inspiratory Flow (Vi)
Glow of gas measured at the airway opening during inspiration. Normal inspiratory flow during mechanical ventilation is 60–100 L/minute.
Inspiratory Time (Ti)
Time from the beginning of inspiratory flow until the beginning of expiratory flow.
Peak Inspiratory Pressure (PIP)
Highest proximal airway pressure produced in the patient circuit during the inspiratory phase. The stiffer the lungs, the greater the PIP.