Page 201 - 2023 SMOG Digital

VENTILATOR Terms

Volume-targeted modes: (Examples: CMV Continuous Mandatory Ventilation, A/C Assist/Control, SIMV Synchronized Intermittent
Mechanical Ventilation) - Volume constant, inspiration terminates when preset Vt delivered. Peak airway pressure is variable and
increases as needed to deliver prescribed Vt.
Pressure-targeted modes: (Examples: PSV Pressure Support Ventilation, PCV Pressure Controlled ventilation) - Volume variable,
terminates when preset pressure reached. Volume is variable. Peak airway pressure is fixed, determined by set pressure level.
Adaptive Support Ventilation (ASV): Only available on the Hamilton T1. ASV provides intelligent ventilation mode that continuously
adjusts respiratory rate, tidal volume, and inspiratory time depending on the patient’s lung mechanics and effort.
Tidal volume (Vt): The volume of gas, either inhaled or exhaled, during a breath and commonly expressed in milliliters. Vt is generally
set between 4-8ml/kg IBW (ideal body weight), to prevent lung over-distension and barotrauma.
Minute Ventilation (VE): The average volume of gas entering, or leaving, the lungs per minute, commonly expressed in liters per
minute. The product of Vt and RR (respiratory rate). Normal VE is 5–10L/min.
Inspiratory (I) and Expiratory (E) time and I:E ratio: The speed at which the Vt is delivered. Setting a shorter inspiratory time (I)
results in a faster inspiratory flow rate. Average adult I time is 0.7-1 second. I:E ratio is usually 1:2-1:4
Positive end-expiratory pressure (PEEP): The amount of positive pressure that is maintained at end-expiration. It is expressed in
centimeters of water. The purpose of PEEP is to increase end-expiratory lung volume and reduce air-space closure at end-expiration.
Normal Physiologic PEEP is 5cm/H2O.
Peak flow rate or peak inspiratory flow: The highest flow, or speed, that is set to deliver the Vt during inspiration, usually measured
in liters per minute. When the flow rate is set higher, the speed of gas delivery is faster and inspiratory time is shorter.
Peak Airway Pressure (PAW): 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: Effort, or negative pressure, required by the patient to trigger a machine breath, commonly set so
that minimal effort (-1 to -2 cm H2O) is required to trigger a breath.

201