Ventilator Monitoring parameters – Basic

Date: November 29, 2023 | Posted by: Vikram Aditya Tirthani

Understanding the intricate web of ventilator monitoring parameters is crucial for healthcare professionals to deliver precise and tailored respiratory care. Let’s embark on a journey of decoding these parameters, shedding light on their significance and the insights they provide.

 Tidal Volume (Vt)

Tidal volume represents the amount of air delivered with each breath. It is a fundamental parameter as it directly influences the exchange of oxygen and carbon dioxide in the lungs. Monitoring tidal volume ensures that patients receive an appropriate amount of ventilation to maintain optimal oxygenation.

 TVe : (Expiratory Tidal Volume)

TVe measures the volume of air exhaled during expiration by the patient. It is determined from the flow sensor measurement, so it does not show any volume added due to compression or lost due to leaks in the breathing circuit. If there is a leak on the patient’s side, the displayed TVe may be less than the tidal volume the patient actually receives.

 TVi : (Inspiratory Tidal Volume)

TVi is the tidal volume of air inhaled during inspiration by the patient, determined from the flow sensor measurement. If there is a gas leak on the patient’s side, the displayed TVi may be larger than the displayed TVe.

TVe spn : (Spontaneous Expiratory Tidal Volume)

TVe measures the volume of air exhaled during expiration by the patient during spontaneous breathing. It is determined from the flow sensor measurement.

Respiratory Rate (RR)

Respiratory rate signifies the number of breaths delivered per minute. This parameter is closely tied to the patient’s physiological needs and helps healthcare providers adjust ventilator settings to match the individual’s respiratory demand.

MVe : (Expiratory Minute Volume total)

MVe is the accumulated tidal volume of air exhaled in one minute. It is measured by the moving average over the last 8 breaths of the monitored exhaled volume per minute.

MVspn : (Spontaneous Expiratory Minute Volume)

MVspn measures the minute volume of spontaneous exhalation. It is monitored by the moving average method for the last 8 values of expired tidal volume per minute.

MVi : (Inspiratory Minute Volume)

MVi is the minute volume of inspiration. It is measured by the moving average over the last 8 breaths of the monitored Inspiratory Tidal volume per minute.

Peak Inspiratory Pressure (PIP)

PIP measures the highest pressure reached during inspiration. Monitoring PIP is crucial to prevent lung injury and barotrauma. Elevated PIP may indicate increased airway resistance or decreased lung compliance.

Positive End-Expiratory Pressure (PEEP)

PEEP is the pressure maintained in the airways at the end of expiration. It prevents alveolar collapse and improves oxygenation. Adjusting PEEP levels is vital in managing conditions like acute respiratory distress syndrome (ARDS).

Fraction of Inspired Oxygen (FiO2)

FiO2 represents the percentage of oxygen delivered to the patient. Monitoring FiO2 ensures that patients receive the appropriate concentration of oxygen to maintain optimal blood oxygen levels without the risk of oxygen toxicity.

Inspiratory Time (Ti) and Expiratory Time (Te)

Inspiratory time is the duration of the breath, while expiratory time is the duration of exhalation. Balancing Ti and Te is crucial to optimize ventilation and prevent complications such as auto-PEEP (dynamic hyperinflation).

Compliance and Resistance

Monitoring lung compliance and airway resistance provides insights into the condition of the patient’s respiratory system. Changes in these parameters may indicate lung pathology or other complications.

 Ppeak (Peak Pressure)

Ppeak is the highest airway pressure during inspiration, representing the maximum pressure in the respiratory cycle.

Airway Pressure (Paw)

Paw refers to airway pressure during the respiratory cycle. It encompasses Ppeak, Pplat, Pmean, and PEEP. It is a calculated value showing the ratio of tidal volume to static compliance, which reflects the difference between Pplateau and PEEP.

 Pplat – (Plateau Pressure)

Pplat is the measured value of pressure at the end of the inspiratory cycle during mandatory breaths, it is measured by keeping the flow value zero while closing the expiratory valve. It’s useful for assessing alveolar pressure and lung compliance.

Pmean – (Mean Pressure)

Pmean represents the average airway pressure throughout the respiratory cycle. Pmean is an important indicator of the possible impact of applied positive pressure on hemodynamics and surrounding organs.

PEEP – (Positive End-Expiratory Pressure)

PEEP is the monitored value of positive pressure in the airways at the end of the expiration cycle. This monitored value may differ slightly from the set value, especially with patients with spontaneous breaths.


P0.1 represents the Patient’s respiratory drive and the patient’s inspiratory efforts. It is airway occlusion pressure, and the pressure drops during the first 100 ms when a breath is triggered when the patient starts spontaneous breathing, In other words, it represents the pressure at the 0.1-second point during inspiration.

PTP (Inspiratory pressure time product)

The measured pressure drop required to trigger the breath is multiplied by the time interval until the PEEP level is reached at the beginning of inspiration. PTP is valid for patient-initiated breaths only and indicates work by the patient to trigger the breath.

 Leak : (Percentage of leakage)

Leak calculates the percentage of unintentional leakage. By calculating the difference between the inspiratory and expiratory volume.

 MVleak : (Minute Volume Leakage)

MVleak represents the minute volume of unintentional leakage. The accumulated leakage (inspiratory volume minus expiratory volume) in one minute.

 TVe/IBW – (Tidal volume expiratory per kg)

TVe/IBW calculates the delivered tidal volume per kilogram of ideal body weight.

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