Pressure Regulated Volume Control
Encyclopedia
Pressure regulated volume control (PRVC) is a mode of mechanical ventilation
with a VT set as a goal amount. Pressure varies with a peak pressure limit included to reduce lung trauma and use only the minimum pressure required to deliver the goal tidal volume (VT). Pressure regulated volume control is a mode of mechanical ventilation where the breaths are delivered mandatorily to assure preset volumes, with a constant inspiratory pressure continuously adapting to the patient
's condition. The flow pattern is decelerating. This mode is a form of intermittent mandatory ventilation, the breaths can either be ventilator initiated or patient initiated. This mode combines the advantages of volume controlled and pressure control
led ventilation.
The first breath delivered to the patient is a volume controlled breath. The measured plateau pressure is used as the pressure level for the next breath. The pressure is constant during the set inspiratory time and the flow is decelerating. The set tidal volume
is achieved by automatic, breath-by-breath pressure regulation. The ventilator will adjust the inspiratory pressure control level, according to the mechanical properties of the airway
s/lung
/thorax, to the lowest possible level to guarantee the preset tidal volume. If the measured tidal volume increases above the preset, the pressure level decreases in steps of maximum 3 cmH2O (300 Pa
) between consecutive breaths until the preset tidal volume is delivered. Maximum available pressure level is 5 cmH2O (500 Pa) below a preset upper pressure limit.
Modes of mechanical ventilation
Modes of mechanical ventilation are one of the most important aspects of the usage of mechanical ventilation. The mode refers to the method of inspiratory support. Mode selection is generally based on clinician familiarity and institutional preferences since there is a paucity of evidence...
with a VT set as a goal amount. Pressure varies with a peak pressure limit included to reduce lung trauma and use only the minimum pressure required to deliver the goal tidal volume (VT). Pressure regulated volume control is a mode of mechanical ventilation where the breaths are delivered mandatorily to assure preset volumes, with a constant inspiratory pressure continuously adapting to the patient
Patient
A patient is any recipient of healthcare services. The patient is most often ill or injured and in need of treatment by a physician, advanced practice registered nurse, veterinarian, or other health care provider....
's condition. The flow pattern is decelerating. This mode is a form of intermittent mandatory ventilation, the breaths can either be ventilator initiated or patient initiated. This mode combines the advantages of volume controlled and pressure control
Pressure control
Pressure control is a mode of mechanical ventilation alone and a variable within other modes of mechanical ventilation. Pressure control is used to regulate pressures applied during mechanical ventilation. Air delivered into the patients lungs are currently regulated by Volume Control or...
led ventilation.
The first breath delivered to the patient is a volume controlled breath. The measured plateau pressure is used as the pressure level for the next breath. The pressure is constant during the set inspiratory time and the flow is decelerating. The set tidal volume
Tidal volume
Tidal volume is the lung volume representing the normal volume of air displaced between normal inspiration and expiration when extra effort is not applied.Typical values are around 500ml or 7ml/kg bodyweight.-Mechanical Ventilation:...
is achieved by automatic, breath-by-breath pressure regulation. The ventilator will adjust the inspiratory pressure control level, according to the mechanical properties of the airway
Airway
The pulmonary airway comprises those parts of the respiratory system through which air flows, conceptually beginning at the nose and mouth, and terminating in the alveoli...
s/lung
Human lung
The human lungs are the organs of respiration in humans. Humans have two lungs, with the left being divided into two lobes and the right into three lobes. Together, the lungs contain approximately of airways and 300 to 500 million alveoli, having a total surface area of about in...
/thorax, to the lowest possible level to guarantee the preset tidal volume. If the measured tidal volume increases above the preset, the pressure level decreases in steps of maximum 3 cmH2O (300 Pa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
) between consecutive breaths until the preset tidal volume is delivered. Maximum available pressure level is 5 cmH2O (500 Pa) below a preset upper pressure limit.
Advantages
- Maintains a minimum positive pressure(PIP)
- Guaranteed tidal volume (VT)
- Patient has very little work of breathing (WOB) requirement.
- Allows patient control of respiratory rate Decelerating flow waveform for improved gas distribution
- Breath by breath analysis
Disadvantages
- Varying mean airway pressure
- May cause or worsen autoPEEP
- When patient demand is increased, pressure level may diminish when support is needed
- May be tolerated poorly in awake non-sedated patients
- A sudden increase in respiratory rate and demand may result in a decrease in ventilator support