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FIGURE 26 IPPV
• PCV
In PCV (Pressure Controlled Ventilation), airway pressure and inspiration
duration are preset. After inspiration is started, air flow rate is raised quickly
to the preset pressure level and then slowed down by the feedback system
and maintained at the preset pressure till end of inspiration, and then
expiration is started. Each ventilation is of full load based on preset pressure.
In PCV, airway pressure falls, and there is no peak pressure, and rare
barotrauma, which is beneficial for aeration of pulmonary alveolus,
improvement to ventilation-blood stream rate and optimization of air
exchange. PCV is primarily used for newborn, infants and patients suffering
respiratory insufficiency, severe unbalancing ventilation-blood stream rate
resulted from ARDS or COPD, ensures supply of tidal volume even in case of
leakage of respiratory hose.
A typical pressure waveform of PCV is shown below：
FIGURE 27 PCV
5.5.2 V-A/C and P-A/C
• CV
In CV (Controlled Ventilation), which is also known as Mandatory Ventilation,
respirator provides ventilation at preset frequency, in preset tidal volume or
at preset pressure, periodically activates inspiration and switches to
expiration, completely in place of patient's independent breathing. The
patient's breathing modes (frequency, tidal volume, expiration time and
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