Controlled ventilation (intermittent positive pressure ventilation – IPPV), uses positive pressure at the mouth to create a pressure gradient during inspiration.

A higher pressure is normally needed (~ 10-15 cm H₂O) to deliver the same tidal volume during IPPV.

Again, the elastic energy stored in the lungs and chest wall provides the drive for expiration.

Question: What unwanted effect does IPPV have on the circulation?

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Controlled ventilation (intermittent positive pressure ventilation – IPPV), uses positive pressure at the mouth to create a pressure gradient during inspiration.

A higher pressure is normally needed (~ 10-15 cm H₂O) to deliver the same tidal volume during IPPV.

Again, the elastic energy stored in the lungs and chest wall provides the drive for expiration.

Question: What unwanted effect does IPPV have on the circulation?

Answer: The increase in mean intrathoracic pressure reduces venous return to the heart, leading to a fall in cardiac output – it is a similar effect to the Valsalva Manoeuvre.