Further terminology includes 'inflating valve', which is a device that enables lung inflation during IPPV, defined in a later International Organization for Standardization (ISO) publication specifically for draw-over systems (4).
This definition excludes such devices as the Manley Minute Volume Divider, the East Freeman and Flomasta (5) ventilators, which might otherwise be considered patient inflating devices with valves; it also excludes a paediatric non-return valve described by Zuck (6), which does not allow spontaneous breathing, and a similar arrangement for paediatric anaesthesia with a reservoir bag described by Lee (7), which has a one-way 'inhalation valve' but delivers IPPV by occluding a compressible exhaust tube without a valve.
The Laerdal valve (Figure 2) uses a different system, namely a duckbill type one-way valve made of silicone that opens during inspiration and also impinges upon a flat silicone ring that moves to close the exit port during IPPV.
The valve leaflets do not seat as well as in the adult model and when used on patients <5-7 kg the valve resistance means that sustained IPPV is needed in order to keep the patient adequately oxygenated and anaesthetised.
The hazard usually occurs when IPPV is applied to an apnoeic patient after giving a neuromuscular blocking drug.
Judge McKelvie's post trial rulings invalidated the only non-expired IPPV patent which had been found to be infringed.
With respect to the most important patent, for which IPPV sought approximately $80 million in damages, Judge McKelvie granted EchoStar's motion for summary judgment of non-infringement on the eve of trial.