Author(s): A.C. Lua & K.C. Shi
Proportional-assist ventilation (PAV) is an effective and improved mode of ventilation
over the conventional pressure-support ventilation due to its attractive features
of better patient harmony and comfort.
The conventional ventilation systems in
hospitals will either deliver a specified tidal volume to the patient or raise the airway
pressure to a preset level during the inspiratory phase of each breath.
systems do not take into consideration the patientís breathing patterns and varying
requirements during each inspiration.
To assist patients with breathing difficulties,
PAV has been used as a mode of synchronized partial ventilatory support,
by applying airway pressure in proportion to volume and flow rate to overcome
the patientís higher respiratory elastance and resistance, respectively, as a result
of pulmonary disease.
A new PAV system using a proportional solenoid valve to
control the air supply to patients suffering from respiratory disabilities, was studied.
The outlet flow and pressure from the valve at various air-supply pressures were
tested and proven to be suitable for pressure and flow control in a PAV system.
In vitro tests using a breathing simulator, which has been proven to possess the
general characteristics of the human respiratory system in spontaneous breathing
tests, were conducted and the results demonstrated the viability of this PAV system
in normalizing the breathing patterns of patients with abnormally high resistances
and elastances as well as neuromuscular weaknesses.
In vivo tests using this
PAV system were also conducted on healthy volunteer subjects with artificial resistance
and elastance incorporated.
The test subjects felt comfortable to breathe, with
reduced breathing effort when PAV was active, demonstrating the positive assist
effect of PAV.
Size: 1,077 kb
Paper DOI: 10.2495/978-1-85312-944-5/10
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