by A Cassandra.
like CPAP but better
CPAP Continuous Positive Air Pressure is a medical technique that was traditionally used to treat sleep apnoea. It is now also used to help keep covid patients off a ventilator.
IPAP Intermittent Positive Air Pressure. Will use the same type of mask as CPAP to provide air/oxygen at a positive pressure, to help inflate the patient's lungs, but only when he is breathing in. Then as the patient breaths out the pressure in the mask will be dropped back down to atmospheric pressure. This will be under the control of the patients breathing.
The mechanism for this is 1) A rapidly acting valve, releasing brief pulses of air/oxygen, at higher than normal CPAP pressures. 2) A second valve to release the exhaled air. 3) A microcontroller, to coordinate the valve actions. 4) A responsive pressure sensor, inside the face mask, generates the control signals to entrain the actions to the patients breathing.
The sequence of actions, starting at the beginning of an inhalation, is as follows:
1) The patient starts to breathe in, and the pressure inside the mask falls below atmospheric pressure.
2) This causes valve one to release a small puff of air. NB the volume of this air, after it, as returned to atmospheric pressure, should be 1% of the tidal volume.
3) As soon as the pressure in the mask rises above the atmospheric pressure valve one is shut off.
4) As this small puff of air expands, it converts the potential energy of pressure into kinetic energy as it accelerates air down the patient's windpipe.
5) The patient continues to breathe in, and steps 1 to 4 are repeated about 100 times.
6) Once the patient has breathed in enough, they naturally stop breathing in.
7) When the air pressure in the mask is above atmospheric pressure for a twenty-fifth of a second the microcontroller opens the second valve, allowing the patient to breathe out.
8) When the air pressure in the mask falls to just above atmospheric pressure the second valve is closed and the cycle can begin again.