Here is a link to portable concentrators - http://www.portableoxygensolutions.com/portable-oxygen-concentrator-comparison-guide/
Those listed as pulse only will NOT work with CPAP.
There is no net increase in oxygen when in the same room with you because the machines send the oxygen through the tubing and release the waste, which is mostly nitrogen minus the oxygen.
There is a potential fire hazard to the recipient because their clothing or bedding contains a higher than normal concentration of oxygen and any spark could start a fire.
You can check the power requirements for any given model by going to the manufacturer's website - 3 amps of power from a 120V circuit will require at least 30 amps of 12 V power using an invertor. Battery operated portables will not run for 8 hours on battery alone.
portables