You are permitted to take medical equipment on board if it is essential for your journey. Before travelling, you must contact the airline to make sure they know you will be carrying medical equipment and to check any requirements that may apply to it.
You should also check with your departure airport that you may take the equipment through the security control, and whether there are any special requirements. Do not forget to check the requirements at the airport from which you will return, and at any intermediate airports where you may stop on your journey.
Take with you the doctor's certificate that explains your need to use the equipment. You may also have to show the certificate to the security staff at the airport. The equipment will normally be sent through the security scanner in a separate box.
Battery-operated equipment must have battery capacity for the whole flight. You must take spare lithium batteries with you into the cabin, as they are not allowed in luggage.
The usual requirements apply to passengers’ electronic equipment during flight and you will not normally be allowed to use it during take-off and landing. Some devices have been tested and approved for use during the whole flight, but you must contact the airline in advance, to ensure that they know you will be carrying medical equipment and to check for any additional requirements.