Volumetric infusion pump, or syringe driver? Or ambulatory syringe driver?
Any modern infusion pump should be able to handle ambient pressure variations (within reason) I would have thought. Although I would suggest an element of "clinical observation" during such a flight anyway.
A syringe driver would be relatively immune from atmospheric influences, I should imagine.
Perhaps you're not at liberty to mention the clinical circumstances, but that is the area with which I would be most concerned
vis-à-vis safety issues. Things like:- is the patient a stretcher case, or travelling in a normal seat? Awake and alert ... or not? Accompanied by nursing or medical staff (I hope) ... or not? Stuff like that.
Also ... what about power (for the pump)? Is battery capacity sufficient for the journey planned ...
etc.? 