This is just an idea and would require a feasibility study to confirm whether it is workable and useful. The idea is to use ultrasound to convert fluid building up in lungs into a mist that the lungs can more readily expel, rather like cigarette smoke.
Ultrasonic transducers have been used for many years to make fog or mist for trivial theatrical effects and garden ornaments. Even cheap transducers from Amazon can convert 400ml of water to mist per hour each.
It is also commonplace in radiation treatment to overlap beams from different directions so that normal tissue is unharmed but intensity is high enough to achieve the desired effect where it is needed. This would work for ultrasound beams coming from different directions too. That would prevent fluid from being misted in the wrong places.
Another existing technology used for ultrasonic loudspeakers uses interference between beams from multiple transducers to create audible effects at any point in space.
My suggestion is to combine these existing technologies to make a close-fitting vest or harness fitted with an array of ultrasonic transducers that could be worn by patients suffering fluid build up in their lungs. Conventional ultrasonic imaging could identify locations of fluid build up and then ultrasonic beams could then be targeted precisely to convert some of that fluid to mist, allowing it to be ejected more easily from the lungs during breathing, instead of building up and effectively drowning the patient. Whole regions could be scanned to mist from large volumes at once, or different amounts of mist could be produced from particular problem areas. The effect would presumably look similar to people breathing out cigarette smoke. The rate at which fluid could be converted to mist is far greater than the rate at which it builds up, so even though not all of the mist would be ejected, it could still achieve the goal.
This might not work. It may be too hard to cause misting in fluid not in direct contact with a transducer. It may be too difficult to cause misting of problem fluid without causing problems in nearby tissue or bubbles in blood vessels. Obviously a lot of engineering design would be needed even if it could work, but expertise to do that is out there and suitable vests could possibly start be manufactured within months.