I'm playing through Bioshock Infinite at the moment and trying it on the hardest difficulty setting 1999'
It's not been too bad until I reached Lady Comstock, oh boy.
The graveyard encounter was okay thanks to the numerous medkits around. The bank encounter was made easier by staying behind a thick vault door. But outside the house was a major pain in the proverbial.
I checked various sites, watched videos and so many went with the run and hide technique that proved dicey. It was the bank encounter that provided me with the clue to a method that allowed me to win without once needing health.
Lady Comstock is restricted to her movements, she cannot step beyond the carts at the bottom of the steps. Except the dead soldiers she revives can. Ah but she can only revive and re-revive soldiers within her range. Getting the idea?
Head to the area with the machines and use the range boosted vigour "Undertow" to grab soldiers then kill them. If you run out of salts stay put and you only need to deal with the few melee soldiers before Elizabeth will throw you some. Use the Mosquito to whittle things down.
Once all the soldiers are piled up at your feet just let the Mosquito take her out.