indeed.. saw the same thing while working as a trauma nurse.. those with bdly singed lungs can breath for a very limited time on their own but will die very quickly without some medical intervention.. One could argue that one reason that Anakin could breath enough to scream before th ehelmut was lowered is due to shock..
And yes Vaders suit does way more than control just his breathing
"Vader's life support system included a chest-worn, computerized control panel unit that regulated his respirational functions. Three slot like dataports offered diagnostic checks of his pulmonary, respiratory and neural systems. On his belt, Vader wore two small system function boxes. The one on his right featured a temperature regulation system. On his left, he wore a respiratory sensor matrix. The center buckle featured an audio enhancement unit built into the electromagnetic clasp. Durasteel armor protected his shoulders, upper ribcage and shins."