The previous times John Blyth Barrymore performs meaningful physical acts, it is described inside brackets. I think something similar to  `[Gasp.]` might be optimal, as your original description was short and impactful. However, I'm unsure if we can clearly convey the meaning without specifying that it is an action Barrymore performs. Because of that, I've attempted to mimic your previous eloquent writing while separating the gasp into the shortest possible sentence. I am open to suggestions.