An ailing resident in a ritzy Upper East Side co-op building stabbed her home health aide in the gut during an argument over her oxygen mask, sources said. The 66-year-old resident of 210 East 73rd St. knifed the unidentified, 54-year-old female aide, after the two argued over the mask on Saturday at about 12:30 p.m., sources told The Post. A resident of the building told The Post Saturday that he overheard the aide “speaking to what appeared to be her patient on the phone. The fight in the ritzy pad was allegedly sparked over an oxygen mask. The post Patient stabbed home health aide in fight over oxygen mask inside posh NYC apartment: sources appeared first on New York Post.