Since the deaths, however, he has been engaged in countless conversations with investigators and is helping to coordinate a so-called ''plan of correction,'' a comprehensive account for state investigators on how the hospital intends to change the way it does business. Dr. Aston did not return repeated calls, and Dr. Mellen, the anesthesiologist assisting him, declined to comment, citing legal concerns. The hospital's corrective measures after the two deaths are causing a controversy of their own. Since Feb. 17, doctors have been told they must give patients under general anesthesia additional breathing help, usually a breathing tube, said doctors at the hospital, who view the practice as excessive. Dr. James E. Cottrell, the former president of the American Society of Anesthesiologists and the chairman of anesthesia at Downstate Medical Center in Brooklyn, said that there were problems with using a breathing tube, including possible damage to the teeth, throat and vocal cords, nausea and lengthening recovery time.
