Coroner rules doctor errors led to grandmotherâs death Three errors made by a well meaning doctor have led to the death of a grandmother who was suffering significant pain from a neck condition, a coroner says. Health by Grace Mason Premium Content Subscriber only THE "preventable" death of a Redlynch grandmother who was given a huge dose of morphine by her GP and friend before lapsing into a coma and cardiac arrest was due to "poor judgment" and "well meaning error", a Cairns coroner has ruled. Margaret Cahill, 61, died at Cairns Hospital on September 13, 2017 two days after Dr Barbara Gynther gave her a 60mg dose of morphine to treat debilitating pain caused by a nerve root compression in her neck.