It refers to hospital doctors who, forced to work long hours which violate Labor Standards Law such as working continuous 72 hour shifts, despair at the lack of improvement in working conditions and resign.
72時間連続の当直明け勤務など、労働基準法に違反する長時間労働を強いられている病院の医師が、待遇が改善されずに絶望して辞職することを指す。