The incident, which took place at the Lidköping hospital, has prompted stinging criticism from Sweden's National Board of Health and Welfare (Socialstyrelsen).

The 72-year-old went under anesthetic at 10.45am on the day of the operation, which took place in January 2011.

At noon sharp, the head anesthetist left the operating room to go for lunch. Fifteen minutes later, the head nurse anesthetist also left the patient and went for lunch.

No other anesthetist was called in to take over responsibility for the doctor who was on his lunch break.

And while another nurse was brought in to cover for the nurse anesthetist, the nurse who arrived came from the orthopedic ward and wasn't familiar with the respirator to which the 72-year-old was attached.