David Simpson, a diabetic with heart problems, was taken to the emergency department after collapsing at his GP's on Wednesday morning.
He was admitted to hospital, only to be discharged on Thursday without knowing what the ''plan'' was for his sore foot.
It was not until yesterday, when he went to take a shower, that he noticed the cannula had not been removed.
''You can't just walk out of a hospital. You've got to get the paperwork,'' Mr Simpson said.
Last week, Mr Simpson had had an operation to cleared blocked arteries in his leg that were affecting his foot.
The ''very tricky'' operation took place about 1pm on Friday and he was discharged about 10am the next morning, which was ''disgusting'', Mr Simpson's daughter, Barbara Byers, said.
Mrs Byers said it was all about getting people in and out of hospital as quickly as possible and it was not good enough.
''They've just thrown him out with nothing,'' she said.
Yesterday, when the cannula was noticed, Mrs Byers rang the hospital and was told a district nurse would be sent out to remove it. But then the hospital rang back to say the nurse could not be sent out until the next day.
The family was told to either bring Mr Simpson to the hospital, or take him to the GP.
Mrs Byers took her father back to his GP where the cannula was removed by a nurse.
The discharge papers were being posted from the hospital to Mr Simpson, the family was told yesterday afternoon.
''They are going to review it [Mr Simpson's condition] in two weeks' time. He has to go back to his GP if something happens in the meantime,'' Mrs Byers said.
Nursing and midwifery director Leanne Samuel apologised to Mr Simpson in a statement released yesterday.
''We have been advised that a patient has been discharged from Dunedin Hospital with a cannula still in his arm.
''This does not meet the hospital's expectations as to standards of care and we apologise for that.
''We appreciate that the patient has concerns as to the care he has received and we are contacting him to discuss these matters,'' she said.
