Lothian NHS Board has been warned to shake up high dependency care procedures after a diabetic patient died of a heart attack which could have been caused by a leaking intravenous central line.

In a damning report, the Scottish Public Services Ombudsman (SPSO) found the patient's care and treatment in the high dependency ward of Western General Hospital in Edinburgh was "below a reasonable standard" while its clinical advisers criticised the board for not taking necessary follow-up action.

They say the line which provided fluid nutrition and insulin for the diabetic patient, known as Mr C, was switched off because of a leak.

While insulin continued to be provided, the nutrition supply had stopped - sending the patient's blood sugar levels plummeting dangerously.

The patient was admitted to Edinburgh's Western General in July 2006 for a bowel operation but his condition deteriorated and he was admitted to ward 58, a high-dependency unit.

Clinical advisers to the SPSO, made up of a consultant hospital doctor and a nurse consultant who specialise in intensive and high-dependency care, said the central line leak in ward 58 may have caused the 64-year-old patient's heart attack but they were unable to comment on much of the nursing care provided as so few records were kept on the patient. It was described in the report as "an unacceptable standard of nursing practice".

One of the patient's daughters noticed her father's gown was wet as the central line - which is inserted into a vein in the neck - was leaking during a visit on August 4, 2006.

The SPSO was told that when she reported it, the nurse switched the line's pump off, saying: "It won't leak now."

In a letter to the patient's wife, the board said they could not say whether the nurse had made the remark and said there was no evidence to suggest that switching off the central line was detrimental.

But the SPSO's clinical advisers said the board "should not ignore the possibility of a link between the significant upset to the patient's metabolism and, a few hours later, his cardiac arrest".

They were concerned the board appeared "never to have acknowledged any shortcomings arising from the leaking line and, therefore, never to have learnt any lessons from this".

The board, did not appear to recognise "any adverse consequences from the stopping of the nutrition at 4pm because of the leaking line".

The report said: "There was no evidence that the board had at any time identified any concerns arising from the leaking central line and there was evidence that part of their investigation of the complaint had been less than rigorous."

SPSO advisers said there was a failure to recognise any wider implications when nutrients were stopped at 4pm.

It was not until 10pm that a doctor arrived and gave the "agitated and confused" patient sugar. Several hours later the patient suffered a cardiac arrest and died.

The board said that before the incident, it was noted that the clinical leadership of Ward 58 was "less than robust".

The senior nurse in charge was no longer employed and the chief nurse reported that steps had been taken to improve nursing standards.

"We accept that, on Ward 58, Mr C did not receive an acceptable standard of care, the clinical leadership was less than acceptable and the documentation of care for complex cases was inadequate," said the board.

Libby Campbell, associate director of nursing for NHS Lothian, said: "We would like to take this opportunity to apologise to the family of Mr C for the distress caused.

"We accept the recommendations in the report and have already taken several steps to prevent a repeat of similar incidents.

"Since this incident two years ago, we have carried out a robust review of patient monitoring."