Public health

‘Nil by mouth’ before catheterisation called into question

The conventional wisdom of making patients fast before cardiac catheterisation is being challenged by researchers who say the practice is not evidence based and comes with multiple fasting-related adverse effects on patient wellbeing.

While being a common protocol, there is “no published evidence” to support the practice which commonly causes hunger, headache and other complications, according to findings presented at the Cardiac Society of Australia and New Zealand (NZ) annual scientific meeting in Christchurch on 14 June.

Over a six month period, fasting-related complication rates were measured in 1030 patients set to undergo cardiac catheterisation for coronary angiography and angioplasty at Auckland City Hospital.

All patients were kept nil by mouth before catheterisation, but the fasting time varied widely between patients, with some having six hours fasting and others 18 hours fasting. The most common period was 14 to 16 hours (16% of patients) followed by eight to 10 hours (14%).

Pre-hydration using intravenous fluids was only used in 11% of the group, the researchers found.

Almost half the group experienced hunger, 12% experienced headache, 6% had hypotension and 4% had hypertension, found cardiac specialist nurse Sheila Bacus and colleagues at the hospital’s Greenlane Cardiovascular Service. Other side effects identified included nausea (4% of patients) arrhythmia (1.3%) and hypoglycaemia (0.7%).

Most patients had pre-existing hypertension (72%), one quarter had diabetes (26%) and almost a quarter had stage 3 or worse kidney disease (23%).

The researchers said their real-world findings identified that the duration of fasting was “much longer than anticipated” and discomfort from hunger and headache was a common side effect.

“These data support the need for further research into the use of routine fasting prior to cardiac catheterisation,” Bacus and her co-authors concluded.

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