Clear drinks until two hours before an operation, rather than nothing from midnight

The guideline. The European Society of Anaesthesiology's 2011 guideline recommends that adults and children "should be encouraged to drink clear fluids up to 2 h before elective surgery", that solid food be stopped six hours before, and that these recommendations also apply to people with obesity, reflux or diabetes. A carbohydrate drink in the hours before surgery is part of enhanced recovery pathways. A meta-analysis drawing on 44 randomised trial reports in major non-cardiac surgery found carbohydrate loading shortened hospital stay by about half a day (mean difference 0.56 days, 95 per cent confidence interval 0.02 to 1.10) compared with fasting or placebo; its authors note that the guideline recommendation rests on low-quality evidence. The evidence that short fasting is safe is stronger than the evidence that it changes outcomes, which is why the grade here is moderate.

The measured gap. In a prospective study of 50 women having elective breast cancer surgery, the mean fast was 15.1 hours for food and 12.1 hours for fluids, far beyond the recommended six and two; the study found no correlation between fasting length and discomfort or complications. An audit at the University of Gondar Hospital in Ethiopia found 92 per cent of patients fasted from food and 95 per cent from fluid for longer than recommended, with a mean fluid fast of 12.7 hours. Long fasts usually happen because a whole list is told to fast from midnight, whatever time each person's operation will be.

The upgrade is a rule that each patient is told a time to stop drinking based on their own expected start, and is given a drink if the list runs late.