Pre-operative fasting guidelines: an update.
Liberal pre-operative fasting routines have been implemented in most countries. In general, clear fluids are allowed up to 2 h before anaesthesia, and light meals up to 6 h. The same recommendations apply for children and pregnant women not in labour. In children <6 months, most recommendations now allow breast- or formula milk feeding up to 4 h before anaesthesia. Recently, the concept of pre-operative oral nutrition using a special carbohydrate-rich beverage has also gained support and been shown not to increase gastric fluid volume or acidity. Based on the available literature, our Task Force has produced new consensus-based Scandinavian guidelines for pre-operative fasting. What is still not clear is to what extent the new liberal fasting routines should apply to patients with functional dyspepsia or systematic diseases such as diabetes mellitus. Other still controversial areas include the need for and effect of fasting in emergency patients, women in labour and in association with procedures done under 'deep sedation'. We think more research on the effect of various fasting regimes in subpopulations of patients is needed before we can move one step further towards completely evidence-based pre-operative fasting guidelines.