IF YOU have had surgery, you may have experienced an unpleasant aspect of it that happens even before you are wheeled into the operating theatre. People are usually told they must have nothing to drink 鈥� 鈥渘il by mouth鈥� 鈥� for 2 hours before the surgery. But the 2-hour fluid fast tends to become longer, as operations are often delayed, meaning that people may go without anything to drink for several hours, sometimes even most of a day.
The good news is that things are changing. A new approach practised in a few hospitals around the world lets people continue drinking small amounts of water or other clear fluids until the point they are sent to theatre. Now, its advocates want to spread the word so more patients get the benefits.
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The strict fasting rules before surgery were introduced in the mid-20th century because occasionally, while anaesthetised, people regurgitate some of their stomach contents and this can pass into their airways.
If food blocks the airways, it can cause suffocation. Even if only liquid is aspirated, stomach acid can damage the delicate tissues of the lung. So anaesthetists decreed that people should have nothing to eat for at least 6 hours before surgery, as well as nothing to drink for the last 2 hours. This became part of hospital guidelines in the UK, US and many other countries.
But in the past decade there have been growing calls to liberalise the rules on fluids. The latest incarnation is to actually encourage people to consume up to one glass 鈥� of about 150 to 170 millilitres 鈥� per hour of clear fluids such as apple juice until their operation, in a policy that in Scotland is called Sip Til Send.
The liberalisers have several motivations. Firstly, it has become apparent just how long some people are going without drinking under the current rules, because of the way that scheduled operations are delayed to fit in emergency surgeries. One of people having hip surgery found that more than half had gone 6 hours without fluids and more than a fifth had gone over 10 hours.
There is also growing awareness of the potential harms when people go into surgery seriously dehydrated. It not only makes them feel nauseous and miserable before and after the operation, but it can lead to worse medical outcomes, especially in those who are older or frail. Studies have suggested that cuts postoperative nausea and is linked with a of someone becoming delirious while recovering.
How about the risk from aspiration? It now seems this was overstated. More than half of people having emergency surgery have , yet the number who aspirate anything is very low.
In any case, a Sip Til Send approach leads to in the amount of liquid in the stomach, because clear liquids are emptied from the stomach very quickly. Ninewells Hospital and Medical School in the UK introduced Sip Til Send in 2021 and has seen no increase in aspirations. It has since helped more than 50 other hospitals in the UK, elsewhere in Europe and in Australia and New Zealand emulate this approach. US hospitals are usually more cautious about fasting rules.
It is understandable that medical staff may be reluctant to change something they have done for decades, especially when it contradicts safety guidelines. But it is past time for those guidelines to catch up with best practice, says an in February鈥檚 issue of Anaesthesia.
It may be that, in the future, doctors look back on the current rules as overly strict, akin to the way we used to forbid parents from staying with their children in hospital. When it comes to preoperative fasting, it seems to be time to rewrite the rulebooks.
Clare Wilson is a reporter at New Scientist. Follow her @ClareWilsonMed
