Medical science: why fast before anesthesia?
”Doctor, I followed your instructions, neither ate nor drank water, so I ate buns and drank milk so I would have the strength to survive the surgery and anesthesia, you see I am smart enough, right?” The doctor simply fainted.
Some people may think that eating something before surgery to have the strength to survive the surgery and anesthesia is, unfortunately, wrong; eating or drinking will only lead to the cancellation or delay of the surgery. The cost of withholding food could be life! Because vomiting can occur if there is food in the stomach after anesthesia, vomiting that occurs after anesthesia can be fatal!
Except for local anesthesia, before receiving all anesthesia, you must abstain from eating and drinking, that is to say, neither eat anything, nor drink anything, including water, do not mention to me buns of milk.
Why are doctors so “cruel” as to make patients hungry for surgery and anesthesia?
Under physiological conditions, the lower esophageal sphincter at the junction of the esophagus and stomach acts as a gate to prevent food and stomach acid from returning to the esophagus and mouth.
Swallowing is a very fine and complex and ingenious reflex action that ensures that when eating and drinking, food goes down the esophagus into the stomach and not into the trachea.
If this reflex action is disrupted, for example, choking on water, it is because a small portion of water has entered the tracheobronchial tube, or water has choked on the lungs. There are very sensitive receptors on the tracheobronchial tube, and once stimulated by water or other foreign bodies, the cough reflex is immediately triggered to clear the foreign body inside.
Once anesthetized, all three of these protective physiological functions are disrupted.
①The lower esophageal sphincter is relaxed and does not act as a gate, and the stomach contents reflux into the esophagus and mouth.
(ii) The swallowing reflex is disrupted, and food may enter the lungs as long as it is present in the pharynx.
(iii) The cough reflex is suppressed, and foreign bodies that enter the trachea cannot be cleared out by the cough reflex. The consequence is that food and stomach acid enter the lungs, resulting in immediate death by asphyxiation in severe cases and death or aspiration pneumonia within a few weeks in mild cases.
The latest anesthesia fasting guidelines recommend the 2468 principle for the duration of preoperative fasting.
2: Small amounts of water may be consumed 2 hours before anesthesia.
4: Breastfed infants can be breastfed 4 hours before anesthesia, or 6 hours in the case of milk.
6: Light food, which is easily digestible carbohydrates without fat and meat, such as toast, buns, and thin rice, etc., is fasted for at least 6 hours.
8: ordinary food fasting for at least 8 hours.
The above is the minimum fasting requirement, which is applicable to all anesthesia except local anesthesia, including anesthesia for surgery and examination, such as painless gastroscopy and painless abortion, etc. If there are pre-existing gastrointestinal diseases or diseases affecting gastrointestinal motility, the above recommendations do not apply, please consult your doctor.
The current prevailing crude medical model does not allow for meticulous care of each patient and patients often fast for too long, but patients are not advised to decide on their own how long to fast, as this may disrupt the normal operation of the medical facility.
The requirement to fast and drink does not apply to medications taken for long periods of time, such as those for hypertension and coronary heart disease.