1 Preoperative fasting
Preoperative fasting is to avoid aspiration pneumonia or asphyxia caused by reflux of stomach contents during anesthesia, which is especially important for abdominal surgery under general anesthesia. The traditional fasting time is 12h before operation, and drinking is prohibited. However, in clinic, many factors such as enema make patients wait for surgery on an empty stomach for a long time, which easily leads to hunger, anxiety and discomfort, reduces the body's resistance, not only affects patients' sleep, but also easily leads to hypotension during anesthesia induction and affects patients' prognosis. The main factors causing reflux and aspiration are satiety and delayed gastric emptying. The main factor affecting gastric emptying is the amount of gastric contents, followed by the types of gastric contents. Solid emptying is slower, liquid emptying is faster, and fat delays gastric emptying. According to reports, in the 1980s, it was measured from healthy volunteers that the stomach contents were rapidly emptied at 10 minute after drinking fruit juice, and the stomach contents were insufficient at 1h, while the stomach contents were slowly emptied after eating solid food, with only 50% left at 2 hours and less than 20% at 3 hours. However, the average retention of liquid in the stomach of healthy people after drinking clean fruit juice is 10 ~ 30 ml, and rarely exceeds 10~30ml. Therefore, in the case of normal gastrointestinal function, it is difficult to have gastric reflux and lung aspiration.
In view of this, in recent years, Norway, Sweden, the United States, Canada, Britain and other countries have revised the preoperative fasting regulations. Healthy people only need to fast solid food for 6 hours or eat juice for 2 hours before elective surgery; Generally, drugs affecting gastric emptying were not used before anesthesia induction1h. When taking these drugs orally, the allowable drinking water amount is150ml; . Opioid drugs prolong gastric emptying time. If the preoperative drugs are opioids, water should be banned for 65438±0h hours before anesthesia. Clinical practice has proved that clean juice can be freely drunk 2 hours before elective surgery anesthesia, but milk and other fat drinks are not included.
Reducing fasting time can avoid unnecessary delay or cancel some elective operations, reduce dehydration and hypoglycemia caused by long-term fasting, and reduce surgical stress and postoperative complications. However, the following situations are not suitable for this new regulation: such as all emergency operations, gastrointestinal obstruction, upper digestive tract cancer, esophageal hiatus hernia, functional dyspepsia, psychological tension and so on. These cases should still follow the old rules of fasting12 hours and drinking for 4 hours before operation to prevent the risk of lung aspiration or suffocation during tracheal intubation and rapid induction anesthesia.
Postoperative hypothermia
Usually, medical staff only pay attention to whether the patient's body temperature rises, but often don't pay attention to the situation that the postoperative body temperature is lower than 35℃. In fact, persistent hypothermia is harmful to the human body, which will cause coagulation diseases and lead to increased bleeding; Reduce metabolic rate, reduce oxygen supply to the body, leading to acidosis; Immune function is impaired, especially the oxidative killing effect of neutrophils is reduced, which reduces the body's resistance to wound infection and leads to an increase in wound infection rate; In addition, it will damage the function of heart, liver and kidney organs, and often lead to death in severe cases.
The main reason of perioperative hypothermia is that (1) anesthetics can inhibit thermoregulation. Anesthesia inhibits the mechanism of vasoconstriction, trembling and non-trembling thermogenesis. (2) massive blood transfusion. Every time an adult is infused with 1L normal temperature liquid or 1u(200ml) cold blood, his body temperature drops by 0.25℃. (3) Low temperature environment. (4) the body cavity is open. During the operation, the incision was exposed for too long and the water evaporated. Because abdominal surgery under general anesthesia is mostly major surgery, the operation time is long, and the above factors that cause hypothermia often coexist, it is very necessary to take active preventive measures during perioperative period. For example, (1) intraoperative coverage should be strengthened to avoid unnecessary exposure; Cover the skin with a warm blanket after the operation. Pressurized gas can be used to heat the quilt if necessary. (2) In order to keep a warm environment, the operating room temperature should be controlled at 24℃ ~ 27℃. (3) Give oxygen in time (pay attention to humidification). (4) Strengthen body temperature monitoring. For people with hypothermia, use a thermometer that can measure the rectal temperature below 35℃. (5) When hypothermia occurs, ① raise the ambient temperature and keep the temperature in the ward at 22℃ ~ 28℃; ② Cover the quilt to keep warm; (3) intravenous drip heating to reduce temperature drop. When a large amount of liquid is input, the liquid can be heated in water at 50℃ for infusion. If possible, the deep body temperature can be raised by heating technology, and the liquid or blood products can be heated to 36℃ with a constant temperature heater before being input into the patient. This will not have adverse effects on drugs and blood products, nor will it cause the loss of body heat, which is conducive to the recovery of body temperature. (4) If the body temperature is below 35℃, you can add a hair dryer or a baking lamp, and wrap it with an electric blanket if necessary, but be careful not to burn the patient.