围手术期小型猪模型 z-bo 2020-10-13 338

　　(1) Intravenous injection

　　1. Purpose of intravenous infusion The purpose of hydration during anesthesia is to maintain open venous access, provide circulatory support for oxygen supply, replenish detectable fluid loss, replenish undetectable fluid loss, and make fluid progress. Including supplementary losses. In emergency situations, intravenous access facilitates drug delivery and ensures rapid and effective drugs. Delivery of oxygen to the tissues is very important for maintaining aerobic metabolism, but not only does it require sufficient cardiac output to efficiently deliver oxygen to the tissues. You also need enough hemoglobin to combine with oxygen. Therefore, it is not enough to provide sufficient hemoglobin concentration and sufficient circulating blood volume. Anesthetized and awake animals have the same fluid requirements, depending on their physiology and morbidity (such as heart disease). Therefore, different hydrating therapies should be prescribed for animals with different conditions.

　　2. Commonly used infusion (1) 0.9% sodium chloride solution (normal saline): Normal saline is an isotonic and imbalanced electrolyte solution containing Na +, Cl- and water. Yes, it is the most commonly used body fluid supplement in veterinary clinics. Isotonic dehydration is very effective without losing water and electrolytes. (2) 5% glucose solution: the crystalline solution is an isotonic solution of glucose in water. After injection, the glucose in the solution is quickly absorbed by the cells and participates in metabolism. Since glucose molecules only play a temporary osmotic effect, a 5% sugar solution is not suitable for volume expansion, because the released free water is evenly distributed throughout the body.

　　(3) Ringer's solution: Ringer's solution is an isotonic balanced electrolyte solution. In addition to water, Ringer's solution also contains sodium, potassium, chlorine and calcium. Because the composition of Ringer's solution is similar to that of extracellular fluid, it is the most commonly used sodium-containing crystal solution, which can restore the amount of extracellular fluid and maintain normal cell function during injection. Useful for... At the same time, it has the functions of thinning blood, reducing viscosity, improving microcirculation, replenishing electrolytes and correcting acidosis.

　　(4) Hermann's Solution (Lactylinger's Solution): Hermann's solution is an isotonic electrolyte balance solution, similar to plasma electrolyte concentration. In addition to water, Hermann's solution also contains sodium, potassium, chlorine, calcium and lactic acid. Lactic acid can be metabolized by the liver to form bicarbonate. If the liver's ability to metabolize lactic acid is low, it will cause acidosis. Therefore, a similar electrolyte balancing solution containing other buffer salts (such as acetate) can be used. This solution does not depend on liver function, but is metabolized to bicarbonate, so it can be used for animals with liver dysfunction. it can. In addition, Hermann's solution contains calcium and should not be mixed with blood products for injection. Blood clots will quickly form after mixing. (5) 0.18% sodium chloride-4% glucose (glucose normal saline): If adding glucose normal saline for a long time, potassium must be added. Glucose saline does not promote vasodilation, because the free water released is evenly distributed throughout the body. (6) 7.2% sodium chloride solution (hypertonic salt solution): 7.2% sodium chloride solution is a hypertonic electrolyte non-equilibrium solution, and the hypertonic salt solution contains Na +, Cl- and water. It is mainly used to quickly replenish blood volume, and has the effect of increasing the contractility and output of the heart.

　　3. Many anesthetics are metabolized in the liver and excreted in the kidneys. With enough body fluids, these processes can proceed smoothly. Therefore, it is very important to provide circulatory support for animals during the anesthesia and recovery phases. For animals under general anesthesia, the injection rate of conventional balanced isotonic crystals should be 5-10 ml/(kg·H). In anesthetized animals, this "maintenance rate" is higher than that of unanaesthetized healthy animals [1-2 ml/(kg·H)], which not only compensates (increases) the perceptible or unperceptible fluid loss. When anesthetics produce hemodynamic effects, it can also provide circulatory support. Some experts use the normal fluid retention rate [2 ml/(kg?H)] at the beginning of anesthesia, and it is based on the sensory awareness of the severity of the operation (mild, moderate, and severe surgical trauma). It is recommended to increase the dose during surgery. It has increased by 5ml/(kg?H), 10ml/(kg?H) and 15ml/(kg?H). Regardless of the dose, the animal's response to the adjuvant should be continuously monitored to adjust the rate of infusion. In the process of clinical anesthesia, the maintenance rate of anesthesia can be appropriately increased for animals with very large original loss and/or animals that have not been corrected before anesthesia and continue to lose. However, in animals with a slower fluid loss, it can cause rapid hydration of hydrated plasma proteins and electrolytes. Therefore, it is recommended to choose this rehydration method at least 4-6 hours after anesthesia.

　　（2）Insulation

　　The skin operation preparation of mini-pigs, surgical disinfection, the dilation of the surrounding blood vessels by chemicals, the influence of fluid exchange during the operation, a large amount of cleansing fluid is the reason for the reduction of the body temperature of mini-pigs. The rectal temperature should be continuously monitored during all operations. For small pigs, the temperature should be higher than 36°C (normal body temperature range: 38-39°C). Perioperative body temperature care is mainly carried out from the following viewpoints. First, adjust the temperature of the operating room. During the operation, the temperature in the operating room should not be too high. Otherwise, the surgeon will not only feel discomfort, but bacteria will also grow. Risk of contamination of surgical wounds. It is best to control the temperature of the operating room at about 24°C, and the relative humidity should be kept between 40% and 60%. Second, reduce animal contact before and after surgery. Animals should be kept warm enough when entering and leaving the operating room to isolate them from the surrounding cold air. Third, the operating table must have a heating function or use an electric blanket to heat the animal. Fourth, during anesthesia or surgery, the surgical site should be exposed, and the non-surgical sites (especially the limbs and injection sites) should be covered with good insulation materials or surgical towels to reduce heat dissipation from the skin. Have. Fifth, infusion of liquids or blood products preheated to 36-37°C is safe and comfortable, and will not affect the composition of the liquid. It can effectively prevent the body temperature from falling, but it should be noted that certain drugs cannot be heated. Sixth, if it is necessary to clean the body cavity or wound during the operation, heat the cleaning solution to about 37°C to prevent the towel covering the animal's body from being immersed in the cleaning solution and generating excessive heat in the body. The movements must be kept gentle to avoid a drop in body temperature during the operation.

　　(3) Anesthesia monitoring

　　Anesthesia is monitored by monitoring heart rate and blood pressure. This method is more accurate than observing the reflexes of muscles and eyelids. ECG monitoring should be carried out during the entire operation, because the anesthesia of miniature pigs is very easy to cause arrhythmia during anesthesia. During the induction of anesthesia, the action of anesthetics may cause respiratory depression, and then hypoxia and hypercarboemia. During this period, the monitor should check the pulse, observe the color of the mucous membrane, observe the replenishment time of capillaries with gum fingering, and observe the depth and frequency of breathing.

　　1. The depth of anesthesia is a common method to determine the depth of anesthesia through the eyelid reflex, eye position and muscle tension of the massager. It is not easy for miniature pigs to observe eyelid reflexes under anesthesia. This is mainly due to the deep eye sockets of the miniature pigs. The eyeballs of the miniature pigs are not deviated. In the middle position, the line of sight is not moving, the pupils are enlarged, and the light reflection is weakened or even disappeared. This indicates that the deep suppression is too deep and the anesthesia is too deep. Press down on the crown, tail and ear tip of the miniature pig and observe its muscle reflex. In addition, mandibular muscle contraction is considered to be a relatively accurate monitoring point for anesthesia, while tight and stiff mandibular muscles usually indicate a shallow depth of anesthesia.

　　2. Breathing focuses on observing breathing patency, breathing rate and breathing range. If the airway is not clear, the animal may have difficulty breathing, increased chest breathing activity, increased nose and even blue mucous membranes. During inhalation anesthesia, the tidal volume can be measured with a tidal meter. Deep breathing, shallow breathing and faster frequency are all signs of respiratory failure. If the tidal volume is found to decrease sharply, hypoxia will soon appear. Decreased tidal volume is a symptom of severe respiratory depression during anesthesia. The visible color of the mucosa reflects the current oxygen supply and peripheral circulation function. Observe the color of the mucous membranes of the gums and tongue to roughly determine the degree of hypoxia in the animal. However, anemic animals may also show mucosal cyanosis due to their very low oxygen saturation. You can measure the partial pressure of oxygen and carbon dioxide in the arterial blood to determine whether the animal meets the needs of oxygen inhalation and carbon dioxide excretion.

　　3. The circulatory system mainly uses non-invasive methods, such as pulse check, hearing, blood pressure measurement and ECG monitoring. Intraoperative pulse rate, sprint-like heartbeat, pale conjunctivitis and poor vascular filling are symptoms of shock. Slow pulse is mainly caused by excessive deep anesthesia and reflex blood pressure.

　　Four. The general situation is mainly to pay attention to changes in consciousness, response to pain and other reflexes, such as corneal reflex and eye position. When animals are shocked, their psychological reactions will become cold and even unconscious.

　　Fives. Thermoanaesthesia usually lowers the animal's body temperature by 1-2°C or 3-4°C. If the animal shows a strong stress response or does not adapt to certain drugs, it may cause a high fever.

　　6. Changes in body position will adversely affect breathing and circulation due to changes in body position. When the limbs are compressed or stretched, it can cause quadriplegia. (4) Commonly used first aid methods for small pigs

　　Due to individual differences in animals and the existence of potential diseases, miniature pigs are often in danger during surgery and anesthesia. Timely and appropriate rescue measures will be taken to treat the accident during the operation. It is very important to save the lives of animals and retain the experimental data and materials of the animals. The following are some first aid measures in dangerous situations:

　　1. If the respiratory insufficiency is caused by intraoperative or intraoperative congestion in a miniature pig with respiratory insufficiency, tracheal intubation should be performed in the miniature pig immediately (for methods, please refer to endotracheal intubation). The catheter should be connected to the artificial respiration balloon immediately after the infusion. , It is one person's responsibility to pinch the artificial respiration airbag (about 15 times/min). Another person immediately turned on the ventilator and external oxygen, set the ventilator parameters, quickly separated the artificial respiration balloon from the catheter, and then connected the catheter to the ventilator to help the animal breathe. .. After turning on the ventilator, you can inject 10 mg/kg of Nixen injection into the animal experiment muscle to stimulate the respiratory center, and intravenous injection of Flosid injection of 1-2 mg/kg can promote drug metabolism and excretion. And supplemented by intravenous infusion. Sodium bicarbonate injection can relieve acidosis.

　　2. Blood volume reduction During the operation of minipigs, excessive blood loss due to the operation will reduce the output of the heart. If your blood pressure drops, you will need to take different first aid measures based on the amount of blood lost. When the blood loss is small, the fluid flow in the venous channel can be accelerated, thereby increasing the body's blood volume. If you lose too much blood, you can inject hydroxyethyl starch to increase blood volume and increase blood pressure. If blood loss causes a sharp drop in blood pressure, it can be injected. Pressurized drugs (dopamine 1-5μg/min, Philippine hydrochloride, etc.).

　　3. During the operation of small-scale heart failure pigs, if the operation causes heart failure, different rescue measures should be taken for experimental animals according to different conditions. If a large amount of blood loss causes heart failure, it can be rescued by the following measures to reduce blood volume. If the heart develops ventricular fibrillation, it should be defibrillated with an ECG defibrillator. 1 mg of adrenaline hydrochloride is injected into the heart.

　　The dangerous situations that occur during mini-timba surgery are complex and diverse. The above are some common situations. In the process of minipig surgery, it is necessary to combine them according to the actual situation to save the endangered animals.