Gas embolism is the most dangerous complication of abdominal insufflation. Carbon dioxide and nitrous oxide are used for insufflation in endosurgery. Previously, air, oxygen, and helium were used in endosurgery (mostly in animal experiments). The latter is unsuitable primarily because it causes severe hypercapnia. Air and oxygen are considered unsuitable due to their potential for oxidation, the frequent development of subcutaneous emphysema, and its slow absorption from tissues. Furthermore, the use of oxygen precludes the use of an electric knife in the abdominal cavity due to the risk of fire or explosion. The physical significance of gas embolism, described below, further justifies the contraindication to the use of air and, in our opinion, nitrous oxide. In abdominal insufflation, gas can enter the bloodstream through puncture of a large vessel with a Veress needle, through open venules, or through an open hepatic sinus. A factor that promotes gas embolism is hypovolemia, in which venous pressure is often negative compared to atmospheric pressure. Therefore, with little venous return to the right atrium, the latter draws blood from the veins. At the same time, an artificial increase in intra-abdominal pressure by 15-16 mmHg compared to atmospheric pressure creates ideal conditions for gas to enter the bloodstream under the three conditions mentioned above. The pathological effect of gas embolism depends on the following factors: a) the volume of the gas embolus; b) the rate of gas infusion; c) the properties of the gas; d) the gas environment of the body. In terms of endosurgery, information on the nature of gases in general and their solubility in the blood is of primary importance. At a body temperature of 37 degrees Celsius and an atmospheric pressure of 760 mmHg. 100 ml of blood can dissolve 53 ml of carbon dioxide, 2.3 ml of oxygen, and 1.2 ml of nitrogen (the solubility of argon in blood is 200 times less than that of carbon dioxide). Therefore, carbon dioxide embolism is the least dangerous. Air contains 79% nitrogen, so air embolism is almost as dangerous as nitrogen and nitrous oxide embolism. Experimental studies on animals show that gas embolism does not occur with intravenous infusion of carbon dioxide at a rate of 25 ml per minute. In relation to the gas environment of the body in anesthesiology, the following extrapolation is interesting: if an air embolus with a volume of 1 ml enters the bloodstream, but the patient is anesthetized with nitrous oxide, nitrous oxide will begin to diffuse into an air bubble that does not contain nitrous oxide (according to Henry's law - the partial pressures of contacting gases are equalized), and the embolus volume will increase 3-4 times. If the patient is under intravenous anesthesia with artificial ventilation using an oxygen-air mixture (containing 80% oxygen), then when 1 ml of air enters the bloodstream, the embolus volume will decrease because nitrogen from the bubble will diffuse into denitrogenated tissue, and some of the oxygen from the embolus will be absorbed by the tissues. Most of the oxygen in the blood is bound to hemoglobin, so O2 will not diffuse into the bubble to replace nitrogen. The diagnosis of gas embolism during laparoscopic surgery is established by the following clinical signs: sudden hypotension, cyanosis, cardiac arrhythmia, hypoxia, the presence of the classic Morel-Lavall?e sign on auscultation, and a widened QRS complex on the electrocardiogram. Pulmonary edema is possible. If a significant volume of gas enters the vascular system, it blocks blood flow to the right side of the heart, causing death within minutes. Treatment of gas embolism should be prompt and include: 1) immediate desufflation; 2) artificial ventilation with pure oxygen; 3) lateral Trendelenburg position (steeply tilt the operating table toward the cephalic end and raise the right one by at least 15 degrees); 4) immediate puncture of the superior vena cava through the subclavian vein with insertion of a catheter into the right atrium and ventricle, aspiration of gas along with blood. To replenish blood loss, the blood aspirated after degassing can be reinfused; 5) if asystole has occurred and the diagnosis is clear - direct cardiac massage with simultaneous puncture of the right heart chambers for more effective removal of gas from its cavities. Pneumothorax and Pneumomediastinum One of the intraoperative complications of LN is pneumothorax and pneumomediastinum (Fig. 1). Gas may enter the pleural cavity due to diaphragmatic damage (traumatic or iatrogenic) or in the presence of large diaphragmatic hernias. Another cause of this complication is rupture of cysts or pulmonary bullae during forced inspiration. Pneumothorax manifests as a sudden increase in ventilatory resistance and vascular insufficiency. Immediate drainage of the pleural cavity is indicated to re-straighten the lung and eliminate tension pneumothorax. Pneumomediastinum may develop with gas insufflation into the preperitoneal or retroperitoneal space. It manifests as the appearance of subcutaneous emphysema in the neck and in the area of ??the jugular notch. Pneumomediastinum is rarely accompanied by life-threatening cardiac and pulmonary dysfunction. Hemocoagulation disorders: Attention to this problem has increased recently. ), increased intra-abdominal pressure during laparoscopy leads to compression of the inferior vena cava, limiting venous return from the lower extremities. The pressure in the femoral vein usually corresponds to the intra-abdominal pressure. Therefore, when PP is applied, blood pooling occurs in the lower extremities (Fig. 1D). Relative venous stasis was demonstrated by Doppler ultrasonography. In studies by Millard et al. (1991), it was found that pneumoperitoneum reduces blood flow velocity in the femoral vein by 37%. Slowing blood flow in the deep veins of the thigh and lower leg can lead to thrombosis with subsequent pulmonary embolism. Studies conducted in the USA demonstrated significant dilation of the lower leg veins after PP application. Venous stasis is aggravated by a change in body position with an elevated head end. Thus, J. Carpini et al. (1994) artificially created a reverse Trendelenburg position with an inclination angle of 45 degrees in experiments on volunteers. An hour later, a statistically significant increase in the calf vein diameter was detected, which was less pronounced in volunteers wearing compression stockings or elastic bandages. Stewart et al. (1990) demonstrated in a clinical study that intraoperative venous dilation of more than 20%, compared with preoperative levels, correlates with the development of thrombosis. Hypercoagulability also plays a no lesser role in thrombosis formation. Increased coagulability 24 hours after surgery was demonstrated on the thromboelastogram in patients after laparoscopic cholecystectomy (LC). This postoperative response was similar to that after open surgery. Therefore, LC, although considered a "minimally invasive procedure," induces early postoperative hypercoagulability, like traditional laparotomy. This may reflect the body's response to general anesthesia plus factors causing venous stasis. There are currently no reliable statistics to compare the incidence of thromboembolism (TE) after open surgery and laparoscopic cholecystectomy. Risk factors include age over 60 years, obesity, malignancy, history of thrombophlebitis of the extremities, and laparoscopic surgery lasting more than 2 hours. Prevention The Statement of the European Consensus Conference on the Prevention of TE in Surgery (1992) recommended the following measures, depending on the risk category (Table 1). The recommendations apply to both open and laparoscopic surgery. Table 1. Recommendations for the prevention of venous thrombosis in surgery. Risk category Recommendations Low Compression stockings, elastic stockings, and bandages can be used. Moderate Intermittent pneumatic compression or low-dose heparin. High Intermittent pneumatic compression and heparin. The low category includes patients with a score of no more than 1 according to Table 2. The average category includes patients with 2-4 points. The high category includes patients with more than 4 points. All applicable factors must be selected. Each factor is scored as 1 point unless otherwise noted. Table 2. Risk factor assessment for venous thrombosis and pulmonary embolism. Age 41-60 years Age 61-70 years (2 points) Age over 70 years (3 points) Expected bed rest for more than 72 hours. History of TE or TV (3 points) Varicose veins of the lower extremities Obesity (more than 20% of the predicted weight) History of surgery Immobilization - more than 72 hours before surgery Myocardial infarction Heart failure History of stroke Sepsis Laparoscopic surgery with pneumoperitoneum and reverse Trendelenburg position (more than 1 hour) Chronic obstructive pulmonary disease Surgery on the pelvic organs Air travel more than 4 hours in the first 6 days after surgery Fracture of the pelvic bones or large tubular bones Edema of the lower extremities, trophic ulcers, lymphostasis Tumors Pregnancy or the postpartum period (up to a month) History of pregnancy TE or TV in relatives Hormone therapy Expected duration of surgery more than 2 hours Increased blood clotting Other GENERAL RISK FACTOR There are many methods for preventing thrombosis, including Pharmacological agents such as heparin, oral anticoagulants, and dextran. Physical methods include elastic stockings, bandages, boots with intermittent pneumatic compression, and special shoes. Heparin, administered preoperatively subcutaneously in small doses (5000 units every 8-12 hours), is effective in preventing both venous thrombosis (VT) and thromboembolism. Although there is a small risk of bleeding, this method is considered quite safe. In contrast, oral anticoagulants and dextran are ineffective. Nevertheless, surgeons are quite reluctant to agree to preoperative heparin administration in laparoscopic surgeries, in contrast to open surgery. According to J. Arcelus et al. (1991), physical methods such as elastic stockings and pneumatic compression are most popular in the USA. In Europe, preference is given to drug prophylaxis. Physical methods are primarily aimed at eliminating venous stasis. On the other hand, pneumatic compression stimulates endogenous fibrinolysis. This method is safe and particularly appropriate for patients with potential bleeding or contraindications to anticoagulants. In what cases in endoscopic surgery are special methods for preventing venous thromboembolism and pulmonary embolism needed? Based on the information available in the international literature, there is no definitive answer yet. However, sufficient evidence has accumulated proving that laparoscopic surgery is associated with risk factors leading to venous thromboembolism and pulmonary embolism after surgery. These include general anesthesia with mechanical ventilation, the reverse Trendelenburg position, pneumoperitoneum, advanced age, and prolonged operative time. The same European Conference concluded that prophylaxis should be tailored to the severity of the disease and the degree of risk. A 30-year-old, non-obese woman probably does not require prophylaxis. On the other hand, a 75-year-old patient with acute purulent cholecystitis, prolonged bed rest, and a history of thrombophlebitis is a high-risk patient. Currently, specialists who are members of the American Surgical Society use prophylactic measures in 68% of patients undergoing laparoscopic cholecystectomy and 64% of patients undergoing open cholecystectomy. Physical methods are preferred. In contrast, European surgeons more often use low-dose heparin. Surgeons who have used the above-mentioned prophylactic measures note a sharp reduction in the incidence of hemorrhagic disorders in patients undergoing endoscopic surgery. Gasless Laparoscopy Since the first laparoscopic procedures were performed at the beginning of the century, the traditional method of creating the necessary space has been the creation of pneumoperitoneum. Its shortcomings and complications began to attract the attention of specialists only in the late 1980s, when the number of endoscopic procedures increased dramatically worldwide. In recent years, the range and duration of these procedures have changed. Indications have expanded to include elderly patients with serious comorbidities. The range of interventions has also expanded, from standard laparoscopic cholecystectomy to surgeries on the stomach and intestines, extrahepatic bile ducts, and retroperitoneal organs, as well as in oncology and pediatric surgery. The increasing complexity of surgeries has increased their duration under pneumoperitoneum. Since the late 1980s, gasless laparoscopy (GAL) has rapidly developed. In this technique, the abdominal wall is mechanically elevated using various devices inserted into or under the abdominal wall. Today, gasless laparoscopy is used for virtually all laparoscopic procedures, from gastric and intestinal resections to nephrectomy and surgeries on large retroperitoneal vessels. GAL has its advantages and disadvantages. The advantages include: - the absence of hemodynamic and metabolic disorders associated with carbon dioxide PP; — independence from the PP to create the necessary preposition (gas leak, poor insufflator performance, etc.); — absence of direct complications of PP, such as gas embolism, subcutaneous emphysema, pneumothorax, pneumomediastinum, postoperative shoulder pain; — the ability to use traditional general surgical instruments. To date, more than 10 different types of BGL elevators have been created worldwide. However, as was said at the 3rd Congress of the European Association of Endoscopic Surgeons (Luxembourg. 1995), none of them completely satisfies the operator. The disadvantages of BGL include the following: — PP provides uniform elevation of all 4 quadrants of the abdominal wall. With BGL, only 1 or 2 quadrants are visible; — the space created with BGL does not have the shape of a celestial dome, as with PP, but resembles a truncated pyramid. In this case, examination of the lateral sections of the abdominal cavity is difficult; — additional lifting devices are required. Nevertheless, gas-free technology has expanded the indications for laparoscopic surgery to include patients with serious comorbidities. Previously, these patients were operated on using the traditional "open" method due to the real risk of side effects from PP. The North American Association of Gastrointestinal Endoscopic Surgeons has formulated the following indications for laparoscopic gas-free surgery: - obstructive pulmonary diseases; - cardiovascular insufficiency; - previous myocardial infarction; - previous surgery on the heart and large vessels; - congenital and acquired heart defects. Every department developing endoscopic technologies should be prepared to perform laparoscopic gas-free surgery. In any case, for patients for whom the anesthesiologist and surgeon jointly formulate contraindications to PP. In conclusion, it should be noted that the statement "minimally invasive surgery = minimally invasive anesthesia" is a misconception. Anesthesia for laparoscopic surgery has its own characteristics, is associated with high risk, and all possible complications and accidents can occur. In our opinion, anesthesia in endosurgery should be administered by specially trained intensive care physicians. Complete mutual understanding between the surgeon and anesthesiologist regarding indications, the choice of surgical technique, and postoperative patient management is of strategic importance.