decompression sickness
Introduction
Introduction to decompression sickness Decompressionsickness (DCS), commonly known as diver's disease or caisson disease, is caused by improper decompression after operation in a high-pressure environment. The dissolved gas in the body exceeds the supersaturation limit, and bubbles form in the blood vessels and tissues. Systemic disease. In the short-term or decompression process, the patients with acute decompression sickness mainly occur in the femur, tibia and fibula, and the slowly evolving ischemic bone or bone and joint damage is decompressive osteonecrosis. basic knowledge Sickness ratio: 0.0001% Susceptible people: no specific population Mode of infection: non-infectious Complications: hemangioma Acute hemorrhagic necrotic enteritis Colonic atresia Duodenal congenital absence, atresia and stenosis Duodenal vascular compression syndrome
Cause
Decompression sickness
When working underwater, the body is 10m per dive, which is roughly equivalent to increasing the pressure of one atmosphere. The added pressure is called the sum of additional pressure, additional pressure and ground pressure. It is called total pressure or absolute pressure (ATA), and the body is at high pressure. Under the environment, the partial pressure of various gases in the alveoli is increased, and it is immediately balanced with the partial pressure of various gases in the compressed air. Because the partial pressure of the gas in the alveoli is higher than the pressure of the gas in the blood, the gas follows the law of Boyle. Correspondingly, the amount of dissolved gas in the blood is increased, and then transported to various tissues through the blood circulation. Most of the oxygen and carbon dioxide are quickly absorbed by hemoglobin and plasma components, and only a small amount is physically separated from the body fluid, and the nitrogen is in the body fluid. The amount of dissolved in the air is proportional to the height of the gas pressure and the length of the residence time. Because nitrogen has different solubility in various tissues, the distribution in the tissue is not equal. The solubility of nitrogen in fat is about 5 times that in the blood, so most of the nitrogen is concentrated. In fat and nerve tissue.
When the human body gradually shifts from normal to high pressure, the excess nitrogen in the body is released from the tissue and enters the blood; and the alveoli gradually and slowly excreted from the body without adverse consequences. When the decompression is too fast, the total external pressure is excessive. It is impossible to continue to maintain the dissolved state, so it is free to the gas phase in a few seconds to several minutes, and accumulates in the form of bubbles in the tissues and blood; the faster the decompression, the faster the bubble generation, the more the accumulation, the nitrogen can be used for a long time. Bubble state exists, in tissues with more fat and less blood circulation, such as adipose tissue, peripheral nerve myelin, central nervous white matter, connective tissue of tendon and joint capsule, etc., denitrification is difficult, in addition to intravascular bubbles, nitrogen Bubbles often accumulate outside the walls of blood vessels, squeezing surrounding tissues and blood vessels, and stimulating nerve endings, even pressing, tearing tissue, causing local bleeding and other symptoms. In tissues with less fat and smooth blood flow, nitrogen bubbles are more in blood vessels. Forming embolism, obstructing blood circulation, air bubbles and causing vasospasm, leading to distal tissue ischemia, edema and hemorrhage, according to the embolization site and its The degree of organization and nutritional disorders long time since temporarily, can produce a range of symptoms.
In addition, due to the continuous formation of air bubbles inside and outside the blood vessels, causing tissue hypoxia and damage, the cells release potassium ions, peptides, histamines and proteolytic enzymes, which in turn stimulate the production of histamine and serotonin. It mainly acts on the microcirculatory system, causing vascular smooth muscle paralysis, microcirculatory vascular obstruction, etc., thereby reducing the desaturation rate of nitrogen in tissues and body fluids. Therefore, in the pathogenesis of decompression sickness, bubble formation is the primary factor; The role of the air interface can still cause a series of pathophysiological reactions, which makes the clinical manifestations of decompression sickness complicated.
The special role of the bubbles in the bones is that the bones are an inextensible tissue. The long bones in the long bones such as the femur, tibia, and tibia have high fat content, and the blood flow is very slow. When decompressed, a large amount of air bubbles will be generated to directly compress the blood vessels in the bone; There are also air embolism and thrombus in the vascular nutrient vessels, which can easily cause local infarction, and finally slowly cause aseptic ischemic osteonecrosis, also known as dysbaric osteonecrosis or aseptic osteonecrosis. In addition to the special role of bubbles in the bone, there are also a combination of fat embolism, platelet aggregation, gas induced osmotic pressure changes, autoimmune and other effects.
Prevention
Decompression sickness prevention
1. For divers, especially new divers, medical knowledge should be educated to enable divers to understand the causes and prevention methods of decompression sickness.
2, develop good hygiene habits, establish a reasonable living system, rest before work to prevent excessive fatigue; do not drink alcohol and drink less water, work should be protected from cold and damp, work should immediately take off wet work clothes, drink hot Tea, wash the hot water bath, rest in the warm room for more than half an hour to promote blood circulation, so that the excess nitrogen in the body is accelerated.
3, daily should ensure high calorie (generally about 15072 ~ 16747KJ per day), high protein, medium fat diet, and appropriate increase of various vitamins, recent domestic useful rabbit experiments, showing that vitamin E has a certain prevention or reduce experimental The effect of decompression sickness may be due to the prevention or reduction of the release of biologically active substances such as serotonin in the stored particles in the platelets, so that intravascular coagulation does not occur.
4, before the diver employment, regular and pre-dive physical examination, bones and joints, especially the four limbs and large joints should be X-ray film every year, until the end of high-pressure operation four years, all suffering from hearing organs, cardiovascular system, digestion The system, respiratory system, nervous system and skin diseases are not suitable for high-pressure environment work. After serious illness, those with physical weakness, long-term fractures, alcoholics and obesity are also listed as employment taboos.
Complication
Decompression sickness complications Complications hemangioma acute hemorrhagic necrotic enteritis colonic atresia duodenal congenital absence, atresia and stenosis duodenal vascular compression syndrome
Thrombosis, hemangioma, hemorrhagic necrotic intestine, colon atresia, congenital absence of duodenum, atresia and stenosis, duodenal vascular compression syndrome.
Symptom
Symptoms of decompression sickness Common symptoms Joint soreness Itching Muscle soreness Joint pain Subcutaneous tissue Edema Acupoint subcutaneous hematoma
There are diving operations, caissons, special high-altitude flight history, and failure to comply with decompression regulations, and those with nitrogen bubble compression or vascular embolism symptoms and signs should be considered as decompression sickness. Foreign scholars divide decompression sickness into light. Grades (type I) and heavy grades (type II), where central nervous system symptoms or circulation, respiratory system involvement are all heavy, in fact about 1/3 of patients are type I and type II composite cases.
The Ministry of Health of China divides acute decompression sickness into three levels: light, medium and heavy:
1 mild manifestations of skin symptoms such as itching, papules, marble-like markings, subcutaneous hemorrhage, edema, etc.
2 Moderately occurs mainly in muscle joint pain in and around the large joints of the extremities.
3 severely one of the nervous system, circulatory system, respiratory system and digestive system disorders.
Examine
Decompression sickness check
Doppler bubble detectors can be used to detect flow bubbles in the great vessels of the precordial area before symptoms occur, called "ultrasound monitoring." Magnetic resonance examination revealed the site of spinal cord damage.
The routine diagnosis of decompressive osteonecrosis was examined by X-ray examination and divided into three phases according to the X-ray changes of the bone. Can also use 99m for scintigraphy or gamma photography, early detection of some lesions not found on X-ray films, but can not show cystic changes and calcification lesions.
Diagnosis
Diagnostic diagnosis of decompression sickness
diagnosis
Diagnosis can be performed based on clinical manifestations and examinations.
Differential diagnosis
The pain symptoms of this disease must be differentiated from general trauma and inflammation. Other diving diseases such as pulmonary barotrauma, acute hypoxia, oxygen poisoning and nitrogen anesthesia must be differentiated from diving decompression sickness.
