LECTURE № 2. Preoperative preparation. Features of preoperative preparation for acute surgical diseases accompanied by intoxication

Intoxication is a condition with a characteristic combination of clinical and laboratory signs of pathology of the nervous system, microcirculation system and water-electrolyte metabolism against the background of an infectious and inflammatory process. Diseases of the “acute abdomen”, toxic and toxic-septic forms of acute purulent-inflammatory diseases occur with intoxication.

In emergency surgery, the peculiarity of intoxication is that it occurs against the background of infections caused by staphylococcal or gram-negative bacterial flora. Unlike viral and viral-bacterial infections, in these cases, neurological symptoms do not prevail in the clinical picture.

Most often, hyperthermia and lethargy serve as a background. where a local process unfolds with a generalized reaction of the microcirculation system. Changes in peripheral blood flow are manifested in rheological disorders, intracapillary disorders with intravascular coagulation and activation of the kinin system.

Frequent involvement in the pathological process of the organs of the gastrointestinal tract leads to isotonic or salt-deficient dehydration.

In combination with the pathology of the transmembrane transfer of sodium and potassium, typical of any intoxication, dehydration causes the symptoms of disorders of water and electrolyte metabolism.

An imbalance of water and electrolytes is diagnosed based on the causes of its occurrence, the clinical picture and laboratory data.

An analysis of the causes and ways of fluid loss makes it possible to suggest the nature of disorders of water and electrolyte metabolism.

Loss with vomiting or fluid sequestration in paretically distended bowel loops or in peritoneal exudate leads to salt deficiency or isotonic dehydration; hyperthermia or hyperventilation of any origin - to water deficiency.

Intoxication without clinical signs of dehydration is accompanied by intracellular overhydration and hypokalemia due to intracellular sodium retention and potassium loss.

The diagnosis is confirmed by the results of an objective examination of the child. However, in the course of treatment, one type of dehydration may be replaced by another, which greatly complicates the assessment of the clinical picture.

Therefore, the final diagnosis is based on the results of a laboratory study. Normal values ​​of plasma sodium concentration or hematocrit are by no means proof of the absence of dehydration in a patient, just as not all types of dehydration show the whole triad of symptoms of hemoconcentration.

Hyperproteinemia does not occur in dehydration in children with purulent-inflammatory diseases of the chest and abdominal cavities and in malformations of the gastrointestinal tract, accompanied by malnutrition II-III degrees. The level of total serum protein in this pathology may be normal or be at the lower limit of the age norm.

Confirmation of hemoconcentration in such situations is a high hematocrit. And, conversely, if isotonic or salt-deficient dehydration develops against the background of anemia, an increase in the number of erythrocytes and hematocrit is not expressed, only hyperproteinemia has diagnostic value.

As long as the body is able to maintain stable hemodynamics, we can talk about the stage of dehydration compensation, decompensation occurs with the appearance of circulatory disorders.

With isotonic and hypotonic (salt-deficient) dehydration, signs of decompensation are arterial hypotension, acrocyanosis, hypothermia and oliguria. Decompensation occurs only with dehydration, corresponding to a loss of 10% of body weight.

If the phenomena of intoxication and water-electrolyte imbalance are not reduced before surgery, then during the intervention the sensitivity to blood loss increases, the insufficiency of peripheral blood flow worsens, and the prognosis worsens. Hyperthermia caused by the inflammatory process, water-deficient dehydration, intoxication, increases sensitivity to hypoxia and narcotic drugs.

In this regard, the tasks of preoperative preparation for intoxication are reduced to normalizing the patient's body temperature, improving peripheral blood flow and reducing the degree of dehydration. These tasks are solved by infusion therapy.

The sequence of goals for infusion therapy in this situation should be as follows:

1) providing a volume of liquid corresponding to the degree of water deficiency;

2) reduction of energy deficit with normalization of electrolyte transport through the cell membrane and prevention of intracellular edema with the help of concentrated glucose solutions with insulin;

3) improvement of blood rheology and detoxification using low molecular weight plasma substitutes;

4) normalization of the acid-base state of the blood. Potassium deficiency in the preoperative period, as a rule, is not corrected, since this requires a long period of time.

In addition, at this point it is not always clear how impaired kidney function is and what the danger of a relative overdose of potassium is.

The volume of fluid that the patient needs to eliminate the deficit of water and electrolytes in the preoperative period is calculated taking into account the degree of dehydration and the age of the child. With isotonic or salt-deficient dehydration, the most common in surgical diseases, the calculation is based on the hematocrit value.

The lower part of the nomogram shows the fluid volumes in liters required to correct the water deficit in the preoperative period, depending on the patient's hematocrit. Horizontal scales correspond to the degree of hemoconcentration in percent or the difference between the patient's hematocrit and normal age-related hematocrit.

The volume of liquid is determined as follows: the direct scale of body weight is connected in the upper and lower parts of the nomogram at the point of its intersection with the scale, which corresponds to the difference in hematocrits, and the required volume of liquid in liters is determined.

To determine the daily needs for water and electrolytes, the perpendicular is restored from the age or weight of the patient to the intersection with the wrong curve in the middle part of the nomogram.

From this point, a horizontal line is drawn parallel to the base, and in the corresponding vertical columns, the necessary values ​​\uXNUMXb\uXNUMXbof physiological needs for water and electrolytes, pathological losses with vomiting, intestinal paresis, hyperthermia, dyspnea and the volume of fluid supplemented for detoxification are obtained.

In cases where it is not technically possible to determine the hematocrit or there are no laboratory signs of hemoconcentration, the liquid for the preoperative period is prescribed in the amount of 2-3% of body weight (20-30 ml / kg).

The composition of the injected solutions depends on the state of hemodynamics and the stage of dehydration. In case of circulatory decompensation, the infusion begins with the transfusion of volemic drugs: plasma (10 ml/kg), 10% albumin solution (10 ml/kg) or rheopolyglucin (20 ml/kg). The remaining volume is administered in the form of a 10% glucose solution with insulin (1 unit - 5 g). With normal indicators of central hemodynamics and the predominance of intoxication over dehydration, volemic preparations are replaced with low molecular weight blood substitutes of the hemodez group (10 ml/kg). Infusion in these cases begins with concentrated glucose solutions.

The need for correction of the acid-base state is determined by the results of laboratory control carried out after the introduction of basic solutions.

Therapy should only be initiated when standard blood bicarbonate falls below 15 mmol/L. In clinical practice, 1,3-5% sodium bicarbonate solutions are used to treat metabolic acidosis.

In children older than 2 months, it is advisable to use hypertonic solutions of sodium bicarbonate. The dose is calculated according to the formula: the number of milliliters of a 5% sodium bicarbonate solution is equal to the body weight multiplied by half the base deficiency.

In children under 2 months of age, the administration of hypertonic bicarbonate solutions should be approached with caution. Due to the immaturity of renal osmoregulation, children at this age are more sensitive to disturbances in serum osmotic concentration than to disturbances in the active blood reaction. The dose of 1,3% (saline) sodium bicarbonate solution (in ml) is equal to the newborn's body weight in kilograms multiplied by twice the base deficit.

If laboratory control is not carried out, then alkalizing solutions should be used very carefully. The absolute indications for their use are: insufficiency of peripheral circulation with pallor, marbling of the skin; “white spot” symptom with arterial hypotension; oligoanuria, which occurs as a result of spasm of the afferent arterioles of the kidneys.

Sodium bicarbonate in these cases is prescribed at a dose of 0,12-0,25 g of dry matter or 5-7 ml of a 5% solution per 1 k1 of the child's body weight.

Despite the relative effectiveness of sodium bicarbonate transfusion, success in the treatment of metabolic acidosis primarily depends on measures aimed at restoring impaired blood circulation and kidney function. A significant role in this case is played by transfusions of blood and low molecular weight blood substitutes, ganglion blocking drugs.

Correction of metabolic alkalosis in the preoperative period is not carried out. Respiratory disorders of the acid-base state are eliminated during the treatment of respiratory failure.

It should be noted that all the above calculation formulas are conditional. Therefore, rehydration therapy must be carried out without fail, taking into account the dynamics of laboratory data and the clinical picture.

If, under the influence of treatment, the patient's diuresis increases, the specific gravity of urine decreases, blood pressure stabilizes, and hemoconcentration and hypernatremia disappear, then the amount of fluid is chosen adequately. If signs of dehydration persist, then the volume of injected solutions should be increased.

Infusion therapy, measures to normalize peripheral blood flow and kidney function contribute to the elimination of fever accompanying intoxication. In addition, the patient is prescribed antipyretics and neuroleptics: intramuscularly or intravenously, a 5% solution of amidopyrine (1 ml / kg) with a 50% solution of analgin (0,1 ml / kg) and a 2,5% solution of pipolfen ( 0,1-0,15 ml/kg). If there is no effect after 45-60 minutes, repeat the injection of antipyretics in combination with droperidol (0,25% solution - 0,05-0,1 ml / kg).

Of great importance is the duration of preoperative preparation for this group of patients. In the preoperative period, one should only begin the treatment of intoxication, dehydration, and fever.

It must be taken into account that the desire for complete normalization may unnecessarily delay the preparation for the operation. The task of the preoperative period is to eliminate hypovolemia, improve peripheral blood flow and prevent a further rise in the patient's body temperature. These problems can be solved within 3-4 hours.

Preoperative preparation against the background of traumatic shock

Therapy for traumatic shock

Treatment of trauma shock is one of the most difficult tasks of preoperative preparation in emergency surgery. However, the success of the fight against traumatic shock depends on how early it is started.

In children, the classic picture of traumatic shock is rarely observed. The younger the child, the less pronounced are the differences between the erectile and torpid phases of shock. With the same probability, against the background of clinical signs of circulatory insufficiency, psychomotor agitation or lethargy can be found.

Even with a severe concomitant injury in children, a normal level of blood pressure is maintained for a long time, although the general condition is severe, tachycardia, pallor, sometimes marbling of the skin, cyanosis of the lips and nail beds, cold extremities, and oliguria are expressed.

Often, symptoms of respiratory failure due to circulatory disorders in the pulmonary circulation come to the fore.

The discrepancy between the severity of the injury and the clinical condition of the patient, on the one hand, and "satisfactory" indicators of central hemodynamics, on the other, is apparently the most characteristic feature of traumatic shock at an early age.

In the absence of appropriate treatment, a period of apparent well-being is suddenly replaced by hemodynamic decompensation. The latter in children is much more difficult to treat than in adults. Hence, the younger the child, the more unfavorable prognostic sign in shock should be considered arterial hypotension.

Due to the paucity of clinical symptoms of traumatic shock in childhood, its classification should take into account the nature and severity of the injury, the state of hemodynamics and the effect of the therapy.

This is all the more necessary because, from a practical point of view, it is important that the diagnosis of shock be made before the development of arterial hypotension.

There are four degrees of severity of traumatic shock in children.

Light shock(I). Most often observed in injuries of the musculoskeletal system (damage to more than two bones, excluding fractures of the pelvic bones), blunt abdominal trauma without damage to internal organs.

Within 3 hours from the moment of injury, the patient steadfastly maintains a shock clinic in the stage of centralization of blood circulation.

This stage is characterized by psychomotor agitation or depression, systolic blood pressure within the age norm or increased by 20 units, a decrease in pulse pressure, a tense pulse, tachycardia up to 150 beats / min, sometimes bradycardia.

The skin is pale, cold, cyanotic shade of mucous and nail beds. Central venous pressure (CVP) is often higher than normal. The volume of circulating blood (VCC) is reduced by 25% of the age norm.

Respiratory alkalosis, metabolic acidosis with base deficiency up to 6 mmol/l on average, oliguria. The effect of therapy is manifested within 2 hours.

Moderate shock (II) usually accompanies injuries to the pelvic bones, extensive soft tissue injuries with significant crushing of the tissues, traumatic amputations of one of the limbs, isolated injuries of the abdominal organs, chest trauma with rib fractures and pulmonary contusion.

During the first hour from the moment of injury, there is a rapid transition from the stage of centralization of blood circulation to the transitional stage.

In the transitional stage, the child's behavior is inhibited. Systolic blood pressure is reduced, but not more than 60% of the age norm. Pulse of weak filling, its frequency is more than 150 beats / min of the age norm.

There is shortness of breath. Pallor of the skin, distinct acrocyanosis is pronounced. CVP is below normal. BCC is reduced within 34-45%. Metabolic lactic acidosis with base deficiency on average up to 9,5 mmol / l. An increase in hematocrit. Oliguria.

The effect of therapy occurs within two hours, but there is an undulating course with repeated deterioration.

Severe shock (III) is typical for combined and multiple injuries of the chest and pelvis, for traumatic amputation of several limbs, for bleeding from large vascular trunks. During the first hour from the moment of injury, the stage of decentralization of blood circulation develops.

This stage is manifested in the fall of systolic blood pressure below 60% of the age norm. Diastolic blood pressure is not determined. The pulse is thready, tachycardia with a pulse rate of more than 150 beats / min. The skin is pale cyanotic.

Breathing is frequent, shallow. CVP is below or above normal, depending on the degree of heart failure. BCC is reduced by more than 45% of the norm. respiratory acidosis. Metabolic acidosis with base deficiency in the range of 14-20 mmol / l. An increase in hematocrit. Increased bleeding tissue Anuria.

The effect of therapy occurs two hours after the start of treatment, or it cannot be obtained at all.

Terminal shock (IV) with the clinic of the agonal state. The severity of the course of shock dictates the intensity of therapeutic measures and determines the prognosis.

The stage of hemodynamic disturbance allows assessing the patient's condition at each specific stage of his management and developing a plan for pathogenetically substantiated therapy in the current situation.

The treatment of traumatic shock should be complex with the use of intensive care and timely surgical intervention, which plays the role of the most important anti-shock measure. Indications for surgical intervention in traumatic shock are differentiated depending on the nature of the injury.

Emergency operations for shock of any severity are indicated for abdominal trauma with damage to internal organs and bleeding; with traumatic brain injury with external bleeding or symptoms of cerebral compression; with a spinal injury with symptoms of spinal cord injury; with detachments and injuries of the limbs with a violation of the integrity of large vessels and nerve trunks; with thoracic injury with suspected injury to the heart; intrapleural bleeding; massive crushing of the lung tissue; open valvular or tension pneumothorax; thoracoabdominal wounds.

Do not require urgent surgical intervention closed and open bone fractures, not complicated by massive damage to soft tissues, blood vessels and nerves; fractures of the pelvic bones with the formation of pelvic and retroperitoneal hematomas; penetrating wounds of the chest with pneumothorax or hemothorax amenable to conservative therapy.

Operations in these cases are carried out only after removing the patient from shock.

The complex of intensive care depends on the stage of hemodynamic disturbance, during which anti-shock measures are started.

Stage of centralization of blood circulation:

1) temporary or permanent stop of external bleeding;

2) alcoholone-vocaine (trimecaine) blockade of the fracture area or nerve trunks throughout;

3) immobilization of injured limbs;

4) in the absence of suspicion of an injury to the skull or abdominal organs, the patient may be given narcotic analgesics (omnopon, promedol 1% solution - 0,1 ml / year of life);

5) analgesia by inhalation of methoxyflurane. Neuroleptanalgesia is possible with a reduction in the dose of fentanyl to 0,05 ml/kg of a 0,25% solution. Central anticholinergics (amizil, metamisil) are indicated;

6) Intravenous fluid administration begins with any medium molecular weight or protein blood substitute (polyglucin, polyvinol, plasma, albumin, etc.). In an emergency setting, it is advisable to initially administer a 20% glucose solution with insulin (5 ml/kg), vitamin B6 and cocarboxylase;

7) at the first intravenous puncture, blood sampling is necessary to determine the group and Rh factor of the patient, tests for individual compatibility. After receiving the results of these studies, they switch to a transfusion of the corresponding blood to the patient. The total blood volume of medium molecular and protein blood substitutes under conditions of stopped internal or external bleeding should be at least 15-20 ml / kg. This dose must be transfused within two hours, and at least 1/3 of the volume must be canned blood;

8) it is desirable to control blood substitution according to the dynamics of the CVP (gradual decrease to normal values, i.e. 8 cm H₂O (0,78 kPa) and average hourly diuresis (up to 1 year - 20-25 ml, 3-5 years - 30-40 ml, 6-14 years - 50-60 ml). Finally, the adequacy of the transfusion is assessed by the disappearance of pallor of the skin, cyanosis of the nails and lips, tachycardia against the background of normal blood pressure and red blood values ​​(erythrocytes, hemoglobin, hematocrit);

9) in doubtful cases, when the final effect of infusion therapy is not clear, especially with persistent high central venous pressure and the appearance of signs of congestion in the pulmonary circle, the administration of ganglion-blocking drugs is indicated. A decrease in blood pressure after gangliolytics serves as an indication for further blood transfusion;

10) the question of the operation is decided depending on the indications. If an emergency intervention is necessary, the operation is started simultaneously with the start of blood transfusion, pain relief and treatment of respiratory failure. Transitional stage of hemodynamic disturbance:

1) immobilization of the damaged organ and anesthesia is carried out according to the same principles as in the stage of centralization of blood circulation;

2) infusion therapy begins with any medium-molecular or protein plasma substitute, followed by the fastest possible transition to single-group blood transfusion. Under the condition of stopped bleeding, the total volume of transfused drugs is at least 25-30 ml / kg for two hours, of the total volume, canned blood should be at least half. If the patient does not have chest injuries, then during the first hour of therapy he needs to transfuse sodium bicarbonate (4% solution - 5 ml / kg of body weight);

3) clinical and laboratory signs of the adequacy of blood replacement are the same as in the stage of centralization of blood circulation;

4) after normalization of blood pressure, if there is doubt about the adequacy of transfusion, with signs of stagnation in the pulmonary circulation, reduced hourly diuresis, the administration of gangliolytics is indicated, followed by blood transfusion in case of repeated hypotension;

5) after normalization of central hemodynamics, it is advisable for the patient to transfuse mannitol (10-15% solution - 10 ml / kg);

6) the appointment of a complex of vitamins of group B is mandatory;

7) a single administration of hydrocortisone 5-10 mg/kg is indicated, especially with a tendency to arterial hypotension;

8) antibiotic therapy should be started;

9) tactics in relation to surgical intervention is the same as in the stage of centralization of blood circulation. Stage of decentralization of blood circulation:

1) start of treatment with immediate blood transfusion: initially O (C Rh (-) with subsequent transition to the introduction of blood corresponding to the group and Rh factor of the patient. The transfusion rate should be 30-40 ml / min. If in the first 15-20 minutes, it is not possible to achieve a positive effect from the treatment, then the infusion rate should be doubled by transfusion into the second vein.The introduction of fluid into the second vein begins with a 4% solution of sodium bicarbonate (5 ml / kg) and low molecular weight plasma substitutes (10 ml / kg Then blood is also injected into this vein. The total dose of transfused blood and blood substitutes is dictated by the dynamics of the patient's condition, however, with stopped bleeding, it should be at least 40 ml / kg. 0,5 ml of a 10% solution of calcium chloride per 100 ml of blood) and the advisability of direct blood transfusion, 100-150 ml for every 1000-1500 ml of blood;

2) in the absence of the initial effect of blood transfusion, in parallel with the transition to infusion into the second vein, the patient should be transferred to mechanical ventilation against the background of neuroleptanalgesia or anesthesia with sodium oxybutyrate. During mechanical ventilation, it is desirable to use active exhalation with a negative pressure of 20-30 cm of water. Art. (1,96-2,94 kPa);

3) early introduction (in the first minutes) of hormones of the adrenal cortex (adreson, hydrocortisone - 10-15 mg/kg);

4) after the start of infusion therapy and the transfer (if necessary) of the child to mechanical ventilation, immobilization (without reposition) of the injured limbs is performed using conduction anesthesia or blockade of fracture sites;

5) permanent catheterization of the bladder is required, taking into account hourly diuresis. Monitoring the effectiveness of therapy by the ratio of blood pressure, central venous pressure, hourly diuresis and circulating blood volume, followed by the choice of appropriate treatment;

6) infusion of 4% sodium bicarbonate solution (5 ml / kg) and concentrated glucose with insulin and vitamins (20% glucose solution - 5 ml / kg, 1 unit of insulin per 25 ml of this solution, B vitamins, and also C - 150 mg);

7) tactics regarding surgical intervention is the same as in the previous stages.

Authors: Drozdov A.A., Drozdova M.V.

<< Back: Peculiarities of treatment of children with surgical diseases (General principles of examination and diagnosis. Preoperative preparation)

>> Forward: Acute diseases of the lungs and pleura (Lung malformations. Lobar emphysema. Complicated congenital lung cysts)

We recommend interesting articles Section Lecture notes, cheat sheets:

▪ Medical statistics. Lecture notes

▪ Criminal process. Lecture notes

▪ Russian literature of the XX century in brief. Crib

See other articles Section Lecture notes, cheat sheets.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

Energy from space for Starship 08.05.2024

Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>

Random news from the Archive Lenovo Legion R7000P and R9000P gaming laptops 09.06.2022 The Chinese company Lenovo has introduced new gaming laptops of the Legion series - these are the R7000P and R9000P models. They received powerful AMD processors: a choice of a six-core Ryzen 5 6600H and an eight-core Ryzen 7 6800H are offered. The Nvidia GeForce RTX 7000 and GeForce RTX 3050 Ti mobile cards are responsible for graphics processing in the R3050P model. For the older version of the R9000P, this is the GeForce RTX 3060 or GeForce RTX 3070 Ti for laptops. The displays are based on an IPS matrix and differ in diagonal - 15,6 and 17,3 inches, respectively. The resolution in both cases is 2560 x 1440 pixels with a refresh rate of 165 Hz. There is full coverage of the sRGB color space. The amount of DDR5-4800 RAM is 16 GB, NVMe SSD on the PCI-Express 4.0 bus is used as a drive. The laptops run the Windows 11 operating system. Finally, these models have support for discrete desktop graphics cards. Prices start at $985 for the R7000P and $1270 for the R9000P.

Other interesting news:

▪ New technology increases LED brightness by seven times

▪ New miniature quartz resonators in SMD package

▪ SWAT electric motorcycle

▪ Universal card reader

▪ Heat resistant bioplastic

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the website Electrotechnical materials. Article selection

▪ article Safety and sexual culture. Basics of safe life

▪ article What mistake led to the appearance of a mythical animal on the coat of arms of the Irkutsk region? Detailed answer

▪ article Len sowing. Legends, cultivation, methods of application

▪ article Low-frequency amplifier on the LA4180 chip. Encyclopedia of radio electronics and electrical engineering

▪ article Switching stabilizers on the PWM controller KR1114EU4. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024