What Is Acute Dehydration?

Acute dehydration is a pathophysiological syndrome caused by a decrease in body fluid volume, mainly extracellular fluid volume, caused by some pathological factors. Common pediatric emergencies such as diarrhea and vomiting can cause dehydration in children.

Acute dehydration

Chinese name: Acute dehydration
Foreign name: Acute dehydration

Main: Caused by a decrease in extracellular fluid volume
By: Some pathological factors cause fluid volume

Body fluids are an important part of the human body, and maintaining the physiological balance of body fluids is one of the important conditions for maintaining normal physiological activities of the human body. Water in body fluids,

1.1 clinical manifestations

1.1.1 Clinical manifestations of primary disease Dehydration is a pathophysiological syndrome caused by a decrease in fluid loss. Pay attention to the clinical manifestations of primary disease to help find the cause of dehydration and to cure the disease. Different primary diseases have their own clinical manifestations, such as the main manifestation of enteritis is diarrhea, and the main manifestation of gastritis is vomiting. The primary cause of dehydration can directly affect the nature of children's water and electrolyte disorders, such as the loss of intestinal alkaline fluids during diarrhea, and the acidic fluids of the stomach during vomiting.

1.1.2 Clinical manifestations of dehydration Dehydration can cause changes in the neurological and mental state of the child, causing the child to develop anterior ridges and depressions in the eye sockets, dryness and poor elasticity of the skin and mucous membranes. In severe cases, it can cause children with less urine, poor peripheral circulation and Metabolic acidosis. The clinical manifestations of dehydration of different natures and different degrees are not the same. Clinicians need to make comprehensive clinical analysis and judgement to accurately and comprehensively evaluate the condition in order to perform effective and timely treatment.

1.2 Clinical evaluation

1.2.1 Clinical evaluation of the degree of dehydration

The degree of dehydration is often evaluated as a percentage of body fluid lost. Patients often have a history of fluid loss and signs of dehydration. If the patient does not have a recent weight record, the percentage of weight loss can often be estimated by physical examination and medical history. Generally based on comprehensive analysis of clinical manifestations such as anterior condyle, depression of the eye socket, skin elasticity, circulation and urine output, the degree of dehydration is often divided into three degrees (see Appendix 1).

Schedule 1 Clinical evaluation of the degree of dehydration

Dehydrated body weight reduces cumulative loss of nerves and metatarsal and oral skin surrounding metabolism

Degree (%) (ml / kg) Mental state Orbital depression Mucosal elastic circulation Urinary acidosis

Mild dehydration 5 50 slightly changed slightly slightly dry but no obvious change slightly less inconspicuous

Moderate dehydration 5 10 50 100 Depression or irritability Significantly dry Decreased coldness of limbs, markedly reduced significantly

Slightly faster pulse

Severe dehydration> 10 100 120 Extremely debilitating, extremely obvious, extremely dry, extremely poor limbs, cold, little or no serious

Drowsiness or even coma with closed eyes and lower blood pressure,

shock

Mild dehydration: the child has a weight loss of 3 to 5% or a body fluid equivalent to 30 to 50 ml / kg. The clinical manifestations are slightly inferior and slightly irritable; the skin is slightly dry during the physical examination, the elasticity is acceptable, and the eye sockets and anterior condyles are slightly sunken; tears occur when crying, the lips and mucous membranes are slightly dry, and urine output is slightly reduced.

Moderate dehydration: Children have a weight loss of 5 to 10% or the equivalent of 50 to 100 ml / kg of body fluid loss. The clinical manifestations are apathetic or irritable; pale, dry, and poorly elastic skin, obvious depressions in the eye sockets and anterior condyles, less tears when crying, and dry lips and mucous membranes; limbs are slightly cooler and urine output is significantly reduced.

Severe dehydration: more than 10% of the children's weight loss or equivalent body fluid loss of 100 ~ 120ml / kg. The clinical manifestations are that the child is seriously ill, with extremely debilitating spirit, indifferent expression, lethargy, and even coma; the skin is gray or patterned, and the elasticity is extremely poor; the eye sockets and anterior condyles are deeply sunken, the eyes are closed, the eyes are gazed, and there is no tears when crying ; Lip and mucous membranes are extremely dry. Shock symptoms can occur due to a significant reduction in blood volume, such as dull heart sounds, a rapid pulse, decreased blood pressure, cold limbs, little or no urine.

1.2.2 Clinical evaluation of dehydration properties

Schedule 2 Clinical Evaluation of Dehydration Properties

Isotonic dehydration

Serum sodium (mmol / L) 130 150 <130> 150

Cause of diarrhea, malnutrition with diarrhea, high fever, excessive sweating, high temperature environment,

Long-term diarrhea, intake of infantile diarrhea, drinking less water,

Liquid with little or no electrolyte, oral hypertonic saline

With diuretics

Water and electrolyte loss are proportional to electrolyte loss> water loss> water loss> electrolyte

Loss of water transfer homeostasis from extracellular to intracellular From intracellular to extracellular

Extracellular fluid and

Significant reduction in plasma reduction Less significant

Peripheral circulation disorder is relatively heavy and relatively light depending on the degree of dehydration

Intracellular fluid increases near normal and decreases

Nervous symptoms are not obvious, lethargy, even coma, restlessness, and even convulsions

(Brain cell edema) (brain cell shrinkage)

Other symptoms generally show early signs of dehydration, mild signs of dehydration, but high fever,

Heavier but less thirsty and thirsty, increased muscle tone

During dehydration, both water and electrolytes are lost, but the proportion of water and electrolytes (mainly sodium) lost in dehydration caused by different causes can be different, resulting in different changes in body fluid osmotic pressure. The evaluation of the dehydration property is mainly based on the changes in the osmotic pressure of the existing body fluids, which reflects the relative loss of water and electrolytes. It is often evaluated clinically based on the detection levels of serum sodium and plasma osmotic pressure. Serum electrolytes and plasma osmotic pressure are often interrelated because osmotic pressure depends to a large extent on the level of serum cations, that is, sodium ions. The nature of dehydration can be divided into three types: isotonic dehydration, hypotonic dehydration and hypertonic dehydration. Among them, isotonic dehydration is the most common, followed by hypotonic dehydration, and hypertonic dehydration is rare. Clinically, the determination of serum sodium, the patient's medical history and clinical manifestations are used to judge the nature of dehydration (see Appendix 2).

Isotonic dehydration: The serum sodium ion concentration of the child is between 130 and 150 mmol / L. At this time, there is no osmotic pressure gradient inside and outside the cell, and the content of the cell remains unchanged. The clinical manifestations vary depending on the severity of dehydration, The extent depends on the amount of extracellular volume lost.

Hypotonic dehydration: The serum sodium ion concentration of the child is less than 130mmol / L. At this time, water enters the cell from outside the cell, and the circulation capacity is further reduced due to the loss of circulating capacity to the cell. In severe cases, blood pressure may drop and shock may occur. As blood pressure drops, visceral blood vessels undergo reflex contraction, renal blood flow decreases, glomerular filtration rate decreases, urine output decreases, and azotemia occurs. Another consequence of the decreased glomerular filtration rate is the reduction of sodium ions entering the renal tubules, so that almost all of sodium is reabsorbed. In addition, the decrease in plasma volume causes increased secretion of aldosterone, and the absorption of sodium is more complete, so sodium in urine 2. Extremely reduced chloride ions and decreased specific gravity of urine. If you continue to add hypotonic fluids, you can have serious consequences such as water poisoning and brain edema. Because the degree of reduction of extracellular fluid during hypotonic dehydration is relatively obvious compared with the other two types of dehydration, the clinical manifestations are more serious. There may be no symptoms of thirst at the beginning. In addition to general dehydration such as reduced skin elasticity, depression of the eye socket and anterior condyle, there are many shock symptoms such as cold limbs, flowering of the skin, decreased blood pressure, and decreased urine output. Due to reduced circulating blood flow and tissue hypoxia, brain cell edema can occur in those with severe hyponatremia, so there are many neurological symptoms such as lethargy, and even convulsions and coma. When accompanied by acidosis, there is often deep breathing; weakness, abdominal distension, intestinal obstruction or arrhythmia may occur with hypokalemia; muscle convulsions, convulsions, and abnormal electrocardiograms may occur when accompanied with hypocalcemia and hypomagnesemia.

In hypertonic dehydration: The serum sodium ion concentration of the child is greater than 150mmol / L. At this time, water is transferred from the inside of the cell to the outside of the cell to balance the osmotic pressure inside and outside the cell. As a result, the content of the cell is reduced. At this time, the extracellular fluid was supplemented by the intracellular fluid, so the clinical signs of dehydration were not obvious, the skin was often warm, and there was a kneading feeling; the nervous system could show drowsiness, but the muscle tension was high and the reflection was active. Because the extracellular sodium concentration is too high and the osmotic pressure is increased, the body's antidiuretic hormone increases, and the kidneys absorb more water, resulting in a decrease in urine output. After the osmotic pressure of the extracellular fluid increases, water leaks out of the cells to regulate the osmotic pressure inside and outside the cells, resulting in a decrease in the intracellular fluid. Because the reduction of extracellular fluid is not serious, circulatory failure and reduction of glomerular filtration rate are lighter than the other two types of dehydration. Due to lack of intracellular water, children often have severe thirst, high fever, irritability, increased muscle tone, and even seizures. As the burden on the kidneys increases significantly after dehydration, it is necessary to absorb water as much as possible while removing waste from the body. If dehydration continues to increase, azotemia will eventually occur.

1.2.3 Clinical evaluation of metabolic acidosis

The blood pH value of normal children is the same as that of adults, which are both 7.4, but the range is slightly wider, that is, 7.35 to 7.45, the pH value is less than 7.35 in humans is acidosis, and acidosis caused by dehydration is mostly metabolic acidosis. The body's adjustment of PH at a more stable level depends on two mechanisms: physical, chemical or buffer mechanism, which can prevent excessive acid or alkali loss. Physiological mechanism, mainly including organs such as kidney and lung, which directly participate in the buffer regulation mechanism, so that the buffer mechanism can play a more effective role. The buffer system for blood and other body fluids mainly includes two aspects: carbonic acid, bicarbonate system and non-bicarbonate system. In the blood non-bicarbonate buffer system, mainly hemoglobin, organic and inorganic phosphorus, and plasma proteins account for a small part. There is almost no non-bicarbonate buffer system in the interstitial fluid. In the intracellular fluid, carbonic acid, bicarbonate and non-carbonate buffer systems all work. The latter is mainly composed of organic phosphoprotein and other components.

The causes of metabolic acidosis are due to: vomiting and diarrhea lose a large amount of alkaline substances, eat less, lack calories, intestinal malabsorption, and the body does not get normal energy supply leading to increased fat breakdown and a large number of ketone bodies. Blood volume decreases during dehydration, blood is concentrated, blood flow is slow, and lactic acid accumulates due to tissue hypoxia. Dehydration makes renal blood flow inadequate, and its low acid and sodium retention capacity causes acidic metabolites to stay in the body. Patients may experience symptoms such as lack of energy, rosy lips, deep breathing, and exhaled breath containing ketone smell, but the symptoms of small infants can be very atypical.

1.2.4 Clinical evaluation of abnormal potassium metabolism

1.2.4.1 Hypokalemia

The potassium in the human body is mainly present in the cell, and the normal serum potassium is maintained at 3.5 to 5.0 mmol / L, which plays an important role in regulating various functions of the cell. When the serum potassium concentration is lower than 3.5mmol / L, it is called hypokalemia. Gastrointestinal fluid contains more potassium (about 17.9 ± 11.8 mmol / L in the stool during diarrhea), and vomiting and diarrhea result in the loss of a large amount of potassium; less eating, insufficient ingestion, and the potassium-retaining function of the kidney is better than sodium Poor, a certain amount of potassium continues to be excreted during potassium deficiency, so there is often a potassium deficiency in the body during dehydration. However, before the dehydration is not corrected, due to blood concentration, potassium transfer from the cell to the outside during acidosis, and decreased urine output due to less urine, the total potassium in the body is reduced, but serum potassium is mostly normal. As dehydration and acidosis are corrected, potassium excretion increases after urination, potassium loss in the stool and potassium consumption during glucose input to synthesize glycogen rapidly decrease blood potassium, followed by varying degrees of potassium deficiency symptoms, such as loss of energy , Weakness, bloating, arrhythmia, etc. The ECG showed that the ST segment was reduced, the T wave was flat or inverted, the QT interval was extended, and U waves appeared, and U waves were higher than T waves in the same lead.

The main causes of hypokalemia are: insufficient potassium intake; excessive loss of the digestive tract; such as vomiting, diarrhea, various drainages or frequent enema without timely potassium supplementation; excessive kidney excretion; For example, potassium caused by acidosis is released from the cells, and then is excreted by the kidneys in large quantities. Clinically, children with severe dehydration and acidosis often have serum potassium in the normal range, and the symptoms of potassium deficiency are not obvious. When a potassium-free solution is input, potassium is excreted with an increase in urine volume as the plasma is diluted; potassium is transferred into the cells after acidosis is corrected; potassium can be consumed during glycogen synthesis. Due to the above reasons, serum potassium decreases and symptoms of hypokalemia appear. The abnormal distribution of potassium in the body: such as in familial periodic paralysis, the patient produces hypokalemia due to the rapid migration of potassium from the extracellular fluid into the cells. Alkali poisoning for various reasons.

The clinical manifestation of hypokalemia is not only determined by the concentration of potassium in the blood, but more importantly the rate of potassium deficiency. When serum potassium decreased by 1 mmol / L, total potassium in the body decreased by 10-30%. At this time, most children can tolerate it; those with slow onset may have severe potassium deficiency, but the clinical symptoms may not be severe. Symptoms usually occur when serum potassium is below 3 mmol / L. Including: Neuromuscular: neuromuscular excitability decreases, manifested by changes in skeletal muscle, smooth muscle and cardiac function, such as muscle weakness, severe respiratory muscle paralysis or paralytic intestinal obstruction, gastric dilatation in severe cases; knee reflex, abdominal wall reflex Or disappear. Cardiovascular system: cardiac arrhythmia, decreased myocardial contractility, decreased blood pressure, and even heart failure; ECG manifests as low T-wave width, U-wave, Q interval prolongation, T-wave inversion, and ST-segment decline. Renal function impairment: Low potassium reduces renal condensing function, polyuria appears, and severe cases have alkalosis symptoms. Long-term hypokalemia can cause nephron sclerosis and interstitial fibrosis, which is pathologically difficult to distinguish from chronic pyelonephritis. In addition, chronic hypokalemia can reduce growth hormone secretion.

1.2.4.2 Hyperkalemia

When the serum potassium concentration 5.5mmol / L is called hyperkalemia, improper fluid replacement during dehydration can cause iatrogenic hyperkalemia, or even life-threatening. Therefore, seeing potassium supplementation in urine is an important principle for fluid replacement.

The main causes of hyperkalemia are: renal failure, renal tubular acidosis, hypoadrenal cortical function, etc., reduce potassium excretion; shock, severe hemolysis, and severe crush injury, etc., make potassium distribution abnormal; due to input The solution containing potassium is too fast or the concentration is too high.

Clinical manifestations of hyperkalemia: Electrocardiogram abnormalities and cardiac rhythm disorders: Heart rate slows down and is irregular during hyperkalemia, and premature ventricular contractions and ventricular fibrillation may occur, and even cardiac arrest may occur. Electrocardiograms can show towering T waves, P waves disappearing or QRS complexes widening, ventricular fibrillation, and cardiac arrest. Electrocardiogram abnormalities are the most important basis for determining whether children need anti-hyperkalemia treatment. Nerve and muscle symptoms: Children with hyperkalemia are debilitated, drowsiness, hand and foot sensation abnormality, tendon reflexes are weakened or disappeared, flaccid paralysis, urinary retention and even respiratory paralysis occur in severe cases.

1.3 Diagnosis and differential diagnosis

1.3.1 Diagnosis

The main basis of dehydration is the presence of the cause of dehydration in children and the clinical manifestations of dehydration. The diagnosis of dehydration includes: diagnosis of the primary disease; diagnosis of the degree of dehydration; diagnosis of the nature of dehydration; diagnosis of the disturbance of the hydroelectric medium, such as diagnosis of acidosis, hyperkalemia, hypokalemia, etc.

A detailed medical history often provides information on the nature and extent of dehydration. Therefore, the patient's intake and discharge, weight change, frequency and frequency of urination, general conditions, and changes in the child's temperament should be inquired in detail. When the child has diarrhea for several days, the intake of water is normal and the intake of sodium and salt is very low, it is often manifested as hypotonic dehydration; when the intake of water is few for a few days with high fever, the formula is incorrectly formulated as high Hypernatremia may occur when infiltrating or using hypertonic fluids; hyponatremia may occur when diuretics are used and there is a lack of salt in the kidneys and ingestion is insufficient. However, hypertonic dehydration may also occur when children have primary or secondary nephrogenic diabetes insipidus and water intake is restricted. Generally, the stool of diarrhea is hypotonic. With the oral supplementation of the hypotonic liquid, the final dehydration is isotonic.

1.3.2 Differential diagnosis

The differential diagnosis of dehydration includes: the differential diagnosis of the primary disease; the differential diagnosis of the degree of dehydration; the differential diagnosis of the dehydration nature; the differential diagnosis of hydroelectric medium disorders, such as acidosis, hyperkalemia, hypokalemia, etc. Differential diagnosis.

The clinical signs of mild, moderate, and severe dehydration often overlap, and fluid loss per unit weight is sometimes difficult to accurately estimate. Clinical diagnosis can be summarized by "mild to moderate dehydration" or "moderate to severe dehydration." It should be noted that in the presence of severe malnutrition, the degree of dehydration is often overestimated. Orbital depression is often found by parents, and its recovery is often one of the earliest signs of improvement after fluid replacement.

2 Clinical treatment and evaluation

2.1 Etiology treatment purpose refers to controlling the primary disease causing dehydration, and taking different treatment measures for different causes.

2.2 Fluid therapy

2.2.1 Principles of fluid therapy

Fluid therapy is an important part of pediatric medicine. Its purpose is to maintain or restore normal body fluid volume and composition to ensure normal physiological functions. The general treatment principles of fluid therapy can be summarized as: regular, qualitative, quantitative, and fixed speed; save lives first, and then eliminate the cause; salt first, sugar, fast first, then full, first thick, then light, and not more; See potassium supplementation in urine and calcium supplementation in case of surprise, adjust in time; observe closely, handle complications in time, and correct acidosis and water and electrolyte disorders.

In general, the kidney, lung, cardiovascular and endocrine systems have a strong role in regulating fluid balance in the body, so if the fluid replacement components and amounts are basically suitable, the body can fully adjust to restore the normal balance of body fluids; There is insufficiency of the device, the components of the liquid should be selected more strictly, the amount of fluid replacement and the speed should be selected according to its pathophysiological characteristics, and adjusted according to changes in the condition. Fluid therapy includes supplementary physiological needs, cumulative losses and continued losses. Each of these sections can be calculated and supplemented independently. Because the cause and nature of body fluid imbalance are very complicated, it is necessary to comprehensively grasp the medical history, physical examination and experimental data and individual differences of children when formulating the fluid replacement plan, analyze the different needs of the three parts of fluid, and determine a reasonable and correct infusion volume, speed, and composition And sequence.

2.2.2 Supplement of physiological requirements

Physiological requirements involve heat, water, and electrolytes. Maintenance fluid volume and electrolyte are directly related to metabolic rate. Changes in metabolic rate can affect the production of endogenous water through oxidation of carbohydrates, fats and proteins, and the discharge of solutes from the kidney can affect the discharge of water. 25% of water is lost through insignificant dehydration. Energy production will inevitably affect water loss. Therefore, the estimation of normal physiological requirements can be calculated based on energy requirements. Generally, 100-150ml of water is required for each 100kcal of metabolism; The younger you are, the more water you need, so you can use a simple calculation table. Physiological needs depend on urine output, stool loss, and insignificant dehydration. Physiological requirements should be supplemented orally as much as possible. Those who cannot orally can inject intravenously 1/4 to 1/5 sodium-containing solutions, while giving physiological requirements potassium. Children with fever and rapid breathing should increase fluid intake appropriately; those with malnutrition should pay attention to energy and protein supplementation, and use partial or total intravenous nutrition if necessary.

Supplementary physiological needs should be considered in three aspects, including heat, fluid volume and electrolytes. Calories: Supply with glucose solution. The first day of fluid replacement should provide as much calories as necessary for basal metabolism. Infants and young children 230-250KJ / (50-60kcal / kg) daily, sufficient calories can reduce tissue consumption such as fat and protein. Fluid volume: The amount of fluid ingested daily should supply the involuntary dehydration volume of the lungs and the skin or the amount of water lost by sweat, urine, stool, etc. The insignificant dehydration accounts for about 1/3 of the fluid loss. Increased during fever. In the case of fasting, in order to meet the needs of basal metabolism, the daily fluid supply is about 70-100ml / . Electrolyte: Physiologically required electrolytes should be supplemented orally as far as possible. Those who cannot orally take less than 1-4 to 1/5 sodium-containing solutions can be infused intravenously. Children with fever, rapid breathing, and convulsions should appropriately increase the amount of water. Children with long-term infusion or with malnutrition should pay more attention to calories and protein supplements. Partial or total intravenous nutritional fluids can be used if necessary.

2.2.3 Supplementary Cumulative Loss

That is, the total amount of water and electrolytes that the child already had before the supplementation was supplemented, and the supplementation was given quantitatively, regularly and at a fixed rate according to the degree and nature of dehydration. Quantitative: The amount of fluid replacement is determined according to the degree of dehydration. Mild dehydration is about 30-50ml / ; moderate dehydration is about 50-100ml / ; severe dehydration is about 100 ~ 150ml / kg. First give the total amount of 1/2 to 2/3. The body fluid composition of preschool and school age children is close to that of adults. The amount of fluid replacement should be reduced by 1/4 to 1/3 as appropriate. Qualitative: The type of fluid replacement is determined according to the nature of dehydration. Usually for hypotonic dehydration, 2/3 sheets of sodium-containing solution should be replenished; for isotonic dehydration, 1/2 sheet of sodium-containing solution, and for hypertonic dehydration, 1/3 l / 5 sheets of sodium-containing solution, If you have difficulty in dehydration, you can add isotonic dehydration first. Constant speed: the infusion speed. The rate of fluid replenishment depends on the degree of dehydration. For children with severe dehydration accompanied by poor circulation and shock, begin to quickly enter isotonic sodium-containing solution (normal saline or 2: 1 solution), and press 20ml / (the total amount does not exceed 300m1) in the vein within 30 minutes to 1 hour. Enter to quickly improve circulating blood volume and renal function, and the remaining cumulative loss is completed within 8-12 hours. Potassium supplements should be promptly given after the circulation improves. For children with hypertonic dehydration, hypernatremia needs to be corrected slowly because the osmotic pressure of the nerve cell fluid is high, and a large amount of water quickly entering the cells can cause brain cell edema and even convulsions.

2.2.4 Replenishment of Continued Loss

After starting to supplement the cumulative loss, most of the losses such as diarrhea, vomiting, and gastrointestinal drainage continue to exist, so that body fluids continue to be lost, and if not supplemented, it will become a new cumulative loss. The amount of this loss varies depending on the original disease, and it can change daily. This must be evaluated and supplemented with a similar solution based on the actual loss.

Diarrhea in children with diarrhea is difficult to estimate. It can be evaluated based on the number of stools and dehydration recovery, and the amount of fluid can be increased or decreased. Generally, it is calculated at 10 40ml / kg per day. Intravenous drip within hours. Patients with mild non-vomiting can use oral rehydration. The potassium content of the digestive tract is high, and it should be supplemented in time when it is lost.

2.2.5 Correction of Acidosis

Application of basic drugs, commonly used is sodium bicarbonate, can be taken orally or intravenously to correct acidosis. At the same time, find out the primary disease and remove the cause in time. It should not be used in shock, hypoxia, liver insufficiency, neonatal period or lactic acid retention.

If the blood gas is measured unconditionally, it can be temporarily given 1.4% NaHC03 or 1.87% sodium lactate 1ml / kg, and can be repeated for 2 to 4 hours if necessary; if the blood gas analysis result is known, it can be calculated according to the following formula:

Ml of 5% sodium bicarbonate = (18-measured carbon dioxide binding force mmol / L) × 1.0 × weight ;

11.2 (ml of sodium lactate = (18-measured carbon dioxide binding force mmol / L) × 0.6 × body weight)

Generally used isotonic sodium-containing solution (3.5 times diluted with 5% NaHC03 is 1.4% isotonic solution; 11.2% sodium lactate diluted 6 times is 1.87% isotonic solution). Critical illness or severely restricted water intake can reduce the dilution factor or no dilution; due to the body's compensation regulation function, most children with acidosis can be corrected without the need to replenish the full amount of alkaline drugs, which can generally be replenished for the first time. Calculate the amount, closely observe the condition, and adjust the dose at any time to avoid excessive alkali supplementation and alkalosis.

2.2.5 Correction of electrolyte disorders

In the process of acid correction, potassium ions into human cells can easily reduce the serum potassium concentration and hypokalemia, so it should be paid attention to supplement potassium in time. Mild hypokalemia can be more potassium-rich foods or daily oral potassium chloride 3 ~ 4ml / (20 ~ 30mg / kg). Severe hypokalemia can be supplemented intravenously with potassium at a concentration of 0.2% and no more than 0.3%. The total daily amount can reach 30 to 45 mg / kg, about 10% potassium chloride 1 to 2 ml / ml. Infusion, the infusion time should not be less than 8 hours. During the treatment, the clinical symptoms should be closely observed, and the concentration and speed of the potassium-containing solution should be adjusted at any time. Those with severe dehydration and renal dysfunction that affect potassium excretion need to be expanded first to improve circulation and renal function. Potassium supplementation is required after urine is excreted. Due to the slow recovery of intracellular potassium, the treatment of hypokalemia should be continued for 4 to 6 days, and the treatment time should be longer for those with severe or extrarenal potassium loss.

After correction of acidosis, free calcium is reduced and those who have convulsions should pay attention to calcium supplementation. 5 to 10 ml of 10% calcium gluconate can be added to 10 to 20 ml of 10% glucose solution. After dilution, a slow bolus injection will be repeated, if necessary. If hypomagnesemia is considered when calcium is not effective, 25% magnesium sulfate can be used at 0.1 to 0.2 ml / each time. Deep intramuscular injection is used every 6 hours, and 3 to 4 times in a row.

The water, electrolyte and acid-base imbalance caused by various diseases have slightly different requirements for the above three parts. Among them, the physiological requirements are the same, and the latter two are determined by the disease. For example, those who cannot eat due to common diseases need to supplement their physiology. Requirement, gastrointestinal drainage or intestinal fistula after surgery should be supplemented with physiological requirements and abnormal loss, while infant diarrhea should be supplemented in all three.

2.3 Fluid therapy for common pediatric diseases

2.3.1 Fluid therapy for malnutrition with diarrhea

Extracellular fluid is generally hypotonic during malnutrition, and hypotonic dehydration, acidosis, hypokalemia, and hypocalcemia are prone to occur during diarrhea. Due to low subcutaneous fat during malnutrition, it should be avoided when estimating the degree of dehydration. The amount of fluid replacement should be reduced by 1/3 of the total amount and slowly infused with 2/3 sodium-containing solution. In order to replenish calories and prevent hypoglycemia, 10% to 15% glucose solution can be infused intravenously, and potassium, calcium, magnesium, etc. can be added in time.

2.3.2 Fluid therapy in severe pneumonia

Children with pneumonia are often accompanied by high fever, sweating, accelerated breathing, increased heat energy consumption and insufficient intake, and are prone to hypertonic dehydration and mixed acidosis. Pay attention to the infusion: Total fluid volume to ensure sufficient fluid volume And the need of heat, in order to avoid dehydration and acidosis, the principle is to try to take it orally as much as possible, and those who can not take it by intravenous supplementation, the daily fluid volume is about 60 ~ 80ml / . Children with pneumonia are often accompanied by hypertonic dehydration. One third of sodium-containing fluid can be added. If dehydration and metabolic acidosis occur with diarrhea, rehydration can be performed according to diarrhea, but the total amount and tension should be relatively reduced. Infusion It should be slow to avoid burdening the heart. In the case of acidosis, emphasis should be placed on correcting hypoxia and improving the ventilation function of the lungs. Alkaline fluids are generally not required. Only when the acidosis is too severe (PH <7.20) or combined with metabolic acidosis can sodium bicarbonate be used. But the amount should not be too much.

2.4 Fluid therapy for newborns

The newborn's liver and kidney function is immature, and the ability to regulate water, electrolyte and acid-base balance is poor. Therefore, water-electrolyte balance disorders are prone to occur, but clinical symptoms are often not obvious. Therefore, you should inquire and record the daily fluid intake and volume, and observe closely in time Treatment so as not to delay rescue opportunities. Caution should be taken when rehydration: newborns within 10 days of birth generally do not supplement potassium. If obvious potassium deficiency requires intravenous supplementation, urine supplementation must be seen, the concentration cannot exceed 0.15%, and the total daily potassium supplementation is 2 ~ 3mmol / , the speed should be slow. The amount of infusion should be small, and the infusion speed should be slow. Except for the urgent need to expand blood volume, generally it should not exceed 10ml / per hour. The neonatal liver has a slow metabolism of lactic acid. Sodium lactate is not used when correcting acidosis, but sodium bicarbonate is used, but hypertonic sodium bicarbonate is prohibited.

2.5 Application of oral rehydrationsalts (ORS)

0RS is a solution recommended by the World Health Organization for the treatment of acute diarrhea with dehydration. Good results have been obtained through clinical application, and it is especially applicable to developing countries. The theoretical basis is based on the Na + -glucose coupling transport and absorption mechanism of the small intestine. There is a Na + -glucose common carrier on the membrane of the brush border of small intestinal epithelial cells. This carrier has two Sa + -glucose binding sites. When Na + -glucose At the same time, it can work when combined with the binding site, and significantly increase the absorption of sodium and water.

As of 2018, there are various ORS formulations. The various electrolyte concentrations recommended by the WHO for oral rehydration salts are Na + 90 mmol / L, K + 20 mmol / L, C1-80 mmol / L, HC03-30mmol / L, and glucose 111 mmol / L. It can be made up with 3.5g of NaCl, 2.5g of NaHCO2, 1.5g of potassium citrate, 20.0g of glucose, and water to 1000ml. The electrolyte has an osmotic pressure of 220 mmol / L (2/3 sheets) and a total osmotic pressure of 310 mmol / L. The concentration of glucose in this solution is 2%, which is beneficial to the absorption of Na + and water; the concentration of Na + is 90mmol / L, which is suitable for correcting the cumulative loss and electrolyte loss in feces; it contains a certain amount of potassium and bicarbonate, which can Supplement potassium and correct acidosis. ORS is generally suitable for people with mild or moderate dehydration without severe vomiting, and can also be used to supplement the amount of fluid that continues to be lost.

Special reminder: After dehydration occurs in the body, you should not drink a lot of white boiling water for a short period of time, because water cannot reach the cells, causing further edema of the cells, which will cause water poisoning.

What Is Acute Dehydration?

Acute dehydration

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