Perioperative fluid replenishment

Metabolism of water

Body fluids in the human body are discharged from the body through four channels.

1. Renal urination: Generally, the daily urine volume is about 1000-1500l. The daily urine volume is at least 500l. Due to the daily metabolism of the human body, 5-40g of solid waste can be produced. Every 15l of urine can be excreted 1g of solid waste.

2. Evaporation and sweating of the skin: The water evaporated from the skin every day is about 500l. The water evaporated in this way is relatively constant and does not decrease due to lack of water in the body. If sweating occurs, more water will be lost from the skin. If there is fever, every 1c increase in body temperature, the water lost from the skin will increase by 100l.

, The lungs exhale water: Normal people lose about 400l of water from exhalation every day. This loss of water is also constant and is not reduced due to lack of water in the body.

4. Digestive tract drainage: The gastrointestinal secretes 8200l of digestive fluid every day, and most of it is reabsorbed, and only about 100l is excreted from feces; gastric juice is acidic, and the rest is alkaline; potassium in gastric juice is -5 times that of plasma.

The total amount of water discharged from the body through various channels above is about 2000-2500l. The water exhaled by the lungs is generally invisible, which is called non-obstructive loss of water.

The water consumed by normal people is equal to the water discharged. The amount of water discharged by the human body every day is the amount of water required, about 2000-2500l. These water mainly come from 1000-1500l of drinking water and the water contained in solid or semi-solid foods consumed. The water generated by the oxidation process in the body is about 200-400l of water. If an adult who cannot eat does not lose additional water, minus the endogenous water, 2000l is the minimum physiological need.

Electrolyte

1. Sodium ions: The extracellular fluid is mainly cationic, which maintains the osmotic pressure and capacity of the extracellular fluid. The kidney excretion of sodium is more sodium and more, less sodium and less sodium, and no sodium. No sodium is discharged. Normal adults discharge about 45-6g of sodium every day, and the normal amount is also 45-6g.

2. Potassium ions: The intracellular fluid is mainly cations, and potassium has a significant effect on nerve-muscle stress, myocardial tone and excitability. When cells synthesize glycogen and protein, potassium enters the cell from the outside of the cell; when cells decompose glycogen and protein, potassium moves out of the cell from the outside of the cell. The kidneys have always maintained a state of potassium excretion. Although the excretion is reduced when the potassium content in the body is small, it is limited, and the amount of potassium excretion is basically close to that of the daily excretion. Normal adults discharge about -5g of potassium per day, and the normal amount is also this value.

,Chloride ions: the main anion of extracellular fluid.

4. Bicarbonate ion: the main anion of extracellular fluid. The two main anions in extracellular fluid, cl- and -, often have mutual compensatory effects. For example, when the cl-loss is lost due to large amounts of vomiting, the -concentration increases, causing low chlorine alkalosis; conversely, when the cl-in is increased due to large amounts of saline, the -concentration decreases, causing hyperchlorine acidosis.

Combined with the water requirements mentioned above, the liquid that must be replenished every day. Adults who cannot eat need to supplement their saline daily and 20-0l of 10% potassium chloride. Other liquids can be replenished with glucose, which means 5% or 10% glucose 1500l. After glucose metabolism, calories are generated to produce water and carbon dioxide; carbon dioxide is exhaled from the respiratory tract, so the amount of glucose liquid can be calculated as water.

Osmotic pressure

The normal plasma osmotic pressure is 00s/l, and the balance of osmotic pressure plays a decisive role in maintaining the body fluid capacity. The normal osmotic pressure balance is regulated by: 1: The hypothalamus-posterior pituitary-antidiuretic hormone system. When the osmotic pressure increases, the secretion of antidiuretic hormones is increased through the hypothalamus-posterior pituitary-antidiuretic hormone system, and the reabsorption of water by the renal tubules increases, the urine volume decreases, and the osmotic pressure decreases, and vice versa. 2: The renin-aldosterone system restores blood volume. When the blood volume decreases, the secretion of aldosterone is increased through the renin-aldosterone system, and the renal water, sodium recovery increases, urine volume decreases, and blood volume increases, and vice versa.

Acid-base balance

The normal blood ph is 5-45. The main ways to maintain acid-base balance are: 1. The blood buffering system: the most important buffering pair is the ratio of -/20/1; when the body produces a lot of acid, it is from - and; when the alkali is produced a lot of alkali, it is from and. 2. Pulmonary regulation: the blood concentration is adjusted by increasing or decreasing the amount of CO2 discharge. When the concentration increases, breathing deepens and accelerates the excretion of CO2; vice versa. 3. Renal regulation: The kidney has a strong acid discharge ability. The specific path is: a mainly relies on the exchange of h and na, and the reabsorption of S and; secretes hn4 to bring out h; and directly discharges h2so4 and hcl.

2. Body fluid imbalance

Dehydration

1. Hyperosmotic dehydration: caused by insufficient water intake and excessive sweating. Due to the loss of water greater than sodium loss, the extracellular fluid is in a hyperosmotic state, resulting in intracellular dehydration, increased secretion of antidiuretic hormones, and decreased urine output. The clinical manifestations are mainly water deficiency, which can be divided into degrees: 1 Mild: obvious thirst, water loss accounts for 2%-4% of the body weight; 2 degrees: severe thirst, fatigue, less urine, decreased skin elasticity, depression of eye sockets, irritability, and water loss accounts for 4%-6% of the body weight; 3 degrees: Symptoms worsen, high fever, coma, convulsions, and water loss accounts for more than 6% of the body weight. Hyperosmotic dehydration is greater than 150l/l, and the treatment is mainly for hydration.

2. Hyposmotic dehydration: after acute water loss, only

^0^Remember in one second

Replenish hydration and ignore salt replenishment; or repeated vomiting. Because sodium loss is greater than water loss, the extracellular fluid is hypotonic. The secretion of antidiuretic hormones in the early stage is reduced, the urine volume increases, and the blood volume is insufficient; the secretion of aldosterone increases, and the urine volume is reduced. The clinical manifestations are mainly sodium deficiency, which can be divided into degrees: 1 mild: no thirst, fatigue, dizziness, and urine volume does not decrease, and salt loss is about 05g/g; 2 degrees: reduced skin elasticity, nausea, vomiting, weak pulse, low blood pressure, and reduced urine volume, and salt loss is about 05-05g/g; 3 severe: In addition to the above symptoms, shock occurs, and salt loss is about 05-125g/g. Hyposmotic dehydration mildly has less than 15l/l, and blood sodium less than 10l/l, and severe blood sodium less than 120l/l. Treat isotonic saline first, and severe cases should be supplemented with hypertonic saline.

, isotonic dehydration: The most common dehydration in surgery is caused by acute body fluid loss. The ratio of lost water to sodium is the same, mainly due to loss of extracellular fluid. If the fluid is not replenished in time, it can be transformed into hypertonic dehydration; if the fluid is not replenished in time, it can be transformed into hypotonic dehydration. The clinical manifestations are insufficient blood volume, which can be divided into degrees: 1 mild: thirst, less urine, fatigue, and loss of water accounts for about 2%-4% of body weight; 2 degrees: dry lips, positive dehydration signs, fine pulse, low blood pressure, and loss of water accounts for about 4%-6% of body weight; 3 severe: the above symptoms worsen, shock occurs, and loss of water accounts for about 6% of body weight. Isotonic dehydration is in the normal range. Treatment is mainly for supplementing balanced salt solution.

Hypokalemia

Serum potassium is less than 5l/l, which is hypokalemia. Common causes of hypokalemia are: long-term fasting causes insufficient potassium intake; vomiting and diarrhea cause excessive potassium loss; alkalinity leads to internal transfer of extracellular potassium and long-term use of diuretics to cause excessive potassium excretion.

Clinical manifestations of hypokalemia: 1. Symptoms of decreased excitability of the pivot and peripheral nerves: fatigue, drowsiness, weakened or disappeared tendon reflexes; 2. Symptoms of the digestive system: vomiting, abdominal distension, and weakened intestinal rumbling; 3. Symptoms of the circulatory system: arrhythmia, electrocardiogram changes.

Treatment of hypokalemia: First, treat the primary cause, and then replenish potassium in time. When replenishing potassium, be careful not to do intravenously if you can take it orally, and see potassium supplementation. The concentration should not be too high during intravenous administration, the speed should not be too fast, and the dosage should not be too large.

Hyperkalemia

Serum potassium is higher than 55l/l, which is hyperkalemia. Common causes of hyperkalemia are: excessive potassium intake, reduced potassium excretion, and abnormal potassium distribution in the body.

Clinical manifestations of hyperkalemia: 1. Fluid limbs, severe limp paralysis; 2. Pale skin and abnormal sensation; 3. Arrhythmia, slow heartbeat, low blood pressure, etc.

Treatment of hyperkalemia: First, stop all potassium entry; second, potassium reduction should be reduced in time; potassium excretion; and anti-potassium.

Metabolic acidosis

Metabolic acidotoxic surgery is the most common. The common causes of metabolic acidotoxicity are: excessive acid production in the body; excessive alkali loss; and renal acid excretion disorder.

Clinical manifestations of metabolic acidosis: 1. Respiration deepens and accelerates, exhaled gases have a rotten apple smell; 2. Suffering spirit, dizziness, drowsiness; 3. Accelerating heartbeat, low blood pressure; 4. Test tests: ph is less than 5, -decreasing, and urine is acidic.

Treatment of metabolic acidotoxicity: 1. Treat the primary disease and eliminate the causes of acidotoxicity; 2. Mild metabolic acidotoxicity can be relieved by rehydration; 3. Severe metabolic acidotoxicity requires alkaline solution to be corrected. The commonly used clinically is 5% sodium bicarbonate. The dosage calculation formula is: 5% sodium bicarbonate = x weight x0. Generally, 1/2 of the calculated amount is given first to avoid excessive acid replenishment.

Metabolic alkalosis

Common causes of metabolic alkalosis are: pyloric obstruction, high-level intestinal obstruction, long-term gastrointestinal decompression, etc., which lead to excessive acid loss, resulting in excessive in the body. Metabolic alkalosis is often accompanied by hypokalemia, hypocalcemia and hypochlorous chlorine.

Clinical manifestations of metabolic alkalosis: 1. Slowering breathing; 2. Dizziness, drowsiness; 3. Arrhythmia, low blood pressure; 4. Convulsions of feet.

Treatment of metabolic alkalosis: 1. Treat the primary disease and eliminate the causes of alkalosis; 2. Mild metabolic alkalosis can be relieved by self-relieving by isotonic saline; 3. Severe metabolic alkalosis requires alkaline drugs to be corrected. Those who can take orally can take amine chloride orally, and those who take orally should not use dilute hydrochloric acid intravenously. When foot convulsions occur, use 10% calcium gluconate intravenously.

, rehydration

Develop a fluid replenishment plan

1. Develop a fluid replenishment plan based on the patient's clinical manifestations and laboratory test results. The fluid replenishment plan should include contents: 1. Estimate the accumulated amount of water that may be lost before admission to the hospital; 2. Estimate the amount of fluid lost by the patient yesterday, such as vomiting, diarrhea, gastrointestinal decompression, intestinal fistula, etc.; the amount of fluid lost by high heat; the amount of fluid lost by tracheostomy; the amount of fluid lost by excessive sweating, etc.; 3. The amount of fluid required for normal physiology every day, calculated in 2000l.

2. What to supplement? Choose according to the specific situation of the patient: 1. Commonly used crystal liquids: glucose saline, isotonic saline, balanced salt solution, etc.; 2. Commonly used for colloidal liquids: blood, plasma, dextran, etc.; 3. Commonly used for supplementing calories: 10% glucose saline; 4. Commonly used for alkaline liquids: 5% sodium bicarbonate or 112% sodium lactate, to correct acidosis.

, How to replenish? Specific replenishment method: 1. Replenishment procedure: first expand capacity, then adjust the balance of positive electrolyte and acid-base; when expanding capacity, use crystals first and then colloids; 2. Replenishment speed: fast first and then slow. Usually 60 drops per minute, equivalent to 250l per hour. Note: heart, brain,

^0^Remember in one second

People with renal dysfunction should replenish fluids slowly, and the speed should be slow when replenishing potassium; the speed should be fast when rescuing shock, and the speed should be fast when dehydrating with mannitol.

Principles of rehydration

1. The order of replenishing fluids: first salt and then sugar, see urine to replenish potassium. The main loss of body fluids is gastrointestinal fluid, plasma or blood, which are isotonic. In order to restore blood volume, isotonic liquid should be used to replenish it. Although glucose liquid is also isotonic or even hypertonic, it is metabolized quickly after infusion and becomes water and carbon dioxide, which cannot achieve the purpose of restoring blood volume. The total amount of potassium in dehydrated patients is insufficient, but in the case of lack of water, the blood is concentrated and the patient's blood potassium may not be low. Additional potassium supplementation may increase blood potassium and lead to hyperkalemia. Only when the urine volume reaches more than 40 ml per hour, potassium supplementation is safe.

Anti-collection, automatic loading fails, click to load, reading mode does not support!

Transcoding is prohibited, reading mode is prohibited, the following content is hidden, please exit reading mode!

4. Living within your means: The patient's water loss before visiting is estimated based on the patient's dehydration performance and is not very accurate. The water loss after visiting the doctor should be accurately measured and recorded. The subsequent water loss should be based on the recorded water loss and how much it is supplemented.

Monitoring indicators for safe fluid replenishment

1. Cardiac venous pressure: Normally, 5-10 water column. CVP and blood pressure are reduced at the same time, indicating insufficient blood volume, and replenishment should be accelerated; CVP increases and lower blood pressure means cardiac insufficiency, and replenishment should be slowed down and cardiac strengthening drugs should be given; CVP is normal, and blood pressure is reduced, indicating insufficient blood volume or cardiac insufficiency, and replenishment tests should be performed.
Chapter completed!