Metabolic alkalosis

Introduction to metabolic alkalosis Metabolic alkalosis refers to the clinical situation in which the body loses too much acid or enters too much alkali from the body. The main biochemical manifestations are blood HCO3-high and PaCO2 increase. The pH value varies depending on the compensation situation and can be significantly too high; it can also be mildly elevated or even normal. The disease is often accompanied by hypokalemia. The primary cause of metabolic alkalosis is that the extracellular fluid loses a large amount of acid or absorbs a large amount of alkali, resulting in an increase in HCO3-, thus [BHCO3]/[HHCO3] The larger the molecule causes the pH to rise. Symptoms of alkaloids include numbness, tingling, wrist and ankle and arrhythmia. But often covered by the primary disease. With low calcium, hand and foot convulsions may occur; with low potassium, polyuria, polydipsia and paralysis may occur; with low volume, postural vertigo and muscle weakness may occur. In severe cases, there may be confusion, unresponsiveness, and even paralysis. basic knowledge The proportion of illness: 0.12% Susceptible people: no specific people Mode of infection: non-infectious Complications: respiratory alkalosis

Causes of metabolic alkalosis

Primary factor (25%):

The primary factor of metabolic alkalosis is that the extracellular fluid loses a large amount of H or absorbs a large amount of alkali, so that HCO ₃ - increases, which causes the molecular weight of [BHCO ₃ ] / [HHCO ₃ ] to increase and cause an increase in pH. .

1, gastric juice loss, vomiting, long-term gastric aspiration, pyloric obstruction, after surgery anesthesia, can lose a lot of gastric juice.

2, lack of potassium.

Extracellular fluid Cl- reduction (20%):

Extracellular fluid Cl- reduced, such as decreased intake, or loss of gastric juice, or due to the use of furosemide, thiazide diuretics, loss of large amounts of Cl- through the kidney, or functional defects in the absorption of Cl- by congenital intestinal mucosal cells Etc., can reduce the extracellular fluid Cl-.

Bicarbonate accumulation (15%):

(1) When treating gastric ulcer disease, long-term use of a large amount of alkaline drugs reduces or eliminates gastric acid, so that the bicarbonate in the intestinal juice is absorbed into the blood without being neutralized, and the amount of HCO ₃ - in the blood is greatly increased. Alkalosis occurs.

(2) Excessive intake of organic acid salts, oral or injection of lactate, citrate (large amount of blood transfusion), when the acetate is too much, they are converted into CO ₂ and H ₂ O in the liver, and hydrogen carbonate is formed. Salt causes a large increase in the content of HCO ₃ - in the blood, which contributes to alkalosis.

(3) A large amount of sodium bicarbonate is used during cardiopulmonary resuscitation. After resuscitation, the lactate is metabolized and the consumed HCO ₃ - can be recovered. As a result, the HCO ₃ in the blood is as high as 60 to 70 mmol/L, pH. The value is 7.90. In addition, in the case of renal failure, metabolic alkalosis can also occur if too much sodium bicarbonate is used.

Metabolic alkalosis prevention

Early detection and early treatment are the key to prevention. The disease is usually secondary to other respiratory diseases, digestive systems, and blood system diseases. Therefore, patients with these diseases should be treated aggressively, and while monitoring the primary disease, pay attention to monitoring the fluctuations of the internal environment. In particular, the use of some basic drugs such as sodium bicarbonate must be adequately indicated to avoid iatrogenic metabolic alkalosis caused by overuse.

Metabolic alkalosis complications Complications, respiratory alkalosis

1. Acid-base poisoning : Acidosis refers to the primary reduction of any alkaline substance or the primary increase of acidic substances, and the pH value may be abnormal (uncompensated or insufficient compensation) or normal (fully compensated or complex type) Conversely, alkalosis refers to the primary increase of any alkaline substance or the primary decrease of acidic substances, and the pH value may be abnormal (uncompensated or insufficient compensation) or normal (fully compensated or complex type) Disorder), complex acid-base disorders can lead to more significant changes in pH (such as respiratory acidosis combined with metabolic acidosis), can also restore the pH to normal (such as respiratory acidosis combined with metabolic alkalosis), at pH Patients with normal acidosis or alkalosis do not need to supplement basic or acidic drugs, only need to deal with the primary disease or induced factors.

2, acid-alkaliemia : acidemia refers to the pH value is less than the normal value, alkalinosis refers to the pH value is greater than the normal value, in patients with severe acidosis need to add alkaline drugs, and patients with severe alkalemia need to be supplemented Acidic drugs, acidemia can be simple acidosis, acidosis and alkalosis (such as severe respiratory acidosis combined with mild metabolic alkalosis), and alkaliemia can be simple alkalosis or alkali Poisoning combined with acidosis (such as severe respiratory alkalosis with mild metabolic acidosis).

Therefore, acid-base poisoning and acid-alkaliemia are both different and related. Acid-alkaliosis must be combined with acid-base poisoning, while acid-base poisoning does not necessarily involve acid-baseemia. It is clinically treated with alkaline or acidic drugs. It is acidosis, not general acid-base poisoning.

3, alkali poisoning: the heart and brain vasoconstriction, blood supply reduction, further aggravation of tissue hypoxia.

4. Hypokalemia .

Symptoms of metabolic alkalosis Common symptoms Lack of urinary tract reflexes, manic sleepiness, restlessness, coma, dance, hand, foot, movement, no urine, low metabolism, low toxicity

1. Breathing is shallow and slow. It is the compensation phenomenon of metabolic alkalosis caused by respiratory system. By means of shallow and slow breathing, PCO _{2 in} alveoli can be increased, and the denominator of [BHCO ₃ ]/[HHCO ₃ ] can be added. Large to reduce the ratio change (stabilized pH) that occurs as the molecule becomes larger.

2, mental symptoms: incitement, excitement, slang, lethargy, serious coma.

3, increased neuromuscular excitability, there are hand and foot sputum, sputum reflexes and so on.

4, less urine, alkaline; if potassium deficiency has occurred, there may be contradictions of acidic urine, special attention should be paid to standard hydrogen carbonate (SB), actual hydrogen carbonate (AB), buffer base (BB), alkali residue ( BE) increased, blood PCO ₂ , blood pH increased.

Examination of metabolic alkalosis

1, blood gas analysis and detection, oxygen partial pressure, oxygen saturation detection, according to blood gas analysis HCO ₃ -, PH, BE and other test results, that is, can be initially determined whether there is metabolic alkalosis.

2, blood electrolyte sodium, potassium, calcium, magnesium, phosphorus detection.

3, liver and kidney function tests, early detection of acid-induced liver and kidney damage, renal metabolic function is affected when alkalosis, if there is a combination of hypokalemia, abnormal acidic urine can occur, so according to the urine PH There is a possibility of hypokalemia.

4, clinically, metabolic sputum poisoning is often caused by pyloric obstruction can be diagnosed by X-ray barium or gastroscopy.

Diagnosis and identification of metabolic alkalosis

According to the medical history, physical signs and blood gas analysis of AB, SB, BB, BE, blood PCO2, blood pH values are increased, the diagnosis of metabolic alkalosis can be obtained, and the formula for compensating metabolic acidosis is:

PCO ₂ = 0.9 × [HCO ₃ -] ± 5.

PCO _{2 =} 40 0.9 × [HCO ₃ -] ± 5.

1. If the measured PCO ₂ 40 0.9 × [HCO ₃ -] ± 5, it means that the metabolic alkalosis has reached the maximum compensation.

2. If the measured PCO ₂ <40 0.9×[HCO ₃ -]±5, it may be metabolic alkalosis with respiratory alkalosis, or mild metabolic alkalosis, or less than 12 due to onset time. ~24h, has not reached the maximum compensation, or because of the stimulation of breathing factors.

3. If the measured PCO ₂ >40 0.9×[HCO ₃ -]±5, it may be metabolic alkalosis with respiratory acidosis, or metabolic alkalosis with metabolic acidosis, or excessively compensated metabolism. Alkalosis.

The disease should be distinguished from metabolic acidosis, respiratory acidosis, and respiratory alkalosis.

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