Complex acid-base imbalance

Introduction to complex acid-base imbalance Mixed acid-base imbalance (Mixed Acid-BaseDisturbances) refers to the simultaneous existence of two or more simple acid-base balance disorders. In the case of mixed acid-base disorders, the original compensatory response no longer exists, and the pathophysiological changes are more complicated. Clinical manifestations may be atypical. Therefore, a preliminary diagnosis should be made by carefully analyzing the medical history and analyzing the results of blood gas analysis. There are many combinations of mixed acid-base disorders, but it is clearly impossible to have a combination of respiratory acidosis and respiratory alkalosis. When the two primary disorders shift the pH in the same direction, the pH is more pronounced than normal. For example, patients with metabolic acidosis and respiratory acidosis have lower pH than a single disorder. When the two barriers shift the pH in the opposite direction, the pH of the plasma depends on a dominant obstacle, the magnitude of which varies by another offset rather than a single disorder. If the two barriers cause the opposite changes in pH to cancel each other out, the patient's plasma pH can be normal, such as metabolic acidosis combined with respiratory alkalosis. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: hyperkalemia

Compound acid-base imbalance etiology

Etiology: Two or more simple acid-base balance disorders.

Metabolic acidosis

1. Too much acidic substance: too much hydrogen ion is generated, or hydrogen ion is discharged too little.

2. Reduction of bicarbonate ions: too little bicarbonate ion is generated, and bicarbonate ions are excessively discharged.

Metabolic alkalosis

Reduction of acidic substances: excessive discharge of hydrogen ions and excessive loss of gastric juice.

Increased bicarbonate: excessive intake of alkaline substances, increased reabsorption of bicarbonate.

Compound acid-base imbalance prevention

The key to preventing this disease is to treat the primary disease in a timely and correct manner. For diseases that are prone to acid-base balance disorders, such as: large area burns, vomiting and diarrhea caused by severe digestive tract disease, long-term gastrointestinal decompression, diabetic ketoacidosis, long-term use of ventilator for assisted ventilation Patients and patients who are unable to eat normally. According to the characteristics of the patient's disease, the acid-alkaline drug should be used reasonably. It must have corresponding indications before use to avoid excessive acid-base solution or insufficient supplementation, resulting in a complex acid-base balance disorder.

Complex acid-base imbalance Complications hyperkalemia

The complications of this disease vary depending on the type of acid-base balance, and hyperkalemia, respiratory distress syndrome, etc. are common.

Compound acid-base imbalance symptoms Common symptoms Hyperthermia Respiratory alkalosis Hypercapnia Respiratory acidosis Renal failure Shock Ascites diuretic abdominal depression

Mixed acid-base balance disorders are commonly found in the following five categories:

(1) Respiratory acidosis combined with metabolic acidosis

Respiratory acidosis combined with metabolic acidosis can be found in: 1 chronic respiratory acidosis such as obstructive pulmonary disease with toxic shock accompanied by lactic acidosis; 2 acute respiratory acidosis due to cardiac arrest and lactic acid due to hypoxia Acidosis.

(two) respiratory acidosis combined with metabolic alkalosis

Respiratory acidosis combined with metabolic alkalosis is seen in patients with chronic obstructive pulmonary disease who develop hypercapnia, and because of pulmonary heart disease, heart failure, diuretics such as furosemide, diuretic acid and other metabolic alkalosis, this It is also a situation that is often encountered in breathing, heart and kidney departments.

(3) Respiratory alkalosis combined with metabolic acidosis

This mixed acid-base balance barrier can be found in:

1 patients with renal insufficiency have metabolic acidosis, and due to fever and hyperventilation caused by respiratory alkalosis, such as acute renal failure caused by Gram-negative bacilli sepsis with high fever.

2 patients with liver dysfunction can be hyperventilated due to the stimulation of NH3, and lactic acidosis due to metabolic disorders.

3 excessive dose of salicylic acid causes metabolic acidosis, while stimulating the respiratory center and causing hyperventilation.

(4) Respiratory alkalosis combined with metabolic alkalosis

This mixed acid-base balance barrier can be found in:

1 fever and vomiting patients, metabolic alkalosis caused by respiratory alkalosis and vomiting caused by hyperventilation.

2 patients with cirrhosis have ascites.

(5) Metabolic acidosis combined with metabolic alkalosis

Respiratory acid-base poisoning can not exist at the same time, but metabolic acid-base poisoning can coexist. For example, patients with acute renal failure have vomiting or gastric aspiration, but they can have both metabolic acidosis and metabolic alkalosis. presence.

Compound acid-base imbalance check

Mainly do blood gas analysis.

(1) Respiratory acidosis combined with metabolic acidosis: plasma pH decreased significantly, plasma [HCO3-] decreased, Pco2 increased, for example, patient plasma pH was 7.0, Pco2 was 11.3 kPa (85 mmHg), [HCO3-] It is 14.4 mmol (mEq) / L, and BE is -12 mmol (mEq) / L.

(2) Respiratory acidosis combined with metabolic alkalosis: plasma pH can be normal or slightly elevated or decreased, but [HCO3-] and Pco2 are significantly increased, and [HCO3-] elevation is a characteristic of metabolic alkalosis. Elevated Pco2 is a characteristic of respiratory acidosis, and the ratio of the two can remain unchanged or change little. For example, the patient's plasma pH is 7.4, Pco2 is 60 mmHg, plasma [HCO3-] is 34 mEq/L, and BE+14 mEq/L. .

(3) Respiratory alkalosis combined with metabolic acidosis: plasma pH can be normal, mildly rising or decreasing, but plasma [HCO3-] and Pco2 are significantly decreased, [HCO3-] decline is characteristic of metabolic acidosis, Pco2 is a characteristic of respiratory alkalosis. The ratio of the two can remain unchanged or change little. For example, the patient's plasma pH is 7.36, Pco2 is 20mmHg, plasma [HCO3-] is 14mEq/L, and BE is -12mEq/L.

(4) Respiratory alkalosis combined with metabolic alkalosis: plasma pH is significantly increased, plasma [HCO3-] can be increased, Pco2 can be lowered

(5) Metabolic acidosis combined with metabolic alkalosis: plasma pH, [HCO3-], Pco2 can be in the normal range or slightly higher or lower.

Diagnosis and identification of complex acid-base imbalance

The mixed acid-base balance disorder is more complicated, and it must be judged on the basis of sufficient research and analysis of the disease occurrence and development process. However, there are a few mixed acid-base balance disorders that are still difficult to determine. There are still 2.2% who can't make a positive judgment. It can be seen that further research is needed on the principle and technology of judging the acid-base balance disorder.

The identification of this disease is mainly to know which kinds of acid-base balance coexist.

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