Overview.
Mixed acid-base imbalance is a clinical condition in which two or more metabolic or respiratory acid-base imbalances occur simultaneously.
Etiology
Most often caused by a variety of critical illnesses leading to severe vomiting, drug intoxication and severe electrolyte disorders.
Symptoms
Because of the complexity of the pathophysiologic changes in mixed acid-base balance disorder, the clinical manifestations are not typical.
1. Mixed acidosis, i.e. respiratory acidosis combined with metabolic acidosis
It is a kind of mixed acid-base balance disorder which is more common in clinic. Most often seen in cardiac arrest, bronchial asthma, severe pulmonary edema patients, manifested as shortness of breath, dyspnea, headache, flushing, rapid heart rate, arrhythmia, irritability.
2. Mixed alkalosis, i.e. metabolic alkalosis combined with respiratory alkalosis.
Mostly seen in severe vomiting and fever. Mild patients do not have typical signs and symptoms, acute or severe patients, can be manifested as restlessness, impaired consciousness, tetany, convulsions, muscle paralysis, severe pain, children have a history of crying.
3. Respiratory acidosis combined with metabolic alkalosis
It is a kind of mixed acid-base balance disorder which is more common in clinic. It is commonly seen in patients with severe lung disease or chronic pulmonary heart disease combined with vomiting, manifested by shortness of breath, dyspnea, headache, agitation, impaired consciousness, convulsions, and muscle paralysis.
4. Metabolic acidosis combined with respiratory alkalosis
Mostly seen in severe vomiting combined with diarrhea and patients. The manifestations are flushing, rapid heart rate, arrhythmia, decreased blood pressure, and even coma.
5. Metabolic acidosis combined with metabolic alkalosis
Mostly seen in patients with renal insufficiency or diabetic acidosis. The manifestations are flushing, accelerated heart rate, decreased blood pressure, tachycardia, convulsions, muscle paralysis, impaired consciousness and even coma.
6. Respiratory acidosis combined with metabolic acidosis and metabolic alkalosis
The manifestations are shortness of breath, dyspnea, headache, restlessness, tetany, convulsions, muscle paralysis.
7. Respiratory alkalosis combined with metabolic acidosis and metabolic alkalosis
The manifestations are flushing, accelerated heart rate, arrhythmia, tachycardia, convulsions, even coma, etc. Some manifestations are severe pain, and the children have a history of crying, etc.
Examination
Blood gas analysis is the main examination used to diagnose acid-base balance disorder.
1. Respiratory acidosis combined with metabolic acidosis
It is characterized by a significant decrease in pH, a decrease in actual bicarbonate (AB), standard bicarbonate (SB), buffer base (BB), AB>SB, an increase in partial pressure of alveolar oxygen (PaCO2), an increase in anion gap (AG), and an increase in plasma K+ concentration.
2. Metabolic alkalosis combined with respiratory alkalosis
Characterized by: a significant increase in pH, SB, AB, BB are increased, AB2 decreased, plasma K + concentration decreased.
3. Respiratory acidosis combined with metabolic alkalosis
Characterized by: normal or elevated pH, can also be reduced, SB, AB, BB, PaCO2 are elevated, AB>SB, residual base (BE) positive value increased.
4. Metabolic acidosis combined with respiratory alkalosis
Characterized by normal or slightly high or low pH, decreased SB, AB, BB, PaCO2, AB<SB, and increased negative value of residual base (BE).
5. Metabolic acidosis combined with metabolic alkalosis
Characterized by: pH, HCO3- and PaCO2 can be within the normal range, AG increased.
6. Respiratory acidosis combined with metabolic acidosis and metabolic alkalosis
Characterized by: PaCO2 increased significantly, HCO3-concentration generally increased, AG>16mmol/L, CL-concentration decreased significantly.
7. Respiratory alkalosis combined with metabolic acidosis and metabolic alkalosis
It is characterized by a significant decrease in PaCO2, HCO3-concentration may be high or low, AG>16mmol/L, and a decrease in CL-concentration.
Diagnosis
Combine with history, clinical manifestations and blood gas analysis results for comprehensive analysis and judgment.
Treatment
Firstly, deal with the primary disease and predisposing factors, then treat according to each simple type of acid-base imbalance, and continuously adjust the treatment program according to the results of blood gas analysis in the course of treatment.