Lactic Acid and Lactate Metabolism

What is lactate the product of?

Carbohydrate metabolism.

When is lactic acid produced?

During anaerobic metabolism when cells lack adequate oxygen.

What is the single most important cause of lactic acidosis?

Deficient cell oxygenation in shock.

Increased lactic acid is a marker for what condition?

Hypoxia.

How quickly does lactic acid increase during hypoxia?

Within minutes.

What are the two main causes of lactic acid accumulation?

Excessive production and reduced removal by the liver.

What is the normal value of lactate in venous blood?

0.5-2.2 mEq/L.

What is the normal value of lactate in arterial blood?

0.5-1.6 mEq/L.

What arterial lactate value is considered abnormal?

Values greater than 2.0 mEq/L.

Where is most lactate produced in the body?

Skeletal muscle, brain, and circulating erythrocytes.

How does the liver process normal lactate?

Converts it to glucose.

What conditions can increase lactic acid?

Liver disease, cardiac failure, respiratory failure, hemorrhage, and hypoxia.

What types of severe shock can cause lactic acidosis?

Cardiovascular, hypovolemic, and septic shock.

Why does the system fail to deliver enough oxygen to tissues in severe shock?

Because of reduced cardiac output.

Which organ must remove non-volatile lactic acid?

The liver.

What is a treatment approach for lactic acidosis in shock?

Treat the shock situation and give high FiO2 to quickly convert lactic acid to glucose.

What is a reason to suspect lactic acidosis in a patient?

An unexplained decrease in blood pH with a hypoxia-producing condition.

What defines metabolic alkalosis?

HCO3 accumulation or excessive H+ loss.

What is the compensation mechanism for metabolic alkalosis?

Hypoventilation (Can only raise PaCO2 to 55 mmHg).

What are common causes of metabolic alkalosis?

-Hypokalemia or hypochloremia.

-Nasogastric suction.

-Persistent vomiting.

-Diuretic therapy.

-Steroid therapy.

-Excessive administration of HCO3

Is complete compensation always possible during a severe acid-base imbalance?

No, complete compensation is not always possible.

Can the respiratory system completely adjust a metabolic imbalance?

No, it can adjust it but not completely.

Does kidney compensation for a respiratory imbalance adjust completely?

No, kidney compensation does not adjust completely.

How does the severity of a disturbance affect compensation?

The greater the disturbance, the less likely the compensation occurs completely.

What is a mixed acid-base disorder?

It comprises 2 or more primary disorders.

What are examples of mixed acid-base disorders?

Respiratory and Metabolic Alkalosis, and Respiratory and Metabolic Acidosis.

What are the causes of hypoxia and hypercarbia during CPR?

Lack of perfusion causes hypoxia, and hypoventilation causes hypercarbia.

What acid-base conditions are associated with COPD and hypoxia?

Chronic elevation of CO2 and reduced PaO2.(Adequate tissue oxygenation because of hematocrit and increased cardiac output)

What do severe hypotension and anemia cause?

Reduced perfusion and anemia cause tissue hypoxia and lactic acidosis.

How does poisoning or drug overdose cause respiratory acidosis?

It results in depression of the respiratory center and hypoventilation.

Which drug classes cause depression of the respiratory center?

CNS depressants and anticonvulsants.

What drugs and how do they produce metabolic acidosis?

propylene glycol, formaldehyde They break down and form acids.