Question

Concepts of respiratory and metabolic acidosis and respiratory and metabolic alkalosis. Include lab and blood gas values, causes and treatment, as well as signs and symptoms in each of the four conditions. Highlight similarities and differences.

Answer 1

Blood gases is a measurement of how much oxygen and carbon dioxide is in your blood. It also determines the acidity (pH) of your blood.

Normal values:
Partial pressure of oxygen (PaO2) - 75 - 100 mmHg
Partial pressure of carbon dioxide (PaCO2) - 38 - 42 mmHg
Arterial blood pH of 7.38 - 7.42
Oxygen saturation (SaO2) - 94 - 100%
Bicarbonate - (HCO3) - 22 - 28 mEq/L

Respiratory acidosis is a condition that occurs when the lungs can’t remove enough of the carbon dioxide (CO2) produced by the body. Excess CO2 causes the pH of blood and other bodily fluids to decrease, making them too acidic. Acidosis occurs when the pH of the blood falls below 7.35.

This may be due to a decrease in respiratory rate or decrease in air movement due to an underlying condition such as:

• asthma
• pneumonia
• sleep apnea
• chronic obstructive pulmonary disease (COPD)
• acute pulmonary edema
• severe obesity
• neuromuscular disorders (such as multiple sclerosis or muscular dystrophy)
• scoliosis

Initial signs of acute respiratory acidosis include:

• headache
• anxiety
• blurred vision
• restlessness
• confusion

Without treatment, other symptoms may occur. These include:

• sleepiness or fatigue
• lethargy
• delirium or confusion
• shortness of breath
• coma

The chronic form of respiratory acidosis doesn’t typically cause any noticeable symptoms. Signs are subtle and nonspecific and may include:

• memory loss
• sleep disturbances
• personality changes

Treatment:

• antibiotics (to treat infection)
• diuretics (to reduce excess fluid affecting the heart and lungs)
• bronchodilators (to expand the airways)
• corticosteroids (to reduce inflammation)
• mechanical ventilation (in severe cases)

Metabolic acidosis is a condition in which there is too much acid in the body fluids.

Causes:

• Alcohol
• Cancer
• Exercising intensely
• Liver failure
• Medicines, such as salicylates
• Prolonged lack of oxygen from shock, heart failure, or severe anemia
• Seizures
• Kidney disease (distal renal tubular acidosis and proximal renal tubular acidosis)
• Poisoning by aspirin, ethylene glycol (found in antifreeze), or methanol
• Severe dehydration

Symptoms:

rapid breathing. Acting confused or very tired

Treatment:

• Sodium bicarbonate
• IV fluids

Respiratory alkalosis occurs when the levels of carbon dioxide and oxygen in the blood are not balanced.Respiratory alkalosis occurs when you breathe too fast or too deep and carbon dioxide levels drop too low. This causes the pH of the blood to rise and become too alkaline. When the blood becomes too acidic, respiratory acidosis occurs.

Causes:

• Panic attacks
• anxiety
• heart attack
• pain
• drug use
• asthma
• fever
• chronic obstructive pulmonary disease
• infection
• pulmonary embolism
• pregnancy

Symptoms:

• dizziness
• bloating
• feeling lightheaded
• numbness or muscle spasms in the hands and feet
• discomfort in the chest area
• confusion
• dry mouth
• tingling in the arms
• heart palpitations
• feeling short of breath

Treatment:

• Breath into bag
• Get reassurance
• Restrict oxygen intake

Metabolic alkalosis is primary increase in bicarbonate (HCO3−) with or without compensatory increase in carbon dioxide partial pressure (Pco2); pH may be high or nearly normal.

Causes:

prolonged vomiting, hypovolemia, diuretic use, and hypokalemia and renal impairment.

Symptoms:

headache, lethargy, and tetany.

Treatment:

The underlying condition is treated; oral or IV acetazolamide or hydrochloric acid is sometimes indicated.