What are the normal ranges for pH in ABG interpretation?
7.35 - 7.45
Absolute normal = 7.40
What is the normal range for PaCO2 in ABG interpretation?
35 - 45 mm Hg
This value reflects the partial pressure of carbon dioxide in arterial blood.
What is the normal range for HCO3- in ABG interpretation?
22 - 26 mEq/L
This value indicates the concentration of bicarbonate in the blood.
What is the normal range for PaO2 in ABG interpretation?
80–100 mm Hg
This value measures the partial pressure of oxygen in arterial blood.
What is the normal oxygen saturation level?
>94%
This indicates the percentage of hemoglobin saturated with oxygen.
What is the major extracellular fluid buffer system?
Bicarbonate–carbonic acid buffer system
Which organ regulates bicarbonate in extracellular fluid?
Kidneys
Kidneys can regenerate bicarbonate ions as well as reabsorb them from the renal tubules
Kidneys also retain Hydrogen ions and excrete bicarbonate when in alkalosis.
This process is slow… takes hours or days
Which organ regulates the carbonic acid level of the ECF?
Lungs
Under contol of the medulla, the lungs raise or lower the respiratory rate in response to amount of CO2 in the arterial blood.
What are the clinical manifestations of metabolic acidosis?
- Headache
- Confusion
- Drowsiness
- Increased respiratory rate and depth
- Decreased blood pressure
- Decreased cardiac output
- Dysrhythmias
- Shock
Low pH, Low HCO3
Symptoms may vary based on the severity and speed of onset.
What are some causes of metabolic acidosis?
- Salicylate poisoning
- Renal failure
- Propylene glycol toxicity
- Diabetic ketoacidosis
- Starvation/Malnutrition
Low pH, Low HCO3
What is the treatment for metabolic acidosis?
- Correct underlying problem
- Administer bicarbonate
- Monitor serum electrolytes
- Monitor potassium levels
- Hemodialysis
- Peritoneal dialysis
What are the clinical manifestations of metabolic alkalosis?
- Symptoms related to decreased calcium
- Respiratory depression
- Tachycardia
- Symptoms of hypokalemia (tingling, dizziness, tetany)
- ECG changes
- Decreased GI motility
High pH, High HCO3
What are some causes of metabolic alkalosis?
- Vomiting
- Gastric suction
- Medications (diuretics)
- Hyperaldosteronism
- Cushing’s syndrome
- Hypokalemia
High pH, High HCO3
What is the treatment for metabolic alkalosis?
- Correct the underlying acid-base disorder
- Restore fluid volume with sodium chloride solutions
- Monitor I&O
- Monitor for ECG and neurologic changes
What are the clinical manifestations of respiratory acidosis?
- Sudden increased pulse
- Increased respiratory rate
- Increased BP
- Mental changes
- Feeling of fullness in head
- Increased conjunctival vessels
Low pH, High PaCO2
Symptoms can vary based on whether the condition is acute or chronic.
What are some causes of respiratory acidosis?
- Pulmonary edema
- Overdose
- Atelectasis
- Pneumothorax
- Severe obesity
- Pneumonia
- COPD
- Muscular dystrophy
- Multiple sclerosis
- Myasthenia gravis
Low pH, High PaCO2
These conditions lead to inadequate ventilation and CO2 retention.
What is the treatment for respiratory acidosis?
- Improve ventilation
- Bronchodilators
- Antibiotics
- Anticoagulants
- Pulmonary physiotherapy
- Adequate hydration
- Mechanical ventilation if necessary
Treatment focuses on enhancing respiratory function.
What are the clinical manifestations of respiratory alkalosis?
- Lightheadedness
- Inability to concentrate
- Numbness and tingling in extremities
- Tachycardia
- Ventricular and atrial arrhythmias
High pH, Low PaCO2
Symptoms arise from hyperventilation and decreased CO2 levels.
What are the causes of respiratory alkalosis?
Always due to hyperventilation
- Extreme anxiety
- Panic disorder
- Hypoxemia
- Salicylate intoxication
- Gram-negative sepsis
- Inappropriate ventilator settings
High pH, Low PaCO2
These factors lead to hyperventilation and decreased CO2.
What is the treatment for respiratory alkalosis?
- Treat the underlying cause
- Antianxiety agent
- Have patient breathe into a bag
- Monitor anxiety and respiratory status
Treatment aims to address the cause and stabilize the patient.
What is the interpretation of the following ABG: pH = 7.5, PaCO2 = 37, HCO3 = 30?
Metabolic Alkalosis
The pH is above normal, indicating alkalosis, with HCO3 also elevated.
What is the compensatory mechanism for Respiratory Alkalosis?
Kidneys make LESS bicarb = less base = pH goes ⬇️
What is the compensatory mechanism for Metabolic Alkalosis?
Lungs retain MORE CO2 = more acid = pH goes ⬇️
What is the compensatory mechanism for Metabolic Acidosis?
Lungs retain LESS CO2 = less acid = pH goes ⬆️
