Acid Base Balance Flashcards
Why is maintenance of pH important?
Protein structure
Metabolism and Enzymes
What determines pH?
pCO2
Addition or removal of acids (H+)
Strong ion movements
Serum proteins, phosphates, and other weak acids
What are the regulatory systems of blood pH?
Extracellular and intracellular buffers
Rate of alveolar ventilation
Renal excretion of H+
What is the reason for buffer systems?
Minimize the changes in H+
Prevent sudden changes in pH
What are the components of the buffer system?
Bicarbonate/carbonic acid
Non bicarbonate components: Hemoglobin, Plasma Proteins, others
What are venous samples used for?
Good for evaluating acid base status
What are arterial samples used for?
Evaluate pO2
Useful for evaluating cardiopulmonary function
What tube is Blood gas analysis collected in?
Green Top Tube with Heparin
TCO2
Bicarbonate
pCO2
Acid
pCO2
Respiratory
HCO3
Metabolic
Increase of pH
Alkalemia
Decrease of pH
Acidemia
What causes Respiratory Acidosis
Hypoventilation
What causes Respiratory Alkalosis?
Hyperventilation
What causes Metabolic Acidosis?
Increased acid in the absence of increased pCO2
Decreased HCO3
What causes Metabolic Alkalosis?
Decreased acid in the absence of decreased pCO2
Increased HCO3
Measurement of TCO2
Estimate of plasma bicarbonate concentration
Base Excess
Characterizes the overall metabolic acid-base status independent of the respiratory acid-base status
Metabolic alkalosis
+ Base Excess
Metabolic Acidosis
- Base Excess
What are the 4 primary acid base abnormalities?
Respiratory Acidosis
Metabolic Acidosis
Respiratory Alkalosis
Metabolic Alkalosis
What is the body’s compensatory response to abnormal pH?
Opposite system, Opposite type
What causes Hypoventilation
Anesthesia
Diffuse pulmonary disease
Intrathoracic lesions
CNS disease
What is the compensation for Respiratory Acidosis?
Secondary Metabolic Alkalosis = Retention of HCO3
What are the 2 way Metabolic Acidosis can happen?
Increase in acid
Decrease in base
What causes High Anion Gap Acidosis?
Ketones
Lactate
Uremic Acids
Ethylene glycol
What is the calculation for anion gap?
(Na + K) - (Cl+ HCO3)
How is HCO3 lost?
Diarrhea Intestinal ileus Salivation Urinary loss Titration
What is the short term compensation for Metabolic Acidosis?
Increased ventilation with decreased pCO2
What is the long term compensation for Metabolic Acidosis?
Increased renal excretion of H+ with retention of HCO3
What causes Hyperventilation?
Hypoxemia
Pain, Anxiety
Hyperthermia
Drugs that stimulate the medullary respiratory center
What is the compensation for Respiratory Alkalosis?
Secondary Metabolic acidosis = renal retention of H+
What is the 2 way Metabolic Alkalosis can happen?
Decreased Acid
Increased Base
What are the causes of Hypochloremic Metabolic Alkalosis?
Severe vomiting, pyloric obstruction
Sequestration of fluid in abomasum and forestomaches
What causes Excessive Renal loss of H+?
Diuretics
Increased mineralcorticoid activity (aldosterone)
What is the short term compensation for metabolic alkalosis?
Decreased ventilation and increased pCO2
What is the long term compensation for metabolic alkalosis?
Increased renal retention of H+ with decreased generation of HCO3
