13 – Electrolytes Acid-Base Flashcards
1
Q
How can you assess the acid-base disturbances? Which will you need to differentiate between them?
A
- Use chem panel
o Na
o Cl
o HCO3
o Anion gap - Differentiated using blood gas
o pH
o pCO2
o HCO3
2
Q
Metabolic acidosis
A
- Process that is increasing acid (H+) in the blood
o Increased production or ingestion of acid
o Body can’t get rid of acid
o Excess bicarbonate (HCO3- loss) - *result=decreased HCO3-
o Compensation happens immediately (hyperventilation which results in decrease pCO2 on blood gas)
3
Q
Anion gap normally
A
- will have a slight one due to more unmeasured anions compared to cations
4
Q
High anion gap metabolic acidosis
A
- Increase organic acid production or decreased clearance
- Organic acid ingestion
- “titration type” as excess H+ from the extra acid will titrate (decrease) bicarbonate
- *net result
o Increased anion gap
o Decreased bicarbonate - Ex. uremic acids, lactic acids, ketoacids, toxins (anti-freeze)
5
Q
Normal anion gap metabolic acidosis
A
- Excess bicarbonate is loss through GI tract or kidneys
o Severe diarrhea, choke in cattle
o Renal tubular acidosis - “secretory type” or “bicarbonate loss” metabolic acidosis
- Chloride may be retained to maintain electroneutrality=see a relative hyperchloremia
- Net results
o Normal anion gap
o Decreased bicarbonate
o Hyperchloremia (relative to sodium)
6
Q
Metabolic alkalosis
A
- Process that decreases acid in blood
o Loss of H+
o Gain of HCO3 (iatrogenic: loop diuretics, oral antacids, etc) - *result=increased HCO3 in blood
o Compensation happens immediately (hypoventilation which results in increased pCO2 on blood gas)
7
Q
Metabolic alkalosis: loss of H+ through GI tract
A
- Vomiting
- Upper GI obstruction
- *net result
o Increased bicarbonate
o Hypochloremia (relative to sodium)
8
Q
Respiratory acidosis
A
- Lungs can’t efficiently get rid of CO2 (hypoventilation)
o Airway obstruction
o Impaired gas exchanged
o Problem with respiratory muscles or diaphragm
9
Q
Respiratory acidosis: result
A
- Increased pCO2 in blood
o Acute compensation occurs via intracellular buffers
o Delayed compensation (24h) occurs via the kidney
Increased renal excretion of H, retention of HCO3
See increased HCO3 and acidic urine
10
Q
Respiratory alkalosis
A
- Lungs get rid of excessive amounts of CO2 (hyperventilation)
o Anxiety
o Pain
o Fear
o Exercise
o CNS disease
o Hypoxemia
11
Q
Respiratory alkalosis: result
A
- Decreased pCO2 in blood
o Acute compensation occurs via release of H+ from intracellular buffers
o Delayed compensation via kidney
Decreased renal excretion of H+
See decreased HCO3- and alkaline urine
12
Q
What are the 4 questions to ask when trying to interpret?
A
- Is an acid-base disturbance present?
- What is the primary disturbance?
- Is there a secondary (compensatory) response?
- Does this make sense from the patient’s perspecitive?
13
Q
What are some tips to approach interpretation?
A
- Primary disturbances will occur in same direction as pH change
- Compensation occurs in opposite system and direction
- Over-compensation does NOT occur
- Can be an acid-base disorder even with a normal pH
- Mixed disorders are common
14
Q
Mixed acid-base disorders in small animals
A
- High anion gap metabolic acidosis and hypochloremic metabolic alkalosis
o Bicarbonate: low or high
o AG: increased
o Cl: decreased - *Ex. dehydrated vomiting patient
15
Q
Mixed acid-base disorders in young calf
A
- High anion gap metabolic acidosis and hyperchloremic (bicarbonate loss) metabolic acidosis
o Bicarbonate: low
o AG: increased
o Cl: decreased
16
Q
Chloride info
A
- Sodium and chloride typically travel together
o Change in free water=Na and Cl change proportionately - Acid base disturbances = Cl change is DISPROPORTIONATE to Na change
- *method: “eyeball results”
o Take the patient value subtracted from the lower reference interval
17
Q
What do you expect the urine pH to be under normal conditions with a metabolic alkalosis?
A
- Kidney wants to retain H+ and excreted HCO3-
o Urine pH=alkaline
18
Q
What is paradoxic aciduria?
A
- Kidney loses H+ into urine and retains HCO3-
- Urine pH=acidic
- Most often seen in ruminants
- *NEED TO HAVE: develops with prolonged metabolic alkalosis with hypochloremia and hypovolemia
19
Q
Paradoxic aciduria: dehydration
A
- Kidney prioritizes Na+ resorption
- Need to balance charge to maintain electroneutrality
- Cannot reabsorb Cl- if hypocholremic
- *thus cations are excreted (H+ > K+)
20
Q
When metabolic alkalosis predominates in a cat/do with GI signs, what do you need to do?
A
- Rule out a GI foreign body OR other cause of intestinal obstruction/upper GI pathology
