Fluid, Electrolytes and Acid-base Flashcards
The anion gap is defined as which of the following?
a. The difference between sodium and potassium
b. The combination of all electrolytes
c. The difference between cations and anions
d. The difference between osmolarity and osmolality
C
What is the replacement volume for a 17^kg dog that is 7% dehydrated?
a. 540^mL
b. 1190^mL
c. 2420^mL
d. 119^mL
B
Which mineral helps with cellular regulation of Na, K, and Ca and should be examined in cases of refractory hypokalemia and hypocalcemia?
a. Calcium
b. Manganese
c. Magnesium
d. Phosphorus
C
What percentage of total body water is contained within the intracellular space?
a. 1/3
b. 2/3
c. 1/4
d. 3/4
B
Which of the following is not an example of an electrolyte?
a. Calcium
b. Magnesium
c. Oxygen
d. Phosphate
C
Which is the most abundant intracellular cation?
a. Sodium
b. Potassium
c. Magnesium
d. Calcium
B
The ability of a substance to make water move across cellular membranes is referred to as what?
a. Osmosis
b. Osmolality
c. Tonicity
d. Diffusion
C
According to Stewart’s strong ion approach to acid–base analysis, hyponatremia and hyperchloremia result in which metabolic condition?
a. Metabolic acidosis
b. Respiratory acidosis
c. Metabolic alkalosis
d. Respiratory alkalosis
A
Which of the following is a weak acid buffer?
a. Cl-
b. Na+
c. Albumin
d. Lactate
C
What is the total number of solutes per liter called?
a. Osmolarity
b. Osmolality
c. Tonicity
d. Diffusion
A
Interstitial oedema
Increased fluid within the interstitial spaces and broadly a result of one of the following
- Hypertension
- Hyproteinaemia
- Increased microvascular permeability
- Impaired lymph flow
- Inflammatory oedema
Oedema results in
Impaired oxygen delivery to the tissues and disrupts cellular functions
Major ECF cation
Sodium
Major Intracellular anion
Phophate
Even small fluctuations within reference range of sodium can be detrimental, true or false.
True
Effective osmoles
Those that are unable to pass freely across cellular membrane and contribute to osmotic pressure i.e. Na, K
Ineffective osmoles
Those that can pass freely across cellular membranes i.e. H2O
Low circulating volume triggers what response
RAAS
Preservation of H2O and Na to increase IV vol
increased ADH release and thirst to increase free water intake which may lead to hyponatraemia (and therefore a decrease in osmolality).
Free water deficit calculation
((Na, current / Na, normal) - 1) x (0.6 X BW)
Causes of hypernatraemia
Vomiting & Diarrhoea
PU
Water withheld
Activated charcoal
Osmotic diuresis (i.e. mannitol)
Diabetes insipidus
HTS
Salt water ingestion
Diet
Severe hypernatraemia
> 180mmol/L and may result in clinical signs
Neuro: ataxia, seizures, obtundation, heap pressing, coma, death
Cells: shrink as water moves out of the cell (hyperosmolar ECF)
Treatment of hypernaatraemia
Increase FW via hypo-osmolar fluids
Correct no quicker than 0.5-1mEq/kg/hr
Hyponatraemia
Severe retention of FW.
The body may sense low circulating volume causing ADH to be released and increased water and salt reabsorption.
Considered severe <120mEq/L and causes cellular swelling as water enters cells > cerebral oedema and increased tissue hydrostatic pressure.
How much potassium is located within the cell compared to ECF?
140mEq/L compared to 4mEq/L
Hypokalaemia and hyperkalaemia limits
<3.5mmol/L
>5.5mmol/L
Conseuqences of low K
Metabolic: glucose intolerance, insulin form B-cell impaired
Neuromuscular: weakness, ventroflexion, hyperpolarised myocytes
Renal: CKD
Cardiovascular: prolonged action potential, AV dissociation, VT, decreased ST segment, prolonged QT
Treatment of low K
CRI/Supplementation based on severity
Not to exceed 0.5mEq/kg/hr but in very severe cases may have short period of 1-1.5mEq/kg/hr
- Avoid bicarb and insulin until K normalising (at least 3.5)
Treatment of high K
Transcellular shifting: insulin, glucose & terbutaline
IVFT
Relieving urinary obstruction
Dietary adjustment
ACE inhibitors
Mannitol/diuretics
+- bicarb
10% CaGlu
Dialysis
Cardiac findings with high K
Atrial standstill
Bradycardia ++
Due to long depolarisation and repolarisation of myocardial conduction system
Cardiac findings with high K
Atrial standstill
Bradycardia ++
Due to long depolarisation and repolarisation of myocardial conduction system
iCa
Mediates acetylcholine release during neuromuscular transmission and also stabilises nerve cell membranes
What hormones/metabolites are involved in Ca regulation?
Parathyroid hormone
Vit D metabolites
Calcitonin
What samples should be avoided when testing Ca
EDTA
Oxalate
Citrate
- heparinized serum sample ideal
Signs of hypercalcaemia
PU/PD
Anorexia
Constipation
Letahrgy & weakness
Ataxia
Obtundation/coma
Twitching/seizures
Arrhythmias
Treatment of hypercalcaemia
Remove underlying cause
IVFT
Diuretics
Glucocorticoids
Bicarb
Pamidronate/biphosphamates
Clinical signs of low iCa
Bradycarida (decreased inotropy & chronotropy)
‘itchy’ face
Neuro changes
Cramping lethargy
Myocardial failure
Respiratory arrest
Treatment of low iCa
Ca IV (NEVER SQ)
Calcitriol
Magnesium homesostasis
Absorbed from the jejunum and ileum of the small intestine and reabsorbed by the LOH. The kidneys are the main regulator of Mg
Clinical signs of low Mg
Arrhythmias (tachy)
Neuromuscular weakness
Increased acetylcholine release
Decreased K, Na, Ca
Enhanced digoxin uptake Increased
Treatment of low Mg
Milder cases will resolve with therapy of underlying disorder
Can supplement orally or IV.
- IV = 30mg/kg or 0.15-0.3mEq/kg over 5-15min (life-threatening VT)