Lecture 12 CNS Toxicants II - Part 1 Flashcards
- The use of strychnine and fluoroacetate is ______
- A few ___ states still use them
- Fluoroacetate is widely used in _______ and _____ __________
- Most _________ are banned in US and Canada
- ____ re-approved for malaria control by WHO in 2006
- The use of strychnine and fluoroacetate is
limited - A few US states still use them
- Fluoroacetate is widely used in Australia and New Zealand
- Most organochlorines are banned in US and Canada
- DDT re-approved for malaria control by WHO in 2006
What are the DIRECT causes of sodium toxicosis?
What happens to the ECF as a result?
- Direct Na+ toxicity: excess salt intake
- ECF Na+ content increases relative to the free water content
What are the INDIRECT causes of sodium toxicosis?
- Indirect toxicity: water deprivation
- Free water in ECF is lost without compensatory decrease in Na+ concentration
What is the main issue with sodium toxicosis?
Free water deficit
What is the treatment goal in a case of sodium toxicosis?
- Correct free water deficit
Body water - Total body water is 60% of body weight
- This is the 0.6 in the free water deficit (FWD)
calculation equation - 40% (2/3) intracellular; 20% (1/3) extracellular
What do treating a hypernatremic patient require?
- Treating hypernatremia requires knowledge of the degree of elevation of serum Na+
concentration
Hypernatremia may be present with?
hypovolemia, euvolemia or hypervolemia
What is the initial step in evalutaing perfusion deficits?
- Capillary refill time, heart rate, pulse strength, blood pressure
What do you treat first?
- Treat the volume deficit first –> Correct the free water deficit
What are the three ways to evaluate the free water deficit?
Over how long should Na+ levels be lowered?
- Na+ levels should be lowered no faster than 0.5 - 1 mEq/h to avoid development of edema
What is recommended to correct a free water deficit? Explain why.
- Hypertonic saline is recommended –> Reduces incidence of iatrogenic cerebral edema
Na+ levels of the parenteral and oral fluids should closely match ?
Explain why.
serum Na+ levels
* Prevents movement of water into CSF
* Physiologic saline contains 154 mEq/L Na+. In clinical cases serum
Na+ levels are >160 mEq/L so additional Na+ is required
* If Na+ levels are not known initial IV fluid should contain 170
mEq/L Na+ and should be decreased as clinical signs improve
Once Na+ levels of the parenteral and oral fluids match up, what should be done next?
Na+ levels in fluids should then be decreased as clinical signs improve
Watch videos and fill in treatment file on brightspace
Acute (severe) hypernatremia that develops in minutes to hours, e.g., from a massive salt
overdose, causes the brain to _______ –> can cause _______ of blood vessels resulting in ______________ hemorrhage.
If the hypernatremia is sustained (e.g., > ___ hours), there is an adaptation of brain cells in which an increase in _________ and organic _______ occurs.
shrink, rupture, intracranial, 48, electrolytes, osmolytes
Electrolytes and organic osmolytes draw water _______ the brain cells which partly corrects the
initial cell ______, but ____ osmolality persists.
The rapid correction of hypernatremia results in _______ _____ because water _____ by brain
cells exceeds the ________ of accumulated electrolytes and organic osmolytes.
The cerebral edema causes the serious signs of CNS impairment seen when hyponatremia is
corrected _______.
In contrast, slow correction of the hypernatremia reestablishes normal brain osmolality without
causing _______ _______ because this allows the dissipation of _________ electrolytes and
organic osmolytes to keep pace with water ________.
into, shrinkage, high, cerebral edema, uptake, dissipation, rapidly, cerebral edema , accumulated, replacement
