Hypothermia Intricacies

[Rangat]

2 Questions i was asked in my viva/oral exam, that I can't find info on:

*Both Hyper-and-Hypothermia may result in hypovolaemia. Why?
Hyper I can understand, but all I know is in hypothermia two things occur:

-Fluid shift into Intracellular space (I dunno why?)
-Cold diuresis
Its either caused by peripheral vasoconstriction, resulting in a higher renal pressure, stimulating pressure diuresis.
Or caused by the cold decreasing the secretion of ADH by the neurohypophesis, thus less filtrate reabsorbed.
Or by cold action on the renal cells itself.


So I would guess it is one of these, but WHY does it happin? HOW does it work?




*Why does the ECG changes seen in hypothermia occur? (Osborn/J waves & Fibrillation)

I really don't have any clue? Not in any of my books.




I have provoked much academic masturbation of my peers, but nobody has had an epiphany yet. Any help?:sad:

 

[MMiz]

I'm clearly out of my league, and I'm not sure if this will help, but in my limited research I keep seeing:

Systemic hypothermia prolongs repolarization usually with a distinctive convex elevation of the J point.

I'm not sure what the means, but it may be a starting point.

 

[So. IL Medic]

2 Questions i was asked in my viva/oral exam, that I can't find info on:

*Both Hyper-and-Hypothermia may result in hypovolaemia. Why?



So I would guess it is one of these, but WHY does it happin? HOW does it work?




*Why does the ECG changes seen in hypothermia occur? (Osborn/J waves & Fibrillation)

I really don't have any clue? Not in any of my books.




I have provoked much academic masturbation of my peers, but nobody has had an epiphany yet. Any help?:sad:

Hypovolemia in hypothermia - you're headed in the right direction. The cold injury causes the nephrons of the kidney to stop reabsorbing water plus ADH levels fall. Also, the body sometimes reacts to the shunting of blood to the triunk as hypervolemia and stimulates diuresis that way. Massive diuresis results. Second, fluid flows into the interstitial space or extracellular space furthering loss of volume. That is one possibility.

The other is the danger of hypovolemia occuring during rewarming. This is easier to visualize. Hypothermia produces peripheral vascular constriction. Warming causes dilation. Suddenly the container becomes bigger than the volume and more hypovolemia.

For cardiac changes - think about it. Reduced circulation, reduced O2, reduced clearance of CO, CO2, metabolites, etc. This reduces the abilitity of calcium and potassium pumps and channels. That in turn screws up the electro-chemical propagation of signals in the heart giving you EKG changes.

 

[Rangat]

Appreciated...B)

 

[So. IL Medic]

Anytime