Acid Base Flashcards
what are the 3 big “pools” of fluid in the body?
intracellular fluid, interstitial fluid, and the plasma
what are the four ways the body naturally loses water?
feces, urine, sweat, lungs
what does aldosterone respond to, and what does it cause?
low blood pressure triggers the RAAS system to release aldosterone which causes renal sodium and water retention to increase blood pressure again
what causes ADH release and what does it do?
increase in extracellular osmolarity causes ADH release, which increases thirst and increased water retention
what are the 3 broad ways in which body water can change?
- increase in TBW: excess fluid intake or excessive fluid therapy, maybe inappropriate ADH release
- decrease in TBW: decrease fluid intake, increase fluid losses (diarrhea or vomiting, sweating, etc)
- redistribution: from ICF to ECF, increase in hydrostatic pressure or decreased oncotic pressure (think edema), shock, or 3rd space loss
what are some things we use in clinic to assess total body water?
clinical signs!!! Hct, TP, USG
____ is the most important osmotically effective solute in the ECF
sodium
____ is interpreted in conjugation with patient’s hydration status
sodium
what are the 3 types of dehydration in relation to Na+?
- hypernatremic/hypertonic dehydration: mainly losing water
- normonatremic or isotonic dehydration: equal loss of water and Na+
- hyponatremic or hypotonic dehydration: mainly losing electrolytes
what are three ways in which you get can a decrease in total body H2O?
- water deprivation/inadequate water intake
- pure water loss (panting, hyperventilation, diabetes insipidus)
- water loss moreso than Na loss, osmotic diuresis
what are two ways you can get an increased total body Na+?
- iatrogenic: giving sodium containing IV fluids
- increased sodium intake without concurrent water intake, salt poisoning
what is the most common rason for a hyponatremia?
- excessive loss with continued water intake:::
- GI loss (vomitting, diarrhea, sequestration)
- renal loss (addisons, prolonged diuresis)
- cutaneous loss (sweating)
- third space loss (pleural or peritoneal effusion)
what are two other less common reasons for hyponatremia?
- excessive H2O like with edematous disorders like CHF
- shifting of water from ICF to ECF like with hyperglycemia and a change in osmostic gradient
what are some reasons for a hyperchloremia?
- similar causes to hypernatremia
- hyperchloremic metabolic acidosis (normal anion gap, alimentary loss of bicarb or renal loss of bicarb)
what is pseudohyperchloremia?
when you give KBr and the machine mistakes Br for Cl so it’s essentially a “fake” hyperchloremia
what are some causes for hypochloremia?
- similar causes to hyponatremia
- hypochloremic metabolic alkalosis (loss or sequestration of Hcl like vomitting, displaced abomasum, GI obstruction, bicarb increases to compensate and maintain eletroneutrality)
is most of K in ICF or ECF?
ICF
potassium is regulated via what hormone?
aldosterone, promotes renal K excretion
translocation of K+ into cells from ECF to ICF depends on
insulin and catecholamines (like epinepherine)
what is pesudohyerkalemia?
when there is a thrombocytosis and the sample is left out for a long time and the K from the platelets leak into the serum, creating a hyperkalemia that isn’t “true”. OR it can be a breed thing where the RBCs have K that undergo hemolysis and leaks into the plasma as well.
what is the most common cause for hyperkalemia?
- decreased renal excretion (renal failure, UT obstruction, addisons disease)
- rare, but giving potassium rich fluid
what are some less common reasons for hyperkalemia?
- shifting from ICF to ECF with tissue necrosis (rhabdo in horses) or diabetes mellitus
what are some causes for a hypokalemia?
decreased total body potassium like with anorexia, increased renal excretion, GI loss, or cutaneous loss
the principle regulators of acid base balance are whom????
lungs and kidneys
what is the main respiratory acid?
CO2
hyperventilation causes
alkalosis because you’re breathing off more CO2, which increases pH
hypoventilation causes
slooowww=acidooooosis
retaining CO2, decrease in pH
what are the primary acid base disturbances?
resp acidosis: increase CO2
resp alkalosis: decrease CO2
met acidosis: decrease bicarb
met alkalosis: increase bicarb
what are some causes of hypoventilation/sloooow acidooooosis?
pulmonary disease like pneumonia, asthma
anesthesia
CNS depressant drugs
what is the compensation for respiratory acidosis?
metabolic alkalosis: kidneys will excrete H+ in exchange for Cl- and conserve bicarb
what are some causes for hyperventilation?
pain, stress/anxiety, extreme exercise, overheating
what is the compensation for resp alklalosis?
met acidosis: renal excretion of bicarb in exchange fo Cl- and retain H+ ions
what are two mechanisms you can get a metabolic acidosis?
- a gain of acid (bicarb titrating out excess acid)
- true loss of bicarb, diarrhea or kidney loss, etc
what are the LUKE acids?
lactic acid
uremic acid
ketone
ethylene glycol
how do you tell if you have a gain of acid or a true loss of bicarb in regards to a metabolic acidosis?
look at the anion gap! if anion gap is increased, it means there is a gain of acids (LUKE), and if it isn’t, it is a true bicarb loss!
how do you calculate anion gap?
anion gap= (Na + K) - (Cl + HCO3)
what are two reasons for a met alkalosis?
- loss of acid/H+ (bicarb not being used up, like with vomiting)
- gain of bicarb
with a disproportionate hypochloremia, why is there an increase in bicarb?
because the HCl can’t met up with the bicarb! due to obstruction look at the diagrams idk how to explain it
what are the words for increased and decreased blood pH?
increased: alkalemia
decreased: acidemia
for a blood gas analysis, what kind of sample do you want?
an arterial sample, especially when evaluating oxygentation
Cl- always needs to be assessed in relation to changes in
Na!
in regards to Cl- on biochem, what is a proportionate change and what is a disproportionate change?
proportionate change: loss or gain of free water or concurrent gain/loss of both electrolytes
disporportionate change: where the change in Cl- is because it is balancing something else out, like when bicarb goes down, chloride goes up and visa versa
an ______ is present if SID is decreased
an _____ is present if SID is increased
acidosis
alkalosis
if SID is more than 35, then
if SID is less than 30, then
- probale alkalosis
- probable acidosis
what is the equation for super quick SID assessment?
SID= Na - Cl
only use it to look for presence of an alkalosis on biochem
compensation takes how long? metabolic vs respiratory?
metabolic: a few days
respiratory: minutes
true or false: you cannot have a mixed primary respiratory alkalosis (decrease CO2) and a primary respiratory acidosis concurrently (increase in CO2)
true, it is physiologically not possible
