Clin Med - Adv. Diagnostics & Fluid Therapy Basics

pbhati17's version from 2017-03-03 01:28

Advanced Diagnostics

Question Answer
High SENSITIVITY means few false ___NEGATIVES. False negative means it really was positive but your test missed it. (N in sensitivity & in negatives) (Want a VERY SENSITIVE test if testing for HIV in blood donations, was the original example)
High SPECIFICITY means few false ___POSITIVES.
What is the math equation for sensitivity?The (TRUE POSITIVES) / (TRUE POSITIVES + FALSE NEGATIVES)
What is the math equation for specificity?The (TRUE NEGATIVES) / (TRUE NEGATIVES + FALSE POSITIVES)
So, something infects an animal & you want to see if it's what you think it is. What are the 2 WAYS/TESTS you can try to use to see if you were right?Detect the ANTIBODY or detect the PATHOGEN itself
Where do you find Abs in the body?Serum! THIS MEANS RED TOP TUBE!
Higher the titer means it is MORE ___POSITIVE FOR THE ANTIGEN/AB
Which is a more positive titer.... 1:4 or 1:300?1:300 (diluted it 300 times & you still can detect it? You are REALLY positive for that Ag or Ab)
What is immunodiagnostics?Detecting the AB!!
What are 2 ways you can tell the difference btwn exposure, infxn & Vx when doing immunodiagnostics?(1) PAIRED SAMPLES-usually do 2 samples, 2 weeks apart. Look for an ↑ in the titer. (Ex: exposure is common for X dz, but if the animal was actively infected w/ X, the titer would be 5-7xs higher than the exposure titer
(2) TYPE OF Ig-If the Ab from a Vx, the Ab would prolly be IgG ((it has memory from the Vx)
. If the Ab was from an infxn, there would be IgM (quick on the scene 1st Ab, IgG hasn't had time to form yet which means active infxn)
ELISA: what is the change you're looking for? What exactly is going on?Looking for a color change for a positive result (think SNAP test). There is an Ag coated plate/SNAP & you introduce serum.
WESTERN BLOT: What is the change you're looking for? What exactly is going on?Looking for a banding pattern. You run serum through a gel impregnated w/ w/ Ag
IFAT (fluorescent Ab): What is the change you're looking for? What exactly is going on?Looking for glowing, add serum to Ag coated slide.
ELISA: Ab or Ag detection?Ab detection
WESTERN BLOT: Ab or Ag detection?Ab detection
IFAT: Ab r Ag detection?Ab detection (can also be Ag! depends!)
"Culturing viruses" is called...?Virus isolation
What is a broad, non-specific way to detect pathogens?CULTURE THEM!
What does PCR do/detect? What is the caution & the downside of PCR?Detects the DNA of the PATHOGEN! Caution: very specific, you can't just "PCR for everything". Also, PCR might be able to detect DEAD organisms
PCR: Ab or Ag detection?Ag
Explain how you can use IFAT to detect antigens**COMERCIALLY PRODUCED ABs, NOT FROM THE Pt!! Get antigen sample from PTx, add the commercial Ab (ex: Rabies in the brain detection)
What is going on in immunohistochemistry?Take tissue (contains Ag) from Pt, add a stain containing commercial Ab to the tissue, see if it stains

Fluid therapy basics

Question Answer
Your total body water (TBW) is 60% of your body weight. Of that, what percent is in the ICF (intracellular fluid)? ECF?ICF=66% of TBW
ECF= 33% TBW
What are the 3 places which encompass the extracellular fluid?Intravascular, interstitial & transcellular
How much of the TBW (total body water) is intravascular?Blood vol is 8% TBW
Which is the largest component of the ECF?Interstitial
Which area of the ECF is starlings law affecting & what is the solute-vs-plasma balance?Starlings law is at most effect w/in the interstitial space (btwn cells) & the solutes & plasma are roughly at equilibrium.
Give some examples of transcellular ECF spacesSynovial, peritoneal, CSF, intraocular
Briefly explain Starling's lawWater follows solute yay! Slightly more involved definition is that there is hydraulic & oncotic pressure in both the capillary & in the interstitium. Wherever the solute is, the water will follow until there is equilibrium
What are the effective osmols of the ECF?Na+, Cl-, bicarbonate
What are the effective osmols of the ICF?K+, PO4-, ICF proteins (mostly fixed in the cell)
Chart on slide 7-don't have to memorize, understand the relationshipsInterstitial vs intracellular vs plasma values.... how they relate to ECF & ICF
What is tonicity regulated by? Explain in relation to a cellRegulated by effective osmosis! If the solution around a cell is isotonic (same tonicity/solute balance as outside) then the cell is normal. If the solution is hypotonic, (WATER FOLLOWS SOLUTE HEY!) then there is less solute out than in the cell, so the water moves in where there is more solute & the cell swells. If the solution is hypertonic, there is more solute out of the cell, so water flows out & the cell shrinks
Dehydration means there is hypertonicity where?In the ECF
Which fluid compartment bears the brunt of the fluid loss in dehydration?THE ICF! bc ECF inclds blood volume & body will ALWAYS try to preserve blood volume 1st.
What is the HALLMARK of dehydration?HYPERNATREMIA!


Question Answer
Things like fever/panting/lack of water can cz dehydration...what is the 1st response of the body to compensate?Central osmoreceptors are triggered to affect water consumption.
*Chart on slide 10-don't memorize, but understandHypovolemic thirst & osmotic thirst lead to trigger different paths in the body...end result is MORE DRINKING & LESS WATER LOSS
What’s the difference btwn dehydration & hypovolemia? Which is more worrisome?Dehydration is loss of body water. Hypovolemia is loss of body water & loss of electrolytes, which is a much bigger problem.
Is dehydration isotonic, hypertonic, or hypotonic? How about hypovolemia?DEHYDRATION: hypertonic-only water loss
HYPOVOLEMA: isotonic-loss of water & electrolytes
Which water compartment is most affected in dehydration? Hypovolemia?DEHYDRATION: ICF is affected (hypertonicity pulls fluid from ICF into ECF). HYPOVOLEMIA: the solution is still ISOTONIC (equal loss of water & electrolyte) so there is no gradient for water to follow, so the ICF fluid stays put & the loss is from the ECF
What are some czs of hypovolemia?Hemorrhage, GI loss via vomiting or diarrhea, 3rd space loss (such as the peritoneum), also severe burns or tissue injury.
↓ Blood volume czs a ↓ in what other 4 things?↓ venous return
↓ stroke volume
↓ cardiac output
↓ tissue perfusion
Which are the organs the body tries to preserve the BEST when there is hypovolemia? How about the LEAST?Brain & heart get all they need no matter what-skin & gut are the 1st to go (kidney is kinda a middleman)
↓ BP & vol lead to triggering which type of receptors? To lead to what 2 mechanisms? Which czs? (SEE SLIDE 14 FOR CHART)Baroreceptors (neural mechanism) leads to ↑ CO, as well as peripheral vasoconstriction leading to ↑ BP & ↓ venous reserve. There is also the endocrine mechanism, to release hormones (like angiotensin) which ↑ blood volume. The overall affect is homeostasis of ECF restored!
Explain the renin-angiotensin-aldosterone system (where everything comes from, what it does...)The liver produces angiotensin. If the kidney senses a ↓ in renal perfusion (via the JG cells), it releases renin. Renin acts on angiotensin to turn it into angiotensin I. THEN, the lungs & kidneys produce ACE (angiotensin converting enzyme) which converts angiotensin I into angiotensin II. ANGIOTENSIN II IS SUPER SUPER POWERFUL! Angiotensin II exerts effects (details on other card) which result in water & salt retention, increasing the effective circulating volume, which ↑ the perfusion of the kidney (thus JG cells) which provides the negative feedback for the system
What are some of the specific effects that angiotensin II has on the body?↑ sympathetic activity, ↑ aldosterone secretion → tubular resorption of Na+, Cl- & water (& loss of K+) (This is both a result of the aldosterone & also a direct effect of the angiotensin II), it triggers arteriolar constriction + raise in BP & affects the pituitary to secrete ADH to absorb more water from the tubules.
What is dysoxia?SHOCK
Progressive hypovolemia leads to dysoxia (shock) which is a result of which 2 pathological events in the body?(1) Inadequate oxygen (hypovolemia & cardiogenic)
(2) Mitochondrial dysfxn (endotoxic & septic)
What are some of the CS of hypovolemia? (An EMERGENCY situation)Tachycardia
↓ Pulse pressure
↑ Capillary refill time
↓ Jugular fill
Cold extremities
↓ Urine output
What is the MOST IMPORTANT/EMPHASIZED diagnostic test you must do for checking dehydration or hypovolemia?Body weight monitoring!!
List the diagnostic tests you'd use to determine dehydration or hypovolemiaBODY WEIGHT MONITORING
Lactate (anaerobic metabolism marker)
Central venous pressure (CVP)
Venous oxygen saturation

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