4. Hydration Flashcards
How much of the body is water? in adults, in neonates?
60% in adults, 80% in neonates
What is the distribution of body water?
66 ICF
33 ECF
5 in blood vessels
List the maintenance rates for adult k9, feel, sm pediatric, LA adult, LA pediatric
Adult k9 40-60ml/kg/day
Adul fel 50 ml/kg/day
SA ped 80-120 ml/kg/day
LA adult 40ml/kg/day
LA ped 80ml/kg/day
What is overhydration?
water intoxication
caused by iatrogenic, endocrine problems (inc ADH), behavioural overconsumption
Pathological changes - inc volume in blood vessels - dec oncotic pressure + osmotic pressure in blood vessels - fluid leaves blood ves enters interstitial space - dec osmotic press in interstate space - fluid enters cells
What are the pathological effects of overhydration?
ic demand on heart - inc water added to blood vessels inc BP
diuresis - inc blood flow thru kidneys inc urine
Pulmonary hypertension - fluid enters in lungs and pleural space(pulmonary edema- inc fluid in lungs)(pleural effusion - fuid in pleural space)
Cerebram edema + brain compression - ic water causes con of NA to drop, dec osmotic pressure in interstate space
cerebral edema - swelling excess fluid in brainw
what are the clinical signs of overhydration?
inc HR, BP, RR, urination
dyspnea
neurological signs - headache, ataxia, tremors, central blindness, seizures, coma
Which patients are at inc risk of overhydration?
heart, kidney failure
endstage liver disease
small animals
how do you treat overhydration
stop any fluids, diuretics, correct any underlying endocrine condition
what is dehydration?
greater water loss and intake. Neg fluid balance. reduces both circulating fluid and amount of interstitial tissue fluidwh
What are the causes of dehydration?
dec fluid intake - any form of water deprivation, drinking snow
Inc losses - lactating, athletics, hot weather, hyperthermia, V/D, renal losses, iatrogenic, loss of bood/plasma
What is oncotic pressure
affected by amount of soluble proteins in the blood vessels, albumin
what is osmotic pressure
based on conc of electrolytes, sodium
How can you diagnose dehydration?
- history
- CRT, MM, skin tent, HR, acute weight loss, tachycardia
- diagnostic tests - PCV, inc total proteins
What can you find/see with <3% hydration
sublinical, no PE signs, changes appear on testing (PCV, total proteins)
tx - drink more
What can you find/see with 3%-5% dehydration?
Mild - often sublinical, if clinical: lethargic, MM texture, weight change, changes on testing
tx oral fluids
what can you find/see with 5%-8% dehydration>
moderate - weight loss, lethargic, prolonged CRT, tacky mm, mild skin tent, clearly seen on tests
tx. iv fluids
What can you see/find with 8%-10% dehydration
marked - weight loss, lethargic to depressed, prolonged CRT, tacky to dry MM, skin tent, mild tachycardia, seen on tests
tx. iv fluids and correct electrolytes
what can you see with 10%-12% dehydration
severe - significant weight loss, depressed, dry MM, skin tent, suken eyes, cool extremities, tests show other changes to electrolytes and other organ func
tx. iv fluids and organ supporth
what can you see with >12% dehydration?
moribund - shock and dying
tx. shot fluids, possible cpr
How do you calculate dehydration?
% dehydration = (normovolemic weight in KG) - (weight when dehydrated in kg) x 100 divide by (normovolemic weight in kg)
EX. 5.47kg - 5.23 divide by 5.47 = 4.4% dehydrated
How do you calculate deficit?
Deficit volume in mls = (% dehydration) x (patients weight in kg) x 1L/1kg X 1000ml/1L
1 kg = 1L
What is the pathology associated with dehydration?
damage related to dec BP - dec tissue perfusion, cells/tissue less O2, nutr. delivery, dec removal of metab waste products
Kidneys + intestinal mucosa affected first (kidneys receive most blood flow)
Changes in electrolyte conc - hypernatremia - inc NA conc causes body water to shift compartments
metab acidosis
