Fluids, Electrolyte, Water Balance

Exam 1, Dr. Wai

water

• the most abundant component of the body

• 50-70% body weight

total body water

• distributed into 2 compartments:

• extracellular fluid (ECF)

• intracellular fluid (ICF)

80%

infant TBW %

60%

male TBW %

50%

female TBW %

45%

• adult older than 60 years TBW %

• decreases with age

ICF

2/3 of TBW

ECF

1/3 of TBW

ISF

80% of ECF

IVF

20% of ECF

sodium (Na)

• the major determinate of ECF volume

potassium (K)

• the major determinant of ICF volume

142

sodium accounts for ___ mEq/L in plasma ECF

144

sodium accounts for ___mEq/L in interstitial Fluid ECF

135

Potassium accounts for __ mEq/L in ICF

milliequivalent

• mg x valence / atomic weight

• measure the chemical combining capacity

Basic Metabolic Panel (BMP or Chem7)

• Na

• K

• Cl

• CO2

• BUN

• Creat

• Glucose

Complete Blood Count (CBC)

• WBC

• Hgb

• Plt

• Hct

Anticoagulation labs

• PT

• PTT

• INR

milliosmole

• measure of the number of osmotically active ions or particles in a solution

• movement of water between the ICF and ECF largely controlled by osmolalaity

low, high

• water moves from areas of-__ osmolarity to one of _osmolarity

280-285 mOsm/L

• normal ECF osmolality

isotonic IV solutions

• 0.9% NaCl= Normal saline

• lactate ringers (LR)

154mEq/L

0.9% NaCl or normal saline sodium amount

130mEq/L

Lactated ringers sodium amount

Hypotonic IV fluids

• 0.45% NaCl or ½ NS

• 0.225% NaCl or ¼ NS

• 5% Dextrose or D5W

77 mEq/L

0.45% NaCl or ½ NS amount of sodium

38.5 mEq/L

0.225% NaCl or ¼ NS amount of sodium

0 (free water)

Dextrose 5% or D5W amount of sodium

hypertonic IV fluids

• 3% NaCl

• 23.4% NaCl

Lactacted Ringers

• 130- sodium

• 109- chloride

• 4- potassium

• 3- calcium

• 28- lactate

no change

• if you add 0.9% NaCl to ECF, what is the change in the ECF osmolality?

increase in ECF volume

• if you add 0.9% NaCl to ECF, what is the net effect in the ECF?

No change

• if you add 0.9% NaCl to ECF, what is the net effect in the ICF?

Decrease

• if you add D5W to the ECF, wha tis the effect on ECF osmolality?

Increase

• if you add D5W to the ECF, what is the net effect on ECF?

Increase

• if you add D5W to the ECF, what is the net effect on ICF?

Increase

• If you add 3% NaCl to ECF, what is the effect on ECF osmolality?

Increase

• If you add 3% NaCl to ECF, what is the net effect on ECF?

Decrease

• If you add 3% NaCl to ECF, what is the net effect on ICF?

fluid homeostasis

• occurs when required amounts of water and solutes are present in appropriate proportions within compartments

• input should equal output

sensible, insensible, excess

types of water loss

sensible water loss

• sweat- 100 ml/day

• feces- 100 ml/day

• urine- 1400ml/day

insensible water loss

• skin and lungs (evaporative)650-800ml/day

excess water loss

• fever

• warmer climate

• diarrhea

• vomiting

maintenance therapy

• replaces the ongoing losses of water (and electrolytes) under normal physiologic conditions via urine, sweat, respiration, and stool

replacement/resucitation therapy

• corrects any existing water and electrolyte decifits may be from gastrointestinal (GI) , urinary, or skin losses, bleeding, and thrid spacing

700-800

need to ingest ___ ml of water to maintain water balance

maintenance fluid replacement for children

• administer 100ml/kg for the first 10kg of weight, then 50ml/kg for the next 10kg plus 20ml/kg for every kg over 20kg

maintenance fluid replacement for adults

• 1500ml plus 20ml/kg for any increment over 20kg

• common max- 2400ml/day

acute fluid resuscitaiton

• intravascular fluid depletion can occur as a result of shock

• reduced cardiac function and organ hypoperfusion (decrease blood supply)

• signs and symptoms usually occur when 15% of blood volume is lost of shifts out of the intravascular space

acute fluid resuscitaiton signs and symptoms

• tachycardia (HR >100)

• hypotension (BP < 90)

• orthostatic changes in HR or BP

• dry mucous membrane

• decreases skin turgor

• reduced urine output

• dizziness

• improvement after 500-1000ml fluid bolus

acute fluid resuscitaiton goal

• restore intravascular colume and prevent organ hypoperfusion

0.9% NaCl or Lactated ringers

crystalloids recommended for rapid infusion for acute fluid resusuciation

when to choose colloid (albumin) over crystalloid

• 4-6L of fluid resuscitation failed or significant edema already present

antidiuretic hormone (ADH)

• arginine vasopressin (AVP)

• secreted by the posterior pituitary gland

• actions:

• regulates the rate of free water excretion

• increases permeability of the collecting ducts to reabsorb water

hyperosmolarity, hypovolemia

antidiuretic hormone (ADH) primary stimuli

ADH secondary stimuli

• shock or stress

• trauma

• operation

• pulmonary insufficiency

• anesthetic

• infection

• multi organ failure

• drugs, hypoglycemia, severe nausea

angiotensin II

• causes the kidneys to retain both salt and water

angiotensin II direct effect

• Na/H2O retention in the kidneys

• vasoconstriction of the efferent renal arterioles

angiotensin II indirect effect

• stimulates aldosterone secretion

• aldosterone then increases salt and water reabsorption by the tubules

aldosterone

• most potent mineralcorticoid -= 90% of the body’s activity

• main action: stimulate Na-K-ATPase channels in the collecting ducts

• increases NA and H2O reabsoprtion

• K and H urinary excretion

4 factors regulating aldosterone

• increase ECF potassium → increase aldosterone secretion

• increase in RAAS system→ increase aldosterone secretion

• increse ECF sodium → slight decrease in aldosterone secretion

• ACTH secretion from the anterior pituitary is required for aldosterone secretion

increase

• increase ECF potassium → __ aldosterone secretion

increase

• increase in RAAS system→ increase aldosterone secretion

ACTH

• required for aldosterone secretion

cortisol

• major glucocorticoid

• released from adrenal glands in response to stress, low blood pressure, low blood sugar

• significant amount of mineralcorticoid activity

• increases NA and water retention → increases blood pressure

catecholamines

• ex: norepinephrine, and epinephrine

• potent vasoconstrictors that can reduce renal blood flow

• increase Na and H2O reabsorption by:

  • direct stimulation of proximal and loop Na transport

  • increased arteriolar resistance/ renal vasoconstriction

  • activation of RAAS (secondary effect)

• drives potassium intracellularly

atrial natriuretic peptide (ANP)

• counterbalance RAAS system

• produced primarily by the atrium of the heart

• stimulus

  • increased atrial wall stretching- MAJOR

  • endothelin, ADH, and catecholamines

• antagonizes the effects of angiotensin II

• blocks vasoconstriction, inhibits Na reabsorption, and aldosterone secretion

• increases renal excretion of Na and water

• vasodilates arterioles and relaxed mesangial cells

• increases vascular permeability

ADH, angiotensin II, aldosterone, cortisol, catecholamines

which hormones increase water reabsorption?

angiotensin II

which hormone is stimulated by renin release, causes renal retention of sodium/water, and stimulates aldosterone release?

Depletion signs/symptoms

• weight loss

• diminished skin turgor

• dry mucous membranes

• orthostatic hypotension and tachycardia

• severe- disorientation and overt shock

Depletion Labs

• increased hematocrit

• increased BUN and creatinine

overload signs and symptoms

• weight gain

• dyspnea on exertion, orthopnea

• edema

• ascites

• anascara