Fluid is in both compartments 50-60% of body weight ¾ of ECF ¼ of ECF
Intravascular Fluid or Plasma (1/4 of ECF)
Necessary for BP Maintenance
Maintenance of Proportional Distribution
Protein content of blood (Serum proteins- globulin and albumin
Integrity of blood vessels linings
Hydrostatic pressure inside blood vessels
Concentration of dissolved substances expressed in mOsm/L (Normal 280-300)
Movement of Body Fluids
Concentration- solvent moves to make concentrations even although volume is not.
Redistributing - high to low to make even
Energy requirement for selective admission
Movement of fluid through semipermeable membrane
Concentration controls- solvent moves to make concentrations even although volume is not
Filtration Pressures in a Capillary
Problem Examples: Edema Congestive heart failure
Diffusion - movement of solutes against a concentration gradient; tries to to balance cations + with anions -
Requires energy from metabolism to move larger or uneven substances across cell membranes
Glucose needs insulin to enter cell
Active Transportation of Glucose
Na-K Pump: For every molecule of ATP, 3 molecules of Na move to outside of cell and 3 molecules of K move inside the cell
Factors Affecting Fluid & Electrolyte Movement
Osmotic Pressure and Tonicity
Osmolality and Tonicity
Osmolality (Kg) and osmolarity (L) are determined by the solutes (mainly Na) in the ECF
Abnormalities tell us that there are problems with water regulation in the ECF.
Tonicity is the force that the ECF solutes (mainly Na) have to pull water into the ECF.
(Na, glucose, mannitol, sorbitol are effective osmoles.)
Osmosis and Tonicity Na is the main determinant of plasma tonicity . Thirst and ADH release Swelling of cells
Problem Examples: Edema Congestive heart failure
Tonicity HYPO 0.45% saline (1/2 normal) Moves fluid into cells
Tonicity ISO Same osmolarity as plasma 0.9 % saline (Normal saline) – no fluid shift
Tonicity HYPER 3% saline Pulls fluid from cells
Electrolytes + - - - - - + + + +
Sodium - Na 135-145mEq/L
Potassium - K 3.5-5.0 mEq.L
Calcium - Ca 4.5-5.5 mEq/L
Magnesium - Mg 1.5 - 2.5 mEq/L
Chloride - Cl 90-110 mEq/L
Bicarbonate – HCO 3
Arterial 22-26 mEq/L
Venous 24-30 mEq/L
Sodium and ECFV
The total amount of Sodium in ECF is the major determinant of the size of the ECF Volume
Na increases = ECFV increases until ECF ‘volume overload’ results (edematous states)
CHF, Cirrhosis of the liver, nephrotic syndrome
Pleural effusions, pulmonary edema, ascites
Na decreases = ECFV decreases eventually leading to ‘volume depletion’ manifested by poor skin turgor, tachycardia, orthostatic hypotension
Kidney receptors sense changes in renal perfusion causing renin-angiotensin system to retain sodium in kidney.
Volume receptors in great veins sense filling and release atrial natriuretic factor that promotes Na excretion.
Pressure receptors in aorta and carotid sinus activate sympathetic NS to retain Na .
Water ALWAYS follows Na
Therefore when ECFV increases, these mechanisms are activated to increase Na excretion; and conversely, if ECFV decreases, the same means promotes Na retention.
Water Regulation ( Hypo- and Hyper-Natremia are always a problem with water, not Sodium)
Osmolality increase in ECF -> Thirst
Renal responsiveness to tonicity
Adequate delivery of water and solutes to glomerulus of kidney ( Problem: Early reabsorption of water due to volume depletion or edematous states )
Water conservation mechanisms in kidney (Can be overridden by diuretics either in loop or in distal tubule.
ADH in response to tonicity changes, i.e., Na, or in response to volume changes (Problems: SIADH and DI)
Both Thiazides and Loop diuretics block Na reabsorption and cause decrease in ECF, too.
Loop cause greater loss of Na but equal water, but thiazides lose less water than Na and can cause hyponatremia .
Manifestations of Fluid, and Electrolyte Imbalances
Imbalances of Intake and Output and Body Weight
Changes in Mental Status
Changes in Vital Signs
Abnormal Tissue Hydration
Abnormal Muscle Tone
Signs and Symptoms of Dehydration *Poor skin turgor (tenting of the skin of the back of the hand is common in normal geriatric patients b/c of age-related skin changes A recent history of poor oral intake and/or a documented weight loss are probably better warning signs of dehydration in geriatric residents.
Loss of appetite
Dry mouth or eyes
Burning sensation in stomach
Dark urine with strong odor
Advanced Dehydration Early Dehydration
Teaching depending upon setting
Oral fluid increase
Oral fluid restriction
Diet or supplement
Renal failure, chemoTx, enemas containing Malnourished, alcohol withdrawal, phosphate- binding antacids Muscle, RBC’s, CNs, w/ Calcium in bones and teeth 1.7-4.6 Phos Phosphate Maalox and Milk of Magnesia in patients with renal failure Diarrhea, vomiting, NG Suction, hyper aldosteronism Muscle, RBC’s and CNS, metabolism 1.5-2.5 Mg Magnesium Mult. Myeloma, thiazide diuretics, malignancies, Chronic renal failure, Vit D deficiency, pancreatiti,s, loop diuretics, diarrhea hyporparathyroidism Transmission of nerve impulses, cardiac contractions, bone, blood clotting 4.5-5.5 Ca Calcium Acidosis Renal disease K containing drugs K salt substitute GI Losses – diarrhea, vomiting, duretics, diaphoresis Major ICF cation; cellular and metabolic functions including cardiac rhythms 3.5-5.0 K Potassium High fever, heatstroke due to insensible water loss, diabetes insipidus GI Losses Diuretics, burns, wound drainage Maintains concentration of ECF 135-145 Na Sodium Hyper Causes Hypo Causes Function Normal Value Symbol Name Serum Electrolytes
Neck Vein Distention
Central Venous Pressure
Pulmonary Artery Pressure
Laboratory and Diagnostic Tests
Central Venous Pressure or Jugular Venous Distention
Normal Pattern Identification
Objective Data—Physical Assessment
Intake and Output
plasma expander Isotonic (308 mOsm/L) 10% Dextran 40 in 0.9%NS closely resemble the electrolyte composition of normal blood serum and plasma; will need additional K; does not provide calories or free water; used to treat losses from lower GI tract and burns. Isotonic (273 mOsm/L) Lactated Ringer’s Solution provides free water (hypotonic) to the extracellular and intracellular spaces, as the dextrose is quickly metabolized; promotes renal elimination of solutes; treats hypernatremia; does not provide electrolytes; one liter is 170 calories Isotonic (252 mOsm/L) D5W - 5% Dextrose in water to treat fluid volume deficit; for daily maintenance of body fluids and nutrition; basically the same as NS, except provides 170 calories per liter Hypertonic (559 mOsm/L) D5NS - 5% Dextrose & 0.9NaCl to promote renal function and excretion; basically the same as .45NS except provides 170 calories per liter Hypertonic (406 mOsm/L) D5 1/2 NS - 5% Dextrose & 0.45NaCl assists with renal function; provides free water, Na and Cl.; replaces normal hypotonic daily fluid losses- assists with daily body fluid needs, but not with electrolyte replacement or provision of calories. Hypotonic (154 mOsm/L) 1/2 NS - 0.45%NaCl replaces NaCl deficit and restores/expands extracellular fluid volume; the only solution that may be administered with blood products --does not provide free water that causes hemolysis of red blood cells Isotonic (308mOsm/L) NS - 0.9% NaCl Usage and Limitations Osmolality Solution
Third Spacing: Loss of fluid into a space that cannot contribute to ICF/ECF equilibrium S&S: Urine output decreases Increased heart rate Decreased BP Decreased CVP Increased body weight Edema I & O imbalance Causes: Burns Ascites Peritonitis Bowel obstruction Massive bleeding into joint or body cavity
Factors Affecting Fluid, Electrolyte, and Acid-Base Balance
Fluid and Food Intake
Fluid and Electrolyte Output
Acid Base Balance Two systems work to maintain correct pH. Respiratory System by adjusting respirations. Metabolic system by adjusting serum HCO3
Acid Base Balance
Acidosis pH < 7.4 Increased paCO2 Decreased HCO3
pCO2 = 35-45 HCO3 = 22-28
Hypoventilation for any reason
Paralysis of respiratory muscles
Cardiac Arrest – Code
Lactic Acidosis from heavy exercise
Drugs – EtOH, ASA
Alkalosis pH > 7.4 Decreased CO2 Increased HC03
Hyperventilation from any cause
Too high ventilator settings
Hypokalemia OR Hypercalcemia
Drugs – Steroids, diuretics, NaHCO3
Easy Read of Blood Gases
<7.4 = Acidosis; > 7.4 = alkalosis
Which of the following parameters matches the pH?
CO2 or HCO3?
High C02 is acid; low CO2 is alkaline- respiratory
High HCO3 is alkaline; low HCO3 is acid - metabolic
Matching parameter + pH direction is diagnosis! If both parameters match, then it is a combined _____; if opposite parameter is abnormal, compensation is occurring.