Fluid, Electrolyte Fluid, Electrolyte and and
Acid-Base BalanceAcid-Base Balance
Total Fluid Volumes Total Fluid Volumes by Age and Sexby Age and Sex
0
10
20
30
40
50
60
70
80
90
PrematureInfant
Newborn Child 1-12 Puberty-39 Male
Puberty-39 Female
40-60Male
40-60Female
>60 Male >60Female
Normal Water Balance Normal Water Balance
I. Intake:
Fluid ingestion Fluid ingestion 60% 60%
Foods Foods 30% 30%
Metabolism Metabolism 10% 10%
II. Output:
Urine Urine 60% 60%
Sweat Sweat 8% 8%
FecesFeces 4% 4%
"Insensible" loss "Insensible" loss 28% 28% (skin, lungs)(skin, lungs)
Fluid CompartmentsFluid CompartmentsFluid CompartmentsFluid Compartments
IntracellularIn
trav
ascu
lar
Intr
avas
cula
r
ExtracellularExtracellular
InterstitialInterstitial
Intracellular
Fluid is in both compartments 50-60% of body weightFluid is in both compartments 50-60% of body weightFluid is in both compartments 50-60% of body weightFluid is in both compartments 50-60% of body weight
¾ of ECF
¼ of ECF
Intravascular Fluid or PlasmaIntravascular Fluid or Plasma(1/4 of ECF)(1/4 of ECF)
1.1. VolumeVolumeNecessary for BP MaintenanceNecessary for BP Maintenance
2.2. Maintenance of Proportional DistributionMaintenance of Proportional DistributionProtein content of blood (Serum proteins- globulin Protein content of blood (Serum proteins- globulin and albuminand albumin
Integrity of blood vessels liningsIntegrity of blood vessels linings
Hydrostatic pressure inside blood vesselsHydrostatic pressure inside blood vessels
3.3. OsmolarityOsmolarityConcentration of dissolved substances expressed in Concentration of dissolved substances expressed in mOsm/L (Normal 280-300)mOsm/L (Normal 280-300)
FiltrationFiltration
OsmosisOsmosis
–Movement of fluid through semipermeable membrane Movement of fluid through semipermeable membrane
–Concentration controls- solvent moves to make concentrations even although volume is not
Filtration Pressures in a CapillaryFiltration Pressures in a Capillary
Problem Examples:
Edema
Congestive heart failure
DiffusionDiffusion - movement of solutes against a concentration
gradient; tries to to balance cations to balance cations ++ with anions with anions --
Active TransportActive Transport
• Requires energy from metabolism to move larger or uneven substances across cell membranes
– Glucose needs insulin to enter cell– Na/K pump
Active Transportation Active Transportation of Glucoseof Glucose
Na-K Pump:Na-K Pump: For every molecule of ATP, 3 molecules of Na For every molecule of ATP, 3 molecules of Na move to outside of cell and 3 molecules of K move inside the cellmove to outside of cell and 3 molecules of K move inside the cell
Osmolality and TonicityOsmolality 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 TonicityOsmosis and TonicityNa is the main determinant of plasma tonicityNa is the main determinant of plasma tonicity. .
Thirst and ADH release
Swelling of cells
Problem Examples:
Edema
Congestive heart failure
HYPOHYPOHYPOHYPO
TonicityTonicity0.45% saline (1/2 normal)
Moves fluid into cells
ISOISOISOISO
TonicityTonicitySame osmolarity as plasma
0.9 % saline (Normal saline)
– no fluid shift
HYPERHYPERHYPERHYPER
TonicityTonicity
3% saline
Pulls fluid from cells
TonicityTonicity
ElectrolytesElectrolytes+
-
-
-
--
+
+
++
ECF ElectrolytesECF ElectrolytesECF ElectrolytesECF Electrolytes
Sodium - Na Sodium - Na 135-145mEq/L135-145mEq/L
Potassium - K Potassium - K 3.5-5.0 mEq.L3.5-5.0 mEq.L
Calcium - Ca Calcium - Ca 4.5-5.5 mEq/L 4.5-5.5 mEq/L
Magnesium - MgMagnesium - Mg 1.5 - 2.5 mEq/L1.5 - 2.5 mEq/L
Chloride - Cl Chloride - Cl 90-110 mEq/L90-110 mEq/L
Bicarbonate – HCOBicarbonate – HCO33
• ArterialArterial 22-26 mEq/L 22-26 mEq/L
• VenousVenous 24-30 mEq/L 24-30 mEq/L
Sodium and ECFVSodium and ECFV
• The total amount of Sodium in ECF is the The total amount of Sodium in ECF is the major major determinantdeterminant of the size of the ECF Volume 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
Sodium RegulationSodium Regulation1) Kidney receptors sense changes in renal perfusion causing
renin-angiotensin system to retain sodium in kidney.
2) Volume receptors in great veins sense filling and release atrial natriuretic factor that promotes Na excretion.
3) Pressure receptors in aorta and carotid sinus activate sympathetic NS to retain Na.
Water ALWAYS follows NaWater 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 RegulationWater Regulation(Hypo- and Hyper-Natremia are always a Hypo- and Hyper-Natremia are always a
problem with water, problem with water, notnot Sodium) Sodium)
I. Osmolality increase in ECF -> Thirst
II. Renal responsiveness to tonicity
III. Adequate delivery of water and solutes to glomerulus of kidney (Problem: Early reabsorption of water due to volume depletion or edematous states)
IV. Water conservation mechanisms in kidney (Can be overridden by diuretics either in loop or in distal tubule.
V. ADH in response to tonicity changes, i.e., Na, or in response to volume changes (Problems: SIADH and DI)
DiureticsDiuretics
• 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 Manifestations of Fluid, and Electrolyte ImbalancesElectrolyte Imbalances
• Imbalances of Intake and Output and Body Weight
• Changes in Mental Status• Changes in Vital Signs • Abnormal Tissue Hydration• Abnormal Muscle Tone
Nursing InterventionsNursing InterventionsNursing InterventionsNursing Interventions
• Health Promotion– Teaching depending upon setting
• Altered Function– Oral fluid increase– Oral fluid restriction– Electrolyte replacement
• Diet or supplement• IV therapy
Serum Electrolytes
Name SymbolNormal Value
Function Hypo Causes Hyper Causes
Sodium Na 135-145Maintains
concentration of ECF
GI LossesDiuretics, burns, wound
drainage
High fever, heatstroke due to insensible water loss, diabetes insipidus
Potassium K 3.5-5.0
Major ICF cation; cellular and
metabolic functions including cardiac
rhythms
GI Losses – diarrhea, vomiting, duretics,
diaphoresis
AcidosisRenal disease
K containing drugsK salt substitute
Calcium Ca 4.5-5.5
Transmission of nerve impulses,
cardiac contractions, bone,
blood clotting
Chronic renal failure, Vit D deficiency,
pancreatiti,s, loop diuretics, diarrhea
hyporparathyroidism
Mult. Myeloma, thiazide diuretics,
malignancies,
Magnesium Mg 1.5-2.5Muscle, RBC’s and CNS, metabolism
Diarrhea, vomiting, NG Suction, hyper aldosteronism
Maalox and Milk of Magnesia in patients
with renal failure
Phosphate Phos 1.7-4.6Muscle, RBC’s,
CNs, w/ Calcium in bones and teeth
Malnourished, alcohol withdrawal, phosphate-
binding antacids
Renal failure, chemoTx, enemas
containing
Objective DataObjective Data
• Neck Vein DistentionNeck Vein Distention• Central Venous PressureCentral Venous Pressure• Pulmonary Artery PressurePulmonary Artery Pressure• Bowel AssessmentBowel Assessment• Laboratory and Diagnostic TestsLaboratory and Diagnostic Tests
– Urine TestsUrine Tests– Blood TestsBlood Tests
Central Venous Pressure or Central Venous Pressure or Jugular Venous DistentionJugular Venous Distention
AssessmentAssessment
• Subjective Data– Normal Pattern Identification– Risk Identification– Dysfunction Identification
• Objective Data—Physical Assessment– Intake and Output– Body Weight– Integumentary Assessment
Solution Osmolality Usage and Limitations
NS - 0.9% NaCl Isotonic (308mOsm/L)
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
1/2 NS - 0.45%NaCl Hypotonic (154 mOsm/L)
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.
D5 1/2 NS - 5% Dextrose & 0.45NaCl
Hypertonic (406 mOsm/L)
to promote renal function and excretion; basically the same as .45NS except provides 170 calories per liter
D5NS - 5% Dextrose & 0.9NaCl
Hypertonic (559 mOsm/L)
to treat fluid volume deficit; for daily maintenance of body fluids and nutrition; basically the same as NS, except provides 170 calories per liter
D5W - 5% Dextrose in water Isotonic (252 mOsm/L)
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
Lactated Ringer’s Solution Isotonic (273 mOsm/L)
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.
10% Dextran 40 in 0.9%NS Isotonic (308 mOsm/L)
plasma expander
Third Spacing: Third Spacing: Loss of fluid into a space that cannot contribute Loss of fluid into a space that cannot contribute
to ICF/ECF equilibriumto ICF/ECF equilibriumS&S:S&S: Urine output decreasesUrine output decreases
Increased heart rateIncreased heart rate
Decreased BPDecreased BP
Decreased CVPDecreased CVP
Increased body weightIncreased body weight
EdemaEdema
I & O imbalanceI & O imbalance
Causes:Causes: Burns Burns
Ascites Ascites
Peritonitis Peritonitis
Bowel obstruction Bowel obstruction
Massive bleedingMassive bleeding into joint or body cavityinto joint or body cavity
Acid Base BalanceAcid Base Balance
Two systems work to maintain correct pH.Two systems work to maintain correct pH.
Respiratory System by adjusting respirations.
Metabolic system by adjusting serum HCO3
Acid Base BalanceAcid Base Balance
AcidosisAcidosispH < 7.4pH < 7.4
Increased paCO2
Decreased HCO3
Acid…………………BaseAcid…………………Base
• High C02• Low HCO3
• Low CO2• High HCO3
pCO2 = 35-45
HCO3 = 22-28
pCO2 = 35-45
HCO3 = 22-28
Respiratory AcidosisRespiratory Acidosis
• Hypoventilation for any reason• COPD• Paralysis of respiratory muscles• Cardiac Arrest – Code
Metabolic AcidosisMetabolic Acidosis
• Starvation• DKA• Renal Failure• Lactic Acidosis from heavy exercise• Drugs – EtOH, ASA• Diarrhea
AlkalosisAlkalosispH > 7.4pH > 7.4
Decreased CO2
Increased HC03
Respiratory Alkalosis
– Hyperventilation from any cause
– Pneumonia
– Too high ventilator settings
Metabolic AlkalosisMetabolic Alkalosis
• Excessive vomiting• Gastric suctioning• Hypokalemia OR Hypercalcemia• Excess aldosterone• Drugs – Steroids, diuretics, NaHCO3
Easy Read of Blood GasesEasy Read of Blood Gases
1. Check pH
2. <7.4 = Acidosis; > 7.4 = alkalosis
3. 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.