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.