fluid and electrolyte concept

7/29/2019 Fluid and Electrolyte Concept

1/40

LESTARI SUKMARINI, MNSKMB 2008

FLUID and ELECTROLYTE

CONCEPT


2/40

Objectives:

A. Review mechanism of fluid and electrolytebalance.1. body water distribution2. body electrolyte component3. mechanism for fluid and

electrolyte movement4. regulation of fluid and electrolyte balance

B. Fluid and electrolyte imbalances

1. fluid imbalancea. fluid deficitb. fluid excess

2. electrolyte imbalancea. electrolyte deficit

K+, Na+, Ca, Mgb. electolyte excess

K+, Na+, Ca, Mg


3/40

Body Fluid distribution

Body fluids constitute 55-

60% of body weight

Higher in males due togreater muscle mass andlower fat

Total body water declinesthroughout life with changesin muscle mass and fat

Water occupies 2 main fluidcompartments:

Intracellular (~2/3of total water)Extracellular (~1/3total water)

plasma (20%)interstitial fluid

(80%)


4/40

Hydrostatic pressure Oncotic pressure

Plasma


5/40

Fluid exchange


6/40

Fluid dynamics at the capillary

CHP = Capillary Hydrostatic Pressure COP = Capillary Osmotic PressureIFHP = Interstitial Fluid Hydrostatic Pressure IFOP + Interstitial Fluid Osmotic

Pressure


7/40

Electrolytes: the mineral salts that

conduct the electrical energy of

the body, perform a cellular

balancing act by allowing nutrients

into the cell, while helping to

remove waste products.


8/40

Water balance Normally body fluid volume

remains constant water loss = water gain

Water gain:

~60% ingested liquids

~30% ingested in foods

~10% metabolic water (fromoxidation)

Water loss:

~4% faeces

~28% insensible water loss(skin & lungs)

~8% sweat

~60% urine

Additional fluid loss inmenstrual flow in females of

reproductive age


9/40

Normal fluid and electrolyte requirements

Daily water requirements Weight (kg) x 25-35 mL = mL fluid required daily 25 mL/kg for CHF or renal disease 30 mL/kg for average adults 35 mL/kg for patients with infection or drainingwounds

Daily electrolyte requirements Sodium 2 - 3 mEq/100ml H2O /day

Potassium 1 - 2 mEq/100ml H2O /day

Chloride 2 - 3 mEq/100ml H2O /day


10/40

Electrolytes This provides information about serum Na+, K+, Cl-, HCO3-

BUN and Cr These measures provide an indication of renal perfusion. An elevatedBUN generally reflects intravascular depletion. Creatinine is a usefulindicator of acute renal failure.

CBC The CBC may provide some indication of hemoconcentration in cases ofdehydration. The WBCs and differential cell count are useful indicatorsof infection. Platelets can elevate as acute phase reactants.

Urine

AnalysisThe specific gravity of the urine is related to the patient's hydrationstate. In cases of renal disease, it can help classify the condition. Urine

ions can be specifically requested, and are helpful in determining

whether sodium is being retained or not.

Examinations to identify fluid/electrolyte problems


11/40

Serum/UrineOsmolarity

A true measure of serum osmolarity can be compared to the calculated

osmolarity. Normally, true osmolarity is about 10 mEq/L higher than calculated

due to the presence of particles which are not in the basic osmolarity equation.

If there is a greater "osmolar gap" than this, the presence of additional particlesshould be considered (such as alcohol or mannitol). The osmolarity of serum

determines whether a patient is in an isotonic state or if this state has been

disturbed. Urine osmolarity is helpful in determining if the kidney is doing its

job of concentrating urine.Total Protein Total protein, and sometimes albumin levels, are indirect measures of both liver

function (where they are produced), dietary protein intake, and renal loss. If

serum protein levels fall, the intravascular oncotic pressure falls and fluid

migrates to "third spaces". This can be seen in liver disease, nephrotic

syndromes, malnutrition and other cases.Arterial Blood

Gas In addition to providing information about the patient's blood gases andassisting in classification of acidosis or alkylosis, the ABG yields informationabout bicarbonate levels. Usually, STAT electrolytes can also be obtained from

a blood gas sample, with turn around time better than serum chemistry.


12/40

Water homeostasis and serum osmolality

Major factors Normal cellular function requires normalserum osmolality. Water homeostasis maintains serumosmolality.contributing to serum osmolality are Na, glucose and

BUN.

Serum osmolality estimation:(2 x plasma Na) + (plasma glucose/18) + (BUN/2.8)

Normal serum osmolarity = 280-300 mOsm


13/40

Type of intravenous fluid for replacementtherapy:

Isotonicsame osmotic pressure as bodyfluids (240-349 mOsm)

Hypotoniclower osmotic pressure thanbody fluids (less than 240 mOsm)

Hypertonichigher osmotic pressure than

body fluids (greater than 340)


14/40

Fluid Imbalances

Fluid excess: CHF

Kidney failure

Fluid deficit: Diarrhea

Blood loss


15/40

Responses to imbalances ?


16/40

Regulation of body water loss (dehydration)

Aldosterone

Na+&Waterreabsorbtion inrenal tubules

ReleaseADH

Water retention


17/40

Electrolyte Imbalances


18/40


19/40

Hyponatremia: serum Na < 130mEq/L

Sodium deficit calculation: [(normalNa(mEq/L)) (measured Na(mEq/L)]x TBW (L)


20/40


21/40


22/40

Fluid electrolyte management

Estimating the fluid problem1) Check the weightRapid changes in weight likely represent changes in TBW.

(2) History

Ask about losses (diarrhea, vomiting, how much, howoften), attempts at replacement (what fluids used, howmuch given, how successful), urine output.

(3) Physical exam findingsMental status, pulse, BP, body weight, mucous

membranes, skin turgor, skin color.

(4) Laboratory evaluationSerum chemistries, hematocrit, and urine studies can

guide therapy and check forcomplications.


23/40

Oral therapy

Oral rehydration with electrolyte solutions is safe,efficacious and convenient. Can be used as first linetherapy in nearly all fluid and electrolyte aberrationsexcept severe circulatory compromise.


24/40

IV therapy reestablish effective circulating volume

a) What IV fluid should be used?Initial IV therapy should be with isotonic fluid to improveeffective circulating volume.


25/40

b) How much IV fluid should I give initially?

Use clinical findings to determine if patient isresponding (mental status, vital signs, urine output).Repeat this infusion if necessary.

c) How should continue IV fluids?do not require continued IV fluids after effectivecirculation has been restored.

Continue IV fluids in situations where oralrehydration will be difficult, such as high ongoinglosses, severe electrolyte abnormalities,poor mental status or inability to tolerate enteral fluids.


26/40

Continuing IV therapy considers:

(a) Estimate remaining deficitsVolume: Check current weight and compare to desired baseline. If usingpreresuscitationweight, consider the amount of volume given inresuscitation.(b) Estimate daily needs

Estimate daily needs for water and electrolytes, as for any patient. Adjustbased on the clinical situation (e.g., fever, coma, ventilator, etc.)(c) Consider ongoing lossesMonitor for losses such as stool, drains, etc. Consider replacing these asneeded.(d) Provide therapy

Add up water and electrolyte needs from deficits and daily requirements.


27/40

Hypernatremia: serum Na > 150 mEq/L

Significant neurological effects usually seenwith Na > 160 mEq/L

Free water deficit calculation:

measured Na (mEq/L)

desired Na (mEq/L) X TBW (L)} - TBW (L)

Use 145mEq/L as desired Na; estimate TBW as0.6L/kg x body weight (kg)


28/40


29/40


30/40


31/40


32/40


33/40


34/40


35/40


36/40

References:

Bennet, G.2001.Cecl Textbook of medicine 21st ed. Philadelphia: WBSaunders.

Kobriger AM. Hydration: Maintenance: Dehydration, LaboratoryValues, and Clinical Alterations. Chilton, WI: Kobriger Presents, Inc;2005.

Mahan LK, Escott-Stump, S. Krauses Food and Nutrition Therapy.12th ed.

St. Louis, MO: WB Saunders; 2008. National Academy of Science, Institute of Medicine, Food and

Nutrition Board.Dietary reference intakes for water, potassium,sodium, chloride, and sulfate (2004). Available at:http://fnic.nal.usda.gov/nal_display/index.php?infocenter=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141

&level4_id=10592. Accessed February 25, 2008. http://www.rd411.com/article.php?ID=9
http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592http://fnic.nal.usda.gov/nal_display/index.php?info_center=4&tax_level=4&tax_subject=256&topic_id=1342&level3_id=5141&level4_id=10592


37/40

Regulation of the acid-base balance(pH regulation)

Definition: pH = unit of measure for the concentration of

hydrogen ions in aqueous solutions; theseions determine the acid/base content of the

solution. " Acidic solutions : pH < 7.0 (and down to

not more than 0) and have an excess ofhydrogen ions.

" Basic solutions : pH > 7.0 (to a maximumof 14). These solutions are capable ofabsorbing hydrogen ions.


38/40

Regulation of the acid-base balance


39/40

Kidney & lung excreting an excess acid orbase.

Buffer system: HCO3, protein, phospate,

haemoglobin, etc.

Haemostasis == H+excretion & buffering


40/40

Thank you ..

fluid and electrolyte concept

Documents