chapter 29 fluids and electrolytes copyright © 2014 by mosby, an imprint of elsevier inc

Chapter 29

Fluids and Electrolytes

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Total body water Composed of:

• Intracellular fluid (ICF)

• Interstitial fluid (ISF)

• Plasma volume (PV)

60% of adult human body is water

Fluid Balance

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 2

Intravascular fluid (IVF) Fluid inside blood vessels

Extravascular fluid (EVF) Fluid outside blood vessels

• Lymph, cerebrospinal fluid

Fluid Balance (cont’d)


Extravascular volume Plasma Interstitial fluid (ISF): fluid in space between cells,

tissues, and organs Extracellular volume

ISF (interstitial fluid) ICF (intracellular fluid)



Distribution of Total Body Water


Plasma proteins exert constant osmotic pressure Colloid oncotic pressure (COP) Normally 24 mm Hg

ISF exerts hydrostatic pressure (HP) Normally 17 mm Hg



Colloid Osmotic Pressure


Edema Dehydration and fluid loss Acid-base balance



Solutions containing fluids and electrolytes that are normally found in the body

Do not contain proteins (colloids) No risk for viral transmission, anaphylaxis, or

alteration in coagulation profile

Crystalloids


Better for treating dehydration rather than expanding plasma volume

Used as maintenance fluids to: Compensate for insensible fluid losses Replace fluids Manage specific fluid and electrolyte disturbances Promote urinary flow

Crystalloids (cont’d)


Normal saline (0.9% sodium chloride) Half normal saline (0.45% sodium chloride) Hypertonic saline (3% sodium chloride) Lactated Ringer’s D5W



Indications include: Acute liver failure Acute nephrosis Adult respiratory distress syndrome Burns Cardiopulmonary bypass Hypoproteinemia Renal dialysis Reduction of the risk for DVT Shock



Adverse effects May cause edema, especially peripheral or pulmonary May dilute plasma proteins, reducing COP Effects may be short-lived Prolonged infusions may worsen alkalosis or acidosis



Protein substances Increase COP Move fluid from interstitial compartment to

plasma compartment (when plasma protein levels are low) Albumin 5% and 25% (from human donors) Dextran 40, 70, or 75 (a glucose solution) Hetastarch (synthetic, derived from cornstarch)

Colloids


Adverse effects Usually safe May cause altered coagulation, resulting in bleeding Have no clotting factors or oxygen-carrying capacity Rarely, dextran therapy causes anaphylaxis or renal

failure

Colloids (cont’d)


Only class of fluids that are able to carry oxygen Increase tissue oxygenation Increase plasma volume Most expensive and least available fluid

because they require human donors

Blood Products


Increase COP and PV Pull fluid from extravascular space into intravascular

space (plasma expanders) RBC products also carry oxygen Increase body’s supply of various products (such as

clotting factors, hemoglobin)

Blood Products (cont’d)


Indications Cryoprecipitate and plasma protein factors (PPF)

• Management of acute bleeding (greater than 50% slow blood loss or 20% acutely)

Fresh frozen plasma (FFP)• Increase clotting factor levels in patients with demonstrated

deficiency



Indications (cont’d) Packed red blood cells (PRBCs)

• To increase oxygen-carrying capacity in patients with anemia, in patients with substantial hemoglobin deficits, and in patients who have lost up to 25% of their total blood volume

Whole blood• Same as for PRBCs, except that whole blood is more

beneficial in cases of extreme (greater than 25%) loss of blood volume because whole blood also contains plasma

• Contains plasma proteins, which help draw fluid back into blood vessels from surrounding tissues

Blood Products


Classroom Response Question

A patient is taken to the trauma unit after a motorcycle accident. It is estimated that he has lost 30% of his blood volume and he is in hypovolemic shock. The nurse anticipates a transfusion with which blood product?

A.Packed red blood cells

B.Whole blood

C.Cryoprecipitate

D.Fresh frozen plasma


Adverse effects Incompatibility with recipient’s immune system Crossmatch testing Transfusion reaction Anaphylaxis Transmission of pathogens to recipient (hepatitis,

HIV)



Principal ECF electrolytes Sodium cations (Na+) Chloride anions (Cl−)

Principal ICF electrolyte Potassium (K+)

Others Calcium, magnesium, phosphorus

Electrolytes


Most abundant positively charged electrolyte inside cells

95% of body’s potassium is intracellular Potassium content outside of cells ranges from

3.5 to 5 mEq/L Potassium levels are critical to normal body

function

Potassium


Potassium obtained from foods Fruit and fruit juices (bananas, oranges, apricots,

dates, raisins, broccoli, green beans, potatoes, tomatoes), meats, fish, wheat bread, and legumes

Excess dietary potassium excreted via kidneys Impaired kidney function leads to higher serum levels,

possibly toxicity

Potassium (cont’d)


Hyperkalemia: excessive serum potassium;serum potassium level over 5.5 mEq/LPotassium supplementsACE inhibitorsRenal failureExcessive loss from cellsPotassium-sparing diuretics


Burns Trauma Metabolic acidosis Infections


Hypokalemia: deficiency of potassium; serum potassium level less than 3.5 mEq/L

Excessive potassium loss (rather than poor dietary intake)


Burns Thiazide, thiazide-like,

and loop diuretics Vomiting Malabsorption Others

Alkalosis Corticosteroids Diarrhea Ketoacidosis Laxative misuse Hyperaldosteronism Increased secretion

of mineralocorticoids


Hypokalemia, in the presence of digoxin therapy, can cause digoxin toxicity, resulting in serious ventricular dysrhythmias



Potassium is responsible for: Muscle contraction Transmission of nerve impulses Regulation of heartbeat Maintenance of acid-base balance Isotonicity




Which condition does the nurse identify as a late manifestation of hypokalemia?

A.Muscle weakness

B.Hypotension

C.Palpitations

D.Lethargy


Main indication Treatment or prevention of potassium depletion when

dietary means are inadequate Other therapeutic uses

Stop irregular heartbeats Management of tachydysrhythmias that can occur

after cardiac surgery



Adverse effects Oral preparations

• Diarrhea, nausea, vomiting, GI bleeding, ulceration

IV administration• Pain at injection site

• Phlebitis

Excessive administration• Hyperkalemia

• Toxic effects



Hyperkalemia manifestations Muscle weakness, paresthesia, paralysis, cardiac

rhythm irregularities (leading to possible ventricular fibrillation and cardiac arrest)

Treatment of severe hyperkalemia IV sodium bicarbonate, calcium gluconate or calcium

chloride, dextrose with insulin Sodium polystyrene sulfonate (Kayexalate) or

hemodialysis to remove excess potassium




A patient is hypokalemic and will be receiving intravenous potassium. The patient is not on a heart monitor. How should the nurse administer the potassium replacement?

A.IV push

B.No more than 10 mEq/hr

C.No more than 20 mEq/hr

D.40 mEq/hr


Most abundant positively charged electrolyte outside cells

Normal concentration outside cells is 135 to 145 mEq/L

Maintained through dietary intake of sodium chloride Salt, fish, meats, foods flavored or preserved with salt

Sodium


Hyponatremia: sodium loss or deficiency; serum levels below 135 mEq/L Symptoms

• Lethargy, stomach cramps, hypotension, vomiting, diarrhea, seizures

Causes• Same causes as hypokalemia; also excessive perspiration

(during hot weather or physical work), prolonged diarrhea or vomiting, or renal disorders

Sodium (cont’d)


Hypernatremia: sodium excess; serum levels over 145 mEq/L Symptoms

• Water retention (edema), hypertension

• Red, flushed skin; dry, sticky mucous membranes; increased thirst; elevated temperature; decreased urine output

Causes• Poor renal excretion stemming from kidney malfunction;

inadequate water consumption and dehydration

Sodium (cont’d)


Sodium is responsible for: Control of water distribution Fluid and electrolyte balance Osmotic pressure of body fluids Participation in acid-base balance

Sodium (cont’d)


Main indication Treatment or prevention of sodium depletion when

dietary measures are inadequate Mild

• Treated with oral sodium chloride and/or fluid restriction

Severe• Treated with intravenous normal saline or lactated Ringer’s

solution

Sodium (cont’d)


Adverse effects Oral administration

• Nausea, vomiting, cramps

IV administration• Venous phlebitis

Sodium (cont’d)


Assess baseline fluid volume and electrolyte status

Assess baseline vital signs Assess skin, mucous membranes, daily weights,

I&O Before giving potassium, assess ECG Assess for contraindications to therapy Assess transfusion history Establish venous access as needed

Nursing Implications


Monitor serum electrolyte levels during therapy Monitor infusion rate, appearance of fluid or

solution, infusion site Observe for infiltration, other complications of IV

therapy

Nursing Implications (cont’d)


Parenteral infusions of potassium must be monitored closely IV potassium must not be given at a rate faster than

10 mEq/hr to patients who are not on cardiac monitors. For critically ill patients on cardiac monitors, rates of 20 mEq/hr or more may be used.

NEVER give as an IV bolus or undiluted



Oral forms of potassium Must be diluted in water or fruit juice to minimize GI

distress or irritation Monitor for complaints of nausea, vomiting, GI pain,

or GI bleeding




A patient with a serum potassium of 6.0 mEq/L is ordered polystyrene sulfonate (Kayexalate) via the NG. When administering the medication the nurse should

A.administer the drug with sorbitol.

B.administer the drug with water.

C.administer the drug with an antacid.

D.administer the drug with a laxative.


Administer colloids slowly Monitor for fluid overload and possible heart

failure For blood products, follow administration

procedures closely Monitor closely for signs of transfusion reactions




Which solution should the nurse administer with packed red blood cells?

A.Lactated Ringer’s

B.0.9% sodium chloride

C.D5W

D.0.45% sodium chloride


Monitor for therapeutic response Normal lab values

• RBCs, WBC, H&H, electrolyte levels

Improved fluid volume status Increased tolerance to activities

Monitor for adverse effects



chapter 29 fluids and electrolytes copyright © 2014 by mosby, an imprint of elsevier inc

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