Fluid & Electrolytes

Nur 102 Spring 2015Belinda Lowry, MSN, RN, CCRN

1Body FluidAdult body is 60% water;Older adult 45-55% water40% is intracellular fluid20% extracellular fluid15% interstitial (tissue) fluid5% intravascular fluid

Water makes up a substantial proportion of body weight. In fact, about 60% of the body weight of an adult man is water. This proportion decreases with age; approximately 50% of an older man's weight is water. Women typically have less water content than men. Obese people have less water in their bodies than lean people because fat contains less water than muscle. The term fluidmeans water that contains dissolved or suspended substances such as glucose, mineral salts, and proteins.

Body fluids are located in two distinct compartments:extracellular fluid (ECF)outside the cells, andintracellular fluid (ICF)inside the cells. In adults ICF is approximately two thirds of total body water. ECF is approximately one third of total body water. ECF has two major divisions(intravascular fluidandinterstitial fluid) and a minor division(transcellular fluids). Intravascular fluid is the liquid portion of the blood (i.e., the plasma). Interstitial fluid is located between the cells and outside the blood vessels. Transcellular fluids such as cerebrospinal, pleural, peritoneal, and synovial fluids are secreted by epithelial cells.3Body FluidsOsmolality (aka osmolarity)The osmotic pull exerted by all particles (solutes) per unit of waterMainly controlled by sodium

TonicityThe effect of fluid on cellular volumeFluid that contains a large number of dissolved particles is more concentrated than the same amount of fluid that contains only a few particles.Osmolalityof a fluid is a measure of the number of particles per kilogram of water. Some particles (e.g., urea) pass easily through cell membranes; others such as Na+cannot cross easily. The particles that cannot cross cell membranes easily (nonpermeant particles) determine tonicity of a fluid (Caon, 2008).

Osmolarityis the number of milliosmoles/liter (mOsm/L) of solution: concentration of the solution. (calculated)

Osmolalityis the number of milliosmoles/ kg (mOsm/kg ) of solvent: concentration of the particles dissolved in the solution (measured with an osmometer)4TonicityIV fluids have different tonicities, giving different results on body fluid maintenanceIsotonic 0.9% sodium chloride (normal saline), D5W, LRHypotonic0.45% sodium chloride (1/2 NS)HypertonicD5 NS, D5LR, D10W

A fluid with the same concentration of nonpermeant particles as normal blood is calledisotonic. Ahypotonicsolution is more dilute than the blood, and ahypertonicsolution is more concentrated than normal blood.

Hypotonicsolutions will move water into the cell, causing the cell to swell and potential burst. By lowering the serum osmolarity, the body fluids shift out of the blood vessels into the interstitial tissue and cells. Hypotonic solutions hydrate the cells and can deplete the circulatory system.

Hypertonicsolutions conversely cause the water from within a cell to move to the ECF compartment, causing the cell to shrink. These solutions are used to replace electrolytes. Hypertonic dextrose solutions when used alone, shifts ECF from interstitial to plasma.

5Movement of Water & Electrolytes

Osmosis: fluid moving from the lower concentration to the higher concentration; it wants to cause dilution

6

https://www.youtube.com/watch?v=SSS3EtKAzYc8IV Fluids: Four classificationsCrystalloids: replacement and maintenance of fluidsNS, NS, D5s, LR, etc.Colloids: volume expandersHetastarch (hespan), dextranBlood and blood productsWhole blood, PRBC, platelets, plasma, albuminLipids: fat emulsion solutionTPN (total parenteral nutrition) IV foodFluid BalanceIntake: Anything going inOral fluids, IV fluids, irrigationsOutput: Anything coming outUrine, liquid stool, emesis, NGT output, drainsIntake Output = Balance1200 ml intake 3000 ml output = - 1800 balanceIs patient overloaded or dry?Insensible loss: sweat, weeping, lungs, formed stoolFluid homeostasis is the dynamic interplay of three processes: fluid intake and absorption, fluid distribution, and fluid output (Felver, 2010b). Human total daily fluid output consists of hypotonic sodium-containing fluid. People must have intake of an equivalent amount of hypotonic sodium-containing fluid (or water plus foods with some salt) to maintain fluid balance.10Fluid ImbalanceVolume imbalanceDisturbances in the amount of fluid in the extracellular compartment

Osmolality imbalanceDisturbances of the concentration of body fluidsMostly affects sodiumIf disease processes, medications, or other factors disrupt fluid intake or output, imbalances sometimes occur (Felver, 2010b). For example, with diarrhea there is an increase in fluid output, and a fluid imbalance (dehydration) occurs if fluid intake does not increase appropriately. There are two major types of fluid imbalances: volume imbalances and osmolality imbalances (Fig. 41-7). Volume imbalances are disturbances of theamount of fluid in the extracellular compartment. Osmolality imbalances are disturbances of theconcentration of body fluids. Volume and osmolality imbalances occur separately or in combination.

ECV excessoccurs when there is too much isotonic fluid in the extracellular compartment. Intake of sodium-containing isotonic fluid has exceeded fluid output. For example, when you eat more salty foods than usual and drink water, you may notice that your ankles swell or rings on your fingers feel tight and you gain 2lbs (1kg) or more overnight. These are manifestations of mild ECV excess.

11Fluid Overload & Deficit Causes

Overload: Excessive fluid replacement, kidney failure, heart failure, water intoxication

Deficit: Hemorrhage, vomiting, diarrhea, ileostomies, burns, profuse sweating, severe wounds, long-term NPO, diuretics, GI suctions, impaired thirst or PO intake, fever, unconsciousness

12Fluid OverloadShortness of breathAdventitious breath soundsSwelling, edemaNeck vein distentionWeight gain1 liter water = 1 kg1 kg = 2.2 lbsSometimes ALOC

Fluid Deficit s/sxLow BPIncreased HRDecreased urine output (UO)Decreased skin turgorDry mucous membranesSometimes ALOC

Causes of Fluid Imbalance*** TABLE 41-3 *** (p. 888)Volume deficitDecreased salt and water intake, increased GI output, bleeding, diureticsVolume excessIncreased salt and water intake, excess isotonic IV fluid, decreased renal output/function

I/O Practice: shift 0700-1500Oral intake: 600 mlIV fluids: 1000 mlUrine: 850 mlEmesis: 200 ml

What is the total I/O for the shift?What is patients balance for the shift?I/O Practice: shift 1500-2300Oral intake: 300 mlIV fluids: 850 mlIV medication: 50 mlBlood: 350 mlUrine: 400 mlIleostomy: 300 ml

What is the total I/O for the shift?What is the patients balance for the shift?

I/O Practice: shift 2300-0700Oral intake: 500 mlIV fluids: 750 mlIrrigation: 100 ml (down nasogastric tube)Urine: 530 mlAmount in NGT suction canister: 200 ml (canister was marked at 50 ml @ beginning of shift)Wound drain: 30 ml

What is the total I/O for the shift?What is the patients balance for the shift?BONUSWhat was the total I/O for the 24-hours?What was the patients balance for the day?https://www.youtube.com/watch?v=t1nwSuWr_q820Break!

21https://www.youtube.com/watch?v=-Vw2CrY9Igs22ElectrolytesSubstances in the body that carry electrical chargesNecessary to transmit nerve impulses to muscles, and to contract skeletal and smooth musclesPositive-charged most plentiful (cations)Potassium, magnesium, sodium, calcium

Fluid in the body compartments contains mineral salts known technically aselectrolytes. An electrolyte is a compound that separates intoions(charged particles) when it dissolves in water. Ions that are positively charged are calledcations; ions that are negatively charged are calledanions. Cations in body fluids are sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium ions (Mg2+). Anions in body fluids are chloride (Cl) and bicarbonate (HCO3-). Anions and cations combine to make salts.

Factors such as diarrhea, endocrine disorders, and medications that disrupt electrolyte homeostasis cause electrolyte imbalances. Electrolyte intake greater than electrolyte output or a shift of electrolytes from cells or bone into the ECF causes plasma electrolyte excess. Electrolyte intake less than electrolyte output or shift of electrolyte from the ECF into cells or bone causes plasma electrolyte deficit.

23Sodium (Na+)Normal value 135-145 mEq/LMajor electrolyte that regulates body fluidsPromotes transmission and conduction of nerve impulsesConstantly shifts into cells while K+ shifts out of cells to maintain water balance and neuromuscular activity

SodiumHyponatremiaHypernatremiaNa < 135 mEq/LResults from vomiting, diarrhea, surgery, potent diureticss/sx include:Weakness, headaches, lethargy, confusion, seizures, dry mucous membranesTreatment: slow correction with NS3% NS may be used for 145 mEq/LResults from dehydration and use of some antibiotics and cortisone medicationss/sx include:Agitation, flushed & dry skin, tachycardia, muscle twitching, hyperreflexiaTreatment: sodium restriction, hypotonic solutions, free water flushes

In an osmolality imbalance body fluids become hypertonic or hypotonic, which causes osmotic shifts of water across cell membranes. The osmolality imbalances are calledhypernatremiaandhyponatremia.

Hypernatremia, also calledwater deficit, is a hypertonic condition. Two general causes make body fluids too concentrated: loss of relatively more water than salt or gain of relatively more salt than water (Felver, 2010b).Table 41-3lists specific causes under these categories. When the interstitial fluid becomes hypertonic, water leaves cells by osmosis, and they shrivel. Signs and symptoms of hypernatremia are those of cerebral dysfunction, which arise when brain cells shrivel. Hypernatremia may occur in combination with ECV deficit; this combined disorder is called clinicaldehydration.

Hyponatremia, also calledwater excess orwater intoxication, is a hypotonic condition. It arises from gain of relatively more water than salt or loss of relatively more salt than water (Felver, 2010b) (seeTable 41-3). The excessively dilute condition of interstitial fluid causes water to enter cells by osmosis, causing the cells to swell. Signs and symptoms of cerebral dysfunction occur when brain cells swell.

25Potassium (K+)Normal value 3.5-5.3 mEq/LNecessary for transmission and conduction of nerve impulses and for contraction of skeletal, cardiac, and smooth musclesAlso necessary for enzyme action for glycolysis and protein formation

PotassiumHypokalemiaHyperkalemiaK+ < 3.5 mEq/LResults from cell leakage secondary to trauma, injury, surgery, shockCan also result from vomiting and diarrheaSide effect of diuretic and laxative therapiess/sx include:n/v, confusion, dysrhythmias, soft/flabby musclesTreatment: PO or IV replacement (SLOW infusion over 2 hours minimum)

K+ > 5.3 mEq/LResults from renal insufficiency or large doses of potassium over times/sx include:Nausea, abdominal cramps, tachycardia, weakness, tingling in extremities, tall peaked T-waves on ECG rhythmTreatment: kay-exalate, calcium gluconate, IV insulin + D50 amp

Hypokalemiais abnormally low potassium concentration in the blood. Hypokalemia results from decreased potassium intake and absorption, a shift of potassium from the ECF into cells, and an increased potassium output (Table 41-5). Common causes of hypokalemia from increased potassium output include diarrhea, repeated vomiting, and use of potassium-wasting diuretics. People who have these conditions need to increase their potassium intake to reduce their risk of hypokalemia. Hypokalemia causes muscle weakness, which becomes life threatening if it includes respiratory muscles and potentially life-threatening cardiac dysrhythmias.

Hyperkalemiais abnormally high potassium ion concentration in the blood. Its general causes are increased potassium intake and absorption, shift of potassium from cells into the ECF, and decreased potassium output (seeTable 41-5). People who have oliguria (decreased urine output) are at high risk of hyperkalemia from the resultant decreased potassium output unless their potassium intake also decreases substantially. Understanding this principle helps you remember to check urine output before you administer IV solutions containing potassium. Hyperkalemia can cause muscle weakness, potentially life-threatening cardiac dysrhythmias, and cardiac arrest.

27Calcium (Ca)Normal value: 8.5-10.5 mg/dLPromotes normal nerve and muscle activityIncreases contraction of myocardiumMaintains normal cellular permeability and promotes blood clottingConverts prothrombin into thrombinVit D necessary for calcium absorption in GI tract

CalciumHypocalcemiaHypercalcemiaCa 10.5 mg/dLResults from hyperparathy-roidism, low PO4, prolonged immobilization, multiple fxs/sx include:Flabby muscles, pain over bony areas, kidney stonesTreatment: correct the underlying causeHypocalcemiais abnormally low calcium concentration in the blood. The physiologically active form of calcium in the blood is ionized calcium. Total blood889890calcium also contains inactive forms that are bound to plasma proteins and small anions such as citrate. Factors that cause too much ionized calcium to shift to the bound forms cause symptomaticionized hypocalcemia.Table 41-5summarizes general causes. People who have acute pancreatitis frequently develop hypocalcemia because calcium binds to undigested fat in their feces and is excreted. This process decreases absorption of dietary calcium and also increases calcium output by preventing resorption of calcium contained in GI fluids. Hypocalcemia increases neuromuscular excitability, the basis for its signs and symptoms.

Hypercalcemiais abnormally high calcium concentration in the blood. Hypercalcemia results from increased calcium intake and absorption, shift of calcium from bones into the ECF, and decreased calcium output (seeTable 41-5). patients with cancer often develop hypercalcemia because some cancer cells secrete chemicals into the blood that are related to parathyroid hormone. When these chemicals reach the bones, they cause shift of calcium from bones into the ECF. This weakens bones, and the person sometimes develops pathological fractures (i.e., bone breakage caused by forces that would not break a healthy bone). Hypercalcemia decreases neuromuscular excitability, the basis for its other signs and symptoms, the most common of which is lethargy29Magnesium (Mg)Normal value: 2.0 3.0 mg/dLPromotes transmission of neuromuscular activityImportant mediator of neural transmission in CNSAlso promotes myocardial contractionTransports Na+ and K+ across cell membranes

MagnesiumHypomagnesemiaHypermagnesemiaMg < 2.0 mg/dLFrequently coincides with K+ or Ca+ deficitGenerally asymptomatic until level is < 1.0 mg/dLTreatment: IV replacementMg > 3.0 mg/dLResults from excess intake of magnesium salts (laxatives, MOM, Maalox, Mylanta)AsymptomaticTreatment: termination of mag salt intake, admin of calcium gluconate

Hypomagnesemiais abnormally low magnesium concentration in the blood. Its general causes are decreased magnesium intake and absorption, shift of plasma magnesium to its inactive bound form, and increased magnesium output (seeTable 41-5). Signs and symptoms are similar to those of hypocalcemia because hypomagnesemia also increases neuromuscular excitability.

Hypermagnesemiais abnormally high magnesium concentration in the blood (seeTable 41-5). End-stage renal disease causes hypermagnesemia unless the person decreases magnesium intake to match the decreased output. Signs and symptoms are caused by decreased neuromuscular excitability, with lethargy and decreased deep tendon reflexes being most common.

31Phosphorus (PO4)Normal value: 2.0 2.6 mEq/LMostly found in association with calciumEssential in bone and teeth formation, and for neuromuscular activityImportant component of DNA and RNAAssists in cell energy transfer, acid-base balance, and osmotic pressure

PhosphorusHypophosphatemiaHyperphsphatemiaPO4 < 2.0 mEq/LResults from GI abnormalities, hormonal changes (shock, surgery), malabsorptions/sx include:Muscle weakness, tremors, paresthesia, bone painTreatment: IV replacementPO4 > 2.6 mEq/LResults from renal insufficiency or failure, increased intake of phosphate medicationss/sx include:Hyperreflexia, tetany (with decreased Ca), weakness, tachycardiaTreatment: Treat underlying causeNCLEX PracticeThe family of a client with chronic hyponatremia asks if the water restriction is a punishment for his uncooperative behavior. What is the nurses best response?A. No, limiting fluid intake decreases the risk for kidney failure.B. No, limiting water intake prevents him from losing too much fluid by vomiting.C. No, limiting fluid intake keeps his blood from becoming more dilute and causing other complications.D. No, limiting fluid decreases his sense of thirst and prevents him from drinking liquids that contain an excess of sodium.NCLEX PracticeA client has been taught to restrict dietary sodium. Which food selection by the client indicates to the nurse that teaching has been effective?A. Chinese take-out, including steamed riceB. A grilled cheese sandwich with tomato soupC. Slices of ham and cheese on whole grain crackersD. A chicken leg, one slice of bread with butter, and steamed carrots

NCLEX PracticeThe nurse assesses distended neck veins in a client sitting in a chair to eat. What intervention is the nurses priority?A. Document the observation in the chart.B. Measure urine specific gravity and volume.C. Assess the pulse and blood pressure.D. Assess the clients deep tendon reflexes.

Case Study/Concept MapMrs. Hilda Beck is a 72-year-old being seen by her health care provider this morning. She fell this morning after becoming light-headed. She has had several episodes of vomiting and diarrhea over the last 2 days. She was admitted for oral and IV fluid therapy.Case Study/Concept MapWhy is Mrs. Beck likely becoming light-headed? When should you expect this to resolve?

What type of fluid (isotonic, hypotonic, hypertonic) would you expect the physician to order?

Mrs. Becks IV fluid order is 1000 ml 0.9% sodium chloride to run over 8 hours. Calculate the milliliters per hour (ml/hr) you should program into her pump.Case Study/Concept MapYou auscultate crackles in Mrs. Becks lung bases while her IV is infusing. What do you now suspect?

The physician has diagnosed Mrs. Beck with gastroenteritis & dehydration. Create a concept map.39