fluid & electrolytes acid base imbalances chapter 17

FLUID & ELECTROLYTESACID BASE IMBALANCES

CHAPTER 17

Megan McClintockWinter 2012

HOMEOSTASIS Maintained by the intake and output of water

and electrolytes and regulation by the renal and pulmonary systems

Acid-base balance is necessary for many physiologic processes (respiration, metabolism, function of the CNS)

Many disease and treatments affect this balance

WATER More important to life than any other

nutrient 60% of an adult’s body weight, more in

a child, less in the elderly Found in foods (but not in alcohol) Daily need is about 2000 mL 1 liter of water weighs 1 kg

URINE SPECIFIC GRAVITY

Measures the kidney’s ability to concentrate or dilute urine

1.002 – 1.028 High is dehydrated Low is overhydrated (or unable to

concentrate) Kidney failure often causes a fixed specific

gravity

ELECTROLYTES Cations (positively charged)

K+, Na+, Ca+, Mg+ Transmit nerve impulses to muscles and

contract skeletal and smooth muscles Anions (negatively charged)

Attached to cations Cl-, HCO3-, PO4-, SO4-

Are always kept in balance

DISTRIBUTION OF BODY FLUIDS & ELECTROLYTES

Intracellular (2/3) – K+, PO4- Extracellular (1/3) – Na+, Cl-

Interstitial (lymph) Intravascular (blood plasma) Transcellular (cerebrospinal, pleural,

peritoneal, synovial fluids)

REGULATION OF FLUID & ELECTROLYTE MOVEMENT

OSMOLALITY Indicates the water balance of the body Serum osmolality (275 - 295)

High is water deficit Low is water excess

Urine osmolality (100-1300) High is concentrated Low is dilute

FLUID SPACING First spacing

Normal Second spacing

Edema Third spacing

Ascites Burn edema

REGULATION OF WATER BALANCE Hypothalmic Regulation

Thirst is stimulated ADH (vasopressin) release is stimulated

Pituitary Regulation ADH (vasopressin) is released

Adrenal Cortical Regulation Glucocorticoids & mineralocorticoids are released

Renal Regulation Adjust urine volume and electrolyte excretion Normal is 1.5 Liters of urine/day

REGULATION OF WATER BALANCE (CONT.) Cardiac Regulation

ANP & BNP will stop the action of the adrenal cortex and the kidney

GI Regulation Intake and output are reabsorbed here Diarrhea and vomiting can lead to significant

losses Insensible Water Loss

600-900 mL/day from the lungs and skin Increases with fever, exercise

GERONTOLOGIC CONSIDERATIONS Structural changes in the kidney and decreased

renal blood flow Decreased GFR Decreased creatinine clearance Loss of ability to concentrate urine and thus conserve

water Decrease in renin and aldosterone Increase in ADH and ANP

Loss of subcutaneous tissue Decrease in thirst mechanism Musculoskeletal changes Mental status changes Incontinence

FLUID VOLUME DEFICIT

What causes it?

What can you do?

FLUID VOLUME EXCESS

What causes it?

What can you do?

NURSING INTERVENTIONS Strict I/O

Intake – oral, IV, tube feedings, retained irrigants Output – urine, excess sweating, wound/tube

drainage, vomitus, diarrhea Urine specific gravity Assessment of CV, Resp, Neuro, Skin status Daily weight under standardized conditions Don’t “catch up” IV fluids No water with NG suction, use isotonic saline Keep fluids accessible and within reach Give warm or cold fluids (not room temperature)

SERUM ELECTROLYTES Sodium (Na) 135 - 145

Primarily responsible for maintaining osmotic pressure (intracellular and extracellular fluids)

Increased with fluid deficit Decreased with fluid excess

Potassium (K) 3.5 – 5.0 Major component of cardiac function Increased with poor kidney function Decreased with excessive urination, diarrhea or vomiting

Chloride (Cl) 96 – 106 Works with Na to maintain osmotic pressure Increased with poor kidney function Decreased with excessive vomiting or diarrhea

Calcium (Ca) 8.6 – 10.2 Transmission of nerve impulses, heart and muscle

contractions, blood clotting, formation of teeth and bone Phosphate (PO4) 2.4 – 4.4

Function of muscle, RBCs, and the nervous system

THE MAGIC FOURS

Electrolyte Range Magic 4Potassium 3.5 - 5.0 4Chloride 96 - 106 104Sodium 135 - 145 140pH 7.35 - 7.45 7.4CO2 35 - 45 40HCO3 22 - 26 24

Hematocrit normal is 3 times the hemoglobin

SODIUM (135 - 145) Major cation of ECF Primary determinant of osmolality GI tract absorbs sodium from food Regulated by kidneys, ADH,

aldosterone Sodium level reflects the ratio of

sodium to water Imbalances are typically associated

with fluid volume problems

HYPERNATREMIA (HIGH SODIUM)

What can you do?

What causes it?

HYPONATREMIA (LOW SODIUM)

What causes it?

What can you do?

POTASSIUM (3.5 - 5.0) Major cation of ICF Sodium-potassium pump requires

magnesium Moves into cells during formation of

new tissues and leaves the cell during tissue breakdown

Diet is the source of potassium Kidneys are primary route of loss

HYPERKALEMIA (HIGH POTASSIUM)

What can you do?

What causes it?

HYPOKALEMIA (LOW POTASSIUM)

What causes it?

What can you do?

CALCIUM (8.6 – 10.2) Primary source is bones Regulated by parathyroid hormone,

calcitonin, and vitamin D Affects transmission of nerve impulses,

heart and muscle contractions, blood clotting, and forming of teeth and bone

HYPERCALCEMIA (HIGH CALCIUM)

What can you do?

What causes it?

What are the

symptoms?

HYP0CALCEMIA (LOW CALCIUM)

PHOSPHATE IMBALANCES Hyperphosphatemia

Cause - renal failure S/S – calcium deposits in joints, skin, kidneys, eyes;

hypocalcemia, tetany, neuromuscular irritability Tx – decrease intake of dairy products, good hydration, fix

hypocalcemia Hypophosphatemia

Cause – malnutrition, malabsorption syndrome, alcohol withdrawal

S/S – CNS depression, confusion, muscle weakness, dysrhythmias

Tx – oral supplements (Neutra-Phos), lots of dairy products, IV phosphate (but this can cause sudden hypocalcemia)

MAGNESIUM IMBALANCES Hypermagnesemia

Cause – increased intake (ie. MOM, Maalox) with chronic kidney disease

S/S – lethargy, n/v, loss of DTRs, can have respiratory and cardiac arrest

Tx – avoid magnesium-containing drugs, IV calcium, increased fluid intake, may need dialysis

Hypomagnesemia Cause – prolonged fasting or starvation, chronic alcoholism,

diuretics S/S – confusion, hyperactive DTRs, tremors, seizures, cardiac

dysrhythmias Tx – oral supplements, increase green veggies, nuts, bananas,

oranges, peanut butter, chocolate; IV or IM magnesium (if given too rapidly can cause cardiac or respiratory arrest)

MEDICATIONS Loop diuretics Thiazide diuretics Potassium sparing diuretics Electrolytes Kayexolate

ACID BASE BALANCE

REGULATION OF ACID-BASE BALANCE Buffer system (immediate)

Primary regulator Won’t work without good functioning

respiratory and renal symptoms Respiratory system (minutes, max in

hours) Excretes CO2 and water

Renal system (2-3 days to max respond) Reabsorbs HCO3

ARTERIAL BLOOD GAS pH (7.35 – 7.45) CO2 (35 – 45) HCO3 (22 – 26) Base excess (+2 to -2)

If high, metabolic alkalosis If low, metabolic acidosis

DETERMINING ACID–BASE BALANCE

1. Is pH acid, base or normal?2. Is CO2 acid, base or normal? 3. Is HCO3 acid, base or normal?4. Which of the components match?5. Is there compensation?

Is non-matching reading abnormal? – partial compensationIs non-matching reading normal? – no compensation

RESPIRATORY ALKALOSIS

RESPIRATORY ALKALOSIS Causes

Hyperventilation Pulmonary disease High altitudes

Signs/symptoms Hyperventilation Feels “light-headed” Arrhythmias Anxiety

Treatment Breathe into paper bag Rebreather mask Anti-anxiety medicine Relaxation techniques Reduce stimulation Treat pain/fever Assess:

Resp rate/depth HR & BP Serum K levels Hydration status Check for digitalis toxicity

RESPIRATORY ACIDOSIS

RESPIRATORY ACIDOSIS Causes

CNS depression Loss of lung surface Neuromuscular disease Immobility Mechanical ventilation

Signs/symptoms Dyspnea Hypoxia Drowsiness Tachycardia Seizures Diaphoresis

Treatment Turn, cough, deep breathe Semi-Fowler’s position Suction Incentive spirometer Seizure precautions Decrease use of sedatives Bronchodilators May need ventilator Assess:

Resp rate/depth HR & BP Patiency of airway

METABOLIC ALKALOSIS

METABOLIC ALKALOSIS Causes

NG suctioning Prolonged vomiting Diuretic use Multiple blood transfusions CPR (given bicarb)

Signs/symptoms Dizziness Dysrhythmias Convulsions Confusion Muscle cramps (late sign)

Treatment Identify and treat the cause! IV fluids Stop giving bicarbonate Give antiemetics Give Diamox Assess:

Resp rate/depth HR & BP Serum K levels (usually low) Hydration status (tend to be

dehydrated) Check for digitalis toxicity Parasthesias

METABOLIC ACIDOSIS

METABOLIC ACIDOSIS Causes

Diabetic ketoacidosis Renal or liver failure Severe diarrhea Vomiting Starvation

Signs/symptoms Kussmaul respirations Hypotension Arrythmias Warm to hot ,flushed skin Confusion

Treatment Identify and treat the

cause! Administer insulin (if due to

ketoacidosis) Give antiemetics IV fluids IV bicarbonate Assess:

Renal function (BUN, creatinine)

Serum K levels (tends to go up but down once insulin given)

Hydration status

IV FLUIDS Isotonic

NS D5W LR

Hypertonic 3% NS D51/2NS D10W

Hypotonic 1/2NS

Plasma Expanders

CENTRAL VENOUS ACCESS DEVICES Centrally inserted

catheters (CVCs)

Peripherally inserted central catheters (PICCs)

Implanted infusion ports

NURSING CARE OF CVADS Inspect site for redness, edema, warmth, drainage, pain Dressing change/cleaning with sterile technique using

chlorhexidine (back and forth scrub to generate friction) Maintain transparent dressing c/d/I Change injection caps using sterile technique Teach pt to turn head away from insertion site during

cleaning and cap change Have patient Valsalva during cap change if unable to

clamp Use push-pause method to flush (creates turbulence) Removal of non-tunneled CVCs and PICCs may be done

by a trained nurse (have pt Valsalva as last of catheter is withdrawn, apply pressure immediately, inspect catheter tip)