Fluids & Electrolytes and Acid Base Balance

Med-Surg

Fluid & Electrolyte Balance

• Fluid balance is closely linked to and affected by electrolyte concentrations

• Age, sex, and amount of fat affect the distribution of body fluids

Functions of Water

• Transports nutrients, gases, & wastes into and out of cells

• Facilitates elimination of wastes via kidneys, gastrointestinal tract, skin, & lungs

• Regulates body temperature through evaporation from the skin

Filtration

• Movement of water through a cell or membrane because of hydrostatic pressure

Diffusion

• Movement of particles across a permeable membrane from an area of higher
  concentration to an area of lower concentration

Osmosis

• Movement of water through a semipermeable membrane

• Water moves by osmosis from a dilute fluid (fewer particles) to a more concentrated fluid until equilibrium is achieved

Osmolarity

• Is the number of milliosmoles in one liter of fluid

• Normal osmolarity is 270-300 mOsm/L

Osmolality

• Is the number of milliosmoles in one kilogram of fluid

• 1L=1Kg

• Aldosterone

• Antidiuretic hormone

• Natriuretic peptides

What hormones influence fluid output

Renin Angiotensin Aldosterone System

Maintains blood pressure

.1. Renin

• Kidneys respond to drop in BP by secreting renin

• Low BP & Low circulation is sensed by the kidneys

2. Angiotensinogen

• is produced by the liver, is coverted, by renin into Angiotensin I

3. Angiotensin I

4. Angiotensin Coverting Enzyme (ACE)

• converts angiotensin I into angiotensin II

5.Angiotensin II

• Stimulates peripheral vasoconstriction which increased blood pressure

• Stimulates adrenal glands to release aldosterone

6. Aldosterone

• High

Dehydration

• Fluid intake or retention is less than what is needed to meet the body’s fluid
  needs

• Actual decrease in total body water

• Vascular dehydration: water shifts from the plasma into the interstitial space (third spacing)

• Isotonic dehydration most common type of fluid loss problem

• Dehydration is important to know due to: hypovolemia and decreased tissue perfusion

Risk factors of Dehyrdation

• Older Adults/pediatrics

• Hemorrhage

• Vomiting

• Diarrhea

• Profuse Diaphoresis (sweating)

• Burns

• Severe Wounds

• Fistulas

• Long-term NPO

• Diuretic Therapy

• GI suction

• DI (diabetes inspipidus)

• Fever

• Impaired Motor Function

Manifestations of Dehydration

• Decreased blood pressure

• Elevated heart rate

• Weak peripheral pulses

• Orthostatic hypotension

• Poor skin turgor

• Dry scaly skin

• Dry, sticky mucus membranes

• Urine output less than 500 ml/day or 20 ml/hour

• Weight loss of over half a pound/day

Diagnostic Studies of Dehydration

• High Sodium (normal 136-145)

• High potassium (normal 3.5-5.0)

• Elevated hemoglobin, hematocrit, serum osmolarity, glucose, protein, and BUN

• Hemoconcentration

Priority Problems for Dehydration

• Disrupted Fluid and Electrolyte Balance

• Potential for Decreased Tissue Perfusion

Planning/Implementation for Dehydration

Mild to Moderate:

• Oral fluid replacement

• Delegate to the UAP 60-120 ml/hr

• Oral rehydration solutions with glucose and electrolytes

Severe:

• IV Fluid Replacement

Colloids IV Fluids

• Includes Albumine, Dextran, Hydroxyethyl starches (HES), Gelatin

• Large molecules that stay in intravascular space longer

• Fast at expanding intravacular space & amount administered equal to amount lost

• Risk: allergic reaction, coagulation problems

• Cost More

Crystalloids IV Fluids

• Include Hypotonic, Hypertonic, Isotonic solutions

• Small molecules that dont stay too long in intravascular space

• High amount of fluids needed to equal amount lost (overload: edema)

• No allergic reaction or coagulation problems

• Cost Less and easier to access

Hypotonic Solutions

• IV fluid with osmolarity lower than blood. Moves fluid out of blood vessels into cells nd interstitial spaces

• Indications: DKA, HHNS, & Hypernatremia

• EX

- 0.45% Sodium Chloride (1/2 Normal Saline)

- 0.33% or 0.2% Sodium Chloride

- 2.5% Dextrose in Water (D2.5W)

- 5% De

Isotonic Solution

• IV fluid with osmolarity similar to blood. Expand intravascular fluid volume and do not cause shift in fluid.

• Indications: blood loss, surgert, isotonic dehydration, fluid loss, maintenance fluids, npo pts

• EX

-- lactated ringers

— 0.9% Sodium Chloride (NS)

— D5W

Hypertonic Solution

• IV fluid with osmolarity higher than blood. Moves fluid out of cells and interstitial spaces into blood vessels

• Indications: Hyponatremia, Cerebral edema

• EX

— 1.5%, 3% or 5% Sodium Chloride

— D5NS

— D5LR

— D10W

Drug Therapy

• Antidiarrheal drugs

• Antimicrobials

• Antiemetics

• Antipyretics

Preventing Injury

• Monitor Vitals signs

• Prevent falls

Evaluating outcomes of Dehydration

• Maintains fluid intake of at least 1500 ml or 500 ml more than output

• Maintains blood pressure at or near the patient’s normal

• Moist mucous membranes and normal skin turgor

Fluid Volume Overload

• Excess of body fluid

• Caused by: excessive intake or inadequate excretion of
  fluids (See Box 13.1)

• Hypervolemia
  — Excessive fluid in the extracellular fluid space
  — Excessive fluid in the vascular space or dilution of electrolytes

• Severe FVO → heart failure and pulmonary edema

• Dilution of sodium and potassium → seizures, coma, death

Risk Factors for Fluid Overload

• Excessive fluid replacement

• Kidney Failure

• Heart Failure

• Long-term steroid replacement

• SIADH

• Water Intoxication

• Psychiatric disorders

Manifestations of Fluid Overload

• Increased pulse rate

• Bounding pulses

• Elevated blood pressure

• Distended neck and hand veins

• Weight gain

• Increased respiratory rate

• Shallow respirations

• Shortness of breath

• Moist crackles

• Pitting edema

• Pale, cool skin

Diagnostic Studies

• Low Sodium (normal:136-145)

• Low Potassium (normal:3.5-5.0)

• Low Chloride (normal:98-108)

• Decreased hemoglobin, hematocrit, serum osmolarity, and protein

• Hemodilution

Priority Problems of Fluid Overload

• Patient Safety

• Restore Fluid Balance

• Prevent Future Fluid Overload

Planning/Implementation for Fluid Overload

Drug Therapy:
• Remove excess fluid – diuretics

Nutrition Therapy:
• Fluid and Sodium restriction
• Monitor food labels and keep a record

Monitoring:
• Intake and output
• Rapid Weight gain

Intake & Outpute

Intake:

• Oral intake

• IVPB intake

• Continuous IV fluid

• Irrigations

• Tube feedings and flushes

• IV flushes

Output

• Urine output

• Emesis

• Chest tubes

• Surgical drains (JP drains, hemovac, etc.)

• Nasogastric tube output

• Ostomy output

Key reminders:

• Measure all output in mL

• Do the math for continuous fluids! (100mL/hr x 8 hours = 800mL)

• Add all amounts for intake and output to get shift totals

• Intake total - Outtake total = Net I&O Fluid Status (+) or (-)

Sodium (Na)

• Major cation in the Extracellular Fluid

• Vital for
  — Muscle Contraction
  — Cardiac Contraction
  — Nerve Impulse Transmission

• Influences water balance

• Often enters the body through foods and fluids

• Hyponatremia <136 mEq/L (less than 136)

• Hypernatremia >145 mEq/L ( greater than 145)

Na+ = 135-145

Risk factors for Hyponatremia

Loss of body Na

• GI fluid loss (V/D)

• Diuretics

• Severe burns

• ↓ Aldosterone

• Renal disease
  

Dilution of Na

• Excess water intake

• Renal failure

• Hypotonic fluid irrigations

• SIADH

• Heart failure

• Liver failure/ cirrhosis

Manifestations of Hyponatremia

Cerebral edema
•Altered LOC•
Seizures
•Death

Neuromuscular changes
•Muscle weakness
• ↓ DTR (deep tendon reflex)

Intestinal/ GI changes
• ↑ motility (bowel sounds?)
• N/D
•Cramping

Cardiovascular changes
• *depends on the cause:

• Na+Hypovolemia: Weak, thready pulses; ↓BP; dizzy; lightheaded (fluid volume defecit)

• Na+Hypervolemia (dilutional): Bounding pulses; normal/high BP

Interventions (Action) for Hyponatremia

Interventions depend on the CAUSE

Drug Therapy: Give slow

• Decrease/change diuretics

• 0.9% sodium chloride infusion

• 3% sodium chloride**

• Vasopressin (ADH) receptor antagonists
  

Nutrition Therapy

• Increased sodium oral intake

• Restricting oral fluid intake

Risk factors of Hypernatremia

Actual Na Excess

• Excess Na intake (oral or IV)

• Renal failure

• Hyperaldosteronism
  

Relative Na Excess (concentration)

• Dehydration

• Fever

• Excessive diaphoresis

• Watery diarrhea

Manifestations of Hypernatremia

Cerebral Changes

• Agitation
• Confusion
• Lethargy →stupor →coma

Musculoskeletal changes
• Muscle twitching
• Progressive weakness
• Absent DTR

Cardiovascular changes
• *Depends on the cause

• Na+Hypovolemia: Weak, thready pulses; ↓BP; dizzy; lightheaded (fluid volume defecit)

• Na+Hypervolemia (dilutional): Bounding pulses; normal/high BP, JVD (fluid volume overload)

Interventions (Actions) for Hypernatremia

Interventions depend on the CAUSE

Drug Therapy:

• 0.9% sodium chloride infusion

• Hypotonic solutions

• Diuretics
  
  

Nutrition Therapy

• Promoting adequate oral water intake

• Oral sodium restriction

Potassium (K)

• Major cation of the Intracellular Fluid

• Vital for excitable tissues

• Small changes = significant effect

• Regulated by the sodium-potassium pump and
  adequate magnesium levels

• 80% of K is removed by the kidneys

• Potassium is Excitable, removed by the kidneys

• Hypokalemia < 3.5mEq/L (less than 3.5)

• Hyperkalemia >5 mEq/L (greater than 5)

Risk Factors for Hypokalemia

Actual K Deficit

• Diuretics

• D/V

• Gastric suction

• Wound drainage

• ↑ Aldosterone

• Inadequate intake

Relative K Deficit

• Alkalosis

• Hyperinsulinemia and insulin infusions

• TPn

• Hypomagnesemia

Manifestations of Hypokalemia

Age Impact*

Respiratory changes

• Muscle weakness

• Shallow respirations
  
  

Musculoskeletal changes

• Muscle weakness

• Flaccid paralysis

Cardiovascular changes
•Weak, thready pulses
•Cardiac dysrhythmias
•ECG changes:
•ST depression
•U wave
•Orthostatic hypotension

Neurological

• AMS, irritability, coma
  
  

Gastrointestinal changes

• ↓motility → paralytic ileus

Interventations (Action) for Hypokalemia

Is LIFE THREATENING

Drug Therapy:

• Potassium replacement

• Oral supplements

• IV potassium *HIGH ALERT

• K Sparing diuretics
  
  

Nutrition Therapy
• Potassium rich foods

Safety
• ECG monitoring
• Fall precautions
• Respiratory monitoring

Risk Factors of Hyperkalemia

Actual K Excess

• Excess intake (PO, IV, salt substitutes)

• Renal failure*

• K-sparing diuretics,ACEi
  

Relative K Excess

• Massive tissue damage (Crush syndrome)

• Acidosis

• Uncontrolled DM

Manifestations of Hyperkalemia

Age Impact*
Cardiovascular changes**

• Bradycardia

• Hypotension

• Cardiac dysrhythmias

• Vfib, asystole
  

ECG changes:

• Tall peaked T waves

• Prolonged PR intervals

• Wide QRS
  

Neuromuscular changes
•Muscle twitching → paresthesia
•Weakness → Flaccid paralysis
•Respiratory muscles not impacted until K levels are lethal

Gastrointestinal changes
• ↑motility, diarrhea, frequent stools

Interventions (Actions for Hyperkalemia

is a COMMON CAUSE OF DEATH

Drug Therapy:
• Potassium replacement
• Oral supplements
• IV potassium *HIGH ALERT
• K Sparing diuretics

Nutrition Therapy
• Potassium rich foods

Safety
• ECG monitoring
• Fall precautions
• Respiratory monitoring

Calcium (Ca2)

• Important for
  — Bone Strength and Density
  — Activating Enzymes
  — Skeletal and Cardiac Muscle Contraction
  — Controlling Nerve Impulses
  — Blood Clotting

• Enters the body by dietary intake and absorption through the intestine

• Requires Vitamin D for absorption

• Regulated by the Parathyroid hormone (PTH)

• Cell membrane stabilizer

• Hypocalcemia < 9mg/dL (less than 9)

• Hypercalcemia > 10.5mg/dL (greater than 10.5)

Risk factors for Hypocalcemia

Actual Ca Deficit
• Inadequate intake
• Inadequate VitD intake
• ESRD
• Diarrhea

Relative Ca Deficit
• Alkalosis
• ↑ Phosphorus
• Acute pancreatitis
• ↓ PTH

Manifestations for Hypocalcemia

Neuromuscular changes
•Paresthesia hands and feet
•Muscle twitching, spasms, tetany
•Seizures*
•Trousseau sign (hand)
•Chvostek sign (cheek)

Cardiovascular changes**
• HR
• Weak, thready pulses
• Severe hypotension
•ECG changes:
•Prolonged ST interval
•Prolonged QT interval

Gastrointestinal changes
• ↑motility, diarrhea, cramping

Skeletal changes
• ↓ bone density
• Brittle, fragile bones; ↓ height

Interventions (Action) for Hypocalcemia

Drug Therapy:
• Calcium replacement (PO, IV)
• Vitamin D supplementation

Nutrition Therapy
• Ca and VitD rich foods
• Low phosphorus diet (low red meats)

Safety
• ECG monitoring**
• Low stimulation room

Risk Factors for Hypercalcemia

Actual Ca Excess
• Excess intake
• CKD
• Thiazide diuretics

Relative Ca Excess
• Hyperparathyroidism
• Malignancy
• Immobility**
• Dehydration

Manifestations for Hypercalcemia

Cardiovascular changes**
• Mild: ↑ HR & BP
• Severe: bradycardia
• Poor perfusion
• Thrombosis

Neuromuscular changes
•Muscle weakness
•↓DTR
•Confusion and lethargy

Gastrointestinal changes
• ↓motility
•Nausea, vomiting, constipation,
distention

Intervnetions (Actions) for Hypercalcemia

Drug Therapy:
• Stop all contributing meds
• Fluid replacement (NS)**
• Diuretic (Loops)**

Prevention meds:
• Calcitonin, bisphosphonates,and prostaglandin synthesis inhibitors

Safety
• ECG monitoring**
• Fall risk

Magnesium (Mg)

• Mostly stored in bones and cartilage

• Important for
  — Skeletal muscle contraction
  — Carbohydrate metabolism
  — Generation of energy stores
  — Vitamin activation
  — Blood coagulation
  — Cell growth
  —Health and maintenance of cardiac muscle

• Regulated by potassium and calcium levels

• Magnesium is a relaxant*

• Hypomagnesmia < 1.3 mEq/L (less than 1.3)

• Hypermagnesemia > 2.1 mEq/L (greater than 2.1)

Risk Factors for HypoMagnesemia

• Inadequate intake

• Mg wasting diuretics

• When Mg is low, Ca and K are often also low.
  — This further increases the risk for cardiac dysrhythmias

Assessments for Hypomagnesemia

Cardiovascular changes
• HTN
• Cardiac dysrhythmias
• Ventricular fibrillation
• Long QT intervals

Neuromuscular changes
• Numbness, tingling, spasms
• Hyperactive reflexes
• Tetany and seizures

Intestinal changes
• ↓ motility
• Constipation

Implementation for Hypomagnesemia

Discontinue causative agent
• Mg wasting diuretics

Drug therapy
• Magnesium replacement (PO, IV)
• Ca and K correction

Risk Factors of Hypermagnesemia

• Rare**

• Excessive intake (PO, IV)

• Renal failure

Assessment for Hypermagnesemia

Symptoms begin > 4.0

Cardiac changes
• Bradycardia
• Vasodilation
• Hypotension
• Cardiac Arrest

Central Nervous System
• Drowsiness →lethargy →coma

Neuromuscular
• Absent reflexes
• Weak respiratory muscles
• Respiratory failure

Implementations for Hypermagnesemia

• Discontinue all Mg Drug Therapy

• IV fluids

• Diuretics (loops)

• Calcium replacement

Acid Base Balance

• If a lung problem causes retention of carbon dioxide, the kidney compensates by increasing the amount of bicarbonate that is produced and retained

• Acidosis decreases the excitability of the cardiovascular muscles, neurons, skeletal muscle, and GI smooth muscles

• Alkalosis increases the sensitivity to excitable tissues, overresponding to normal stimuli

Acidosis

• is caused by too much acid (pH < 7.35) not enough base

• Acid Excess

- Older adults with chronic health problems DKA, prolonged seizures, severe hypoxia
Respiratory and renal failure

• Base Deficit

- Pancreatitis
- Dehydration
- Diarrhea

• Acidosis leads to hyperkalemia which triggers: Musculoskeletal, cardiac, respiratory, and CNS symptoms

Risk Factors for Respiratory Acidosis

• Respiratory depression

• Anesthetics

• Opioids

• Electrolyte imbalance

• Muscle weakness

• Airway obstruction

• Alveolar-capillary block

Manifestations of Respiratory Acidosis

Cardiovascular changes

• ↑HR and CO → ↓HR, ↓BP,

• vasodilation

CNS changes

• Lethargy, confusion → unresponsive

Neuromuscular changes

• Muscle weakness → paralysis

Respiratory changes

• Ineffective, shallow, rapid
  

Skin Changes

• Pale and cyanotic

Laboratory Studies for Respiratory Acidoses

• ABGs

• pH < 7.35

• PaO2 < 90

• PaCo2 > 50

• Bicarbonate 21-28

• K ↑ ↓ OR Normal

Respiratory Acidosis Improve Gas Exchange Implementation

• Drug Therapy
  • Bronchodilators, anti-inflammatories, and mucolytics

• Oxygen Therapy & Ventilatory Support

• Monitoring
  • Breathing status, breath sounds, and accessory muscles
  • Nail beds, cyanosis

Risk factors for Metabolic Acidosis

Overproduction of hydrogen ions
• DKA
• Starvation

Hypermetabolism
• Excessive ingestion of acids

Under elimination of hydrogen ions
• Kidney Failure

Underproduction of bicarbonate
• Kidney Failure

Over elimination of bicarbonate
• Diarrhea

Manifestations for Metabolic Acidosis

Same as Respiratory Acidosis…Plus
• Kussmaul respirations (deep breaths releasing CO2)
• Warm and dry with reddish undertones

Laboratory Studies for Metabolic Acidosis

• ABGS

• pH < 7.35

• PaO2 80-100

• paCO2 35-40

• Bicarbonate 15-20

• K ↑

Metabolic Acidosis Planning and Implementation

• Hydration

• Drug Therapy to control the underlying problem

• IV Bicarbonate for pH < 7.2

• Cardiovascular and Musculoskeletal System monitoring

• Interpret ongoing ABGs

Interpreting Arterial Blood Gases (ABGs) Respiratory Opposite Metabolic Equal (R.O.M.E)

Normal

• Assess pH: 7.35-7.45

• Evaluate PaCO2: 35-45

• Evaluate HCO3: 22-26

Acidosis

• Assess pH: <7.35 (less than)

• Evaluate PaCO2: >45 (greater than)

• Evaluate HCO3: <22 (less than)

Alkalosis

• Assess pH: >7.45 (greater than)

• Evaluate PaCO2: <35 (less than)

• Evaluate HCO3: >26 (greater than)

• Determine Compensation: Is the opposite system trying to correct the imbalance?

• Assess PaO2 & SaO2: What is the O2 status?

Alkalosis

• pH > 7.45; is caused by too much base or not enough acid

• Base Excess
  — Oral ingestion: Antacids
  — Parenteral infusions – TPN, sodium bicarb

• Excessive CO2 Losses
  — Hyperventilation
  — High altitude

• Acid Deficit
  — Prolonged vomiting
  — NG tube suctioning
  —Diuretics
  

Metabolic Alkalosis

• Increase in bases or decrease in acids

• ABG

• pH >7.45 and HCO3 > 26

Respiratory Alkalosis

• Excessive loss of CO2

• ABG

• pH > 7.45 and CO2 < 35

Symptoms of Alkalosis

• CNS Symptoms
  — Anxiety, irritability, tetany, seizures

• Neuromuscular Symptoms
  — Hyperreflexia, muscle cramping, and muscle weakness

• Cardiovascular Symptoms
  — Increased heart rate, low blood pressure

• Respiratory Symptoms
  — Hyperventilation (respiratory alkalosis)
  — Decreased respiratory efforts (metabolic alkalosis)

• Symptoms result from hypocalcemia and hypokalemia

Alkalosis Planning and Implementation

Prevent further loss of H+, K+, Ca²+, and Cl- ions
• Stop therapies
• Breathe into a paper bag
• Oxygen therapy

Restore fluid balance
• IV fluids
• Antiemetics

Monitor for changes
• Electrolytes

Patient Safety
• Fall Precautions