Fluid Imbalance

Electrolytes

• Substances that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent.

• Positively and negatively charged ions that:

  • • Deliver nutrients • Take away waste

  • (Groceries in Garbage out)

Solutes: particles dissolved in fluid

• Electrolytes • Albumin

Solvent: fluid

• Extracellular fluid (lntravascular)

• Intracellular fluid

• Interstitial fluid

Fluid Compartments

ICF: Contained in cell. This fluid volume tends to be very stable, because the amount of water in living cells is closely regulated. If the amount of water inside a cell falls to a value that is too low, it becomes too concentrated with solutes to carry on normal cellular activities; if too much water enters a cell, the cell may burst and be destroyed.

ECF: Plasma travels through the body in blood vessels and transports a range of materials, including blood cells, proteins (including clotting factors and antibodies), electrolytes, nutrients, gases, and wastes.

Fluid Compartments

Total Body Water

• Human beings are mostly water, ranging from about 75 percent of body mass in infants to about 50-60 percent in adult men and women, to as low as 45 percent in old age. Your brain and kidneys have the highest proportions of water, which composes 80-85 percent of their masses. In contrast, teeth have the lowest proportion of water, at 8-10 percent.

• ICF = 40% TBW

• ECF = 20% TBW

  • ISF = (filtrate of blood) Not much water. Some Na+ Except in inflammation (80% of ECF)

  • IVF = Plasma volume (20% of ECF)

Osmosis

• Movement of fluid (solvent) from an area of lesser concentration to an area that is more concentrated. "Dilution to create equilibrium"

Diffusion

• Movement of molecules (solutes) from an area of higher concentration to lower concentration

Active, Facilitated and Passive Transport

Central Idea

Transport of molecules across cell membranes

Main Branches

1. Active Transport

2. Facilitated Transport

3. Passive Transport

Active Transport

• Definition: Movement of molecules against the concentration gradient, requiring energy

• Types:

  • Primary Active Transport

  • Secondary Active Transport

• Examples:

  • Sodium-Potassium Pump

  • Calcium Pump

Facilitated Transport

• Definition: Movement of molecules with the concentration gradient, assisted by a carrier protein

• Types:

  • Channel Proteins

  • Carrier Proteins

• Examples:

  • Aquaporins

  • Glucose Transporters

Passive Transport

• Definition: Movement of molecules with the concentration gradient, not requiring energy

• Types:

  • Simple Diffusion

  • Osmosis

  • Facilitated Diffusion

• Examples:

  • Oxygen Diffusion

  • Water Diffusion

  • Ion Diffusion

Hydrostatic Pressure

• Force against capillary membranes during pumping.

• PUSHES fluid into ISF/ICF

Osmotic Pressure

• Na+ and Plasma protein (solute/particle) pressure

• PULLS fluid into IS/ICF

Oncotic Pressure (Colloidal Oncotic Pressure)

• The force exerted by albumin

Osmolarity vs. Osmolality

• Osmolarity: number of solute particles per 1 L of solvent

• Osmolality is the number of solute particles in 1 kg of solvent.

  • Na+ is the main determining solute

Tonicity

• Tonicity is the relative concentration of solutes dissolved in solution which determine the direction and extent of diffusion.

  • Isotonic

    • 0.9% NSS

    • Lactated Ringers

  • Hypotonic

    • 0.45% NSS

  • Hypertonic

    • 3%Saline

Fluid Homeostasis

Fluid homeostasis is maintained by:

• Habit

• Thirst

• RAAS

  • Aldosterone

  • ADH

• Natriuretic peptides

Intake ➔ Distribution ➔ Excretion

Fluid and Electrolyte Imbalances

Edema:

• Inflammation

• Dependent /Pitting

• Increased hydrostatic pressure

• Decreased Osmotic pressure

Sequestered fluids:

• "3rd Spacing"

• Effusions

Fluid Volume Excess:

• SIADH

• HF

Fluid Volume Deficit:

• Burns

• Illness

• Fever

• Blood loss

Electrolyte Imbalances

Intracellular /Extracellular Prevalence

• The prevalence of intracellular anions/cations/substances are those that start with "P".

Sodium (Na+) 135-145mEq/L

Hyponatremia

• Renal hypovolemia/hyponatremia (condition) = kidney problems

• Non-renal hypovolemia/hyponatremia

• Diarrhea

• Vomiting

• Burns

• Dilutional Hyponatremia (dilution)

Hypernatremia

• Usually due to dehydration (water loss) or renal impairment where there is no reabsorption of water or no ADH secretion

Dilutional Hyponatremia

• Also known as water intoxication, it is a potentially life­ threatening condition which occurs when a person consumes too much water without an adequate intake of electrolytes

Potassium (K+) 3.5 - 5.2mEq/L

Hypokalemia

Causes:

• Diuretics

• Poor PO intake

• ETOH

• Bariatric Surgery

Symptoms:

• Nausea/vomiting

• Cardiac arrhythmias

• Weakness/fatigue

Hyperkalemia

Causes:

• Usually caused by renal impairment

Symptoms:

• Early = numbness/tingling in extremities, muscle cramping, confusion

• Late = Bradycardia, irregular HR, arrest

• **Peaked T wave

Calcium (Ca+2) 8.7-10 mg/dL

Hypocalcemia

Causes:

Symptoms:

• Neuromuscular excitability

• Parasthesias

• Seizures

• Dementia

• Death

  • Trousseau's/Chvostek's

Hypercalcemia

Causes:

Symptoms:

• Flaccidity

• Constipation

• Decreased neuromuscular activity

Phosphorous (P04-) 2.5-4.Smg/dL

Hypophosphatemia

Causes:

• Decreased GI absorption

• Increased excretion by kidneys

• Intracellular shift (acid/base imbalance)

Symptoms:

• Tremors

• Parasthesia

• Weakness

Hyperphosphatemia

Causes:

• Renal Failure

Symptoms:

• Neuromuscular excitability

• Parasthesias

• Seizures

• Dementia

• Death

  • Trousseau's/Chvostek

Trousseau's Sign

• Hand spasm caused by inflating a blood pressure cuff

• Sign of hypocalcemia

• Can be observed in patients with tetany

• Can be a symptom of hypoparathyroidism

• Can be used to diagnose latent tetany

Chvostek's Sign

• Facial muscle twitching in response to tapping the facial nerve

• Sign of hypocalcemia

• Can be observed in patients with tetany

• Can be a symptom of hypoparathyroidism

• Can be used to diagnose latent tetany

Magnesium (Mg+2) 1.5-2.SmEq/dL

Hypomagnesemia

Causes:

• Usually in conjunction with hypokalemia

• Diarrhea

• Laxative abuse

• Sepsis/ETOH

Symptoms:

• Chvostek's

• Tetany

• Arrhythmias - Torsades de Pointes

Hypermagnesemia

Causes:

• Renal dysfunction/failure

Symptoms:

• Weakness

• Hypotension

• Arrythmias