Body Fluids and Electrolyte

Body Fluids and electrolyte:

Definitions:  

·         Intracellular: Fluid within the cell

·         Extracellular: Fluid outside the cell but in the interstitial space and in intravascular fluid

·         Interstitial: Fluid between the cells; in the interspaces of a tissue, situated between the parts

·         Intravascular: Within the vessel or vessels

·         Homeostasis: The tendency of biological systems to maintain relatively constant conditions in the interval environment, while continuously interacting with and adjusting to changes that originate within the system and outside the system                   

Transport of Fluids

·         Diffusion: The movement of molecules/solutes through a semi-permeable membrane from a high concentration of particles to a low concentration

·     Osmosis: The one way passage of water through a semi-permeable membrane from a low    concentration of particle to a high concentration of particles

·         Filtration: Fluid going through a filter under pressure or passage through a material that prevents passage of certain molecules

·         Active transport: Electrolytes moves from a low concentration to a high concentration by moving against the concentration gradient. ATP provides the energy needed to do this.   

IV therapy

As many as 75% of patients admitted into hospital receive some types of IV therapy

50%-70% of the average human is body fluids

Distribution of fluid in the body is:

1/3 extracellular fluid

·         Interstitial fluid

·         Plasma or intravascular fluid

·         Transcellular fluid

2/3 intracellular fluid

·         Fluid within a cell

·         Red blood cells

·         Others cells

Uses of IV therapy

·         Establish or maintain fluid and/or electrolyte balance

·         Administer medication continuously or intermittently

·         Administer fluid to maintain venous access in case of an emergency

·         Administer blood or blood products

·         Administer intravenous anaesthetics

·         Maintain or correct a patient’s nutritional status

·         Administer diagnostic reagents

·         Monitor haemodynamic functions

·         Correct acidosis or alkalosis

Types of IV fluids

1.      Crystalloids

2.      Colloids

3.      Blood and blood products

1. Crystalloids

·         Crystalloids are water with electrolytes that form a solution that can pass through semi-permeable membranes

·         They are lost rapidly from the intravascular space into the interstitial space

·         They can remain in the extracellular compartment for about 45 minutes

·         Because of this, larger volumes than colloids are required for fluid resuscitation

·         Eventually, water from crystalloids diffuses through the intercellular fluid.

Hypertonic:

A hypertonic solution draws fluid into the intravascular compartment from the cells and the interstitial compartments. Osmolarity is higher than serum osmolarity.

Hypotonic:

A hypotonic solution shifts fluid out of the intravascular compartment, hydrating the cells and the interstitial compartments. Osmolarity is lower than serum osmolarity.

Isotonic:

Because an isotonic solution stays in the intravascular space, it expands the intravascular compartment. Osmolarity is the same as serum osmolarity.

Some common examples of crystalloids:

1. Dextrose 5% in water (D5W):

Type: Isotonic

Uses:

·         Fluid loss

·         Dehydration

·         Hypernatraemia

Nursing considerations:

·         Use cautiously in renal and cardiac patients.

·         Can cause fluid overload.

·         May cause hyperglycaemia or osmotic dieresis.

2. 0.9% Sodium Chloride (Normal Saline-NaCl):

Type: Isotonic

Uses:

·         Shock

·         Hypernatraemia

·         Blood transfusions

·         Resuscitation

·         Fluid challenges

·         Diabetic Keto Acidosis(DKA)

Nursing Considerations:

·         Can lead to overload

·         Use with caution in patients with heart failure or edema

·         Can cause hyponatraemia, hypernatraemia, hyperchloraemia or calorie depletion.

3. Lactated Ringer’s (Hartmanns)

Type: Isotonic

Uses:

·         Dehydration

·         Burns

·         Lower GI fluid loss

·         Acute blood loss

·         Hypovolaemia due to third spacing

Nursing considerations:

·         Contains potassium, don’t use with renal failure patients

·         Don’t use with liver disease, can’t metabolise lactate.

4. 0.45% Sodium Chloride (1/2 Normal Saline)

Type: Hypotonic

Uses:

·         Water replacement

·         DKA

·         Gastric fluid loss from NG or vomiting.

Nursing considerations:

·         Use with caution

·         May cause cardiovascular collapse or increased intracranial pressure

·         Don’t use with liver disease, trauma or burns.

5. Dextrose 5% in ½ normal saline

Type: Hypertonic

Uses: Later in DKA

Nursing considerations:

·         Use only when blood sugar falls below 250mg/dl

6. Dextrose 5% in normal saline

Type: Hypertonic

Uses:

·         Temporary treatment from shock if plasma expanders aren’t available

·         Addison’s crisis

Nursing considerations: Contra-indicated for cardiac or renal patients

7. Dextrose 10% in water

Type: Hypertonic

Uses:

·         Water replacement

·         Conditions where some nutrition with glucose is required.

Nursing consideration: Monitor blood sugar levels

2. Colloids:

·         Colloids contain solutes in the form of large proteins or other similar sized molecules.

·         They cannot pass through the walls of capillaries and into cells.

·         They remain in blood vessels longer and increase intravascular volume.

·         They attract water from the cells into the blood vessels.

·         But this is a short term benefit and

·         Prolonged movement can causes the cells to lose too much water and become dehydrated.

Some common examples of colloids:

1. Albumin (Plasma protein) 4% or 20%

Action/Use:

·         Keeps fluids in vessels

·         Maintain volume

·         Primarily used to replace protein and treat shock

Nursing considerations:

·         May cause anaphylaxis (a severe, often rapidly progressive allergic reaction that is potentially life threatening)- watch for/report wheeze, persistent cough, difficulty breathing/talking, throat tightness, swelling of the lips, eyes, tongue, face, loss of consciousness.

·         May cause fluid overload and pulmonary edema.

2. Dextran (polysaccharide) 40 or 70

Action/Uses:

·         Shifts fluids into vessels

·         Vascular expansion

·         Prolongs hemodynamic

·         Response when given with HES

Nursing considerations:

·         May cause fluid overload and hypersensitivity

·         Increased risk of bleeding

·         Contraindicated in bleeding disorders, chronic heart failure and renal failure

3. Hetastarch (HES) 6% or 10%

Action/use:

·         Shifts fluids into vessels

·         Vascular expansion

Nursing considerations:

·         May cause fluid overload and hypersensitivity

·         Increased risk of bleeding

·         Contraindicated in bleeding disorders, chronic heart failure and renal failure

4. Mannitol (alcohol sugar) 5% or 10%

Action/use:

·         Oliguric dieresis

·         Reduces cerebral edema

·         Eliminates toxins

Nursing considerations:

·         May cause fluid overload

·         May cause electrolyte imbalances

·         Cellular dehydration

·         Extravasation may cause necrosis

3. Blood and Blood Products:

a) Plasma: Plasma is the liquid part of the blood. It is often used to add volume to the blood system after a large loss of blood. Cryoprecipitate is a concentrated source of certain plasma proteins and is used to treat some bleeding problems.

b) Red blood cells: RBCs carry oxygen from lungs to other part of body and then carry carbon dioxide back to the lungs. Severe blood loss, either acute hemorrhagic or chronic blood loss, dietary deficit or erythropoetic issue of the bone marrow can result in a low red blood cell count- called anemia. A transfusion of whole blood or packed red blood cells may be needed to treat acute blood loss or anemia.

c) White blood cells: WBCs help fight infection, bacteria and other substances that enter the body. When the white blood cell count becomes too low, it is called Neutropenia. G-CSF injections may be needed to treat Neutropenia.

d) Platelets: Platelets help blood to clot. Platelet transfusions are given when the platelet count is below normal.

Complications of IV Therapy:

·         Local complications at the site including:

           -Extravasation

           -Phlebitis/Thrombophlebitis

           -Haematoma

           -infection

·         Fluid overload- Acute Pulmonary Oedema

·         Electrolyte imbalance- Cardiac arrthythmias

·         Transfusion reactions- Anaphylaxis

·         Air embolus

Electrolytes:

Electrolytes are minerals in the body fluids that carry an electric charge.

Electrolytes affect the amount of water, the acidity of blood (pH), muscle function, and other important processes in the body.

There are six major electrolytes:

·         Sodium- Na⁺ Major cation in extracellular fluid (ECF)

·         Potassium- K⁺ Major cation in intracellular fluid (ICF)

·         Calcium- Ca⁺⁺ Major cation found in ECF and teeth and bones

·         Phosphate- PO₄^3-  Major anion found in ICF

·         Magnesium- Mg⁺⁺ Major cation found in ICF (closely related to Ca⁺⁺ and PO₄)

Sodium (Na⁺)

Normal serum level 135-145 mmol/L

Function:

·         Maintain extracellular function (ECF) osmolarity

·         Influences water distribution

·         Affects concentration, excretion and absorption of potassium and chloride

·         Helps regulate acid-base balance

·         Aids nerve muscle fiber impulse transmission

Signs and symptoms of imbalance:

Hponatraemia:                                               Hypernatraemia:

Fatigue                                                            Thirst

Muscle weakness                                            Fever

Muscle twitching                                            Flushed skin

Decreased skin turgor                                     Oliguria

Headache                                                        Disorientation

Tremor, Seizures                                            Dry sticky membranes

Potassium:

Function:

·         Maintains cell electro-neutrality

·         Maintains cell osmolarity

·         Assists in conduction of nerve impulses

·         Directly affects cardiac muscle contraction (repolarisation in the action potential)

·         Plays a major role in acid-base balance

·         Sodium-potassium gradient plays a major role in fluid balance between ECF and ICF compartments.

Signs and symptoms of imbalance:

Hypokalaemia:                                      

Decreased peristalsis, skeletal muscle and cardiac muscle function

Muscle weakness or cramps

Decreased reflexes

Fatigue

Rapid, weak irregular pulse

Cardiac arrhythmias/cardiac arrest

Decreased blood pressure

Decrease bowel motility

Paralytic ileus

          Hyperkalaemia:

Muscle weakness

Nausea

Diarrhoea

Oliguria

Paraesthesia (altered sensation) of the face, tongue, hand and feet

Cardiac arrhythmias

Calcium (Ca⁺⁺)

Normal serum level 2.15-2.55 mmol/L

Function:

·         Enhances bone strength and durability

·         Helps maintain cell-membrane structure, function and permeability

·         Affects activation, excitation and contraction of sino-atrial node (intrinsic cardiac pacemaker), Cardiac and skeletal muscles

·         Participates in neurotransmitter release at synapses

·         Helps activate specific steps in blood coagulation

·         Activates serum complement in immune system function

Signs and symptoms of imbalance:

Hypocalcaemia:                                                 Hypercalcaemia:

Muscle tremor                                                      Lethargy

Muscle cramps                                                     Fatigue

Tetany                                                                  Depression

Tonic-clonic seizures                                          Confusion

Parasthesia                                                           Headache

Bleeding                                                              Muscle flaccidty

Arrhymias                                                           Nausea, vomitting

Hypotension                                                        Hypertension

Numbness or tingling in finger                           Anorexia

Chloride (Cl^-):

Normal serum levels 95-110 mmol/L

Function:

·         Maintain serum osmolarity

·         Combine with major cations to create important compounds, such as sodium chloride (NaCl), HCl, CaCl₂ which contribute to acid-base and /or electrolyte balance

Signs and symptoms of imbalance:

Hyperchloraemia:                                                     Hperchloraemia:

Increased muscle excitability                                   Headache, difficulty concentrating

Tetany                                                                       Drowsiness, stupor

Decreased respirations                                              Rapid, deep breathing

Phosphate (PO₄)

Normal serum Level 0.8-1.5 mmol/L

Function:

·         Helps to maintain bones and teeth

·         Helps to maintain cell integrity

·         Plays a major role in acid-base balance (as a urinary buffer)

·         Promotes energy transfer to cells

·         Plays essential role in muscle, RBCs and neurological function

Magnesium (Mg⁺⁺)

Normal Serum Level 0.70-1.05 mol/L

Function:

·         Activates intracellular enzymes, active in carbohydrate and protein metabolism

·         Acts on myo-neural vasodilation

·         Facilitates Na⁺ and K⁺ movement across all membranes

·         Influences Ca⁺⁺ levels

Signs and symptoms of imbalance:

Hypomagnesaemia:               Hypermagnesaemia:

Dizziness                                                            Drowsiness

Confusion                                                           Lethargy

Seizures                                                              Coma

Tremor                                                                Arrhythmias

Leg and foot cramps                                           Vague neuromuscular changes

Hyperirritability                                                  Nausea

Arrhythmias                                                        Slow, weak pulse

By: Ashish Acharya

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