Electrolyte & Fluid Balance

Patho

Blood pH

7.35-7.45

- 7.4 is ideal

• less than 7.4 is considered acidic, more than 7.4 considered alkaloid

pCO2

35-45 mmHg

PO2

• 80-100 mmHg

O2 saturation

• 95-100%

HCO3-

22-26 mEq/L

Metabolic Acidosis:

• Identified when the pH and bicarbonate are both low

This can happen for 2 Reasons:

1. Loss of bicarbonate (which is a base) due to diarrhea / diuretics

• “Below the waist, bye base!”

• This leaves patient without enough base to balance out the acid, and acidosis occurs

2. An excessive accumulation of acid from either lactic acidosis, diabetic ketoacidosis, kidney failure, or starvation. 

• This patient could have a headache, confusion, and increased respiratory rate and depth to compensate 

• Patient could go into shock if their pH drops below 7 

Metabolic Alkalosis:

• Occurs when the pH and bicarbonate are both high

This can be caused by:

• Loss of potassium or vomiting 

• “Above the waist, adios acid!”

Clinical Manifestations:

• Hypocalcemia symptoms such as Trousseau and Chvostek signs 

• Slow respiratory rate to compensate 

• Kidneys trying to excrete more bicarbonate if able 

Treatment:

• Correct underlying cause 

• IV fluids

• Potassium for hypokalemia 

Respiratory Acidosis:

• Occurs from LOW pH and HIGH CO2, caused by inadequate excretion of it 

The body retains CO2, which can happen due to pulmonary issues, hypoventilation, or an overdose of sedatives.

Manifestations:

• Changes in mental status 

• Hyperkalemia 

If more of a chronic process due to lung condition, the patient may be asymptomatic. 

Treatment:

• Reversal of sedative medications  

• Intubation 

• BiPAP (bilevel positive airway pressure)

• Hydration 

Respiratory Alkalosis:

• Occurs with a HIGH pH and a LOW CO2 

Caused by:

• Hyperventilation from a process such as anxiety

• Hypoxemia 

• Early sepsis 

• Labor 

• Hepatic insufficiency 

• Cerebral tumors 

Clinical Manifestations:

• Patient may feel lightheaded 

• Have a change in mental status 

• Tachycardia 

• Arrhythmias 

Treatment:

• Rebreathe exhaled CO2 (people breathe into paper bags)

RAAS:

• Initiated by decreased perfusion to the kidneys 

• The kidneys release renin 

• Renin combines with angiotensinogen to form angiotensin I

• Angiotensin I is converted in the lungs to Angiotensin II

• Angiotensin II stimulates the adrenal cortex to release aldosterone

• Aldosterone directs the kidney to reabsorb more sodium 

• Water follows sodium back into ECF

ADH

• Secreted by posterior pituitary gland

• Released in response to increased osmolality 

• Increases water retention

Hypovolemia (fluid volume deficit), is diminished blood volume

Conditions that can result in Hypovolemia:

• Fluid loss (most common cause)

• Hemorrhage 

• Frequent urination 

• Vomiting 

• Diarrhea 

• Fistulas 

• Fever

• Excessive nasogastric suctioning 

Clinical Manifestations & Treatment of Hypovolemia

Clinical Manifestations:

• Hypotension / Tachycardia 

• Thirst / Poor skin turgor 

• Dry mucous membrane / Decrease urinary output  / Flattened neck veins 

If severe, there will be a decreased preload to the heart, which causes a decrease in cardiac output, resulting in hypovolemic shock. 

Treatment:

• Oral or Parenteral fluids 

• Blood or blood products, if due to hemorrhage 

• Antidiarrheals if the loss is from diarrhea 

• Antiemetics if loss is from vomiting 

• Vasopressors may be orders, if patient is in hypovolemic shock 

Hypervolemia: Fluid Volume Excess

• Abnormally increased volume of blood

• Causes: Increase in sodium and water retention, excessive increase in sodium & water intake or, fluid shifting from intracellular space into extracellular space 

Selected Causes of Hypervolemia:

• Renal failure

• Heart failure 

• Cirrhosis 

• Nephrotic syndrome 

Clinical Manifestations & Treatment of Hypervolemia

Clinical Manifestations of Hypervolemia:

• Dyspnea / Crackles / Tachypnea 

• Bounding, rapid pulse 

• Hypertension / Distended neck veins /

• Edema / Ventricular gallop  / Clammy skin 

Treatment:

• Identify and treat the underlying cause 

• Restrict sodium and water fluid intake 

• If severe, the oxygen therapy, morphine, intravenous diuretics, and mechanical ventilation 

Edema:

• An accumulation of an excessive amount of watery fluid in cells or intracellular tissues 

• Excessive accumulation of fluid in the interstitial space

May be: Localized (trauma/inflammation)  / Generalized (whole body) 

Third Spacing:

• Loss of extracellular fluid from the vascular to other body components

Sometimes extracellular fluid becomes trapped in a space where it’s unable to be utilized or excreted, which is called third spacing.

Types

• Ascites: Accumulation of serous fluid in the peritoneal cavity 

• Pleural effusion: Increased fluid in the pleural space, can cause shortness of breath by compression of the lung and/or increased intrathoracic pressure resulting in mediastinal shift and increased work of breathing.

Hyponatremia:

• Deficit of sodium (serum sodium level < 135mEq/L)

• Causes water to shift out of the extracellular spaces and into the cells

Causes of Hyponatremia:

Loss of sodium due to:

- Excessive diuresis 

• Diuretic therapy 

• Sodium-losing nephritis 

- Excessive sweating, with nonsodium fluid replacement 

- GI fluid loss 

• Vomiting / Diarrhea / Fistulas 

- Adrenocorticoid insufficiency 

Excess of water due to:

• Excess oral fluids 

• Excess parenteral administration of dextrose and water solutions such as D5W

• Syndrome of inappropriate Antidieuretic Hormone (SIADH)

• Excessive IV administration 

Other: Psychogenic polydipsia, Excessive administration of 5% dextrose water, frequent tap water enemas, sweating & drinking water

Hyponatremia

Manifestations:

Are due to water shifting into cells, especially brain cells.

• Anorexia, nausea, vomiting 

• Muscle cramps / Depression / Lethargy 

• Weakness / Disorientation / Seizures

• Orthostatic hypotension / agitation 

* Apprehension / Headache / Personality Changes / Coma  

Treatment:

• Identify and treat cause 

• Restrict fluid intake (until normal sodium levels are reached)

• Administer hypertonic 3% sodium chloride solution slowly with caution, and only in clinical areas where close monitoring can be maintained 

Hypernatremia: 

• Excess of sodium (serum sodium level > 145 mEq/L)

• Causes water to shift out of the cell into the extracellular fluid 

Causes of Hypernatremia:

Intake of excessive sodium due to:

• Rapid infusion of hypertonic saline, sodium bicarbonate, or isotonic saline 

• Drinking salt water

• Ingesting large amounts of salt without increasing water intake 

Loss of water due to:

• Diarrhea / Diabetes insipidus 

• Increase in insensible loss / Decreased water intake 

• Unavailability of water / withholding water 

• Impaired thirst center 

Other: Rapid infusion of 3% NaCl, Unconscious state, hypertonic tube feedings, trauma to thirst center

Hypernatremia: 

Manifestations:

Are due to intracellular dehydration and intravascular volume depletion.

• Thirst / Weak, rapid pulse / Irritability 

• Dry, sticky mucous membrane 

• Decreased blood pressure 

• Oliguria or anuria 

• Decreased reflexes / disorientation 

• Hallucinations 

Treatment:

• Administer hypotonic solution, such as 0.45 NaCl or 3% NaCl

• Too rapid a shift can cause cerebral edema

• If diabetes insipidus is the cause of hypernatremia, desmopressin or vasopressin may be ordered

Hypokalemia: 

• Serum potassium level < 3.5 mEq/L

Other causes:

• Alcoholism 

• Alkalosis 

• Anorexia nervosa 

• Cushing syndrome 

• Diuretic agents 

• Hyperalimentation 

• Prolonged vomiting/diarrhea 

Causes: metabolic alkalosis, loop diuretics, excessive steroid therapy, anorexia nervosa 

Manifestations:

Are due to alterations in cardiovascular, skeletal, and gastrointestinal function;

Causes:

• Apnea 

• Hypotonic bowel sounds 

• Muscle fatigue 

• Digitalis toxicity 

ECG changes with hypokalemia:

• Flattened T waves

• Prolonged PR interval 

• Large U wave 

Patient Care:

• Identify underlying cause and treat it

• Replacement therapy, either P.O or IV depending on severity

Foods High in Potassium:

• Oranges / Bananas / Canteloupes / Prunes / Squash / Raisins / Dried Beans / Potatoes / Sweet Potatoes 

Administer IV potassium with an IV pump

Check policy regarding rate of infusion 

Hyperkalemia:

• Serum potassium level > 5.0 mEq/L 

Other Causes:

• Acidosis (H+ into cell so K+ out of cell)

• Burns 

• Crushing injuries 

• Hypoaldosteronism (primary adrenal insufficiency)

• Rapid IV administration 

• Renal failure 

Causes:

Rapid infusion of KCl, third-degree burn, anuria, acidosis

Manifestations of Hyperkalemia:

Are related to potassium’s influence on resting membrane potentials 

Causes:

• Abdominal pain

• Tingling fingers 

ECG changes with hyperkalemia:

• Tall peaked T waves 

• Widening QRS complex

• Ventricular fibrillation 

• Cardiac arrest  

Patient Care:

• Reduce intake of foods high in potassium 

• Stop potassium-sparing diuretics 

• Give kayexalate (sodium polystyrene sulfonate)

• Administer 50% glucose with insulin IV

Hypochloremia:

• Serum chloride level < 95 mEq/L

Causes of Hypochloremia:

Loss of hydrochloric acid from:

• Excessive vomiting 

• GI suctioning 

Clinical Manifestations:

• Metabolic alkalosis 

• Hypertonicity of muscles 

• Depressed respiration 

• If severe, tetany 

Patient Care:

• Identify and treat the cause 

• Replacement therapy

Hyperchloremia:

• Serum chloride level > 105 mEq/L

Causes of hyperchloremia:

• Excessive ingestion 

• Decreased excretion by kidney 

Clinical Manifestations:

• Metabolic acidosis 

• Stupor 

• Deep, rapid respirations 

• Weakness 

• If severe, coma 

Patient Care:

• Treat metabolic acidosis 

• Sodium bicarbonate IV

• Lactated Ringer’s solution

Hypophosphatemia:

• Serum phosphate levels < 2.5 mg/dL

Causes of Hypophosphatemia

• Alkalosis 

• Diabetic ketoacidosis 

• Hyperalimentation 

• Hyperparathyroidism 

• Phosphate-binding antacids (aluminum & calcium)

Clinical Manifestations:

• Hemolysis 

• Platelet dysfunction 

• Parasthesia 

• Seizure 

Treatment:

• Identify and treat the underlying causes 

• Replacement therapy either PO or I, depending on severity

Hyperphosphatemia: 

• Serum phosphate level > 4.5 mg/dL

Causes of Hyperphosphatemia

• Renal failure

• Hypoparathyroidism 

• Chemotherapy 

• Large intake of calcium 

• Excessive use of phosphate laxatives or enemas 

Clinical Manifestations:

• Tetany 

• Hypotension 

• ECG with shortened QT interval 

Treatment:

• Identify and treat underlying causes 

• Restrict intake 

• Calcium-based phosphate binders

Hypomagnesemia:

• Serum magnesium level: < 1.5 mg/dL

Selected Causes of Hypomagnesemia:

• Diuretic therapy 

• SIADH

• Small bowel bypass surgery 

• Hypercalcemia 

• Malnutrition 

• Diuretic therapy 

• Diabetic ketoacidosis 

Treatment: replacement therapy

Hypermagnesemia:

• Serum magnesium level: > 2.5 mg/dL

Selected Causes of Hypermagnesemia: 

• Decrease in renal excretion

• Increase in intake (antacids, enemas, lax)

• Traumatic soft tissue injury 

ECG Changes:

• Ventricular extrasystole 

• Prolonged PR interval 

• Widening of QRS complex 

• Tall T wave 

• Complete heart block 

• Cardiac arrest

• Hypovolemic shock / tissue trauma / renal failure 

Treatment:

• Eliminate ingestion

• Calcium

Sodium:

• Normal serum rate = 135-145 mEq/L

Potassium:

Normal serum range is 3.5-5.0 mEq/L

Chloride

• Normal serum range = 95-105 mEq/L

Calcium

• Normal serum range = 8.5 - 10.5 mg/dL

Phosphorus

• Normal serum range = 2.5 - 4.5 mg/dL

Magnesium

• Normal serum range: 1.5 - 2.5 mg/dL

Hypocalcemia:

• Serum calcium level < 8.6 mg/dL

Causes of Hypocalcemia:

• Hypoparathyroidism

        - surgical removal 

        - idiopathic 

       - thyroid cancers 

• Hyperphosphatemia 

• Malabsorption 

• Vitamin D deficiency 

• Excessive administration of citrated blood

• Hypoalbuminemia 

Clinical Manifestations:

• Numbness, tingling of hands/toes/ around mouth 

• Weakness/Muscle cramping /Hypotension 

• Emotional instability 

• Hyperactive deep tendon reflexes 

• Chvostek sign (unilateral spasm)

• Trousseau sign 

• Tetany / Seizures / Poor clotting 

• Decreased myocardial contractility 

• EKG with shortened GI interval 

Treatment:

• Oral replacement

    - dietary supplement of calcium with vitamin D 

• IV calcium replacement 

    - calcium gluconate

    - calcium chloride

Hypercalcemia:

• Serum calcium level > 10.5 mg/dL 

Selected causes for Hypercalcemia:

• Hypophosphatemia 

• Certain cancers 

• Thyrotoxicosis 

• Acromegaly 

• Renal failure 

Clinical Manifestations:

• Anorexia, nausea, and vomiting 

• Constipation 

• Hypertonicity of the muscles 

• Increase in cardiac contractility 

• Decrease in heart rate 

• Renal calculus 

• EKG with wide T wave 

• Confusion 

Treatment:

• Identify and remove the cause, if possible 

• IV fluids with diuretic