Fluid And Electrolyte Flashcards
Intracellular and Extracellular Fluid
2/3 is intracellular 1/3 is extracellular
Intracellular = potassium, magnesium (small amounts of sodium, chloride, bicarbonate, phosphate)
Extracellular = sodium and chloride (small amounts of bicarbonate, phosphate, calcium, magnesium, and potassium)
ICF and ECF always have equal amounts of cations and anions
Edema: mechanisms of formation
I. Increase in capillary filtration pressure
Increased vascular volume - HF, kidney disease, IV overload
Venous obstruction - thrombophlebitis
Liver disease - portal vein obstruction
Acute pulmonary edema
Dependent edema
- Decrease in capillary colloidal osmotic pressure
Increased loss of plasma proteins - burns, kidney disease
Decreased production of plasma proteins - liver disease, malnutrition
General edema - Increase in capillary permeability
Inflammation, allergic reactions, malignancy, ascites, pleural effusion, tissue injury, burns
Localized non pitting - Produce an obstruction of lymph flow
Malignant obstruction, surgery
Localized to area of impaired drainage
Edema: manifestations
Edema to brain, larynx, lungs, pericardial, pleural, peritoneum = life threatening
Joint spaces, coccyx, ankles, feet = discomfort, impaired rom
Tourniquet - blood vessel compression
Pressure ulcers - further for nutrients to diffuse
Psychological self concept
Non pitting edema = proteins accumulated in tissues and coagulated
Edema: Treatment
elevation - counter gravity
Diuretic therapy - decrease fluid volume
Massage - promote lymphatic and vascular return
ROM - lymphatic and venous return
Serum albumin - given to IV to raise colloid plasma oncotic
Elastic support stockings - oppose fluid movement
Third Space Accumulations
Loss or movement and trapping of ECF in trans compartment all spaces (serous, pericardial, peritoneal, pleural)
Cavities are often closely linked with lymphatic drainage
Milking action of moving structures (lungs) moves fluid and proteins back into lymphatic channels
Gain in body weight doesn’t contribute to fluid reserve or function
Hydrothorax - edema in the pleural cavity
Ascites - fluid in peritoneal cavity due to liver failure
Effusion - transmutation of fluid into serous cavities
Water gain and water loss
Positive water balance = decreased osmolality and sodium
Negative water balance = increased osmolality and sodium
Gain - intake, metabolic processes
Loss - kidney, skin (insensible loss), lungs (insensible loss), GI
Water Regulation
Aldosterone - increased sodium reabsorption and potassium excretion = increased blood volume
Renin, stress, trauma,
ADH - increases sodium reabsorption, aquaporins = increased blood volume
ECF volume and osmolality
Renin - angiotensin II = increased aldosterone, and sodium reabsorption = increased blood volume
Blood pressure low
Thirst and ADH regulate water intake and output
Sodium Regulation
Sympathetic Nervous System: changes in arterial blood pressure = adjust in GFR and sodium reabsorption
RAAS - increase sodium reabsorption and vasoconstriction
Thirst control
High osmolality = thirst and ADH release
Low osmolality = lack of thirst and decreased ADH release
Cellular dehydration (osmolality) and decrease in circulating volume (stretch receptors) stimulates hypothalamus to thirst and production of angiotensin II (nonosmotic thirst; back up)
Hypodipsia and Polydipsia
Decreased ability to sense thirst
Commonly associated with lesions in the area of the hypothalamus (trauma, hemorrhage, meningiomas)
Excessive thirst
Inappropriate or false thirst - despite normal body water; CHF, chronic kidney disease
Compulsive water drinking - schizophrenia, smoking
Diabetes Insipidus: Causes
Deficiency in ADH or a decreased renal response to ADH
Expelling large amounts of urine and excessive thirst
Danger arises when pt is unable to communicate need for water or unable to secure water
Neurogenic DI - deficit in synthesis or release of ADH
Inflammatory, autoimmune, vascular disease
Many have an incomplete form
Nephrotic DI - kidneys do not response to ADH
Congenital, pyelonephritis, lithium toxicity, electrolyte disorders
Diabetes Insipidus: Manifestations
Intense thirst Craving ice water Polyuria Reduced fluid volume Polydipsia Hypernatremia Dehydration
Syndrome of Inappropriate Antidiuretic Hormone: Causes
Failure of negative feedback system regulating ADH leading to water retention
Dilutional hyponatremia
Surgery, pain, stress, temperature changes, drugs, lung tumours, chest lesions, CNS disorders,
Tumors
Intrathoracic conditions - TB, pneumonia, positive pressure breathing
SIADH: manifestations
Dilutional hyponatremia
Decreased urine output
Urine osmolality high
Hematocrit, serum sodium, BUN, decreased
Isotonic Fluid Volume Deficit: Causes
Water and electrolytes lost in isotonic proportions
Severe vomiting Diarrhea GI suction Excess urinary loss Excess sweating Endocrine disorders - adrenal insufficiency 3rd space losses
Isotonic Fluid Volume Deficit: Manifestations
Decreased body weight Thirst Oliguria Urine gravity increases Eyes look sunken Tissue turgor decreases BP decrease, HR increase, weak pulses Postural hypotension
Hypovolemic shock
Vascular collapse
Isotonic Fluid Volume Deficit: Treatment
Fluid replacement and measures to correct underlying cause
Isotonic Fluid Volume Excess: Causes
Isotonic expansion of ECF - increase in total body sodium and body water
Excess intake of sodium
Heart failure - compensatory increase
Liver failure - impaired aldosterone metabolism
Corticosteroid hormone excess - increased reabsorption of sodium
Circulatory overload
Isotonic Fluid Volume Excess: Manifestations
Weight gain Dependent edema Distended neck veins Slow emptying peripheral veins Full bounding pulse Increased central venous pressures Fluid accumulation in lungs - SOB, dyspnea, crackles, productive cough
Ascites
Pleural effusion
Isotonic Fluid Volume Excess: Treatment
Sodium restricted diet
Diuretics
Hyponatremia: Causes
Serum sodium below 135
Most common disorder
Hypertonic hyponatremia - hyperglycemia
Hypovolemic hypotonic hyponatremia - excessive sweating, GI fluid loss, adrenal insufficiency
Euvolemic hypotonic hyponatremia - SIADH
Hypervolemic hypotonic hyponatremia - HF, liver disease, renal failure, MDMA abuse
