Patho nsg 533- MODULE 2: Fluid, Electrolyte Disorders

Patho nsg 533- MODULE 2: Fluid, Electrolyte Disorders The total amount of ______ in the body is responsible for the extracellular fluid ______. The total amount of sodium in the body is responsible for the extracellular fluid volume. The total amount of ______ in the body is responsible for the extracellular ______ concentration. The total amount of water in the body is responsible for the extracellular sodium concentration. Extracellular fluid volume and extracellular sodium concentration- can you change one and not the other? Extracellular fluid volume and extracellular sodium concentration are independent factors. You can change one without influencing the other. For example, you can have a patient who is normovolemic (euvolemic) but can be either hyponatremic, hypernatremic, or eunatremic--or you can have a patient who is eunatremic who is either hypervolemic, hypovolemic, or euvolemic. What three main systems regulate total body sodium and therefore the size of the extracellular fluid compartment? Three main systems regulate total body sodium and therefore the size of the extracellular fluid compartment: Decreased renal perfusion, Volume receptors in the great veins are sensitive to small changes in venous and atrial filling. Increased atrial filling stimulates volume receptors and results in release of atrial natriuretic factor/peptide (ANF/ANP) and brain natriuretic factor/peptide (BNF/BNP) which promote sodium excretion. Pressure receptors in the aorta and carotid sinus are stimulated by volume depletion and subsequently active the sympathetic nervous system, leading to renal retention of sodium. The kidney adjusts sodium excretion through what hormone? The kidney normally adjusts sodium excretion with the use of aldosterone to keep extracellular fluid volume within the acceptable range. The kidney adjusts water excretion with what horomone? The kidney also adjusts water excretion (through Antidiuretic Hormone or ADH) to keep extracellular sodium concentration within its normal range. ADH secretion is initiated by a change in ________ or a decrease in _________. ADH secretion is initiated by a change in plasma osmolality or a decrease in circulating blood volume/blood pressure. How is osmolality calculated? OSM (calc) = 2 X [sodium concentration] + [glucose concentration/18] + [BUN/2.8] Osmolality is determined by ____________ Osmolality is determined by the total solute concentration in a fluid compartment. Tonicity refers to the ability _________. Tonicity refers to the ability of the combined effect of all the solutes to generate an osmotic driving force that causes water movement from one compartment to another. Solutes capable of changing the tonicity (i.e., translocating water from one body fluid compartment to another) are: (4 of them) Solutes capable of changing the tonicity (i.e., translocating water from one body fluid compartment to another) are: sodium, glucose, mannitol, and sorbitol sodium, glucose, mannitol, and sorbitol are called what? sodium, glucose, mannitol, and sorbitol are called effective osmoles What is a ineffective osmole? Urea contributes to the osmolality, but it easily crosses cell membranes and distributes evenly throughout total body fluids = ineffective osmole. normal body fluid osmolality is ??? - ??? mOsm/Kg (milliosmoles per kilogram) normal body fluid osmolality is 280-294 mOsm/Kg (milliosmoles per kilogram) Volume depletion or volume excess with a normal osmolality, are considered __________ alterations Volume depletion or volume excess with a normal osmolality, are considered isotonic alterations (isotonic hypovolemia or isotonic hypervolemia). Volume depletion or volume excess with an increased osmolality, are considered _____________ alterations. These patients are usually _____________ Volume depletion or volume excess with an increased osmolality, are considered hypertonic alterations. (hypertonic hypovolemia or hypertonic hypervolemia). The increase in osmolality may be related to an increase in sodium, but usually the cause is the loss of free water or failure to replace water loss. These patients are usually hypernatremic. The water deficit is ________________. The water deficit is the difference between ideal total body water (TBW) and current total body water how do you calculate total body water? Current TBW = weight in kg x (0.4 for women) (0.5 for men) (0.6 for infants) how do you calculate ideal total body water? Ideal TBW = (Na (current) X TBW)/140 NOTE: Ideal Sodium is 140mEq/L how do you calculate water deficit