Sodium imbalances

The body s normal daily sodium requirement is 1.0 to 1.5 mEq/kg (80 to 130 mEq, which is 80 to 130 mmol) to maintain a normal serum sodium concentration of 136 to 145 mEq/L (136 to 145 mmol/L).15 Sodium is the predominant cation of the ECF and largely determines ECF volume. Sodium is also the primary factor in establishing the osmotic pressure relationship between the ICF and ECF. All body fluids are in osmotic equilibrium and changes in serum sodium concentration are associated with shifts of water into and out of body fluid compartments. When sodium is added to the intravascular fluid compartment, fluid is pulled intravascularly from the interstitial fluid and the ICF until osmotic balance is restored. As such, a patient s measured sodium level should not be viewed as an index of sodium need because this parameter reflects the balance between total body sodium content and TBW. Disturbances in the sodium level most often represent disturbances of TBW. Sodium imbalances cannot be properly assessed without first assessing the body fluid status. 

Q71 In patients suffering from Addison s disease, lithium should be used with caution. Addison s disease is associated with sodium imbalance. 

The thiazides inhibit chloride ion reabsorption. Positive ions such as sodium and potassium also be exreted as counterbalancing ions. The sodium imbalance will also affect the bicarbonate ion excretion. All thiazides have similar potency at the maximum dosage. 

The primary electrolyte imbalance associated with the hypovolemia, a loss of sodium (i.e., hyponatremia), may require sodium infusions until the underlying condition has been resolved. Since electrolytes may shift in response to sodium imbalances, other replacements may be indicated (see Chapter 5). 

Identify patients at high risk for sodium imbalance. 

Distinguish symptoms of excess and deficient sodium levels. Identify diagnostic values associated with sodium imbalances. 

Determine the nursing implications related to treatments for sodium imbalances. 

Sodium also plays an important role in nerve impulse generation and transmission. As a part of the sodium-potassium pump, the difference between the potassium and sodium concentrations is maintained through active transport across the cell membrane as needed with the help of adenosine triphosphate (ATP) as an energy source. The flow of sodium and potassium across the cell membrane of electrically charged cells results in depolarization. Thus sodium is important for nerve and muscle function. As such, sodium imbalances can affect cardiac and respiratory muscle function as well as mobility. 

Nursing assessments that support the detection and care planning for patients with suspected sodium imbalance involve taking a history related to sodium intake, including... 

Sodium is the primary positive ion in extracellular fluid and is a major determinant of fluid concentration or extracellular osmolality. Sodium is present in the body in a variety of forms and is stored in the bones and, more prevalently, in body fluids. Sodium is important for blood pressure maintenance, nerve impulse conduction, and circulation of nutrients into the cell. Thus sodium imbalance (outside the 135-145 mEq/L range) can result in fluid imbalance, as well as other electrolyte imbalances. 

Sodium imbalances can lead to other electrolyte imbalances, and if not corrected quickly, potassium imbalance can be fatal because imbalances can lead to nerve and cardiac dysfunction. 

Overtreatment of sodium imbalance could result in the opposite, sodium imbalance, as well as fluid and electrolyte (potassium) imbalances, if care is not exercised. 

A 25-year-old patient admitted after a car accident with head injury begins to have massive urine output (500 mL/h). The nurse is concerned that the patient will soon demonstrate a sodium imbalance. The nurse would anticipate which of the following treatment to address the sodium imbalance the patient is at highest risk for ... 

Bailey McIntosh, age 34, was in a motocycle accident. His arterial blood gases show a pH of 7.30, and the nurse infuses four times the standard amount of sodium bicarbonate as ordered. The nurse also infuses a normal saline drip at a rate of 200 mL/h. The nurse would watch closely for which of the following signs of a likely sodium imbalance ... 

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