dehydration in the elderly
Introduction
Introduction to dehydration in the elderly The loss of body fluid exceeds the intake of liquid, and the clinical manifestation is a decrease in the amount of extracellular fluid, that is, a low-capacity state in which the body fluid capacity is insufficient. Loss of water accompanied by sodium loss, the degree of loss can be different, the ratio of water and sodium loss is the same, the extracellular fluid osmotic pressure is maintained within the normal range, said isotonic water loss; water loss > sodium loss, extracellular fluid penetration Pressure>320mmol/L, blood sodium>150mmol/L, called hypertonic dehydration; loss of sodium> water loss, extracellular fluid osmotic pressure <280mmol/L, blood sodium <130mmol/L, called hypotonic dehydration, according to The amount of body fluid loss, dehydration is divided into three degrees, the water loss accounts for 3% to 6% of body weight for moderate dehydration, and the water loss accounts for more than 6% of body weight for severe dehydration. basic knowledge The proportion of sickness: 0.01% Susceptible people: the elderly Mode of infection: non-infectious Complications: neurosis fainting coma shock
Cause
Dehydration cause of the elderly
Dehydration (20%):
Relatively simple water deficiency, causing the reduction of extracellular fluid, due to increased blood osmotic pressure, compensatory thirst drinking water and increased renal tubular reabsorption, but the elderly have limited compensation, especially at the same time When accompanied by sodium loss, often combined capacity is insufficient.
Excessive discharge (30%):
Plasma hyperosmotic state, such as hyperglycemia caused by osmotic diuretic; diabetes insipidus, due to insufficient secretion of ADH or tubular insensitivity to ADH leading to excessive renal drainage; severe vomiting or diarrhea, or nasogastric drainage or gastrointestinal Abnormal loss such as switch, high fever, sweating, tracheotomy, chronic kidney disease, diuretic application and other pathological loss; in addition, special attention is paid to the elderly's adrenal insufficiency.
Insufficient intake (20%):
Older people are less eager to drink, and critically ill patients have difficulty drinking water. People with disturbance of consciousness do not know how to drink.
Prevention
Dehydration prevention for the elderly
In addition to observing the patient's urine volume and blood pressure during rehydration, it is best to monitor central venous pressure (CVP), especially those with suspected cardiac dysfunction. Active treatment of primary disease and complications.
1. When isotonic dehydration has hypovolemic shock, simple rehydration is forbidden.
2. Hypotonic dehydration is contraindicated with early supplementation of 5% or 10% glucose solution.
3. Hyperosmolar dehydration occurs when severe hypernatremia occurs, it is contraindicated to quickly enter hyperosmotic syrup, so as not to aggravate brain edema.
4. Pay attention to the psychological balance and avoid excessive excitement in spirit and emotion.
5. Prevent various infections, maintain physical strength, and avoid fatigue.
Complication
Dehydration complications in the elderly Complications, sacral neuropathy, fainting, coma, shock
Patients with severe dehydration may have neurological symptoms such as paralysis, mania or fainting, as well as unconsciousness, coma, circulatory failure, shock, etc.
Symptom
Dehydration symptoms in the elderly Common symptoms Drinking hypotension, lethargy, hyponatremia, mucous membrane dryness, dizziness, dehydration, blood concentration, low blood pressure, low coma
The common manifestations of dehydration in the elderly are weakness, dizziness, and abnormal personality. Although obvious oral mucosa is dry, patients may not have obvious thirst and polydipsia behavior. In severe cases, they often show signs of change (including hallucinations, proverbs, and lethargy). Or coma), decreased urine output (due to hypertonic diuresis caused by dehydration, early urine output increased), hypotension, increased hematocrit, but poor skin elasticity can also be seen in normal elderly, serum urea nitrogen (BUN) and creatinine Elevated levels of (Cr) often indicate a significant lack of capacity; serum sodium levels can be high, low, and normal, depending on the cause of dehydration.
Examine
Examination of dehydration in the elderly
Increased urine specific gravity, blood sodium concentration >145mmol / L called hypertonic dehydration, blood sodium <130mmol / L called hypotonic dehydration, water and sodium ratio is said to be isotonic dehydration, white blood cell count increased, hemoglobin increased, BUN, Cr increased, etc. .
X-ray examination, no abnormalities in the heart and lungs.
Diagnosis
Identification of dehydration diagnosis in the elderly
Diagnostic criteria
Dehydration can be diagnosed based on the cause and clinical manifestations; laboratory tests can help determine the cause and extent of dehydration.
1. Reasons for dehydration
Usually the patient's urine Na + concentration <10 ~ 15mmol / L, if caused by kidney disease, diuretic, osmotic diuretic, adrenal insufficiency, etc., urine Na + concentration can be > 20mmol / L, urine osmotic pressure > 450mOsm / kg, The blood BUN/Cr ratio is often >20:1.
2. The degree of water shortage
(1) Clinically estimated urine output, normal blood pressure, the amount of dehydration is about 2% of body weight; urine volume is reduced, blood pressure is low, and skin elasticity is significantly reduced, the amount of dehydration has reached 5% of body weight; urine volume is significantly reduced The blood pressure is significantly reduced, the amount of dehydration has exceeded 6% of body weight.
(2) Formula calculation:
1 Calculated according to blood sodium concentration:
Water deficiency (L) = 0.5 × body weight (kg) × (Na + -140) ÷ 140
Applicable to those who are simply dehydrated; if they are suffering from severe sodium loss, they are no longer suitable.
2 Calculated according to hematocrit (Hct):
Water deficiency (L) = 0.2 × body weight (kg) × (Hct measured - Hct normal) ÷ Hct normal
Not applicable to patients with bleeding.
Differential diagnosis
Clinical need to distinguish between isotonic dehydration, hypertonic dehydration, hypotonic dehydration, but also need to pay attention to the relationship between dehydration and water toxicity, hypernatremia, hyponatremia and their mutual transformation.
