Dehydration rehydration therapy

Worldwide, dehydration is especially problematic for children younger than age 5. However, the highest rate of death in the United States occurs among the elderly.5 Rehydration is the foundation of therapy for GI infections, and oral rehydration therapy (ORT) is usually preferred (Table 73-1). 

The movement of Na+ and glucose from the lumen of the intestine across the epithelial cell to the blood sets up a difference in osmotic pressure across the cell. As a result, water flows through the cell, across the apical and basolateral membranes by simple diffusion. Hence the uptake of water requires both Na+ and glucose (or amino acids) to be present in the lumen of the intestine. The presence of water alone in the lumen of the intestine is much less effective. This is the basis of glucose rehydration therapy as a remedy for dehydration a solution of glucose and salt (NaCl) is administered to the patient. This is a simple, inexpensive but extremely important treatment which has saved the lives of many infants in developing countries who would have otherwise died of the effects of dehydration, usually associated with diarrhea. 

Oral rehydration therapy is a simple, cheap and effective treatment for diarrhoea-related dehydration, such as that caused by cholera or rotavirus. It consists of a solution of salt and glucose and is administered orally. It has saved millions of children from diarrhoea, stiU a leading cause of death, particularly in the developing world. The standard manufactured WHO/UNICEF solution contains ... 

After startiug rehydration therapy, parents should be instructed to observe the child for a reversal of the signs of dehydration, increased stool consistency, and decreased stool frequency. If ORT is not improving the fluid status and the patient continues to produce frequent, large-volume watery stools, close supervision with medical support is justifled. ... 

Oral rehydration therapy (ORT) is a simple and effective way to treat or prevent dehydration and the accompanying electrolyte loss, especially if the dehydration is caused by diarrhea. Oral rehydration therapy was developed in the 1950s for use in developing countries where diarrhea-producing diseases like cholera, combined with unsanitary water and food, cause the death of an estimated 4 million children annually. The threat to children in developed countries is not nearly as great an estimated 500 children die annually from diarrhea in the United States. 

Every year, oral rehydration therapy (ORT)—the feeding of an electrolyte solution—saves the lives of countless children worldwide who become severely dehydrated as a result of diarrhea. One requirement of the solution used is that it be isotonic with human blood. 

The rehydration phase aims to replace extravascular fluid losses. Crystalloid fluids are a logical choice for rehydration as they readily diffuse into the interstitial fluid from the vasculature (Spalding Goodwin 1999, Vaupshas Levy 1990). Rehydration should take place over the first 12-24 h of therapy. The amount given should be based on the clinical estimate of the degree of dehydration and the response to fluid therapy. 

Rehydration and maintenance of water and electrolytes are primary treatment goals until the diarrheal episode ends. If the patient is volume depleted, rehydration should be directed at replacing water and electrolytes to normal body composition. Then water and electrolyte composition are maintained by replacing losses. Many patients will not develop volume depletion and therefore will only require maintenance fluid and electrolyte therapy. Parenteral and enteral routes may be used for supplying water and electrolytes. If vomiting and dehydration are not severe, enteral feeding is the less costly and preferred method. In the United States, many commercial oral rehydration preparations are available (Table 36-3). 

For those patients with normal to moderately impaired renal function, the cornerstone of initial treatment of hypercalcemia is volume expansion to increase urinary calcium excretion (see Table 49-6). Patients with severe renal insufficiency usually do not tolerate volume expansion they may be initiated on therapy with calcitonin. Patients with symptomatic hypercalcemia are often dehydrated secondary to vomiting and polyuria thus rehydration with saline-containing fluids is necessary to interrupt the stimulus for sodium and calcium reabsorption in the renal mbule. ° Rehydration can be accomplished by the infusion of normal saline at rates of 200 to 300 mL/h, depending on concomitant conditions (primarily cardiovascular and renal) and extent of hypercalcemia. Adequacy of hydration is assessed by measuring fluid intake and output or by central venous pressure monitoring. Loop diuretics such as furosemide (40 to 80 mg IV every 1 to 4 hours) or ethacrynic acid (for patients with sulfa allergies) may also be instiffited to increase urinary calcium excretion and to minimize the development of volume overload from the administration of saline (see Table 49-6). Loop diuretics such as furosemide... 

An understanding of osmosis and the intestinal absorption of salt and glucose forms the basis for a simple therapy that saves millions of lives each year, particularly in less-developed countries. In these countries, cholera and other intestinal pathogens are major causes of death of young children. A toxin released by the bacteria activates chloride secretion by the intestinal epithelial cells into the lumen water follows osmotlcally, and the resultant massive loss of water causes diarrhea, dehydration, and ultimately death. A cure demands not only killing the bacteria with antibiotics, but also rehydration— replacement of the water that is lost from the blood and other tissues. 

---