• Knowledgebase: Vomiting and Diarrhea Questions

    Questions about the management of Vomiting and Diarrhea.

    3. The Oral Rehydration Therapy: Canadian Journal of Peds - Top

    The Canadian Journal of Paediatrics 1994; 1(5): 160-164

    Oral rehydration therapy with an inexpensive glucose and electrolyte solution as promoted by the World Health Organization has reduced substantially the number of deaths from dehydration due to diarrhea. In addition, recent research suggests that these solutions have advantages over conventional therapy. Yet, oral rehydration therapy has not been used extensively in developed countries.

    Acute gastroenteritis is one of the most common illnesses affecting infants and children in Canada and the world. The average child under age 5 experiences 2.2 diarrheal episodes per year.1 Treatment from resulting dehydration accounts for an estimated 200,000 hospitalizations per year in the U.S.2 with comparable rates occurring in Canada. Worldwide as many as 4,000,000 children per year die as a result of gastroenteritis and resulting malnutrition. Prolonged diarrhea and malnutrition are a primary cause of morbidity and mortality in Canadian native populations.

    Oral rehydration therapy (ORT), using a simple, inexpensive, glucose and electrolyte solution promoted by the World Health Organization (WHO) has reduced the number of deaths from dehydration due to diarrhea by about a million per year.1,3 In spite of its efficacy, ORT has not been used extensively in developed countries. Recent research, summarized in this report, suggests that the use of oral rehydration solutions have advantages over conventional therapy. In an effort to encourage the use of ORT, a simple approach to rehydration is outlined.

    Oral rehydration takes advantage of glucose-coupled sodium transport,4 a process for sodium absorption which remains relatively intact in infective diarrheas due to viruses or to enteropathogenic bacteria, whether invasive or enterotoxigenic. Glucose enhances sodium, and secondarily, water transport across the mucosa of the upper intestine.5 For optimal absorption, the composition of the rehydration solution is critical. The amount of fluid absorbed depends on three factors: the concentration of sodium, the concentration of glucose and the osmolality of the luminal fluid. Maximal water uptake occurs with a sodium concentration from 40 to 90 mmol/L, a glucose concentration from 110 to 140 mmol/L (2.0 to 2.5 g/100 mL) and an osmolality of about 290 mOsm/L, the osmolality of body fluids.6 Increasing the sodium beyond 90 mmol/L may result in hypernatremia; increasing the glucose concentration beyond 200 mOsm/L, by increasing the osmolality of the solution, may result in a net loss of water. CHO to Na ratio should not exceed 2:1 in these solutions.

    For practical purposes in Canada, rehydration can be accomplished using solutions with higher sodium, i.e., 75-90 mmol/L. These are termed rehydration solutions (ORS). Prophylaxis of dehydration and maintenance involve solutions with 45-60 mmol/L of sodium. These are termed maintenance solutions. High sodium rehydrating solutions used to treat acute dehydration may be used for maintenance by giving the solution alternately on a 1-to-1 basis with a no-sodium or low-sodium fluid such as water, low CHO fluids, or breast milk. The high sodium ORS should not be used as the sole fluid intake for maintenance of hydration. Fruit juices and pop are not efficacious because of their high carbohydrate concentration, osmolality and the inadequate sodium concentration.7 Individualized dietary management of the patient during acute diarrhea is the key and should be emphasized.

    Oral rehydration and maintenance solutions presently in use, although effective in rehydration, do not decrease stool volume because of the relatively high osmolality of the glucose which they contain. The challenge, therefore, is to provide adequate glucose to the sodium pump without increasing the osmolality of the rehydration solution.

    This has been done successfully by substituting short chain glucose polymers (starch) from rice and other cereals for glucose in the oral rehydration mixture.8 In field trials in developing countries,8,9 ORS containing glucose polymers, primarily from rice and corn, were found not only to be as effective in correcting dehydration as glucose-based ORS, but also to offer the additional advantage of reducing the amount and duration of diarrhea by 30%, thereby reducing morbidity and costs of treatment and increasing acceptability. The effectiveness in diarrhea typical of North America may be less marked, i.e., reducing stool output by 18%.

    Defined short-chained glucose polymers from rice may also be safe and effective in the treatment of acute diarrhea.10 Wapnir et al11 found that a solution containing 30 g/L of rice syrup solids (180 mOsm/L) resulted in 40% more water absorption than a similar solution which contained 20 g/L of glucose (230 mOsm/L). A clinical study with solutions containing rice-syrup solids confirmed their efficacy in the rehydration of infants with acute diarrhea. Further, such solutions decreased stool output, and promoted greater absorption and retention of fluid and electrolytes than did a glucose-based solution.12

    Amino acids have also been suggested as additives to ORS. The addition of alanine alone to the WHO oral rehydration solution (ORS) was not found to give additional benefits.13 However, Khin-Maung-U and Greenough8 found that alanine, added to a glucose polymer-based ORS, decreased the amounts of stool by a further 10% to 40%. Nevertheless, these are not currently recommended by WHO. Rice-based corn and lentil-based oral rehydration solutions have been extensively tested and may eventually be made available.

    Along with improved oral rehydration solutions have come advances in the field of early refeeding. Fasting has been shown to prolong diarrhea. This may be due to undernutrition of the bowel mucosa which delays the replacement of mucosal cells destroyed by the infection. Although there is general agreement that breast-feeding should continue in spite of diarrhea,14 early refeeding with a lactose-containing formula is usually well tolerated.15 Early refeeding should commence 6-12 hours into therapy.

    On the basis of these findings and recent recommendations,16 the following principles should be followed in treating diarrheal disease:

    Fluid therapy should include the following three elements: rehydration, replacement of ongoing losses, and maintenance.
    Fluid therapy is based on an assessment of the degree of dehydration present. Principles are as follows:
    No dehydration - If diarrhea is present, but urinary output is normal, the normal diet and breast-feeding may continue at home with fluid intake dictated by thirst. High osmolality fluids such as undiluted juices should be avoided, and maintenance oral electrolyte solution (Na 45-60 mmol/L) offered "ad libitum."

    Mild - If symptoms and signs are limited to decreased urinary output and increased thirst, mild dehydration is suspected. Assessment and treatment under close supervision are indicated. Rehydration consists of ORS or maintenance solution 10 mL/kg/hr with reassessment at 4-hour intervals. Breast-feeding continues. Early refeeding with the child's customary formula at the usual concentration is recommended. Extra ORS or maintenance solution (e.g., 5-10 mL/kg) may be given after each stool if diarrhea persists.

    Moderate - If at least two of the following signs, sunken eyes, loss of skin turgor ("tenting" of abdominal skin lasting less than 2 seconds), or dry buccal mucous membranes are present, moderate dehydration is diagnosed and rehydration consisting of ORS 15-20 mL/kg/hr with direct observation and reassessment at 4-hour intervals. If dehydration is corrected, therapy for ongoing losses and maintenance are continued as outlined above. If not, treatment is repeated as indicated by clinical signs or symptoms.

    Severe - If, in addition to signs of moderate dehydration, there is rapid breathing, lethargy, coma, a rapid thready pulse or "tenting" of the skin lasting more than 2 seconds, severe dehydration and shock are present. Blood pressure should be measured. Prompt intravenous therapy is indicated with rapid infusion of saline plasma or colloid sufficient to replete blood volume (10-20 mL/kg over 30 minutes may be necessary). Intraosseous infusion should be used if an intravenous line cannot quickly be inserted.
    General comments. Vomiting is not a contraindication to ORT. ORS should be given slowly but steadily to minimize vomiting. Fluids may be administered by nasogastric tube if required. The child's clinical condition should be frequently assessed. A child should never be kept on ORS fluid alone for more than 24 hours. Early refeeding should begin within 6 hours. A full diet should be reinstituted within 24 to 48 hours, if possible.

    There are certain contraindications to the use of ORT:

    -Protracted vomiting despite small, frequent feedings
    -Worsening diarrhea and an inability to keep up with losses
    -Stupor or coma
    -Intestinal ileus.

    As ORS can be administered easily by a properly instructed parent, and because dehydration can be corrected quickly, it lends itself well for use in an outpatient department or nursing station. At the end of 4 hours, the child can either be sent home on maintenance therapy or, if dehydration persists, be observed for further therapy. Intelligent use of ORT can decrease hospital admissions, an important consideration in a time of decreasing hospital budgets. Although in our society intravenous therapy is often considered more convenient than ORT, clinicians should feel more comfortable as they become more accustomed to the use of ORT.

    TABLE 3: Simplified ORT protocol in mild to moderate rehydration

    mild moderate
    1st hour 20 mL/kg/hr 20 mL/kg/hr
    next 6-8 hours 10 mL/kg/hr 15-20 mL/kg/hr

    Reassessment at 4-hour intervals

    There are many different equations for calculating administration rates in oral rehydration. ORT may be given in amounts equal to
    fluids calculated for intravenous administration. Alternately, fluids may be delivered by nasogastric tube



    Recommendations
    Dehydration accompanying infantile gastroenteritis should be treated with early oral rehydration and early refeeding strategies.
    Infants with gastroenteritis should be offered maintenance solution to prevent dehydration. Parents and daycare centres should keep maintenance solution on hand in anticipation of episodes of infectious diarrhea.
    ORS and maintenance solutions and instructions in their use should be made available at reasonable costs.
    Medical facilities should have ORT protocols available for staff and patients.
    Antidiarrheal drugs, antibiotics and antiemetic therapy are rarely indicated in gastroenteritis in childhood and should be discouraged.
    Home-made oral rehydration solutions are discouraged since serious errors in formulation have occurred.
    Infants with mild to moderate dehydration should be treated under medical supervision with ORT in preference to intravenous rehydration.
    Infants with severe dehydration should initially be treated with intravenous or intraosseous rehydration.
    Breast-fed infants with dehydration should be given ORT in conjunction with continued breastfeeding.
    Early refeeding should commence as soon as vomiting has resolved, approximately 6-12 hours.
    Non-lactose containing formulae or milks may be used if diarrhea and abdominal cramps persist beyond expected 5- to 7-day course suggesting clinical lactose intolerance.
    Further initiatives to encourage ORT use by patients and professionals should be developed.


    - Updated: March 10, 2001

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    • James L Horwitz, MD

    David C. Thomas, MD

    Barbara Lindberg, PNP