Dehydration Treatment & Management

Hydration and nutrition are the interventions with the greatest impact on the course of acute diarrhea. ^{[13, 14]} The use of clinical dehydration scales/scores for the evaluation of the severity of dehydration and early initiation of rehydration may positively impact outcomes. ^{[14, 15]}

Medications such as loperamide, opiates, anticholinergics, bismuth subsalicylate, and adsorbents are not recommended in dehydration because of questionable efficacy and potential adverse effects.

Severe dehydration warrants hospital admission for rehydration with isotonic saline, as do hypernatremic or hyponatremic states. ^[13]

Inability to tolerate oral rehydration therapy (ORT) may necessitate hospital admission for nasogastric or intravenous fluid therapy.

Oral rehydration solutions

During gastroenteritis, the intestinal mucosa retains absorptive capacity. Sodium and glucose in the correct proportions can be passively cotransported with fluid from the gut lumen into the circulation. Rapid oral rehydration with the appropriate solution has been shown to be as effective as intravenous fluid therapy in restoring intravascular volume and correcting acidosis.

Table 3. Composition of Appropriate Oral Rehydration Solutions (Open Table in a new window)

The World Health Organization (WHO) and United Nations International Children's Emergency Fund (UNICEF) have a standard and reduced osmolarity formulation of their oral rehydration solution.

Table 4. WHO-UNICEF Oral Rehydration Solutions (Open Table in a new window)

All of the commercially available rehydration fluids are acceptable for oral rehydration therapy (ORT). They contain 2-3 g/dL of glucose, 45-90 mEq/L of sodium, 30 mEq/L of base, and 20-25 mEq/L of potassium. Osmolality is 200-310 mOsm/L.

In children with severe acute malnutrition and diarrhea, low osmolarity oral rehydration solution (ORS) (osmolarity: 245, sodium: 75 mEq/L) with added potassium (20 mmol/L) appears to be equally effective for successful rehydration as modified World Health Organization–recommended rehydration solution (ReSoMal) (osmolarity: 300, sodium: 45 mEq/L) but achieves rehydration more quickly. ^[18] Both solutions also correct for hypokalemia, but hyponatremia may affect fewer children with the low-osmolarity ORS formulation. These findings indicate that the low osmolarity ORS may be an option in regions where ReSoMal is not available (eg, India). ^[18]

Table 5. Composition of Inappropriate Oral Rehydration Solutions (Open Table in a new window)

Traditional clear fluids are not appropriate for ORT. Many contain excessive concentrations of CHO and low concentrations of sodium. The inappropriate glucose-to-sodium ratio impairs water absorption, and the large osmotic load creates an osmotic diarrhea, further worsening the degree of dehydration.

ORT for mild or moderate dehydration

Mild or moderate dehydration can usually be treated very effectively with ORT. ^[19]

Vomiting is generally not a contraindication to ORT. If evidence of bowel obstruction, ileus, or acute abdomen is noted, then intravenous rehydration is indicated.

Calculate the fluid deficit. Physical findings consistent with mild dehydration suggest a fluid deficit of 5% of body weight in infants and 3% in children. Moderate dehydration occurs with a fluid deficit of 5-10% in infants and 3-6% in children (see Table 1 and Table 2). The fluid deficit should be replaced over 4 hours. Documented recent change in weight remains the standard for calculating fluid deficit if the values are available. (This is especially helpful with infants since they have relatively frequent well childcare visits that include weight checks.)

The oral rehydration solution should be administered in small volumes very frequently to minimize gastric distention and reflex vomiting. Generally, 5 mL of oral rehydration solution every minute is well tolerated. Hourly intake and output should be recorded by the caregiver. As the child becomes rehydrated, vomiting often decreases and larger fluid volumes may be used.

If vomiting persists, infusion of oral rehydration solution via a nasogastric tube may be temporarily used to achieve rehydration. Intravenous fluid administration (20-30 mL/kg of isotonic sodium chloride 0.9% solution over 1-2 h) may also be used until oral rehydration is tolerated. According to a Cochrane systematic review, for every 25 children treated with ORT for dehydration, one fails and requires intravenous therapy. ^[20]

Replace ongoing losses from stools and emesis (estimate volume and replace) in addition to replacing the calculated fluid deficit.

An age appropriate diet may be started as soon as the child is able to tolerate oral intake.

Severe dehydration

Laboratory evaluation and intravenous rehydration are required. The underlying cause of the dehydration must be determined and appropriately treated.

Phase 1 focuses on emergency management, the restoration of hemodynamic integrity. Severe dehydration is characterized by a state of hypovolemic shock requiring rapid treatment. Initial management includes placement of an intravenous or intraosseous line and rapid administration of 20 mL/kg of an isotonic crystalloid (eg, lactated Ringer solution, 0.9% sodium chloride). Additional fluid boluses may be required depending on the severity of the dehydration. The child should be frequently reassessed to determine the response to treatment. As intravascular volume is replenished, tachycardia, capillary refill, urine output, and mental status all should improve. If improvement is not observed after 60 mL/kg of fluid administration, other etiologies of shock (eg, cardiac [may be more apparent following the initial fluid bolus before reaching 60 mL/kg – evidence of a gallop on examination, rales], anaphylactic, septic) should be considered. Hemodynamic monitoring and inotropic support may be indicated.

Phase 2 focuses on unaddressed deficit replacement after phase 1, provision of maintenance fluids, and replacement of ongoing losses. Maintenance fluid requirements are equal to measured fluid losses (urine, stool) plus insensible fluid losses. Normal insensible fluid loss is approximately 400-500 mL/m² body surface area and may be increased by factors such as fever and tachypnea.

Alternatively, daily maintenance (not including pathologic ongoing loss) fluid requirements may be roughly estimated as follows:

• Less than 10 kg = 100 mL/kg

• 10-20 kg = 1000 + 50 mL/kg for each kg over 10 kg

• Greater than 20 kg = 1500 + 20 mL/kg for each kg over 20 kg

Severe dehydration by clinical examination suggests a fluid deficit of 10-15% of body weight in infants and 6-9% of body weight in older children. The daily maintenance fluid is added to the fluid deficit. In general, the recommended administration is one half of this volume administered over 8 hours and administration of the remainder over the following 16 hours. Continued losses (eg, emesis, diarrhea) must be promptly replaced.

If the child is isonatremic (130-150 mEq/L), the sodium deficit incurred can generally be corrected by administering the remaining fluid deficit after phase 1 plus maintenance as 5% dextrose in 0.45-0.9% sodium chloride. Potassium (20 mEq/L potassium chloride) may be added to maintenance fluid once urine output is established and serum potassium levels are within a safe range.

An alternative approach to the deficit therapy approach is rapid replacement therapy. With this approach, a child with severe isonatremic dehydration is administered 20-40 mL/kg of isotonic sodium chloride solution or lactated Ringer solution over 15-60 minutes. As perfusion is restored, the child improves and is able to tolerate an oral rehydration solution for the remainder of his rehydration. This approach is not appropriate for hypernatremic or hyponatremic dehydration.

Hyponatremic dehydration

Phase 1 management of hyponatremic dehydration is identical to that of isonatremic dehydration. Rapid volume expansion with 20 mL/kg of isotonic (0.9%) sodium chloride solution or lactated Ringer solution should be administered and repeated until perfusion is restored.

Severe hyponatremia (< 130 mEq/L) indicates additional sodium loss in excess of water loss. In phase 2 management, rehydration is calculated as for isonatremic dehydration. The additional sodium deficit must be calculated and added to the rehydration fluids. The deficit may be calculated to restore the sodium to 130 mEq/L and administered over 48 hours, as follows:

• Sodium deficit = (sodium desired - sodium actual) X volume of distribution X weight (kg)

• Example: Sodium = 123, weight = 10 kg, assumed volume of distribution of 0.6; Sodium deficit = (130-123) X 0.6 X 10 kg = 42 mEq sodium

A simplified approach is to use 5% dextrose in 0.9% sodium chloride as the replacement fluid. The sodium is closely monitored, and the amount of sodium in the fluid is adjusted to maintain a slow correction (about < 0.5 mEq/L/h, with a correction goal of 8 mEq/L over 24 hours).

Frequently reassessing the serum sodium level during correction is imperative. Rapid correction of chronic hyponatremia (>2 mEq/L/h) has been associated with central pontine myelinolysis. Rapid partial correction of symptomatic hyponatremia has not been associated with adverse effects. Therefore, if the child is symptomatic (seizures), a more rapid partial correction is indicated. Hypertonic (3%) sodium chloride solution (0.5 mEq/mL) may be used for rapid partial correction of symptomatic hyponatremia. A bolus dose of 4 mL/kg raises the serum sodium by 3-4 mEq/L.

Hypernatremic dehydration

Phase 1 management of hypernatremic dehydration is identical to that of isonatremic dehydration. Rapid volume expansion with 20 mL/kg of isotonic sodium chloride solution or lactated Ringer solution should be administered and repeated until perfusion is restored.

Varied regimens may be successfully followed to achieve correction of severe hypernatremia (>150 mEq/L). In phase 2 management, the most important goal is to reestablish intravascular volume if not done already in stage 1 and return serum sodium levels toward the reference range by not more than 10 mEq/L/24h. Rapid correction of hypernatremic dehydration can have disastrous neurologic consequences, including cerebral edema and death.

The most cautious approach is to plan a slow correction of the fluid deficit over 48 hours. Following adequate intravascular volume expansion, rehydration fluids should be initiated with 5% dextrose in 0.9% sodium chloride. Serum sodium levels should be assessed every 2-4 hours. If the sodium has decreased by less than 0.5 mEq/L/h, then the sodium content of the rehydration fluid is decreased. This allows for a slow controlled correction of the hypernatremic state.

Hyperglycemia and hypocalcemia are sometimes associated with hypernatremic dehydration. Serum glucose and calcium levels should be closely monitored.

Pharmacologic management

Note the following:

• Antidiarrheal agents are not recommended because of a high incidence of side effects including lethargy, respiratory depression, and coma.

• Routine empiric antibiotics should be avoided and may worsen some specific diarrheal disease states (eg, hemolytic-uremic syndrome, Clostridium difficile).

• Over-the-counter antiemetics are not recommended due to side effects including drowsiness and impaired oral rehydration.

• In a study of 170 children aged 3 months to 5 years with acute diarrhea with vomiting and some dehydration, those who received treatment with a single dose of oral ondansetron (n = 85) and standard dehydration protocols showed faster rehydration, fewer vomiting episodes, and better caregiver satisfaction than those who were administered placebo and standard management of dehydration (n = 85). ^[21]

• In an emergency department study, ondansetron has been shown to decrease likelihood of vomiting, increase oral intake, and decrease emergency department length of stay but has not shown significant effects on hospitalization rates or long-term outcomes. ^[22]

• In a more recent study of 1313 Italian children with acute gastroenteritis, investigators found that in children for whom initial oral rehydration failed, a single oral dose of ondansetron reduced the need for intravenous hydration as well as the percentage of those who continued to vomit. ^[23] In comparison, domperidone was ineffective for symptomatic relief of vomiting during acute gastroenteritis.

• Dimenhydrinate, although used in Europe and Canada, has not been found to improve oral rehydration. ^[24]

ORT may be continued at home if clear instructions are provided for the family and if the family members can be relied upon to carry out the hydration regimen. Close follow-up by the primary physician is recommended.

Children with dehydration from gastroenteritis have decreased duration of diarrhea when feedings are started as soon as the patient is able to tolerate oral intake.

Diluting milk or formula is not indicated. Breast-feeding should be resumed as soon as possible.

Foods that contain complex carbohydrates (eg, rice, wheat, potatoes, bread, cereals), lean meats, fruits, and vegetables are encouraged. Fatty foods and simple carbohydrates should be avoided.

Consider rotavirus vaccination in infants, as rotavirus infection may cause diarrhea and/or vomiting, which can sometimes be severe enough to lead to dehydration. ^[25] Indeed, rotavirus infection is the principal cause of severe diarrhea in this population. ^[26] Infants who should not receive rotavirus vaccine include those who have (1) severe combined immunodeficiency (SCID), (2) immune deficiency from other causes (eg, HIV/AIDS, cancer, steroid therapy), and (3) a history of intussusception. ^[25]

In a study of hospitalizations for pediatric dehydration, Shanley et al found evidence that a large number of these hospitalizations were preventable. The study involved 85 children (mean age 1.6 y) who were diagnosed with dehydration, with a cross-sectional survey conducted of the children’s primary care physicians (PCP), inpatient attending physicians, and parents to determine factors contributing to their hospitalization. In 12% of cases, there was unanimous agreement between the PCP, attending physician, and parent that the hospitalization could have been prevented, while in 45% of cases at least one of these believed that the hospitalization was preventable.

Based on the survey, reasons that the preventable hospitalizations occurred included the following ^[27] :

• Insufficient education of parents by physicians

• Inadequate rehydration of the child at home

• Delays in seeking health care

• Cost and insurance factors

• Inappropriate hospital admissions

• Inadequate health-care quality

• Dissatisfaction of parents with their PCPs