concentration of 2% to 2.5% Soda, juice, popsicles, and soups are inappropriate rehydration solutions in dehydrated infants and children and should be discouraged as they not have the appropriate glucose-to-sodium ratio and are not absorbed as easily as electrolyte solutions Studies have evaluated half strength apple juice (mixed with water) as an alternate therapy as compared to ORT and have found fewer treatment failures most likely secondary to patient taste preference In developing countries, the addition of zinc supplementation in patients older than months of age with diarrhea has been shown to have improved outcomes however current evidence does not show a benefit in wellnourished children in settings with low prevalence of zinc deficiency TABLE 22.4 ONDANSETRON DOSING FOR GASTROENTERITIS Patient weight (kg) Dose 8–15 >15–30 >30 2-mg orally disintegrating tablet (½ tablet) 4-mg orally disintegrating tablet 8-mg orally disintegrating tablet The amount of fluid to be administered is dependent on the degree of dehydration Mild dehydration reflects up to 5% weight loss, so 5% of the child’s body weight (50 mL/kg) should be administered as small-volume frequent feeds Moderate dehydration represents up to 10% weight loss, so 10% of the child’s weight (100 mL/kg) should be administered An easy rule of thumb to remember is that a mildly dehydrated patient can receive mL/kg every minutes and a moderately dehydrated patient can receive mL/kg every minutes As the child tolerates the feeds, the volume can be increased as well as the frequency The rehydration should be completed over a 4-hour time frame ( Fig 22.2 ) ORT has been shown to be equivalent to IV fluid therapy in terms of rehydration efficacy and it has been shown that it takes less time to institute therapy with ORT (i.e., teach the parents how to administer the fluids) than to start an IV line in a child, and there is less staff time involved in administering care to these patients as well as shorter ED stays There are a significant number of patients with gastroenteritis who will be unable to perform ORT and will subsequently require alternative methods for rehydration Nasogastric (NG) tube use is an acceptable alternative as it has been shown to be as effective as IV hydration They are relatively easy to place, not need radiographic confirmation of placement, and the patient does not need to remain awake while receiving the rehydration solution A small feeding tube is better tolerated for fluid administration than a larger NG tube Since NG tubes are considered a very noxious intervention, practitioners and parents may choose parenteral rehydration over NG FIGURE 22.2 Oral rehydration therapy Parenteral Rehydration Approximately 20% of patients will be unable to tolerate oral syringe administration of ORT because of persistent vomiting, high stool outputs, or inability to cooperate If the patient is unable to tolerate ORT or is severely dehydrated, then administration of 20-mL/kg boluses of isotonic saline or lactated Ringer solution intravenously would be appropriate The number of boluses required depends on the patient’s physiologic response to the fluid that has been administered Once the initial resuscitation phase is completed, the patient will need to be reassessed to see if maintenance fluids are necessary for ongoing losses or continued inability to tolerate ORT For ages 28 days to 18 years, the recommended maintenance fluid is D5NS with 20 mEq/L of potassium chloride Notable exceptions include patients with extremely voluminous watery diarrhea, major burn patients who continue to require isotonic fluids, children with diabetic ketoacidosis who not require dextrose initially, and children with severe metabolic derangements where rapid correction will lead to severe complications The fluid rate is determined by the estimated fluid deficit, ongoing losses, and maintenance fluid requirements ( Fig 22.3 ) Usually, 50% of the child’s fluid deficit is given over the first hours in addition to one-third of the daily maintenance fluid requirements In hypertonic states, after initial stabilization with isotonic fluids, the replacement solution is given more slowly to allow equilibration across the blood–brain barrier (see Chapter 100 Renal and Electrolyte Emergencies ) Parenteral rehydration via an IV catheter has been used extensively The advantages of IV rehydration are numerous including familiarity with the procedure, widespread acceptance, and direct vascular access to rehydrate a patient There are disadvantages associated with IV catheter use, primarily difficulty in obtaining access in dehydrated children, particularly those younger than years, pain associated with placement, and the time and resources required for placement Subcutaneous rehydration is a method to deliver fluids parenterally that was common prior to the widespread use of IV catheters There is evidence that using human recombinate hyaluronidase (Hylenex) with a subcutaneous catheter may be an alternative for mild and moderately dehydrated children who have failed ORT It is a method that can also be used as a bridge to getting IV access in severely dehydrated patients however intraosseous access should also be considered in the severely ill Hyaluronidase temporarily dissolves hyaluronic acid and allows fluid to be administered subcutaneously, which is subsequently absorbed into the vascular system Advantages of subcutaneous fluid administration include ease of placement and decreased pain with insertion More research in this new modality is required FIGURE 22.3 Calculation of deficit therapy using the example of a child with estimated 10% dehydration and emergency department (ED) weight of kg CONCLUSION ... Calculation of deficit therapy using the example of a child with estimated 10% dehydration and emergency department (ED) weight of kg CONCLUSION