The dog days of summer have passed us by and with it the fear of overheating, excessive sweating, and dehydration. However, the colder weather brings a return of the flu and the swine flu last year caused a lot of vomiting. Dehydration is caused by an imbalance between fluid going in and fluid going out. In the summer, excessive sweating (fluid loss) and not enough fluid intake can cause dehydration. In the winter, vomiting due to illness, causes poor intake and some fluid loss. Vomiting combined with diarrhea as additional fluid loss, as in the typical gastroenteritis, can lead to severe dehydration. Less commonly, excessive urination can cause dehydration as well as the inability to drink, possibly from a sore throat or mouth sores. The ultimate treatment is fluid replacement. However, in practice, the issue is not quite as clear. Dehydration can be difficult to assess and there are multiple options for fluid replacement each with its own pros and cons.
Dehydration is graded from mild to moderate to severe. Mild to moderate is characterized by dry mouth, lack of tears, and decreased urination. Most children will only suffer from mild to moderate dehydration, even when vomiting a lot or with profuse diarrhea. Severely dehydrated children can be lethargic and look very sick. This is a true emergency because of the potential for the lack of fluid to compromise blood flow to the brain and kidneys.
Once the decision to intervene has been made, there are several options for fluid replacement, each with advantages and drawbacks. Those options range from utilizing the gut to direct intravascular (IV) access.
Oral rehydration therapy (ORT) is clearly the first choice in rehydration for anything less than severe dehydration. ORT can be delivered in two ways. Most commonly children are able to drink fluid directly. This has the benefit of easy delivery, although it requires the understanding and cooperation of the caregiver and child. The key is to start giving small amounts of fluid, no more than a teaspoon, and frequently (every 5 minutes). Once that is tolerated over an hour, larger amounts can be tried. The most common mistake is giving the child too much fluid at once because the large volume can make the child vomit. Rehydration fluids that can be bought in any drugstore or even made at home using recipes found online (the WHO formula) are preferred, but in most cases any fluid will do. Try and stay away from apple juice because it can exacerbate diarrhea. Less commonly, the mouth can be bypassed with an oral-gastric or a nasal-gastric tube so that fluid is directly delivered to the stomach. This method maintains the benefit of utilizing gastrointestinal absorption although many children do not like having the tube in place. All of these methods are subject to the ability of the child to tolerate the fluid so that the vomiting child may not be a good candidate. In those cases, where vomiting is preventing fluid intake a trial of an anti-emetic drug to stop the vomiting is indicated. Multiple studies have shown that ORT is usually successful if done correctly and patiently. Moreover, ORT can usually be done at home, saving a trip to the doctor or ER.
In cases of severe dehydration or if ORT has failed the current rehydration strategy most often used is intravenous (IV). Although often used as first line therapy for dehydration there are relatively few reasons beyond severe dehydration for initiating IV therapy from the outset. A common misconception is that blood work is needed to assess dehydration, so placing the IV also allows blood to be obtained. However, both the American Academy of Pediatrics and the CDC have stated that there is no role for routine lab testing in typical mild to moderate dehydration so that, in combination with a trial of ORT, there is no reason for a child to get a needle stick at the outset. Most practitioners are very comfortable with the use of IV rehydration, but in practice IV fluids can be far from simple. Obtaining IV access can be a significant challenge in children. Studies suggest that multiple attempts are frequently needed, which take time and cause pain. Many children and families report that their most unpleasant experience of a hospital visit is IV placement. In some situations, other forms of access are utilized. The advent of devices that facilitate intraosseous (IO) access, a needle into the bone, have made this an option for first responders and emergency personnel who have difficulty obtaining IV access. IO access can be used for fluids and medications, but should be reserved for true emergency situations. Another less commonly used possibility for fluid replacement is subcutaneous (SQ) hydration which consists of placing a needle under the skin and putting fluid there. The fluid then gets absorbed into the blood vessels. It has the advantage of being very easy and fast to achieve. In conjunction with hyaluronidase, which facilitates fluid absorption in the SQ space, SQ hydration has been shown to be equal to IV hydration in terms of successful rehydration.
Parents should watch their children whenever their children are ill for signs of dehydration. Most illnesses cause children to lose their appetite so they need to be encouraged to keep up their fluid intake. Again, the specific fluid usually doesn’t matter as long as they can keep it down. The best treatment is to prevent dehydration from occurring. The seasonal flu vaccine is now available and all children under 5 are recommended to receive it as well as other high-risk groups. Another recent vaccine for children is to protect against Rotavirus which can cause severe diarrhea. You should call your doctor for advice if your child has decreased urination or is persistently vomiting and can’t hold anything down.
By Daniel Rauch, MD, Associate Professor of Pediatrics, Mount Sinai School of Medicine