Dehydration is a physiologic response to a variety of diseases and conditions that results in a negative fluid balance due to decreased intake; increased output via renal, gastrointestinal, or insensible losses; or a systemic response to the specific disease state (eg, burns or sepsis). Dehydration causes total body water and electrolyte losses in the intracellular fluid (ICF) and extracellular fluid (ECF) compartments and can range from asymptomatic or mild to severe, with or without hypovolemic shock. As a result, a spectrum of signs and symptoms is seen.
During a busy shift in the emergency department, you obtain a history and perform a physical examination on a 3-month-old male patient. The mother states that her son has become progressively more listless over the past 3 days, has been drinking less than normal, and has only urinated once in the previous 12 hours. She also notes that the patient has had "tremors intermittently all day." In addition, he has had 3 episodes of vomiting without blood or bile and has a slight runny nose but no fever, diarrhea, or ill contacts.
The physical examination reveals a temperature of 37.9ºC (100.2ºF), a resting heart rate of 186 beats per minute, a respiratory rate of 56 breaths per minute, and a blood pressure reading of 78/50 mm Hg. The patient is visibly listless and has intermittent, erratic jerking in his arms and legs as well as a slightly sunken fontanel, no visible tears, and dry, sticky mucous membranes. Findings from an examination of his lungs, heart, and abdomen are normal, and further examination demonstrates slightly cool distal extremities, with a capillary refill time of 3 seconds.
This patient is clearly dehydrated, although the etiology of his signs and symptoms is unclear. As you evaluate the patient, you think about the following issues:
The literature utilized for this article came from Ovid MEDLINE and PubMed searches using the key terms: pediatric, dehydration, assessment, clinical signs, symptoms, and treatment from 1990-2009. The article will focus on dehydration controversies in several areas, including the assessment of levels or severity of dehydration, the sensitivities of clinical signs and symptoms, and the utility of laboratory investigations.
Evidence-based medicine requires a critical appraisal of the literature based upon study methodology and number of subjects. Not all references are equally robust. The findings of a large, prospective, randomized, and blinded trial should carry more weight than a case report.
To help the reader judge the strength of each reference, pertinent information about the study, such as the type of study and the number of patients in the study, will be included in bold type following the reference, where available. In addition, the most informative references cited in this paper, as determined by the authors, will be noted by an asterisk (*) next to the number of the reference.