From the Guidelines
The criteria for assessing dehydration in Australia focus on clinical signs and symptoms rather than a single diagnostic test, with an emphasis on evaluating multiple parameters including skin turgor, mucous membrane moisture, capillary refill time, heart rate, blood pressure, urine output, and mental status, as recommended by the most recent guidelines 1. Dehydration assessment typically involves evaluating these parameters to determine the severity of dehydration.
- In mild dehydration (less than 5% fluid loss), patients may present with dry mucous membranes, slightly decreased skin turgor, and thirst.
- Moderate dehydration (5-10% fluid loss) often manifests as tachycardia, hypotension, reduced urine output, sunken eyes, and delayed capillary refill (greater than 2 seconds).
- Severe dehydration (over 10% fluid loss) presents with significantly decreased blood pressure, rapid weak pulse, minimal or no urine output, severely decreased skin turgor, and altered consciousness. Laboratory tests including serum electrolytes, blood urea nitrogen, creatinine, and urine specific gravity can provide supporting evidence but are not required for initial assessment, as stated in the guidelines 1. These criteria are particularly important in vulnerable populations such as infants, elderly people, and those with chronic illnesses, where dehydration can rapidly become life-threatening, and early recognition using these clinical signs allows for prompt rehydration therapy, which typically begins with oral rehydration solutions for mild cases and may progress to intravenous fluids for moderate to severe cases, as recommended by the most recent and highest quality study 1. The use of hypotonic fluids is recommended for treating low-intake dehydration in older persons, and oral rehydration therapy and sports drinks are not indicated in this population, as stated in the guidelines 1. The most recent and highest quality study 1 provides the best evidence for assessing dehydration in Australia, and its recommendations should be followed in clinical practice.
From the Research
Criteria for Assessing Dehydration in Australia
The criteria for assessing dehydration in Australia are not explicitly stated in the provided studies, but we can look at the general criteria used in various studies to assess dehydration.
- Clinical observations based on a combination of history, physical examination, laboratory values, and clinician experience remain the best approach to the diagnosis of dehydration 2.
- Clinical signs such as tear production, palpitating pressure, thirst, and mucous wetness can provide important information for diagnosing dehydration 2.
- Laboratory values such as osmolality, blood urea nitrogen/creatinine, and specific gravity can also be used to assess dehydration 2, 3.
- A scoring system such as the Novel, Innovative Research for Understanding Dehydration in Adults and Kids (NIRUDAK) Score, which includes age, sex, sunken eyes, radial pulse, respiration depth, skin turgor, and vomiting episodes in 24 hours, can be used to predict dehydration severity 4.
- Other criteria such as serum osmolality, serum sodium concentration, inferior vena cava ultrasonography, a history of not drinking between meals, and axillary dryness have been found to have high diagnostic value for assessing hydration status in older patients 5.
Limitations of Current Criteria
- There is no single, universal gold standard for decision making in assessing dehydration 2, 3.
- Clinical signs and symptoms can be of variable or poor diagnostic value, especially in older patients 6, 5.
- Laboratory values can also be affected by various factors, such as the type and magnitude of dehydration 3.