Dehydration is a shortage of water in the body and occurs when a person loses more fluid than they take in. It can result from a range of conditions (vomiting, diarrhoea, heat stress, fever, etc.), vigorous activity in hot and humid environments or when wearing excess clothing. These conditions cause a significant loss of water in the forms of sweat and other body fluids. They also cause the person to lose electrolytes, which are essential for the body to function normally. When the body is dehydrated, it can experience cramps, changes in mental capacity or even shock (which can be life-threatening if left untreated), especially in small children or older adults.
Guidelines
- First aid providers should motivate people with mild dehydration to drink enough fluids (e.g., water or diluted apple juice in children older than 6 months). **
- In more severe cases, first aid providers should rehydrate the person using either commercially prepared oral rehydration salts (ORS) or a pre-prepared salt package that complies with the World Health Organisation’s recommendations for ORS solutions. **
- First aid providers could use 3 to 8 percent carbohydrate-electrolyte drinks for exertion-related dehydration. If these are not available or not tolerated, alternative beverages include water, 12 percent carbohydrate-electrolyte solution, coconut water, two per cent milk, tea-based carbohydrate-electrolyte drinks or caffeinated tea.*
- Breastfeeding for babies should be continued. **
Good practice points
- Breastfed babies generally receive less milk each time they feed, and therefore require breastfeeding more frequently than bottle-fed babies.
- Bottle-fed babies should receive normal amounts of milk (powder dissolved in water, not in oral rehydration solution), supplemented with oral rehydration solution.
- Emergency medical services (EMS) should be accessed if the person’s responsiveness is altered (trouble waking up, confusion) or they become unresponsive.
- First aid providers should seek medical advice if they are in doubt, or if the person:
> is a baby, child or older adult
> loses more fluid than they take (e.g., severe vomiting)
> urinates very little or not at all and the urine has a dark colour
> has fever or signs of heat exhaustion. (See Hyperthermia.)
Chain of survival behaviours
Prevent and prepare
- In hot weather, regularly check on older adults and babies to ensure they remain cool and drink plenty of fluids.
- Ensure babies and young children continue to take breast or bottle milk (or other drinks) when they have fever or diarrhoea or are vomiting, as the risk of dehydration is high.
- Avoid doing any vigorous activity outside during the hottest part of the day.
- Train and acclimatise your body in the lead up to significant sports activity.
- In hot weather, dress appropriately, take frequent breaks in a shaded area, drink plenty of (cool) fluids and avoid activities that over-exert yourself.
- Carry plenty of fluids if travelling in remote areas with limited water supply.
- Practise good food and hand hygiene, and only consume potable (clean) water to avoid vomiting and diarrhoea (one of the main causes of dehydration).
Early recognition
The person may be in a hot environment, be doing vigorous physical activity during a heatwave, or may not have adequate access to fluids.
The person may have:
- diarrhoea or vomiting
- fever
- altered responsiveness
- headache
- dizziness
- less or no sweat (e.g. under the armpits)
- absence of tears
- dark coloured urine
- weak radial pulse
- dry mouth and tongue
- delayed time to skin re-colouration
- abnormal breathing pattern
- fatigue (in the elderly).
In babies and young children look for:
- dry mouth and tongue
- crying without tears
- sunken eyes
- unusually tired or sleepy
- a dry diaper for three hours or more.
First aid steps
- Reassure the person and give them plenty of fluids to drink.
a. In mild cases of dehydration, water is sufficient.
b. In more severe cases, give the person an oral rehydration solution. If this is unavailable, give the person apple juice, coconut water or water.
For children:
i. Babies and young children who are breastfed should continue to do so. The frequency of feeding should be increased.
ii. Babies receiving milk formula should drink regular amounts of milk, supplemented with oral rehydration solution. The formula should be dissolved in water, not in oral rehydration solution, as the latter may cause diarrhoea and worsen dehydration further.
iii. Children between the ages of 2 and 5 years should have 10 ml/kg (the caregiver will need to estimate their weight) of water, rehydration solution, apple juice, coconut water or water. - Seek medical advice if:
a. the person’s condition does not improve quickly
b. they are a baby, child or older adult
c. they are losing more fluid than they can take in (e.g., because of vomiting or diarrhoea)
d. they urinate very little or not at all and the urine has a dark colour
e. has fever or signs of heat exhaustion
f. you are in doubt.
_____________________________
NOTE
Oral rehydration recipe:
- Half a teaspoon of salt
- Six teaspoons of sugar
- One litre of drinking water
______________________________
Access help
- Access EMS if the person’s mental status changes (e.g., confusion) or they become unresponsive.
Self-recovery
- To avoid a case of new dehydration, continue to drink fluids regularly. Eat fruit and vegetables regularly.
Education considerations
Context considerations
- Depending on the availability and access to potable (clean) water, you may need to include information on water sterilisation methods (e.g., boiling or chlorination) and the risks of drinking contaminated water.
- Include information on the importance of drinking fluids which rehydrate the body, such as water and juice.
- Advocate for the use of breast milk for babies as a safe form of hydration which does not rely on potable (clean) water. If milk formula is the only available source of milk, emphasise the need for the water to be potable (clean) to avoid infections that cause vomiting and diarrhoea.
Learner considerations
- If facilitating a group of new parents, only include the content relevant to caring for a baby. Build learners’ confidence in their ability to identify potential causes of dehydration in babies (fever, vomiting, diarrhoea, overdressing, etc.) and their ability to prevent and recognise it.
- If facilitating a group of learners who have caring responsibilities for older people, discuss the risks of dehydration and ways to reduce the risks.
Facilitation tips and tools
- Ask learners to identify those most at risk of dehydration in their own lives and how to help to prevent it.
- Help learners recognise that dehydration can also occur in cold settings when people wear too many layers or overexert themselves.
- Provide learners with visual, written or verbal information about how to recognise dehydration.
- Recommend that learners prepare for dehydration by having access to drinking water, and store-bought or home-made ORS.
Learning connections
- Explore this topic alongside Abdominal pain, vomiting and diarrhoea or Hyperthermia and make connections to the leading causes of dehydration.
Scientific foundation
Systematic reviews
The following evidence was reviewed by the Centre for Evidence-Based Practice (CEBaP) in 2020. In addition, evidence from the International Liaison Committee on Resuscitation (ILCOR) about the use of carbohydrate-electrolyte solutions is also cited.
Signs or symptoms
In a diagnostic evidence summary from CEBaP, four systematic reviews were included.
There is limited evidence in favour of certain individual signs and symptoms to detect the presence or absence of dehydration. It was shown that fatigue in the elderly may be clinically helpful in the detection of the presence and absence of dehydration. Furthermore, it was shown that a prolonged capillary refill, weak radial pulse, absence of tears, dry oral mucous membrane, abnormal respiratory pattern, dark coloured urine, dry armpits, headache and dizziness may be helpful in the detection of the presence, but not the absence of dehydration.
In addition, it was shown that dry mucous membranes and sunken eyes may be clinically helpful in the detection of the absence, but not the presence of dehydration.
Finally, the clinical helpfulness of prolonged capillary refill, decreased skin elasticity, cold extremities, increased heart rate, poor overall appearance, absence of tears, dry mucous membranes, dry mouth, dry lips, being unable to spit, polypnea, sunken eyes, thirst and urine voiding frequency, to detect the presence or absence of dehydration, could not be demonstrated.
Evidence is of very low certainty and results cannot be considered precise due to low sample sizes, large variability in results and lack of data.
In addition, there is limited evidence in favour of using certain composite measures to detect the presence or absence of dehydration. It was shown that displaying at least three of the following clinical signs can be helpful in detecting the presence and absence of moderate (>5%) or severe (>10%) dehydration caused by acute diarrhoea:
- lack of tears
- sunken eyes
- dry mucous membranes
- poor overall appearance
- decreased skin elasticity
- deep and rapid breathing
- weak radial pulse.
Similarly, using the Gorelick scale (measuring lack of tears, dry mucous membranes, poor overall appearance and delayed time to skin-recolouration) can be helpful in detecting the presence and absence of moderate (>5%) or severe (>10%) dehydration.
On the other hand, the Clinical Dehydration scale (measuring general appearance, degree of sinking of the eyes, degree of dryness of the tongue, presence or absence of tears) can be clinically helpful to detect the presence, but not the absence, of severe (>6%) dehydration.
Furthermore, the clinical helpfulness of the WHO dehydration scale to detect moderate (5-10%) to severe (>10%) dehydration, and the clinical helpfulness of the Clinical Dehydration Scale or the Gorelick scale to detect moderate (3-6 % or >5 %) dehydration, could not be demonstrated.
Evidence is of very low certainty and results cannot be considered precise due to low sample sizes, large variability in results and lack of data.
Oral rehydration solution (commercial or home-made)
A 2016 evidence summary by CEBaP included one Cochrane systematic review. Since this review has been declared stable (new trials are unlikely to change its conclusions), this review and evidence summary have not been updated.
The 17 studies included in this Cochrane systematic review showed no difference between using an oral rehydration solution or intravenous therapy for treating dehydration due to gastroenteritis in children. Low-certainty evidence showed that oral rehydration therapy did not result in a statistically significant difference in weight gain, hyponatremia or hypernatremia, duration of diarrhoea or total fluid intake at 6 hours and 24 hours, compared to intravenous therapy. However, the use of oral rehydration therapy did result in a statistically significant decrease in length of hospital stay, but also resulted in a statistically significant failure to rehydrate, compared to intravenous therapy.
No studies were identified that compared the effectiveness of home-made (maize-based) oral rehydration solution to that of standard (reduced osmolarity) oral rehydration solution. However, one study was found about the feasibility of preparing maize and salt-based home-made oral rehydration solution compared to glucose-based oral rehydration solution. The study compared if oral rehydration solution compositions were within safe ranges, with sodium levels between 51-120 mmol. It was shown that making maize and salt oral rehydration solution resulted in a statistically significant decrease of making solutions with too high sodium levels (higher than 120 mmol/l), and a statistically significant increase in making solutions with a safe composition (sodium levels between 51-120 mmol/l), compared to making glucose-based oral rehydration solution. A statistically significant increase of oral rehydration solution with too low sodium levels (lower than 50 mmol/l), when making maize and salt oral rehydration solution compared to glucose oral rehydration solution, could not be demonstrated. Evidence is of low certainty and results cannot be considered precise due to the low number of events and/or large variability of results.
Apple juice
There is limited evidence from one randomised controlled trial in favour of using diluted apple juice and preferred fluids in children older than six months with mild gastroenteritis. It was shown that intake of diluted apple juice (half-strength), followed by intake of fluids of the child’s preference, resulted in a statistically significantly decreased risk of treatment failure and intravenous fluid requirement in low-risk children without signs of dehydration, compared to oral rehydration solution. A statistically significantly decreased risk of unscheduled healthcare visits, hospitalisation, extended symptoms and rate of vomiting or diarrhoea, when using diluted apple juice and preferred fluids, compared to oral rehydration solution, could not be demonstrated. Evidence is of moderate certainty.
In addition, there is limited evidence in favour of using ORS in addition to water. It was shown that intake of apple juice in addition to an ORS, resulted in a statistically significantly increased duration of diarrhoea and amount of stool loss in children with mild dehydration, compared to water in addition to oral rehydration solution. A statistically significant increase in body weight when using an oral rehydration solution and apple juice, compared to oral rehydration solution and water, could not be demonstrated. Evidence is of moderate certainty.
Breastfeeding
A 2020 evidence summary by CEBaP identified one randomised controlled trial and four case-control studies that provide limited evidence in favour of continuing breastfeeding in case of dehydration. Studies showed that stopping breastfeeding resulted in a statistically significant increased risk of dehydrating diarrhoea or increased risk of diarrhoea evolving to dehydration. Evidence is of very low certainty and results cannot be considered precise due to lack of data.
There is moderate-certainty evidence from one randomised controlled trial in favour of the combination of providing an oral rehydration solution and breastfeeding. This combination resulted in a statistically significant decrease in the number of times stools were passed in hospital and in the total volume of oral rehydration solution required for rehydration, compared to giving oral rehydration solution only. However, this study could not demonstrate a statistically significant decrease in stool output, vomitus volume and duration of diarrhoea when giving the combination of oral rehydration solution and breastfeeding.
Oral carbohydrate-electrolyte solutions
In 2015, ILCOR completed a systematic review on the use of carbohydrate-electrolyte solutions for people with exertion-related dehydration (Singletary, 2015 and Zideman, 2015). An update of this review is ongoing and will be available in the future. The review included 12 studies that showed that drinking 5% to 8% (8 studies) or 3% to 4% (3 studies) carbohydrate-electrolyte solutions facilitates rehydration after exercise-induced dehydration. Evidence also showed that participants generally tolerated ingesting these solutions. In the absence of shock, confusion, or inability to swallow, it was deemed reasonable for first aid providers to assist or encourage individuals with exertional dehydration to orally rehydrate with carbohydrate-electrolyte drinks. Other beverages such as a 12% carbohydrate-electrolyte solution (one study), coconut water (three studies), milk (one study), tea-based carbohydrate-electrolyte drinks (two studies) and Chinese tea with caffeine (one study), have also been found to promote rehydration after exercise-associated dehydration, but they may not be as readily available. Evidence is of low to very low certainty.
References
Systematic reviews
Centre for Evidence-Based Practice, Belgian Red Cross-Flanders. (2020). Evidence summary Dehydration – Apple juice. Available from:
https://www.cebap.org/knowledge-dissemination/first-aid-evidence-summaries/
Centre for Evidence-Based Practice, Belgian Red Cross-Flanders. (2020). Evidence summary Dehydration – Breastfeeding. Available from:
https://www.cebap.org/knowledge-dissemination/first-aid-evidence-summaries/
Centre for Evidence-Based Practice, Belgian Red Cross-Flanders. (2016). Evidence summaries to support First Aid Guidelines. Dehydration – ORS. Available from: https://www.cebap.org/knowledge-dissemination/first-aid-evidence-summaries/
Centre for Evidence-Based Practice, Belgian Red Cross-Flanders. (2020). Evidence summary Dehydration – Home-made ORS. Available from:
https://www.cebap.org/knowledge-dissemination/first-aid-evidence-summaries/
Centre for Evidence-Based Practice, Belgian Red Cross-Flanders. (2020). Evidence summary Dehydration – Signs and symptoms. Available from: https://www.cebap.org/knowledge-dissemination/first-aid-evidence-summaries/
Singletary, E. M., Zideman, D. A., De Buck, E. D., Chang, W. T., Jensen, J. L., Swain, J. M., … & Hood, N. A. (2015). Part 9: First aid: 2015 International consensus on first aid science with treatment recommendations. Circulation, 132(16_suppl_1), S269-S311. DOI 10.1161/CIR.0000000000000278
Zideman, D.A, Singletary, E.M., De Buck, E., Chang, W.T., Jensen, J.L., Swain, J.M., … & Yang, H.J. (2015). Part 9: First aid: 2015 International consensus on first aid science with treatment recommendations. Resuscitation. 95. e225-e261. DOI 10.1016/j.resuscitation.2015.07.047
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