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Questions and Answers
What is the main reason why children require a greater daily fluid intake compared to adults?
In severe dehydration, which vital sign abnormality would most likely be observed?
During hospital admission, which of the following is considered an ongoing loss of fluids?
What is the recommended fluid replacement approach for a patient with severe dehydration (shock)?
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How is the amount of deficit fluid calculated for a patient with 3% dehydration who weighs 60 kg?
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How is the total fluid requirement for a 70 kg patient with 5% dehydration calculated?
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In the Holliday-Segar method, which rule is used to calculate the daily fluid need?
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How much fluid should be replaced for every degree of fever above 37.5°C?
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What is the hourly fluid requirement for the first 10kg of a patient according to the Holliday-Segar method?
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How should ongoing fluid loss replacement be managed?
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Study Notes
Body Composition and Fluid Requirements
- 60% of body weight is water, with 2/3 being intracellular (IC) mainly in muscle and 1/3 being extracellular (EC)
- 75% of EC fluid is in interstitial fluid and 25% is in plasma
- Newborns have 80% of their body weight as water, which is less in females and obese individuals
Daily Fluid Requirements
- Adults require approximately 35cc/kg/day of fluid
- Children require more fluid due to: • Larger surface area in relation to body mass, leading to more loss • Greater need for metabolic activity due to growth • Poor concentrating ability of the immature kidney, leading to more loss
Types of Fluid Loss
- Deficit loss: Amount of fluid lost at time of presentation, calculated based on weight and degree of dehydration
- Maintenance fluid: Amount of fluid needed for daily metabolic activities, calculated based on weight regardless of dehydration
- Ongoing loss: Losses that occur during hospital admission, such as through Foley's catheter, NGT, drains, bleeding, fever, and ventilation
- Third space loss: Losses that occur during surgery, depending on the type of operation
Dehydration Classification
- Mild dehydration: 3-5% of total body weight (TBW) lost
- Moderate dehydration: 6-9% of TBW lost
- Severe dehydration: 10-15% of TBW lost
Clinical Signs of Dehydration
- Mild dehydration: Thirst, dry gray skin, capillary refill in 2-4 seconds, dry mouth, and absent tears
- Moderate dehydration: Thirst, pale skin, capillary refill in less than 2 seconds, dry mouth, and absent tears
- Severe dehydration: Extreme thirst, dry mottled skin, capillary refill in more than 4 seconds, very dry mouth, sunken eyes, and no urine output
Calculating Deficits
- Formula: Weight in grams x percentage of dehydration
- Example: 70 kg patient with 5% dehydration = 3500 mL deficit
Replacing Deficits
- Replace 50% of deficit in the first 8 hours and 50% in the next 16 hours
- For severe dehydration, give a rapid bolus of 500 mL of 0.9% NaCl over less than 15 minutes, repeated until vital signs stabilize
Calculating Maintenance Fluid
- Alternative Holliday-Segar method: • 4-2-1 rule for hourly need: 4 mL/kg for the first 10 kg, 2 mL/kg for the next 10 kg, and 1 mL/kg for the remaining kg • 100-50-20 rule for daily need: 100 mL/kg for the first 10 kg, 50 mL/kg for the next 10 kg, and 20 mL/kg for the remaining kg
Ongoing Loss Replacement
- Replace fluid loss with the same amount of intravenous fluid
- Each cc of blood loss is replaced by 1 cc of blood or 3cc of crystalloids
- Replace 100-150 mL/day for every degree of fever above 37.5°C
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Description
Learn about the calculation of deficit and maintenance fluid in various clinical scenarios. This quiz covers topics such as body water distribution, daily fluid requirements for adults and children, and factors affecting fluid needs.
