Maintenance IV Fluids (4-2-1 Rule)
Calculates hourly maintenance IV fluid rate using the Holliday-Segar method based on body weight
- Highest activation tier
- Recommended
- How it is scored
- Scored in code; a stated value is compared only from the structured summary or a supplied value
- Scoring type
- formula
- Care settings
- ICU, Inpatient
When it activates
Scribeable activates a calculator from the encounter. The Maintenance IV Fluids (4-2-1 Rule) can activate when the transcript or pasted chart context documents any of these:
- NPO status requiring IV fluids
- Perioperative fluid management
- Pediatric fluid calculation
- Maintenance IV fluid initiation
- Dehydration fluid replacement planning
A coded diagnosis can also activate it. ICD-10 prefixes carried by the registry: E86, T73.1.
Inputs the note needs
1 input. Each is resolved from the transcript, the pasted chart context and charted labs; at this calculator’s tier a missing input is never requested, and a missing required input keeps the score out of the draft.
| Input | Type | Unit / options | Guidance |
|---|---|---|---|
| Body weight in kilograms | vital | kg |
Scoring
4 mL/kg/hr for first 10 kg + 2 mL/kg/hr for next 10 kg (11–20 kg) + 1 mL/kg/hr for each kg above 20 kg
4-2-1 rule over weight Body weight in kilograms kg: 4 mL/kg/h (first 10 kg) + 2 mL/kg/h (next 10 kg) + 1 mL/kg/h (each kg >20)
Interpretation
Example: 70 kg adult = 40 + 20 + 50 = 110 mL/hr. Daily requirement ≈ maintenance rate × 24 (e.g., ~2,640 mL/day for 70 kg). Adjust for fever (+10% per °C), losses, cardiac/renal status. Pediatric: use isotonic fluids (NS or LR) to prevent iatrogenic hyponatremia.
Evidence
Sources carried in Scribeable's citation registry for this calculator; guideline version: Holliday-Segar 1957.
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapyHolliday & Segar (4-2-1 Rule) 1957 · 1957 · link last verified 2026-03-28
How Scribeable handles it in the note
When an encounter activates the Maintenance IV Fluids (4-2-1 Rule) (its highest tier is recommended), Scribeable does not ask you for missing inputs. The score is computed in code from whatever inputs resolve from the transcript, the pasted chart context or charted labs; a computed value is written into the draft only when every required input already resolves.
The score is computed in code from the resolved inputs, not recalled by the language model. A stated Maintenance IV Fluids (4-2-1 Rule) value is compared against the computed one when the draft's structured summary carries it; a disagreement found there is flagged to the second drafting pass, which is instructed to correct the score and its interpretation, unless Scribeable has supplied the computed value to that pass, in which case the value the draft writes is checked against the supplied one and a detected difference is shown beside the note for you to adjudicate rather than silently rewritten.
Classified as a deterministic formula: a spare suggestion is easy to ignore, so activation is permissive.
See it activate on your own encounter
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