Math
Historical Parkland and 4-2-1 formulas as spreadsheet arithmetic exercises
Practice multiplication, remaining-volume arithmetic and piecewise weight brackets using fictional inputs, not clinical dosing instructions.
Historical formulas, not an infusion prescription
The4mL/kg/%TBSA Parkland expression is shown as a historical arithmetic model, not a current universal prescription. Contemporary burn guidance uses different starting approaches and requires clinical reassessment. The cells do not determine fluid type, eligibility, titration or safe infusion rates. Do not use this exercise for patient care.
TBSA is entered in percentage points, such as20 for20%, and need not be an integer. The first historical interval is measured from injury. Remaining-volume arithmetic must account for fluid already given: B6 records that amount. Dividing a remaining amount by remaining hours is only arithmetic, not an instruction to catch up or adjust a pump.
The4-2-1 hourly rule is an approximation distinct from the100/50/20mL/kg/day Holliday–Segar calculation divided by24. For25kg these give65 and66.67mL/hour respectively. They are not interchangeable prescriptions; age, clinical state and monitoring are outside this example.
| Historical arithmetic | Fictional input | Calculation | Numerical result |
|---|---|---|---|
| Parkland 24h Total (75 kg, 20%) | B2 = 75 kg, B3 = 20 (%TBSA) | 4 * 75 * 20 | 6000mL modeled total |
| First-8h Rate (0h delay, B4 = 8) | (6000 / 2) / 8 hrs | 3,000 / 8 | 375 mL/hr (Next 16h = 187.5 mL/hr) |
| Six hours remaining, none recorded given | 3,000 / 6 remaining hrs | Arithmetic quotient only | 500mL/hour, not a pump instruction |
| Holliday-Segar 4-2-1 (B5 = 25 kg) | 10*4 + 10*2 + 5*1 | 40 + 20 + 5 | 65 mL/hr maintenance |
Remaining historical first-interval volume divided by hours
Subtract B6 from the modeled first-half total before dividing by B4. Reject zero or more than8 remaining hours, negative delivered volume, or delivered volume exceeding that modeled half. A rejected input calls for review, not an automatically revised rate.
=IF(OR(COUNT(B2:B4)<>3,COUNT(B6)<>1,B2<=0,B3<=0,B3>100,B4<=0,B4>8,B6<0,B6>2*B2*B3),"Invalid inputs",ROUND((2*B2*B3-B6)/B4,2))Piecewise4-2-1 arithmetic
MIN and MAX allocate positive weight across the first10kg, next10kg and remainder. This example verifies bracket arithmetic, not suitability for infants or ill children.
=IF(OR(COUNT(B5)<>1,B5<=0),"Invalid inputs",ROUND(MIN(B5, 10) * 4 + MAX(0, MIN(B5 - 10, 10)) * 2 + MAX(0, B5 - 20) * 1, 2))Try the example
Use the original values or change them to test your understanding.