Unfolding case: a heparin drip from order to titration
A six-column titration table across four rows showing time, result against band in words only, protocol action, units per kilogram per hour, units per hour and mL/hr, with the one row where the rate changes flagged by a strip breaking the left edge.
The case
A post-operative adult is admitted for suspected venous thromboembolism. Charted weight: 220 lb. Protocol: a bolus of 80 units/kg, then a continuous infusion at 18 units/kg/hr. Infusion bag: heparin 25,000 units in 250 mL. Bolus supply: 5000 units/mL. Six hours after initiation, the coagulation result returns below the protocol's therapeutic band.
CUE — What are the three numbers that drive everything, and are they in the right units?
220 lb × (1 kg / 2.2 lb) = 100 kg 25,000 units ÷ 250 mL = 100 units/mL The third number is the bolus supply, 5000 units/mL, and it is already usable.
ANALYZE — Are the bolus and the infusion the same problem?
No. Two independent quantities are being asked for: a one-time bolus expressed in units, and a continuous rate expressed in mL/hr. They come from different supplies at different concentrations and must never be computed from the same vial.
PRIORITIZE — Which is computed first, and why compute both before giving either?
The bolus is the immediate action; the drip is the sustaining one. Compute both before touching either, because the bolus dose is also the check on whether the weight is right. A weight error shows up in both numbers at once.
GENERATE SOLUTIONS — What are the two numbers?
Bolus: 100 kg × 80 units/kg = 8000 units 8000 units × (1 mL / 5000 units) = 1.6 mL Infusion: 100 kg × 18 units/kg/hr = 1800 units/hr 1800 units/hr × (1 mL / 100 units) = 18 mL/hr
TAKE ACTION — What happens before the drug moves?
An independent double check by a second nurse before the bolus and before the pump starts, per high-alert protocol. Program the rate in mL/hr and set the dose guard in units per hour, so the pump is checking both expressions of the same order.
EVALUATE — The result returns below band. What is the new rate?
Protocol directs an increase of 2 units/kg/hr. 100 kg × 2 units/kg/hr = 200 units/hr added. New rate: 1800 + 200 = 2000 units/hr 2000 units/hr × (1 mL / 100 units) = 20 mL/hr Recheck at the protocol interval.
Protocol note: many protocols cap the dosing weight used for heparin, so the weight you calculate from is not always the weight on the scale. The protocol governs.
Watch outINDEPENDENT DOUBLE CHECK. Same patient, two supplies. Do not mix them up.
Margin notethe coagulation band itself is not printed in this book. → BOOK 07 · P6
Takeawayone weight and one concentration, and every number on the pump falls out of them.