Question

A male patient weighing 68 kg is placed on heparin therapy for the prevention of deep vein thrombosis after surgery. DO NOT include units with your responses, these were provided.

• (a) How many milliliters (to nearest tenth) of a heparin injection containing 5000 units/mL should be administered for a loading dose of 80 units/kg?

• (b) What should be the infusion rate, in mL/hr (rounded to nearest tenth), using a solution that contains heparin 25,000 units/500 mL, to administer 18 units/kg/hr?

• (c) Six hours after heparin therapy is initiated, the patient's aPTT is found to be 75 seconds. Adjust the infusion rate, in mL/hr (rounded to a whole number), according to the adult weight based heparin protocol (see Fig. 10.1, text page 168).

Answer 1

a) How many milliliters (to nearest tenth) of a heparin injection containing 5000 units/mL should be administered for a loading dose of 80 units/kg?

Weight of the patient = 68kg

Available dose = 5000IU/ml

Ordered dose = 80units/kg  

= 80units 68kg

= 5440units

ml/dose= Ordered dose / available dose per ml

= 5440 / 5000

= 1.088ml

= 1.1ml

(b) What should be the infusion rate, in mL/hr (rounded to nearest tenth), using a solution that contains heparin 25,000 units/500 mL, to administer 18 units/kg/hr?

Weight of the patient = 68kg

Available dose = 25000units/500ml

Therefore, 1ml = 25000/500

1ml = 50units

Ordered dose = 18units/kg/hr

= 1868

= 1224units/hr

ml/hr = Ordered dose/ Available dose in 1ml

= 1224units/ 50units

= 24.48ml/hr

= 24.5ml/hr

(c) Six hours after heparin therapy is initiated, the patient's aPTT is found to be 75 seconds. Adjust the infusion rate, in mL/hr (rounded to a whole number), according to the adult weight based heparin protocol

According to the protocol, if aPTT after six hours of heparin therapy is 70-120seconds, then there is no need to change the dose. Continue with the same infusion for the next six hours and repeat aPTT there after.