A client is prescribed heparin 20 units/kg/hr continuous IV infusion. The client weighs 150 lbs. Available: heparin 50 units/mL. How many mL/hr should the nurse administer via infusion pump?

Heparin is an anticoagulant preventing thromboembolism by accelerating antithrombin III. It is contraindicated in thrombocytopenia. Monitoring the activated partial thromboplastin time (aPTT) ensures a therapeutic range of 60 to 80 seconds. Rationale: A. 25.0 mL/hr is mathematically incorrect for a 68 kg patient receiving 20 units/kg/hr. This rate provides only 1250 units hourly, which is subtherapeutic for the weight. It fails to meet the ordered dose. Accuracy is vital. B. Step 1: Convert the client's weight from pounds (lbs) to kilograms (kg). The standard conversion factor is 1 kg = 2.2 lbs. Calculation: 150 lbs / 2.2 = 68.1818 kg. (Rounded to 68.2 kg for clinical precision). Step 2: Calculate the required units of heparin per hour (units/hr). The prescription is 20 units/kg/hr. Calculation: 68.1818 kg * 20 units/kg/hr = 1,363.636 units/hr. Step 3: Calculate the volume per hour (mL/hr) based on the available concentration. The concentration is 50 units/mL. Calculation: 1,363.636 units/hr / 50 units/mL = 27.2727 mL/hr. Step 4: Final Rounding. Following standard nursing math protocols for infusion pumps, the final rate is rounded to the nearest tenth. Result: 27.2 mL/hr. C. 30.0 mL/hr would deliver 1500 units of heparin per hour to the patient. This represents an overdose based on the weight parameters provided. Excess heparin increases the risk of spontaneous bleeding complications. It exceeds the prescription. D. A rate of 22.5 mL/hr delivers 1125 units per hour, which is too low. This subtherapeutic dosage fails to prevent thrombus formation in the patient. It does not meet the prescribed weight-based clinical requirements.