Anticoagulation with intravenous heparin was started immediately with target PTT of 50 65 seconds. On the evening of the next day, Robert became acutely unresponsive with no speech, eye opening ...

We realized that the re-agents our lab uses to determine PTT values vary on a yearly basis (when reordered) such that our normal range values also differ on a yearly basis. Our heparin order form ...