Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
Lovenox does last 12 hours. I'm not sure why you'd inject tomorrow for a trip that starts Saturday. You may want to call your doc's office to get clarification on the dosing and instructions, and if it's right, to explain what the thought process is. Six hours isn't that long if you stop ever couple of hours to get out, walk around, hydrate etc. So I can see not really need full on anticoagulation for that. But I just don't get the instructions to take your lovenox tomorrow. I mean, if the bulk of the driving is Saturday, why start it a day before that?