Coagulation, DVT, PE Flashcards
What is a pulmonary embolism?
PE blockage of an artery in the lungs by a substance arising from elsewhere, usually a venous thrombosis.
What are risk factors for pulmonary embolism?
Same as for DVT - age, recent surgery, thrombophilia, leg fracture, bed rest, malignancy, pregnancy, previous PE, oral contraceptive pill/ HRT; genetics [Lecture 10.1.18]
How are venous thrombi and arterial thrombi different?
Venous thrombosis is low-pressure, fibrin-rich and causes PE
Arterial thrombosis is high-pressure, platelet-rich and causes MI.
Why is proximal thrombosis more dangerous than distal thrombosis?
There is only one vein below the knee but 6 above the knee. Once they extend above the knee, they can cause PE. lecture 10.1.18
What is a compression test?
Can be done on knee, thigh or groin, and tests whether it can be compressed.
What does the D dimer test show?
It is an exclusion test - normal D dimer excludes thrombosis. D dimer is broken-down cross-linked fibrin, produced when there are clots. ALSO abnormal if pregnant, inflammation, malignancy, recent surgery.
What is INR?
International normalised ratio - a measurement of prothrombin time.
Describe the management of DVT and PE.
Distinguish cause - provoked thrombosis? Remove provoking factor. Spontaneous? Recurrence more likely, longer treatment.
LMW heparin
DOACs
Compression stocking for surgical patients
How can DVT and PE be prevented in hospital inpatients?
Once daily low dose LMW heparin SC injection - much less than for treatment
Early mobilisation
Elevate leg
What is a massive PE?
Blocks left and right pulmonary arteries. Cause of sudden death, often mistaken for an MI as cause of death in hospital.
What are the symptoms of PE?
Dyspnoea, pleuritic chest pain
What are the signs of PE?
Tachycardia, tachypnoea, pleural rub.
What investigation should you do for a suspected PE and why?
Excluding other causes:
D Dimer - normal excludes
ECG to exclude ACS. May see sinus tachycardia
CT pulmonary angiogram - spiral CT to visualise thrombi.
Blood gases show T1 resp failure.
What is thrombosis?
Blood coagulation inside an intact vessel of a living being.
How does warfarin work?
Prevents synthesis of active factors 2, 7, 9 and 10, and is an antagonist of vitamin K.