farnsworth
Forum Newbie
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After initialization of IABP, heparin therapy is started, to prevent clot formation (the surface of the balloon can be thrombogenic). Some authorities recommend a PTT of 4x the upper normal limit, some people recommend low dose heparin with aiming at a PTT of 35-40 secs, as some studies show a decrease of bleeding complications with this approach. Anyway, the risk of clot formation is increased with foreign materials in someones body.
The rationale to check the lower limbs for thrombosis/ischemia: the IABP has a diameter of 8 or 9.5F, the balloon contains 40mL of helium during inflation! It is usually inserted via the left or right femoral artery into the descending aorta, the distal end of the balloon should be just below (2cm) the point where the left subclavian artery branches from the aorta. So also the pulse on the left upper extremity should be checked (for convenience stick the fingerclip of the pulse oximeter on one of the fingers of the left hand). The proximal end of the balloon should be above the part of the abdominal aorta, where renal arteries branch off.
Common contraindications:
Aneurysm of the abdominal/thoracic aorta
severe peripheral vascular disease
vascular prosthesis in the femoral artery
severe aortic valve insufficiency (this becomes clear if you image the way the IABP works: in deflates during systole, to let the blood ejected from the left ventricle pass the balloon to the periphery. The quick deflation leads to an immediate afterload reduction for the left ventricle. During diastole the balloon is inflated and blood is 'pressed' to parts of the aorta above and below the balloon, depending mostly on systemic vascular resistance, SVR. So the diastolic blood pressure in the thoracic part of the aorta increases, the coronary artery perfusion increases, too, as long as the aortic valve is closed. A severe aortic valve insufficiency leads to a 'backflow' of blood into the left ventricle, distending the already compromised ventricle even more, the transmural wall pressure increases, the coronary perfusion pressure decreases -> bad thing!).
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| docnikki
Forum Guru
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Posts: 680
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thanks sooo much dear  )
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