SURGERY OF THE HEART:Surgery of heart usually involves opening the heart muscle.for operations of short duration it is possible to applay hypothermy (deep cooling) and thus temporarily stoping the blood circulations altogether however for major operations it is necessary to maintain the circulation by some other means of the dificulty of operating on the beating heart. this is achived by Cardiopulmonary bypass (CBP) technique, often the machiene have two fold function of mechanically pumping system and of enriching the low oxygen content blood comming from patient's body with fresh oxygen.
the venous blood,before it enters the right auricle of the heart, is diverted of vena cava and passed into plastic tubes. this blood which has already circulated through the body and concequently has a low oxygen content, is circulated through artificial lung. in a horizondal glass cylinder partly filled with blood number of steel discsrotate, which thus become wetted with blood.the blood on surface of these disks farms a thin flim of large area, which is exposed to stream of oxygene in the upper part of the glass cylinder.the red blood cells are thus able to absorb oxygen in much the same way in which they donthis in human lung.
A pump now passes theoxygene saturated blood through a heat controller and fillter then back to the patients arterial circulation. losses of blood occuring in the cource of the operations are compensated by a blood reservior. A second extracts venous blood from the heart ( the blood raching the heart through veins other than the vena cava ). this blood is defoamed and likewise passed to the artificial lung . before starting , the machine is filled with three or four litres of to which an anti-coagulant has been added so that it can not congeal.all the internal parts of the apparatus (except the steel dics) are ailicome treated to make them unwettable.
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nice.......................
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