NORMOTHERMIC TECHNIQUE DURING OPEN HEART OPERATIONS

Abstract

Hypothermia was used to prolong safe period of ischaemic arrest by reducing oxygen demand, due to this effect: hypothermia has been considered to be the fundamental component of myocardial protection during cardiac surgery. Hypothermia has a number of deleterious and unwanted side effect such as: detrimental effects on enzyme function, energy generation, cell membrane. Na' pump inhibition and resultant edema, Ca" sequestration and the need for longer period of reperfusion to rewann the heart thereby increasing the potential of reperfusion injury4445 46)047,48,50 .51 Oxygen availability in blood cardioplegia is influenced by temperature because of lefttwad shift of the oxyhaemoglobin saturation curve in response to hypothermia Since electromechanical arrest diminishes oxygen requirements to near minimum (90%) with little further reduction is achieved by hypothermia; therefore if the arrested heart is perfused with oxygenated blood cardioplegia one can easily provides the remaining 10% of the requirements, under theis condition the need for hypothermia becomes questioned Under aerobic normothermic conditions the maximum number of adenosine triphosphates molecule produced by complete oxidation of one molecule of glucose is 36, while the number is roduced under .s anaerobic condition to only 2 molecules.