Experimental studies for safety on the operation of transverse aortic arch aneurysm. -A Study of Corticospinal Direct Response-

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The reconstruction of the transverse aortic arch is very complicated and spends a long time period, so it is essential to select the appropriate support technique to prevent cerebral ischemia. Recently it has been reported that profound hypothermic circulatory arrest(PHCA)or selective cerebral perfusion(SCP)are very useful as support procedure for preventing cerebral ischemia. However, PHCA is subject to limitations on the duration of cerebral circulatory arrest and a safe interval of circulatory arrest time has not been determined yet, and optimal selective cerebral perfusion flow and pressure in SCP is now discussing.And as for brain protection, it is also important to evaluate brain function during operation for preventing brain complication. The methods of the evaluation of brain function include the electrophysiological examinations such as corticospinal direct response(CDR), evoked spinal cord potential(ESCP)and somatosensory evoked potential(SEP).An experimental study was design … More ed to clarify the safety margins for cerebral circulatory arrest(CCA)under profound hypothermia by means of continuous measurement of evoked potential and histopathological studies of the brain and spinal cord tissues. Adult mongrel dogs were anesthetized with thlopental sodium and cooled to rectal temperature(RT)15 ﾟC with cardiopulmonary bypass and divided into 3 groups ; PHCA was performed for 30 minutes in Group I, 60 minutes in Group II, 90 minutes in Group III, and the next conclusion was gotten by CDR, ESCP and histopathological studies.1. PHCA at RT 15 ﾟC for at most 60 minutes would be safe for the preservation of brain function in view of CDR and a hypothermic preventive effect at the spinal cord could be maintained for 90 minutes or possibly longer at RT 15 ﾟC.2. CDR is a valid parameter for monitoring brain function in CPB.And in addition to this experiment we have been doing the experiment to decide optimal cerebral perfusion flow and pressure in SCP with monitoring brain function by CDR and SEP. Less