Stress response induced by cardiopulmonary bypass in fetal lambs submitted to ischemic preconditioning

• Grant number: 16/20810-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2017
• End date: January 31, 2018
• Field of knowledge: Health Sciences - Medicine - Surgery
• Principal Investigator: Renato Samy Assad
• Grantee: Marcelo Vaidotas Pinto
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

Cardiopulmonary bypass (CPB), required for the majority of open cardiac surgery, has direct and impactful relationship on an inappropriate endocrine-metabolic response. Previous studies have demonstrated a substantial increase in fetal plasma vasopressin during intrauterine hypoxia situations, with a consequent decrease in plasma oxygen and / or pH. In invasive procedures, the fetus can generate a metabolic stress response, releasing cortisol and beta-endorphin. However, the literature is still scarce concerning fetal CPB, an important mortality factor during and after the procedure, due to progressive respiratory acidosis. Remote ischemic preconditioning (rIPC) has been studied as a strategy to attenuate ischemia-reperfusion (IR) injury related to the effects of inflammatory mediators. The preconditioning stimulus has systemic effects to protect distant tissues during the surgical stress. This strategy may mitigate the metabolic response during the procedure. To assess placental function and stress hormones during CPB in fetuses submitted to rIPC, 18 fetal lambs will be randomly assigned to 3 groups (Negative Control, Sham and Preconditioned Group). rIPC will be induced by four 5-minutes cycles of hind limb ischemia, paired with 2-minutes of reperfusion, before establishment of CPB. Placental gas exchange and stress hormones will be assessed, aiming at attenuation of placental dysfunction and fetal metabolic response during CPB. (AU)