Another risk factor that must be highlighted is ineffective tissue perfusion. According to a study conducted by Gordon and Hiltunen (1995), ineffective tissue perfusion is considered a frequent and priority diagnosis by 88% of experts, along with DCO, which was mentioned by 91% of the experts. Approximate prevalence was reported by Galdeano et al. (2004) in 70·6% of patients during the pre-operative period of cardiac surgery. Additionally, Santos (2006)supported the use of this factor, pointing out ineffective cardiac tissue perfusion as a clinical indicator present in her research.