The patients' safety is paramount and if there is any doubt about patient blood pressure monitoring the safest course of action is to return to CPB. No measured parameters should be disregarded without concrete evidence to the contrary or without consulting the multi-disciplinary team. At key events during any procedure such as application or removal of clamps there should be a check and cross-check communication verification between team members. Standard Operating Procedures for the various phases of CPB should be implemented and if necessary specific checklists should be used.