Brain Death/diagnosis; Critical Care/organization & administration; Life Support Care/organization & administration; Tissue Donors; Tissue and Organ Procurement/organization & administration; Advance Directives/ethics; Advance Directives/legislation & jurisprudence; Aged; Brain Death/legislation & jurisprudence; Brain Death/physiopathology; Clinical Protocols; Communication; Critical Care/ethics; Critical Care/psychology; Family/psychology; Female; Humans; Life Support Care/ethics; Magnetic Resonance Imaging; Nurse Clinicians/ethics; Nurse Clinicians/organization & administration; Nurse's Role; Nursing Assessment; Patient Advocacy/ethics; Patient Advocacy/legislation & jurisprudence; Professional-Family Relations/ethics; Resuscitation/ethics; Resuscitation/methods; Tissue Donors/ethics; Tissue Donors/legislation & jurisprudence; Tissue and Organ Procurement/ethics; Tomography, X-Ray Computed