Embodiments of the present invention include a system having at least one sensor configured to monitor a muscle oxygen saturation (SmO2) level of a patient who is undergoing cardiac arrest and to generate a signal representing SmO2 level； a user interface device； a processor communicably coupled to the user interface device, the processor configured to cause the user interface device to present an array of two or more possible nodes of a clinical decision support tree, wherein at least one of the nodes indicates cardiopulmonary resuscitation (CPR) treatment of the patient with no ventilation, and wherein at least another of the nodes indicates CPR treatment of the patient with active ventilation； determine which of the two or more possible nodes should be emphasized based on the SmO2 level； and update the array of the two or more possible nodes based on the determination.
