A medical system, comprising: a manual patient ventilation unit defining an airflow path, the unit arranged so that when the unit is applied to a patient, the airflow path is in fluid communication with the patient's airway, the patient ventilation unit comprising a ventilation bag (104, 712) configured to enable manual ventilation of the patient by a rescuer; and at least one sensor (106, 204, 718, 722) in the airflow path positioned to sense the presence of ventilation airflow and measure a gas flow rate in the airflow path and sense gas pressure in the airflow path; a processor; and a feedback unit; characterized by a chest compression sensor configured to detect and measure a quality of chest compressions; and in that said processor is arranged to: wirelessly receive data generated by the at least one sensor (106, 204, 718, 722) and determine one or more ventilation quality parameters based at least in part on a gas flow volume calculated based on the sensed gas flow rate and gas pressures, and receive data generated by the chest compression sensor; and said feedback unit being arranged to: provide chest compression feedback to a rescuer, the chest compression feedback comprising information about performance of the chest compressions; and provide ventilation feedback to the rescuer, the ventilation feedback comprising the one or more ventilation quality parameters. a manual patient ventilation unit defining an airflow path, the unit arranged so that when the unit is applied to a patient, the airflow path is in fluid communication with the patient's airway, the patient ventilation unit comprising a ventilation bag (104, 712) configured to enable manual ventilation of the patient by a rescuer; and at least one sensor (106, 204, 718, 722) in the airflow path positioned to sense the presence of ventilation airflow and measure a gas flow rate in the airflow path and sense gas pressure in the airflow path; a ventilation bag (104, 712) configured to enable manual ventilation of the patient by a rescuer; and at least one sensor (106, 204, 718, 722) in the airflow path positioned to sense the presence of ventilation airflow and measure a gas flow rate in the airflow path and sense gas pressure in the airflow path; a processor; and a feedback unit; characterized by a chest compression sensor configured to detect and measure a quality of chest compressions; and in that said processor is arranged to: wirelessly receive data generated by the at least one sensor (106, 204, 718, 722) and determine one or more ventilation quality parameters based at least in part on a gas flow volume calculated based on the sensed gas flow rate and gas pressures, and receive data generated by the chest compression sensor; and said feedback unit being arranged to: provide chest compression feedback to a rescuer, the chest compression feedback comprising information about performance of the chest compressions; and provide ventilation feedback to the rescuer, the ventilation feedback comprising the one or more ventilation quality parameters. wirelessly receive data generated by the at least one sensor (106, 204, 718, 722) and determine one or more ventilation quality parameters based at least in part on a gas flow volume calculated based on the sensed gas flow rate and gas pressures, and receive data generated by the chest compression sensor; and said feedback unit being arranged to: provide chest compression feedback to a rescuer, the chest compression feedback comprising information about performance of the chest compressions; and provide ventilation feedback to the rescuer, the ventilation feedback comprising the one or more ventilation quality parameters. provide chest compression feedback to a rescuer, the chest compression feedback comprising information about performance of the chest compressions; and provide ventilation feedback to the rescuer, the ventilation feedback comprising the one or more ventilation quality parameters.