INTRODUCTION: High-quality ventilation in unconscious victims is a priority action for first responders at the scene. Firefighters often arrive first at the scene, providing medical assistance at the level of qualified first aid (QFA). This research aimed to evaluate the quality of ventilation using supraglottic methods with and without visual feedback and self-inflating bags during simulated cardiopulmonary resuscitation (CPR) performed by members of the State Fire Service (SFS). MATERIAL AND METHODS: A cross-sectional study was conducted in organizational units of the State Fire Service (SFS) in the Lubelskie and Warmińsko-Mazurskie voivodeships (24-hour duty officers). 112 firefighters aged 26–48 years (Mean 33.1; SD 6.7), with service duration of 1-20 years (Mean 7.3; SD 4.7) participated in the study. The study involved a 2-minute supraglottic ventilation (self-expanding bag + I-gel mask, size 4: 50–90 kg). Subsequently, 2-minute ventilation was conducted with the effectiveness visible on the monitor in real-time. The following ventilation variables were recorded: frequency (per minute), the volume of each inhalation (mL), and the ratio of correct to incorrect single inhalations (%). RESULTS: It was shown that in stage 1, firefighters more often (P < 0.001) performed ventilation at an excessively high frequency (max rate = 14 ± 4) compared to stage 2 (max rate = 11 ± 1). A statistically significant influence of the possibility of assessment and correction of rescue actions in real-time on the correct frequency (% correct – rate = 52.3 ± 30.1 vs 91.4 ± 12.1; P < 0.001) and ventilation volume (% correct — V = 40.6 ± 28.2 vs 85.3 ± 15.0; P < 0.001) was demonstrated. No statistically significant impact of service duration and age on evaluating parameters in stages 1 and 2 was shown. CONCLUSIONS: Software assistance and the possibility of real-time feedback significantly improve the quality of ventilation conducted by firefighters using SAD. More training using elements of medical simulation with visual feedback should be introduced so that firefighters improve ventilation quality under realistic conditions. Consideration should be given to including tools for assessing CPR quality in CPR rescue kits, especially in units that, according to statistics, handle a larger number of EMS interventions.