Out-of-hospital cardiac arrest (OHCA), a sudden cessation of heart activity occurring outside the hospital and resulting in loss of blood circulation, remains a major public health concern in Europe, affecting approximately 1 in 1,000 people annually. Despite advances in emergency care, survival rates remain low, with only 8% to 12% of patients surviving to hospital discharge. Early recognition and start of cardiopulmonary resuscitation (CPR) are critical to improve survival. CPR involves chest compressions and, if trained, rescue breaths to keep blood and oxygen flowing to the brain and other vital organs. High-quality chest compressions are strongly linked to better survival outcomes. However, even trained professionals can make errors during manual compressions, such as leaning or incorrect depth or rate and interruptions and can experience fatigue. To address these challenges, mechanical CPR devices have been developed. These machines deliver compressions at a consistent depth, rate, and force. However, research so far has not shown better clinical outcomes with mechanical devices compared to manual CPR. As a result, current guidelines recommend their use only in specific situations where manual CPR is impractical or unsafe. To better understand the physiological effects of these devices, this study at Ghent University Hospital investigated how mechanical CPR affects airway pressure — a key factor in both blood and airflow during resuscitation. We compared patients who received manual compressions with those treated using a mechanical device. The results showed only slightly higher airway pressures in the mechanical group. Other factors such as breathing rate, compression depth, and survival were also similar between the two groups. Among survivors, airway pressures were again slightly higher, but not significantly enough to draw firm conclusions. Importantly, this was the first study to calculate the mean airway pressure during real-life CPR in the prehospital setting — before patients arrive at the hospital. The findings highlight the complexity of CPR, especially the interaction between compressions and ventilations, and show that there is still much to learn. A deeper understanding of how different CPR methods affect the body could lead to improved techniques, better device design, and ultimately, better outcomes for patients experiencing cardiac arrest.