This study aimed to quantify the degree of excessive ventilation during out-of-hospital cardiopulmonary resuscitation (CPR) and determine its impact on coronary perfusion pressure and survival rates in animals. In a clinical observational study, professional rescuers were found to hyperventilate patients at an average rate of 30 breaths per minute, significantly higher than the recommended 12-15 breaths per minute by the American Heart Association (AHA). No patients survived. In a subsequent animal study, pigs in cardiac arrest were ventilated at different rates (12, 20, and 30 breaths per minute) with 100% oxygen or a combination of 5% carbon dioxide and 95% oxygen. Results showed that higher ventilation rates led to significantly increased intrathoracic pressure and decreased coronary perfusion pressure, with survival rates being significantly lower at 30 breaths per minute (17%) compared to 12 breaths per minute (86%). The study concluded that excessive ventilation during CPR can have detrimental effects, including decreased coronary perfusion pressure and survival rates. It highlights the need for better education and training to reduce hyperventilation during CPR and improve outcomes.This study aimed to quantify the degree of excessive ventilation during out-of-hospital cardiopulmonary resuscitation (CPR) and determine its impact on coronary perfusion pressure and survival rates in animals. In a clinical observational study, professional rescuers were found to hyperventilate patients at an average rate of 30 breaths per minute, significantly higher than the recommended 12-15 breaths per minute by the American Heart Association (AHA). No patients survived. In a subsequent animal study, pigs in cardiac arrest were ventilated at different rates (12, 20, and 30 breaths per minute) with 100% oxygen or a combination of 5% carbon dioxide and 95% oxygen. Results showed that higher ventilation rates led to significantly increased intrathoracic pressure and decreased coronary perfusion pressure, with survival rates being significantly lower at 30 breaths per minute (17%) compared to 12 breaths per minute (86%). The study concluded that excessive ventilation during CPR can have detrimental effects, including decreased coronary perfusion pressure and survival rates. It highlights the need for better education and training to reduce hyperventilation during CPR and improve outcomes.