Effect of PEEP on Cardiac Output and Coronary Perfusion During CPR
The long-term objective of this study is to help improve survival in pediatric cardiac arrest patients by enhancing our understanding of CPR physiology. Given the fact that CPR provides only 15-20% of normal cardiac output, it is essential to recognize factors that can further impair the effectiveness of CPR in generating adequate cardiac output and coronary artery perfusion, thereby improving the chances of survival, including that of pediatric cardiac arrest patients. The specific aims of this study relate to understanding the effect of positive end expiratory pressure (PEEP) on cardiac output during CPR. PEEP is a pressure that is delivered during exhalation when one is receiving mechanical ventilation. Without PEEP, alveolar collapse can occur, which can have an adverse impact on both oxygenation as well as pulmonary blood flow. Through a complex series of cardio-pulmonary interactions, the right amount of PEEP can have a positive impact on both cardiac output and coronary artery perfusion pressure, the two most important factors in being able to achieve a return of spontaneous circulation following cardiac arrest. However, too much or too little PEEP can have a negative effect on both of these, thereby decreasing chances of a meaningful recovery following a cardiac arrest. Therefore, the first specific aim of this study will be to evaluate the effect of different levels of PEEP on cardiac output during CPR. The second specific aim of this study will be to evaluate the effect of PEEP on coronary perfusion pressure during CPR. This project aligns with the mission of the Nemours Research Lung Center, which is to improve pediatric care by enhancing research in pediatric pulmonary physiology. This study is designed as an animal study with a porcine cardiac arrest model using 20 kg Landrace-Yorkshire pigs. After anesthetizing the animals and placing appropriate vascular catheters, cardiac arrest will be induced using bupivacaine. CPR will be initiated using the LUCAS mechanical CPR compression device. The pigs will be ventilated during CPR with volume control ventilation and will be randomly placed on PEEP levels of 0, 5, 10, 15, and 20. After remaining on each PEEP level for 5 minutes, cardiac output will be measured with ultrasound dilution technology. Coronary perfusion pressure will be measured using the equation arterial diastolic pressure minus right atrial diastolic pressure. Through these methods, the appropriate amount of PEEP to maximize chances of survival following cardiac arrest will be determined.