Use of the trendelenburg position in the porcine model improves carotid flow during cardiopulmonary resuscitation

Cardiopulmonary resuscitation (CPR) is now widely used as a treatment for ventricular fibrillation, though numerous studies have shown the outcome of standard CPR to be dismal. Alternative methods of CPR, including interposed abdominal compression, constant aortic occlusion, and the use of intrathoracic pressure regulator, have been shown to increase cardiac output and affect the mortality rate of CPR. Here we suggest the Trendelenburg position as yet another method of increasing cardiac output and therefore improving the effectiveness of chest compressions. We hypothesized that the use of the Trendelenburg position during CPR would increase cardiac output as measured by carotid blood flow. We anaesthetized six pigs and measured their pre-arrest carotid flow rate for two minutes. We then induced ventricular fibrillation in those pigs and performed open-chest CPR on them. Post-arrest carotid blood flow was measured for two minutes each at 0 (supine position), 10, 20, and 30 degrees of head-down tilt in each pig. The mean carotid flow for each degree of tilt was compared to mean carotid flow at 0 degrees of tilt using a paired student t-test. We found an increase of up to 1.4-fold in carotid blood flow during CPR in the Trendelenburg position, though only 20 and 30 degrees of Trendelenburg showed a statistically significant increase from the 0 degrees of tilt in pigs. The Trendelenburg position can lead to increased blood flow through the carotid arteries during CPR in this pig model. Future studies should investigate whether this increased blood flow through the carotid arteries leads to improved brain perfusion and better neurologic outcomes.