Impairment of Carotid Artery Blood Flow by Supraglottic Airway Use in a Swine Model of Cardiac Arrest
Nicolas Segal, Demetris Yannopoulos, Brian D. Mahoney, Ralph J. Frascone, Daniel Zarama, Scott H. McKnite, David G. Chase, University of Minnesota
Introduction. Supraglottic airway devices (SGDs) are often used as an alternative to endotracheal tubes (ETTs) during cardiopulmonary resuscitation (CPR). SGDs can be inserted “blindly” and rapidly, without stopping compressions. These devices utilize pressurized balloons to direct air to the trachea and prevent esophageal insufflation.
Objective. We hypothesized that the use of an SGD would compress the carotid artery and decrease carotid blood flow (CBF) during CPR in pigs.
Methods. Ventricular fibrillation was induced in nine female pigs (32 ± 1 kg) anesthetized with isoflurane followed by 4 minutes without compressions. CPR was then performed continuously for three 6-minute epochs. During each epoch, an ETT was used for the first 3 minutes, followed by 3 minutes of each SGD (King LTS-D, LMA Flexible, or Combitube) in a random order. The primary endpoint was mean CBF (mL/min). Statistical comparisons among the four airway devices were performed by Wilcoxon rank test. Postmortem carotid arteriographies were performed with the SGDs in place.
Results. CBF (mean mL/min ± standard deviation) was significantly lower with each SGD (King [168 ± 42], LMA [106 ± 89], and Combitube [99 ± 128]) versus ETT (209 ± 134) (p < 0.05 for each SGD compared with ETT). Arteriograms showed that with each SGD there was compression of the internal and external carotid vessels.
Conclusions. The use of three different SGDs during CPR significantly decreased CBF in a porcine model of cardiac arrest. While limited to pigs, these observations may impact management decisions related to the type and duration of SGD use in humans undergoing CPR.
