Objective: Supraglottic airway devices (SGDs) can be inserted ‘blindly’ without stopping compressions during cardiopulmonary resuscitation (CPR) and are therefore often used instead of endotracheal tubes (ETT). These devices utilize pressurized balloons to direct air to the trachea and prevent esophagus insufflation. We hypothesize that the use of a SGD will compress the carotid artery and decrease carotid blood flow (CBF) during CPR.
Methods: Ventricular fibrillation was induced in 9 female pigs (32±1Kg) anesthetized with isoflurane. Four minutes later CPR was then performed continuously for 3 six-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 4 airway devices were performed by Wilcoxon Rank test. Post mortem carotid arteriograms were obtained.
Results: CBF (mean ml/minute ± SD) 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; figure). Arteriograms showed that each SGD compressed the internal and external carotid vessels.
Conclusion: The use of 3 different SGDs during CPR significantly decreased CBF in a porcine cardiac arrest model. While these data are limited to pigs, they may impact clinical decision making. Figure: real time tracing during 1 experiment. Pink: Carotid blood flow (CBF); Blue: Thoracic aortic pressure (AO pressure); Green: Airway pressure. The figure shows that every time a SGD is used CBF significantly decreases without any differences in AO pressure