Effect of Endotracheal Intubation and Supraglottic Airway Device Placement during Cardiopulmonary Resuscitation on Carotid Blood Flow over Resuscitation Time: An Experimental Porcine Cardiac Arrest Study.

Background: Supraglottic airway devices (SGDs) are widely used during the resuscitation of out-of-hospital cardiac arrest (OHCA). The effect of SGDs on carotid blood flow (CBF) as resuscitation time passes is controversial. We assessed the effects of endotracheal intubation (ETI) and 3 types of SGD placement on CBF over time in prolonged resuscitation through an experimental porcine cardiac arrest study. Methods: We conducted a randomized crossover study using 12 female pigs. After 4 min of untreated ventricular fibrillation, 3 pairs of ETI for 3 min and each type of SGD placement, including Combitube, I-gel, and laryngeal mask airway, for 3 min were conducted. The order of the 3 pairs of ETI and SGD were randomly assigned for each pig. We measured physiological parameters including CBF and mean arterial pressure (MAP). We compared CBF and MAP between the last 1 min of the insertion period for each of the 3 types of SGD and the preceding ETI period. Trends of CBF and MAP according to ETI and SGD transition were also plotted during the prolonged resuscitation duration. Results: CBF decreased after inserting I-gel and Combitube compared to ETI (mean difference (95% CI): -685 ml (-1052 to -318) for Combitube, -369 ml (-623 to -114) for I-gel). MAP subsequently decreased after transitioning airway devices as resuscitation was prolonged, regardless of the device type. The mean CBF during the transition from ETI to SGD decreased by -480 ml (95% CI: -675 to -286), but the decrease in CBF during the transition from SGD to ETI was only -4 ml (95% CI: -182 to 175). Conclusion: SGD placement was associated with decreased carotid blood flow during cardiopulmonary resuscitation in an experimental porcine model. As time passed during prolonged resuscitation, reduction in CBF was aggravated after the transition to SGD placement compared to the reduction after the transition to ETI. This study was approved by the study institution IACUC 16-0140-S1A0.