Effect of Airway Management and Impedance Threshold Device on Circulation, Survival and Neurological Outcome in Adult Out-Of-Hospital Cardiac Arrest

Abstract

Purpose: This study was designed to study the effect of early use of the King Airway (KA) and impedance threshold device (ITD) in out-of-hospital cardiac arrest on ETCO2 as a surrogate measure of circulation, survival, and cerebral performance category (CPC) scores. After analysis of the first 9 month active period the KA was relegated to rescue airway status. Methods: This was a prospective pre-post study design. Patients >18 years with out-of-hospital cardiac caused arrest were included. Three periods were compared. In the first “non active” period conventional AHA 30/2 compression/ventilation ratio CPR was done with bag mask ventilation (BMV). No ITD was used. After advanced airway placement the compression/ventilation ratio was 10/1. In the second period continuous compressions were done. Primary airway management was a KA with an ITD. After placement of the KA the compression/ventilation ratio was 10/1. In the third period CPR reverted to 30/2 ratio with a two hand seal BMV with ITD. CPR ratio was 10/1 post endotracheal intubation (ETI) or KA. The KA was only recommended for failed BMV and ETI. Results: Survival to hospital discharge was similar in all three study periods. In Period 2 there was a strong trend to CPC scores >2. The study group hypothesized that the KA interfered with cerebral blood flow. For that reason the KA was abandoned as a primary airway. Comparing Period 1 to Period 3 there was a trend to improved survival in the bystander witnessed shockable rhythm (Utstein) subgroup, particularly if a metronome was used. ETCO2 was significantly increased in Period 2 and trended up in Period 3 when compared to Period 1. Advanced airway intervention had a highly significant negative association with survival. Conclusion: The introduction of an ITD into our system did not result in a statistically significant improvement in survival. The study groups were somewhat dissimilar. ETCO2 trended up. When comparing Period 1 to Period 3, the bundle of care was associated with a trend towards increased survival in the Utstein subgroup, particularly with a metronome set at 100. Multiple confounders make a definitive conclusion impossible. Advanced airways showed a significant association with poor survival outcomes. The KA was additionally associated with poor neurologic outcomes.