Abstract 158: Ocular Near-Infrared Spectroscopy to Estimate Duration of Cardiac Arrest
BACKGROUND: The duration of cardiac arrest is associated with the likelihood of achieving intact neurological recovery and is often unknown. The use of Near-Infrared Spectroscopy (NIRS) allows for estimation of tissue oxygenation in the absence of pulsatile flow and may therefore provide improved estimation of tissue anoxia from cardiac arrest.
OBJECTIVE: The specific aim of this study was to determine if NIRS measurement of ocular tissue oxygenation (STO2) could estimate the duration of cardiac arrest.
METHODS: 30 Juvenile swine (~40 kg), in an ischemic model of cardiac arrest, had STO2 measured by NIRS probe over the contralateral eye to the carotid artery that was cannulated. STO2 recordings during spontaneous ventricular fibrillation without treatment for 7 minutes were aggregated to model the duration of cardiac arrest. Multivariate regression of blood gas analysis and the interval from coronary artery occlusion until arrest were performed to determine any associations.
RESULTS: There is a near immediate decline in STO2 with the initiation of cardiac arrest. The initial rate of decline is markedly different over the first 3 minutes and continues to incrementally decline as duration increases. The median STO2 at 7 minutes is 51% (IQR 45 - 54) with an average rate of change of -1.6% / min, whereas the median STO2 at 3 minutes was 58% (IQR 52-62) with an average rate of change of -3.0%/min. The average rate of change in the first minute is -11%/minute. Gasping during fibrillation was observed to increase STO2. There was no association with blood gases or duration of coronary artery occlusion with STO2.
CONCLUSION: Ocular STO2 is a viable option to monitor acute hemodynamic decline that is easily interpretable not requiring specific knowledge of ekg interpretation. The absolute value and rate of decline can provide a rough estimate of cardiac arrest duration greater than 3 minutes. Further study is needed to evaluate if specific outcomes are associated with these measures.
- © 2011 by American Heart Association, Inc.