ARVO Annual Meeting Abstract | September 2016
Retinal blood flow (RBF) may offer insights into systemic health, providing physiological markers for disease and recovery. Researchers may benefit from the ability to simultaneously monitor RBF and other functional data such as systemic blood pressure (BP), electrocardiogram (ECG) and electroencephalogram (EEG) readings, and cerebral blood flow (CBF). The purpose of this study was to develop novel instrumentation for multi-parameter functional data and demonstrate feasibility by characterizing changes that accompany cardiac arrest, resuscitation and recovery.
A modular imaging platform—VasoVUE Research SystemTM—was designed to produce vessel-specific blood flow in the rat retina and cortex using laser speckle contrast imaging and high-speed photography. Image acquisition was synchronized with ECG, EEG, and BP recordings. An adult male Wistar rat (350g) was prepared by implanting EEG electrodes (right hemisphere) and exposing a thinned-skull cortical imaging window of 5mm diameter (left hemisphere). BP was measured by cannulating the left femoral artery. The rat was laid supine and the VasoVUE was oriented such that retinal and cortical vasculature was visualized clearly (Fig. 1). The rat was anesthetized with 2% isoflurane for 20 min. to establish baseline, after which a 5-min washout period (no isoflurane) was recorded. Asphyxia was induced by stopping mechanical ventilation for 6 min. Subsequently, cardiopulmonary resuscitation (CPR) was performed by ventilation, external chest compression, epinephrine and NaHCO3 until return of spontaneous circulation (ROSC, mean BP >50 mmHg). Recovery was monitored for 25 min.