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BACKGROUND: Following adult cardiac surgery, often difficult to detect fluctuations in regional cerebral perfusion can contribute to strokes. Optimal cerebral perfusion remains elusive and traditional monitoring strategies do not consistently identify acute changes. Non-invasive cerebral oximetry may detect perfusion variations. OBJECTIVE: To assess the feasibility of postoperative non-invasive cerebral oximetry monitoring. METHODS: Non-invasive cerebral oximetry was performed on adult aortic valve surgery patients in a cardiac surgical intensive care unit. Monitoring feasibility was assessed using an investigator-developed, data extraction tool. RESULTS: Non-invasive cerebral oximetry was completed in 94% of patients. Sixty percent had values that fell below pre-set ischemic threshold. Nurses reported monitoring was feasible, and they perceived identifying deleterious cerebral perfusion trends may improve patient care. CONCLUSIONS: Prevalence of low cerebral oximetry values underscores the importance of increasing sensitivity of monitoring tools. Further evaluation is required to assess this modality and the role of nurses in optimizing neurocognitive outcomes. Impact statement: Cerebral oximetry monitoring may help identify adult patients at risk of neurological complications after cardiac surgery, and as a consequence initiate definitive therapeutic strategies.

BACKGROUND: Following adult cardiac surgery, often difficult to detect fluctuations in regional cerebral perfusion can contribute to strokes. Optimal cerebral perfusion remains elusive and traditional monitoring strategies do not consistently identify acute changes. Non-invasive cerebral oximetry may detect perfusion variations. OBJECTIVE: To assess the feasibility of postoperative non-invasive cerebral oximetry monitoring. METHODS: Non-invasive cerebral oximetry was performed on adult aortic valve surgery patients in a cardiac surgical intensive care unit. Monitoring feasibility was assessed using an investigator-developed, data extraction tool. RESULTS: Non-invasive cerebral oximetry was completed in 94% of patients. Sixty percent had values that fell below pre-set ischemic threshold. Nurses reported monitoring was feasible, and they perceived identifying deleterious cerebral perfusion trends may improve patient care. CONCLUSIONS: Prevalence of low cerebral oximetry values underscores the importance of increasing sensitivity of monitoring tools. Further evaluation is required to assess this modality and the role of nurses in optimizing neurocognitive outcomes. Impact statement: Cerebral oximetry monitoring may help identify adult patients at risk of neurological complications after cardiac surgery, and as a consequence initiate definitive therapeutic strategies.

A study of the spray of a swirl coaxial gas-liquid injector operating at high-liquid momentum ratios is reported. Mixing and droplet size characteristics of the swirl injector are also compared to a shear coaxial injector, currently being used in the space shuttle main engine fuel preburner. The injectors were tested at elevated chamber pressures using water as a liquid oxygen stimulant and nitrogen and helium as gaseous hydrogen simulants. The elevated chamber pressure allowed for matching of several of the preburner injector conditions including gas/liquid momentum ratio, density ratio and Mach number. Diagnostic techniques used to characterize the spray included strobe backlight imaging, laser-sheet spray imaging, mechanical patternation, and phase Doppler interferometry. The results indicate that the radial spreading of the swirl coaxial spray is much less than was reported in previous studies of swirl injectors operating at atmospheric backpressure. The swirl coaxial spray did, however, exhibit a smaller overall droplet size., Pub. in Jnl. of Propulsion and Power, v17 n2 p402-410, March-April 2001.