Prone Dispatch-Directed CPR in Out-of-Hospital Cardiac Arrest: Two Successful Cases.

Historically, dispatch-directed cardiopulmonary resuscitation (CPR) protocols only allow chest compression instructions to be delivered for patients able to be placed in the traditional supine position. For patients who are unable to be positioned supine, the telecommunicator and caller have no option except to continue attempts to position supine, which may result in delayed or no chest compressions being delivered prior to emergency medical services arrival. Any delay or lack of bystander chest compressions may result in worsening clinical outcomes of out-of-hospital cardiac arrest (OHCA) victims. We present the first two cases, to the best of our knowledge, of successfully delivered, bystander-administered, prone CPR instructions by a trained telecommunicator for two OHCA victims unable to be positioned supine.

Dynamic closed-loop system for focus tracking using a spatial light modulator and a deformable membrane mirror.

A dynamic closed-loop method for focus tracking using a spatial light modulator and a deformable membrane mirror within a confocal microscope is described. We report that it is possible to track defocus over a distance of up to 80 microm with an RMS precision of 57 nm. For demonstration purposes we concentrate on defocus, although in principle the method applies to any wavefront shape or aberration that can be successfully reproduced by the deformable membrane mirror and spatial light modulator, for example, spherical aberration.

Exploration of the optimisation algorithms used in the implementation of adaptive optics in confocal and multiphoton microscopy.

We report on the introduction of active optical elements into confocal and multiphoton microscopes in order to reduce the sample-induced aberration. Using a flexible membrane mirror as the active element, the beam entering the rear of the microscope objective is altered to produce the smallest point spread function once it is brought to a focus inside the sample. The conventional approach to adaptive optics, commonly used in astronomy, is to utilise a wavefront sensor to determine the required mirror shape. We have developed a technique that uses optimisation algorithms to improve the returned signal without the use of a wavefront sensor. We have investigated a number of possible optimisation methods, covering hill climbing, genetic algorithms, and more random search methods. The system has demonstrated a significant enhancement in the axial resolution of a confocal microscope when imaging at depth within a sample. We discuss the trade-offs of the various approaches adopted, comparing speed with resolution enhancement.

General purpose control system for scanning laser ophthalmoscopes.

A flexible control system for scanning laser ophthalmoscopes is described that is quick and simple to configure, easily modified or adapted, and containing many useful features. The system facilitates adjustment of several parameters to account for changes to the scan position, ambient light and temperature, including both optical and electronic components, which is otherwise difficult and time-consuming to perform. The system is portable and uses custom-designed printed circuit boards. All system parameters, such as focus, scan rate,scan depth and stereo control can be digitally controlled from a computer via a single serial port. Custom software allows changes to any system parameters by simply sending the required control data to the rack. The circuit boards in the system are multilayer,incorporating good ground-plane techniques to minimize noise, programmable logic and semicustom logic for low cost and compact size, and microcontrollers with embedded firm ware for flexible operation. Retinal images demonstrate that the system performs well.