The design and evaluation of a novel low-cost portable ventilator.

Modern mechanical ventilator technologies broadly consist of digitally-controlled electronic devices and analogue systems driven by compressed gas sources. Drawbacks such as high cost, complex maintenance and the need for cumbersome sources of compressed driving gas hinder adoption in pre-hospital and low-resource environments. We describe the evaluation and testing of a simple, low-cost alternative ventilator that uses a novel pressure-sensing approach and control algorithm. This is designed to provide portable positive-pressure mechanical ventilation at a reduced cost, while autonomously monitoring patient condition and important safety parameters. A prototype ventilator was constructed and evaluated using an anaesthetic test-lung as a patient surrogate. Using a modifiable test-lung and digital pressure sensor, we investigated ventilation pressure waveform circuit leak detection, and compliance and resistance change detection. During intermittent positive-pressure ventilation to the test-lung, the prototype system showed acceptable pressure waveform parameters: all simulated circuit leaks ≥ 6 mm2 in size were detected; compliance changes were detected between 10 ml.cmH2 O-1 , 20 ml.cmH2 O-1 and 50 ml.cmH2 O-1 ; and resistance changes were detected across the available simulated range. These results show this prototype technology has the potential to provide safe emergency ventilation without the use of any complex digital sensors or software while its construction and design enables significant reductions in cost and complexity. The study suggests further work is now justified in progressing the technology to clinical trials.

3D printing in dentistry.

3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

A novel alignment device for cone beam computed tomography: principle and application.

OBJECTIVES: the aim of this investigation was to optimize the positioning and size of the scanned field of view (FOV) in cone beam CT (CBCT) scanners using a practical external alignment device fitted in the patient's mouth in order to train radiographers and reduce radiation dose to the patient. This is particularly challenging when using small FOVs to cover small volumes of interest. METHODS: test objects were positioned and scanned using the aligner to show that the design and geometry were correct and help the radiographer to superimpose the scanner and the volume of interest axis of rotation. An in vivo study was then undertaken comparing the accuracy of patient positioning when using the aligner, instead of scouts, to position the patient for small FOV (cylinders of 4-8 cm height and 4-8 cm diameter) dental scans. The scanners used were the Accuitomo F170 CBCT scanner (Morita, Kyoto, Japan) and the iCAT Next Gen CBCT scanner (Imaging Sciences, Hatfield, PA). RESULTS: there was no significant difference in positioning the patient when using the aligner compared with the scout images. CONCLUSIONS: it is possible to rely on the aligner for patient positioning for a small volume scan and therefore spare the radiation dose associated with scout imaging.