A Low-Resource Oxygen Blender Prototype for Use in Modified Bubble CPAP Circuits: Results from Design Feasibility Workshops.

Bubble CPAP is used in low-resource settings to support children with pneumonia. Low-cost modifications of bubble CPAP using 100% oxygen introduces the risk of hyperoxia. Our team developed a low-cost, readily constructible oxygen blender to lower the oxygen concentration. The next step in development was to test its construction among new users and ascertain three outcomes: construction time, outflow oxygen concentration, and an assessment of the user experience. Workshops were conducted in two countries. Instructions were delivered using a live demonstration, a video, and written instructions in the respective native language. Twelve volunteers participated. Average construction times were 24 minutes for the first attempt and 15 minutes for the second. The oxygen concentrations were 53-63% and 41-51% for the 5 and 10 mm entrainment ports, respectively. This novel, low-cost oxygen blender for bubble CPAP can be constructed among new users with reliable performance across devices.

Comparison of a new intramedullary scaffold to volar plating for treatment of distal radius fractures.

OBJECTIVES: To compare the biomechanical properties of a new nitinol intramedullary (IM) scaffold implant with those of volar plates for the treatment of dorsally comminuted extra-articular distal radius fractures using an established model. METHODS: A dorsal wedge osteotomy was performed on a bone model to simulate a dorsally comminuted extra-articular distal radius fracture. This model was used to compare stiffness of 3 different distal radius fixation devices--an IM scaffold implant, a commercially available titanium volar locking plate, and a stainless steel non-locking T-plate. Six constructs were tested per group. Tolerance for physiological loading was assessed by applying 10,000 cycles of axial loading up to 100 N applied at 2 Hz. Axial and eccentric load stiffness were assessed before cyclic loading and axial stiffness again after cyclic loading. Groups were compared using analysis of variance. RESULTS: Initial axial stiffness (in Newton per millimeter) was significantly (P = 0.011) different only between the volar locking plate (427 ± 43) and non-locking T-plate (235 ± 69). After cyclic loading, axial stiffness was not significantly different between the volar locking plate (392 ± 67) and IM scaffold implant (405 ± 108), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (187 ± 53). Eccentric loading stiffness was not significantly different between the IM scaffold implant (67 ± 140) and volar locking plate (63 ± 5), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (25 ± 4). CONCLUSIONS: Stiffness of the IM scaffold implant and volar locking plate fracture model constructs was equivalent. Biomechanical testing suggests that this novel IM scaffold provides sufficient stability for clinical use, and further testing is warranted.