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Abstract Background A pulse oximeter is one of the most important monitors to save patients undergoing anesthesia and monitored sedation. The authors report a case of orthopedic surgery, in which interference of pulse oximetry occurred when using a Stealth Station™ navigation system (Medtronic Sofamor Danek, Memphis, TN). Applying a black plastic shield (Masimo Ambient Shield: Masimo Corporation, Irvine, CA) completely eliminated the interference. Case presentation A 37-year-old male patient with a giant cell tumor of the left femur was scheduled to undergo curettage of the femur using an intraoperative CT three-dimensional imaging system (O-arm™) and Stealth Station™ navigation system. During the surgery, the SpO2 value, which was maintained between 97 and 99% until the time, disappeared suddenly with abnormal pulse wave. Because a distortion in the SpO2 value was reproduced by repeated movement of cameras on the head of the Stealth Station™ navigation system, we recognized that the interference signal was coming from the navigation system. To eliminate the infrared light, the pulse oximetry probe was covered with a black plastic shield and the interference was completely eliminated. Conclusions The Stealth Station™ navigation system was found to interfere with the SpO2 value, and a black plastic shield was useful for eliminating the interfering signal. Anesthesiologists should understand the risk of interference by the neuro-navigation system and know how to solve the problem.

The effect of the presence of a non-magnetic phase at multi-junctions of Nd2Fe14B grains on the demagnetization process of Nd-Fe-B magnets was investigated by micromagnetic simulations, while varying the size of the non-magnetic phase and the Nd2Fe14B grains. While the demagnetizing field created by the non-magnetic phase assisted the nucleation of a reverse domain, its effect was only significant when its size exceeded a critical value. This critical size effect can be explained by a change in the spatial distribution of the demagnetizing field. In addition, the calculations indicated that microstructural refinement would also increase the coercivity. This increase in coercivity could also be attributed to a change in the spatial distribution of the demagnetizing field due to the presence of a non-magnetic phase. Changes in the spatial distribution of the demagnetizing field due to such a non-magnetic phase could represent a mechanism by which microstructural refinement leads to increased coercivity. [ABSTRACT FROM AUTHOR]

A 3-year, retrospective, single-centre cohort study was conducted in a private infertility centre to determine cumulative live birth rates (LBR) per scheduled oocyte retrieval following minimal ovarian stimulation/natural-cycle IVF in unselected infertile patients. A total of 727 consecutive infertile patients were analysed who underwent 2876 (median 4) cycles with scheduled oocyte retrieval from November 2008 to December 2011. Natural-cycle IVF or clomiphene-based minimal ovarian stimulation was coupled with single-embryo transfer and increased use of delayed vitrified-warmed blastocyst transfer. Main outcome measures were crude and expected age-specific cumulative LBR per scheduled oocyte retrieval. Crude cumulative LBR were 65%, 60%, 39%, 15% and 5% in patients aged 26-34, 35-37, 38-40, 41-42 and 43-44 years, respectively. No live births occurred in patients aged >45 years. Dropout rates per cycle were 13-25%. Success rates gradually reached a plateau, with few additional live births after six cycles. Most of the expected success rate was reached within 6 months with almost maximal rates within 15 months of the first oocyte retrieval. Acceptable cumulative LBR are reached with an exclusive minimal ovarian stimulation/single-embryo transfer policy especially in patients aged <38 years but also in intermediate aged patients (38-40 years), [ABSTRACT FROM AUTHOR]