Repurposing CPAP machines as stripped-down ventilators.

The worldwide shortage of medical-grade ventilators is a well-known issue, that has become one of the central topics during the COVID-19 pandemic. Given that these machines are expensive and have long lead times, one approach is to vacate them for patients in critical conditions while patients with mild to moderate symptoms are treated with stripped-down ventilators. We propose a mass-producible solution that can create such ventilators with minimum effort. The central part is a module that can be attached to CPAP machines and repurpose them as low-pressure ventilators. Here, we describe the concept and first measurements which underline the potential of our solution. Our approach may serve as a starting point for open-access ventilator technologies.

Lunate biomechanics: application to Kienböck's disease and its treatment.

Kienböck's disease was initially considered as lunate osteomalacia due to lesions of its nutrient arteries during carpal ligament tears. It has also been suggested following primary fractures, or because of repeated microtrauma. It is only in the past 20 or 30 years that it has appeared as aseptic necrosis. Based on Hultén's hypothesis that a negative radioulnar index was the cause of Kienböck's disease, equalization osteotomies (shortening of the radius or lengthening of the ulna) were developed. The observation of Kienböck's disease in subjects with a positive index and the risk of ulnar abutment after osteotomy led to the introduction of new osteotomies to get around these difficulties, still in the hope of treating the cause of Kienböck's disease. While it has been confirmed that a negative radioulnar index promotes lunate fracture, it clearly does not induce the pathology in the form of necrosis. In this scenario, perilunar osteotomies produce durable decompression, limiting the risk of lunate fracture in case of necrosis by removing the compressive constraints. After comparing the different osteotomies used to treat Kienböck's disease, it seems that the Camembert osteotomy for radius shortening, combined with selective shortening of the ulnar head as described by Sennwald, decompresses the lunate maximally, and protects it long enough for potential natural revascularization to occur.

Ulna shortening osteotomy versus arthroscopic wafer procedure in the treatment of ulnocarpal impingement syndrome.

Post-traumatic or constitutional ulnar impaction syndrome can be treated by shortening the ulna. This can be achieved by diaphyseal or metaphyseal osteotomy, or by arthroscopic epiphyseal resection. The objective of this study was to compare the results of the diaphyseal shortening osteotomy (USO) and arthroscopic wafer procedure (AWP) of the ulna in this indication. This was a retrospective case series of 33 patients operated for ulnar impaction syndrome by the same surgeon between 1997 and 2017. The diagnosis was made based on pain on the ulnar edge of the wrist with positive provocative tests. Radiographs were made and CT arthrography or MRI were used to confirm the diagnosis. Per-and post-operative assessments were functional (DASH and PRWE scores), clinical (pain, range of motion and grip strength) and radiographic. Diaphyseal ulnar shortening osteotomy (USO) was performed in 9 patients using a volar plate and a cutting guide. Twenty-four patients underwent an arthroscopic wafer procedure. Mean follow-up was 103 ± 8 months in the USO group versus 55 ± 4 months in the AWP group. There was no significant difference between groups in pain levels (1.2/10 in the USO group versus 0.9/10 in the AWP group, p = 0.88), grip strength (39 Kg in the USO group versus 34 Kg in the AWP group, p = 0.27) and PRWE score (5,8/100 in the USO group versus 11,2 in the AWP group, p = 0.34), and DASH score (25/100 in the USO group versus 28 in the AWP group, p = 0.63). The time away from work was long in the USO group than in the AWP group (7.86 months versus 3.75 months) (p = 0.002). Seven patients were reoperated in the USO group (5 plate removal, 1 nonunion and 1 delayed union) versus 3 in the AWP group (1 ECU stabilization, 1 ablation for painful ulnar styloid due to nonunion and 1 wrist denervation) (p = 0.0004). The study found no clinical differences between these two techniques except the return to work time. In our series, diaphyseal USO was associated with a greater number of reoperations than the AWP.

Arthroscopic-assisted 6U approach for foveal reattachment of triangular fibrocartilage complex with an anchor: Clinical and radiographic outcomes at 4 years' mean follow-up.

The main objective of this study was to evaluate the long-term clinical and radiological outcomes of arthroscopic-assisted foveal repair of proximal triangular fibrocartilage complex (TFCC) tears with an anchor. The secondary objective was to look for ligament damage associated with TFCC tears. Twenty-four patients who underwent foveal repair of the TFCC were evaluated retrospectively: 16 stage 2 and 8 stage 3 in the Atzei-EWAS classification. The TFCC was repaired with an anchor using an expanded 6U approach. Systematic testing of intrinsic and extrinsic ligaments was performed. The assessment criteria were pain on a visual analog scale (VAS), wrist joint range of motion, grip strength and pronation-supination strength, and the QuickDASH and PRWE outcome scores. X-rays were also taken to assess anchor position and to look for distal radioulnar (DRU) joint damage. The average follow-up was 44 months. After the surgical repair, pain was reduced (7.36±1.3 preoperatively vs. 0.69±1.3 postoperatively; P<0.001), the QuickDASH score improved (52.1±16 vs. 21.7±7; P<0.001), the PRWE score improved (83.7±35 vs. 9.3±12; P<0.001) as did strength (35 vs. 43kg; P<0.001). The DRU joint stability was also significantly improved. The time away from work was 2.6 months. During the arthroscopy exploration, 25% of patients had an ulnotriquetral ligament lesion and 8% had an ulnolunar ligament lesion in combination with their TFCC tear. Fifteen anchors were positioned in the anatomical fovea (62%). No DRU joint damage was noted. Six patients had neurapraxia of the dorsal branch of the ulnar nerve, although it recovered spontaneously. One patient still had hypoesthesia of the ulnar side of the fifth finger at 48 months. Arthroscopic-assisted foveal repair of the TFCC yields good results in terms of pain, strength and DRU joint stability. In one-quarter of cases, TFCC foveal tears are associated with lesions of the ulnotriquetral ligament. There is no long-term degeneration of the DRU joint.

Artificial dielectric stepped-refractive-index lens for the terahertz region.

In this paper we theoretically and experimentally demonstrate a stepped-refractive-index convergent lens made of a parallel stack of metallic plates for terahertz frequencies based on artificial dielectrics. The lens consist of a non-uniformly spaced stack of metallic plates, forming a mirror-symmetric array of parallel-plate waveguides (PPWGs). The operation of the device is based on the TE1 mode of the PPWG. The effective refractive index of the TE1 mode is a function of the frequency of operation and the spacing between the plates of the PPWG. By varying the spacing between the plates, we can modify the local refractive index of the structure in every individual PPWG that constitutes the lens producing a stepped refractive index profile across the multi stack structure. The theoretical and experimental results show that this structure is capable of focusing a 1 cm diameter beam to a line focus of less than 4 mm for the design frequency of 0.18 THz. This structure shows that this artificial-dielectric concept is an important technology for the fabrication of next generation terahertz devices.

Terahertz imaging for early screening of diabetic foot syndrome: A proof of concept.

Most people with diabetes suffer some deterioration of the feet. Diabetic foot syndrome causes ulceration in about 15% of cases and such deterioration leads to amputation in about 2.5% of diabetic patients, diminishing their quality of life and generating extraordinary costs for patients and public health systems. Currently, there is no objective method for the detection of diabetic foot syndrome in its early stages. We propose terahertz imaging as a method for the evaluation of such deterioration. This screening method could aid the prevention and medical treatment of this condition in the future.

Terahertz meets sculptural and architectural art: Evaluation and conservation of stone objects with T-ray technology.

Conservation of cultural heritage is an area where novel scientific techniques are having enormous impact. Given the value and uniqueness of art pieces, non-invasive diagnostic methods are highly appreciated by conservators. Terahertz radiation has shown enormous potential as non-contact probe that can be used for the three-dimensional reconstruction of internal structure of stone-made objects. In this article we report the evaluation of the internal damage state of two art pieces, a medallion from the Castle of Celle and a window sill from the St. Peter of Trier Cathedral. We also used terahertz radiation to follow and assess the restoration process of the window sill. We found that terahertz spectroscopy is an excellent non-destructive evaluation method for stone artwork that shows enormous potential as a tool for conservation.

Modifying the polarization state of terahertz radiation using anisotropic twin-domains in LaAlO3.

Polarization-resolved terahertz (THz) time-domain spectroscopy was utilized to examine the complex refractive index of lanthanum aluminate (LaAlO3), a rhombohedrally distorted perovskite that exhibits crystallographic twin domains. The uniaxial anisotropy of the refractive index was quantified. The ellipticity of THz radiation pulses after transmission through single domains indicated that LaAlO3 can be used as a quarter- or half-wave plate. The effective anisotropy of [001]-oriented LaAlO3 was found to be reduced when the material exhibited multiple, narrow twin domains.

Quality control of leather by terahertz time-domain spectroscopy.

We use terahertz time-domain spectroscopy, combined with effective-medium theory, to measure the moisture content and thickness of leather simultaneously. These results demonstrate that this method could become a standard quality control test for the industrial tanning process.

Dorsal scapholunate stabilization using Viegas' capsulodesis: 25 cases with 26 months-follow-up.

Intercarpal instability is often secondary to a scapholunate interosseous (SLIO) ligament lesion. Its reconstruction is thus essential. Classical capsulodesis techniques fix the scaphoid in extension and do not reproduce the physiologic ligamentous isometry of the wrist. The authors use the technique of Viegas, which seems to respect this isometry: the dorsal intercarpal ligament is re-inserted dorsally to reattach the capsule on the dorsal SLIO and to reinforce it. Between 2006 and 2010, 25 wrists were operated on in 12 men and 12 women of mean age 38 years. All patients presented with pain often associated with loss of power, decreased mobility or a debilitating click. The mean follow-up was 26 months. Postoperative and preoperative data were compared. Flexion/extension range increased by 2.6°, radioulnar deviation increased by 21.1°. Grip strength increased by 8.7 kgf. Pain decreased by 3 points on the VAS and the PRWE improved by 59 points. We observed four CRPS, one EPL lesion and one case of superficial track pin infection. We got eleven excellent results, nine good, two moderate and three bad, two of which were re-operated. Viegas' capsulodesis does not present major technical difficulty. The results show no stiffness in flexion/extension. There was evident improvement in radioulnar deviation, grip strength, pain and PRWE scores. This technique provides effective treatment for a difficult or irreparable lesion of the SLIO ligament, without fixed carpal instability corresponding to Geissler arthroscopic stages 2 to 4 and Garcia-Elias stages 3 and 4. The capsulodesis produces an effective stabilization without stiffness. Precautions should be undertaken to avoid CRPS and pin complications.

Leaf water dynamics of Arabidopsis thaliana monitored in-vivo using terahertz time-domain spectroscopy.

The declining water availability for agriculture is becoming problematic for many countries. Therefore the study of plants under water restriction is acquiring extraordinary importance. Botanists currently follow the dehydration of plants comparing the fresh and dry weight of excised organs, or measuring their osmotic or water potentials; these are destructive methods inappropriate for in-vivo determination of plants' hydration dynamics. Water is opaque in the terahertz band, while dehydrated biological tissues are partially transparent. We used terahertz spectroscopy to study the water dynamics of Arabidopsis thaliana by comparing the dehydration kinetics of leaves from plants under well-irrigated and water deficit conditions. We also present measurements of the effect of dark-light cycles and abscisic acid on its water dynamics. The measurements we present provide a new perspective on the water dynamics of plants under different external stimuli and confirm that terahertz can be an excellent non-contact probe of in-vivo tissue hydration.

Beating the wavelength limit: three-dimensional imaging of buried subwavelength fractures in sculpture and construction materials by terahertz time-domain reflection spectroscopy.

We use reflection terahertz spectroscopy to locate and produce three-dimensional images of air gaps between stones that resemble fractures, even of subwavelength thicknesses. This technique is found to be promising tool for sculpture and building damage evaluation as well as structural quality control in other dielectric materials.

Arthroscopic criteria for dating wrist sprains.

OBJECTIVES: Dating wrist sprains has therapeutic and medicolegal importance. The authors propose a study validating three arthroscopic criteria to date the trauma. METHODS: The authors analyzed statistically one hundred arthroscopies performed between 1999 and 2008 after wrist sprains. They suggest three criteria to date the injury. They are: turbidity of synovial fluid (assessed T0 to T4), hemorrhagic infiltration of the synovium (evaluated S0 to S2), and the aspect of the articular cartilage (assessed C0 to C4). RESULTS: The importance of turbidity is significant with P<0.001. The importance of synovitis is significant with P<0.001. The extent of cartilage degradation is significant with P<0.01. These three criteria have also a very significant predictability. The authors distinguish four posttraumatic periods: the immediate period, less than 2 weeks, corresponding to T3/T4, S2, C0; the acute period from 2 to 6 weeks, corresponding to T1/T2, S1, C1/C2; the subacute period from 6 weeks to 6 months, corresponding to T0, S1, C3; the chronic period beyond 6 months, corresponding to T0, S0, C4. The association T2/T4, S2, C4 is clearly an acute injury with a previous pathologic situation. CONCLUSIONS: The arthroscopic criteria for dating a wrist sprain are simple to estimate. They are used to define the immediate, acute, subacute or chronic posttraumatic periods, and a previous pathologic situation. The choice of surgical indication is facilitated and an objective estimation of the length of lesion is useful in the forensic setting.

An ion-implanted InP receiver for polarization resolved terahertz spectroscopy.

We report on the construction, optical alignment and performance of a receiver which is capable of recording the full polarization state of coherent terahertz radiation. The photoconductive detector was fabricated on InP which had been implanted with Fe(+) ions. The device operated successfully when it was gated with near infrared femtosecond pulses from either a Ti:sapphire laser oscillator or a 1 kHz regenerative laser amplifier. When illuminated with terahertz radiation from a typical photoconductive source, the optimized device had a signal to noise figure of 100:1 with a usable spectral bandwidth of up to 4 THz. The device was shown to be very sensitive to terahertz polarization, being able to resolve changes in polarization of 0.34 degrees. Additionally, we have demonstrated the usefulness of this device for (i) polarization sensitive terahertz spectroscopy, by measuring the birefringence of quartz and (ii) terahertz emission experiments, by measuring the polarization dependence of radiation generated by optical rectification in (110)-ZnTe.

[Medical treatment of ectopic pregnancy: a randomized clinical trial comparing metotrexate-mifepristone and methotrexate-placebo]. / Traitement médical des grossesses extra-utérines: un essai clinique randomisé comparant méthotrexate-mifépristone et placebo-méthotrexate.

BACKGROUND: Medical treatment of ectopic pregnancy is widespread. To increase the efficacy of methotrexate, combination with mifepristone has been proposed. METHODS: We performed a large prospective multicentre double-blind sequential randomized trial in order to compare the efficacy of methotrexate and mifepristone (600 mg given orally) versus methotrexate and placebo. RESULTS: Two hundred twelve ectopic pregnancies were randomized. There was no significant difference in the initial characteristics between the 2 groups. There was no significant difference in the success rate of medical treatment between the methotrexate-mifepristone (n=113) and the methotrexate-placebo group (n=99): 79.6% (90/113) vs 74.2% (72/97) respectively, RR [95% CI]: 1.07 [0.92-1.25], p=0.41. However, there was a quantitative interaction between progesterone level and effect of treatment: when progesterone level was 10 ng/l, the efficacy of the combination of mifepristone and methotrexate was significantly higher than the combination of methotrexate and placebo, with a 83.3% success rate (15/18) vs 38.5% (5/13) respectively. CONCLUSION: Our study failed to demonstrate any benefit of the addition of mifepristone to methotrexate. By contrast, the quantitative interaction between treatment effect and base line serum progesterone suggested that this combination could be reserved to ectopic pregnancies associated with high serum progesterone concentrations.

Kinematics of the wrist using 2D and 3D analysis: biomechanical and clinical deductions.

Surgery of the wrist relies on the known notions of biomechanics of the wrist. But these notions are incomplete. For a better understanding of the movements of the wrist, we studied five wrists of healthy volunteers with CT scanning. Each wrist was studied in neutral position, and in the four extreme positions: flexion, extension, radial and ulnar deviations. Using oblique reformatted CT sections, we measured the angular displacements in frontal and sagittal views of every carpal bone in the different positions of the wrist. This allowed us to construct a table of intracarpal mobility. By comparing the angle values and the three-dimensional pictures of these wrists, we illustrate some fundamental points regarding intracarpal movement. The dynamics of the wrist are like those of two super-imposed mobile cups with different movements. The proximal row is malleable with flattening and torsion according to the transverse axis and its behavior is like that of an articular meniscus. The distal row, more rigid but deformable, behaves like a T-handle giving attachment to the hand and articulating under the proximal row around the head of the capitate and the proximal pole of the hamate. During radial and ulnar deviations of the wrist, the movement between the two rows is like an inverse pronation-supination shearing. During flexion-extension, the distortion of the two rows allows maximal congruence to be maintained between the different carpal bones.

[Expectative management: a valid option for ectopic pregnancy]. / Place réelle de l'abstention dans le traitement de la grossesse extra-utérine.

Advances in laboratory tests and transvaginal ultrasound have enabled very early diagnosis of ectopic pregnancy. Expectative management has progressively become a real medical option for ectopic pregnancies as an alternative to surgery or medical treatment. The decision to abstain from treatment must be based on very strict criteria: patients with no symptoms, hematosalpinx<3 cm, no hemoperitoneum, hCG level<1000 mUI/ml and decreasing 48 hours later, a progesterone level<10 ng/ml. Regular surveillance until normalization of clinical, ultrasound and biological results is essential. The rate of success, which reaches 90%, clearly justifies this medical option.

Abdominal wall metastasis of a cervical adenocarcinoma at the laparoscopic trocar insertion site after ovarian transposition: case report and review of the literature.

BACKGROUND: Laparoscopic ovarian transposition is currently used in the preirradiation management of cervical cancer in young women. This surgical technique helps avoid the short- and long-term complications of early menopause. Because there remains a risk of metastasis at the site where the laparoscopic trocar is inserted, more precise indications for this surgery are required. CASE: We report the case of a patient with an abdominal wall metastasis that followed laparoscopic ovarian transposition performed before radiation therapy and surgical treatment for a stage IIb cervical adenocarcinoma. Observations during the laparotomy nonetheless led us to resect the transposed ovary during the laparotomy. The pathology examination of the ovary found a microscopic metastasis. Several months later, a left abdominal parietal nodule, corresponding to a metastasis of the adenocarcinoma, was found on the site through which the trocar had been inserted during the laparoscopy and was probably associated with the ovarian transposition. CONCLUSION: This is the only published case to describe an abdominal wall metastasis due to laparoscopic trocar insertion during ovarian transposition. The decision to perform a laparoscopic ovarian transposition in cervical cancer must take into account the frequency of trocar site metastases, which seems to be higher with advanced-stage cervical cancers, in cases of lymph node involvement and especially in adenocarcinomas.

Prediction of the physical response for the two-photon photorefractive effect.

We present a new model for the two-photon photorefractive recording process. We solved the resulting set of nonlinear coupled partial differential equations of the model within a linear approximation of the steady state. We found very good agreement with experimental results.