OBJECTIVE: This study aimed to develop and validate a prediction model for premature circuit clotting of continuous renal replacement therapy (CRRT) in critically ill patients. DESIGN: A retrospective cohort study was conducted on ICU patients undergoing CRRT. The Medical Information Mart for Intensive Care-III Clinical Database CareVue subset and Medical Information Mart for Intensive Care-IV were utilized for model development, while the eICU Collaborative Research Database was employed for external validation. Predictive factors were selected through Least Absolute Shrinkage and Selection Operator Regression and univariate logistic regression. A prediction model was then developed using binary logistic regression. Internal and external validations assessed the model's discrimination, calibration, and clinical net benefit. RESULTS: This study encompassed 2531 patients overall, with a premature circuit clotting rate of 31.88 %. The prediction model comprises five variables: body temperature, anticoagulation, mean arterial pressure, maximum transmembrane pressure change within two hours, and vasopressor. The model demonstrated robust predictive performance, achieving an area under the receiver operating characteristic curve of 0.897 (95 % CI: 0.879-0.915) in the training set and 0.877 (95 % CI: 0.852-0.902) in the external validation set. Internal validation yielded a Brier score of 0.087, while external validation showed a Brier score of 0.120. Calibration curves indicated good model calibration for both validations. The decision curve analysis indicates that the model yields a clinical net benefit across a wide range of decision thresholds. CONCLUSION: The model demonstrates robust discrimination, calibration, and clinical net benefit, with readily available variables indicating substantial potential for valuable clinical applications. IMPLICATIONS FOR CLINICAL PRACTICE: Healthcare providers in the ICU can leverage the model to evaluate the risk of premature circuit clotting in critically ill patients undergoing continuous renal replacement therapy, facilitating timely intervention to mitigate its incidence.
The aim of the present study was to explore the association between anemia and the risks and outcomes of diabetic foot (DF) in patients with type 2 diabetes mellitus (T2DM). A total of 145 patients with T2DM were recruited between January and December 2021 and divided into the DF and non-DF groups according to whether they were diagnosed with DF. Individual patient data were extracted and blood samples were evaluated in a biochemical center for routine biochemical and blood-related indicators. The patients' survival rates were followed up until December 2022. An independent-samples t-test and χ2 test were used to compare the differences between the two groups. The association between the various clinical indicators for the DF and non-DF groups was evaluated using single-factor binary logistic regression analysis. Multi-factor binary logistic regression analysis was used to analyze the association between hemoglobin (Hb) and the risk for DF. A Kaplan-Meier survival curve was used to analyze the impact of anemia and DF on the 1-year survival rate. The diabetes duration, number of patients who smoked and consumed alcohol, and serum creatinine and C-reactive protein levels in the DF group were significantly higher than those in the non-DF group (P<0.05). By contrast, the estimated glomerular filtration rate (eGFR) and Hb, albumin (Alb) and total cholesterol levels, were lower in the DF group when compared with those in the non-DF group (P<0.05). All of the study participants were divided into two groups, according to their baseline eGFR [eGFR ≥90 or <90 ml/(min x 1.73 m²)]. It was found that, independently of renal function, lower Hb and Alb levels were associated with a higher incidence of DF. The 1-year survival rate for DF with anemia was significantly lower when compared with that in patients with DF without anemia (P<0.05). In conclusion, the Hb level in patients with T2DM is a protective factor against DF and anemia is an independent risk factor for DF. The present study suggested that anemia is associated with a decrease in the survival rate of patients with DF. This finding provided a theoretical basis for the clinical correction of anemia and improvement of DF prognosis (clinical trial no. 20220003).
A laser-based spectrometer with a physical size of 60× 30 ×25â¯cm3 has been developed to continuously monitor CO and CH4 in atmosphere based on tunable diode laser absorption spectroscopy (TDLAS). Two neighboring lines of CO and CH4 around 2.3 µm were selected as candidates for simultaneous measurement by a single diode distributed feedback (DFB) laser. A special Herriott-type multipass absorption cell, with a 72â¯m optical path length, was designed and used to enhance the absorption signals of sample gases. Normalized wavelength modulation spectroscopy was applied to improve the sensitivity and robustness of the spectrometer and it was implemented on a home-made electronic system based on field programmable gate array (FPGA). Meanwhile, the electronic system controlled the temperature and current of DFB laser with the precision of 0.01⯰C and 40â¯ppm. The 2nd-harmonic signals normalized by the corresponding 1st-harmonic signals for both CO and CH4 are of high linear response to their concentrations in the range of 0.046-4.6â¯ppm and 0.487-48.7â¯ppm, respectively. According to the Allan variance, respective minimum detection limits for CO and CH4 are 0.73â¯ppb and 36â¯ppb at 122â¯s and 137â¯s. As an application example, the spectrometer has been validated through real-time and in-situ measurement of atmospheric CO and CH4 for 48â¯h.
Quantum time-dependent wave-packet calculations have been carried out to explore the state-to-state dynamics of the ion-molecule (H-(D-),HD) collisions on two accurate ab initio potential energy surfaces in the collision energy range 0.2-1.2 eV. Total and final state-resolved integral and differential cross sections are elaborated in detail. The differential cross sections vary substantially with the collision energy, turning from predominantly backward-scattering at low collision energies to forward and sideways scattering bias at relatively high collision energies. The rebound, stripping and time-delayed mechanisms are found to be possible in (H-(D-),HD) collisions. A set of quasi-classical trajectory calculations were performed, and the results indicate that the backward-scattering peak is caused by the low impact parameter trajectories, while the trajectories of high impact parameter are responsible for the forward scattering. A set of representative state-to-state differential cross sections at collision energies 0.6 and 1.2 eV are also presented. Different reaction mechanisms are dominant in (H-(D-),HD) collisions at different collision energies, resulting in different product rovibrational state distributions. The differences between the dynamics results based on the two potential energy surfaces are also discussed.
A low-noise, low power, high modulation-bandwidth design integrated laser current and temperature driver with excellent long-term stability is described. The current driver circuit is based on the Hall-Libbrecht design. A high sensitivity and a stable driver current were obtained using a differential amplifier and an integral amplifier. The set-point voltage for the current driver came from an ultra-compact, ultra-low temperature coefficient voltage reference chip or the digital to analog convertor output of a microcontroller or a modulation signal. An integral temperature chip, referred to as ADN8834, was used to drive the thermoelectric cooler controller of the distributed feedback (DFB) laser. The internal amplifier acquired the feedback current of the temperature sensor. The proportional-integral-derivative parameters such as proportion, integration, and derivative were set by external resistors. The short- and long-term stability and linearity of the developed laser driver were tested using a DFB laser with a central wavelength of 6991 cm-1. The laser driver was validated for high-sensitivity gas sensing of CO2 and C2H2 via a laser absorption spectroscopy experiment. The limits of detection were less than 11.5 ppm and 0.124 ppm for CO2 and C2H2, respectively. Direct absorption measurements and the 1-f and 2-f demodulation signals confirmed the capabilities of the proposed laser driver system in high-sensitivity gas sensing applications. The driver unit can readily be accommodated into many portable laser sensing devices for industrial applications.
We report a multi-pass tunable diode laser absorption spectrometer based on the frequency-modulation spectroscopy (FMS) technique. It has the advantage of high scan speed and is immune to the etalon effect. A multi-pass Herriott-type cell was used in the spectrometer to increase the effective optical length to 17.5 m and compact the physical dimensions of the spectrometer to 60×30×30 cm3. Noise due to low-frequency fluctuation of the laser power and the 1/f noise in the rapid detection are sufficiently reduced by FMS. Interference fringes are effectively suppressed when the modulation frequency equals to integer or half-integer times of their free spectral range (FSR). An absorption line of C2H2 around 1.51 µm was recorded with the spectrometer to demonstrate its capabilities. The response frequency of the spectrometer is up to 100 kHz (10 µs) thanks to the high modulation frequency of FMS. The detection sensitivity of the spectrometer is about 240 ppb (3σ) at 100 kHz measurement repetition rate. The amplitude of the absorption signal is highly linear to the C2H2 concentration in the range of 300 ppb -100 ppm. Based on the Allan variation, the detection limit was determined to be 18 ppb with a detection time of 166 s.
A resolved line pair was selected for simultaneous measurement of carbon monoxide (CO) and carbon dioxide (CO2) in the near-infrared (NIR) region. The spectral lines of CO and CO2 at 1.578 µm were measured by wavelength modulation spectroscopy (WMS)-2 f and the absorption was enhanced with a multipass absorption cell. The white noise was further reduced by averaging technology. The detection sensitivity (1σ) for the system is estimated at 2.63 × 10-7 cm-1 for direct absorption spectroscopy. The ultimate detection limits of CO2 and CO mixed with pure N2 at 75 Torr are 29 parts per million (ppm) and 47 ppm, respectively. It is demonstrated that the signal is highly linear with the concentration in the range of 100-800 ppm. Based on an Allan variation analysis, the minimum detectable limit of CO2 and CO is 7.5 and 14 ppm, respectively. The response time of the system is about 30 s and a relationship of temperature dependence was obtained. As an example, an in situ measurement of exhaust of alkane combustion emission is presented.
Wavelength modulation spectroscopy (WMS) combined with a multipass absorption cell has been used to measure a weak absorption line of carbon monoxide (CO) at 1.578 µm. A 0.95m Herriott-type cell provides an effective absorption path length of 55.1 m. The WMS signals from the first and second harmonic output of a lock-in amplifier (WMS-1 f and 2 f, respectively) agree with the Beer-Lambert law, especially at low concentrations. After boxcar averaging, the minimum detection limit achieved is 4.3 ppm for a measurement time of 0.125 s. The corresponding normalized detection limit is 84 ppm m Hz-1/2. If the integrated time is increased to 88 s, the minimum detectable limit of CO can reach to 0.29 ppm based on an Allan variation analysis. The pressure-dependent relationship is validated after accounting for the pressure factor in data processing. Finally, a linear correlation between the WMS-2 f amplitudes and gas concentrations is obtained at concentration ratios less than 15.5%, and the accuracy is better than 92% at total pressure less than 62.7 Torr.
Air Pollutants/analysis , Carbon Monoxide/analysis , Spectroscopy, Near-Infrared/methods , Equipment Design , Limit of Detection , Linear Models , Pressure , Reproducibility of Results
With the rapid development of social economy, the environmental pollution and the ecological destruction are continuously deteriorating while sudden environmental pollution incidents occur frequently. Real-time monitoring harmful gases of the air take advantages of spectroscopic techniques for concentration measurement. Multipass optical cells are -widely used in absorption spectrometry technique to improve gas detection sensitivity under the condition of weak absorption. This paper proposes a spiral-torus type multipass optical device base on the structure of Herriott type cell. The optical device consists of multiple torus concave mirrors in a spiral way. Incident light propagates along with radical and axial direction in winding staircase pattern. The faculae on the inner wall present a spiral-type. The entrance and exit apertures are separated due to the spiral trace of optical rays, which increases the accessible adjustment of the apparatus. The effective optical length can be adjusted based on the proportional relationship to the reflective times. This device is characterized with easy adjustment and excellent mechanical performance due to its cylindrical structure. Based on ABCD matrix, the stability of the system was analyzed and the relationship between the number of reflections and the incident angle were discussed. With optical simulation software, we designed a device for separating polarized light, and the characteristics of its rotation was studied.
The concentration of inhalable particle is an important indicator in atmospheric environment monitor. Based on Mie scattering extinction, a precise testing instrument which can measure the concentration of inhalable particles at the atmospheric was designed by three-wavelength method in combination with the algorithm of distributed function. The dependence of extinction index on the spectrum was calculated based on Mie scattering theory in this article. Furthermore, the signal of time domain is integrated in the data processing to reduce the effect of error caused by multi-peak of spectra. The PM2.5 and PM10 were collected simultaneously in particle selection. Three different wave-lengths of lasers were coupled into an optical fiber by coupler (3 in 1) and passed through the sample cell. The attenuated light was detected by a PIN. Output of the detector was converted, amplified, displayed and stored by electronic system. Finally, the data were transmitted and shared in network through the 3G wireless module. The average particle size and concentration of inhalable particles were measured by this device at the same time. The technical specifications of the detector were verified by experiment, the experimental results indicate that the detection sensitivity of the system is 0.01 microg m(-3), the responsive time of system is approximately 90 s and it is suitable for measuring particulate matter concentrations of atmosphere.
