Design of liquid level detection circuit based on sampling probe structure capacitance.

Liquid level detection system is an essential core functional component of automatic clinical medical testing instrument. The conventional liquid level detection method has low detection accuracy and sensitivity, and may have the problem of false detection, which may lead to the inaccurate test results. This paper presents a high sensitivity liquid level detection system based on the principle of variable capacitance. When the sampling probe contacts the liquid level, the probe capacitance will change. The liquid level detection circuit board judges whether the probe contacts the liquid level by sensing the change of probe capacitance. When judging the liquid level signal, the combination of slope detection and amplitude detection is used. The liquid level detection circuit board takes the phase-locked loop(PLL) circuit as the center to detect the change of the capacitance. The reference signal of the PLL is set as a square wave of 375kHz. The double tube probe is used as a part of the tuning capacitor of the voltage controlled oscillator to control the frequency of the output signal, which can realize the rapid phase locking. The experimental results show that the system has accurate detection results, high sensitivity, stable and reliable operation, good dynamic response performance in the case of large and small liquid volume. Compared with other liquid level detection methods based on machine vision, ultrasonic, optics and so on, the proposed liquid level detection system has simpler structure and lower cost, it can avoid the problems of collision, carryover contamination and empty suction by controlling the depth of sampling needle inserted into liquid.

Intravenous thrombolysis for acute ischemic stroke during two COVID-19 outbreaks in China: Wuhan pandemic and Beijing pandemic.

INTRODUCTION: The COVID-19 pandemic has had an impact on the emergency department (ED). Door-to-needle time (DNT) could be prolonged for intravenous thrombolysis (IVT) treatment. We aimed to investigate the impact of two COVID-19 pandemics on the workflow of IVT in our neurovascular ED. METHOD: We performed a retrospective analysis of patients who received IVT treatment in the neurovascular ED of Beijing Tiantan Hospital, Beijing, from January 20, 2020, to October 30, 2020, covering two COVID-19 pandemics in China. The time-based performances of IVT treatment including onset-to-arrival time, arrival-to-CT time, CT-to-needle time, door-to-needle time, and onset-to-needle time were recorded. Data on clinical characteristics and imaging information were also collected. RESULTS: Four hundred forty patients that received IVT were enrolled in this study. The number of patients admitted to our neurovascular ED began to decrease in December 2019 and was the lowest in April 2020 (n = 95). Longer DNT (Wuhan pandemic: 49.00 [35.00, 64.00] min; Beijing pandemic: 55.00 [45.50, 77.00] min) interval delays were observed during the two pandemics (p = .016). More patients admitted during the two pandemics had an 'unknown' subtype (Wuhan pandemic: 21.8%; Beijing pandemic: 31.4%. p = .008). The percentage of the cardiac embolism subtype was higher during the Wuhan pandemic (20.0%) than during other periods. The median admission NIHSS score increased during the Wuhan pandemic and the Beijing pandemic (8.00 [4.00, 12.00], 7.00 [4.50, 14.00], respectively, p < .001). CONCLUSION: The number of patients who received IVT decreased during the Wuhan pandemic. Higher admission NIHSS scores and prolonged DNT intervals were also observed during the Wuhan pandemic and the Beijing pandemic.

Trial of Endovascular Therapy for Acute Ischemic Stroke with Large Infarct.

BACKGROUND: The role of endovascular therapy for acute stroke with a large infarction has not been extensively studied in differing populations. METHODS: We conducted a multicenter, prospective, open-label, randomized trial in China involving patients with acute large-vessel occlusion in the anterior circulation and an Alberta Stroke Program Early Computed Tomography Score of 3 to 5 (range, 0 to 10, with lower values indicating larger infarction) or an infarct-core volume of 70 to 100 ml. Patients were randomly assigned in a 1:1 ratio within 24 hours from the time they were last known to be well to undergo endovascular therapy and receive medical management or to receive medical management alone. The primary outcome was the score on the modified Rankin scale at 90 days (scores range from 0 to 6, with higher scores indicating greater disability), and the primary objective was to determine whether a shift in the distribution of the scores on the modified Rankin scale at 90 days had occurred between the two groups. Secondary outcomes included scores of 0 to 2 and 0 to 3 on the modified Rankin scale. The primary safety outcome was symptomatic intracranial hemorrhage within 48 hours after randomization. RESULTS: A total of 456 patients were enrolled; 231 were assigned to the endovascular-therapy group and 225 to the medical-management group. Approximately 28% of the patients in both groups received intravenous thrombolysis. The trial was stopped early owing to the efficacy of endovascular therapy after the second interim analysis. At 90 days, a shift in the distribution of scores on the modified Rankin scale toward better outcomes was observed in favor of endovascular therapy over medical management alone (generalized odds ratio, 1.37; 95% confidence interval, 1.11 to 1.69; P = 0.004). Symptomatic intracranial hemorrhage occurred in 14 of 230 patients (6.1%) in the endovascular-therapy group and in 6 of 225 patients (2.7%) in the medical-management group; any intracranial hemorrhage occurred in 113 (49.1%) and 39 (17.3%), respectively. Results for the secondary outcomes generally supported those of the primary analysis. CONCLUSIONS: In a trial conducted in China, patients with large cerebral infarctions had better outcomes with endovascular therapy administered within 24 hours than with medical management alone but had more intracranial hemorrhages. (Funded by Covidien Healthcare International Trading [Shanghai] and others; ANGEL-ASPECT ClinicalTrials.gov number, NCT04551664.).

A novel risk score to predict deep vein thrombosis after spontaneous intracerebral hemorrhage.

Background and purpose: Studies showed that patients with hemorrhagic stroke are at a higher risk of developing deep vein thrombosis (DVT) than those with ischemic stroke. We aimed to develop a risk score (intracerebral hemorrhage-associated deep vein thrombosis score, ICH-DVT) for predicting in-hospital DVT after ICH. Methods: The ICH-DVT was developed based on the Beijing Registration of Intracerebral Hemorrhage, in which eligible patients were randomly divided into derivation (60%) and internal validation cohorts (40%). External validation was performed using the iMCAS study (In-hospital Medical Complication after Acute Stroke). Independent predictors of in-hospital DVT after ICH were obtained using multivariable logistic regression, and ß-coefficients were used to generate a scoring system of the ICH-DVT. The area under the receiver operating characteristic curve (AUROC) and the Hosmer-Lemeshow goodness-of-fit test were used to assess model discrimination and calibration, respectively. Results: The overall in-hospital DVT after ICH was 6.3%, 6.0%, and 5.7% in the derivation (n = 1,309), internal validation (n = 655), and external validation (n = 314) cohorts, respectively. A 31-point ICH-DVT was developed from the set of independent predictors including age, hematoma volume, subarachnoid extension, pneumonia, gastrointestinal bleeding, and length of hospitalization. The ICH-DVT showed good discrimination (AUROC) in the derivation (0.81; 95%CI = 0.79-0.83), internal validation (0.83, 95%CI = 0.80-0.86), and external validation (0.88; 95%CI = 0.84-0.92) cohorts. The ICH-DVT was well calibrated (Hosmer-Lemeshow test) in the derivation (P = 0.53), internal validation (P = 0.38), and external validation (P = 0.06) cohorts. Conclusion: The ICH-DVT is a valid grading scale for predicting in-hospital DVT after ICH. Further studies on the effect of the ICH-DVT on clinical outcomes after ICH are warranted.

Identification of protein biomarkers in host cerebrospinal fluid for differential diagnosis of tuberculous meningitis and other meningitis.

Background and purpose: The diagnosis of tuberculous meningitis (TBM) is difficult due to the lack of sensitive methods. Identification of TBM-specific biomarkers in the cerebrospinal fluid (CSF) may help diagnose and improve our understanding of TBM pathogenesis. Patients and methods: Of the 112 suspected patients with TBM prospectively enrolled in the study, 32 patients with inconclusive diagnosis, non-infectious meningitis, and long-term treatment with hormones and immunosuppressants were excluded. The expression of 8 proteins in the CSF was analyzed using ELISA in 22 patients with definite TBM, 18 patients with probable TBM, and 40 patients with non-TBM. Results: Significant differences in the expression of 7 proteins were detected between the TBM and non-TBM groups (P < 0.01). Unsupervised hierarchical clustering (UHC) analysis revealed a disease-specific profile consisting of 7 differentially expressed proteins for TBM diagnosis, with an accuracy of 82.5% (66/80). Logistic regression with forward stepwise analysis indicated that a combination of 3 biomarkers (APOE_APOAI_S100A8) showed a better ability to discriminate TBM from patients with non-TBM [area under the curve (AUC) = 0.916 (95%CI: 0.857-0.976)], with a sensitivity of 95.0% (95%CI: 83.1-99.4%) and a specificity of 77.5% (95%CI: 61.5-89.2%). Conclusion: Our results confirmed the potential ability of CSF proteins to distinguish TBM from patients with non-TBM and provided a useful panel for the diagnosis of TBM.

Comparison of clinical scores for predicting stroke-associated pneumonia after intracerebral hemorrhage (ICH): potential tools for personalized care and clinical trials for ICH.

Background: This study aimed to systematically compare the discrimination and calibration of 5 clinical scores for stroke-associated pneumonia (SAP) after intracerebral hemorrhage (ICH). Methods: We derived a validation cohort from the Beijing Registration of Intracerebral Hemorrhage. SAP was then diagnosed according to the Center for Disease Control and Prevention's criteria for hospital-acquired pneumonia. The area under the receiver operating characteristic curve (AUROC) and Hosmer-Lemeshow goodness-of-fit test were used to assess model discrimination and calibration. Results: A total of 1964 patients were enrolled in the study. The mean age was 56.8±14.4 years, and 67.6% were male. The median National Institutes of Health Stroke Scale (NIHSS) score at admission was 11 [interquartile range (IQR), 3-21], while the median length of stay (LOS) was 16 days (IQR, 8-22 days). A total of 575 (29.2%) patients were diagnosed with in-hospital SAP after ICH. The AUROC of the 5 clinical scores ranged from 0.732 to 0.800. In comparing these scores, we found that the ICH-associated pneumonia score-B (ICH-APS-B 0.800; 95% CI: 0.780-0.820; P<0.001) showed a statistically better discrimination than did the other risk models (all P<0.001). Furthermore, all clinical scores performed better in patients with an LOS >72 h. The ICH-APS-B (0.827; 95% CI: 0.806-0.848; P<0.001) still showed statistically better discrimination than did the other risk models in patients with an LOS longer than 72 hours. The Hosmer-Lemeshow test also revealed that the ICH-APS-B. had the largest Cox and Snell R2 result for in-hospital SAP after ICH. Conclusions: Among the 5 models for predicting SAP after ICH, the ICH-APS-B showed the best predictive performance, suggests it may be a useful tool for implementing the personalized care of patients and conducting clinical trials of SAP after ICH.

Head-to-head comparison of prognostic models of spontaneous intracerebral hemorrhage: tools for personalized care and clinical trial in ICH.

To systematically compare 27 ICH models with regard to mortality and functional outcome at 1-month, 3-month and 1-year after ICH. The validation cohort was derived from the Beijing Registration of Intracerebral Hemorrhage. Poor functional outcome was defined as modified Rankin Scale score (mRS) ≥3 at 1-month, 3-month and 1-year after ICH, respectively. The area under the receiver operating characteristic curve (AUROC) and Hosmer-Lemeshow goodness-of-fit test were used to assess model discrimination and calibration. A total number of 1575 patients were included. The mean age was 57.2 ± 14.3 and 67.2% were male. The median NIHSS score on admission was 11 (IQR: 3-21). For predicting mortality at 3-month after ICH, AUROC of 27 ICH models ranged from 0.604 to 0.856. In pairwise comparison, the ICH-FOS (0.856, 95%CI = 0.835-0.878, P < 0.001) showed statistically better discrimination than other models for mortality at 3-month after ICH (all P < 0.05). For predicting poor functional outcome (mRS≥3) at 3-month after ICH, AUROC of 27 ICH models ranged from 0.602 to 0.880. In pairwise comparison with other prediction models, the ICH-FOS was superior in predicting poor functional outcome at 3-month after ICH (all P < 0.001). The ICH-FOS showed the largest Cox and Snell R-square. Similar results were verified for mortality and poor functional outcome at 1-month and 1-year after ICH. Several risk models are externally validated to be effective for risk stratification and outcome prediction after ICH, especially the ICH-FOS, which would be useful tools for personalized care and clinical trial in ICH.

Using the Diaphragm as a Tracking Surrogate in CyberKnife Synchrony Treatment.

BACKGROUND In this study, we assessed the usefulness of diaphragm surrogate tracking in the design of a respiratory model for CyberKnife Synchrony treatment of lung tumors. MATERIAL AND METHODS Twenty-four patients with lung cancer who underwent stereotactic body radiotherapy with CyberKnife between April and November 2019 were enrolled. Simulation plans for each patient were designed using Xsight lung tracking (XLT) and diaphragm tracking (DT) methods, and tumor visualization tests were performed. The offset consistency at each respiratory phase was analyzed. The relative distance along the alignment center of the superior-inferior (SI) axis in the 2 projections (dxAB), uncertainty (%), and average standard error (AvgStdErr)/maximum standard error (MAXStdErr) were also analyzed. RESULTS Bland-Altman analyses revealed that the average differences±standard deviation (SD) between XLT and DT tracking methods were 0.4±2.9 mm, 0.3±4.35 mm, and -1.8±6.8 mm for the SI, left-right (LR), and anterior-posterior (AP) directions, respectively. These results indicated high consistency in the SI and LR directions and poor consistency in the AP direction. Uncertainty differed significantly between XLT and DT (22.813±5.721% vs 9.384±3.799%; t=-5.236; P=0.0008), but we found no significant differences in dxAB, AvgStdErr, or MAXStdErr. CONCLUSIONS In the majority of cases, motion tracking by XLT and DT was consistent and synchronized in the SI directions, but not in the LR and AP directions. With a boundary margin of 0.3±4.35 mm and 1.8±6.8 mm for the LR and AP directions, DT may contribute to better implementation of CyberKnife Synchrony treatment in patients with lung tumors near the diaphragm that cannot be seen in tumor visualization tests.

Diagnostic accuracy of Xpert MTB/RIF Ultra for tuberculous meningitis in a clinical practice setting of China.

A comparative performance evaluation of the novel Xpert MTB/RIF Ultra (Xpert Ultra) and MTB/RIF Xpert (Xpert) for tuberculous meningitis (TBM) diagnosis was performed. The cerebrospinal fluids of suspected TBM patients were collected consecutively and subjected to smear microscopy, culture, Xpert, and Xpert Ultra. In total, 160 patients were recruited. Xpert Ultra produced a higher sensitivity (45%, 34 of 76) than Xpert (28%, 21 of 76; P = 0.001) and culture (18%, 14 of 76; P < 0.001), respectively. Inclusion of Xpert Ultra outcomes increased the percentage of definite TBM case from 36% (27 of 76) to 51% (39 of 76). Both Xpert Ultra and Xpert accurately identified the one rifampicin (RIF)-resistant and the 5 RIF-sensitive cases defined by phenotypic drug sensitivity test. The specificities of all of the culture, Xpert and Xpert Ultra were 100% (45 of 45). Xpert Ultra outperformed both Xpert and culture for TBM diagnosis, which may speed up the appropriate treatment of patients in clinical practice.

Genome-Wide miRNA Analysis Identifies Potential Biomarkers in Distinguishing Tuberculous and Viral Meningitis.

Tuberculous meningitis (TBM) is the most common and severe form of central nervous system tuberculosis. Due to the non-specific clinical presentation and lack of efficient diagnosis methods, it is difficult to discriminate TBM from other frequent types of meningitis, especially viral meningitis (VM). In order to identify the potential biomarkers for discriminating TBM and VM and to reveal the different pathophysiological processes between TBM and VM, a genome-wide miRNA screening of PBMCs from TBM, VM, and healthy controls (HCs) using microarray assay was performed (12 samples). Twenty-eight differentially expressed miRNAs were identified between TBM and VM, and 11 differentially expressed miRNAs were identified between TBM and HCs. The 6 overlapping miRNAs detected in both TBM vs. VM and TBM vs. HCs were verified by qPCR analysis and showed a 100% consistent expression patterns with that in microarray test. Statistically significant differences of 4 miRNAs (miR-126-3p, miR-130a-3p, miR-151a-3p, and miR-199a-5p) were further confirmed in TBM compared with VM and HCs in independent PBMCs sample set (n = 96, P < 0.01). Three of which were also showed significantly different between TBM and VM in CSF samples (n = 70, P < 0.05). The receiver operating characteristic curve (ROC) analysis showed that the area under the ROC curve (AUC) of these 4 miRNAs in PBMCs were more than 0.70 in discriminating TBM from VM. Combination of these 4 miRNAs could achieve better discriminative capacity [AUC = 0.893 (0.788-0.957)], with a sensitivity of 90.6% (75.0-98.0%), and a specificity of 86.7% (69.3-96.2%). Additional validation was performed to evaluate the diagnostic panel in another independent sample set (n = 49), which yielded a sensitivity of 81.8% (9/11), and specificity of 90.0% (9/10) in distinguishing TBM and VM, and a sensitivity of 81.8% (9/11), and a specificity of 84.6% (11/13) in discriminating TBM from other non-TBM patients. This study uncovered the miRNA profiles of TBM and VM patients, which can facilitate better understanding of the pathogenesis involved in these two diseases and identified 4 novel miRNAs in distinguishing TBM and VM.

A Comparison of Brain Death Criteria between China and the United States.

BACKGROUND: Criteria for determining brain death (BD) vary between China and the United States. We reported the results of an investigation designed to compare procedures to determine BD in two countries. METHODS: The latest criteria in the United states were published in 2010. The latest criteria in China were published in 2009. We used these two types of BD criteria to evaluate patients who were considered to be BD. The time, cost, and accuracy of the diagnosis were compared. RESULTS: From January 1, 2012 to October 8, 2013, there were 37 patients which were applied for BD evaluation in the Neurological Intensive Care Unit of Beijing Tiantan Hospital. The cause of coma were known as subarachnoid hemorrhage (18 patients, 48.6%), intracerebral hemorrhage (8 patients, 21.6%), cerebral ischemia (9 patients, 24.3%), brain stem tumor (1 patient, 2.7%), and intracranial infection (1 patient, 2.7%). The clinical examinations were done for all of the patients except 1 patient who had low blood pressure. Three patients had brainstem reflexes that were excluded from BD. Twenty-five patients had apnea tests, and 20 tests were completed that were all positive. Confirmatory tests were completed differently: Transcranial Doppler (30 patients, positive rate 86.7%), electroencephalogram (25 patients, positive rate 100%), and somatosensory evoked potential (16 patients, positive rate 100%). Thirty-three patients were diagnosed BD by criteria of the United States. Only 9 patients were diagnosed BD by Chinese criteria. The use of time and money in the USA criteria was obviously fewer than those in Chinese criteria (P = 0.000). CONCLUSION: Compared with BD criteria of the United States, Chinese criteria were stricter, lower positive rate, more cost in money and time, and more reliable by families and doctors.

Reference value of long-time exercise test in the diagnosis of primary periodic paralysis.

BACKGROUND: The long-time exercise test (ET) is used to diagnose the primary periodic paralyses (PPs). However the reference values of ET are many and various. This study aimed to investigate the reference value of long-time ET in the diagnosis of PPs. METHODS: We recruited 108 healthy subjects, 68 patients with PPs, and 72 patients with other diseases for the study. The procedure of ET was made on the basis of the McManis' method. Electrical responses were recorded from right abductor digiti minimi (ADM) muscle when stimulation of the ulnar nerve at the wrist. After the compound muscle action potential (CMAP) was monitored, subjects were then asked to contract the muscle as strongly as possible for 5 minutes. CMAPs were recorded for 2 seconds immediately after cessation of exercise, then every 5 minutes for 10 minutes, and finally every 10 minutes for 50 minutes. In general, the CMAP amplitudes will fall below the pre-exercise levels in an hour. The largest decrease was calculated and used as results of ET. RESULTS: The CMAP amplitude decreases had no significant differences between groups when the healthy adults were grouped according to age, gender, height, weight and test time. Decreases in PPs patients (57.76%) were significantly more than in healthy subjects (15.21%) and other disease patients (18.10%, P < 0.001). Receiver operating characteristic (ROC) curve analysis showed that the best threshold is 35.50%. CONCLUSIONS: In the long-time exercise test, threshold of 35.50% for the CMAP amplitude decrease was identified for abnormal. The result is not influenced by age, gender, height, weight, and test time. About 7.4% of healthy subjects were abnormal in ET.

F-wave latencies in patients with diabetes mellitus.

INTRODUCTION: To evaluate the sensitivity of electrophysiologic assessments, we compared F-waves and motor and sensory nerve conduction studies (MNCS and SNCS) in patients with diabetes mellitus (DM). METHODS: We tested median, ulnar, tibial, and fibular nerves in 132 DM patients divided into those with and without clinical evidence of polyneuropathy. RESULTS: Of 64 asymptomatic patients, 2 (3%) had MNCS or SNCS abnormalities, both of whom had F-wave changes, whereas 21 (33%) had only delayed F-waves, for a combined yield of 23 (36%). The corresponding values for 68 symptomatic patients consisted of 43 (63%), 14 (21%), and 57 (84%). In both groups, F-wave latency had a higher (P<0.05) frequency of abnormality than MNCS in all nerves. F-wave study also surpassed SNCS in lower limb nerves. CONCLUSIONS: F-waves of the tibial and fibular nerves are the most sensitive measure to detect subclinical or overt diabetic polyneuropathy. Muscle Nerve 49: 804-808, 2014.

Normative data of F-wave measures in China.

OBJECTIVE: To establish normal ranges of F-wave measures in China as compared to published data in Brazil and Japan. METHOD: We studied F waves in 127 healthy Chinese subjects, aged 21-78 years old, stimulating the median, ulnar, tibial and peroneal nerves distally and proximaly. RESULT: The F-wave latencies had a linear correlation to the subject height in all nerves tested, showing a steeper (P < 0.05) regression line in Brazil compared to China and Japan for the tibial nerve. The Chinese population also had a higher distally elicited F-wave persistence and faster F wave conduction velocities than previously reported for both ulnar and tibial nerves. These values showed significant difference (P < 0.05) compared to Brazil but not to Japan. CONCLUSION: F-wave latencies show a linear correlation to subject height, although the slope of regression lines varies among countries, reflecting the difference in F-wave persistence and F-wave conduction velocity. SIGNIFICANCE: Our study provides a rational for the use of a latency-height nomogram in clinical studies and underscores the importance of developing country specific normative data.

Thrombolysis with alteplase for acute ischemic stroke patients with atrial fibrillation.

OBJECTIVE: Intravenous administration of recombinant tissue plasminogen activator (rtPA) is known as the only approved treatment for acute ischemic stroke. However, it is still controversial whether acute ischemic stroke patients with atrial fibrillation should receive rtPA therapy. METHODS: We studied 99 patients altogether who belonged to three different groups based on the patient characteristics: (1) atrial fibrillation rtPA-treated group consisting of 22 ischemic stroke patients with atrial fibrillation treated with rtPA within 4.5 hours after the onset of stroke; (2) atrial fibrillation non-rtPA-treated group consisting of 44 acute ischemic stroke patients with atrial fibrillation matching in age and baseline National Institutes of Health Stroke Scale (NIHSS); (3) the non-atrial fibrillation rtPA-treated group consisting of 33 patients without atrial fibrillation treated with rtPA. RESULTS: The median time for the administration of rtPA was 199.6 +/- 50.0 minutes. More patients had favorable outcomes (90 day modified Rankin Scale 0-1) in the atrial fibrillation rtPA-treated group than the atrial fibrillation non-rtPA-treated group (36.4 versus 13.6%; odds ratio=2.667; 95% confidence interval: 1.056-6.735; p=0.033). The mortality at day 90 was lower in the rtPA-treated group than the non-rtPA-treated group (18.2 versus 20.5%; p=0.827), although the incidence of symptomatic intracranial hemorrhage was higher (18.2 versus 6.8%; p=0.184). Patients in the atrial fibrillation rtPA-treated group had fewer favorable outcomes than non-atrial fibrillation rtPA-treated group (36.4 versus 51.6%; p=0.076), but their baseline NIHSS was higher (12.0 +/- 7.1 versus 9.1 +/- 7.3; p=0.161). CONCLUSION: As compared with non-rtPA-treated patients, rtPA treated within 4.5 hours after the onset of stroke significantly improved clinical outcomes in atrial fibrillation patients. Thrombolytic treatment increases intracranial hemorrhage rate but does not increase mortality.