AIM: To observe and analyze the effectiveness and safety of wearing corneal refractive therapy(CRT)and vision shaping treatment(VST)designed orthokeratology in controlling myopic progression in adolescents with low E-value corneal morphology.METHODS: This prospective study involved 100 cases(100 eyes)of adolescent myopia patients fitted with orthokeratology at our optometry clinic from January 2020 to December 2021. The data of right eye were collected for research, and they were divided into low myopia group(-1.00 to -3.00 D)and moderate myopia group(-3.25 to -5.00 D)according to spherical equivalent, with 50 cases in each group. Each group of patients was further randomly divided into the CRT group and the VST group, with 25 cases in each group. Uncorrected visual acuity, refractive error, axial length(AL), tear film break-up time(BUT), corneal endothelial cell density, corneal staining grading, lens decentration, and refractive power at 15°-30° were measured before and after wearing orthokeratology, with a follow-up duration of 1.5 a.RESULTS: The uncorrected visual acuity of CRT and VST subgroups in the low myopia group showed no statistical significance at any time point after wearing orthokeratology. However, in the moderate myopia group, CRT subgroup showed better uncorrected visual acuity than the VST subgroup, with significant differences at 1 d and 1 wk(t=-9.474, -12.067, both P<0.01); no significant differences were noted at other time points. After wearing lens for 6 mo and 1.5 a, the AL growth for the CRT subgroup in low and moderate myopia was less than the VST subgroup, with no statistically significant differences. There were no statistically significant differences in binocular BUT and corneal endothelial cell density after wearing lens for 6 mo and 1.5 a. Corneal injury was lower in the CRT subgroup than that in the VST subgroup, but the difference was not statistically significant(Z=-1.803, P=0.071). Lens decentration was significantly better in the CRT subgroup than in the VST subgroup(Z=-4.629, P<0.001). In the periphery of the retina at 15°-30°, there were no significant differences in the amount of myopic defocus between the two groups, while it was statistically significant at 1, 3, and 6 mo in the moderate myopia subgroup(t=-3.949, P=0.008; t=-5.833, P<0.001; t=-6.231, P<0.001), indicating that CRT subgroup could produce a greater amount of myopic defocus.CONCLUSION: For patients with low E-value corneal morphology, CRT, using the vector height at 8 mm on the cornea for fitting, is not limited to the corneal E-value. It shapes faster and improves uncorrected visual acuity after shaping, especially for moderate myopia, achieving better daytime vision. In terms of controlling myopia, CRT fitting elevates return zone depth(RZD), creating a small central optical zone to produce more peripheral myopic defocus. However, there was no significant difference between the two groups in controlling AL growth. Both groups showed minimal corneal damage, indicating consistent safety in myopia control.

OBJECTIVE: To investigate whether electroacupuncture (EA) at sensitized acupoints could reduce sympathetic-sensory coupling (SSC) and neurogenic inflammatory response by interfering with 5-hydroxytryptamine (5-HT)ergic neural pathways to relieve colitis and somatic referred pain, and explore the underlying mechanisms. METHODS: Rats were treated with 5% dextran sodium sulfate (DSS) solution for 7 days to establish a colitis model. Twelve rats were randomly divided into the control and model groups according to a random number table (n=6). According to the "Research on Rat Acupoint Atlas", sensitized acupoints and non-sensitized acupoints were determined. Rats were randomly divided into the control, model, Zusanli-EA (ST 36), Dachangshu-EA (BL 25), and Xinshu (BL 15) groups (n=6), as well as the control, model, EA, and EA + GR113808 (a 5-HT inhibitor) groups (n=6). The rats in the control group received no treatment. Acupuncture was administered on 2 days after modeling using the stimulation pavameters: 1 mA, 2 Hz, for 30 min, with sparse and dense waves, for 14 consecutive days. GR113808 was injected into the tail vein at 5 mg/kg before EA for 10 min for 7 consecutive days. Mechanical sensitivity was assessed with von Frey filaments. Body weight and disease activity index (DAI) scores of rats were determined. Hematoxylin and eosin staining was performed to observe colon histopathology. SSC was analyzed by immunofluorescence staining. Immunohistochemical staining was performed to detect 5-HT and substance P (SP) expressions. The calcitonin gene-related peptide (CGRP) in skin tissue and tyrosine hydroxylase (TH) protein levels in DRG were detected by Western blot. The levels of hyaluronic acid (HA), bradykinin (BK), prostaglandin I2 (PGI2) in skin tissue, 5-HT, tryptophan hydroxylase 1 (TPH1), serotonin transporters (SERT), 5-HT 3 receptor (5-HT3R), and 5-HT 4 receptor (5-HT4R) in colon tissue were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: BL 25 and ST 36 acupoints were determined as sensitized acupoints, and BL 15 acupoint was used as a non-sensitized acupoint. EA at sensitized acupoints improved the DAI score, increased mechanical withdrawal thresholds, and alleviated colonic pathological damage of rats. EA at sensitized acupoints reduced SSC structures and decreased TH and CGRP expression levels (P<0.05). Furthermore, EA at sensitized acupoints reduced BK, PGI2, 5-HT, 5-HT3R and TPH1 levels, and increased HA, 5-HT4R and SERT levels in colitis rats (P<0.05). GR113808 treatment diminished the protective effect of EA at sensitized acupoints in colitis rats (P<0.05). CONCLUSION EA at sensitized acupoints alleviated DSS-induced somatic referred pain in colitis rats by interfering with 5-HTergic neural pathway, and reducing SSC inflammatory response.
Rats ; Animals ; Electroacupuncture ; Rats, Sprague-Dawley ; Serotonin ; Acupuncture Points ; Pain, Referred ; Calcitonin Gene-Related Peptide ; Signal Transduction ; Colitis/therapy* ; Indoles ; Sulfonamides

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.

Objective:To investigate the value of transanal multipoint full-layer puncture biopsy (TMFP) in predicting pathological complete response (pCR) after neoadjuvant radiotherapy and chemotherapy (nCRT) in patients with locally advanced rectal cancer (LARC) and to establish a predictive model for providing clinical guidance regarding the treatment of LARC.Methods:In this multicenter, prospective, cohort study, we collected data on 110 LARC patients from four hospitals between April 2020 and March 2023: Beijing Chaoyang Hospital of Capital Medical University (50 patients), Beijing Friendship Hospital of Capital Medical University (41 patients), Qilu Hospital of Shandong University (16 patients), and Zhongnan Hospital of Wuhan University (three patients). The patients had all received TMFP after completing standard nCRT. The variables studied included (1) clinicopathological characteristics; (2) clinical complete remission (cCR) and efficacy of TMFP in determining pCR after NCRT in LARC patients; and (3) hospital attended, sex, age, clinical T- and N-stages, distance between the lower margin of the tumor and the anal verge, baseline and post-radiotherapy serum carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 concentrations, chemotherapy regimen, use of immunosuppressants with or without radiotherapy, radiation therapy dosage, interval between surgery and radiotherapy, surgical procedure, clinical T/N stage after radiotherapy, cCR, pathological results of TMFP, puncture method (endoscopic or percutaneous), and number and timing of punctures. Single-factor and multifactorial logistic regression analysis were used to determine the factors affecting pCR after NCRT in LARC patients. A prediction model was constructed based on the results of multivariat analysis and the performance of this model evaluated by analyzing subject work characteristics (ROC), calibration, and clinical decision-making (DCA) curves. pCR was defined as complete absence of tumor cells on microscopic examination of the surgical specimens of rectal cancer (including lymph node dissection) after NCRT, that is, ypT0+N0. cCR was defined according to the Chinese Neoadjuvant Rectal Cancer Waiting Watch Database Study Collaborative Group criteria after treatment, which specify an absence of ulceration and nodules on endoscopy; negative rectal palpation; no tumor signals on rectal MRI T2 and DWI sequences; normal serum CEA concentrations, and no evidence of recurrence on pelvic computed tomography/magnetic resonance imaging.Results:Of the 110 patients, 45 (40.9%) achieved pCR after nCRT, which was combined with immune checkpoint inhibitors in 34 (30.9%). cCR was diagnosed before puncture in 38 (34.5%) patients, 43 (39.1%) of the punctures being endoscopic. There were no complications of puncture such as enterocutaneous fistulae, vaginal injury, prostatic injury, or presacral bleeding . Only one (2.3%) patient had a small amount of blood in the stools, which was relieved by anal pressure. cCR had a sensitivity of 57.8% (26/45) for determining pCR, specificity of 81.5% (53/65), accuracy of 71.8% (79/110), positive predictive value 68.4% (26/38), and negative predictive value of 73.6% (53/72). In contrast, the sensitivity of TMFP pathology in determining pCR was 100% (45/45), specificity 66.2% (43/65), accuracy 80.0% (88/110), positive predictive value 67.2% (45/67), and negative predictive value 100.0% (43/43). In this study, the sensitivity of TMFP for pCR (100.0% vs. 57.8%, χ 2=24.09, P<0.001) was significantly higher than that for cCR. However, the accuracy of pCR did not differ significantly (80.0% vs. 71.8%, χ 2=2.01, P=0.156). Univariate and multivariate logistic regression analyses showed that a ≥4 cm distance between the lower edge of the tumor and the anal verge (OR=7.84, 95%CI: 1.48-41.45, P=0.015), non-cCR (OR=4.81, 95%CI: 1.39-16.69, P=0.013), and pathological diagnosis by TMFP (OR=114.29, the 95%CI: 11.07-1180.28, P<0.001) were risk factors for pCR after NCRT in LARC patients. Additionally, endoscopic puncture (OR=0.02, 95%CI: 0.05-0.77, P=0.020) was a protective factor for pCR after NCRT in LARC patients. The area under the ROC curve of the established prediction model was 0.934 (95%CI: 0.892-0.977), suggesting that the model has good discrimination. The calibration curve was relatively close to the ideal 45° reference line, indicating that the predicted values of the model were in good agreement with the actual values. A decision-making curve showed that the model had a good net clinical benefit. Conclusion:Our predictive model, which incorporates TMFP, has considerable accuracy in predicting pCR after nCRT in patients with locally advanced rectal cancer. This may provide a basis for more precisely selecting individualized therapy.

Objective To investigate the attributable risk(AR)of Acinetobacter baumannii(AB)infection in criti-cally ill patients.Methods A multicenter retrospective cohort study was conducted among adult patients in inten-sive care unit(ICU).Patients with AB isolated from sterile body fluid and confirmed with AB infection in each cen-ter were selected as the infected group.According to the matching criteria that patients should be from the same pe-riod,in the same ICU,as well as with similar APACHE Ⅱ score(±5 points)and primary diagnosis,patients who did not infect with AB were selected as the non-infected group in a 1:2 ratio.The AR was calculated.Results The in-hospital mortality of patients with AB infection in sterile body fluid was 33.3％,and that of non-infected group was 23.1％,with no statistically significant difference between the two groups(P=0.069).The AR was 10.2％(95％CI:-2.3％-22.8％).There is no statistically significant difference in mortality between non-infected pa-tients and infected patients from whose blood,cerebrospinal fluid and other specimen sources AB were isolated(P＞0.05).After infected with AB,critically ill patients with the major diagnosis of pulmonary infection had the high-est AR.There was no statistically significant difference in mortality between patients in the infected and non-infec-ted groups(P＞0.05),or between other diagnostic classifications.Conclusion The prognosis of AB infection in critically ill patients is highly overestimated,but active healthcare-associated infection control for AB in the ICU should still be carried out.

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-positive bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-positive bacteria from blood cultures in member hospitals of National Bloodstream Infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:A total of 3 163 strains of Gram-positive pathogens were collected from 51 member units，and the top five bacteria were Staphylococcus aureus（ n=1 147，36.3%），coagulase-negative Staphylococci（ n=928，29.3%）， Enterococcus faecalis（ n=369，11.7%）， Enterococcus faecium（ n=296，9.4%）and alpha-hemolyticus Streptococci（ n=192，6.1%）. The detection rates of methicillin-resistant Staphylococcus aureus（MRSA）and methicillin-resistant coagulase-negative Staphylococci（MRCNS）were 26.4%（303/1 147）and 66.7%（619/928），respectively. No glycopeptide and daptomycin-resistant Staphylococci were detected. The sensitivity rates of Staphylococcus aureus to cefpirome，rifampin，compound sulfamethoxazole，linezolid，minocycline and tigecycline were all >95.0%. Enterococcus faecium was more prevalent than Enterococcus faecalis. The resistance rates of Enterococcus faecium to vancomycin and teicoplanin were both 0.5%（2/369），and no vancomycin-resistant Enterococcus faecium was detected. The detection rate of MRSA in southern China was significantly lower than that in other regions（ χ2=14.578， P=0.002），while the detection rate of MRCNS in northern China was significantly higher than that in other regions（ χ2=15.195， P=0.002）. The detection rates of MRSA and MRCNS in provincial hospitals were higher than those in municipal hospitals（ χ2=13.519 and 12.136， P<0.001）. The detection rates of MRSA and MRCNS in economically more advanced regions（per capita GDP≥92 059 Yuan in 2022）were higher than those in economically less advanced regions（per capita GDP<92 059 Yuan）（ χ2=9.969 and 7.606， P=0.002和0.006）. Conclusions:Among the Gram-positive pathogens causing bloodstream infections in China， Staphylococci is the most common while the MRSA incidence decreases continuously with time；the detection rate of Enterococcus faecium exceeds that of Enterococcus faecalis. The overall prevalence of vancomycin-resistant Enterococci is still at a low level. The composition ratio of Gram-positive pathogens and resistant profiles varies slightly across regions of China，with the prevalence of MRSA and MRCNS being more pronounced in provincial hospitals and areas with a per capita GDP≥92 059 yuan.

Misuse of pyrrolizidine alkaloid (PA)-containing herbs is the major cause of hepatic sinusoidal obstruction syndrome (HSOS) in China. And diuretics are among the most commonly used medications for the treatment of PA-induced HSOS in clinical practice. As a traditional diuretic in traditional Chinese medicine, the diuretic mechanism of Alismatis Rhizoma (AR) has not been fully clarified, and there is no report on AR ameliorating PA-induced HSOS from a diuretic point of view. Therefore, this study aims to investigate the therapeutic potential of alisol B 23-acetate (AB23A) against acute liver injury induced by senecionine (a representative toxic PA) in mice, and to further elucidate its effect on impaired water-liquid balance in mice exposed to PA. All experiments were approved by the Animal Research Committee of Shanghai University of Traditional Chinese Medicine (Registration number: PZSHUTCM220808017). Animal welfare and the animal experimental protocols were strictly consistent with related ethics regulations of Shanghai University of Traditional Chinese Medicine. Model of mice was induced by a single oral exposure of senecioine (50 mg·kg^-1) (SEN group), and AB23A (40 mg·kg^-1) intervention group (AB23A+SEN group), solvent control group (Ctrl group) and AB23A control group (AB23A group) were set up. The results showed that AB23A could significantly attenuate the levels of serum biochemical indices of liver functions in senecioine-induced acute liver injury mice, as evident by alleviated hepatocyte necrosis and hepatic sinusoidal stasis. AB23A also improved kidney function of mice exposed to senecionine, fascinated urinary excretion and repaired electrolyte disorders, as well as decreased content of senecioine metabolites. Further, the protein and mRNA expression of genes related to the water balance pathway were measured. AB23A could significantly down-regulate the elevated protein and mRNA expression levels of aquaporin 2 (AQP2) and angiotensin II type 1 receptor, and inhibit the transport of AQP2 to the apical plasma membrane induced by senecionine exposure. AB23A also significantly decreased serum levels of angiotensin II. In vitro studies further confirmed that AB23A regulates AQP2 expression in renal inner medullary collecting duct cells 3 (IMCD3). These data indicate that AB23A regulates the expression of AQP2 in renal medulla, thereby affecting its water reabsorption in mice with senecionine-induced acute liver injury. This work achieves a better understanding of the diuretic effect of AR, and provides experimental foundation and theoretical basis for the treatment of PA-induced acute liver injury by AR in clinics.

Objective:To investigate the influencing of preoperative total bilirubin (TBil) on perioperative complications of hepatolithiasis receiving liver resection.Methods:The retrospective cohort study was conducted. The clinical data of 300 patients with hepatolithiasis who were admitted to 2 medical centers from January 2010 to January 2022 were collected. There were 115 males and 185 females, aged (54±13)years. Measurement data with normal distribution were represented as Mean± SD, and the independent sample t test was used for comparison between groups. Measurement data with skewed distribution were represented as M( Q1, Q3), and the Mann-Whitney U test was used for comparison between groups. Count data were expressed as absolute numbers, and the chi-square test was used for comparison between groups. Variables with P<0.10 in the univariate analysis were included into the multivariate analysis. Univariate analysis was conducted using the Logistic regression model,and multivariate analysis was conducted using the Logistic stepwise regression model with backward Wald method. Continuous variables were converted into categorical variables based on commonly reported cutoff values when conducting Logistic regression analysis. Results:(1) Comparison of clinical data of patients with different preoperative TBil. Of 300 patients with hepatolithiasis, there were 252 cases with low level of preoperative TBil as 14.4(11.1,19.7)μmol/L, and there were 48 cases with high level of preoperative TBil as 44.0(31.3,59.8)μmol/L. Of the pati-ents with low level of preoperative TBil, neutrophils percentage was 62%±10%, cases with intra-operative blood transfusion was 29, and cases undergoing anatomical liver resection was 166. Of the patients with high level of preoperative TBil, neutrophils percentage was 70%±11%, cases with intraoperative blood transfusion was 22, and cases undergoing anatomical liver resection was 15. There were significant differences in cases classified as>grade 2 of ASA classification, neutrophils percentage, cases with intraoperative blood transfusion and cases undergoing anatomical liver resection between patients with low and high level of preoperative TBil ( t=5.182, χ2=33.669, 18.775, P<0.05). (2) Comparison of perioperative complications of patients with different preoperative TBil. Of the 252 patients with low level of TBil, there were 151 cases with complications including 35 cases of serious complications, there was 1 case with postoperative liver failure, the duration of postoperative hospital stay was 13.0(10.0,16.0)days. Of the 48 patients with high level of TBil, there were 32 cases with complications including 17 cases of serious complications, there were 6 cases with postoperative liver failure, the duration of postoperative hospital stay was 14.0(10.0,18.8)days. There were significant differences in cases with serious complications and cases with postoperative liver failure between patients with low and high level of preoperative TBil ( χ2=13.041, 20.879, P<0.05). (3) Analysis of factors influencing postoperative serious complications in patients undergoing liver resection. Results of multivariate analysis showed that age, body mass index (BMI), preoperative TBil and volume of intraoperative blood loss were independent factors influencing postoperative serious complications in patients undergoing liver resection for hepatolithiasis ( odds ratio=3.852, 2.358, 2.935, 5.135, 95% confidence interval as 1.478?9.979, 1.110?5.009, 1.398?6.158, 2.088?12.626, P<0.05). Conclusions:Patients with high level of preoperative TBil have a significantly increased risk of postoperative serious complications and liver failure who receive liver resection for hepatolithiasis. Age, preoperative BMI, TBil and volume of intraoperative blood loss are independent factors influencing postoperative serious complications in patients undergoing liver resection for hepatolithiasis.

Objective To develop a portable medical oxygen purity analyzer capable of real-time detection of multi-compo-nent gases in medical oxygen or aviation oxygen to ensure the safety of oxygen consumption.Methods The portable medical oxygen purity analyzer with STM3F103RC as the main controller involved in a management module,an oxygen detection module,a carbon monoxide/chlorine detection module,a flow/carbon dioxide detection module and a dew point detection module as its hardware components,which had its human-machine interface programmed with DGUS supervision,control and data acquisition(SCADA)software and system program developed with C language under Keil MDK environment.The performance verification of the analyzer developed was carried out in terms of oxygen detection error and stability and errors for measuring carbon monoxide,chlorine and carbon dioxide.Results The analyzer showed high precision when used to detect oxygen with high volume fraction,with long-term stability and the absolute error restrained within±0.1％;the erros for measuring carbon monoxide,chlorine and carbon dioxide were all limited within±5％FS to meet the desired requirements.Condusion The portable medical oxygen purity analyzer developed with high precision,stability and portability can be used for detection of medical oxygen and aviation oxygen.[Chinese Medical Equipment Journal,2024,45(3):36-40]

Objective To develop a low-oxygen mixed gas generator to make up for the deficiencies of low-pressure chambers and load-resistant hypoxia trainers during pilot hypoxia tolerance testing.Methods The device prepared the low-oxygen gas with the principle of gas separation,which was composed of a Sunsource OLF1100D-220AF air compressor,a SMC IDG75SAM4-03 filter,a buffer tank,an AIR Products PA3010 integrated assembly,a control box,sensors and regulators.The sensors included the pressure sensor,flow sensor,concentration sensor and dew point temperature sensor,and the control box consisted of a main control board,a power supply module,a transmission module,a communication module,a display and a housing.The embedded control software of the device was developed with KEIL 5 and C++.Results The device developed prepared the low-oxygen gas with the volume fraction being 4％to 18％and the maximum error of volume fraction being 0.05％,and the main components of the prepared gas met the technical requirements of medical oxygen as stipulated in GB 8982-2009 Oxygen supplies for medicine and aircraft breathing.Conclusion The low-oxygen gas prepared by the device has its volume fraction precisely controlled and can be used for hypoxia tolerance testing and acclimation training for pilots.[Chinese Medical Equipment Journal,2024,45(7):24-28]