Single-cell profiling identifies T cell subsets associated with control of tuberculosis dissemination.

To identify T cell subsets associated with control of tuberculosis, single-cell transcriptome and T cell receptor sequencing were performed on total T cells from patients with tuberculosis and healthy controls. Fourteen distinct subsets of T cells were identified by unbiased UMAP clustering. A GZMK-expressing CD8+ cytotoxic T cell cluster and a SOX4-expressing CD4+ central memory T cell cluster were depleted, while a MKI67-expressing proliferating CD3+ T cell cluster was expanded in patients with tuberculosis compared with healthy controls. The ratio of Granzyme K-expressing CD8+CD161-Ki-67- and CD8+Ki-67+ T cell subsets was significantly reduced and inversely correlated with the extent of TB lesions in patients with TB. In contrast, ratio of Granzyme B-expressing CD8+Ki-67+ and CD4+CD161+Ki-67- T cells and Granzyme A-expressing CD4+CD161+Ki-67- T cells were correlated with the extent of TB lesions. It is concluded that granzyme K-expressing CD8+ T cell subsets might contribute to protection against tuberculosis dissemination.

A New Type of Air Conditioning System Based on Finned Ceiling Radiant Coupled with Independent Fresh Air and Its Thermal Comfort Experimental Study.

The traditional radiation air conditioning system has some problems, such as easy condensation, insufficient refrigeration capacity, complex structure, and control system. Therefore, this study proposes a new type of finned metal radiant plate with large heat flow per unit area, sufficient cooling capacity, and simplified heat exchange system, in order to realize large temperature difference between cooling and heating. The temperature field uniformity and thermal comfort test of a novel type of finned ceiling radiant panel and independent fresh air linked air conditioning system under summer cooling and winter heating circumstances are accomplished through artificially generated climate environments. The study's findings demonstrate that in the radiation and fresh air modes, the maximum interior temperature differential under cooling conditions does not rise over 2.1°C. The maximum temperature differential in the space at any one moment in the radiation and fresh air modes cannot be greater than 3°C when heating conditions are present. The fresh air's cooling and dehumidifying effects are clear. The dehumidification efficiency may reach 50%, and the moisture content ranges from 5.48 to 9.63 g/kg. With PMV ranging from -0.34 to 0.54, the enhanced air conditioning system in this research provides exceptionally good thermal comfort. Additionally, the finned radiant panel's installation area occupies just 14% of the ceiling, which is sufficient to fulfill the room's cooling and heating load needs as well as provide high thermal comfort and consistent indoor temperature. The theoretical investigation and practical implementation of the direct expansion radiant air conditioning system are both strongly supported by this research.

Mesenchymal-epithelial Transition Factor Regulates Monocyte Function during Mycobacterial Infection via Indoleamine 2,3-dioxygenase.

OBJECTIVE: Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), causes an estimated 1.6 million human deaths annually, but the pathogenesis of TB remains unclear. Immunity plays a critical role in the onset and outcome of TB. This study aimed to uncover the roles of innate and adaptive immunity in TB. METHODS: The gene expression profiles generated by RNA sequencing from human peripheral blood mononuclear cells (PBMCs) stimulated with or without Mtb strain H37Rv antigens were analyzed. A total of 973 differentially expressed mRNAs were identified. RESULTS: The differentially expressed genes were enriched in innate immunity signaling functions. The mesenchymal-epithelial transition factor (MET) gene was significantly upregulated in CD14+ monocytes. A MET inhibitor improved the uptake of the BCG strain by monocytes and macrophages as well as inhibited the expression of indoleamine 2,3-dioxygenase (IDO). The expression of IDO was increased in PBMCs stimulated with Mtb antigens, and the IDO inhibitor promoted the expression of CD40, CD83, and CD86. CONCLUSION: Our results might provide clues regarding the immunomodulatory mechanisms used by Mtb to evade the host defense system.

Left atrial appendage occlusion in a mirror-image dextrocardia: A case report and review of literature.

BACKGROUND: In mirror-image dextrocardia, the anterior-posterior position of the cardiac chambers and great vessels is maintained, but the left-right orientation of the abdominal organs is reversed. The abnormal anatomy of the heart poses surgical challenges and problems in dealing with surgical risk and monitoring complications. There are few reports on closure of the left atrial appendage (LAA) in dextrocardia and no reports on the application of enhanced recovery after surgery (ERAS) following LAA occlusion (LAAO) procedures. CASE SUMMARY: The objective for this case was to ensure perioperative safety and accelerate postoperative recovery from LAAO in a patient with mirror-image dextrocardia. ERAS was guided by the theory and practice of nursing care. Atrial fibrillation was diagnosed in a 77-year-old male patient, in whom LAAO was performed. The 2019 guidelines for perioperative care after cardiac surgery recommend that the clinical nursing procedures for patients with LAAO should be optimized to reduce the incidence of perioperative complications and ensure patient safety. Music therapy can be used throughout perioperative treatment and nursing to improve the anxiety symptoms of patients. CONCLUSION: The procedure was uneventful and proceeded without complications. Anxiety symptoms were improved.

PINCH1 knockout aggravates myocardial infarction in mice via mediating the NF-κB signaling pathway.

Myocardial infarction (MI), the leading cause of death among patients with cardiovascular diseases, is characterized by acute cardiac muscle injury due to severe impairment of the coronary blood supply, which may lead to cardiogenic shock and cardiac arrest. Particularly interesting new cysteine histidine rich 1 (PINCH1) protein, a key component of the integrin signaling pathway, interacts with several proteins and serves a vital role in numerous cellular processes, including cytoskeleton remodeling, cell proliferation and cell migration. To investigate the role of PINCH1 in heart injury in the present study, PINCH1 was knocked out in the myocardial tissue of mice (age, 18 weeks) to induce MI. In addition, cell viability, migration and apoptosis, as well as the expression levels of NF-κB-associated proteins were determined in murine HL1 cardiomyocytes with a conditional PINCH1 shRNA using Cell Counting Kit-8, Transwell, flow cytometry and western blot assays, respectively. Furthermore, the cardiac expansion and myocardial fibrosis in PINCH1 knockout mice was investigated in vivo by performing morphological and histological examinations. Additionally, the murine ventricular myocardial ultrastructure was evaluated using an electron microscope, and the cardiomyocyte apoptotic rate and expression levels of NF-κB-related proteins were determined using TUNEL and western blot assays, respectively. The results showed that the apoptotic rate in the in vivo PINCH1 knockdown group was significantly increased. In addition, the protein expression levels of NF-κB signaling pathway-related proteins, including NF-κB, myeloid differentiation factor 88, TNF-α and caspase-3, were significantly increased in the in vivo PINCH1 knockdown group compared with the wild-type group, but the protein expression of MMP2 and MMP9 were the opposite. Overall, the in vitro and in vivo results revealed that PINCH1 knockout in mice significantly aggravated MI via the NF-κB signaling pathway.

Atorvastatin protects cardiac progenitor cells from hypoxia-induced cell growth inhibition via MEG3/miR-22/HMGB1 pathway.

Heart failure (HF) induced by ischemia myocardial infarction (MI) is one of the major causes of morbidity and mortality all around the world. Atorvastatin, a hydroxymethylglutaryl coenzyme A reductase inhibitor, has been demonstrated to benefit patients with ischemic or non-ischemic-induced HF, but the mechanism is still poorly understood. Increasing evidence indicates that lncRNAs play important role in variety of human disease. However, the role and underlying molecular mechanisms remain largely unclear. In our work, we applied 0.5% O2 to generate a hypoxia cardiac progenitor cell (CPC) model. Then, CCK8 and EdU assays were employed to investigate the role of atorvastatin in hypoxia CPC cell model. We found that hypoxia inhibits CPC viability and proliferation through modulating MEG3 expression, while atorvastatin application can protect CPCs from hypoxia-induced injury through inhibiting MEG3 expression. Then, we demonstrated that repression of MEG3 inhibited the hypoxia-induced injury of CPCs and overexpression of MEG3 inhibited the protective effect of atorvastatin in the hypoxia-induced injury of CPCs. Furthermore, our study illustrated that atorvastatin played its role in CPC viability and proliferation by modulating the expression of HMGB1 through the MEG3/miR-22 pathway. Our study, for the first time, uncovered the molecular mechanism of atorvastatin's protective role in cardiomyocytes under hypoxia condition, which may provide an exploitable target in developing effective therapy drugs for MI patients.

Hypoxia induces hypomethylation of the HMGB1 promoter via the MAPK/DNMT1/HMGB1 pathway in cardiac progenitor cells.

Apoptosis is involved in the death of cardiac progenitor cells (CPCs) after myocardial infarction (MI) in the heart. The loss of CPCs results in infarct scar and further deterioration of the heart function. Though stem cell-based therapy provides an effective approach for heart function recovery after MI, the retention of CPCs in the infarcted area of the heart is the main barrier that limits its promising therapy. Therefore, the underlying mechanisms of CPC apoptosis in hypoxia are important for the development of new therapeutic targets for MI patients. In this work, we found that the expression of high-mobility group box 1(HMGB1) was upregulated in CPCs under hypoxia conditions. Further study demonstrated that HMGB1 was regulated by DNA methyltransferases 1 (DNMT1) via changing the methylation state of CpGs in the promoter of HMGB1 in CPCs during hypoxia process. Additionally, mitogen-activated protein kinase (MAPK) signaling pathway was found to be involved in regulating DNMT1/HMGB1-mediated CPC apoptosis in hypoxia process. In conclusion, our findings demonstrate a novel regulatory mechanism for CPC apoptosis and proliferation under hypoxia conditions, which may provide a new therapeutic approach for MI patients.

High-Sensitivity C-Reactive Protein Combined with Low-Density Lipoprotein Cholesterol as the Targets of Statin Therapy in Patients with Acute Coronary Syndrome.

To investigate the combination of high-sensitivity C-reactive protein (hs-CRP) and Low-density lipoprotein (LDL)-C as the targets for statin treatment in patients with acute coronary syndrome (ACS). This single-center, prospective, randomized study was performed in 400 patients treated with atorvastatin 40 mg/day for 1 month and then with atorvastatin 20 mg/day as maintenance. The patients were randomized to the LDL group (LDL-C target of < 2.07 mmol/L according to the Chinese dyslipidemia guidelines) and to the LDL-CRP group (LDL-C target of < 2.07 mmol/L and hs-CRP target of < 3 mg/L). The patients were followed up for major adverse cardiac events (MACE) at 6, 12, and 18 months. The two groups had similar baseline characteristics and 391 patients completed the follow-up. No differences were found in LDL-C between the two groups, but a difference was found in hs-CRP at 12 and 18 months. There was a significant difference in revascularization (8.7% versus 3.6%, P = 0.04) and MACE (16.8% versus 9.7%; P = 0.04) between the LDL and LDL-CRP groups at 18 months. Compared to LDL-C as the single target, targeting both LDL-C and hs-CRP by statin therapy in patients with ACS could further reduce the incidence of MACE and the residual cardiovascular risk.

[Down-regulated expression of c-Jun in peripheral blood mononuclear cells of patients with severe secondary pulmonary tuberculosis].

OBJECTIVE: To compare the expression of c-Jun in severe versus mild secondary pulmonary tuberculosis (TB) and understand the relationship of the c-Jun expression with the inflammation and immune injury of severe secondary TB patients. METHODS: Differentially expressed genes were screened in patients with severe TB, the ones with mild TB and healthy controls using Affymetrix human gene expression chips. Bioinformatic analysis was performed on the results of the gene chip screening. The relative transcript level of c-Jun was detected by real-time quantitative PCR (qRT-PCR). The protein expression of c-Jun in peripheral blood mononuclear cells was detected by ELISA. RESULTS: Patients with severe pulmonary TB exibited a large number of differentially expressed genes compared with healthy controls and patients with mild secondary TB, and these differential expressed genes involved complicated pathways of immue response and inflammation. C-Jun was down-regulated 2.27 times in the patients with severe secondary TB compared with the ones with mild TB, and it is involved in 61 pathways. The qRT-PCR verified that c-Jun was down-regulated significantly in the patients with severe secondary TB compared with the mild ones. ELISA confirmed the trend of down-regulation of c-Jun in the patients with severe secondary TB. The results of qRT-PCR and ELISA were consistent with gene chip analysis. CONCLUSION: C-Jun was down-regulated in the patients with severe secondary TB compared with the patients with mild TB, and it is involved in many pathways of immue response and inflammation. Its down-regulation might be related to the immune injury of severe secondary TB.

Mucosal-associated invariant T-cell function is modulated by programmed death-1 signaling in patients with active tuberculosis.

RATIONALE: Mucosal-associated invariant T (MAIT) cells have been proven to play an important role in host defense against mycobacterial infection in animal infection models; however, the functional role of MAIT cells in patients with active tuberculosis (TB) is still largely unknown. OBJECTIVES: To understand the clinical features and functions of MAIT cells in patients with active TB. METHODS: MAIT cells were analyzed in patients with pulmonary TB, tuberculous pleurisy, and tuberculous peritonitis by flow cytometry. The functions of MAIT cells were compared between patients with active TB and healthy control subjects. MEASUREMENTS AND MAIN RESULTS: The frequency of MAIT cells was significantly reduced both in peripheral blood from patients with active pulmonary TB (P < 0.0001) and in tuberculous pleural effusions compared with healthy control subjects but not in ascitic fluids from patients with tuberculous peritonitis. A comparison of bacillus Calmette-Guérin (BCG)-stimulated cytokine production showed that patients with active TB had significantly higher production of IFN-γ (P = 0.0034) and tumor necrosis factor (TNF)-α (P = 0.0399) compared with healthy control subjects. In contrast, when MAIT cells were stimulated with Escherichia coli, patients with active TB had significantly lower production of IFN-γ (P = 0.0007) and TNF-α (P = 0.0032). MAIT cells in patients with active TB exhibited elevated expression of programmed death-1 (PD-1) (P = 0.0015), and blockade of PD-1 signaling resulted in a significantly higher frequency of BCG-stimulated IFN-γ production in MAIT cells (P = 0.0178). CONCLUSIONS: MAIT-cell immune response to antigen stimulation in patients with active TB is regulated by PD-1, which could be a potential target for TB immunotherapy.

[Gene expression profiling and verification for severe secondary pulmonary tuberculosis patients].

OBJECTIVE: To explore the gene expression profiles of severe secondary pulmonary tuberculosis patients. METHODS: From May 2012 to October 2013, a total of 103 eligible patients with secondary pulmonary tuberculosis were recruited from Institution of Tuberculosis Research of PLA Hospital No. 309. They were divided into severe secondary pulmonary tuberculosis (severe group) (n = 57) and mild secondary pulmonary tuberculosis (mild group) (n = 46) by the severity of disease . At the same time age-matched healthy controls (n = 45) were selected from healthy subjects undergoing physical examination. Whole genome expression profiling was performed with Affymetrix Gene expression chips for 4 cases in severe group, 3 in mild group and 5 in healthy group. Cluster and bioinformatics analysies were performed on differentially expressed genes in severe versus mild group. The remainders of three groups were 53, 43 and 40 cases respectively used for verify the results of gene chip by real-time fluorescence quantitative PCR (RT-PCR). And 20 cases in severe group, 20 in mild group and 8 in control group were used to verify the expression level of jun oncogene (JUN) on behalf of differential expressed genes. Analysis of variance and non-parametric tests were used for statistic difference analysis among three groups. RESULTS: There were 406 differentially expressed genes for severe and mild groups. There were 264 down-regulated gene and 142 up-regulated ones. The down-regulated genes were predominant. Cluster analysis show the similarity of gene expression profile in the same group . The result confirmed that the gene chip experiments were both repeatable and reliable. According to gene ontology, the differentially expressed genes were mainly involved in such biological processes as immune response, signal transduction, regulation of transcription (DNA-dependent), inflammatory response, antigen processing and presentation and chemotaxis, etc. Pathway analysis showed differentially expressed genes were involved in 22 pathways of immune response and inflammation. The major pathways included B cell receptor signaling, antigen processing and presentation, Toll-like receptor signaling, MAPK signaling and transforming growth factor-beta (TGF-ß) signaling.Real-time fluorescence quantitative PCR (RT-PCR) analysis showed that the statistics of optical density for JUN was P < 0.001 in severe versus mild group. It was down-regulated in severe group. And the expression of JUN was conformed with the result of gene expression chip. CONCLUSIONS: The patients of severe group have a larger number of differential expressed genes versus those of mild group. And severe lung tissue damage in severe group may be correlated with differences in gene expression.

Practice of sedation and the perception of discomfort during mechanical ventilation in Chinese intensive care units.

PURPOSE: The purpose of this study was to investigate sedation practices and the perception of discomfort during mechanical ventilation in Chinese intensive care units (ICUs). MATERIAL AND METHOD: A prospective, observational, cohort study was conducted in 31 Chinese ICUs in academic hospitals from June 15 to August 15, 2006. Conscious patients who were discharged from the ICU after mechanical ventilation were consecutively included. Using a standardized questionnaire, a personal interview was conducted with each patient within 2 days after discharge from the ICU. Patients were asked about recollections of emotional and physical discomfort. Sedation and analgesia administration data were collected from patient records. RESULTS: As prospectively defined, 83 (50.9%) of 163 patients met criteria for complex-mixed discomfort (ie, at least 1 emotional and 2 physical disturbances). Similarly, 79.1% of patients remembered seriously uncomfortable experiences associated with 1 of the 3 predefined sources. Both protocolized sedation and continuous sedation without a defined protocol, but not intermittent sedation, significantly reduced the relative risk of complex-mixed discomfort occurrences (P < .001). Notably, only 14.7% of patients received protocolized sedation, and 61 (37.4%) of 163 were not given any sedatives. CONCLUSION: Mechanically ventilated ICU patients in Chinese academic hospitals were inadequately treated for discomfort. Protocolized sedation can effectively improve patient comfort.

[Relationship between severity of illness and mental status in ICU conscious patients: a nationwide multi-center clinical study].

OBJECTIVE: To survey the incidence of psychological adverse events in critical conscious patients during their ICU stay and analyze the relationship between the incidence and the severity of illness. METHODS: 234 conscious patients, 133 males and 101 females, aged (55.4 +/- 19.6), 80 with internal medicine diseases and 154 with surgical diseases, were treated in the ICUs of 31 grade 3 A hospitals over the country consecutively during the period of 2 months and then successfully transferred to other departments. The patients were interviewed with specific questionnaire within the 2 days after transfer to investigate the incidence of anxiety and depression and the tolerance of invasive medical and nursing procedures of the patients. RESULTS: The overall incidence of psychological adverse events (PAE) was 69.6%. Multi-variate Logistic analysis showed that acute physiology and chronic health evaluation (APACHE) II score was an independent high risk factor of PAE (OR = 1.07, 95% CI: 1.02-1.13, P < 0.05). The relative risk (RR) values of the patients with APACHE II scores 1-10, 11-20, and >20 were 1.29, 2.53, and 4. 85 respectively. The higher the APACHE II score, the more invasive interventions received (P < 0.01) , and the lower the mental stress threshold (P < 0.01) the higher the incidence of PAE (P < 0.01). The APACHE II scores of those who failed to tolerate noise and medical and nursing procedures were 15.8 +/- 5.7 and 16.5 +/- 6.1 respectively, both significantly higher than those of the patients who tolerated (12.1 +/- 4.4, P < 0.05; and 10.6 +/- 2.9, P < 0.01). CONCLUSION: APACHE II score is an independent high risk factor of PAE. The conscious ICU patients with higher APACHE II scores receive more invasive medical and nursing procedures. Low mental stress threshold greatly contributed to the incidence of PAE in ICU conscious critical patients with high APACHE II score.

[Midazolam attenuates mental stress in conscious patients during cardiopulmonary resuscitation performed next bed in intensive care unit].

OBJECTIVE: To evaluate the mental stress level and alterations in circulatory physiology in conscious patients during cardiopulmonary resuscitation (CPR) performed next bed in intensive care unit (ICU), and to investigate the possible effective interventions. METHODS: Eighty-seven conscious patients, selected consecutively from June 2003 to September 2006, were randomly allocated into control group (received normal saline), psychological nursing group (received psychological nursing intervention) or sedation group (received midazolam 0.1 mg/kg intravenous injection based on psychological nursing intervention) when CPR was performed in our ICU. Plasma concentrations of norepinephrine, epinephrine, cortisone and glucose were analyzed at the time points of beginning of CPR, 10 minutes, 4 and 24 hours after CPR in the first 40 patients. Heart rate (HR), systolic blood pressure (SBP), mean arterial pressure (MAP) and arrhythmia within 24 hours after CPR were recorded in all patients. RESULTS: Plasma levels of norepinephrine, epinephrine and cortisone were significantly increased at 10 minutes after CPR and persisted for 4 hours in 13 patients of the control group (P<0.05 or P<0.01). Though with the similar tendency, significant increase of cortisone level was observed in 13 patients who had received psychological nursing intervention (P<0.05 or P<0.01). The analyzed stress hormones showed little variation in 14 patients who were given midazolam at 10 minutes and 4 hours after CPR. Notably, 24 hours after CPR, they were decreased below the levels which were observed at the beginning of CPR (all P<0.01). Blood glucose levels were markedly higher in both control and psychological nursing groups than the level in sedation group within 24 hours. HR was accelerated 10 minutes after CPR, SBP was significantly increased, the incidence rate of arrhythmia was high (84.6%, 22/26; 54.5%, 18/33) in the non-sedation groups. Circulatory physiological alterations were least marked in sedation group (21.4%, 6/28, both P<0.01). CONCLUSION: Mental stress is significantly heightened in conscious patients during CPR performed next bed in ICU, and it induces severe circulatory physiological alterations. Psychological nursing alone is not affective in alleviating this acute mental stress. However, low dose of midazolam is found to be an effective intervention.

[Comparison of reliability of bispectral index and sedation-agitation scale in assessing the depth of sedation in patients treated with mechanical ventilation].

OBJECTIVE: To compare the reliability of bispectral index (BIS) with sedation agitation scale (SAS) in assessing the depth of sedation in ill patients on mechanical ventilation in intensive care unit (ICU). METHODS: Fifteen patients, aged 18-65 years old, who were receiving mechanical ventilation in ICU for longer than 72 hours and without brain dysfunction, were enrolled in this study. Sedatives and analgesics were suspended at 7:00 am. When patients fully woke up, propofol was infused till BIS score reaching 45-60. This was maintained for 10 minutes, then propofol dosage was decreased 10 microg . kg(-1) . min(-1) for every 10 minutes till all the drug was stopped. BIS was consecutively monitored and SAS was assessed in each interval. RESULTS: BIS score was markedly correlated with SAS (r=-0.6494, P<0.01). Although a significant correlation was still shown (r=-0.4566, P<0.01), there was wide variability in BIS scores when SAS reached 2-4. With decreasing of the propofol dosage, BIS score gradually increased. There was a satisfactory negative correlation between BIS scores and propofol dosage (r=-0.8076, P<0.01). SAS increased also following the decrease in propofol dosage, and a significant negative correlation was shown between SAS and the dosage of propofol (r=-0.6551, P<0.01). CONCLUSION: SAS is well correlated with BIS in assessing the depth of sedation in patients treated with mechanical ventilation in ICU. BIS is an objective, efficient tool for monitoring the depth of sedation in ICU critical patients who are receiving mechanical ventilation, and it is more reliable than SAS, especially when sedated levels reaching SAS 2-4.

[Study on safety of apnea test in clinical determination of brain death].

OBJECTIVE: To determine the occurrence of severe complications such as hypotension, pulmonary artery hypertension as well as hypercapnia during apnea test in the affirmation of brain death and to investigate the possible effective prophylactic interventions. METHODS: Conventional apnea test was performed in 15 clinically suspected brain death patients. Stable circulation was achieved by adjusting preload only (n=4) or combined with titrating norepinephrine (NE, n=11). Blood gas was respectively analyzed before apnea test, 10 minutes after 100% fraction of oxygen (FiO(2)) ventilation, at each 2-minute interval after disconnecting ventilator and 5 minutes after reventilation. Hemodynamic parameters and dosage of NE were recorded at the same time points. Plasma concentration of lactate was measured before and at the end of apnea test. RESULTS: Spontaneous breath occurred in 1 case among 15 suspected brain death patients. Partial pressure of carbon dioxide (PaCO(2)) reached higher than 60 mm Hg (1 mm Hg=0.133 kPa) within 8 minutes in positive apnea test patients (P<0.01). pH significantly decreased (P<0.05), but partial pressure of oxygen (PaO(2)) maintained higher than 100 mm Hg during the test. Heart rate (HR) and mean artery pressure (MAP) slightly lowered (P>0.05), but pulmonary artery pressure (PAP) markedly elevated (P<0.05) at the end of the test in comparison with their base lines. On the other hand, HR and MAP increased in the negative apnea test case after ventilator disconnection. Severe arrhythmia events did not occur in all the cases. There was no change in the dosage of NE infusion, the range of which was 0.10-0.60 microg.kg(-1).min(-1) with the mean level of (0.23+/-0.17) microg.kg(-1).min(-1). The trend of HR, MAP, PAP and pulmonary arterial wedge pressure (PAWP) alterations was the same in patients no matter whether or not NE was used. HR, MAP and PAWP lowered, while PAP enhanced. Plasma lactate level was not significantly altered at the end of the test compared with the base line (from (1.41+/-0.05) mmol/L to (1.47+/-0.07) mmol/L). CONCLUSION: Adequate oxygenation could be maintained during conventional apnea test. The risk of inducing severe hypotension is low in non brain death patients. Based on adequate preload, low dose of NE infusion could prevent patients with high risk circulation instability from severe hypotension.