Oxygen Partial Pressure Difference Research Articles

Effect of dexmedetomidine on pulmonary function in obese patients undergoing laparoscopic surgery

ObjectiveThis research aimed to ascertain the effect of dexmedetomidine on pulmonary function in obese patients undergoing laparoscopic surgery.MethodsObese patients undergoing laparoscopic surgery under general anesthesia were separated into the control group (group C) and the dexmedetomidine group (group D) (n = 30). Patients in group D were infused with dexmedetomidine (1 μg/kg) intravenously for 10 min and then at a rate of 0.5 mg/kg h until 30 min before the end of the surgery, and those in group C were infused with an equal volume of saline. The surgery time points were divided into: before anesthesia induction (T0), 5 min after intubation (T1), 30 min after pneumoperitoneum (T2), 10 min after pneumoperitoneum release (T3), at the time of extubation (T4), 3 min after extubation (T5), and 24 h after surgery (T6). Arterial blood was collected for blood gas analysis to record arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2). Dynamic lung compliance (Cdyn), oxygenation index (OI), alveolar-arterial oxygen partial pressure difference (A-aDO2), and respiratory index (RI) were calculated. The time of surgery, anesthesia, CO2 pneumoperitoneum, eye-opening, and time from the end of surgery to extubation were recorded. Plasma IL-8 and IL-10 levels were measured from T0 to T6.ResultsThe time of surgery, anesthesia, CO2 pneumoperitoneum, eye-opening, and time from the end of surgery to extubation in group D were not statistically significant when compared with those in group C. Versus at the T1 time point, A-aDO2 and RI were higher and Cdyn and OI were lower in both groups at T2 and T3 time points. Versus group C, group D had higher Cdyn and OI and lower A-aDO2 and RI at T2 and T3 time points. Versus at the T0 time point, at each time point from T1 to T6, IL-8 and IL-10 levels were higher in both groups. Versus group C, group D had lower IL-8 and higher IL-10 levels at each time point from T1 to T6.ConclusionIn obese patients undergoing laparoscopic surgery under general anesthesia, the use of dexmedetomidine can improve the lung compliance and OI of the patients, inhibit the inflammatory response of the lungs of the patients and thus have a certain protective effect on the lung function.

End-tidal oxygen partial pressure is a strong prognostic predictive factor in patients with cardiac disease.

Cardiopulmonary exercise testing (CPET) variables represent central and peripheral factors and combined factors in the pathology of patients with cardiac disease. The difference in end-tidal oxygen partial pressure from resting to anaerobic threshold (ΔPETO2 ) may represent predominantly peripheral factors. This study aimed to verify the prognostic significance of ΔPETO2 for major adverse cardiac and cerebrovascular events (MACCE) in cardiac patients, including comparison with the minute ventilation-carbon dioxide production relationship (VE/VCO2 slope), and peak oxygen uptake (VO2 ). In total, 185 patients with cardiac disease who underwent CPET were consecutively enroled in this retrospective study. The primary endpoint was 3-year MACCE. The ability of ΔPETO2 , VE/VCO2 slope, and peak VO2 to predict MACCE was examined. Optimal cut-off values for predicting MACCE were 2.0 mmHg for ΔPETO2 (area under the curve [AUC]: 0.829), 29.8 for VE/VCO2 slope (AUC: 0.734), and 19.0 mL/min/kg for peak VO2 (AUC: 0.755). The AUC of ΔPETO2 was higher than those of VE/VCO2 slope and peak VO2 . The MACCE-free survival rate was significantly lower in the ΔPETO2 ≤ 2.0 group versus the ΔPETO2 > 2.0 group (44.4% vs. 91.2%, p < 0.001). ΔPETO2 ≤ 2.0 was an independent predictor of MACCE after adjustment for age and VE/VCO2 slope (hazard ratio [HR], 7.28; p < 0.001) and after adjustment for age and peak VO2 (HR, 6.52; p < 0.001). ΔPETO2 was a strong predictor of MACCE independent of and superior to VE/VCO2 slope and peak VO2 in patients with cardiac disease.

The Anti-Hypoxia Protective Effect of WYY026B by Interacting with Hemoglobin in Red Blood Cells

Background Exposure to hypoxia may experience damage to the heart, brain, lungs and other organs due to the low inspired O2. The improvement of endurance of human in resisting hypoxia and reducing hypoxia‑induced organ damage is an urgent problem to be solved. WYY026B is a honokiol derivatives by structural modification, and exhibits very potent pharma‑ cological activities and medicinal properties in brain ischemia/reperfusion (I/R) injury. Methods We used hypoxia model cerebral I/R model to identify the anti-hypoxia effect of WYY026B. High performance liquid chromatograph and immunofluorescence assay were used to detect the relationship between WYY026B and Red blood cells (RBCs). Interaction between WYY026B and hemoglobin (Hb) were validated by surface plasmon resonance assay (SPR). Results We demonstrated that WYY026B increased arterial oxygen saturation (SaO2) and arterial partial pressure of oxygen un‑ der hypoxia stress to improve the hypoxia tolerance. Blood gas analysis showed that WYY026B significantly decreased cervical venous SaO2 and increased arteriovenous oxygen partial pressure difference in I/R model. Nissl´s staining in‑ dicated that WYY026B significantly reduced the degree of hypoxia in brain tissue. A series of tests in vitro revealed that WYY026B could combine with RBCs. SPR assays showed that WYY026B interacted with Hb. Conclusion Overall, WYY026B maybe a new drug to enhance the ability of Hb to carry oxygen and to protect brain from the hypoxia injury

Parecoxib sodium alleviates ischemia reperfusion-induced pulmonary injury via inhibiting ERK/NF-κB and further activating the HIF-1α pathway.

IntroductionThe lungs are extremely vulnerable to ischemia/reperfusion (I/R), which is characterized by intense inflammation, oxidative stress, alveolar damage, and vascular permeability. Parecoxib sodium (Pare) has been shown to exert protective effects against multiple I/R‐induced tissue injuries. However, its role in I/R‐induced lung injury remains unknown. This study aimed to reveal the roles and mechanisms of Pare in pulmonary I/R injury.MethodsSixty‐six rats were randomly divided into three groups: The sham‐operated group, the pulmonary I/R group, and the Pare‐pretreated I/R group. Pare at 10 mg/kg or saline (vehicle control) were intraperitoneally administered to rats once per day for 5 consecutive days before ischemia. Serum and tissue samples were harvested following 2 h of reperfusion. The oxygenation index (OI) and alveolar‐arterial oxygen partial pressure difference (PA‐aO2) were analyzed. The levels or activities of malondialdehyde, superoxidase dismutase, catalase, glutathione peroxidase, intracellular reactive oxygen species, tumor necrosis factor‐α, interleukin (IL)‐6, and IL‐8 were examined. The mitochondrial membrane potential was measured. The protein expression levels of the extracellular signal‐regulated kinase (ERK), nuclear factor‐κB (NF‐κB) and their phosphorylated forms, and hypoxia‐inducible factor‐1α (HIF‐1α) were detected. Histological changes were observed using hematoxylin and eosin staining. Moreover, the survival rate following pulmonary I/R injury was recorded daily.ResultsPare significantly increased the OI, decreased the PA‐aO2, increased the levels of antioxidants, while decreasing the levels of oxidants, and alleviated mitochondrial dysfunction and the histopathological damage induced by I/R. Furthermore, Pare inhibited the expression of proinflammatory cytokines, suppressed the activation of ERK and NF‐κB, further increased HIF‐1α expression, and significantly improved the rat survival rate.ConclusionsPare pretreatment attenuated lung I/R injury by inhibiting oxidative stress and the inflammatory response possibly via inhibiting the activation of the ERK/NF‐κB pathway and further activating the HIF‐1α pathway.

A core‐shell structured diffusion‐bubbling membrane for efficient oxygen separation: Formation and transport properties

AbstractThe newly developed core‐shell structured molten oxide membranes with fast combined diffusion‐bubbling oxygen mass transfer and theoretically infinite selectivity are of technological interest because of their high separation efficiency. In this article, a core‐shell structured molten V2O5–Cu2O‐ based diffusion‐bubbling membrane was prepared by one‐step thermal treatment of initial CuO–25 wt.% Cu5V2O10 ceramic composite in a chemical field (under an oxygen partial pressure difference across the composite) above copper vanadate peritectic transformation temperature (816°C). Oxygen fluxes through the membrane were measured at 830°C, using either gas mixtures (O2 + N2) with different oxygen concentrations or air as feed gas at the shell of the membrane and helium (He) as sweep gas. Oxygen flux through the membrane with a shell thickness of 0.15–0.61 mm was 3.8·10–8–1.4·10–7 mol/cm2/s under an oxygen partial pressure difference of 0.1 –0.75 atm, respectively. The effect of oxygen partial pressure on the thickness of the membrane shell is found. The relationship between membrane shell thickness, oxygen partial pressure difference across the membrane, and oxygen permeation flux through the membrane is established. Oxygen permeation flux through the dual‐phase MIEC membrane shell is described in terms of the diffusion model. Oxygen permeation flux through the membrane core is described both within the framework of the stationary model and nonstationary model for uniform (the membrane thickness is much larger than the characteristic distance of bubble dynamic relaxation) and accelerated (the membrane thickness is comparable to the characteristic distance of bubble dynamic relaxation) bubble motion in a viscous oxide melt, respectively.

Partial Pressure of Oxygen in Stunted and Normal Growth Children and Risk Factors for Stunting by Altitude

Background Risk factors for stunting are not only during a child’s growth period, but also during maternal period. Pregnant mothers at high altitude could influence stunted growth to the child due to low oxygen partial pressure. Aim Observing and comparing risk factors for stunting by altitude and other contributing factors. Methods This was a cross-sectional study conducted to patients <5 years old in Ulu Pungkut highland (700 meters above sea level) and Desa Singkuang lowland (4 – 6 meters above sea level) from March 2019. Anthropometric and oxygen partial pressure measurements were done to 38 children in the highland and 38 children in the lowland with stunted and normal growth. Results PaCO2, total CO2 and HCO3 values were significantly different among the research subjects residing in the lowland and highland (p<0.0001). There were no significant differences in oxygen partial pressure between children with stunted and normal growth. Conclusion Subjects in highland and lowland had significant differences in PaCO2, total CO2 and HCO3 between different altitudes in this study. However, oxygen partial pressure was not significantly different between stunted and normal growth children.

This Month in Anesthesiology

This Month in Anesthesiology

Sequential non-invasive following short-term invasive mechanical ventilation in the treatment of tuberculosis with respiratory failure: a randomized controlled study

BackgroundInvasive and non-invasive mechanical ventilation (MV) have been combined as sequential MV in the treatment of respiratory failure. However, the effectiveness remains unclear. Here, we performed a randomized controlled study to assess the efficacy and safety of sequential MV in the treatment of tuberculosis with respiratory failure.MethodsForty-four tuberculosis patients diagnosed with respiratory failure were randomly divided into sequential MV group (n = 24) and conventional MV group (n = 20). Initially, the patients in both groups received invasive positive pressure ventilation. When the patients' conditions were relieved, the ventilation modality in sequential MV group was switched to oronasal face mask continuous positive airway pressure until weaning.ResultsAfter treatment, the patients in sequential MV group had similar respiratory rate, heart rate, oxygenation index, alveolo-arterial oxygen partial pressure difference (A-aDO2), blood pH, PaCO2 to those in conventional MV group (all P value > 0.05). There was no significant difference in ventilation time and ICU stay between the two groups (P > 0.05), but sequential MV group significantly reduced the time of invasive ventilation (mean difference (MD): − 36.2 h, 95% confidence interval (CI) − 53.6, − 18.8 h, P < 0.001). Sequential MV group also reduced the incidence of ventilator-associated pneumonia (VAP; relative risk (RR): 0.44, 95% CI 0.24, 0.83, P = 0.006) and atelectasis (RR:0.49, 95% CI 0.24,1.00, P = 0.040).ConclusionsSequential MV was effective in treating tuberculosis with respiratory failure. It showed advantages in reducing invasive ventilation time and ventilator-associated adverse events.Registration number for clinical trialChinese Clinical Trial Registry ChiCTR2000032311, April 21st, 2020

Microstructure Control of Ceramic Functional Membrane by Electrophoretic Deposition Method and Its Application to Oxygen Separation Membrane using Mixed Ionic-Electronic Conductor

Pure oxygen is mainly produced by separating oxygen from the air. Oxygen separation membranes using mixed oxide ionic-electronic conductor (MIEC) selectively separate high-purity oxygen via oxide ions using the oxygen partial pressure difference on both sides of the membrane as a driving force. It is expected to be industrially put into practical use as a device suitable for on-site oxygen production. In order to improve the oxygen separation efficiency, it is important to increase the surface reaction area and reduce the thickness of the membrane. A multi-layered structure composed of “porous layer / dense thin layer / porous support layer” is suitable for the purpose. Electrophoretic deposition (EPD) is a very suitable method for forming such a multilayered structure. This review introduces the processing viewpoints to optimize various conditions such as suspension preparation conditions, EPD conditions, and co-sintering conditions. Finally, the oxygen separation performance is tested for the obtained membrane and the importance of microstructural design and process selection in improving oxygen separation performance is discussed.

Metabolic heterogeneity and immunocompetence of infiltrating immune cells in the breast cancer microenvironment (Review).

Breast cancer is one of the most common malignancies in women and is characterized by active immunogenicity. Immune cell infiltration plays an important role in the development of breast cancer. The degree of infiltration influences both the response to and effect of treatment. However, immune infiltration is a complex process. Differences in oxygen partial pressure, blood perfusion and nutrients in the tumor microenvironment (TME) suggest that infiltrating immune cells in different sites experience different microenvironments with corresponding changes in the metabolic mode, that is, immune cell metabolism is heterogenous in the TME. Furthermore, the present review found that lipid metabolism can support the immunosuppressive microenvironment in breast cancer based on a review of published literature. Research in this field is still ongoing; however, it is vital to understand the metabolic patterns and effects of different microenvironments for antitumor therapy. Therefore, this review discusses the metabolic responses of various immune cells to different microenvironments in breast cancer and provides potentially meaningful insights for tumor immunotherapy.

Parecoxib mitigates lung ischemia-reperfusion injury in rats by reducing oxidative stress and inflammation and up-regulating HO-1 expression.

ABSTRACTPurpose:To investigate the protective effect of parecoxib against lung ischemia-reperfusion injury (LIRI) in rats and the mechanism.Methods:Thirty rats were divided into sham-operated, LIRI and LIRI+parecoxib groups. LIRI model (ischemia for 60 min, followed by reperfusion for 120 min) was constructed in LIRI and LIRI+parecoxib groups. In LIRI+parecoxib group, 10 mg/kg parecoxib was given via femoral vein 15 min before ischemia beginning. At the end of the reperfusion, blood gas analysis, lung wet to dry mass ratio measurement, lung tissue biochemical determination and heme oxygenase-1 (HO-1) protein expression determination were performed.Results:Compared with LIRI group, in LIRI+parecoxib group the oxygenation index was significantly increased, the alveolar-arterial oxygen partial pressure difference was significantly decreased, the lung wet to dry mass ratio was significantly decreased, the lung tissue malondialdehyde content was significantly decreased, the lung tissue superoxide dismutase and myeloperoxidase activities were significantly increased, the lung tissue tumor necrosis factor α and interleukin 1β levels were significantly decreased, and the lung tissue HO-1 protein expression level was significantly increased (all P < 0.05).Conclusions:Parecoxib pretreatment can mitigate the LIRI in rats by reducing oxidative stress, inhibiting inflammatory response and up-regulating HO-1 expression in lung tissue.

Effect of Goal-Directed Fluid Therapy on Lung Function, Cognitive Function and Inflammatory Response in Patients Undergoing Radical Esophageal Cancer Surgery under One-Lung Ventilation

Objective: To explore the effects of goal-directed fluid therapy (GDFT) on lung function, cognitive function and inflammatory response in patients undergoing radical esophageal cancer surgery under one-lung ventilation. Methods: Sixty-seven patients undergoing radical esophageal cancer surgery were divided into GDFT group (GDFT therapy) and control group (conventional liquid therapy). The changes in patients’ pulmonary function, cognitive function and inflammatory response were evaluated. Results: Both alveolar-arterial oxygen partial pressure difference [P(A-a)O2] and respiratory index (RI) increased at one-lung ventilation for 30 minutes (T2) and decreased at one-lung ventilation for 60 minutes (T3), and after surgery (T4) in the two groups, and the GDFT group was lower than the control group (P 0.05); theoxygenation index (OI) of the two groups decreased at T2, T3, and T4 compared with that at T1 (before one-lung ventilation), and the GDFT group was higher than the control group (P 0.05). At T4 and T5, the tumor necrosis factor α (TNF-α), interleukin 6 (IL-6), central nervous system specific protein (S100β), and neuron specific enolase (NSE) in the GDFT group were lower compared to the control group (P 0.05), while interleukin-10 (IL-10) was higher compared to the control group (P 0.05); the incidence of perioperative neurocognitive disorder (PND) in the GDFT group was lower than that in the control group (P 0.05). Conclusion: GDFT can help prevent lung injury during radical esophageal cancer surgery under one-lung ventilation, reduce the body’s inflammatory response, and reduce the incidence of perioperative cognitive disorder to a certain extent.

Effect of Dexmedetomidine on Postoperative Lung Injury during One-Lung Ventilation in Thoracoscopic Surgery.

Objective To investigate the effect of dexmedetomidine on postoperative lung injury in patients undergoing thoracoscopic surgery. Methods From March 2019 to October 2019, 40 patients were randomly divided into two groups: dexmedetomidine group (group D) and control group (group C). Except recording the general condition of the patients in both groups preoperatively and intraoperatively, the oxygenation index (OI) and alveolar-arterial oxygen partial pressure difference (A-aDO2) were monitored at admission (T0), immediately after one-lung ventilation (T1), 0.5 h after one-lung ventilation (T2), and 15 minutes after inhaling air before leaving the room (T3). The content of IL-8 in arterial blood was measured by enzyme-linked immunosorbent assay (ELISA) at T0 and T2, and the expression of AQP1 protein in isolated lung tissue was measured by immunohistochemistry and Western blot. The incidence of postoperative pulmonary complications (atelectasis, pneumonia, and acute respiratory distress syndrome) was used as the index of lung injury. Results There was no significant difference in the general condition before and during operation between the two groups. There was no significant difference in arterial blood IL-8 content between the two groups at the T0 time point, but the arterial blood IL-8 content at the T2 time point was significantly higher than that at the T0 time point, especially in group C. The results of immunohistochemistry and Western blot showed that the expression level of AQP1 protein in the isolated lung tissue of group D was significantly higher than that of group C (P < 0 05). At T3, the OI of group D was significantly higher than that of group C, and the A-aDO2 of group D was significantly lower than that of group C (P < 0.05). There was no significant difference in the incidence of postoperative PPCs between the two groups. Conclusion Dexmedetomidine can reduce the level of plasma IL-8 and upregulate the expression of AQP1 in the lung tissue of patients undergoing thoracoscopic surgery under one-lung ventilation, but it has no significant effect on the incidence of postoperative PPCs. Dexmedetomidine can be safely used in thoracoscopic surgery and has a certain protective effect on lung injury.

Effect of Intravenous Injection of Vitamin C on Postoperative Pulmonary Complications in Patients Undergoing Cardiac Surgery: A Double-Blind, Randomized Trial.

PurposeIn this study, the effect of intravenous vitamin C during surgery on the incidence of postoperative pulmonary complications (PPCs) in patients undergoing cardiopulmonary bypass and cardiac surgery was observed, and its protective effect on the lungs was evaluated to provide a reference for clinical medication.Patients and MethodsPatients undergoing cardiac surgery under cardiopulmonary bypass (CPB) were selected. The patients were divided into group A and group C by random sequence. Patients in group A received intravenous vitamin C 1 g 10 minutes after induction of anesthesia, 10 minutes before cardiac reanimation and at the moment of sternal closure. Patients in group C were intravenously injected with the same volume of saline at the same time. The primary outcome was the postoperative pulmonary complication severity score. Other outcomes were the incidence of PPCs, awakening time, extubation time, length of ICU stay, length of hospital stay, adverse events, oxygenation index (PaO2/FiO2), alveolar arterial oxygen partial pressure difference (A-aDO2), dynamic lung compliance (Cd) and static lung compliance (Cs).ResultsSeventy patients completed the study. Compared to group C, the postoperative pulmonary complication score [2(2–3) vs 2(1–2); P=0.009] and the incidence of postoperative pulmonary complications (32.43% vs 12.12%; P =0.043) were lower in group A. There were no significant differences in awakening time, extubation time, length of ICU stay, length of hospital stay, adverse events, PaO2/FiO2, A-aDO2, Cs, and Cd between the two groups (P>0.05).ConclusionIn summary, this small randomized trial including low-risk cardiac surgery patients shows that intravenous vitamin C may safely be administered and may be helpful to prevent PPCs after cardiac surgery.

Exploration and correlation analysis of changes in Krebs von den Lungen-6 levels in COVID-19 patients with different types in China.

This study aimed to determine the clinical significance of Krebs von den Lungen-6 (KL-6) in patients with COVID-19, so as to find a marker with high sensitivity, specificity and easy detection to evaluate the lung injury and inflammation of COVID-19. Sixty-three COVID-19 patients and 43 non-COVID-19 patients with similar clinical phenotypes and/or imaging findings were enrolled to test the levels of KL-6 using chemiluminescent immunoassay. In addition, the blood gas, imaging and lymphocyte factors tests were collected from all participants. The data was finally analyzed using multivariate statistical analysis. The results showed KL-6 levels in COVID-19 patients were higher than those in non-COVID-19 patients (P < 0.001). Moreover, the KL-6 levels in severe and critically severe patients were significantly upregulated compared with patients with mild and common type (P < 0.05). Meanwhile, the imaging evaluation showed a significant correlation between KL-6 and pulmonary lesion area (P < 0.05). KL-6 was also found to be significantly correlated with oxygenation index and oxygen partial pressure difference of alveolar artery (PA-aDO2) (Both P < 0.01). In conclusion, KL-6 could be an indicator to evaluate the progression of COVID-19, which is parallel to the level of lung injury and inflammation in patients. Moreover, it can also reflect the pulmonary ventilation function.

CO2‐resistant SDC‐SSAF oxygen selective dual‐phase hollow fiber membranes

AbstractCe0.85Sm0.15O1.925–Sm0.6Sr0.4Al0.3Fe0.7O3‐δ (SDC‐SSAF) hollow fiber membranes aimed for oxyfuel application are fabricated via a phase inversion‐sintering technique using powders synthesized from EDTA–citrate complex method. Oxygen ions transport is revealed to be the limiting step that determines the overall oxygen transport rate in SDC‐SSAF. SDC‐SSAF hollow fiber membrane attained a maximum flux of 2.6 ml min−1 cm−2 at 950°C under an oxygen partial pressure difference of 1/0.02 atm (feed/permeate). Variation in oxygen partial pressure on the permeate side exerts larger influence on the oxygen permeation flux relative to the change on the feed side. Stability tests over 100 h demonstrate stable oxygen permeation flux under both He and CO2 sweep conditions.

SARS-CoV-2 infection of the liver directly contributes to hepatic impairment in patients with COVID-19

Background & AimsLiver enzyme abnormalities are common in patients with coronavirus disease 2019 (COVID-19). Whether or not severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can lead to liver damage per se remains unknown. Herein, we reported the clinical characteristics and liver pathological manifestations of COVID-19 patients with liver enzyme abnormalities.MethodsWe analyzed 156 patients diagnosed with COVID-19 from 2 designated centers in China and compared clinical features between patients with or without elevated aminotransferases. Postmortem liver biopsies were obtained from 2 cases who had elevated aminotransferases. We investigated the patterns of liver impairment by electron microscopy, immunohistochemistry, TUNEL assay and pathological studies.ResultsSixty-four out of 156 (41.0%) patients with COVID-19 had elevated aminotransferases. The median levels of alanine aminotransferase were 50 U/L vs. 19 U/L, respectively, aspartate aminotransferase were 45.5 U/L vs. 24 U/L, respectively in abnormal and normal aminotransferase groups. Liver enzyme abnormalities were associated with disease severity, as well as a series of laboratory tests including higher alveolar-arterial oxygen partial pressure difference, higher gamma-glutamyltransferase, lower albumin, decreased CD4+ T cells and B lymphocytes. Ultrastructural examination identified typical coronavirus particles, characterized by spike structures, in the cytoplasm of hepatocytes in 2 COVID-19 cases. SARS-CoV-2-infected hepatocytes displayed conspicuous mitochondrial swelling, endoplasmic reticulum dilatation and glycogen granule decrease. Histologically, massive hepatic apoptosis and some binuclear hepatocytes were observed. Taken together, both ultrastructural and histological evidence indicated a typical lesion of viral infection. Immunohistochemical results showed scarce CD4+ and CD8+ lymphocytes. No obvious eosinophil infiltration, cholestasis, fibrin deposition, granuloma, massive central necrosis, or interface hepatitis were observed.ConclusionsSARS-CoV-2 infection in the liver directly contributes to hepatic impairment in patients with COVID-19. Hence, a surveillance of viral clearance in liver and long-term outcome of COVID-19 is required.Lay summaryLiver enzyme abnormalities are common in patients with coronavirus disease 2019 (COVID-19). We reported the clinical characteristics and liver pathological manifestations of COVID-19 patients with elevated liver enzymes. Our findings suggested that SARS-CoV-2 infection of the liver is a crucial factor contributing to hepatic impairment in patients with COVID-19.

Effects of low tidal volume protective lung ventilation versus pressure controlled ventilation on oxygenation in patients un-dergoing gynecologic laparoscopic surgery

Objective To evaluate the effectiveness and safety of low tidal volume protective lung ventilation (PLV) and pressure controlled ventilation (PCV) in patients undergoing gynecologic laparoscopic surgery. Methods A total of 144 patients who were scheduled for gynecologic laparoscopic surgery in our hospital were enrolled. According to the random number table method, they were divided into two groups (n=72): a PLV group and a PCV group. The PLV group used a tidal volume of 6 ml/kg, an inspiration and expiration ratio of 1∶2, a respiratory rate of 16 breaths per minute, and a positive end expiratory pressure of 5 cmH2O (1 cmH2O=0.098 kPa). In the PCV group, the ventilation pressure was maintained at a tidal volume of 8 ml/kg, with an inspiration and expiration ratio of 1∶2, and a respiratory rate of 12-16 breaths per minute. Their airway peak pressure (Ppeak) and mean airway pressure (Pmean) were recorded 5 min after tracheal intubation (T1), 10 min after pneumoperitoneum (T2), 20 min af-ter pneumoperitoneum (T3), and 10 min after pneumonectomy (T4), while dynamic lung compliance (Cdyn) was calculated. Blood gas analysis was performed at T3 and T4 to record arterial oxygen partial pressure (PaO2), arterial CO2 partial pressure (PaCO2), and alveolar-arterial oxygen partial pressure difference (A-aDO2), while oxygenation index (OI) was calculated. Results At T3, the PLV group presented remarkably increased Ppeak and Pmean and decreased Cdyn, compared with the PCV group (P 0.05). There was no significant differ-ence in the incidence of respiratory complications and the length of hospitalization stay between the two groups (P>0.05). Conclusions For patients undergoing gynecologic laparoscopic surgery, PCV is helpful to maintain stable respiratory dynamics, while low tidal volume PLV is helpful to maintain oxygenation function during surgery. There is no significant difference in safety be-tween the two types of treatment. Key words: Gynaecology; Laparoscopy; Protective lung ventilation mode; Pressure controlled ventilation; Oxygenation function

Effects of inverse ratio ventilation combined with lung protective ventilation on pulmonary function in patients with severe burns for surgery

ABSTRACT Objective To investigate the effects of inverse ratio ventilation combined with lung-protective ventilation on pulmonary function and inflammatory factors in severe burn patients undergoing surgery. Populations and Methods: Eighty patients with severe burns undergoing elective surgery were divided randomly into two groups: control (CG, n = 40) and experiment (EG, n = 40). The CG had conventional ventilation, whereas the EG were ventilated with tidal volume (TV) of 6–8 ml/kg, I (inspiration): E (expiration) of 2:1, and positive end-expiratory pressure (PEEP) 5 cm H2O. The following variables were evaluated before (T0), 1 h after start of surgery (T1) and after surgery (T2): oxygenation index (OI), partial pressure of carbon dioxide (PaCO2), TV, peak airway pressure (Ppeak), mean airway pressure (Pmean), PEEP, pulmonary dynamic compliance (Cdyn), alveolar–arterial difference of oxygen partial pressure D(A-a)O2, lactic acid (Lac), interleukin (IL)-6 and IL-10, and lung complications. Results: At T1 and T2 time points, the OI, Pmean and Cdyn were significantly greater in the EG than in the CG while the TV, Ppeak, D(A-a)O2, IL-6 and IL-10 were significantly smaller in the EG than in the CG. At the end of the surgery, the Lac was significantly smaller in the EG than in the CG (1.28 ± 0.19 vs. 1.40 ± 0.23 mmol/L). Twenty-four hours after the surgery, significantly more patients had hypoxemia (27.5 vs. 10.0%), increased expectoration (45.0 vs. 22.5%), increased lung texture or exudation (37.5 vs. 17.5%) in the CG than in the EG. Conclusions: Inverse ratio ventilation combined with lung-protective ventilation can reduce Ppeak, increase Pmean and Cdyn, improve the pulmonary oxygenation function, and decrease ILs in severe burn surgery patients.

Clinical characteristics of acute pulmonary embolism at different altitudes in plateau areas

Objective: To analyze the clinical characteristics of pulmonary embolism patients from different altitudes in plateau areas. Methods: A retrospective cross-sectional study was used to analyze the patients with acute pulmonary embolism diagnosed definitely by pulmonary angiography or pulmonary artery CT angiography admitted to Tibet Autonomous Region People's Hospital from August 2014 to December 2018. The subjects were divided into 3 groups according to the altitude of long-term residence before onset, i.e. low-altitude group (group 1, 2 700 m ≤ altitude ≤3 700 m, n=44), medium-altitude group (group 2, 3 700 m<altitude ≤4 000 m, n=30) and high altitude group (group 3, 4 000 m<altitude ≤4 800 m, n=32). The clinical data, auxiliary examination and risk stratification of pulmonary embolism patients at different altitudes were compared and analyzed. Results: The incidence of chest pain, dyspnea and lower limb fracture in the three groups were statistically significant (P<0.05). The incidence of chest pain in group 2 (70%) was higher than that in group 1(40.9%), and dyspnea in group 3 (93.8%) was higher than that in group 2(66.7%), while lower limb fracture in group 3 (43.8%) was higher than that in group 1(15.9%). The differences in arterial oxygen partial pressure, hemoglobin and D-dimer among the three groups were statistically significant (P<0.05). The arterial oxygen partial pressure [52(43.5-63.5)mmHg] in group 3 was lower than that in group 1 [60 (53.25-73) mmHg]. The hemoglobin (163.1±43.3 g/L) and D-dimer [5.6(3.7-12.6)mg/L] in group 3 were higher than those in group 1 [143.5±38.9 g/L and 3.8(2.0-7.5)mg/L respectively]. The risk stratification of the three groups of patients was moderate or low, and there was no statistical difference among the three groups. In patients with the same low-risk grade, the D-dimer in group 3 was higher than that in group 1 [5.8(4.2-14.8)mg/L and 3.6(2.3-5.8)mg/L respectively, P<0.05]. In patients with the same moderate risk level, the arterial oxygen partial pressure in group 3 was lower than that in group 1 [47.0(36.0-58.0)mmHg and 59.5(52.3-68.5)mmHg, respectively, P<0.05]. Conclusion: There was no difference in the risk stratification of pulmonary embolism from different altitudes in plateau areas, but patients who lived at higher altitudes for a long time showed more significant hypoxemia and increased hemoglobin and D-dimer levels.