ObjectiveTo evaluate the effect of positive end-expiratory pressure (PEEP) on respiratory function and hemodynamics in acute lung injury (ALI) with intra-abdominal hypertension (IAH). MethodsSix pigs were anesthetized and received mechanical ventilation (MV). Volume controlled ventilation was set with tidal volumn(VT) of 8 mL/kg,respiratory rate(RR) of 16 bpm,inspired oxygen concentration (FiO2) of 0.40,and PEEP of 5 cm H2O. ALI was induced by repeated lung lavage with diluted hydrochloric acid (pH<2.5) until PaO2/FiO2 declined to 150 mm Hg or less to established ALI model. Intra-abdominal hypertension was induced by an nitrogen inflator to reach intra-abdominal pressure of 20 mm Hg. Respiratory parameters and hemodynamics were continuously recorded at different PEEP levels(5,10,15,and 20 cm H2O). Every level was maintained for one hour. ResultsPaO2/FiO2 in PEEP5,10,15 and 20 were 90±11,102±10,172±23 and 200±34 mm Hg respectively. PaO2/FiO2 in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). Chest wall compliance (Ccw) in PEEP5,15 and 20 were 26±3,76±15 and 85±14 mL/cm H2O respectively. Ccw in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in lung compliance (CL) in different PEEP levels (P>0.05). Plateau pressure(Pplat) in PEEP5,10,15 and 20 were 30±3,31±2,36±2 and 38±4 cm H2O respectively. Pplat in PEEP15 and 20 were significantly higher than those in PEEP5 and 10 (P<0.05). There was no significant difference in Pplat between PEEP15 and 20 (P>0.05). Heart rate (HR) in PEEP5,15 and 20 were 113±17,147±30,and 160±30 beat/min respectively. HR in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in HR between PEEP15 and 20 (P>0.05).Cardiac index (CI) in PEEP5 and 20 were 4.5±0.6 and 3.5±0.6 L·min-1·m-2 respectively. CI in PEEP20 was significantly lower than that in PEEP5 (P<0.05). There was no significant difference in CI in PEEP5,10 or 15(P>0.05). Central venous pressure(CVP) in PEEP5,15 and 20 were 12±2,17±2,and 18±3 mm Hg respectively. CVP in PEEP15 and 20 were significantly higher than those in PEEP5 (P<0.05). There was no significant difference in CVP between PEEP15 and 20 (P>0.05). There were no significant differences in MAP,SVRI,ITBVI,GEDI,PVPI,or EVLWI between different PEEP levels. ConclusionConcomitant ALI and IAH can induce great impairments in respiratory physiology. When PEEP is gradually increased,oxygenation and the respiratory function are improved without significant secondary hemodynamic disturbances.
ObjectiveTo perform a meta-analysis on the positive rate of hepatitis C virus (HCV) antibody among pregnant females in China from 2008 to 2018, so as to provide scientific references for the prevention and treatment of HCV infection among pregnant females.MethodsDatabases including PubMed, Web of Science, SinoMed, CNKI, VIP, and WanFang Data were electronically searched to collect observational studies on the positive rate of HCV antibody among pregnant females in China from January, 2008 to December, 2018. Two reviewers independently screened literature, extracted data and evaluated risk of bias of included studies. Meta-analysis was then performed using Stata 15.0 software.ResultsA total of 108 studies involving 657 765 individuals were included. Results of meta-analysis showed that the overall positive rate of HCV antibody among pregnant females in Chinese was 0.235% (95%CI 0.189% to 0.286%). Subgroup analysis showed that the positive rate of HCV antibody among pregnant females in western China to be the highest 0.291% (95%CI 0.221% to 0.378%), the northeast China to be 0.240% (95%CI 0.099% to 0.442%), the central China to be 0.235% (95%CI 0.016% to 0.319%), and the east China to be the lowest 0.193 % (95%CI 0.119% to 0.281%). The HCV antibody positive rate of pregnant females from hospital was 0.291% (95%CI 0.221% to 0.372%) and was higher than that from AIDS surveillance site which was 0.164% (95%CI 0.122% to 0.207%).ConclusionsThe prevalence of HCV antibody among pregnant females maintains at a low level in China.
ObjectiveTo evaluate the effect of driving pressure-guided lung protective ventilation strategy on lung function in adult patients under elective cardiac surgery with cardiopulmonary bypass.MethodsIn this randomized controlled trial, 106 patients scheduled for elective valve surgery via median sternal incision under cardiopulmonary bypass from July to October 2020 at West China Hospital of Sichuan University were included in final analysis. Patients were divided into two groups randomly. Both groups received volume-controlled ventilation. A protective ventilation group (a control group, n=53) underwent traditional lung protective ventilation strategy with positive end-expiratory pressure (PEEP) of 5 cm H2O and received conventional protective ventilation with tidal volume of 7 mL/kg of predicted body weight and PEEP of 5 cm H2O, and recruitment maneuver. An individualized PEEP group (a driving pressure group, n=53) received the same tidal volume and recruitment, but with individualized PEEP which produced the lowest driving pressure. The primary outcome was oxygen index (OI) after ICU admission in 30 minutes, and the secondary outcomes were the incidence of OI below 300 mm Hg, the severity of OI descending scale (the Berlin definition), the incidence of pulmonary complications at 7 days after surgery and surgeons’ satisfaction on ventilation.ResultsThere was a statistical difference in OI after ICU admission in 30 minutes between the two groups (273.5±75.5 mm Hg vs. 358.0±65.3 mm Hg, P=0.00). The driving pressure group had lower incidence of postoperative OI<300 mm Hg (16.9% vs. 49.0%, OR=0.21, 95%CI 0.08-0.52, P=0.00) and less severity of OI classification than the control group (P=0.00). The incidence of pulmonary complications at 7 days after surgery was comparable between the driving pressure group and the control group (28.3% vs. 33.9%, OR=0.76, 95%CI 0.33-1.75, P=0.48). The atelectasis rate was lower in the driving pressure group (1.0% vs. 15.0%, OR=0.10, 95%CI 0.01-0.89, P=0.01).ConclusionApplication of driving pressure-guided ventilation is associated with a higher OI and less lung injury after ICU admission compared with the conventional protective ventilation in patients having valve surgery.
Without artificial airway though oral, nasal or airway incision, the bi-level positive airway pressure (Bi-PAP) has been widely employed for respiratory patients. In an effort to investigate the therapeutic effects and measures for the respiratory patients under the noninvasive Bi-PAP ventilation, a therapy system model was designed for virtual ventilation experiments. In this system model, it includes a sub-model of noninvasive Bi-PAP respirator, a sub-model of respiratory patient, and a sub-model of the breath circuit and mask. And based on the Matlab Simulink, a simulation platform for the noninvasive Bi-PAP therapy system was developed to conduct the virtual experiments in simulated respiratory patient with no spontaneous breathing (NSB), chronic obstructive pulmonary disease (COPD) and acute respiratory distress syndrome (ARDS). The simulated outputs such as the respiratory flows, pressures, volumes, etc, were collected and compared to the outputs which were obtained in the physical experiments with the active servo lung. By statistically analyzed with SPSS, the results demonstrated that there was no significant difference (P > 0.1) and was in high similarity (R > 0.7) between the data collected in simulations and physical experiments. The therapy system model of noninvasive Bi-PAP is probably applied for simulating the practical clinical experiment, and maybe conveniently applied to study the technology of noninvasive Bi-PAP for clinicians.
Simulation of the human biological lung is a crucial method for medical professionals to learn and practice the use of new pulmonary interventional diagnostic and therapeutic devices. The study on ventilation effects of the simulation under positive pressure ventilation mode provide valuable guidance for clinical ventilation treatment. This study focused on establishing an electrical simulation ventilation model, which aims to address the complexities in parameter configuration and slow display of air pressure and airflow waveforms in simulating the human biological lung under positive pressure ventilation mode. A simulated ventilation experiment was conducted under pressure-regulated volume control (PRVC) positive pressure ventilation mode, and the resulting ventilation waveform was compared with that of normal adults. The experimental findings indicated that the average error of the main reference index moisture value was 9.8% under PRVC positive pressure ventilation mode, effectively simulating the ventilatory effect observed in normal adults. So the established electrical simulation ventilation model is feasible, and provides a foundation for further research on the simulation of human biological lung positive pressure ventilation experimental platform.
Objective To investigate the effects of mechanical ventilation( MV) via different tidal volume ( VT) in combination with positive end expiratory pressure( PEEP) on dogs with acute lung injury( ALI) . Methods Dog model of oleic acid-induced ALI was established. And after that animals were randomized into different MV groups ( included low VT group, VT =6 mL/kg; and high VT group, VT =20 mL/kg) and ventilated for 6 h with a PEEP of 10 cmH2O. Arterial blood gas wasmeasured before, during and after ALI model was established ( at 1 h,2 h, 4 h and 6 h during MV) . The albumin concentration in BALF and pathological change of the lung tissue were evaluated in order to determine the lung injury while animals were sacrificed after 6 h MV. Results ALI model was successfully established ( 2. 50 ±0. 80) hours after oleic acid injection. Arterial pH decreased much severer in the low VT group than the high VT group( P lt;0. 01) . PaO2 and SaO2 in ventilation groups decreased after modeling but increased after MV, and PaO2 and SaO2 were significantly higher in the low VT group than the high VT group after 6 h MV( P lt;0. 05) . PaCO2 fluctuated less in the high VT group, while it increased significantly in the low VT group after MV( P lt; 0. 01) . Oxygenation index( PaO2 /FiO2 ) was lowered after modeling( P lt; 0. 01) , decreased to about 190 mm Hg after 1 h MV. And PaO2 /FiO2 in low VT group was significantly higher than the high VT group after 6 h MV( P lt; 0. 05) . BALF albumin concentration and the lung injury score in the low VT group were both significantly lower than the high VT group( both P lt; 0. 05) . Conclusions Ventilation with PEEP could improve the oxygenation of ALI dogs, and low VT ventilation improves the oxygenation better than high VT. Otherwise, low VT could induce hypercapnia and ameliorate lung injury caused by high VT MV.
Objective To study the influence of low-tidal volume and positive end expiratory pressure (PEEP) protective ventilation on cardiac output volume in elderly patients under general anesthesia. Methods From August 2012 to July 2014, 60 elderly patients undergoing selective surgery were divided into three groups with 20 patients in each. Group A was treated with conventional ventilation: tidal volume at 8 mL/kg, PEEP at 0 cm H2O (1 cm H2O=0.098 kPa); group B was treated with a tidal volume of 6 mL/kg and a PEEP of 5 cm H2O; group C was treated with a tidal volume of 6 mL/kg and a PEEP of 8 cm H2O. We then observed and analyzed the blood pressure, heart rate, cardiac output, arterial blood gas and airway mean pressure before induction of anesthesia (T0), 15 minutes of mechanical ventilation after the induction of anesthesia (T1), 60 minutes after anesthesia induction (T2), and 15 minutes after tracheal extubation (T3). Results In all the three groups, the mean arterial pressure and cardiac output were stable. In group B and C, central venous pressure increased significantly, the mean airway pressure and lung compliance increased, and the arterial oxygen branch pressure also increased significantly (P < 0.05). Conclusion Low-tidal volume combined with 5-cm H2O or 8-cm H2O positive end expiratory pressure lung-protective ventilation had a small influence on the cardiac output of elderly patients under anesthesia, which can be safely used.
Objective To investigate the effects of positive end-expiratory pressure (PEEP) level on end-expiratory lung volume (EELV) during assisted ventilation in chronic obstructive pulmonary disease （COPD） patients，to provide physiological evidence to guide optimal setting of PEEP level in clinical practice.Methods Eight intubated patients with acute exacerbation of COPD were recruited for the study when the patients were in relatively stable condition after treatment.The static intrinsic PEEP (PEEPistat) and dynamic intrinsic PEEP (PEEPidyn) were measured by using airway occlusion method and esophageal balloon-tipped catheter technique,respectively.Changes in EELV (ΔEELV) were measured with inspiratory capacity (IC) method.Relations between PEEP level and ΔEELV were analyzed by curve estimation method.Results ΔEELV as a function of level of PEEP was shown as a sigmoid model.The low inflection points of the curves when PEEP levels were expressed as PEEP/PEEPistat ratio，PEEP/PEEPidyn ratio or actual PEEP setting (PEEP-a) were 0.74，0.76 or 3.6 cm H2O,respectively.The corresponding ΔEELV expressed as ΔEELV/IC（%） were 9.6%，9.1% and 7.4%,respectively.Conclusions In AECOPD patients demanding mechanical ventilation，the changes of lung volume (ΔEELV) in response to progressive increase of PEEP level were shown to be a sigmoid model.Setting PEEP level at 0.74 of PEEPistat，or 0.76 of PEEPidyn can avoid the steep increase of lung volume.
ObjectiveTo evaluate the correlation between positive end-expiratory pressure (PEEP) level and postoperative pulmonary complications (PPCs) in patients undergoing thoracoscopic lung surgery. MethodsThe clinical data of patients who underwent elective thoracoscopic lung surgery at West China Hospital of Sichuan University from January 2022 to June 2023 were retrospectively analyzed. Patients were divided into 2 groups according to intraoperative PEEP levels: a PEEP 5 cm H2O group and a PEEP 10 cm H2O group. The incidence of PPCs in the two groups after matching was compared using a nearest neighbor matching method with a ratio of 1∶1, setting the clamp value as 0.02. ResultsA total of 538 patients were screened, and after propensity score-matching, a total of 229 pairs (458 patients) were matched, with an average age of 53.9 years and 69.4% (318/458) females. A total of 118 (25.8%) patients had PPCs during hospitalization after surgery, including 60 (26.2%) patients in the PEEP 5 cm H2O group and 58 (25.3%) patients in the PEEP 10 cm H2O group, with no statistically significant difference between the two groups [OR=0.997, 95%CI (0.495, 1.926), P=0.915]. Multivariate logistic regression analysis showed that PEEP was not an independent risk factor for PPCs [OR=0.920, 95%CI (0.587, 1.441), P=0.715]. ConclusionFor patients undergoing thoracoscopic lung surgery, intraoperative PEEP (5 cm H2O or 10 cm H2O) is not associated with the risk of PPCs during hospitalization after surgery, which needs to be further verified by prospective, large-sample randomized controlled studies.
Objectives To systematically review the influence of positive margin on outcome after partial nephrectomy (PN). Methods CCRCT, PubMed, EMbase, Sinomed, WanFang Data and CNKI databases were electronically searched to collect clinical studies on influence of positive margin on outcome after PN from inception to December 31st, 2019. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies, then, meta-analysis was performed by using RevMan 5.4 software. Results A total of 22 cohort studies involving 20 822 patients were included. The results of meta-analysis showed that positive margin after PN could increase the rate of postoperative local recurrence (OR=4.18, 95%CI 2.88 to 6.05, P<0.000 01), distant metastasis (OR=5.28, 95%CI 2.84 to 9.81,P<0.000 01) and total mortality (OR=1.54, 95%CI 1.19 to 1.99,P=0.0010). However, there were no differences on overall survival (OR=0.64, 95% CI 0.34 to 1.19, P=0.16), distant metastasis free survival (OR=0.70, 95%CI 0.26 to 1.84, P=0.46), cancer specific survival (OR=0.43, 95% CI 0.06 to 3.01, P=0.40) and disease-free survival (OR=0.81, 95%CI 0.35 to 1.85, P=0.61) between two groups. Conclusions Current evidence suggests that positive margin after PN may be associated with tumor progression, however, it may not affect patient survival. Due to limited quality and quantity of the included studies, more high quality studies are required to verify above conclusions.