Effect of High Frequency Oscillatory Ventilation on EVLW and Lung Capillary Permeability of Piglets with Acute Respiratory Distress Syndrome Caused by Pulmonary and Extrapulmonary Insults

The effect of high frequency oscillatory ventilation（HFOV） at early stage on hemodynamic parameters, extravascular lung water（EVLW）, lung capillary permeability, CC16 and s ICAM-1 in piglets with pulmonary or extrapulmonary acute respiratory distress syndrome（ARDS） was explored. Central vein pressure（CVP） and pulse indicator continuous cardiac output（Pi CCO） were monitored in 12 anesthetized and intubated healthy piglets. Pulmonary ARDS（ARDSp） and extrapulmonary ARDS（ARDSexp） models were respectively established by lung lavage of saline solution and intravenous injection of oleic acid. Then the piglets received HFOV for 4 h. EVLW index（EVLWI）, EVLW/intratroracic blood volume（ITBV） and pulmonary vascular permeability index（PVPI） were measured before and after modeling（T0 and T1）, and T2（1 h）, T3（2 h）, T4（3 h） and T5（4 h） after HFOV. CC16 and s ICAM-1 were also detected at T1 and T5. Results showed at T1, T3, T4 and T5, EVLWI was increased more significantly in ARDSp group than in ARDSexp group（P〈0.05）. The EVLWI in ARDSp group was increased at T1（P=0.008）, and sustained continuously within 2 h（P=0.679, P=0.216）, but decreased at T4（P=0.007） and T5（P=0.037）. The EVLWI in ARDSexp group was also increased at T1（P=0.003）, but significantly decreased at T3（P=0.002） and T4（P=0.019）. PVPI was increased after modeling in both two groups（P=0.004, P=0.012）, but there was no significant change within 4 h（T5） under HFOV in ARDSp group, while PVPI showed the increasing trends at first, then decreased in ARDSexp group after HFOV. The changes of EVLW/ITBV were similar to those of PVPI. No significant differences were found in ΔEVLWI（P=0.13）, ΔPVPI（P=0.28） and ΔEVLW/ITBV between the two groups（P=0.63）. The significant decreases in both CC16 and s ICAM-1 were found in both two groups 4 h after HFOV, but there was no significant difference between the two groups. It was concluded that EVLWI and lung capillary permeability were markedly increased in ARDSp and ARDSexp groups. EVLW could be decreased 4 h after the HFOV treatment. HFOV, EVLW/ITBV and PVPI were increased slightly at first, and then decreased in ARDSexp group, while in ARDSp group no significant difference was found after modeling. No significant differences were found in the decreases in EVLW and lung capillary permeability 4 h after HFOV.

Correlation analysis of five factors influencing minute volume during high frequency jet ventilation on lung modal: a laboratory study

Five factors influencing minute volume during high frequency jet ventilation were studied on lung modal by stepwise regression analysis. Among these factors, driving pressure is of the greatest dominance. Others are inspiratory and expiratory time ratio, tube diameter, frequency of ventilation and needle distanee, in the order of their impact. A formula was also developed for predicting the parameters.The result is quite satisfactory.

Carbon Dioxide Levels When Starting High Frequency Ventilation in Neonates

Objective: High-frequency ventilation (HFV) is an effective means to achieve gas exchange in neonates. Adequate carbon dioxide (pCO2) levels are best achieved immediately after starting HFV, avoiding either hypercapnia or hypocapnia. We aimed to determine the initial pCO2 levels after starting HFV, and the time taken to obtain the initial blood gas. Methods: We conducted an observational retrospective study on neonates that required their first episode of HFV. Data included the first blood gas result after starting HFV and when the gas was taken after starting HFV. Results: This study included 112 neonates with a median birth weight of 938 (IQR: 692 - 1549) grams and gestational age of 27.2 (24.6 - 30.7) weeks. The first pCO2 after starting HFV (mean (SD)) was 53.7 (22) mmHg. Of 112, 15 (13.4%) showed initial hypocapnia (pCO2 35 mmHg), and 17 (15.2%) showed hypercapnia (pCO2 > 65 mmHg)—a total of 28.6% unacceptable pCO2 levels. Of 112, the first blood gas was obtained within 30 minutes in 47 (42%) and within one hour in 85 (76%), with a significant delay of two or more hours in eight (7.1%). Conclusion: Many neonates had unacceptable pCO2 levels upon starting first-time HFV. There were significant delays in obtaining the initial gas.

Effect of Acute Low Temperature Stress on Oxygen Consumption Rate and Respiration Frequency in Silurus meridionalis and Pelteobag vachelli

The objective of the study was to explore the effect of acute low temperature stress on VO2 and Vf of Silurus meridionalis and Pelteobag vachelli after 10 minutes cold water bath with different temperature.The investigation was operated under the temperature of 24 ℃.It was found that the VO2 and Vf of Silurus meridionalis after 6 and 0 ℃ stress showed a decrease-increase-decrease trend while other groups showed a rapid increase then slowly recovery trend.The VO2 and Vf of Pelteobag vachelli after 0 ℃stress showed a decrease-increase-decrease trend while other groups showed an increase then slowly recovery process.It was suggested that Pelteobag vachelli was more adaptive to acute cold stress,but it cost more energy adapting to cold stress compared to Silurus meridionalis.

Preliminary Validation of Transcutaneous CO₂Monitoring in Patients Undergoing Cardiac Ablation Using Jet Ventilation

Objectives: There is no data in the current medical literature on efficacy or accuracy of transcutaneous (tcPCO2) monitoring during jet ventilation for cardiac ablation. The use of tcPCO2 during cardiac ablation procedures offers the opportunity to compare end-tidal and transcutaneous methods of CO2 measurement before and after the use of the jet ventilation. Comparison of these measurements with arterial blood gas CO2 levels allows evaluation of the accuracy of the tcPCO2 technique for use during jet ventilation. Design: Observational study;patients served as their own controls. Setting: Cardiac electrophysiology laboratory. Participants: 15 adult patients (9 M), ASA III-IV, aged 26 to 82 years (median 66 years) undergoing radiofrequency ablation for atrial fibrillation. Interventions: Jet ventilation (JV) versus conventional ventilation. Measurements and Main Results: Paired measurements of end-tidal CO2 (EtCO2) and transcutaneous CO2 (tcPCO2) were recorded during periods of conventional ventilation. Paired measurements of arterial blood CO2 (PaCO2) levels and tcPCO2 were recorded during JV. ABG samples were drawn at the anesthesiologist’s discretion to assess the patient’s respiratory status. The level of agreement between the three methods was compared using the Bland Altman plot. We found that tcPCO2 values consistently provided a close approximation to PaCO2 levels. The mean difference between tcPCO2 and EtCO2 values in baseline and post-JV was on the order of 3 - 5 mmHg, with standard deviation of 4 - 6 mmHg. This is well within the range of variability that is accepted in clinical practice. Conclusions: These preliminary results suggest that tcPCO2 provides an acceptable estimate of CO2 concentration in arterial blood during JV, as well as prior to and following JV.

基于自适应准谐振控制的变频器并联VF开环均流控制策略

针对采用VF开环控制的变频器机组并联中出现的环流问题,提出了一种引入频率自适应准谐振控制器的VF开环控制策略,利用准谐振控制器在谐振频率处增益无穷大的特点消除系统不平衡扰动分量,同时根据电机负载的输出频率时变的特性,构建了频率自适应的准谐振控制器。仿真和实验证明,在保留VF开环控制对负载强适应性的基础上,该策略能很好的实现变频器机组并联均流控制。

Effects of high-frequency oscillatory ventilation and conventional mechanical ventilation on oxygen metabolism and tissue perfusion in sheep models of acute respiratory distress syndrome

Background High-frequency oscillatory ventilation （HFOV） allows for small tidal volumes at mean airway pressures （mPaw） above that of conventional mechanical ventilation （CMV）,but the effect of HFOV on hemodynamics,oxygen metabolism,and tissue perfusion in acute respiratory distress syndrome （ARDS） remains unclear.We investigated the effects of HFOV and CMV in sheep models with ARDS.Methods After inducing ARDS by repeated lavage,twelve adult sheep were randomly divided into a HFOV or CMV group.After stabilization,standard lung recruitments （40 cmH2O × 40 seconds） were performed.The optimal mPaw or positive end-expiratory pressure was obtained by lung recruitment and decremental positive end-expiratory pressure titration.The animals were then ventilated for 4 hours.The hemodynamics,tissue perfusion （superior mesenteric artery blood flow,pHi,and Pg-aCO2）,oxygen metabolism and respiratory mechanics were examined at baseline before saline lavage,in the ARDS model,after model stabilization,and during hourly mechanical ventilation for up to 4 hours.A two-way repeated measures analysis of variance was applied to evaluate differences between the groups.Results The titrated mPaw was higher and the tidal volumes lower in the HFOV group than the positive end-expiratory pressure in the CMV group.There was no significant difference in hemodynamic parameters between the HFOV and CMV groups.There was no difference in the mean alveolar pressure between the two groups.After lung recruitment,both groups showed an improvement in the oxygenation,oxygen delivery,and DO2.Lactate levels increased in both groups after inducing the ARDS model.Compared with the CMV group,the superior mesenteric artery blood flow and pHi were significantly higher in the HFOV group,but the Pg-aCO2 decreased in the HFOV group.Conclusion Compared with CMV,HFOV with optimal mPaw has no significant side effect on hemodynamics or oxygen metabolism,and increases gastric tissue blood perfusion.

Gas Exchange Mechanism of High Frequency Ventilation:A Brief Narrative Review and Prospect

The high frequency ventilation(HFV)can well support the breathing of respiratory patient with 20%-40%of normal tidal volume.Now as a therapy of rescue ventilation when conversional ventilation failed,the HFV has been applied in the treatments of severe patients with acute respiratory failure(ARF),acute respiratory distress syndrome(ARDS),etc.However,the gas exchange mechanism(GEM)of HFV is still not fully understood by researchers.In this paper,the GEM of HFV is reviewed to track the studies in the last decades and prospect for the next likely studies.And inspired by previous studies,the GEM of HFV is suggested to be continually developed with various hypotheses which will be testified in simulation,experiment and clinic trail.One of the significant measures is to study the GEM of HFV under the cross-disciplinary integration of medicine and engineering.Fully understanding the GEM can theoretically support and expand the applications of HFV,and is helpful in investigating the potential indications and contraindications of HFV.

基于VFVA技术的地铁通风系统的研究

地铁已经成为城市交通最重要的组成部分，但巨大的能耗成为制约其发展的主要因素。本文通过对地铁通风系统的研究，提出了变频变风控制技术在地铁通风系统中应用，不仅有效提高了通风效果，而且大大节约了地铁系统能耗。

基于PS-VF-TBD的地波雷达船只目标航迹起始方法

针对地波雷达低信噪比目标信号“闪烁”导致的航迹起始困难问题,本文提出了一种基于PS-VF-TBD的航迹起始方法。该方法综合利用了地波雷达回波谱中目标信号的展宽特征和运动特性,利用PS-VF-TBD方法对运动目标能量有效积累的特点,提高对疑似目标多帧信号间的关联概率,进而提高对真实目标的搜索概率和航迹起始成功率。通过地波雷达实测数据的航迹起始结果及长时间跟踪结果与同步AIS信息的对比分析,表明本文提出的方法相对于基于DP-TBD的航迹起始方法可以给出更好的航迹起始结果,提高了远端低信噪比下“闪烁”目标的航迹起始概率,可提高目标跟踪性能,并具有区分距离-多普勒谱中邻近目标的能力。

High-frequency jet ventilation for right upper pulmonary lobe sleeve resection

Hypoxemia during one-lung ventilation （OLV） is normal. Different ways of improving SpO2 on OLV include intermittent inflation ot the collapsed lung with oxygen, lung recruitment, and application of continuous positive airway pressure （CPAP） to the nondependent lung. This case report described the use of CPAP to the right lung, which was converted to high-frequency jet ventilation （HFJV） of the middle and lower lobes during fight upper lobe sleeve resection.

锦屏复杂地下洞室施工通风智能调控研究

锦屏大设施具有多洞室、多工作面,通风网络复杂等特点,为确保洞室空气质量并解决施工期通风高能耗问题,通过优化隧道需风量计算方法,确定风压阻力损失,进行施工通风计算。根据风机布设位置,划分供排风区域,明确了风机控制区域;基于各区域风量、风压,得出了风机运行功率计算式并细分风机档位,形成了地下洞室施工期风机变频调节策略;通过布设空气质量监测设备,建立了软件平台,可视化远程控制地下洞室空气质量,自动监测、处理数据指导变频器控制风机变频,并利用污染物浓度监测数据验证了变频通风有效性。研究结果表明:1)风机运行频率可随洞室内污染物浓度及时变化;2)通风智能调控可有效降低污染物浓度;3)通风智能调控可降低施工通风能耗,实现施工期智能化通风。

带针胸管胸腔闭式引流术联合高频机械通气治疗新生儿气胸的临床效果

目的:分析带针胸管胸腔闭式引流术联合高频机械通气(HFOV)治疗新生儿气胸的临床效果及安全性。方法:选取2022年1月—2023年12月昆明市第一人民医院收治的新生儿气胸患儿62例为研究对象,随机分为对照组和观察组,各31例。对照组实施传统胸腔闭式引流术联合常频机械通气治疗,观察组实施带针胸管胸腔闭式引流术联合HFOV治疗。比较两组治疗效果、血气分析指标、治疗指标及并发症发生率。结果:观察组治疗总有效率高于对照组,差异有统计学意义(P=0.006);治疗12 h后,两组动脉血氧分压、动脉血二氧化碳分压、氧合指数、吸入氧浓度优于治疗前,观察组优于对照组,差异有统计学意义(P<0.05);观察组操作时间、起效时间、呼吸机参数下调时间、胸部X线恢复正常时间、住院时间短于对照组,伤口直径小于对照组,差异有统计学意义(P<0.05);观察组并发症发生率低于对照组,差异有统计学意义(P=0.005)。结论:带针胸管胸腔闭式引流术联合HFOV治疗新生儿气胸的效果显著,可改善新生儿血气分析指标,缩短病情转归时间,安全性较高。

不同无创通气法治疗早产儿呼吸窘迫综合征的效果比较

目的比较无创高频振荡通气(NHFOV)、经鼻间歇正压通气(NIPPV)疗法、经鼻持续气道正压通气(NCPAP)治疗早产儿呼吸窘迫综合征(RDS)的效果。方法选取2021年1月至2022年12月贵港市人民医院收治的150例RDS早产儿,采用抽签法分为三组,每组各50例,分别给予NHFOV、NIPPV、NCPAP。比较三组呼吸情况与用氧情况、撤机成功率、血气指标、并发症发生情况。结果三组的无创呼吸时间、总用氧时间比较,差异无统计学意义(P>0.05)。NHFOV组的撤机成功率较高(P<0.05)。治疗前,三组血气指标比较,差异无统计学意义(P>0.05);治疗后,三组动脉血二氧化碳分压(PaCO_(2))、动脉血氧分压(PaO_(2))、氧合指数(P/F)比较,差异有统计学意义(P<0.05),NHFOV组的PaCO_(2)低于NIPPV组和NCPAP组,PaO_(2)、P/F高于NIPPV组和NCPAP组(P<0.05);三组pH值比较,差异无统计学意义(P>0.05)。三组并发症总发生率比较,差异无统计学意义(P>0.05)。结论与NIPPV、NCPAP相比,NHFOV可提升RDS早产儿撤机成功率,促进血气指标恢复。

地下综合管廊燃气泄漏数值模拟研究

为研究燃气在地下综合管廊内不同几何结构顶部泄漏和扩散情况,通过Ansys Fluent软件建立拱顶、尖顶和平顶3种结构的管廊燃气泄漏数值模拟模型,分析燃气在不同结构管廊内的扩散规律。研究结果表明:管廊结构会影响燃气扩散情况,泄漏后燃气倾向于向管廊顶部积聚;燃气分层与管廊结构相关,其中拱顶结构分层相比尖顶和平顶更稳定;管廊结构会影响燃气扩散速度,其中拱顶结构内扩散速率相对最低,该结构可降低爆炸风险;本文管廊扩散预测模型的最大相对误差为4.57%,该模型能较准确预测燃气泄漏扩散情况。研究结果可为地下管廊的安全性研究提供一定参考。

经鼻无创高频振荡通气在治疗婴幼儿重症肺炎方面的临床应用

目的通过经鼻无创高频振荡通气(Nasal non-invasive high frequency oscillatory ventilation,n HFOV)与经鼻持续气道正压通气(nasal continuous positive airway pressure n CPAP)这两种通气模式在婴幼儿重症肺炎中的无创辅助通气,探究初始治疗中的临床效果及并发症的发生。方法选取2020.06至2022.06在新生儿重症监护病房(neonatal intensive care unit,NICU)住院的合并呼吸衰竭的婴幼儿肺炎(14d-3m)57例,随机分为观察组(n HFOV组)(27例)及对照组(n CPAP组)(30例);比较两组患儿在无创呼吸机治疗4-6小时后的相关血气分析数据变化,治疗的成功率,上机时间,二氧化碳变化率及各种不良反应的发生率。结果n HFOV组和n CPAP组相比,n HFOV组初始治疗的成功率,呼吸机应用时间,喂养不耐受及心动过速发生率,治疗6小时后PCO_(2)变化率,经统计学分析,均有明显差异,(P<0.05)差异有统计学意义;在鼻中隔损伤、消化道出血等并发症的发生率方面,经统计学分析,差异无统计学意义。结论n HFOV作为婴幼儿重症肺炎的初始无创通气模式,n HFOV临床应用效果明显优于n CPAP,在喂养不耐受及心动过速等并发症发生率方面有明显的差异,可以作为一种创伤性小的无创通气模式,应用于婴幼儿重症肺炎的治疗中,从而最大限度地避免了有创机械通气的应用,减少相关并发症的发生。

经鼻无创高频振荡通气联合TcPCO_(2)和TcPO_(2)监测在早产儿呼吸窘迫综合征中的应用

目的分析经鼻无创高频震荡通气联合经皮二氧化碳分压(TcPCO_(2))和经皮氧分压(TcPO_(2))监测在早产儿呼吸窘迫综合征中的应用。方法选择2019年10月至2021年10月收治的新生儿呼吸窘迫综合征无创呼吸支持治疗的早产儿80例,采用随机数字法分为改良组(经鼻无创高频震荡通气)和对照组(经鼻持续正压通气)。每组40例。2组均联合TcPCO_(2)和TcPO_(2)监测。观察2组通气0、6、12、24 h后的pH值、TcPCO_(2)/TcPO_(2)指标、无创通气时间、治疗失败转为气管插管机械通气率、并发症发生率及病死率。结果通气0 h,2组血液pH值、TcPCO_(2)、TcPO_(2)比较差异无统计学意义(P>0.05);与对照组比较,改良组通气6、12、24 h血液pH值、TcPO_(2)均明显升高,TcPCO_(2)均明显降低(P<0.05)。与对照组比较,无创通气时间和治疗失败转为气管插管机械通气率均明显降低(P<0.05)。2组气漏、腹胀、鼻部损伤、肺出血、感染性肺炎等并发症发生率比较差异无统计学意义(P>0.05)。对照组病死率为5.00%(2/40),改良组病死率为2.50%(1/40),差异无统计学意义(P>0.05)。结论经鼻无创高频震荡通气联合TcPCO_(2)和TcPO_(2)监测在早产儿呼吸窘迫综合征中应用价值较高,可改善患儿呼吸功能,降低气管插管机械通气率,且不会增加并发症的发生。

嵌入式风冷变频器散热结构设计及热仿真分析研究

矿用变频器作为矿井通风系统的重要装置,其散热性能将影响煤矿的安全生产。为便于井下安装调试,当前矿用变频器要求更大功率体积比。为解决上述问题,提出了一种适用于局部通风机的嵌入式风冷变频器结构,利用风机工作风流,以强迫风冷的方式进行变频器散热。以常规型散热翅片为基础,设计了等腰三角形与圆弧形结构散热翅片,分别进行了三维建模及结温理论计算,使用有限元法对3种模型进行数值模拟,并对IGBT模块的温度场和矢量场进行分析。结果表明:数值模拟与理论计算结果的误差不超过5%;翅片间距越小,气流损失越严重,等腰三角形和圆弧形翅片下的流动损失问题得到更好的解决;圆弧形翅片的间距小但通过增大翅片与流体的对流换热面积提升了散热性能。散热性能最优的圆弧形散热翅片在翅片间距不变,翅片高度和厚度分别为105 mm和5 mm时,散热性能达到最佳。

兼顾降噪和通风性能的声学超材料研究进展

传统用于隔声降噪的结构,通常阻碍了气流的传输,无法满足许多实际应用场景的需求。声学超材料作为当下声学研究的热点,为设计新颖的通风降噪结构提供了有效的解决方案。简要讨论了传统通风降噪结构在应用中的局限性,追溯了声学超材料的出现与发展,重点介绍了Helmholtz共振结构、空间盘绕结构、声学超笼和声传输可调结构这几种类型的声学超材料在通风和降噪方面应用的最新进展,总结了这些超材料的结构特点、降噪原理和通风特性,以及它们在低频宽带噪声衰减、通风效果和结构轻薄化等方面的明显优势。最后,对这一新兴领域在优化设计、现场实验和通风性能研究三个方面的发展进行了展望。