Effects of unilateral superimposed high-frequency jet ventilation on porcine hemodynamics and gas exchange during one-lung flooding

BACKGROUND Superimposed high-frequency jet ventilation(SHFJV)is suitable for respiratory motion reduction and essential for effective lung tumor ablation.Fluid filling of the target lung wing one-lung flooding(OLF)is necessary for therapeutic ultrasound applications.However,whether unilateral SHFJV allows adequate hemodynamics and gas exchange is unclear.AIM To compared SHFJV with pressure-controlled ventilation(PCV)during OLF by assessing hemodynamics and gas exchange in different animal positions.METHODS SHFJV or PCV was used alternatingly to ventilate the non-flooded lungs of the 12 anesthetized pigs during OLF.The animal positions were changed from left lateral position to supine position(SP)to right lateral position(RLP)every 30 min.In each position,ventilation was maintained for 15 min in both modalities.Hemodynamic variables and arterial blood gas levels were repeatedly measured.RESULTS Unilateral SHFJV led to lower carbon dioxide removal than PCV without abnormally elevated carbon dioxide levels.SHFJV slightly decreased oxygenation in SP and RLP compared with PCV;the lowest values of PaO_(2) and PaO_(2)/FiO_(2) ratio were found in SP[13.0;interquartile range(IQR):12.6-5.6 and 32.5(IQR:31.5-38.9)kPa].Conversely,during SHFJV,the shunt fraction was higher in all animal positions(highest in the RLP:0.30).CONCLUSION In porcine model,unilateral SHFJV may provide adequate ventilation in different animal positions during OLF.Lower oxygenation and CO_(2) removal rates compared to PCV did not lead to hypoxia or hypercapnia.SHFJV can be safely used for lung tumor ablation to minimize ventilation-induced lung motion.

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.

Supraglottic jet oxygenation and ventilation(SJOV) for resuscitation of injured soldiers and people in war field

Dear Editor,Soldiers or people in battlefield settings are frequently injured with acute trauma, resulting in respiratory depression, hypoxia and associated morbidity and mortality. Traumatic brain injury(TBI) is with as much as 80%–90% of mild to moderate in combat casualties and contributed significantly to morbidity and mortality in battlefield settings. Correction of hypoxia at as capable as possible is expected to reduce or minimize the morbidity/mortality due to acute brain injury. An easy, quick and safe setup to promote oxygenation/ventilation of injured military personnel or peoples by non-medical personnel in battlefield settings immediately after acute injury before transfer to hospital is expected to reduce the morbidity/mortality due to injury mediated respiratory depression.

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

Ｃｏｒｒｅｌａｔｉｏｎａｎａｌｙｓｉｓｏｆｆｉｖｅｆａｃｔｏｒｓｉｎｆｌｕｅｎｃｉｎｇｍｉｎｕｔｅｖｏｌｕｍｅｄｕｒｉｎｇｈｉｇｈｆｒｅｑｕｅｎｃｙｊｅｔｖｅｎｔｉｌａｔｉｏｎｏｎｌｕｎｇｍｏｄａｌ：ａｌａｂｏｒａｔｏｒｙ ｓｔｕｄｙＣｈｅｎＭｉｎ（...

Prediction Analysis on the Transport Distance of Supply Air in Warm Air Heating Room with Impinging Jet Ventilation Systems

To overcome the disadvantages of displacement ventilation( DV) and traditional mixing ventilation( MV) system,a new ventilation system known as impinging jet ventilation system( IJVS)has been developing. The warm air can be supplied with impinging jet ventilation( IJV), while the DV is only used for cooling.However,the flow and temperature field of IJV under heating scenario has had few references. The paper is mainly focused on computational fluid dynamics( CFD) and developing an adequate correlation between the distance L that warm air can reach and different parameters in the warm IJVS by using response surface methodology( RSM). The results indicate that L decreases as the supply velocity υ decreases but increases as the supply temperature difference ΔT or the discharge height h decreases. In the variable air volume( VAV) system, it is necessary to determine supply parameters both under the maximum-heat-load condition and the small-heat-load condition. Unlike the VAV system,the constant air volume( CAV) system has no need to study the small-heat-load condition. Draught discomfort near the nozzle becomes the issue of concern in IJVS, thus the suitable discharge height is of great importance in design and can be calculated based on the predictive model.

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.

Ventilatory effect of normal frequency jet ventilation in non-intubated anesthesia in the treatment of the palmar hyperhidrosis

Objective: To evaluate the ventilatory effect of normal frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the palmar hyperhidrosis (PH). Methods: 62 patients with PH undergoing video-assisted thoracoscopic sympathectomy, aged 18~35 years, ASA I-II, were randomized into two groups: intubated group (group T) and normal-frequency jet ventilation group (group J). After induction tracheal tubes were inserted in Group T and Wei nasal airway were inserted in group J. The heart rate(HR),saturation pulse oxygen (SPO2), mean artery pressure (MAP) and end-tidal carbon dioxide partial pressure (PETCO2) were recorded at following time points: before induction (T0),1 min after induction (T1), 1 min after tube insertion/ intubation (T2), when trocars were inserted and carbon dioxide was inflated (T3), during lung recruitment maneuver and the chest closure (T4), the moment of extubation (T5), 15 min after extubation (T6). Blood samples were taken from left radial artery for blood gas analysis to monitor carbon dioxide partial pressure, arterial oxygen partial pressure, PH ,the BE at T0, T4, T6.The duration of anesthesia, awaking time ,the dosage of the propofol and the remifentanil, the intraoperative and postoperative adverse events were recorded. Results: Compared with group T, the HR and MAP were more stable in group J. The awaking time in the group J were significantly shorter than those in group T (P<0.05), the dosage of the remifentanil in group J was significantly less than that in group T (P<0.05), The incidences of throat discomfort, nausea and vomiting were lower than those in group T (P<0.05). Conclusion: Normal-frequency jet ventilation via Wei jet nasal airway in non-intubated anesthesia in the treatment of the (PH)is feasible, which can reduce stress response and make hemodynamics stable without the complications of tracheal intubation.

Preparation of novel Ni-Ir/γ-Al_2O_3 catalyst via high-frequency cold plasma direct reduction process

The novel Ni-Ir/γ-Al2O3 catalyst, denoted as NIA-P, was prepared by high-frequency cold plasma direct reduction method under ambient conditions without thermal treatment, and the conventional sample, denoted as NIA-CR, was prepared by impregnation, thermal calcination, and then by H2 reduction method. The effects of reduction methods on the catalysts for ammonia decomposition were studied, and they were characterized by XRD, N2 adsorption, XPS, and H2-TPD. It was found that the plasma-reduced NIA-P sample showed a better catalytic performance, over which ammonia conversion was 68.9%, at T = 450℃, P = 1 atm, and GHSV = 30, 000 h^-1. It was 31.7% higher than that of the conventional NIA-CR sample. XRD results showed that the crystallite size decreased for the sample with plasma reduction, and the dispersion of active components was improved. There were more active components on the surface of the NIA-P sample from the XPS results. This effect resulted in the higher activity for decomposition of ammonia. Meanwhile, the plasma process significantly decreased the time of preparing catalyst.

Numerical Study of the Transition Between Reentrant Jet and Twin Vortex Flow Regimes in Ventilated Cavitation

Contrary to natural cavitation,ventilated cavitation is controllable and is not harmful.It is particularly used to reduce the drag of the hydraulic vehicles.The ventilated cavitation is characterized by various gas regimes.The mechanisms of ventilated cavitation are investigated in the present work with CFD based on a 2D solver.The attention is especially focused on the transition between the reentrant jet and twin vortex regimes.The results confirmthat the product of ventilated cavitation number and Froude number is lower than 1(σcFr<1)in the twin vortex regime,while it is higher than 1(σcFr>1)in the reentrant jet regime,as reported in the literature.Further analysis shows that ventilated cavitation is significantly influenced by the natural cavitation number.

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.

水下平板通气减阻特性研究

为了研究通气射流对水下平板阻力特性的影响,本文采用Mixture多相流模型和Realizable k-ε湍流模型研究了三维水下平板通气射流的流动结构特征,得到了水下平板表面气液流场结构和减阻特性。数值结果表明:气体注入后,受来流影响而紧贴壁面向下游发展。当气体稳定覆盖在平板壁面后,平板阻力系数较不通气情况降低了16.73%。另外,因气体注入壁面边界层后,提升了壁面上的速度梯度,降低了壁面流体粘性系数;在气膜覆盖区(α_(l)>80%),因流体粘性系数的下降量远大于速度梯度的上升量,使流体粘性系数对气膜核心区内的减阻率起决定性作用;对于远离气膜核心区外的壁面,切向速度梯度对摩擦阻力系数的贡献增强。

基于GA-BP神经网络和改进粒子群算法的碰撞射流和冷却顶板复合空调系统优化

对碰撞射流和辐射顶板(IJV/RC)复合空调在不同室内负荷条件下运行时的室内热环境进行数值模拟,基于遗传算法-反馈(GA-BP)神经网络建立运行性能(吹风感R_(PD),头足温差Δt,空气交换效率e ACE,工作区平均温度t_(a))与设计变量(送风温度t_(s)、送风速度v_(s)、冷却顶板内表面温度t_(c)、房间负荷Q_(c))之间的预测模型,通过相关性分析确定设计变量对运行性能影响的显著性并排序。结果表明,增大v_(s)可使Δt降低,但R_(PD)增大;增大t_(c)有助于降低Δt和R_(PD),但t_(a)升高;为使t_(a)下降,可通过降低t_(s)来实现,但室内空气质量变差。为确保IJV/RC复合空调能在保证室内热舒适的同时提供良好室内空气品质,利用改进粒子群算法对复合空调的运行性能进行多目标同时优化,建立不同房间负荷条件下的设计参量最优匹配关系。研究结果可为IJV/RC复合空调的优化设计和运行控制提供理论指导。

综合管廊电缆舱基于射流风机的局部通风方法研究

地下综合管廊长建设里程需求,廊内增设防火门使其电缆舱内的通风散热问题变得十分严峻.长度越长,管廊温度会逐渐升高,防火门增加会在管廊角落等狭小空间形成高温聚集区,均会阻碍管廊散热.采用局部通风的手段,目的是以较小的风量排除温度异常点,降低管廊全局通风换气量.运用数值模拟结合实验验证的手段对常规电缆舱与局部通风电缆舱在不同边界条件下进行比较,分析了局部通风策略的降温规律.结果表明:在同一总风量比例下增加换气次数可以强化风机控制区域的换热效果,且由于管廊总风量会与风机局部风量相互影响,一味增加总风量比例并不能明显改善管廊内温度分布.利用局部通风方法,电缆舱内降温幅度进一步增大,在局部区域会比常规电缆舱温度低2.58℃.局部通风方法能以较小的风量冷量达到与常规工况相似的降温效果,具备一定的节能优势.

带上盖开发隧道通风流场特性及射流风机偏转角度研究

带上盖开发的隧道结构复杂,通风流场紊乱,隧道运营通风能力难以得到保障。揭示这类隧道的通风流场特性,优化隧道风机布置参数具有重要意义。以广州市某珠江过江隧道工程为背景,利用数值模拟方法,探究不同风机偏转台数、偏转角度工况下隧道通风流场特性、风机升压能力。结果表明:带上盖开发隧道风机安装位置受限、复杂结构通风阻力大,导致隧道通风流场分布不均,风机升压能力较差,风机难以提供可靠的运营通风能力;带上盖开发隧道设置3台吊顶式风机时,通过合理的设置风机偏转台数和风机偏转角度,能够稳定隧道通风流场,提高平均风速,优化隧道内通风效果;当3台吊顶式风机全部偏转布置或风机偏转角度大于5°时,虽能增大未安装风机一侧的通风风速,但会导致射流分布不均,安装风机一侧风速降低,过多射流偏转也将携带更多动能撞击隧道壁面,导致射流遭受的能量损失增大,不利于隧道通风流场的稳定;采用2台吊顶式风机偏转2°~5°布置时,此时隧道内流场分布均匀,射流风机升压系数为0.7~0.8,隧道内风机射流阻力损失约28~29 Pa,可提升风机升压力,减小风机射流阻力损失,利于带上盖开发的隧道运营通风。研究结果可为优化带上盖开发隧道射流风机布置方式和保障运营通风效果提供参考。

声门上喷射通气技术在舒适化诊疗中的应用进展

低氧血症是无痛胃肠镜、无痛人工流产术、无痛经内镜逆行胰胆管造影和无痛纤维支气管镜等舒适化诊疗期间最常见的不良事件,并且严重低氧血症会造成心、脑意外事件,因此如何预防和减少低氧血症的发生至关重要。声门上喷射通气(SJV)技术是一种新型、无创的非气管插管的通气方式。气流起源于声门上,在低压下经过喷射导管喷入患者的气道内,可以为缺氧风险较高和发生低氧血症的患者提供持续且有效的供氧,适于临床危重症患者短时间使用,广泛应用于临床各种舒适化诊疗中。但目前关于SJV技术的研究较少,仍缺乏大型的多中心临床试验验证其疗效,且对于SJV技术的应用尚无公认的使用标准和治疗指南。

对撞射流下通风空间的流场结构实验研究

为了研究送风口和回风口位置对室内流场结构的影响,本文搭建了采用多条缝对置撞击送风的通风缩比模型实验平台,利用激光粒子测速技术研究了等温和非等温工况下多条缝通风空间中不稳定气流场的速度和湍流信息。结果表明:等温和非等温工况下,送风口截面的流场速度、湍动能和涡量的空间分布类似,最大值分别可以达到1.3 m/s、0.1 m^(2)/s~2和60 s^(-1),射流碰撞形成2个大尺度涡旋,造成流场结构不稳定;CS4.5截面,流场速度、湍动能和涡量最大值分别可以达到0.9 m/s、0.04 m^(2)/s~2和30 s^(-1);CS3.5截面,速度与涡量最大值均出现在近壁面附近,分别为0.42 m/s、8 s^(-1),湍动能最大值出现在截面中间位置,为0.13 m^(2)/s~2,且流场中形成了大规模的涡旋;非等温工况下,送风口截面和CS3.5截面中小尺度涡旋增加,大尺度涡旋减少,热羽流抑制了大尺度流场结构,增加了小尺度流场结构。

Numerical investigation of impinging jet ventilation in ICUs:Is thermal stratification a problem?

Intensive care units(ICUs)are the high incidence sites of hospital-acquired infections,where impinging jet ventilation(IJV)shows great potential.Thermal stratification of IJV and its effect on contaminants distribution were systematically investigated in this study.By changing the setting of heat source or the air change rates,the main driving force of supply airflow can be transformed between thermal buoyancy and inertial force,which can be quantitatively described by the dimensionless buoyant jet length scale(l_(m)^(-)).For the investigated air change rates,namely 2 ACH to 12 ACH,l_(m)^(-)varies between 0.20 and 2.80.The thermal buoyancy plays a dominant role in the movement of the horizontally exhaled airflow by the infector under low air change rate,where the temperature gradient is up to 2.45℃/m.The flow center remains close to the breathing zone of the susceptible ahead,resulting into the highest exposure risk(6.6‰for 10-μm particles).With higher heat flux of four PC monitors(from 0 W to 125.85 W for each monitor),the temperature gradient in ICU rises from 0.22℃/m to 1.02℃/m;however,the average normalized concentration of gaseous contaminants in the occupied zone is reduced from 0.81 to 0.37,because their thermal plumes are also able to carry containments around them to the ceiling-level readily.As the air change rate was increased to 8 ACH(l_(m)^(-)=1.56),high momentum weakened the thermal stratification by reducing the temperature gradient to 0.37℃/m and exhaled flow readily rose above the breathing zone;the intake fraction of susceptible patient located in front of the infector for 10-μm particles reduces to 0.8‰.This study proved the potential application of IJV in ICUs and provides theoretical guidance for its appropriate design.

高速公路隧道通风设计

高速公路隧道通风是高速公路的重要组成部分,其光线变化大、视野不清、空间环境狭窄隧道是高速公路上的特殊路段存在潜在的交通事故危险。对设计要求越来越高,下面就结合凯里环城高速北段通风设计的设计思路和方法进行分析研究。因此以项目通风设计标准、通风设施与其他设施的信息控制、风机的选型等几个方面来作为高速公路隧道通风设计的重点进行分析。

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.

Experimental Study of the Diffusion of a Confined Wall Jet through a Perforated Plate: Influence of the Porosity and the Geometry

This paper investigated lateral diffusion of a confined two-dimensional wall jet (air inlet height: 5 cm) through a perforated plate. We considered two plates with porosities of and . The plates were positioned at distances of 10 cm and 20 cm below the jet inlet. The experiments were realized using 2D Laser Doppler Anemometer (LDA). Different profiles of mean and fluctuating velocities are presented. The presence of a perforated plate strongly modified the airflow pattern compared to an empty enclosure. The velocities above and below the plate depend on several parameters, including the porosity and the plate’s position relative to the inlet slot and the longitudinal position. The difference between the flow velocity above and below the plates could not be related using a universal formula that depends on these parameters. We also investigated the influence of a porous media of a height of 20 cm (a stack of spheres having a diameter of 3.75 cm) located below the perforated plate. The results highlight that the porous medium strengthens the effects of the perforated plate on the flow.