COMPARISON OF HIGH-FREQUENCY OSCILLATION VEN-TILATION WITH CONVENTIONAL MANDATORY VENTILATION IN ANIMAL ARDS MODEL

To compare effect of high-frequency oscillation ventilation （HFOV） and conventional mandatory ventilation （CMV） on lung injury development in rabbit with acute respiratory distress syndrome （ ARDS）. Methods Animals that underwent saline lung lavage to produce lung injury were randomized to one of the two treatment groups （ HFOV or CMV, n =6）. PaCO2 was maintained between 35 -45mmHg and arterial oxygen saturation （ SaO2 ） was maintain 〉 88% by adjusting corresponding ventilator parameters. Ventilation period was 6h. Lung fluids were aspirated before and at the end of ventilation for cell analysis. Then the animals were euthanized, lung tissue was removed for wet/dry weight measurement, light and electron microscopic examination. Besults The difference of artery blood gas analyses（pH, PaO2, PaCO2 ） between HFOV and CMV was insignificant. The difference between HFOV and CMV in cytological examination of lung fluids, wet/dry weight measurement was also insignificant. But compared with CMV, HFOV not only reduced the area of lung injury, but also reduced lung injury score in light and electron microscopic examination. Conclusion When same artery blood gas analysis was obtained, HFOV significantly reduced lung injury development in ARDS animal than CMV. As a lung protection strategy, HFOV can be used in the treatment of ARDS.

Review of the Analysis and Suppression for High-frequency Oscillations of the Grid-connected Wind Power Generation System

High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the grid.Ensuring the WPGS can damp HFO is becoming more and more vital for the development of wind power.The HFO phenomenon of wind turbines under different scenarios usually has different mechanisms.Hence,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical engineering.This paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of technology.Finally,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.

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.

Identification and Analysis of High-Frequency Oscillations in the Eyewalls of Tropical Cyclones

High-frequency oscillations, with periods of about 2 hours, are first identified by applying wavelet analysis to observed minutely wind speeds around the eye and eyewall of tropical cyclones（TCs）. Analysis of a model simulation of Typhoon Hagupit（2008） shows that the oscillations also occur in the TC intensity, vertical motion, convergence activity and air density around the eyewall. Sequences of oscillations in these variables follow a certain order.

Variations in High-frequency Oscillations of Tropical Cyclones over the Western North Pacific

Variations in the high-frequency oscillations of tropical cyclones （TCs） over the western North Pacific （WNP） are studied in numerical model simulations. Power spectrum analysis of maximum wind speeds at 10 m （MWS10） from an ensemble of 15 simulated TCs shows that oscillations are significant for all TCs. The magnitudes of oscillations in MWS10 are similar in the WNP and South China Sea （SCS）; however, the mean of the averaged significant periods in the SCS （1.93 h） is shorter than that in the open water of the WNP （2.83 h）. The shorter period in the SCS is examined through an ensemble of simulations, and a case simulation as well as a sensitivity experiment in which the continent is replaced by ocean for Typhoon Hagupit （2008）. The analysis of the convergence efficiency within the boundary layer suggests that the shorter periods in the SCS are possibly due to the stronger terrain effect, which intensifies convergence through greater friction. The enhanced convergence strengthens the disturbance of the gradient and thermal wind balances, and then contributes to the shorter oscillation periods in the SCS.

A note for the mechanism of high-frequency oscillation instability resulted from absorbing boundary conditions

In this paper the explanation of the mechanism of high-frequency oscillation instability resulted from absorbing boundary conditions is further improved. And we analytically prove the proposition that for one dimensional discrete model of elastic wave motion, the module of reflection factor will be greater than 1 in high frequency band when artificial wave velocity is greater than 1.5 times the ratio of discrete space step to discrete time step. Based on the proof, the frequency band in which instability occurs is discussed in detail, showing such high-frequency waves are meaningless for the numerical simulation of wave motion.

Simulation of wind-induced near-inertial oscillations in a mixed layer near the east coast of Korea in the East/Japan Sea

Using a simple damped slab model, it was possible to show that a local wind induced 88% （15 of 17） of the near-inertial oscillations （NIO） observed in the mixed layer near the east coast of Korea from 1999 to 2004. The model, however, overestimated the energy level in about two-thirds of the simulated cases, because the slab model was forced with winds whose characteristic period was shorter than the damping time scale of the model at 1.5 d. At the observation site, due to typhoons and orographic effects, high-frequency wind forcing is quite common, as is the overestimation of the energy level in the slab model results. In short, a simple slab model with a damping time-scale of about 1.5 d would be enough to show that the local wind was the main energy source of the near-inertial energy in this area, but the model could not be used to accurately estimate the amount of the work done by the wind to the mixed layer.

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.

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.

Prognostic value of high-frequency oscillations combined with multimodal imaging methods for epilepsy surgery

Background:The combination of high-frequency oscillations(HFOs)with single-mode imaging methods has been proved useful in identifying epileptogenic zones,whereas few studies have examined HFOs combined with multimodal imaging methods.The aim of this study was to evaluate the prognostic value of ripples,an HFO subtype with a frequency of 80 to 200 Hz is combined with multimodal imaging methods in predicting epilepsy surgery outcome.Methods:HFOs were analyzed in 21 consecutive medically refractory epilepsy patients who underwent epilepsy surgery.All patients underwent positron emission tomography(PET)and deep electrode implantation for stereo-electroencephalography(SEEG);11 patients underwent magnetoencephalography(MEG).Sensitivity,specificity,positive predictive value,negative predictive value,and accuracy in predicting surgical outcome were calculated for ripples combined with PET,MEG,both PET and MEG,and PET combined with MEG.Kaplan-Meier survival analyses were conducted in each group to estimate prognostic value.Results:The study included 13 men and 8 women.Accuracy for ripples,PET,and MEG alone in predicting surgical outcome was 42.9%,42.9%,and 81.8%,respectively.Accuracy for ripples combined with PET and MEG was the highest.Resection of regions identified by ripples,MEG dipoles,and combined PET findings was significantly associated with better surgical outcome(P<0.05).Conclusions:Intracranial electrodes are essential to detect regions which generate ripples and to remove these areas which indicate good surgical outcome for medically intractable epilepsy.With the assistance of presurgical noninvasive imaging examinations,PET and MEG,for example,the SEEG electrodes would identify epileptogenic regions more effectively.

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.

Expert consensus on clinical applications of high-frequency oscillations in epilepsy

Studies in animal models of epilepsy and pre-surgical patients have unanimously found a strong correlation between high-frequency oscillations(HFOs,>80 Hz)and the epileptogenic zone,suggesting that HFOs can be a potential biomarker of epileptogenicity and epileptogenesis.This consensus includes the definition and standard detection techniques of HFOs,the localizing value of pathological HFOs for epileptic foci,and different ways to distinguish physiological from epileptic HFOs.The latest clinical applications of HFOs in epilepsy and the related findings are also discussed.HFOs will advance our understanding of the pathophysiology of epilepsy.

High-frequency oscillations detected by electroencephalography as biomarkers to evaluate treatment outcome,mirror pathological severity and predict susceptibility to epilepsy

High-frequency oscillations(HFOs)in the electroencephalography(EEG)have been extensively investigated as a potential biomarker of epileptogenic zones.The understanding of the role of HFOs in epilepsy has been advanced considerably over the past decade,and the use of scalp EEG facilitates recordings of HFOs.HFOs were initially applied in large scale in epilepsy surgery and are now being utilized in other applications.In this review,we summarize applications of HFOs in 3 subtopics:(1)HFOs as biomarkers to evaluate epilepsy treatment outcome;(2)HFOs as biomarkers to measure seizure propensity;(3)HFOs as biomarkers to reflect the pathological severity of epilepsy.Nevertheless,knowledge regarding the above clinical applications of HFOs remains limited at present.Further validation through prospective studies is required for its reliable application in the clinical management of individual epileptic patients.

CFD simulation of pumping ventilation in a three-story isolated building with internal partitioning:Effects of partition widths,heights and locations

Pumping ventilation(PV),a special single-sided ventilation(SSV),has been certified as an effective strategy to improve the air exchange rate of SSV.However,most studies targeted on the single space,and few studies have been focused on the effect of internal partitioning on PV.This paper aims to evaluate the ventilation performance of PV influenced by different configurations of internal partitioning.Computational fluid dynamics(CFD)simulation was used to predict the flow fields and ventilation rates.The width(w/H),height(h/H)and location(d/H)are the three main internal partition parameters considered in this study.The simulation results showed that the total,mean and fluctuating ventilation rates all decrease with wider internal partitions.The normalized total ventilation rate decreases by 7.6%when w/H is increased from 50%to 75%.However,the reduction rate is only 0.23%between w/H=0 and 25%,and only 0.61%between w/H=25%and 50%.The ventilation rate is hardly reduced by increasing the partition width when w/H<50%,whereas greatly reduced by wider partition for w/H>50%.Increasing the partition height will reduce the mean ventilation rate but promote the fluctuating and total ventilation rate in some cases.An increase of total ventilation rate by 1.4%is observed from h/H=50%to 75%.The ventilation rate is larger when the internal partition is attached to the leeward or windward wall.The total,mean and fluctuating ventilation rates for d/H=50%are relatively higher than d/H=0 by 1.5%,3.1%and 0.8%,respectively.Hence the internal partition should be mounted attached to the windward wall so as to obtain the greatest pumping ventilation rate.The periodicity of pumping flow oscillation and pumping frequency are independent of the partition configurations.The peak power of pumping flow is the lowest for the widest internal partition and is negatively affected by the partition height,but it generally has a positive correlation with the distance between the partition and leeward wall.Present research will help to understand pumping ventilation mechanism in real buildings with internal partitioning and provide theoretical basis for developing unsteady natural ventilation technology in low-carbon buildings.

猪肺磷脂注射液联合无创高频振荡通气对NRDS早产儿的影响

目的:探究猪肺磷脂注射液联合无创高频振荡通气(HFOV)对新生儿呼吸窘迫综合征(NRDS)早产儿肺表面活性蛋白A(SP-A)及肺循环功能的影响。方法:选取2022年3月—2024年2月江西省妇幼保健院新生儿科收治的120例NRDS早产儿,以随机数字表法分为对照组、观察组,各60例。在常规治疗基础上,对照组予以无创HFOV治疗,观察组予以猪肺磷脂注射液联合无创HFOV治疗。比较两组的疗效、治疗前后SP-A水平、肺循环功能指标[平均肺动脉压(MPAP)、肺血管阻力(PVR)、血管外肺水量(EVLW)]。结果:观察组总有效率高于对照组,差异有统计学意义(P<0.05)。治疗后,两组SP-A、MPAP、PVR、EVLW均低于治疗前,且观察组均低于对照组,差异均有统计学意义(P<0.05)。结论:猪肺磷脂注射液联合无创HFOV治疗NRDS早产儿,可提高疗效,降低患儿SP-A水平,改善肺循环功能,具有一定价值。

Experimental Analysis of Atypically Long Finned Oscillating Heat Pipe for Ventilation Waste Heat Recovery Application

Oscillating heat pipes(OHP)which are constructed from a serpentine-arranged capillary tube possess a desirable aerodynamic form factor and provide for relatively high heat transfer rates via cyclic evaporation and condensation of an encapsulated working fluid with no internal wicking structure required.In last two decades,OHP has been extensively investigated for its potential application in thermal management of various applications.This study presents an experimental investigation on the heat transfer performance of an atypically long finned OHP.The heat transfer performance of the proposed OHP was analyzed and compared with a bare tube OHP with similar overall dimensions.Results show that a unit row of finned OHP filled with n-pentane with fill ratio of 70%can recover up to(400±40)W of heat from a typical waste exhaust air stream.The additional pressure drop due to fins was estimated to be(6.8±2)Pa resulting in an increase of 1–2 W of fan power consumption.The average heat recovery rate via finned OHP was found to be almost 80%more than bare tube OHP filled with same working fluid with same fill ratio.

容量目标通气与高频振荡通气治疗新生儿呼吸窘迫综合征的效果比较

目的:对比研究容量目标通气、高频振荡通气两种模式在新生儿呼吸窘迫综合征中的治疗效果。方法:随机将2021年6月—2023年6月在湛江市妇幼保健计划生育服务中心治疗的新生儿呼吸窘迫综合征患儿100例分为对照组与研究组,每组50例。研究组采取高频振荡通气模式(高频机械通气+目标潮气量),对照组采取容量目标通气模式。对比两组动脉血气指标、并发症发生率、死亡率、有创通气时间、氧疗时间、住院时间。结果:研究组有创通气时间、氧疗时间、住院时间均短于对照组(P<0.05)。两组死亡率(0 vs 8.00%)比较,差异无统计学意义(P>0.05)。干预前两组血氧分压、血氧饱和度、pH值、二氧化碳分压比较,差异均无统计学意义(P>0.05);干预48 h后,研究组的血氧分压、血氧饱和度、pH值较干预前和对照组均更高,二氧化碳分压较干预前和对照组更低(P<0.05)。研究组的并发症发生率(10.00%)低于对照组(36.96%)(P<0.05)。结论:高频振荡通气模式可以更有效地改善新生儿呼吸窘迫综合征患儿动脉血气指标,缩短康复时间,减少各类并发症出现。

高频震荡通气治疗新生儿支气管肺发育不良的效果及对肺功能、血气分析的影响

目的:探究高频震荡通气治疗新生儿支气管肺发育不良的效果,以及对肺功能、血气分析的影响。方法:选择2020年6月—2023年3月大连市妇女儿童医疗中心(集团)春柳院区收治的97例支气管肺发育不良新生儿,根据随机数字表法分为对照组(n=48)和观察组(n=49)。对照组进行常规机械通气,观察组则进行高频震荡通气。比较两组的总有效率、吸氧时间、机械通气时间、并发症总发生率、治疗前后的肺功能指标[25%潮气容积时的呼气流量(TEF25)、50%潮气容积时的呼气流量(TEF50)、达峰时间比(TPTEF/TE)及达峰容积比(VPEF/VE)]及血气分析结果[动脉血氧分压(PaO_(2))及动脉血二氧化碳分压(PaCO_(2))]。结果:观察组总有效率显著高于对照组,吸氧时间及机械通气时间均短于对照组,并发症总发生率显著低于对照组(P<0.05)。治疗前,两组TEF25、TEF50、TPTEF/TE、VPEF/VE、PaO_(2)、PaCO_(2)比较,差异均无统计学意义(P>0.05);治疗2、7 d后,两组TEF25、TEF50、TPTEF/TE、VPEF/VE、PaO_(2)均高于治疗前,PaCO_(2)均低于治疗前,且观察组TEF25、TEF50、TPTEF/TE、VPEF/VE、PaO_(2)均高于对照组,PaCO_(2)均显著低于对照组(P<0.05)。结论:高频震荡通气在新生儿支气管肺发育不良中的应用效果较好,可显著改善患儿的肺功能及血气分析状态,在新生儿支气管发育不良中的应用价值较高。

振荡筛孔雾化在机械通气患者中的应用

目的分析机械通气患者的雾化给药中实施振荡筛孔雾化装置给药对于患者呼吸系统状态的影响。方法选取2020年9月至2022年12月赣南医学院附属兴国医院重症医学科实施机械通气支持的62例呼吸系统疾病患者作为研究对象,依据奇偶数法分为对照组和观察组,每组各31例。对照组实施常规氧气雾化给药,观察组实施振荡筛孔雾化给药。比较两组患者不同给药方案下呼吸参数、雾化指标、血气指标、血清炎症指标。结果观察组治疗后潮气量、动态顺应性均高于对照组,气道峰压、呼吸频率低于对照组,差异有统计学意义(P<0.05);观察组患者的雾化准备时间、雾化给药时间、雾化给药残余量短于对照组,雾化后呼吸机报警次数均低于对照组,差异有统计学意义(P<0.05);观察组患者治疗后的氧分压、氧合指数、酸碱度值高于对照组,二氧化碳分压、呼吸频率低于对照组,两组患者治疗后的氧分压、氧合指数、酸碱值高于治疗前,二氧化碳分压、呼吸频率低于治疗前,差异有统计学意义(P<0.05);观察组患者治疗后的白介素-13、降钙素原、人可溶性细胞间黏附分子、粒细胞-巨噬细胞集落刺激因子、C反应蛋白低于对照组,两组患者治疗后的炎症指标低于治疗前,差异有统计学意义(P<0.05)。结论机械通气患者的雾化给药中实施振荡筛孔雾化装置给药可提升给药效能,缩短给药时间,改善患者的呼吸指标,促进患者的炎症消退,具有重要应用价值。