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 ...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.展开更多
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 ...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.展开更多
A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply...A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply grille shape and room height on the jet flow behavior as well as the draught discomfort are analyzed for IJV operating in heating scenarios.The results indicate that the warm supply jet of IJV rises upward to the ceiling after spreading along the floor for a certain distance due to thermal buoyancy,resulting in a limited dispersion area,while the cool and isothermal jets of IJV always spread along the whole floor.When IJV is used for space heating,the lower the jet discharge height,the farther the supply air spreads along the floor,and the supply grille shape and room height almost have no effect on the air dispersion area.The results also show that the energy-efficient advantage of IJV in its heating mode compared to the mixing ventilation(MV)system is more remarkable in higher rooms.Moreover,there is a risk of draught discomfort in IJV heating rooms and it is recommended to wear socks to avoid this discomfort.展开更多
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 distributio...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.展开更多
Stratified air distribution(STRAD)systems have been intensively investigated in recent decades for their energy-saving potential and good indoor air quality performance.However,the evaluation indices used to optimize ...Stratified air distribution(STRAD)systems have been intensively investigated in recent decades for their energy-saving potential and good indoor air quality performance.However,the evaluation indices used to optimize STRAD systems and the normalization methods for weight calculation vary from one research to another.This study aims to investigate the impacts of evaluation indices on the optimal return vent height of a room cooled by an impinging jet ventilation system(one type of STRAD system).The effects of several widely used normalization methods(i.e.,vector normalization,sum normalization,min-max normalization,and no normalization)on indices weights are investigated.The evaluation indices are cooling coil load(Q_(coil)),energy-saving potential(ΔQ_(coil)),mean age of air(MAA),CO_(2) mass fraction,temperature difference between the head and ankles(ΔT_(0.1-1.1)),predicted mean vote(PMV),predicted percentage of dissatisfied(PPD),and draft rate(DR).The multi-criteria optimization method is the entropy-based technique for order preference by similarity to ideal solution(E-TOPSIS).As a result,the min-max normalization method evens the weight of each index and results in unreasonable relative weights.Consequently,the raw matrix(i.e.,the normalization is omitted)is suggested for weight calculation.Among these indices,ΔT_(0.1-1.1) and PPD play critical roles.WithoutΔT_(0.1-1.1),the optimal return vent height changes from mid-level to near-floor,while without PPD,it changes to near-ceiling.Another important result is that the Q_(coil) plays the most trivial role,followed by MAA and DR.Therefore,the optimal return vent height is not determined by energy-saving performance but by performances of thermal comfort.展开更多
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 positi...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.展开更多
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...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.展开更多
Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In th...Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation performance.Comparative experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling efficiency.Due to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling effect.The proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort time.The results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.展开更多
文摘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.
基金National Natural Science Foundation of China(No.51278094)the Innovation Foundation of Shanghai Education Commission,China(No.13ZZ054)
文摘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.
基金supported by the National Natural Science Foundation of China(No.51278094 and No.51478098)the Innovation Foundation of Shanghai Education Commission(No.13ZZ054)the Natural Science Foundation of Jiangsu Province,China(No.BK20161336).
文摘A validated CFD model is employed to predict the airflow behavior in an impinging jet ventilation(IJV)room with cool,isothermal or warm jets.By using the numerical results,the influences of jet discharge height,supply grille shape and room height on the jet flow behavior as well as the draught discomfort are analyzed for IJV operating in heating scenarios.The results indicate that the warm supply jet of IJV rises upward to the ceiling after spreading along the floor for a certain distance due to thermal buoyancy,resulting in a limited dispersion area,while the cool and isothermal jets of IJV always spread along the whole floor.When IJV is used for space heating,the lower the jet discharge height,the farther the supply air spreads along the floor,and the supply grille shape and room height almost have no effect on the air dispersion area.The results also show that the energy-efficient advantage of IJV in its heating mode compared to the mixing ventilation(MV)system is more remarkable in higher rooms.Moreover,there is a risk of draught discomfort in IJV heating rooms and it is recommended to wear socks to avoid this discomfort.
基金supported by the National Natural Science Foundation of China(52178092)the Basic Research Funds for the Central Government"Innovative Team of Zhejiang University"under contract number(2022FZZX01-09).
文摘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.
基金This research is supported by Teaching Development Grant(PJ#6000738)Strategic Research Grant(PJ#7005679),City University of Hong Kong,Hong Kong SAR.The authors thank Dr.Kobayashi from Osaka City University for his kindly sharing of experimental data.
文摘Stratified air distribution(STRAD)systems have been intensively investigated in recent decades for their energy-saving potential and good indoor air quality performance.However,the evaluation indices used to optimize STRAD systems and the normalization methods for weight calculation vary from one research to another.This study aims to investigate the impacts of evaluation indices on the optimal return vent height of a room cooled by an impinging jet ventilation system(one type of STRAD system).The effects of several widely used normalization methods(i.e.,vector normalization,sum normalization,min-max normalization,and no normalization)on indices weights are investigated.The evaluation indices are cooling coil load(Q_(coil)),energy-saving potential(ΔQ_(coil)),mean age of air(MAA),CO_(2) mass fraction,temperature difference between the head and ankles(ΔT_(0.1-1.1)),predicted mean vote(PMV),predicted percentage of dissatisfied(PPD),and draft rate(DR).The multi-criteria optimization method is the entropy-based technique for order preference by similarity to ideal solution(E-TOPSIS).As a result,the min-max normalization method evens the weight of each index and results in unreasonable relative weights.Consequently,the raw matrix(i.e.,the normalization is omitted)is suggested for weight calculation.Among these indices,ΔT_(0.1-1.1) and PPD play critical roles.WithoutΔT_(0.1-1.1),the optimal return vent height changes from mid-level to near-floor,while without PPD,it changes to near-ceiling.Another important result is that the Q_(coil) plays the most trivial role,followed by MAA and DR.Therefore,the optimal return vent height is not determined by energy-saving performance but by performances of thermal comfort.
文摘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.
文摘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.
基金the financial support of the National Key Research and Development Program of China(Grant No.2018YFC0705306)National Natural Science Foundation of China(No.52108096)+1 种基金Fundamental Research Funds for the Central Universities(No.2682020CX28)project from Key Lab.of Marine Power Engineering and Tech.authorized by MOT(No.KLMPET2020-04)。
文摘Night ventilation is regarded as a promising cooling strategy by storing night cooling in the thermal mass of the building.However,night ventilation performance in hot summer is restricted by the climatic limits.In this paper,we propose a new solution as the integration of wall-attached night ventilation(WANV)and phase change material wallboard(PCMW).The principle of the proposed system is to utilize the wall-attached jet ventilation to achieve forced convection and to adopt latent energy storage of PCMW to enlarge the energy storage density capabilities,and the coupling method is expected to improve the night ventilation performance.Comparative experiments were conducted to evaluate the thermal performance of the hybrid system by evaluating indoor temperature history,thermal comfort time and cooling efficiency.Due to the high thermal energy storage density capability of PCMW,it was found that the presence of PCMW has a negative influence on night cooling efficiency but still has a positive influence on the overall cooling effect.The proposed WANV combined with the PCMW system significantly increased the temperature decrease of room air and west wall inside surface during one hour's night ventilation by 94.97%and 67.74%,respectively,and reached an extension of 38.42%of indoor thermal comfort time.The results highlight the potential of WANV integration of PCMW to improve the thermal performance of night ventilation.
