Spatial-temporal variation features and law of gas concentration in the fully mechanized working face under the condition of intermittent ventilation

Based on the fluid mechanics and mass transfer theory,a mathematical model of the spatial-temporal variation of gas was derived to avoid the gas accident caused by the main fan stopping ventilation under the condition of intermittent ventilation in the tunnel.According to the actual parameters of the tunnel,a numerical calculation model was established.The spatial-temporal variation of gas concentration in the fully mechanized working face under the condition of intermittent ventilation was calculated by using the commercial package Fluent,and the correctness of the calculated results was verified by the actual monitoring data of the mine.Firstly,the gas concentration was calculated under different wind velocities at driving face in coal tunnel,and the result showed that the gas can be carried effectively by the wind when the wind velocity is about 1.8 m/s.Secondly,the distributions of wind velocity and gas concentration at driving face were studied at 1.8 m/s,and the result showed the gas concentration increased gradually with the distance close to the outlet,but the gas concentration almost kept constant at the height of driving face.Thirdly,the distribution of gas concentration was investigated with time after the ventilation was stopped and restarted,respectively.The gas concentration of test point gradually increased with the increment of downtime,when the downtime was 40 min,the gas concentration of test point 3 reached the maximum value.The gas concentration increased gradually and reached the maximum after10 min of restart,then sharply decreased and kept constant.

Clinical characteristics and outcomes associated with nasal intermittent mandatory ventilation in acute pediatric respiratory failure

AIM To characterize the clinical course and outcomes of nasal intermittent mandatory ventilation(NIMV) use in acute pediatric respiratory failure.METHODS We identified all patients treated with NIMV in the pediatric intensive care unit(PICU) or inpatient general pediatrics between January 2013 and December 2015 at two academic centers.Patients who utilized NIMV with other modes of noninvasive ventilation during the same admission were included.Data included demographics,vital signs on admission and prior to initiation of NIMV,pediatric risk of mortality Ⅲ(PRIsM-Ⅲ) scores,complications,respiratory support characteristics,PICU and hospital length of stays,duration of respiratory support,and complications.Patients who did not require escalation to mechanical ventilation were defined as NIMV responders;those who required escalation to mechanical ventilation(MV) were defined as NIMV nonresponders.NIMV responders were compared to NIMV non-responders.RESULTS Forty-two patients met study criteria.six(14%) failed treatment and required MV.The majority of the patients(74%) had a primary diagnosis of bronchiolitis.The median age of these 42 patients was 4 mo(range 0.5-28.1 mo,IQR 7,P = 0.69).No significant difference was measured in other baseline demographics and vitals on initiation of NIMV;these included age,temperature,respiratory rate,O2 saturation,heart rate,systolic blood pressure,diastolic blood pressure,and PRIsM-Ⅲ scores.The duration of NIMV was shorter in the NIMV nonresponder vs NIMV responder group(6.5 h vs 65 h,P < 0.0005).Otherwise,NIMV failure was not associated with significant differences in PICU length of stay(LOs),hospital LOs,or total duration of respiratory support.No patients had aspiration pneumonia,pneumothorax,or skin breakdown.CONCLUSION Most of our patients responded to NIMV.NIMV failure is not associated with differences in hospital LOs,PICU LOs,or duration of respiratory support.

Effect of the adaptive intermittent ventilation before radical operation for lung cancer under one-lung ventilation on the non-ventilated lung tissue injury and apoptosis molecule protein expression

Objective: To study the effect of the adaptive intermittent ventilation before radical operation for lung cancer under one-lung ventilation on non-ventilated lung tissue injury and apoptosis molecule protein expression. Methods: A total of 288 patients who received radical operation for lung cancer in the hospital between February 2015 and January 2017 were divided into control group and observation group by random number table method, each with 144 cases. Control group received routine one-lung ventilation, and observation group received preoperative adaptive intermittent ventilation of non-ventilated lung tissue. The differences in the levels of inflammatory factors and oxidative stress indexes in serum as well as the apoptosis molecule protein expression in affected-side normal lung tissue were compared between the two groups of patients immediately after intubation and at two-lung ventilation (T0) as well as 10 min before operation ended and at one-lung ventilation (T1). Results: At T0, the differences in the levels of inflammatory factors and oxidative stress indexes in serum as well as the apoptosis molecule protein expression in affected-side normal lung tissue were not significantly significant between the two groups of patients;at T1, IL-1β, IL-8, TNF-α, MPO and MDA levels in serum as well as Bax, caspase-2 and caspase-3 protein expression in normal lung tissue of observation group were lower than those of control group while SOD level in serum and Bcl-2 protein expression in normal lung tissue were higher than those of control group. Conclusion: Adaptive intermittent ventilation before radical operation for lung cancer under one-lung ventilation can effectively reduce the non-ventilated lung tissue injury and inhibit the apoptosis of normal lung cells.

Building cooling by night-time ventilation

Nowadays,the world is short of energy source,and larger proportion of building energy consumption is occupied by air conditioning system. It is urgent that not only importance should be attached on energy saving but also arcology energy technology based on green and sustainable thought should be advocated. Considering the ever growing energy consumption of residential buildings,intermittent ventilation is a solution to saving energy consumption and improving indoor thermal comfort. Aiming at reducing indoor air temperature by intermittent ventilation and decrease energy consumption of air conditioning system,with the help of DeST (Designer's Simulation Toolkit) this paper analyzes the characteristics of air conditioning load and year round air conditioning time in Chongqing located in hot summer and cold winter zone,obtains the amount of energy consumption saved at different ventilation rates,and recommends suitable ventilation rate in hot summer and cold winter zone.

Influence of Leakage from Non-Invasive Positive Pressure Ventilation Mask on FiO₂Value Delivered by Home Oxygen Therapy Concentrator: A Bench Study on Simulating Patients with Chronic Obstructive Pulmonary Disease

Introduction: During the application of non-invasive positive pressure ventilation (NPPV) therapy in home mechanical ventilation (HMV), leaks in the NPPV mask may occur owing to the position of the mask due to conditions such as skin disorders. Methods: To investigate whether such a leak affects FiO2 supplied to the alveoli, we simulated a patient with chronic obstructive pulmonary disorder during NPPV in HMV. In addition, FiO2 was measured in the portion assumed to be the mouth and lungs while setting the flow of the oxygen concentrator and leak amount based on a previous study. Results: FiO2 supplied to the lungs increased statistically significantly upon increasing the amount of leak (P Conclusions: We observed that FiO2 supplied to alveoli can be reduced by a leak in the NPPV mask. Because our results differ from those previously reported, we believe that further studies should reassess the selection of respirators and oxygen concentrators.

Non-Invasive Pressure Support Ventilation in Major Lung Resection for High Risk Patients: Does It Matter?

Background and purpose: Patients with severely impaired pulmonary function have an increased operative risk for major lung resection. The clinical benefits of pre- and perioperative, non-invasive pressure support ventilation (NIPSV) have up to now not been extensively evaluated. Patients with severely reduced pulmonary function were investigated in this prospective and randomised single centre clinical trial. Methods: Standard pulmonary evaluation was performed in all patients before major lung resection. To predict postoperative pulmonary function, a lung perfusion-ventilation scan was carried out. All patients enrolled in the study were instructed preoperatively on how to use a NIPSV respirator. Af-ter lung resection patients were randomised either for continuation of NIPSV or for standard treatment. Results: Of the 52 patients assessed, 21 patients met the inclusion criteria for the study protocol. Predicted mean postoperative FEV1 was 1.10 L (range 0.92 - 1.27 L). Lobectomy was performed in 14 patients, pneumonectomy in 6 patients and a segmentectomy in 1 patient. No inhospital deaths occurred. Pulmonary complications (reintubation, pneumonia) were more frequent in the NIPSV group than in the control group (3 patients versus 1 patient), without statistical significance (p = 0.31). Conclusions: We observed no mortality and a low morbidity in this high risk group. Postoperative continuation of NIPSV had no beneficial effect on the clinical outcome. Preoperative conditioning with NIPSV, however, seems to be a suitable tool for patients with severely impaired pulmonary function. This study may serve therefore as basis for further investigations for the potential clinical benefits of prophylactic NIPSV in major lung surgery.

Occupancy-aided ventilation for airborne infection risk control:Continuously or intermittently reduced occupancies?

Ventilation is an important engineering measure to control the airborne infection risk of acute respiratory diseases,e.g.,Corona Virus Disease 2019(COVID-19).Occupancy-aided ventilation methods can effectively improve the airborne infection risk control performance with a sacrifice of decreasing working productivity because of the reduced occupancy.This study evaluates the effectiveness of two occupancy-aided ventilation methods,i.e.,the continuously reduced occupancy method and the intermittently reduced occupancy method.The continuously reduced occupancy method is determined by the steady equation of the mass conservation law of the indoor contaminant,and the intermittently reduced occupancy method is determined by a genetic algorithm-based optimization.A two-scenarios-based evaluation framework is developed,i.e.,one with targeted airborne infection risk control performance(indicated by the mean rebreathed fraction)and the other with targeted working productivity(indicated by the accumulated occupancy).The results show that the improvement in the airborne infection risk control performance linearly and quadratically increases with the reduction in the working productivity for the continuously reduced occupancy method and the intermittently reduced occupancy method respectively.At a given targeted airborne infection risk control performance,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the working productivity by up to 92%.At a given targeted working productivity,the intermittently reduced occupancy method outperforms the continuously reduced occupancy method by improving the airborne infection risk control performance by up to 38%.

无创通气间歇期经鼻高流量湿化氧疗治疗慢性阻塞性肺疾病急性加重临床效果及对患者气管插管率、血气指标的影响

目的:分析无创通气(NIV)间歇期经鼻高流量湿化氧疗(HFNC)治疗慢性阻塞性肺疾病急性加重(AECOPD)临床效果及对气管插管率、血气指标的影响。方法:回顾性收治的105例AECOPD患者资料,将患者分为对照组52例[接受无创通气(NIV)治疗与常规氧疗]和观察组53例(接受NIV联合HFNC治疗),比较两组患者临床指标、血气指标、治疗失败原因及不良反应。结果:观察组呼吸支持时间、NIV间歇歇息次数、NIV每日平均使用时间、ICU住院时间均短(小)于对照组(均P<0.05),两组气管插管率比较差异无统计学意义(P>0.05);治疗后两组动脉血氧分压(PaO_(2))比治疗前明显升高,动脉血二氧化碳分压(PaCO_(2))比治疗前明显降低(P<0.05),但两组治疗后PaO_(2)、PaCO_(2)水平比较差异无统计学意义(均P>0.05);观察组患者呼吸困难加重率、治疗不耐受率均低于对照组(均P<0.05),两组CO_(2)潴留加重率、低氧血症加重率比较差异无统计学意义(均P>0.05);观察组不良反应发生率显著低于对照组(P<0.05)。结论:NIV间歇期给予HFNC治疗AECOPD患者对气管插管率及血气指标的影响与常规氧疗差异不显著,但可改善患者其他临床指标,减少治疗失败情况及不良反应。

基于循证理论的预见性护理策略结合声门下间歇冲洗预防2型糖尿病伴心力衰竭患者呼吸机相关性肺炎的效果及对炎性介质水平的影响

目的分析基于循证理论的预见性护理策略结合声门下间歇冲洗在预防2型糖尿病(T2DM)伴心力衰竭(HF)患者呼吸机相关性肺炎(VAP)中的应用效果。方法择取2021年1月至2022年1月收治的100例T2DM伴HF患者为研究对象,随机将其分为对照组和观察组,各50例。对照组采用常规护理干预,观察组在对照组基础上加基于循证理论的预见性护理策略结合声门下间歇冲洗。比较两组的干预效果。结果观察组的VAP发生率、随机血糖水平低于对照组,机械通气时间、气管插管时间及住院时间短于对照组(P<0.05)。干预后,观察组的肿瘤坏死因子-α(TNF-α)、降钙素原(PCT)及C反应蛋白(CRP)水平低于对照组(P<0.05)。干预后,观察组的脑钠肽(BNP)水平及糖化血红蛋白(HbA1c)低于对照组(P<0.05)。结论基于循证理论的预见性护理策略结合声门下间歇冲洗能够有效预防T2DM伴HF患者VAP的发生,降低炎性介质水平,改善血糖及心功能,值得临床推广与应用。

不同无创通气联合枸橼酸咖啡因治疗早产儿呼吸暂停疗效分析

目的通过分析不同无创辅助通气模式联合枸橼酸咖啡因在早产儿呼吸暂停中的治疗效果,探讨治疗早产儿呼吸暂停的优化方案。方法选择2019年10月~2022年8月蚌埠医学院第二附属医院新生儿重症监护病房收治的90例胎龄≤34周的呼吸暂停患儿作为研究对象,回顾性分析患儿的病例资料,将患儿分为NCPAP联合枸橼酸咖啡因组(n=44)和NIPPV序贯NCPAP联合枸橼酸咖啡因组(n=46)。采用t检验、χ2检验、Mann-Whitney检验等,对两组患儿一般临床资料、呼吸暂停疗效、治疗时间及不良反应发生情况,进行统计学比较。结果NIPPV序贯NCPAP联合枸橼酸咖啡因组治疗早产儿呼吸暂停总有效率为91.30%,高于NCPAP联合枸橼酸咖啡因组的86.36%,差异有统计学意义(P<0.05);两组无创通气失败及相关治疗时间比较,差异有统计学意义(P<0.05);两组在喂养不耐受、鼻损伤发生情况比较,差异有统计学意义(P<0.05)。结论早期采用NIPPV序贯NCPAP的通气模式,较传统单用NCPAP治疗早产儿呼吸暂停,可以取得更好的临床效果,缩短治疗及住院时间,不良反应相对更少,值得临床推广。

新生儿呼吸窘迫综合征经鼻间歇正压通气治疗中的全面性护理效果

目的分析新生儿呼吸窘迫综合征经鼻间歇正压通气治疗中的全面性护理的效果。方法便利选择2020年1月—2023年3月邳州市中医院收治的55例新生儿呼吸窘迫综合征患儿为研究对象,经随机数表法分为两组,均行经鼻间歇正压通气治疗,对照组(27例)采取常规护理,观察组(28例)采取全面性护理。对比两组疼痛程度、血气指标、并发症发生情况。结果护理后,观察组疼痛评分为(3.24±0.72)分,低于对照组的(3.89±0.81)分,差异有统计学意义(t=3.148,P<0.05)。观察组的血氧饱和度、动脉血氧分压、氧合指数均高于对照组,差异有统计学意义(P均<0.05)。观察组的并发症发生率低于对照组(3.57%vs 25.93%),差异有统计学意义(χ^(2)=3.874,P<0.05)。结论予以新生儿呼吸窘迫综合征行经鼻间歇正压通气治疗和全面性护理可改善患儿血气指标,减轻患儿疼痛感,减少并发症发生率。

基于PMV的多区域暖通空调事件触发间歇控制研究

提高建筑能源管理效率一直是研究的热点问题,尤其是暖通空调(HVAC)作为主要的能源消耗者.本研究针对多区域HVAC系统,提出了一种基于预测平均感觉值(PMV)的事件触发间歇控制策略,旨在提升建筑的能源管理效率及室内热舒适度.将PMV指数范围作为事件触发间歇控制的规则,设计了相应的间歇控制器,可以得到多区域HVAC系统室内温度维持在可接受范围内的可行条件,同时排除了Zeno行为;通过数值仿真与连续控制策略的对比分析,证实了该控制策略在提供良好热舒适性的同时,具有显著的节能优势.

NIPPV联合LISA技术治疗NRDS效果及对早产儿动脉血气、不良事件发生的影响

目的:探究经鼻间歇正压通气(NIPPV)联合微创注入肺表面活性物质治疗(LISA)技术治疗新生儿呼吸窘迫综合征(NRDS)效果及对早产儿动脉血气、不良事件发生率的影响分析。方法:选取2020年6月-2023年9月本院诊治的96例NRDS早产儿,简单随机分组法分为观察组和对照组各48例,两组均在新生儿重症监护病房实施无创辅助通气治疗,其中对照组行经鼻持续气道正压通气(NCPAP)+LISA技术治疗,观察组行NIPPV+LISA技术治疗,比较两组临床治疗情况、动脉血气指标[动脉血氧分压(PaO_(2))、动脉血二氧化碳分压(PaCO_(2))、动脉血氧饱和度(SiO_(2))、PH]、指标、肺氧合指标[动脉血氧分压/肺泡氧分压(PaO_(2)/PAO_(2))、氧合指数(OI)]及不良事件发生率。结果:治疗后,观察组无创通气时间(5.3±1.7d)、有创通气占比(16.7%)、总氧疗时间(10.7±2.2d)、住院时间(27.9±4.3d)均低于对照组(6.6±2.0d、35.4%、12.4±2.5d、31.6±5.1d),撤机成功占比(87.5%)高于对照组(72.9%);两组PaO_(2)、SiO_(2)、PaO_(2)/PAO_(2)、PH值均升高,PaCO_(2)、OI水平均降低,且观察组改善幅度大于对照组;观察组总不良事件发生率(8.3%)低于对照组(25.0%)(均P<0.05)。结论:NIPPV联合LISA技术可更有效改善NRDS早产儿动脉血气,增强肺通气,促进临床症状改善,缩短住院时间。

对呼吸窘迫综合征早产儿进行经鼻间歇正压通气治疗的疗效分析

目的评估呼吸窘迫综合征(Respiratory Distress Syndrome,RDS)早产儿接受经鼻间歇正压通气(Nasal Intermittent Positive Pressure Ventilation,NIPPV)治疗的效果。方法回顾性选取桓台县妇幼保健院于2020年9月—2022年9月收治的71例RDS早产儿的临床资料,参照治疗方法划分对照组[纳入36例,给予经鼻持续气道正压通气(Nasal Continuous Positive Airway Pressure,NCPAP)]和观察组(纳入35例,给予NIPPV),比较两组血二氧化碳分压(Arterial Carbon Dioxide Pressure,PaCO_(2))、动脉血氧分压(Arterial Partial Oxygen Pressure,PaO_(2))、酸碱度(Pondus Hydrogenii,pH)、治疗情况、并发症发生率。结果治疗后,观察组PaCO_(2)低于对照组,PaO_(2)、pH高于对照组,差异有统计学意义(P均<0.05)。观察组氧疗时间为(73.53±6.71)h,短于对照组的(84.35±7.73)h,差异有统计学意义(t=6.291,P<0.05)。观察组有创通气率、PS使用率低于对照组,差异有统计学意义(P均<0.05)。观察组并发症发生率为5.71%,低于对照组的25.00%,差异有统计学意义(P<0.05)。结论对RDS早产儿实施NIPPV,可以改善血气分析结果,降低有创通气率、PS使用率,减少并发症,缩短氧疗时间。

不同机械通气模式治疗呼吸衰竭新生儿的疗效及安全性分析

目的 探究治疗新生儿呼吸衰竭时,使用不同机械通气方式的临床效果以及安全性。方法 选取2018年3月—2022年3月在本院治疗的380例呼吸衰竭新生儿为研究对象,以随机选择法分为对照组和观察组,对照组使用持续气道正压通气模式,观察组使用同步间歇指令通气模式,对比两组并发症情况、临床住院时间,呼吸机通气时间等指标以及血气指标。结果 与对照组相比较,观察组临床住院时间、通气时间更短,且不良事件发生率较低,差异具有统计学意义(P<0.05);治疗后,观察组呼吸、氧化指数等指标显著较低,血氧分压氧化指数数值较高,差异具有统计学意义(P<0.05)。结论 在治疗呼吸衰竭新生儿过程中,相较于持续气道正压,通气模式使用同步间歇指令通气模式,可帮助患儿恢复血气指标,缩短呼吸机使用时间及临床治疗时间,降低机械通气治疗后不良事件发生率,促进其肺部功能恢复,治疗效果较为确切。

Unexpected complication during extracorporeal membrane oxygenation support: Ventilator associated systemic air embolism

Systemic air embolism through a bronchovenous fistu-la(BVF) has been described in patients undergoing positive-pressure ventilation. However, no report has mentioned the potential risks of systemic air embolism through a BVF in patients undergoing extracorporeal membrane oxygenation(ECMO). Positive-pressure ventilation and ECMO support in patients with lung injury can increase the risk of systemic air embolism through a BVF. Increased alveolar pressure, decreased pulmonary venous pressure, and anticoagulation are thought to be the factors that contribute to this complication. Here, we present a case of systemic air embolism in a patient with ECMO and mechanical ventilator support.

Localization and characterization of intermittent pollutant source in buildings with ventilation systems:Development and validation of an inverse model

Terrorist attacks through building ventilation systems are becoming an increasing concern.In case pollutants are intentionally released in a building with mechanical ventilation systems,it is critical to localize the source and characterize its releasing curve.Previous inverse modeling studies have adopted the adjoint probability method to identify the source location and used the Tikhonov regularization method to determine the source releasing profile,but the selection of the prediction model and determination of the regularization parameter remain challenging.These limitations can affect the identification accuracy and prolong the computational time required.To address the difficulties in solving the inverse problems,this work proposed a Markov-chain-oriented inverse approach to identify the temporal release rate and location of a pollutant source in buildings with ventilation systems and validated it in an experimental chamber.In the modified Markov chain,the source term was discrete by each time step,and the pollutant distribution was directly calculated with no iterations.The forward Markov chain was reversed to characterize the intermittently releasing profile by introducing the Tikhonov regularization method,while the regularized parameter was determined by an automatic iterative discrepancy method.The source location was further estimated by adopting the Bayes inference.With chamber experiments,the effectiveness of the proposed inverse model was validated,and the impact of the sensor performance,quantity and placement,as well as pollutant releasing curves on the identification accuracy of the source intensity was explicitly discussed.Results showed that the inverse model can identify the intermittent releasing rate efficiently and promptly,and the identification error for pollutant releasing curves with complex waveforms is about 20%.

不同无创呼吸机支持模式治疗新生儿呼吸窘迫综合征的临床效果

目的:探究无创间歇正压通气(NIPPV)和经鼻持续气道正压通气(NCPAP)两种无创呼吸机支持模式治疗新生儿呼吸窘迫综合征(NRDS)的临床疗效及并发症发生情况。方法:回顾性分析2020年6月~2022年2月安徽医科大学附属安庆第一人民医院收治的60例NRDS患儿作为研究对象。根据接受的无创呼吸机支持模式的不同,分为对照组(NCPAP模式)和研究组(NIPPV模式),每组30例。分析两组患儿治疗前、后动脉血氧分压(PaO_(2))、二氧化碳分压(PaCO_(2))、pH变化。比较两组新生儿的给氧时间、机械通气时间、住院时间。对两组新生儿支气管肺发育不良(BPD)、气胸、胃肠功能障碍、坏死性小肠结膜炎(NEC)、肺部感染、视网膜病变等并发症的发生情况进行比较,评估两种不同无创呼吸机支持模式的临床疗效。结果:与治疗前相比,两组新生儿治疗后PaO_(2)、pH均升高(P<0.05),PaCO_(2)降低(P<0.05);研究组治疗期间PaO_(2)、pH上升和PaCO_(2)值下降幅度均优于对照组(P<0.05)。研究组给氧时间、机械通气时间、住院时间均短于对照组(P<0.05)。两组新生儿BPD、气胸、肺部感染、胃肠功能紊乱发生率差异均无统计学意义(P>0.05),且两组均无NEC、视网膜病变发生。结论:NIPPV模式治疗NRDS,疗效明显优于NCPAP模式,NIPPV模式可有效改善NRDS患儿肺功能与血氧状态,缩短无创呼吸机支持时间及住院时间,值得临床推广应用。