• Tuberculosis and Respiratory Diseases
• /
• 제46권5호
• /
• pp.645-653
• /
• 1999

연구배경 및 목적 : 급성 호흡 부전으로 인공 호흡 치료를 받는 환자들에서 인공 호흡기 적용 및 이탈 시에 혈역학적 변화에 의해 심근 허혈이 발생될 수 있으나, 이에 연관된 연구는 많지 않다. 본 연구는 급성 호흡 부전으로 인공 호흡 치료를 받는 환자들에서 혈역학적 변화가 가장 심하게 초래될 수 있는 치료 시작 시와 이탈 시에 발생하는 심근 허혈의 빈도 및 그 발생과 관련된 인자들을 알아보고자 하였다. 대상 및 방법 : 급성 호흡 부전으로 서울 중앙 병원 내과계 중환자실에 입원하여 인공 호흡 치료를 받은 73명, 95예(남 : 여=35 : 38, 연령=$62.8{\pm}17.3$)를 대상으로 전향적 연구를 실시하였다. 인종 호흡 치료 시작 (69예) 및 이탈 (26예) 시에 24시간 holter monitoring을, 인공 호흡 치료 기간 중 1회의 심초음파를 실시하였다. 이탈 측정치 26예 중에서 5예는 이탈 시만 측정되었다. 심근 허혈은 1.5mm이상의 upsloping ST depression이나 1.0mm 이상의 downsloping 혹은 horizontal ST depression으로 정의하였으며, 환자의 증증도의 지표는 APACHE III score를 사용하였다. 결 과 : 24시간 holter monitoring에서 심근 허혈이 나타난 경우는 총 12명 (12.6%)에서 관찰되었고, 인공 호흡 치료 시작 시 11명 (15.9%), 이탈 시 1명 (3.8%)으로 시작 시에 심근 허혈의 발생 빈도가 높았다(p=0.12). 심초음파상 좌심부전이 없었던 73예 중에서는 8예(10.9%), 있었던 22예 중 4예(18.2%)에서 심근 허혈이 관찰되어 좌심부전이 호흡 부전과 동반된 경우 심근 허혈이 증가하는 경향을 보였다. 기존 심전도상 심근 허혈이나 이전의 심근 경색이 의심되었던 경우는 총 20예 (21.1%)로, 이중 2예 (10%)에서 심근 허혈이 관찰되어 유의한 상관 관계는 없었다. 인공 환기 시작이나 이탈 시 저산소증이나 과탄산혈증 및 전해질 이상의 유무, 혈중 CK-MB level, APACHE III score, shock의 유무, 패혈증의 유무, 인공 환기 양식, inotropics의 사용 여부 등은 심근 허혈의 발생과 유의한 상관 관계를 보이지 않았다. 검사 중의 최대 심박수와 최저 평균 혈압용 심근 허혈이 없었던 군에서 $129.5{\pm}29.7bpm$, $83.8{\pm}17.6mmHg$, 심근 허혈이 있었던 군에서 $137.2{\pm}30.9bpm$, $82.5{\pm}15.9mmHg$로 유의한 차이는 없었다. 결 론 : 급성 호흡 부전으로 인공 호흡 치료를 받는 환자들 중 심근 허혈은 12.6%에서 관찰되었으며 주로 인공 환기 시작 시에 관찰되었고, 좌심부전이나 심전도 이상의 유무와는 유의한 상관 관계를 보이지 않았다.

• Tuberculosis and Respiratory Diseases
• /
• 제52권1호
• /
• pp.14-23
• /
• 2002

배 경 : 부분액체환기 (partial liquid ventilation; PLV) 시 최적의 기계환기의 설정에 대해서는 아직 논란이 많은 상태이다. 이에 정상 폐의 PLV 시 가스교환에 영향을 주는 인자들을 관찰함으로써, PLV 시 최적의 기계환기 설정을 확립하는 데에 이용하고자 본 연구를 시행하였다. 방 법 : New Zealand 산 백색 토끼 7 마리를 기계환기를 시행하였다. 기계환기는 압력 조절 양식으로 일회호흡량 ($V_T$) 8 mL/kg, PEEP 4 $cmH_2O$, 흡기대호기비 (I: E ratio) 1:2, 흡입산소분율 ($F_IO_2$) 0.75로 설정하였고, 호흡수(RR)는 $PaCO_2$가 35~45 mmHg 사이에 유지되도록 조절하였다. 이후 30분마다 기계환기기의 설정을 protocol에 따라 변화시키면서 가스환기(gas ventilation; GV)를 시행하였는데 ; (1) 기저 설정 단계, (2) 역비환기 (inverse I: E ratio) 단계로 I:E ratio 2:1, (3) 고 PEEP 단계로 2단계와 같은 평균흡기압 (MIP)을 유지하는 정도의 PEEP 증가, (4) 고 $V_T$ 단계로 $V_T$ 15 mL/kg, (5) 고RR 단계로 4단계와 같은 분당환기량 (MV)을 유지하는 정도로 RR을 증가시켰다. 그 후 perfluorodecalin 18 mL/kg 주입 후 상기 protocol과 동일하게 PLV를 하였다. 각각에서 동맥혈가스검사와 폐역학 및 혈역학적 지표를 측정하였다. 결 과 : (1) GV 시 $PaO_2$는 다섯 단계를 거치는 동안 의미 있는 변화를 보이지 않았다. $PaCO_2$는 고 $V_T$단계와 고 RR 단계에서 의미 있게 감소하였다(p<0.05). GV 시 폐역학 및 혈역학적 지표의 의미 있는 변화는 보이지 않았다. (2) PLV 군의 기저 $PaO_2$는 $312{\pm}113$ mmHg로 GV군의 $504{\pm}81$ mmHg 에 비해 의미 있게 낮았다(p=0.001). PLV 시 역비환기 단계나 고 RR 단계에서는 기저설정 단계와 비교하여 $PaO_2$의 의미 있는 차이가 관찰되지 않았으나, 고 PEEP 단계 ($452{\pm}38$ mmHg)와 고 $V_T$($461{\pm}53$ mmHg) 단계에서는 기저설정 단계보다 유의한 상승이 관찰되었다. (3) $PaCO_2$는 GV군과 PLV군 모두에서 고 $V_T$ 단계와 고 RR 단계에서 기저설정 단계보다 의미 있게 낮았다. PLV군의 기저설정 단계와 고 RR 단계의 $PaCO_2$는 GV 군보다 의미 있게 증가하였다(p<0.05). (4) PLV 시 폐역학 및 혈역학적 지표의 의미 있는 변화는 보이지 않았다 결 론 : 정상 폐에서 PLV 시 최적의 가스교환을 위해서는 적절한 PEEP과 $V_T$이 중용할 것으로 사료된다.

• 한국태양에너지학회 논문집
• /
• 제33권2호
• /
• pp.70-77
• /
• 2013

Recently the radiant panel heating and cooling system has been regarded as an alternative of low temperature heating and high temperature cooling by applying the renewable energy sources to the heating and cooling of buildings. Especially this system can be used as HVAC system alternatives in super high-rise buildings for energy saving and thermal comfort. Also it can be possible to reduce the plenum space because the minimum ventilation air will be supplied into the space. This study focused on the evaluation the basic characteristics of thermal output in prefabricated steel wall panel system for radiant heating and cooling. In order to evaluate the thermal output according to both various supply water temperatures and supply water flow rates, three-dimensional dynamic heat transfer analysis was performed. As results, for the heating mode, thermal output increased by 26% with the supply temperature increasing by $5^{\circ}C$. The surface temperature of panels range within $1{\sim}3^{\circ}C$. For the cooling mode, thermal output decreased by 18.2% with the supply temperature increasing by $2^{\circ}C$. The surface temperature of panels range within $0.5{\sim}1^{\circ}C$ and it was shown the even temperature distribution.

• Journal of Chest Surgery
• /
• 제57권1호
• /
• pp.36-43
• /
• 2024

Background: Coronavirus disease 2019 (COVID-19) can lead to acute respiratory failure, which frequently necessitates invasive mechanical ventilation and extracorporeal membrane oxygenation (ECMO). However, the limited availability of ECMO resources poses challenges to patient selection and associated decision-making. Consequently, this retrospective single-center study was undertaken to evaluate the characteristics and clinical outcomes of patients with COVID-19 receiving ECMO. Methods: Between March 2020 and July 2022, 65 patients with COVID-19 were treated with ECMO and were subsequently reviewed. Patient demographics, laboratory data, and clinical outcomes were examined, and statistical analyses were performed to identify risk factors associated with mortality. Results: Of the patients studied, 15 (23.1%) survived and were discharged from the hospital, while 50 (76.9%) died during their hospitalization. The survival group had a significantly lower median age, at 52 years (interquartile range [IQR], 47.5-61.5 years), compared to 64 years (IQR, 60.0-68.0 years) among mortality group (p=0.016). However, no significant differences were observed in other underlying conditions or in factors related to intervention timing. Multivariable analysis revealed that the requirement of a change in ECMO mode (odds ratio [OR], 366.77; 95% confidence interval [CI], 1.92-69911.92; p=0.0275) and the initiation of continuous renal replacement therapy (CRRT) (OR, 139.15; 95% CI, 1.95-9,910.14; p=0.0233) were independent predictors of mortality. Conclusion: Changes in ECMO mode and the initiation of CRRT during management were associated with mortality in patients with COVID-19 who were supported by ECMO. Patients exhibiting these factors require careful monitoring due to the potential for adverse outcomes.

• 한국입자에어로졸학회지
• /
• 제20권2호
• /
• pp.47-56
• /
• 2024

In this study, an empirical study was conducted to investigate the clean air delivery rate (CADR) and the proper particle cleaned air delivery per hour (PCH) of the air cleaning device installed in passenger car cabin. Changes in internal particle concentration were measured in the cabins of the pick-up type engine-driven car and the electric vehicle depending on cabin air filters, ventilation modes, and blower settings. In the tested cars, PM_2.5 collection efficiency of the HEPA filter was higher than that of the genuine filter. The PM_2.5 collection efficiency of each cabin air filter was measured to be similar regardless of the blower setting of the tested cars. This means that the higher the blower setting, the higher the CADR and the PCH. The infiltration rate varies depending on the air tightness of the car. The cabin was more contaminated with particles under driving. From the CADRs measured inside the passenger car cabin, the recirculation mode of HVAC system is a more effective for managing ultrafine particles than the fresh air mode. From a few assumptions, the proper PCH was derived about 0.8 times/min (48 times/h). From this result and several experiments, the proper operation setting of air cleaning device installed inside cars can be found out to control indoor air quality. Also, an appropriate operation settings of HVAC system can be found with considering cooling and heating conditions for thermal comfort in passenger car cabin.

• 한국지열·수열에너지학회논문집
• /
• 제10권3호
• /
• pp.17-23
• /
• 2014

One major breakthrough in the field of heating, ventilation and air conditioning has been the development of heat pumps. Heat pump systems offer economic alternatives for recovering heat from different sources for use in various industrial, commercial and residential applications. In recent years, the heat pump has been tipped to have a very good potential for hot water production. This paper investigated the performance of a vapor injection heat pump with the variation of sub-cooler capacity at heating mode. The heating capacity of the vapor injection heat pump slightly increased with an increment of sub-cooler capacity, while COP didn't increase continuously. The 20% capacity of sub-cooler comparing with system capacity could be used as a standard to select sub-cooler capacity.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.208-213
• /
• 2010

In this study CFD(Computational Fluid Dynamics) analysis of the steady fire-driven fuid flow for the performance test of ventilation at railway tunnel between Heuksok and Nodeul Station from Seoul Metro 9 is performed. There were fans with exhaust and intake modes and each was installed at the middle and both ends of the tunnel. For this test, the pool fire source of methyl alcohol with 1.5MW and smoke generators were installed between the middle of tunnel and Heuksok Station. In this test, the smoke behavior from natural convection was observed for 10 minutes from the ignition of pool fire and then fans with intake-modes at both sides of Heuksok effect of fan-on with intake mode located in the opposite side of the tunnel nearby Heuksok Station on fire-driven fluid flow is studied on when the boundary conditions of fan-on at the tunnel between Heuksok and Nodeul Station are the same as test. FLUENT, a commercial CFD code, is used for this analysis.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2004년도 Proceedings of 2004 Korea-Japan Joint Seminar on Particle Image Velocimetry
• /
• pp.125-134
• /
• 2004

The improvement of artificial respiration method has brought about the decrease in mortality of pulmonary diseases patients. Various respiratory curative methods, inclusive of HFOV (High Frequency Oscillatory Ventilation), have been developed for more effectual and less harmful management of acute respiratory failure. However, the mechanism of gas transfer and diffusion in a bronchiole has not yet been clarified in detail. As a first approach to the problem, we measured oscillatory flows in a Y-shaped micro-channels as bronchiole model by micro Particle Image Velocimetry(micro PIV). In order to establish the fundamental technique of PIV measurements on oscillatory air flow in a micro-channel, we used about 500-nm-diameter incense smoke particles, a diode laser, a high speed camera including an objective lens, and a HFOV, which is effective technique for medical care of pulmonary disease patients, especially, infants. The bronchiole model size is that parent tube is $500\{mu}m$ width and $500\{mu}m$ depth, and daughter tubes are $450\{mu}m$ width and $500\{mu}m$ depth. From this study made on the phenomenon of fluid in micro size bronchus branch of a lung, we succeeded to get time series velocity distribution in a micro scale bronchial mode. The experimental results of velocity distribution changing with time obtained by micro PIV can give fundamental knowledge on oscillatory airflow in micro-channel.

• 한국안전학회지
• /
• 제21권1호
• /
• pp.35-40
• /
• 2006

A study on fire phenomena in a subway transit mass station has been carried out as a part of disaster prevention plan at the subway station. The ventilation facilities installed in both the platform and the trackway are designed to convert into a smoke exhaust system in emergency situation, creating such an environment as necessary for evacuation. 3 dimensional Numerical Simulations based on the CFD are carried out using a simulation tool, Fire Dynamic Simulator. Additionally, four different vent modes are made and performances are compared with the original design mode and each other to find better operation of vents at both the platform and the trackway in case of fire. From the result, an vent operational characteristics under the condition of installed PSD is clarified for the effective smoke and heat removal from the platform area compared with non installed PSD.

• 교육시설 논문지
• /
• 제21권2호
• /
• pp.33-39
• /
• 2014

In the case of low-rise buildings in seismic performance evaluation, lateral force resistance of the pillars affects the seismic performance of the building. Evaluation of the seismic performance of the column is determined by the holding performance is evaluated by comparing the shear strength and bending strength it was destroyed bylow intensity. In case of the school building, in order to install the large windows for ventilation and lighting of the partition walls are located between the pillars. The case of the pillars of these, shear failure occurs in the event of an earthquake is often, in the seismic performance evaluation, partition wall and the wall of the shim is evaluated ignoring, pillar of the general pillars If you have to calculate the results of the seismic performance distorted that are destroyed by bending behavior can be evaluated as often. Results of the study, when assessed by distinguishing the effective length of the column, it was found that when a seismic load is applied, it is possible to accurately predict the failure mode, reliable results of seismic performance evaluation of the school building.