Heat shocks caused by alloy melt and coat spraying are the main reason of die plastic deformation and early fracture. Based on theoretical analysis of heat shock phenomenon, two characteristic parameters of die damage...Heat shocks caused by alloy melt and coat spraying are the main reason of die plastic deformation and early fracture. Based on theoretical analysis of heat shock phenomenon, two characteristic parameters of die damage caused by heat shock were proposed, which are heat shock plastic deformation index (HSPI) and heat shock crack index (HSCI). The effect of heat shock on die plastic deformation and fracture behaviors was described quantitatively by these two parameters. HSPI represents approaching of heat shock stress to die yield stress. Plastic deformation will happen on a die if this index reaches 1. HSCI represents approaching of heat shock stress to die tensile strength. Die fracture will happen if this index reaches 1. According to theoretical analysis of heat transfer, theoretical models of HSPI and HSCI were established. It is found that, the smaller the interfacial thermal resistance (ITR) is, the higher the pouring temperature and die temperature are before heat shock, and the greater the HSPI and HSCI are, which can be fitted as exponential curves, linear and cubic curves.展开更多
Non-invasive clinical examination has well-recognized limitations in detecting compensated and uncompensated low flow states and their severity.This paper describes the principles of near-infrared absorption spectrosc...Non-invasive clinical examination has well-recognized limitations in detecting compensated and uncompensated low flow states and their severity.This paper describes the principles of near-infrared absorption spectroscopy(NIRS)and the basis for its proposed use in heart failure/cardiogenic and septic shock to assess global and regional tissue oxygenation.The vascular occlusion test is explained.Limitations of NIRS,current controversies,and what is necessary in the future to make this technology a part of the initial and ongoing assessment of a patient are also discussed.The ultimate goal of such techniques is to prevent miss-assessment and inadequate resuscitation of patients,two major factors in the development of multisystem organ failure and death.展开更多
Septic shock in children is associated with high mortality and morbidity. Its management is time-sensitive and must be aggressive and target oriented. The use of clinical assessment alone to differentiate between cold...Septic shock in children is associated with high mortality and morbidity. Its management is time-sensitive and must be aggressive and target oriented. The use of clinical assessment alone to differentiate between cold and warm shock and to select the appropriate inotropic and vasoactive medications is fraught with errors. Semiquantitative and quantitative assessment of the preload,contractility and afterload using non-invasive tools has been suggested,in conjunction with clinical and laboratory assessment,to direct shock management and select between vasopressors,vasodilators and inotropes or a combination of these drugs. This review aims to describe non-invasive tools to assess the hemodynamic status in septic shock including echocardiography,trans-thoracic/trans-esophageal Doppler and electrical cardiometry. As septic shock is a dynamic condition that changes markedly overtime,frequent or continuous measurement of the cardiac output(CO),systemic vascular resistance(SVR) and other hemodynamic parameters using the above-mentioned tools is essential to personalize the treatment and adapt it over time. The different combinations of blood pressure,CO and SVR serve as a pathophysiological framework to manage fl-uid therapy and titrate inotropic and vasoactive drugs. Near infrared spectroscopy is introduced as a noninvasive method to measure end organ perfusion and assess the response to treatment.展开更多
BACKGROUND: Near-infrared spectroscopy(NIRS) non-invasively monitors muscle tissue oxygen saturation(St O2). It may provide a continuous noninvasive measurement to identify occult hypoperfusion, guide resuscitation, a...BACKGROUND: Near-infrared spectroscopy(NIRS) non-invasively monitors muscle tissue oxygen saturation(St O2). It may provide a continuous noninvasive measurement to identify occult hypoperfusion, guide resuscitation, and predict the development of multiple organ dysfunction(MOD) after severe trauma. We evaluated the correlation between initial St O2 and the development of MOD in multi-trauma patients.METHODS: Patients presenting to our urban, academic, Level I Trauma Center/Emergency Department and meeting standardized trauma-team activation criteria were enrolled in this prospective trial. NIRS monitoring was initiated immediately on arrival with collection of St O2 at the thenar eminence and continued up to 24 hours for those admitted to the Trauma Intensive Care Unit(TICU). Standardized resuscitation laboratory measures and clinical evaluation tools were collected. The primary outcome was the association between initial St O2 and the development of MOD within the f irst 24 hours based on a MOD score of 6 or greater. Descriptive statistical analyses were performed; numeric means, multivariate regression and rank sum comparisons were utilized. Clinicians were blinded from the StO 2 values.RESULTS: Over a 14 month period, 78 patients were enrolled. Mean age was 40.9 years(SD 18.2), 84.4% were male, 76.9% had a blunt trauma mechanism and mean injury severity score(ISS) was 18.5(SD 12.9). Of the 78 patients, 26(33.3%) developed MOD within the first 24 hours. The MOD patients had mean initial St O2 values of 53.3(SD 10.3), signifi cantly lower than those of nonMOD patients 61.1(SD 10.0); P=0.002. The mean ISS among MOD patients was 29.9(SD 11.5), significantly higher than that of non-MODS patients, 12.1(SD 9.1)(P<0.0001). The mean shock index(SI) among MOD patients was 0.92(SD 0.28), also signifi cantly higher than that of non-MODS patients, 0.73(SD 0.19)(P=0.0007). Lactate values were not signifi cantly different between groups.CONCLUSION: Non-invasive, continuous St O2 near-infrared spectroscopy values during initial trauma resuscitation correlate with the later development of multiple organ dysfunction in this patient population.展开更多
基金Project(2009ZX04014-072) supported by National S & T Major Project of ChinaProject(Z09000400950901) supported by Beijing Municipal Science and Technology Development Program
文摘Heat shocks caused by alloy melt and coat spraying are the main reason of die plastic deformation and early fracture. Based on theoretical analysis of heat shock phenomenon, two characteristic parameters of die damage caused by heat shock were proposed, which are heat shock plastic deformation index (HSPI) and heat shock crack index (HSCI). The effect of heat shock on die plastic deformation and fracture behaviors was described quantitatively by these two parameters. HSPI represents approaching of heat shock stress to die yield stress. Plastic deformation will happen on a die if this index reaches 1. HSCI represents approaching of heat shock stress to die tensile strength. Die fracture will happen if this index reaches 1. According to theoretical analysis of heat transfer, theoretical models of HSPI and HSCI were established. It is found that, the smaller the interfacial thermal resistance (ITR) is, the higher the pouring temperature and die temperature are before heat shock, and the greater the HSPI and HSCI are, which can be fitted as exponential curves, linear and cubic curves.
基金Supported by Slovenian Research Agency,No.P3-0043
文摘Non-invasive clinical examination has well-recognized limitations in detecting compensated and uncompensated low flow states and their severity.This paper describes the principles of near-infrared absorption spectroscopy(NIRS)and the basis for its proposed use in heart failure/cardiogenic and septic shock to assess global and regional tissue oxygenation.The vascular occlusion test is explained.Limitations of NIRS,current controversies,and what is necessary in the future to make this technology a part of the initial and ongoing assessment of a patient are also discussed.The ultimate goal of such techniques is to prevent miss-assessment and inadequate resuscitation of patients,two major factors in the development of multisystem organ failure and death.
文摘Septic shock in children is associated with high mortality and morbidity. Its management is time-sensitive and must be aggressive and target oriented. The use of clinical assessment alone to differentiate between cold and warm shock and to select the appropriate inotropic and vasoactive medications is fraught with errors. Semiquantitative and quantitative assessment of the preload,contractility and afterload using non-invasive tools has been suggested,in conjunction with clinical and laboratory assessment,to direct shock management and select between vasopressors,vasodilators and inotropes or a combination of these drugs. This review aims to describe non-invasive tools to assess the hemodynamic status in septic shock including echocardiography,trans-thoracic/trans-esophageal Doppler and electrical cardiometry. As septic shock is a dynamic condition that changes markedly overtime,frequent or continuous measurement of the cardiac output(CO),systemic vascular resistance(SVR) and other hemodynamic parameters using the above-mentioned tools is essential to personalize the treatment and adapt it over time. The different combinations of blood pressure,CO and SVR serve as a pathophysiological framework to manage fl-uid therapy and titrate inotropic and vasoactive drugs. Near infrared spectroscopy is introduced as a noninvasive method to measure end organ perfusion and assess the response to treatment.
文摘BACKGROUND: Near-infrared spectroscopy(NIRS) non-invasively monitors muscle tissue oxygen saturation(St O2). It may provide a continuous noninvasive measurement to identify occult hypoperfusion, guide resuscitation, and predict the development of multiple organ dysfunction(MOD) after severe trauma. We evaluated the correlation between initial St O2 and the development of MOD in multi-trauma patients.METHODS: Patients presenting to our urban, academic, Level I Trauma Center/Emergency Department and meeting standardized trauma-team activation criteria were enrolled in this prospective trial. NIRS monitoring was initiated immediately on arrival with collection of St O2 at the thenar eminence and continued up to 24 hours for those admitted to the Trauma Intensive Care Unit(TICU). Standardized resuscitation laboratory measures and clinical evaluation tools were collected. The primary outcome was the association between initial St O2 and the development of MOD within the f irst 24 hours based on a MOD score of 6 or greater. Descriptive statistical analyses were performed; numeric means, multivariate regression and rank sum comparisons were utilized. Clinicians were blinded from the StO 2 values.RESULTS: Over a 14 month period, 78 patients were enrolled. Mean age was 40.9 years(SD 18.2), 84.4% were male, 76.9% had a blunt trauma mechanism and mean injury severity score(ISS) was 18.5(SD 12.9). Of the 78 patients, 26(33.3%) developed MOD within the first 24 hours. The MOD patients had mean initial St O2 values of 53.3(SD 10.3), signifi cantly lower than those of nonMOD patients 61.1(SD 10.0); P=0.002. The mean ISS among MOD patients was 29.9(SD 11.5), significantly higher than that of non-MODS patients, 12.1(SD 9.1)(P<0.0001). The mean shock index(SI) among MOD patients was 0.92(SD 0.28), also signifi cantly higher than that of non-MODS patients, 0.73(SD 0.19)(P=0.0007). Lactate values were not signifi cantly different between groups.CONCLUSION: Non-invasive, continuous St O2 near-infrared spectroscopy values during initial trauma resuscitation correlate with the later development of multiple organ dysfunction in this patient population.
