Diaphragm ultrasonography as an alternative to whole-body plethysmography in pulmonary function testing.

OBJECTIVE: Whole-body plethysmography is a common method of measuring pulmonary function. Although this technique provides a sensitive measure of pulmonary function, it can be problematic and unsuitable in some patients. The development of more accessible techniques would be beneficial. METHODS: A prospective study was performed to validate diaphragm ultrasonography as an alternative to whole-body plethysmography in patients referred for pulmonary function testing. Diaphragm movement and position were assessed by ultrasonography after standard pulmonary function testing using whole-body plethysmography. RESULTS: A wide range of lung function was observed. Standard lung volumes were as follows: total lung capacity, 5.57 +/- 1.31 L, residual volume, 2.27 +/- 0.56 L; and vital capacity, 3.30 +/- 0.98 L (mean +/- SD). The ratio of forced expiratory volume in 1 second to forced vital capacity was calculated as 0.69 +/- 0.08. Ultrasonography showed that mean diaphragm excursion values were 11.1 +/- 3.8 mm (2-dimensional), 14.7 +/- 4.1 mm during quiet breathing (M-mode), and 14.8 +/- 3.9 mm during a maximal sniff (M-mode). The velocity of diaphragm movement rose sharply during the sniff maneuver from 15.2 +/- 5.8 mm/s during quiet breathing to 104.0 +/- 33.4 mm/s. Static 2-dimensional measures of diaphragm position at the end of quiet inspiration or expiration correlated with standard measures of lung volume on plethysmography (eg, a correlation coefficient of 0.83 was obtained with end inspiration and vital capacity). All measures of diaphragm movement (whether by 2-dimensional or M-mode techniques) were poorly correlated with any lung volumes measured. CONCLUSIONS: These data suggest that dynamic measurements using diaphragm ultrasonography provide a relatively poor measure of pulmonary function in relation to whole-body plethysmography.     

Measurement of systolic time intervals during exercise using inductive plethysmography

Summary Measurement of systolic time intervals (STI) provides a noninvasive assessment of cardiac function in resting subjects. However, large motion artifacts often limit their application during exercise. To improve such measurements, we employed a new lightweight carotid arterial pulse transducer and minimized the artifacts by computerized signal averaging. The carotid pulse was recorded with an inductive plethysmographic transducer band (CIP) wrapped around the neck. STI derived from these measurements were compared to standard measurements from a funnel-shaped cup attached to the neck and connected to a pressure transducer (CUP) in 12 normal subjects at rest and with graded bicycle ergometry. To compare the techniques, CIP and CUP signals, together with the EKG and phonocardiogram, were connected separately to two microcomputer systems. The systems were triggered from the EKG and averaged the signals over 16 or 32 heart beats. Semi-automatic analysis of the averaged signals provided estimates of left ventricular ejection time (LVET), pre-ejection period (PEP) and electromechanical systole (QS₂). Motion artifact levels of the unprocessed signals were similar with both CIP and CUP methods but were greatly reduced by signal averaging. All LEVT values using CIP fell within 10% of CUP values. 85% of PEP values using CIP were within 20% of CUP values. Increasing exercise loads produced appropriate decreases in QS₂, LVET, PEP and PEP/LVET consistent with increased myocardial contractility. The CIP proved comfortable to wear and did not require critical positioning as did the CUP. Measurement of STI complements exercise pulmonary testing with useful information of cardiac function.     

An assessment of pulmonary function testing and ventilatory kinematics by optoelectronic plethysmography

New advances in computer processing and imaging have allowed the development of innovative techniques to assess lung function. A promising methodology is optoelectronic plethysmography (OEP). OEP evaluates ventilatory kinematics through the use of infrared imaging. Markers are placed, and images read on the chest, back and abdomen of subjects. Currently, this system is used mainly in research settings, but in the future may have broad applicability to patient populations such as very young children, patients with neuromuscular disease and patients who cannot be tested with classical spirometry testing. This paper presents the history and development of OEP, along with a summary of the OEP methodology, a discussion of research findings and results to date, as well as application and limitations.     

Reproducibility of air plethysmography for the evaluation of arterial and venous function of the lower leg

This study assessed the test-retest reliability of air plethysmographic parameters for the evaluation of arterial and venous function of the lower extremity in normal, healthy adults. Fourteen voluntary subjects underwent air plethysmographic tests on two occasions, 1-2 weeks apart, with three tests being performed at each visit. Test-retest reliability was assessed via correlation coefficients and the intraclass correlations. Differences in the parameters of arterial inflow (AI), venous volume (VV), venous refilling time (VFT), venous refilling index (VFI), ejection volume (EV) and residual fraction (EF) obtained on the two separate occasions were small (r = 0.81 approximately 0.95; ICC = 0.94 approximately 0.99), whereas differences in ejection fraction (EF), residual volume (RV) and venous outflow (OF) measurements were much larger (r = 0.50 approximately 0.61; ICC = 0.58 approximately 0.95). The findings demonstrate that evaluation of blood flow in the lower limbs of healthy individuals using air plethysmography is reliable in test-retest measures, suggesting that this technique represents a sensitive method for quantifying changes in parameters of arterial and venous functions of the lower extremity.     

Short-term therapy with relatively low-dose cerivastatin improves endothelial function independently of its lipid-lowering effect: Evaluation of brachial artery vasodilatation using B-mode ultrasound imaging

Background and Objective Administration of 0.4 to 0.8 mg of cerivastatin per day for 2 weeks has been reported to have pleiotropic effects and improve endothelial function. Whether low-dose cerivastatin would produce these rapid pleiotropic effects in the clinical setting remains uncertain, however. We investigated the effect of short-term therapy with relatively low-dose cerivastatin (0.15 mg/day) on endothelial function, thrombostatic parameters, and C-reactive protein (CRP) levels in hypercholesterolemic patients. Methods Thirteen patients with LDL-cholesterol>160 mg/dl were treated with daily doses of 0.15 mg of cerivastatin for 2 weeks. Endothelial function, thrombostatic parameters (tissue-type plasminogen activator [t-PA], plasminogen activator inhibitor type 1 [PAI-1], and CRP were estimated at baseline and again after 2 weeks of treatment. Endothelial function was measured as flow-mediated vasodilation. Flow-mediated vasodilatation was assessed by measuring the percent change in the diameter of the brachial artery in response to reactive hyperemia using high-resolution ultrasound. Endothelium-independent vasodilatation was also measured using sublingual nitroglycerin. Results No major complications developed after the treatment. Total cholesterol decreased significantly, from 258±32 to 211±21 mg/dl, and LDL-cholesterol also decreased from 171±15 to 133±16 mg/dl after the treatment. Flow-mediated vasodilatation increased significantly, from 4.6±1.3 percent to 8.7±3.5 percent after 2 weeks of therapy, although endothelium-independent vasodilatation was not affected (9.5±2.4% vs 8.8±3.1%). No relation was found between percent change in flow-mediated vasodilatation and improvement in levels of LDL-cholesterol after therapy (r=0.07). PAI-1, t-PA, and CRP were not significantly changed by 2 weeks of therapy. Conclusions (1) Evaluating vasodilation of the brachial artery with B-mode ultrasound imaging was useful in investigating the effect of statin on endothelial function. (2) Although no effect was detected in PAI-1, t-PA, or CRP, relatively low-dose cerivastatin therapy for 2 weeks improved endothelial function and lipid level independently and safely in hypercholesterolemic patients.     

Assessment of endothelial (dys)function in atrial fibrillation

Atrial fibrillation (AF) is associated with an increased risk of mortality and morbidity from stroke and thromboembolism. Endothelial damage or dysfunction may contribute to this increased risk of thromboembolism via the mediation of a prothrombotic or hypercoagulable state. However, the precise pathophysiological mechanism(s) relating endothelial (dys)function to AF and thromboembolism are yet to be fully elucidated. This review article aims to provide a comprehensive overview of endothelial (dys)function and AF, as well as the merits and limitations of the different methods used to assess endothelial function in AF.     

冷加压实验超声心动图及冠脉血流显像技术评价冠脉微循环内皮功能

目的应用冷加压实验超声心动图及冠脉血流显像技术评价冠状动脉造影结果正常的冠心病高危人群的微循环内皮功能。方法冠脉造影结果正常受检者40例,分为无冠心病危险因素的对照组20例和冠心病高危人群组20例。分别于静息状态下、冷加压实验后、舌下含服硝酸甘油后测量冠状动脉左主干内径并计算其内径变化率;测量冠状动脉左前降支舒张期峰值血流速度,并计算其流速变化率,比较两组干预状态下的内径变化率和流速变化率。结果静息状态下两组冠脉内径及峰值流速基础值之间均无统计学差异（P〉0．05）。冷加压实验后,冠心病高危人群组冠脉内径扩张率（4．53±2．65）％、流速增加率（23．64±5．72）％,低于对照组的（11．37±3．29）％及（43．76±4．28）％（P〈0．05）。含服硝酸甘油后,两组内径变化率和流速变化率之间无统计学差异（P〉0．05）。结论冠心病高危人群在冠脉造影结果正常时可能已合并冠状动脉微循环内皮功能损伤,冷加压实验超声心动图评价冠状动脉微循环内皮功能有一定可行性。     

Diagnosis of anesthetic-induced upper airway obstruction in children using respiratory inductance plethysmography

Objective.Upper airway obstruction is the most rapid and clinically relevant cause of hypoxia during sedation and anesthesia. This study was designed to determine if respiratory inductance plethysmography (RIP) could quantify the degree of upper airway obstruction caused by induction of general anesthesia. Methods.RIP tracings were obtained during induction of general anesthesia in healthy children. Three sets of measurements were obtained during: (1) a 3 minute control period without anesthetics, (2) 3 minutes of 50% nitrous oxide, and (3) halothane administration to complete the induction of general anesthesia. Clinical impression of upper airway obstruction (none, partial, or complete) was correlated with two separate RIP analysis techniques. Results.Three hundred ninety-five breathing epochs from 20 children (ages 3–10 years) were analyzed by both phase shift and phase inversion techniques. Although both techniques had good general correlation with severity of airway obstruction, neither was sufficiently reliable for accurate prediction of severity of airway obstruction. Conclusions.We investigated two methods for analyzing RIP tracings during varying degrees of upper airway obstruction in anesthetized children. We found that neither technique was sufficiently accurate for predicting the severity of upper airway obstruction and would not be useful as a predictor of upper airway obstruction in the clinical or research settings.     

Skin vasomotion investigation: A useful tool for clinical evaluation of microvascular endothelial function?

Skin vasomotion is the rhythmic variation of skin microvessel diameter responsible for skin microcirculatory blood flow oscillation, the so called skin blood flowmotion. It can be easily investigated by means of the spectral analysis of skin laser Doppler flowmetry (LDF) signal. Experimental and clinical findings suggest that vasomotion is partially dependent on microvascular endothelial activity. Based on this, investigation of skin vasomotion, using spectral analysis of skin LDF signal has been recently proposed for the investigation of microvascular endothelial function in clinical setting. Clinical studies have demonstrated that the LDF technique coupled with spectral analysis of skin LDF tracing is a useful and accurate method for the measurement of skin microvascular endothelial-dependent vasomotion in patients with different pathological conditions. In these studies skin vasomotion investigation showed a higher sensitivity in the evaluation of skin microvascular endothelial function than tests based on the simple LDF measurement of skin blood flow response to different stimuli. Further studies are needed to evaluate whether the investigation of skin endothelial-dependent vasomotion can predict clinical and therapeutic outcomes of patients with vascular diseases.     

肥胖人群应用彩超检测血管内皮功能的临床意义

目的应用高分辨率彩超检测血管内皮功能，探讨血管内皮功能与肥胖的关系。方法应用彩超检测血管内皮功能，测量并计算体重指数、腰臀比。结果血管内皮功能障碍组体重指数、腰臀比高于正常组（P〈0．05）。结论体重指数、腰臀比与血管内皮功能有关；应用高分辨率彩超检测肥胖人群血管内皮功能的方法简单准确，临床易于推广。     

腹膜透析患者容量变化对内皮功能的影响

目的 探讨持续性非卧床腹膜透析（continuous ambulatory peritoneal dialysis,CAPD）患者容量变化对内皮功能的影响。方法 CAPD患者93例,随访6个月,应用多频生物电阻抗分析仪检测容量状态,根据随访前、后容量变化分为容量下降组30例、容量未变化组42例和容量增加组21例,采用彩色多普勒超声仪检测血流介导的扩张反应（flowmediated dilatation,FMD）,比较3组随访前、后FMD水平。结果 随访6个月时,容量下降组FMD（8.36±5.20）%较随访前（（6.05±3.76）%）明显增加（P〈0.05）,容量增加组FMD（（6.50±3.27）%）较随访前明显下降（（9.94±4.99）%）（P〈0.01）,容量未变化组FMD（（6.81±3.80）%）与随访前（（6.80±5.35）%）比较差异无统计学意义（P〉0.05）,且容量下降组FMD明显高于容量未变化组和容量增加组（P〈0.05）。结论 CAPD患者容量与FMD纵向变化密切相关,容量对内皮功能有重要影响。     

Inductive plethysmography to control volume-targeted ventilation for leak compensation

OBJECTIVE: Volume-targeted ventilation is associated with poor compensation for leaks yet is frequently used in neuromuscular patients, many of whom experience mouth leaks. Our objective was to test the feasibility and efficacy of a prototype ventilator designed to achieve leak compensation by feed-back control of the actual tidal volume based on either the volume blown to the expiratory circuit (VTEVC-compensation) or the tidal volume measured by inductive plethysmography (VTplet-compensation). DESIGN AND SETTING: Randomized, cross-over, physiological study in a physiological ward of a university teaching hospital. PARTICIPANTS: Nine normal individuals. INTERVENTION: Subjects tested volume-targeted assist-control ventilation without compensation, with VTEVC-compensation, and with VTplet-compensation. Tests were done with the mouth closed, with mouth leaks during inspiration, and with mouth leaks during expiration. MEASUREMENTS AND RESULTS: With inspiratory mouth leaks compared to mouth closed, the delivered volume remained unchanged without leak compensation, increased to 143 +/- 30% with VTEVC-compensation, and increased to 132 +/- 17% with VTplet-compensation; the expired tidal volume decreased to 46 +/- 24% without compensation, 66 +/- 20% with VTEVC-compensation, and 68 +/- 23% with VTplet-compensation. With expiratory mouth leaks, the ventilator-delivered volume and expired tidal volume were unchanged with no compensation and with VTplet-compensation; they increased with VTEVC-compensation. CONCLUSION: Leak compensation can be achieved during volume-targeted ventilation. VTEVC-compensation and VTplet-compensation were equally effective in compensating for inspiratory leaks, and VTplet-compensation also performed well when expiratory leaks occurred.     

二甲双胍对2型糖尿病血管内皮功能的影响

目的：研究二甲双胍对2型糖尿病血管内皮功能的影响。方法93例血糖控制不满意的2型糖尿病患者随机分为二甲双胍组（500nag,3次／d）及吡格列酮组（15mg,1次／d）,疗程12个月。观察血管内皮功能的变化。结果与治疗前相比,治疗12个月后两组患者的血糖、胰岛素抵抗指数均显著下降,空腹及餐后胰岛素水平、胰岛素功能均显著升高,差异具有统计学意义（均P〈0．05）。治疗12个月后两组血糖、胰岛素抵抗指数、胰岛素水平、胰岛素功能比较,差异均无统计学意义（均P〉0．05）;但治疗12个月后二甲双胍组的体质量指数低于吡格列酮组,差异具有统计学意义（P〈0．05）。与治疗前相比,治疗12个月后两组患者的血管内皮功能均显著改善,差异具有统计学意义（均P〈0．05）,但治疗12个月后二甲双胍组的血管内皮功能改善优于吡格列酮组,差异具有统计学意义（P〈0．05）。结论二甲双胍与吡格列酮两种药物对2型糖尿病患者均具有明显的降糖、改善胰岛素功能、降低胰岛素抵抗及改善血管内皮功能的作用。在降低体质量指数及改善血管内皮功能方面,二甲双胍优于吡格列酮。     

黄芪失笑散对血管内皮功能的影响

目的观察黄芪失笑散对大鼠血管内皮功能的保护作用。方法将SD大鼠随机分为正常对照组、模型组、氟伐他汀组、黄芪失笑散大、中、小剂量组共6个实验组，除正常对照组外分别予以高脂饲料喂养，12周时观察血清一氧化氮（NO）、血浆内皮素（ET）的变化。结果黄芪失笑散各剂量组均能明显升高NO，降低酊，与模型组比较有显著差异（P〈0．05），作用与氟伐他汀组相当（P〉0．05）。结论黄芪失笑散具有调节NO／ET的平衡，有效保护血管内皮细胞的功能。     

Evaluation of fatigue by using acceleration plethysmography

We evaluated the fatigue of patients with chronic fatigue syndrome by using acceleration plethysmography. The changes in the acceleration plethysmography were relatively dominant in the sympathetic nervous system from the viewpoint of the autonomic nervous system, and the fluctuation in the time-series data of the acceleration plethysmography was decreased from the viewpoint of chaos or complexity system. We found the relation between the level of fatigue and the changes in acceleration plethysmography. Therefore, the acceleration plethysmography might be useful for the evaluation of fatigue.     

2型糖尿病患者餐后代谢对内皮功能的影响

目的：研究2型糖尿病患者餐后代谢对内皮功能影响。方法：60例2型糖尿痛患者根据餐后代谢状况分为餐后代谢正常组(正常组)以及餐后代谢异常组(异常组)。观察其空腹血糖、餐后血糖、餐后三酰甘油、一氧化氮、内皮素以及内皮依赖性血管舒张功能变化。结果：两组空腹血糖无差异，与正常组相比较异常组餐后血糖、餐后三酰甘油浓度上升。血浆一氧化氮浓度下降。内皮素浓度上升，内皮依赖性血管舒张功能减退。结论：餐后代谢影响2型糖尿痛患者血管内皮功能。     

Fat distribution and endothelial function in normal-overweight menopausal women

BACKGROUND: Adipose tissue is not an inert deposit of fat; in the truncal area, it seems to be metabolically active, due to the adipokines produced locally. These substances are related to insulin resistance, inflammation and atherosclerotic damage to the vascular system. The development of ultrasound methodologies enable better estimation of fat distribution and more detailed investigation of the metabolic aspects of the fat depots and their impact on the initial stages of atherosclerosis. AIM OF THE STUDY: To investigate the influence of abdominal fat on endothelial function, the initial stages of atherosclerotic vascular damage and its relationship with inflammatory status in normal-overweight subjects [n. 162, body mass index (BMI) >25 kg/m(2) to <30 kg/m(2)]. METHODS: A total of 162 Caucasian postmenopausal women (mean age 54 +/- 4 years, menopausal age 8 +/- 4 years) were subdivided on the basis of the median value of the visceral fat distribution and associations with brachial flow-mediated vasoactivity (FMV), BMI, intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), total and LDL cholesterol investigated. RESULTS: Subjects with lower levels of visceral fat had a higher brachial FMV (7.9 +/- 4.3 vs. 5.1 +/- 3.2%, P < 0.05) and lower BMI, waist, sICAM-1, sVCAM-1, total and LDL cholesterol. In univariate analyses, abdominal visceral fat showed a direct correlation with sICAM-1 (r = 0.43, P < 0.001), and an inverse correlation with FMV (r = -0.49, P < 0.01). Moreover an indirect relationship emerged between brachial FMV and sICAM-levels (r = -0.36, P < 0.05). In a multivariate analysis the predictive variables for brachial FMV were LDL cholesterol (beta = -0.22, P < 0.05), visceral fat (beta = -0.32, P < 0.05), sICAM-1 (beta = -0.18, P < 0.05), HDL cholesterol (beta = 0.25, P < 0.05) and brachial diameter (beta = -0.27, P < 0.05). Subcutaneous fat and triglycerides were also included in the model. CONCLUSIONS: In Caucasian normal-overweight women, visceral fat thickness was directly associated with the level of soluble ICAM-1 and inversely with FMV, thereby showing its relevance to endothelial function and the inflammatory state.