Determination of Bioelectrical Impedance Thresholds for Early Detection of Breast Cancer-related Lymphedema

Background: Bioelectrical impedance technology is a common technique used for the early detection of breast cancer-related lymphedema (BCRL). However, studies on the threshold value established by Inbody 720 device (Biospace, Korea) have been extremely limited. We aimed to determine its reference range and cutoff values.Methods: All patients were recruited from October 2017 to October 2019 at the Peking University People''s Hospital Breast Center. In total, 82 patients with unilateral BCRL and 1305 healthy subjects were recruited in this study. We measured the extracellular fluid (ECF) ratio, extracellular water (ECW) ratio, as well as the single-frequency bioimpedance analysis (SFBIA) ratios at 1 and 5 kHz with the Inbody 720 device. The Youden index-based cutoff points, mean + 2SD and mean + 3SD values of these four indicators for both dominant and nondominant arms were also calculated.Results: Data were collected from 1387 women, including healthy subjects and patients with lymphedema. All statistical analyses were performed with SPSS. Significant differences were found between the two groups in the ECW, ECF, and SFBIA ratios. For the dominant affected arms, the Youden index-based cutoff points for the ECF, ECW, as well as SFBIA ratios at 1 and 5 kHz were 1.009, 1.008, 1.068, and 1.068, respectively. For the nondominant affected arms, the Youden index-based cutoff points were 1.014, 1.013, 1.047, and 1.048, respectively. The mean + 2 standard deviations (SD) and mean + 3SD values were also calculated.Conclusions: We determined the Youden index-based cutoff points, mean + 2SD and mean + 3SD values of the ECF, ECW, as well as SFBIA ratios at 1 and 5 kHz for both dominant and nondominant arms with data from 1305 healthy subjects. Next, the Youden index-based cutoff points, the mean + 2SD and mean + 3SD values were used to recognize patients with lymphedema. We found that the Youden index-based cutoff points and the mean + 2SD showed similar identification capacity on lymphedema, and they seemed to distinguish more patients with lymphedema than mean + 3SD values.     

Sex Differences in Obstructive Sleep Apnea by Bioelectrical Impedance Analysis

Background and PurposeObesity is known of one of the risk factors for obstructive sleep apnea (OSA). Although body mass index (BMI) can be an indicator for obesity, it does not represent the actual body composition of fat or muscle. We hypothesized that bioelectrical impedance analysis (BIA) can help analyze the fat and muscle distributions in males and females with OSA.MethodsThis study screened subjects who visited the Department of Neurology, Samsung Medical Center, Seoul, Korea due to sleep disturbances with symptoms suggestive of OSA from December 2017 to December 2019. All subjects underwent overnight type I polysomnography (PSG) and BIA.ResultsPSG and BIA were completed in 2,064 OSA patients who had an apnea-hypopnea index (AHI) of ≥5/hour (77.1% males and 22.9% females). The females had remarkably higher fat indicators and lower muscle indicators. The AHI was significant correlated with all BIA parameters in all OSA patients: body fat mass (ρ=0.286, p<0.001), percentage body fat (ρ=0.130, p<0.001), visceral fat area (VFA) (ρ=0.257, p<0.001), muscle mass (ρ=0.275, p<0.001), and skeletal muscle mass (SMM) (ρ=0.270, p<0.001). The correlations in males were similar to those in all patients, where those in females were not. In females with OSA, all of the BIA fat indicators were correlated with AHI, whereas the muscle indicators were not. Adjusting age and BMI when analyzing the SMM/VFA ratio showed a strong correlation in males with OSA (p=0.015) but not in females with OSA (p=0.354).ConclusionsThis study has revealed that the body composition of fat and muscle has different patterns in OSA patients. The SMM/VFA as measured using BIA is the factor most significantly associated with AHI in males but not in females after adjusting for age and BMI.     

Cardiac output during exercise: A comparison of four methods

Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from the right atrium (Q_Fick‐M), Innocor (inert gas rebreathing; Q_Inn), Physioflow (impedance cardiography; Q_Phys), and Nexfin (pulse contour analysis; Q_Pulse) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (F_iO₂ = 12%). While all four methods reported a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO₂) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q_Fick‐M, Q_Inn, Q_Phys and Q_Pulse, respectively; P = 0.001] and hypoxia (7.2 ± 0.7, 4.9 ± 0.5, 6.4 ± 0.8 and 5.1 ± 0.4 L/min per L/min; P = 0.04). In hypoxia, the increase in the Q/VO₂ slope was not detected by Nexfin. In normoxia, Q increases by 5–6 L/min per L/min increase in VO₂, which is within the 95% confidence interval of the Q/VO₂ slopes determined by the modified Fick method, Physioflow, and Nexfin apparatus while Innocor provided a lower value, potentially reflecting recirculation of the test gas into the pulmonary circulation. Thus, determination of Q during exercise depends significantly on the applied method.     

Cold pain prolongs gastric emptying of liquid but not solid meal: an electrical impedance tomography (EIT) study

Stressful stimuli are reported to affect gastric emptying. However, methods for measuring gastric emptying are, in themselves, stressful. Electrical impedance tomography (EIT) is a method for measuring gastric emptying noninvasively. We used EIT to measure gastric emptying of liquid and solid meals to determine the effect of cold pain stress on gastric emptying. EIT (DAS-01P APT system; University of Sheffield, UK) was carried out in six healthy women (age, 21.6 ± 0.4 [mean ± SD] years) who had ingested a liquid (potage, 263 g; 139 kcal) or solid (beef patty, 205 g; 435 kcal) test meal. Cold pain stimuli consisted of repeated immersions of the subject's non-dominant hand into ice water (4°C) for 1 min, with a 15-s recovery period between immersions, for a total of 20 min. For the control stimulus, water at 37°C was used. The cold pain stimulus was applied immediately after the ingestion of a test meal. All studies were carried out randomly in each subject at intervals of more than 1 week. With cold pain, the half emptying time of the liquid meal was significantly greater than that with the control stimulus (47.6 ± 26.1 min vs 28.1 ± 10.8 min, P < 0.05). For the solid meal, the half emptying time did not differ between stimuli (101.9 ± 44.8 min with cold pain vs 92.6 ± 30.5 min with control stimulus). There were no significant differences in lag time between the liquid and solid meals. Cold pain stress delayed gastric emptying of liquid but not solid meals. Received: September 28, 1999 / Accepted: February 25, 2000     

The G972R variant of the Insulin Receptor Substrate-1 (IRS-1) gene, body fat distribution and insulin-resistance

Aims/hypothesis. Insulin resistance is recognised as the core factor in the pathogenesis of Type II (non-insulin-dependent) diabetes mellitus, hypertension and atherosclerosis. Several studies indicate the possible role of mutations of the insulin receptor substrate-1 (IRS-1) gene in the pathogenesis of insulin-resistance and suggest a possible interaction between the IRS-1 gene and obesity, either by an effect on the development of obesity or by causing or aggravating the obesity-associated insulin resistance. Therefore, the prevalence of the G972R mutation of the IRS-1 gene was compared in 157 non-diabetic obese subjects (BMI > 30 m/kg²) and in 157 lean subjects (BMI < 28 m/kg²). By investigating the relation between this IRS-1 mutation, measures of obesity and metabolic parameters, we explored the possible influence of this mutation on body fat distribution and insulin resistance. Methods. The G972R mutation was detected by PCR amplification and BstN-1 restriction enzyme digestion. Data were analysed by univariate and multivariate analysis. Results. The G972R allele was significantly more frequent in obese subjects than in lean subjects (p < 0.002); however, no difference was found between centrally and peripherally obese subjects. Obese G972R carriers had significantly higher BMI (p < 0.001), fasting insulin (p < 0.01), triglycerides (p < 0.03) and HOMA_IR (p < 0.001) than obese non-carriers. No differences were observed between G972R carriers and non-carriers among control subjects. Multivariate analysis confirmed that the IRS-1 G972R mutation was significantly and independently associated with reduced insulin sensitivity (p < 0.009) in the obese group. Conclusion/interpretation. The G972R mutation of the IRS-1 gene associates with obesity, but not with fat distribution, in this Italian cohort, and within the obese subjects this IRS-1 variant strongly associates with metabolic parameters suggesting greater insulin-resistance. These findings indicate a possible interaction between the IRS-1 variant and obesity in worsening insulin sensitivity. [Diabetologia (2001) 44: 367–372] Received: 11 August 2000 and in revised form: 25 October 2000     

Gastroesophageal reflux disease and patterns of reflux in patients with idiopathic pulmonary fibrosis using hypopharyngeal multichannel intraluminal impedance

Idiopathic pulmonary fibrosis (IPF) is a diffuse fibrotic lung disease of unknown etiology. The association between IPF and gastroesophageal reflux disease (GERD) has been suggested. The objective of this study was to determine the prevalence of GERD and assess the proximity of reflux events in patients with histologically proven IPF using hypopharyngeal multichannel intraluminal impedance (HMII). This is a retrospective review of prospectively collected data from patients with histologically confirmed IPF (via lung biopsy) who underwent objective esophageal physiology testing including high‐resolution manometry and HMII. Defective lower esophageal sphincter (LES) was defined as either LES pressure of <5.0 mmHg, total length of LES of <2.4 cm, or intra‐abdominal length of LES of <0.9 cm. Abnormal esophageal motility was considered present when failed swallows ≥30% and/or mean wave amplitude <30 mmHg was present. HMII used a specialized impedance catheter to directly measure laryngopharyngeal reflux (LPR) and full column reflux (reflux 2 cm distal to the upper esophageal sphincter). Based on the previous study of healthy subjects, abnormal proximal exposure was considered present when LPR ≥1/day and/or full column reflux ≥5/day were present. From October 2009 to June 2011, 46 patients were identified as having pulmonary fibrosis and sufficient HMII data. Of 46, 10 patients were excluded because of concomitant connective tissue diseases, and 8 patients were excluded because they had undergone lung transplantation, which may impact the patterns of reflux. The remaining 28 patients with histologically confirmed IPF (male 16, female 12) were included in this study. Mean age and BMI were 60.4 years (range, 41–78) and 28.4 (range, 21.1–38.1), respectively. All patients except one were symptomatic; 23 (82%) patients had concomitant typical GERD symptoms such as heartburn, whereas 4 (14%) patients had isolated pulmonary symptoms such as cough. Esophageal mucosal injury such as esophagitis and Barrett's esophagus was found in 17 (71%) patients, whereas hiatal hernia was found in 19 (73%) patients. Abnormal proximal exposure, which occurred almost exclusively in the upright position, was present in 54% (15/28) of patients. There was no significant difference in clinical symptoms, objective findings of GERD, and pulmonary functions such as forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and diffusing capacity of the lung for carbon monoxide (DLCO) between patients with and without abnormal proximal exposure. Although the total number of reflux events was significantly higher in patients with abnormal proximal exposure, a large number of patients had a negative DeMeester score regardless of whether abnormal proximal exposure was present (patients with, 80%; those without, 85%). Patients with abnormal proximal exposure more likely had a defective LES compared with those without (93% vs. 75%). Fourteen patients (56%) had abnormal esophageal motility including aperistaltic esophagus (n = 9). This first study of HMII in patients with IPF demonstrated that GERD is highly prevalent (>70%), and abnormal proximal reflux events such as LPR and full column reflux are common despite a frequently negative DeMeester score. HMII may be beneficial in the work‐up of GERD in patients with IPF.     

无创心输出量测量系统指导下六分钟步行试验操作规范及临床应用专家共识

面对6MWT的困境,如干扰因素多、解读存在困难等,在6MWT时动态地监测血流动力学变化,可以更加精准的反映6MWT测试中心功能的变化,获取更多有用信息,使受试者获益更多。心力衰竭是多种心血管疾病（如缺血性心肌病、高血压病等）的终末阶段,均伴随着血流动力学变化。左心室充盈压力升高导致的充血是与心力衰竭相关住院最常见的因素,导致在住院前几天出现的呼吸困难、水肿和疲劳等症状。尽管住院期间的治疗减少了充血的症状和体征,在出院时仍有近一半的心衰患者表现出充血的体征,事实上,这部分患者被证明具有更高的再住院和长期死亡风险 [19, 20]。因此,对心衰患者在出院后进行血流动力学监测调整治疗方案尤为重要。近十年来,越来越多的血流动力学监测技术相继涌现,从有创到微创再到无创,尝试着用更准确、更无创、更便捷、成本更低的监测技术指导个体化治疗。 无创心脏血流动力检测技术中主要起源于20世纪60年代美国明尼苏达大学库比赛克（Kubicek）教授根据欧姆定律提出了胸腔电生物阻抗法（TEB）,用于无创心功能检查。随着心脏舒缩,血管内血流量发生变化,电流通过胸部的阻抗也产生相应变化。阻抗心动图（impedance cardiography, ICG）无创血流动力学监测正是利用胸阻抗原理,通过对心阻抗微积分血流图处理得到包括每搏输出量（stroke volume,SV）、心输出量（cardiac output,CO）、心指数（cardiac index,CI）、舒张早期充盈率（early diastolic filling rate,EDFR）、外周血管阻力（systemic vascular resistance,SVR）等参数。近年来,高清阻抗心动图（HD-ICG）技术开始得到广泛应用,可动态地监测无创心输出量（简称无创心排）,其准确性和便捷性已被认识[21]。因6WMT受非心脏因素影响较多,在HD -ICG无创血流动力学监测下同步进行6MWT,实时、连续、精准、动态监测血流动力学变化,综合进行静息评定和趋势变化分析,从而更加精准的反映6MWT测试中心功能的变化,可以更精准地评定心功能、制定更加安全的运动处方。基于此,中国健康促进基金会心脏康复发展专项基金邀请国内部分专家,经反复讨论,特制定本专家共识。