UNASSIGNED: Non-invasive estimation of central blood pressure (BP) may have better prognostic value than brachial BP. The accuracy of central BP is limited in certain populations, such as in females and the elderly. This study aims to examine whether statistical modeling of central BP for clinical and hemodynamic parameters results in enhanced accuracy.
UNASSIGNED: This study is a cross-sectional analysis of 500 patients who underwent cardiac catheterization. Non-invasive brachial cuff and central BP were measured simultaneously to invasive aortic systolic BP (AoSBP). Central BP was calibrated for brachial systolic (SBP) and diastolic BP (Type I calibration; C1SBP) or brachial mean and diastolic BP (Type II calibration; C2SBP). Differences between central SBP and the corresponding AoSBP were assessed with linear regression models using clinical and hemodynamic parameters. These parameters were then added to C1SBP and C2SBP in adjusted models to predict AoSBP. Accuracy and precision were computed in the overall population and per age or sex strata.
UNASSIGNED: C1SBP underestimated AoSBP by 11.2 mmHg (±13.5) and C2SBP overestimated it by 6.2 mmHg (±14.8). Estimated SBP amplification and heart rate were the greatest predictors of C1- and C2-AoSBP accuracies, respectively. Statistical modeling improved both accuracy (0.0 mmHg) and precision (±11.4) but more importantly, eliminated the differences of accuracy seen in different sex and age groups.
UNASSIGNED: Statistical modeling greatly enhances the accuracy of central BP measurements and abolishes sex- and age-based differences. Such factors could easily be implemented in central BP devices to improve their accuracy.

Calibration affects central blood pressure (BP) estimation accuracy. Factors influencing the accuracy of noninvasive central BP measurement, type of calibration method implemented (systolic/diastolic BP or mean/diastolic BP), and type of BP measurement device used (devices using the transfer function method, directly measurement from the carotid artery, and the transfer function-like method), were investigated. Fifty participants (aged 62.4 ± 8.9 years) without overt heart diseases were recruited. Invasive aortic and radial BP was measured. Simultaneously, noninvasive central BP was measured using three types of devices. The mean invasive aortic BP was 127 ± 19/95 ± 14 mmHg. Noninvasive central BP tended to be slightly lower than invasive BP, though without statistical significance. The type of calibration method did not significantly influence the noninvasive cSBP measurements (p ≥ 0.24). Results from cuff-based devices were significantly lower than invasive measurements (p = 0.04). Multiple regression analyses showed that gender was significantly correlated with the accuracy of noninvasive cSBP measurement. In conclusion, noninvasive cSBP measurements are comparable to invasive measurements but might underestimate true cSBP. The type of device may affect the accuracy of measurement. Either of the two calibration methods is acceptable.

Accurate measurement of blood pressure (BP) is extremely important in the management of sick preterm newborns. The primary objective of this study was to compare non-invasive blood pressure measurement (NIBP) with invasive blood pressure measurement (IBP) using peripheral arterial cannulation (PAC) in preterm neonates < 37 weeks in the neonatal intensive care unit.
Preterm neonates needing PAC were prospectively enrolled in the study. NIBP measurements were taken in the same limb as that of peripheral arterial line. Initially IBP was recorded followed by NIBP within 1 min using the same monitor. These were called as paired measurements since they are taken within 1 min of each other.
Seventy-three preterm infants with 1703 paired measurements were included in the final analysis (median gestational age 32 weeks, IQR 30-34 weeks, median birth weight 1540 g, IQR 1160-2100 g). In preterm infants not receiving vasoactive agents (n = 51, 1428 paired measurements, Bland-Altman analysis for agreement between invasive mean blood pressure (MBP) and non-invasive mean BP revealed a bias of -2.9123 mmHg (SD 7.8074). The 95% limits of agreement were from -18.2157 to 12.3893 mmHg. In preterm infants with hypotension, we detected a bias of -3.9176 mmHg (SD 5.1135) between invasive MBP and non-invasive MBP. The 95% limits of agreement were from -13.9401 to 6.1048 mmHg. In normotensive preterm infants receiving vasoactive agents, we detected a bias of -0.7629 mmHg (SD 8.0539) between invasive MBP and non-invasive MBP. The 95% limits of agreement were from -16.5485 to 15.02274 mmHg.
There is poor level of agreement between IBP and NIBP measurements in sick preterm neonates, leading to overestimation or underestimation of blood pressure. The bias was less for mean BP measurements as compared with systolic BP measurements and also for normotensive neonates as compared with hypotensive neonates. Hence, NIBP may be used as a screening method in haemodynamically stable preterm infants, but infants who are haemodynamically unstable and need to be commenced on vasoactive agents should have IBP monitoring.

Objective: To analyze the mechanism of invasive blood pressure change in radial artery caused by arm elevation by observing pressure, velocity and diameter of radial artery. Methods: Twenty-six hemodynamically stable hepatobiliary surgery patients admitted to the intensive care unit from June to December 2018 after general anesthesia in Tsinghua Changgung Hospital were selected. When the arm was raised, the invasive blood pressure was recorded, and the inner diameter and blood flow velocity of the radial artery were measured by Doppler ultrasound. The data following a normal distribution were compared with paired t test. Results: After arm elevation for 30 s, systolic blood pressure of radial artery decreased and diastolic blood pressure increased significantly((107±16) mmHg vs (120±17) mmHg, (75±6) mmHg vs (71±9) mmHg, t=25.0, -12.6, both P<0.05), but there was no significant difference in mean arterial pressure ((87±10) mmHg vs (87±11) mmHg, t=1.1, P>0.05). The peak velocity, end-diastolic velocity and resistance index of the radial artery increased significantly, and the transverse and longitudinal inner diameters of the radial artery decreased significantly after the arm was elevated for 30 s (t=-63.4, -14.6, -22.5, 31.4, 25.3, all P<0.01). Conclusions: Kinetic pressure compensation and vascular resistance compensation may be the main mechanism of radial artery pressure change when the arm is elevated. Arm elevation can be used as a vascular resistance response test clinically.
目的： 通过观测桡动脉压力、流速、直径等指标，分析抬高上肢导致桡动脉有创血压改变的流体力学机制。 方法： 选择2018年6至12月期间入住清华长庚医院重症监护病房（ICU）的血流动力学稳定的肝胆外科全身麻醉手术后患者26例。分别在抬高上肢前和抬高上肢时，记录有创血压数值，并以多普勒超声测量桡动脉置管处的动脉血管内径和血流速。符合正态分布的数据比较采用配对t检验。 结果： 与抬高上肢前相比，抬高上肢30 s后桡动脉收缩压下降、舒张压上升，分别为（107±16) mmHg比（120±17) mmHg和（75±6) mmHg比（71±9) mmHg，差异均有统计学意义（t=25.0、-12.6，均P<0.05)，但平均动脉压变化差异无统计学意义[(87±10) mmHg比（87±11) mmHg，t=1.1，P>0.05]。与抬高上肢前相比，抬高上肢30 s后桡动脉收缩期峰流速、舒张期末流速和阻力指数均显著增加，而桡动脉横径与纵径则显著减小，前后比较差异均有统计学意义（t=-63.4、-14.6、-22.5、31.4、25.3，均P<0.01)。 结论： 动压代偿和血管阻力代偿可能是抬高上肢时桡动脉压力改变的主要机制，抬高上肢可以作为血管阻力反应性试验在临床应用。.

OBJECTIVE: To explore the thoracic ascending aortic （TAA） pathophysiological characteristics of heterozygous mutant Myh11 R247C/+ mice under the norepinephrine-induced hypertension mode.
METHODS: Female heterozygous mutant Myh11 R247C/+ and wild type Myh11 +/+ mice were selected as experimental group (HET group) and control group (WT group)，respectively. The hypertensive model was induced by intraperitoneal injection of norepinephrine (NE)，and TAA diameter and invasive blood pressure (Bp) data were collected dynamically in real time using high-frequency ultrasound imaging and invasive arterial blood pressure monitoring technique，so as to indirectly analyze TAA compliance of two groups of mice. At the same time，the incidences of hemothorax and TAA rupture were further analyzed by autopsy and histology.
RESULTS: After injection of NE，heterozygous mice did not show a higher Bp increase percentage in systole or diastole comparing with wildtype mice. However，heterozygous mice exhibited 17% and 32% higher TAA diameter dilation percentage than wildtype ones in systole and diastole respectively. Two heterozygous mice had TAA dissection and rupture，and the incidence of hemothorax in heterozygous mice (3/5) was higher than that in wildtype (0/5).
CONCLUSIONS: It was very likely that the altered TAA wall compliance of mutant Myh11 R247C/+ mice had led to a higher TAA dilation degree than that in wildtype，and even could be the potential reason of TAA dissection and rupture.