We introduce a novel paradigm to unobtrusively and optically measure blood pressure (BP) without calibration. The algorithm combines photoplethysmography (PPG) waveform analysis and biometrics to estimate BP, and was evaluated in subjects with various age, height, weight and BP levels (n = 1249). In the young population (<50 years old) with low, medium and high systolic blood pressures (SBP, <120 mmHg; 120–139 mmHg; ≥140 mmHg), the fitting errors are 6.3 ± 7.2, −3.9 ± 7.2 and −20.2 ± 14.2 mmHg for SBP respectively; In the older population (>50 years old) with the same categories, the fitting errors are 12.8 ± 9.0, 0.5 ± 8.2 and −14.6 ± 11.5 mmHg for SBP respectively. A simple personalized calibration reduces fitting errors significantly (n = 147), and good peripheral perfusion helps to improve the fitting accuracy. In conclusion, PPG may be used to calculate BP without calibration in certain populations. When calibrated, it shows great potential to serially monitor BP fluctuation, which can bring tremendous economic and health benefits.

Background Although observational studies have reported associations between serum C-reactive protein (CRP) concentration and risks of lung, breast, and colorectal cancer, inconsistent or absent evidences were showed for other cancers. We conducted a pan-cancer analysis to comprehensively assess the role of CRP, including linearity and non-linearity associations. Methods We analyzed 420,964 cancer-free participants from UK Biobank cohort. Multivariable-adjusted Cox proportional hazards model was conducted to evaluate the observed correlation of CRP with overall cancer and 21 site-specific cancer risks. Furthermore, we performed linear and non-linear Mendelian randomization analyses to explore the potential causal relation between them. Results During a median follow-up period of 7.1 years (interquartile range: 6.3, 7.7), 34,979 incident cancer cases were observed. Observational analyses showed higher CRP concentration was associated with increased risk of overall cancer (hazard ratio (HR) = 1.02, 95% CI: 1.01, 1.02 per 1mg/L increase, P < 0.001). There was a non-linear association between CRP and overall cancer risk with inflection point at 3mg/L (false-discovery rate adjust (FDR-adjusted) Poverall < 0.001 and FDR-adjusted Pnon-linear < 0.001). For site-specific cancer, we observed positive linear associations for cancers of esophagus and stomach (FDR-adjusted Poverall < 0.050 and FDR-adjusted Pnon-linear > 0.050). In addition, we also observed three different patterns of non-linear associations, including “fast-to-low increase” (head and neck, colorectal, liver, lung, kidney cancer, and non-Hodgkin lymphoma), “increase-to-decrease” (breast cancer), and “decrease-to-platform” (chronic lymphocytic leukemia). Furthermore, the inflection points of non-linear association patterns were consistently at around 3mg/L. By contrast, there was no evidence for linear or non-linear associations between genetically predicted CRP and risks of overall cancer or site-specific cancers. Conclusions Our results indicated that CRP was a potential biomarker to assess risks of overall cancer and 12 site-specific cancers, while no association were observed for genetically-predicted CRP and cancer risks.

The primary aim of the present study was to investigate the short-term effects of surgical left cardiac sympathetic denervation (LCSD) on the QT interval and heart rate in patients with congenital long QT syndrome (LQTS). Left cardiac sympathetic denervation was performed in five LQTS patients who had a history of syncope. The patients' 12-lead and 24-h Holter monitoring ECG was recorded 24 h before and 24 h after LCSD. Treadmill exercise tests were also performed before and 6 days after surgery to assess changes in heart rate and the QT interval after surgery. Left cardiac sympathetic denervation was successful in all patients. The mean value of the corrected QT interval (QTc) in the five patients decreased from 0.59+/-0.05 to 0.48+/-0.04 s (P=0.006) immediately after the procedure and remained short (0.47+/-0.04, P<0.05) after a 21-month follow-up. The mean value of QTc on the 24-h Holter monitoring ECG also decreased in all patients (0.67+/-0.07 vs 0.60+/-0.05 s, P<0.01). The mean, maximum, and minimum heart rate on the 24-h ECG remained unchanged (P>0.05). The maximum heart rate during the exercise tests decreased from 162+/-4 beats/min before surgery to 129+/-10 beats/min (P<0.01). The exercise-induced increase in QTc remained unchanged after the surgery (P>0.05). Although four of the five patients were syncope-free until 21 months postoperatively, the remaining patient had a recurrence of syncope, requiring an increased dose of beta blocker. These findings indicate that LCSD shortens QTc and diminishes the exercise-induced increase in heart rate whereas the resting heart rate and exercise-induced increase in QTc remain unchanged. These results may have implications for the effectiveness and limitations of LCSD.

Objective. In this study, we aimed to estimate blood pressure (BP) from in-ear photoplethysmography (PPG). This novel implementation provided an unobtrusive and steady way of recording PPG, whereas previous PPG measurements were mostly performed at the wrist, finger, or earlobe. Methods. The time between forward and reflected PPG waves was very short at the ear site. To minimize errors introduced by feature extraction, a multi-Gaussian decomposition of in-ear PPG was performed. Both hand-crafted and whole-based features were extracted and the best combination of features was selected using a backward-search wrapper method and evaluated by the Akaike information criteria. Hemodynamic parameters such as compliance and inertance were estimated from a four-element Windkessel (WK4) model, which was used to pre-classify PPG signals and generate different BP estimation algorithms. Calibration was done by using previous measurements from the same class. To validate this novel approach, 53 subjects were recruited for a one-month follow-up study, and 17 subjects were recruited for a two-month follow-up study. Calibrated systolic BP estimation accuracy was significantly improved with inertance-based pre-classification, while diastolic BP showed less improvement. Results. With proper feature selection, pre-classification and calibration, we have achieved a mean absolute error of 5.35 mmHg for SBP estimation, compared to 6.16 mmHg if no pre-classification was carried out. The performance did not deteriorate in two months, showing a decent BP trend-tracking ability. Conclusion. The study demonstrated the feasibility of in-ear PPG to reliably measure BP, which represents an important technological advancement in terms of unobtrusiveness and steadiness.