Objectives: Vascular ageing is increasingly being recognised as a vital marker of cardiovascular morbidity and mortality. Assessment of vascular stiffness is an important parameter in this context. Pulse arrival time (PAT) assessed using photoplethysmography (PPG) and digital electrocardiogram (ECG) signals is a feasible and cost-effective parameter for this assessment. However, there are few, if any, studies that have assessed the test-retest repeatability of this parameter over time. Materials and Methods: We computed PAT using finger PPG and Lead II ECG and measured it sequentially at five instances over a period of 1 month in 21 healthy adults (10 males and 11 females). Mean and diastolic blood pressure (MBP and DBP) and heart rate (HR) were also measured at each visit. A novel parameter, PAT normalised for HR of 75 (PAT-75), was also computed. PAT and PAT-75 were compared for these visits using repeated measures analysis of variance. The intraclass correlation coefficient (ICC) was used to assess the test-retest reliability of this parameter. Results: MBP, DBP, and PAT values did not show any difference between the visits. HR was significantly different between the visits. PAT-75 was significantly lower for the afternoon of day 1 as compared to the forenoon. ICC demonstrated only moderate reliability of PAT (ICC = 0.57), with further reduction observed for PAT-75 (ICC = 0.38). Conclusion: PAT was only moderately repeatable on repeated evaluation over a 1-month period. This finding may have implications for the large-scale applicability of this technology, and therefore, we propose further investigation into the repeatability of this parameter in large cohorts.

Objectives: The objective of this study was to detect the normal motor amplitude, distal latency, conduction velocity, sensory amplitude, sensory latency and F-wave latency of upper limb nerves (Median nerve, ulnar nerve and radial nerve). Materials and Methods: It was a cross-sectional study conducted in the Department of Neurology, Government Medical College, Kozhikode, between 1 January 2022 and 31 December 2022. Nerve conduction studies (NCSs) were performed prospectively in the upper limbs of 311 carefully screened, healthy individuals of either sex, who were between the ages of 13 and 60 years, belonging to the North Kerala population, using the standardised technique. Results: The study population consisted of 54% males and 46% females. The mean age, height, weight and body mass index (BMI) of the study population were 39 ± 15 years, 163 ± 12 cm, 58 ± 11 Kgs and 22 ± 2.7 Kg/m2, respectively. The motor, sensory parameters and F-wave latency of median ulnar and radial nerves were established. We obtained a significant positive correlation between motor distal latency, sensory distal latency and F-wave latency of median and ulnar and radial nerves with age, height and weight. We obtained a significant negative correlation between motor distal amplitude, sensory distal amplitude and conduction velocity of median, ulnar, and radial nerves with age, height and weight. In our study, females had faster conduction velocity, shorter F-wave latency, motor distal latency, sensory latency and higher motor amplitude and sensory amplitude than males. BMI did not have a significant correlation with nerve conduction parameters in our study. Conclusion: Normative conduction parameters of commonly tested peripheral nerves of the upper limb were established for our electrophysiology laboratory. While performing NCS, it is essential to adapt values based on physiological factors such as age, gender, height, weight and BMI, which enhance the diagnostic sensitivity of the procedure and, thus, avoid misdiagnosis and mistreatment of various demyelinating and axonal disorders.