Ambulatory heart rate monitors and clinical electrocardiographic (ECG) devices are capable of measuring the length of consecutive cardiac periods (RR intervals). The aim of the study was to assess the agreement between the Polar 810 s heart rate monitor (Polar) and the Reynolds digital ambulatory ECG using Pathfinder software version 8.4 (Reynolds v8.4) during cycle ergometry. For this purpose, eight subjects completed incremental cycling exercise that began at 60 W and increased by 30 W each 2-minute period until volitional fatigue. Simultaneous recording of the ECG (Reynolds Pathfinder), RR interval (Polar), and respiratory parameters (Metamax 3B) were undertaken at rest and throughout the exercise period. No significant differences were found in RR intervals measured by Polar and Reynolds v8.4 at any relative intensity. Polar and Reynolds v8.4 displayed strong linear relationships at all relative intensities (r² = 0.927 to 0.998). Bland and Altman analyses between Polar and Reynolds v8.4 consistently demonstrated minimal bias in absolute RR interval (< 0.10 ms) and the limits of agreement for group differences in RR interval and heart rate were less than ± 10 ms and ± 2 beats · min^-1 for all relative intensities, respectively. Power spectral analysis provided similar results for both systems in all bandwidths studied during rest and low intensity exercise. However, significant differences and large relative limits of agreement (> 100 % of mean of paired means) were identified in UF at intensities > 40 % V·O_2max, HF at intensities > 60 % V·O_2max and LF during exercise at 80 - 100 % V·O_2max. These findings demonstrate that RR intervals and heart rate measurements obtained using Polar and Reynolds v8.4 are in good agreement. However, caution should be exercised when interpreting spectral analysis of RR interval data derived from different acquisition systems during physical activity.

Sample entropy (SampEn) is a measure of the complexity of data. Few studies have compared the SampEn of electrocardiographic cardiac interval (RR) data (SampEn-RR) during differing physiological states, and none have examined SampEn for the corresponding QT interval (SampEn-QT). The aim of this study was to quantify SampEn-RR and SampEn-QT during rest and for a range of exercise workloads. Specific objectives were to assess both the utility of SampEn for discriminating between physiological states and the relationship of SampEn-RR with traditional measures of heart rate variability (HRV). Twelve males of similar age, mass and aerobic fitness participated. A three-lead ECG was recorded continuously during pre-exercise, progressive bicycle exercise and recovery, and beat-to-beat RR and QT intervals were quantified for sinus beats. SampEn and HRV were calculated within consecutive 1 min periods throughout. Consistent estimation of SampEn-RR and SampEn-QT was possible with an appropriate choice of SampEn parameters. SampEn-RR was sensitive to differing physiological conditions, but its discriminating ability was poorer than that of linear HRV indices. SampEn-RR was also negatively correlated with normalized LF and LF/HF parameters. We interpret changes in SampEn for RR and QT data in terms of the altered autonomic nervous system (ANS) control of either the atrial or the ventricular myocardium (or both) during discrete physiological states. We speculate that greater complexity in QT data might be explained by a direct ANS influence on the ventricular myocardium.

We conducted a six-month randomised controlled trial of home telemonitoring for patients with chronic obstructive pulmonary disease (COPD). A total of 40 stable patients with moderate to severe COPD who had completed pulmonary rehabilitation took part. They were randomised to receive standard care (controls) or standard care plus home telemonitoring (intervention). During the monitoring period, patients in the telemonitoring group recorded their symptoms and physical observations twice daily. The data were transmitted automatically at night via the home telephone line. Nurses could access the data through a website and receive alerting email messages if certain conditions were detected. The patients completed the St George's Respiratory Questionnaire, Hospital Anxiety and Depression and the EuroQoL EQ-5D quality of life scores before and after pulmonary rehabilitation, and then periodically during the trial. There were significant and clinically important improvements in the scores immediately following pulmonary rehabilitation, but thereafter there were no differences in quality of life scores between the groups at any time, or consistently within either group over time. The study showed that telemonitoring was safe but, despite being well used, it was not associated with changes in quality of life in patients who had stable COPD.

Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive and life-limiting condition. From a healthcare perspective it is vital to establish effective methods of improving the quality of remaining life in these patients. This requires a detailed understanding of the multiple impacts of an IPF diagnosis on the individual. We sought to understand how patients coped with their initial diagnosis, how they live with the disease day-to-day, and their experiences and opinions of the professional support they receive. A patient-centred approach was used to explore the social, psychological and physical impacts of IPF. Semi-structured interviews were conducted by an experienced academic. Interview questions were written by the researchers but guided by informal conversations with patients and clinicians. An inductive thematic approach was used to analyse the data, allowing us to identify common themes in the patients’ experiences. Of fifty invited participants, ten took part in the study (aged 53–81 years; 9 male). Inductive analysis of interviews identified seven second-order themes and eleven first-order themes, represented by two General Dimensions: ‘Patient experience with the condition’ and ‘Patient-led recommendations for practice’. The key message on ‘coping’ in these patients was that acceptance of their condition led to a sense of optimism. Participants reported using appraisal-focused coping strategies to change their perspectives (thinking positively) and emotion-focused strategies to overcome depression (the main opportunity for emotional expression being an IPF support group). The support group also facilitated problem-focused coping: individuals exchanged knowledge and experience and gave one another tips on how to live with their condition. Health professionals should provide patients with information that focuses on living with IPF, encouraging them to make lifestyle changes and adaptations to improve quality of life. Family members should receive education about IPF so that they can support such changes. Patients should be encouraged to join a support group and to participate in physical activity (again preferably group-based). This study offers novel findings that will help inform much-needed changes in the practice of supporting IPF patients to cope with their diagnosis and disease progression.

There is at present no reliable clinical technique for the assessment of cardiac electrophysiological activity in the fetus. There are two primary requirements of this type of monitoring: (i) sequential assessment of morphological and temporal parameters of cardiac electrical activity during advancing gestation, and (ii) description of the cardiac electrical activity in terms of an electrophysiologically realistic model. Fetal electrocardiography may be performed using maternal abdominal electrodes but this is only reliable prior to the 27th week of gestation. This is primarily because of the electrically insulating effects of the vernix caseosa and the existence of preferred conduction pathways between the fetal heart and maternal abdomen after this time. Fetal magnetocardiography is largely unaffected by these factors and so enables a reliable assessment of fetal electrocardiological activity throughout the second and third trimesters of pregnancy. This method can also be used to model fetal electrophysiological activity in terms of a current dipole or magnetic dipole. The vectorcardiogram is a plot of the dynamic change in dipole parameters during the cardiac cycle, allowing the study of growth-related or pathology-related electromagnetic changes in the heart. Fetal magnetocardiography and the fetal vectorcardiogram may thus provide important additions to current methods of antenatal monitoring.