Development of a Wearable Cardiac Monitoring System for Behavioral Neurocardiac Training: A Usability Study.

BACKGROUND: Elevated blood pressure is one of the main risk factors for death globally. Behavioral neurocardiac training (BNT) is a complementary approach to blood pressure and stress management that is intended to exercise the autonomic reflexes, improve stress recovery, and lower blood pressure. BNT involves cognitive-behavioral therapy with a paced breathing technique and heart rate variability biofeedback. BNT is limited to in-clinic delivery and faces an accessibility barrier because of the need for clinical oversight and the use of complex monitoring tools. OBJECTIVE: The objective of this project was to design, develop, and evaluate a wearable electrocardiographic (ECG) sensor system for the delivery of BNT in a home setting. METHODS: The wearable sensor system, Beat, consists of an ECG sensor and a mobile app. It was developed iteratively using the principles of test-driven Agile development and user-centered design. A usability study was conducted at Toronto General Hospital to evaluate feasibility and user experience and identify areas of improvement. RESULTS: The Beat sensor was designed as a modular patch to be worn on the user's chest and uses standard ECG electrodes. It streams a single-lead ECG wirelessly to a mobile phone using Bluetooth Low Energy. The use of small, low-power electronics, a low device profile, and a tapered enclosure allowed for a device that can be unobtrusively worn under clothing. The sensor was designed to operate with a mobile app that guides users through the BNT exercises to train them to a slow-paced breathing technique for stress recovery. The BNT app uses the ECG captured by the sensor to provide heart rate variability biofeedback in the form of a real-time heart rate waveform to complement and reinforce the impact of the training. Usability testing (n=6) indicated that the overall response to the design and user experience of the system was perceived positively. All participants indicated that the system had a positive effect on stress management and that they would use it at home. Areas of improvement were identified, which focused primarily on the delivery of training and education on BNT through the app. CONCLUSIONS: The outcome of this project was a wearable sensor system to deliver BNT at home. The system has the potential to offer a complementary approach to blood pressure and stress management at home and reduce current accessibility barriers.

Integration of vitamin A supplementation with the Expanded Programme on Immunization: lack of impact on morbidity or infant growth.

UNLABELLED: Vitamin A deficiency is associated with increased morbidity and mortality from diarrheal disease, measles, and malaria. It has been proposed that vitamin A supplementation could be linked with childhood immunization programs to improve child health. We conducted a randomized, double-blind, placebo-controlled clinical trial to evaluate the impact of linking vitamin A supplementation with the Expanded Programme on Immunization on morbidity and child growth. In West Java, Indonesia, 467 six-week-old infants were randomized to receive 7.5 mg retinol equivalent (RE), 15 mg RE, or placebo with childhood immunization contacts at 6, 10, and 14 wks and 9 mo of age. Child growth was assessed through anthropometry, and morbidity histories were obtained. Vitamin A supplementation had no apparent impact upon linear or ponderal growth or infectious disease morbidity in the first 15 mo of age when integrated with the Expanded Programme on Immunization. CONCLUSION: Although improving vitamin A nutriture is of general importance in reducing diarrheal and measles morbidity and mortality in developing countries, this clinical trial showed no apparent benefit of vitamin A capsules for infant health when given through childhood immunization programs.

Integration of vitamin A supplementation with the expanded program on immunization does not affect seroconversion to oral poliovirus vaccine in infants.

Childhood immunization programs may provide infrastructure for delivering vitamin A supplements to infants in developing countries. The effect of giving vitamin A, an immune enhancer, on antibody responses to trivalent oral poliovirus vaccine (TOPV) is unknown. A randomized, double-blind, placebo-controlled clinical trial was conducted to determine the effect of giving vitamin A simultaneously with TOPV on antibody responses to poliovirus. Infants (n = 467) received oral vitamin A, 15 mg retinol equivalent (RE), 7.5 mg RE or placebo with TOPV at 6, 10 and 14 wk of age. Antibody responses to poliovirus types 1, 2 and 3 were measured by a microvirus neutralization assay at enrollment and at 9 mo of age. Seroconversion rates to poliovirus types 1, 2 and 3 ranged from 98 to 100% in the three treatment groups, and there were no differences in mean antibody titers to poliovirus types 1, 2 and 3 among treatment groups. This study demonstrates that oral vitamin A does not affect antibody responses to poliovirus vaccine when integrated with the Expanded Program on Immunization.

Effect of vitamin A supplementation on measles vaccination in nine-month-old infants.

OBJECTIVE: Childhood immunization programs have been suggested as an infrastructure to deliver vitamin A supplements to children in developing countries. The effects of giving vitamin A, a potent immune enhancer, with measles immunization to nine-month-old infants is unknown. METHODS: A randomized, double-masked, placebo-controlled clinical trial of vitamin A, 100,000 IU at the time of standard titer Schwarz measles immunization was conducted with nine-month-old infants in Bogor District, West Java, Indonesia. Antibody titers to measles were measured at baseline and one and six months following immunization. RESULTS: 394 infants received measles immunization, and 37 infants (9.4%) had baseline antibody titers > 1:120, which is consistent with previous natural measles infection. Of the remaining infants, 98.8% seroconverted to measles, and 99.3% had titers consistent with protection against measles six months postimmunization. Seroconversion rates were similar in vitamin A and placebo treatment groups. CONCLUSION: High dose vitamin A supplementation can be given without reducing seroconversion to standard titer Schwatz measles immunization in nine-month-old infants.

PIP: The feasibility of combining vitamin A supplementation and measles immunization was investigated in a double-masked, placebo-controlled clinical trial involving 394 9-months-old infants in Bogor district, West Java, Indonesia. Vitamin A, a potent immune enhancer, has been shown to reduce child mortality by 20-50% in developing countries and is among the most cost-effective child survival interventions. 130 infants received a placebo; 132 were given 25,000 IU of vitamin A at 6, 10, and 14 weeks and 100,000 IU at 9 months; and the final 132 were given 50,000 IU of vitamin A at 6, 10, and 14 weeks and 100,000 IU at 9 months. 37 (9.4%) of the study infants had pre-immunization measles titers greater than 1:120 at 9 months of age, indicative of a previous history of natural measles infection. 98.8% of the remaining infants had seroconverted to measles 1 month after immunization, regardless of whether they received vitamin A or placebo; after 6 months, 99.3% had titers consistent with protection against measles. Geometric mean titers were 1:1772 and 1:2298 at 1 month post-immunization and 1:1164 and 1:1900 at 6 months post-immunization in infants receiving vitamin A and placebo, respectively. Since vitamin A supplementation does not interfere with seroconversion to standard titer Schwarz measles immunization, its inclusion in Expanded Program on Immunization campaigns is recommended.

Reduced seroconversion to measles in infants given vitamin A with measles vaccination.

Administration of 100,000 IU vitamin A at the time of measles immunisation is currently recommended for infants in developing countries. However, the safety and value of giving vitamin A, a potent immune enhancer, with live measles virus vaccines are unknown. We conducted a randomised, double-blind, placebo-controlled clinical trial in Indonesia to evaluate the effect of simultaneous vitamin A supplementation on the immune response to measles immunisation at six months of age. 336 infants received either vitamin A (100,000 IU) or placebo when immunised with standard-titre Schwarz measles vaccine. 82% of infants seroconverted to measles. In a multiple logistic regression model adjusting for maternal antibody titres, vitamin A supplementation was associated with a lower likelihood of seroconversion to measles (odds ratio 0.40, 95% CI 0.19-0.88), and girls were less likely to seroconvert than boys (0.34, 0.15-0.76). Immunisation with standard-titre Schwarz vaccine at six months of age in this study population is characterised by high seroconversion rates. However, simultaneous high-dose vitamin A may interfere with seroconversion to live measles vaccine in infants with maternal antibody.

PIP: In 19 villages in the Bogor District of West Java, Indonesia, between December 1992 and March 1993, pediatricians immunized 336 infants 6 months old with 0.5 ml of the standard-titer Schwarz measles vaccine and administered either 100,000 IU vitamin A (169 infants) or a placebo (167 infants) at the same time. The researchers wanted to determine the effect of vitamin A administration on antibody responses to the measles vaccination. 82% of 306 infants seroconverted to measles. About 33% of the 336 infants had no detectable maternal antibodies to measles, indicating that they were very vulnerable to measles infection. The multiple logistic regression model controlling for maternal antibody titers found that vitamin A administration reduced the likelihood of seroconversion to measles (odds ratio [OR] = 0.4). Females were less likely to seroconvert than males (OR = 0.34). At 1 and 6 months after immunization, infants who were administered vitamin A had a 25% lower geometric mean than those who were administered the placebo (p = 0.05 and 0.09, respectively). They were also less likely than the placebo group to develop a generalized rash (8.7% vs. 15.9%; p 0.05), suggesting that vitamin A may limit replication of vaccine-strain measles vaccine. These results suggest that simultaneous high- dose vitamin A may thwart seroconversion to live measles vaccine in infants with maternal antibodies. More research is needed.