Associations Between Heart Rate Variability Measured With a Wrist-Worn Sensor and Older Adults' Physical Function: Observational Study.

BACKGROUND:Heart rate variability (HRV), or variation in beat-to-beat intervals of the heart, is a quantitative measure of autonomic regulation of the cardiovascular system. Low HRV derived from electrocardiogram (ECG) recordings is reported to be related to physical frailty in older adults. Recent advances in wearable technology offer opportunities to more easily integrate monitoring of HRV into regular clinical geriatric health assessments. However, signals obtained from ECG versus wearable photoplethysmography (PPG) devices are different, and a critical first step preceding their widespread use is to determine whether HRV metrics derived from PPG devices also relate to older adults' physical function. OBJECTIVE:This study aimed to investigate associations between HRV measured with a wrist-worn PPG device, the Empatica E4 sensor, and validated clinical measures of both objective and self-reported physical function in a cohort of older adults living independently within a continuing care senior housing community. Our primary hypothesis was that lower HRV would be associated with lower physical function. In addition, we expected that HRV would explain a significant proportion of variance in measures of physical health status. METHODS:We evaluated 77 participants from an ongoing study of older adults aged between 65 and 95 years. The assessments encompassed a thorough examination of domains typically included in a geriatric health evaluation. We collected HRV data with the Empatica E4 device and examined bivariate correlations between HRV quantified with the triangular index (HRV TI) and 3 widely used and validated measures of physical functioning-the Short Physical Performance Battery (SPPB), Timed Up and Go (TUG), and Medical Outcomes Study Short Form 36 (SF-36) physical composite scores. We further investigated the additional predictive power of HRV TI on physical health status, as characterized by SF-36 physical composite scores and Cumulative Illness Rating Scale for Geriatrics (CIRS-G) scores, using generalized estimating equation regression analyses with backward elimination. RESULTS:We observed significant associations of HRV TI with SPPB (n=52; Spearman ρ=0.41; P=.003), TUG (n=51; ρ=-0.40; P=.004), SF-36 physical composite scores (n=49; ρ=0.37; P=.009), and CIRS-G scores (n=52, ρ=-0.43; P=.001). In addition, the HRV TI explained a significant proportion of variance in SF-36 physical composite scores (R2=0.28 vs 0.11 without HRV) and CIRS-G scores (R2=0.33 vs 0.17 without HRV). CONCLUSIONS:The HRV TI measured with a relatively novel wrist-worn PPG device was related to both objective (SPPB and TUG) and self-reported (SF-36 physical composite) measures of physical function. In addition, the HRV TI explained additional variance in self-reported physical function and cumulative illness severity beyond traditionally measured aspects of physical health. Future steps include longitudinal tracking of changes in both HRV and physical function, which will add important insights regarding the predictive value of HRV as a biomarker of physical health in older adults

Assessment of post-laparotomy pain in laboratory mice by telemetric recording of heart rate and heart rate variability

BACKGROUND: Pain of mild to moderate grade is difficult to detect in laboratory mice because mice are prey animals that attempt to elude predators or man by hiding signs of weakness, injury or pain. In this study, we investigated the use of telemetry to identify indicators of mild-to-moderate post-laparotomy pain. RESULTS: Adult mice were subjected to laparotomy, either combined with pain treatment (carprofen or flunixin, 5mg/kg s/c bid, for 1 day) or without pain relief. Controls received anesthesia and analgesics or vehicle only. Telemetrically measured locomotor activity was undisturbed in all animals, thus confirming that any pain experienced was of the intended mild level. No symptoms of pain were registered in any of the groups by scoring the animals' outer appearance or spontaneous and provoked behavior. In contrast, the group receiving no analgesic treatment after laparotomy demonstrated significant changes in telemetry electrocardiogram recordings: increased heart rate and decreased heart rate variability parameters pointed to sympathetic activation and pain lasting for 24 hours. In addition, core body temperature was elevated. Body weight and food intake were reduced for 3 and 2 days, respectively. Moreover, unstructured cage territory and destroyed nests appeared for 1-2 days in an increased number of animals in this group only. In controls these parameters were not affected. CONCLUSIONS: In conclusion, real-time telemetric recordings of heart rate and heart rate variability were indicative of mild-to-moderate post-laparotomy pain and could define its duration in our mouse model. This level of pain cannot easily be detected by direct observation

Multiparameter Telemetry as a Sensitive Screening Method to Detect Vaccine Reactogenicity in Mice

Refined vaccines and adjuvants are urgently needed to advance immunization against global infectious challenges such as HIV, hepatitis C, tuberculosis and malaria. Large-scale screening efforts are ongoing to identify adjuvants with improved efficacy profiles. Reactogenicity often represents a major hurdle to the clinical use of new substances. Yet, irrespective of its importance, this parameter has remained difficult to screen for, owing to a lack of sensitive small animal models with a capacity for high throughput testing. Here we report that continuous telemetric measurements of heart rate, heart rate variability, body core temperature and locomotor activity in laboratory mice readily unmasked systemic side-effects of vaccination, which went undetected by conventional observational assessment and clinical scoring. Even minor aberrations in homeostasis were readily detected, ranging from sympathetic activation over transient pyrogenic effects to reduced physical activity and apathy. Results in real-time combined with the potential of scalability and partial automation in the industrial context suggest multiparameter telemetry in laboratory mice as a first-line screen for vaccine reactogenicity. This may accelerate vaccine discovery in general and may further the success of vaccines in combating infectious disease and cancer

Employing consumer electronic devices in physiological and emotional evaluation of common driving activities

It is important to equip future vehicles with an on-board system capable of tracking and analysing driver state in real-time in order to mitigate the risk of human error occurrence in manual or semi-autonomous driving. This study aims to provide some supporting evidence for adoption of consumer grade electronic devices in driver state monitoring. The study adopted repeated measure design and was performed in high- fidelity driving simulator. Total of 39 participants of mixed age and gender have taken part in the user trials. The mobile application was developed to demonstrate how a mobile device can act as a host for a driver state monitoring system, support connectivity, synchronisation, and storage of driver state related measures from multiple devices. The results of this study showed that multiple physiological measures, sourced from consumer grade electronic devices, can be used to successfully distinguish task complexities across common driving activities. For instance, galvanic skin response and some heart rate derivatives were found to be correlated to overall subjective workload ratings. Furthermore, emotions were captured and showed to be affected by extreme driving situations

Using cardiovascular measures for adaptive automation

Adaptieve automatisering betekent zoveel als een technologisch ingerichte werkomgeving die zich aanpast aan de gebruiker. Binnen het onderzoeksgebied adaptieve automatisering worden technologische systemen ontwikkeld die flexibel zijn en zich kunnen aanpassen aan de specifieke behoeften en eisen van de individuele mens. Het idee is dat het hele systeem (mens en machine samen) het best functioneert als de werklast van de mens op een optimaal niveau wordt gehouden. Enerzijds moet voorkomen worden dat de hele taak geautomatiseerd wordt, zodat de menselijke bestuurder niet meer snel en adequaat kan ingrijpen als er iets mis gaat met het geautomatiseerde systeem. Anderzijds moet voorkomen worden dat oververmoeidheid en concentratieverlies optreden door een voortdurende (te) hoge werklast . Meten is weten. Een belangrijke eerste voorwaarde om de werklast op een adequaat niveau te houden is deze te kunnen meten. Een geschikte manier om mentale belasting te bepalen is met behulp van fysiologische methoden, in het bijzonder met behulp van hartslag, bloeddruk en ademhalingsmaten. In de literatuur is er nog enige onduidelijkheid over de relatie tussen mentale inspanning en de psychofysiologische reacties daarop. In dit proefschrift worden een aantal onduidelijkheden over deze relatie verklaard aan de hand van een onderscheid dat gemaakt wordt tussen toestand-gerelateerde (of compensatoire) effecten en korte termijn effecten die naar verwachting meer rechtstreeks verband houden met veranderingen in de taakeisen. De toestand gerelateerde effecten zijn pogingen van het lichaam om te herstellen van langdurige inspanning en terug te keren naar een evenwichtssituatie. De korte termijn effecten ontstaan doordat het lichaam reageert op momentane verschillen in werklast waar het lichaam energie voor moet leveren. In het beschreven onderzoek is een aantal experimenten in een gesimuleerde ambulancemeldkamer en in een rijsimulator uitgevoerd op basis waarvan een nieuwe methode is ontwikkeld die meer inzicht geeft in de momentane werklast van de mens. Deze methode leent zich ook uitstekend voor gebruik bij adaptieve automatisering. In het kort kan worden gezegd dat de toestandseffecten, met andere woorden het herstellen van inspanning, de effecten die door de huidige werklast worden veroorzaakt, in veel werksituaties overschaduwen. Hierdoor zijn de directe effecten van werklastveranderingen vaak niet zichtbaar. De oplossing die in dit proefschrift wordt beschreven is een keuze voor korte termijn cardiovasculaire maten. Daarmee zijn verschillen in hartslag, hartslagvariabiliteit en andere cardiovasculaire maten nog steeds zichtbaar in de korte termijn respons-patronen, ondanks de aanwezigheid van de toestandseffecten. De korte termijn analyse berust op een tijd-frequentie methode waarbij de variabiliteit van de cardiovasculaire maten wordt berekend in tijdsegmenten van 30 seconden. Deze methode is getoetst in experimenten die opnieuw in de ambulance meldkamer simulatie en rijsimulator zijn uitgevoerd. De conclusie is dat de verschillen in gevonden effecten in eerder beschreven onderzoek m.b.t. werkbelastingmaten in belangrijke mate verklaard kunnen worden uit de compenserende werking van het bloeddrukregulatie systeem. De compenserende werking van het bloeddrukregulatiesysteem nivelleert de directe effecten van mentale inspanning en maakt daarmee de interpretatie van de werklast-effecten op de cardiovasculaire maten moeilijker. Dit geldt met name voor de hartslag en hartslagvariabiliteit. Door onderscheid te maken tussen effecten die direct gerelateerd zijn aan de taakeisen en effecten die veroorzaakt worden door het bloeddruk regulatiesysteem, krijgen we meer zicht op de echte taakgerelateerde mentale inspanning. Dit heeft geleid tot de ontwikkeling van betere mentale werklast-maten die bruikbaar zijn bij adaptieve automatisering