Flexible, wearable oral sodium sensor could help improve hypertension control


Summary:
For people who have hypertension and certain other conditions, eating too much salt raises blood pressure and increases the likelihood of heart complications. To help monitor salt intake, researchers have developed a flexible and stretchable wireless sensing system designed to be comfortably worn in the mouth to measure the amount of sodium a person consumes.

For people who have hypertension and certain other conditions, eating too much salt raises blood pressure and increases the likelihood of heart complications. To help monitor salt intake, researchers have developed a flexible and stretchable wireless sensing system designed to be comfortably worn in the mouth to measure the amount of sodium a person consumes.

Based on an ultrathin, breathable elastomeric membrane, the sensor integrates with a miniaturized flexible electronic system that uses Bluetooth technology to wirelessly report the sodium consumption to a smartphone or tablet. The researchers plan to further miniaturize the system — which now resembles a dental retainer — to the size of a tooth.

“We can unobtrusively and wirelessly measure the amount of sodium that people are taking in over time,” explained Woon-Hong Yeo, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “By monitoring sodium in real-time, the device could one day help people who need to restrict sodium intake learn to change their eating habits and diet.”

Details of the device are reported May 7 in the early edition of the journal Proceedings of the National Academy of Sciences. The device has been tested in three adult study participants who wore the sensor system for up to a week while eating both solid and liquid foods including vegetable juice, chicken soup and potato chips.

According to the American Heart Association, Americans on average eat more than 3,400 milligrams of sodium each day, far more than the limit of 1,500 milligrams per day it recommends. The association surveyed a thousand adults and found that “one-third couldn’t estimate how much sodium they ate, and another 54 percent thought they were eating less than 2,000 milligrams of sodium a day.”

The new sodium sensing system could address that challenge by helping users better track how much salt they consume, Yeo said. “Our device could have applications for many different goals involving eating behavior for diet management or therapeutics,” he added.

Key to development of the intraoral sensor was replacement of traditional plastic and metal-based electronics with biocompatible and ultrathin components connected using mesh circuitry. Sodium sensors are available commercially, but Yeo and his collaborators developed a flexible micro-membrane version to be integrated with the miniaturized hybrid circuitry.

“The entire sensing and electronics package was conformally integrated onto a soft material that users can tolerate,” Yeo explained. “The sensor is comfortable to wear, and data from it can be transmitted to a smartphone or tablet. Eventually the information could go a doctor or other medical professional for remote monitoring.”

The flexible design began with computer modeling to optimize the mechanical properties of the device for use in the curved and soft oral cavity. The researchers then used their model to design the actual nanomembrane circuitry and choose components.

The device can monitor sodium intake in real-time, and record daily amounts. Using an app, the system could advise users planning meals how much of their daily salt allocation they had already consumed. The device can communicate with a smartphone up to ten meters away.

Next steps for the sodium sensor are to further miniaturize the device, and test it with users who have the medical conditions to address: hypertension, obesity or diabetes.

The researchers would like to do away with the small battery, which must be recharged daily to keep the sensor in operation. One option would be to power the device inductively, which would replace the battery and complex circuit with a coil that could obtain power from a transmitter outside the mouth.

The project grew out of a long-term goal of producing an artificial taste system that can sense sweetness, bitterness, pH and saltiness. That work began at Virginia Commonwealth University, where Yeo was an assistant professor before joining Georgia Tech.

Journal Reference:

  1. Yongkuk Lee et al. Wireless, Intraoral Hybrid Electronics for Real-Time Quantification of Sodium Intake Toward Hypertension Management. Proceedings of the National Academy of Sciences, 2018 DOI: 10.1073/pnas.1719573115
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Renal function and sodium intake: A review. 


Recent guidelines propose a dietary sodium intake of less than 2.0 g or even less than 1.5 g daily for patients with chronic kidney disease (CKD), report Japanese nephrologists at the Teikyo University School of Medicine in Tokyo. However, other topical studies have failed to find robust evidence to support this approach and have even indicated that a sodium intake of less than 1.5 g/d could be potentially harmful. In view of the ongoing controversy, the aim of the present quantitative review of the literature was to assess currently available evidence. Data were extracted from 36 studies (11 cross-sectional and 5 longitudinal observational studies, 20 intervention trials).
The key findings:
  • In observational studies, renal function as assessed by eGFR, albuminuria, urinary albumin-to-creatinine ratio, CKD, or ESRD yielded insufficient direct evidence for association with sodium intake.
  • Five longitudinal studies did not generate robust evidence that reduction of salt intake would prevent CKD or its progression.
  • The majority of intervention studies failed to provide sufficient information on design, results, and potential sources of bias, resulting in low quality scores.
  • According to intervention studies, eGFR and albuminuria or proteinuria increased with higher salt intake.
This review shows that there is currently no robust evidence to suggest that a long-term reduction of salt intake could or would prevent CKD or delay its progression, summarize the authors. However, they also stress that the present review is mainly based on studies investigating people with only low-grade renal impairment. Therefore, the current findings cannot be extrapolated to patients with moderate or severe chronic kidney disease.

Does Sodium Intake Affect Mortality and CV Event Risk?


Sodium intake may not be associated with mortality or incident cardiovascular events in older adults, according to a study published Jan. 19 in the JAMA: Internal Medicine.

In the Health, Aging and Body Composition (Health ABC) Study, initiated in 1997, researchers assessed self-reported sodium intake from 2,642 Medicare beneficiaries, ages 71-80 years old. Participants were excluded for difficulties with walking or activities of daily life, cognitive impairment, inability to communicate, and previous heart failure (HF). At the first annual follow-up visit, researchers recorded food intake as reported by participants, specifically examining sodium intake. After 10 years, 34 percent of patients had died, while 29 percent and 15 percent had developed cardiovascular disease and HF, respectively.

The results of the study showed that there was no association between participant-reported sodium intake and 10-year mortality, incident HF or incident cardiovascular disease. Further, there was no indication that consuming less than 1,500 mg/d of sodium benefitted participants any more than consuming the recommended amount (1,500-2,300 mg/d). However, the study showed a slight potential for harm when participants had a sodium intake of greater than 2,300 mg/d, especially in women and African Americans.

The authors note that while the food frequency questionnaire used by participants at the first annual follow-up has limitations in its accuracy, “self-reported adoption of a low-salt diet was not associated with significantly higher risk for [any] events.” They conclude that moving forward, there is a need for further research and stronger evidence in order to create better recommendations for older adults.

– See more at: http://www.acc.org/latest-in-cardiology/articles/2015/01/16/15/47/does-sodium-intake-affect-mortality-and-cv-event-risk-acc-news-story?wt.mc_id=fb#sthash.vE0R3iGF.dpuf