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Hearing aid battery compartments need locks

Key points

  • Swallowing a button battery, such as those used in hearing aids, is a medical emergency. However, the seriousness of the situation is not always understood. Problems can appear several days or weeks after they are swallowed, and in younger children the ingestion may not be witnessed.
  • Battery compartments in hearing aids should be tamper-proof to prevent them being swallowed accidentally, or a child choking on them. Greater awareness is also needed of the risk.
  • Hearing aid designers need input from audiologists, gastroenterologists, paediatric staff as well as parents and patients.

Background
CHI+MED researcher, Chitra Acharya, has a young son (Avy) who has complex learning needs and who uses a hearing aid. During a routine clinic visit his mother spotted that he had taken out his hearing aid and put it in his mouth, unfortunately the battery was missing. As they couldn't find the battery in his buggy or clothing the nurse advised going straight to accident and emergency for an X-ray. Fortunately the scan was clear though the doctor outlined the risks from swallowing batteries, in addition to their choking risk. She recommended raising the issue with hearing aid manufacturers. Because of her position on CHI+MED, Chitra investigated the issue in depth. Even flat batteries can create an electrical current that leads to a build-up of sodium hydroxide (caustic soda). This causes serious tissue damage that can continue even after the battery has been removed. This problem has resulted in life-changing injuries and death.

While the audiologist was later able to add a lock to the battery compartment this simple solution should be widespread and standard - all hearing aids should have tamper-proof locks fitted automatically. No amount of parental training can prevent accidental ingestion as efficiently as a lock and constant vigilance is impractical.

Recommendations
The CHI+MED team investigated the issue further and based on this case developed a series of recommendations. Awareness of the risks and their seriousness is needed among many stakeholders.

  • Parents, carers and healthcare staff need to know that battery ingestion is a medical emergency and that follow-up care may be needed for several weeks. Unexplained symptoms of coughing up or vomiting blood and respiratory difficulties may indicate battery ingestion (perhaps unwitnessed).
  • Mistaken beliefs about battery ingestion needs to be challenged: some healthcare professionals have considered that "battery ingestion would be harmless unless the battery was damaged or leaking" (NHS England 2014) however it is the electrolytic effects that can cause catastrophic damage.
  • Near-miss incidents with batteries need to be systematically recorded with an opportunity to learn from these and share learning across departments (audiology, gastroenterology, A&E) as well as with manufacturers.
  • Information needs to be communicated, by parents and healthcare professionals, to hearing aid designers so that they can 'design out' this risk by fitting locks.
  • Regulators need to incentivise marketing of products which have tamper-proof battery locks.

Chitra and colleagues have raised awareness of the issues including publishing an article in the British Academy of Audiology's journal discussing the problem and its simple solution. Her story has also appeared in the NDCS (National Deaf Children's Society) magazine 'Families' and in IRIS magazine for carers. She has also given a series of talks to further raise awareness. In addition to locks for battery compartments researchers at MIT, Brigham and Women's Hospital, and Massachusetts General Hospital are now investigating a pressure-sensitive battery coating which allows electrical conduction only when the battery is compressed in a battery housing (MIT 2014).

In parallel NHS England published a Patient Safety Alert in December 2014 which was well-timed for the Christmas season in recognition of the particular risks with new battery-operated Christmas presents. An analysis of incident reports found 241 cases of battery ingestion with 5 cases of severe tissue damage. One child died from complications that arose after they had been discharged.

Key people
Chitra Acharya, Alexis Lewis, Harold Thimbleby

References
NHS England (19 December 2014) Stage One: Warning Risk of death and serious harm from delays in recognising and treating ingestion of button batteries

Acharya, C, Manchaiah, VKC, Lewis, A and Thimbleby H (2015) Hearing aid battery ingestion: medical error or poor design

The IRIS magazine (March 2015) Vigilant parent helps spread hearing aid safety awareness, p13

NDCS Families (Spring 2015) Winning the battle of the hearing aids!, p18

MIT News (2014) New way to make batteries safer

Further reading
Reducing harm from button batteries (2016) CHI+MED blog

What should I do if I think my child has swallowed a button battery? Leicester Safeguarding Children Board