How to maintain lithium batteries in medical devices (such as pacemakers)?

Lithium batteries in medical devices are the "invisible guardians" that maintain life - pacemakers rely on them to keep beating, portable ventilators rely on them to maintain oxygen supply, and insulin pumps use them to accurately control the amount of medicine. However, the maintenance of these batteries is far more complicated than that of mobile phones or laptops, and the slightest carelessness may endanger the patient's life. This article will deeply analyze the particularity of lithium batteries in medical devices and provide scientific maintenance methods to help patients and medical staff extend the life of the equipment and ensure safety.

I. The particularity of lithium batteries in medical devices

1. Implantable devices vs. external devices

• Implantable devices (such as pacemakers):

1. Battery type: Mostly lithium-iodine (Li-I₂) batteries, with high energy density and low self-discharge rate (annual self-discharge <1%).
2. Lifespan: Usually 7-15 years, cannot be recharged or replaced, and surgery is required to replace the device.
3. Core requirements: absolute reliability, and early warning replacement must be ensured before the battery is exhausted.

• External devices (such as portable monitors, infusion pumps):

1. Battery type: lithium ion or lithium polymer battery, rechargeable.
2. Lifespan: 3-5 years, requires regular maintenance.

2. Strict safety standards

• Implantable batteries: Pass ISO 13485 medical device quality management system certification, and must withstand long-term stable operation at body temperature (37°C).
• External device batteries: Comply with IEC 60601 medical electrical equipment safety standards, leak-proof and short-circuit-proof design.

 

II. Maintenance of lithium batteries for implantable medical devices (taking pacemakers as an example)

1. Daily precautions for patients

• Avoid strong electromagnetic fields:

1. Stay away from magnetic resonance imaging (MRI) equipment (unless the equipment is marked "MRI compatible").
2. Keep a distance of more than 15 cm from the phone to avoid interference (refer to the American Heart Association's recommendations).

• Regular remote monitoring:

1. Automatically upload data through a home monitoring system (such as Medtronic CareLink), and doctors can remotely view the battery remaining.
2. Warning signal: If the device beeps or the heart rate is abnormal, you need to seek medical attention immediately.

• Do not operate on your own:

1. Do not attempt to charge the implanted battery with an external charger (this function does not exist).

2. Professional maintenance by medical staff

• Battery life prediction:

Use a programmable instrument to read the battery voltage and impedance and calculate the remaining life (such as Boston Scientific's "Elective Replacement Indicator").

• Replacement time:

When the battery capacity drops to 10%-20% (about 3-6 months of life left), surgery needs to be arranged for replacement.

 

III. Maintenance of lithium batteries for external medical devices (taking portable ventilators as an example)

1. Charging management

• Shallow charging and shallow discharge:

Charge when the power drops to 20%, and stop when it reaches 90% (avoid long-term full charge).

Case: Philips ventilators recommend "charging as you use" and fully charging and discharging to calibrate the fuel gauge once a month.

• Use the original charger:

Poor quality chargers may cause overcharging and damage the battery (e.g. ResMed AirSense 10 explicitly requires the original power adapter).

2. Storage and environmental control

• Long-term storage:

Charge to 50%, disconnect the device, and store in a dry environment below 25°C.

Recharge to 50% every 3 months.

• Avoid extreme temperatures:

High temperature (>40°C) accelerates aging, and low temperature (<0°C) causes a sudden drop in capacity (e.g. Dräger ventilator battery loses 50% capacity at -20°C).

3. Safe cleaning

Direct contact with liquids is prohibited: wipe the battery contacts with 75% alcohol cotton pads to avoid penetration into the interior.

 

IV. Common misunderstandings and risk warnings

1. Clarification of misunderstandings

• ❌ "Implanted batteries can be charged wirelessly"

Truth: Currently there are only experimental technologies (such as MIT's in vivo wireless charging), which have not yet been clinically applied.

• ❌ "Shutting down the device can extend the battery life"

Truth: Implanted devices such as pacemakers need to run 24 hours a day, and shutting down is equivalent to stopping treatment.

2. Dangerous operations

• Disassembling external batteries by yourself: may cause leakage or short circuit (such as damaged seal of insulin pump battery compartment).
• Mixing old and new batteries: Mixing old and new batteries of external devices can easily lead to over-discharge (such as uneven voltage of defibrillator batteries).

 

V. Future technology: safer and more durable medical batteries

1. Solid-state lithium batteries:

No risk of leakage, life extended to 20 years (such as QuantumScape and Medtronic's joint research and development).

2. Biodegradable batteries:

Short-term implanted devices (such as postoperative monitoring sensors) naturally degrade after use, avoiding secondary surgery.

3. Energy harvesting technology:

Use human movement or body temperature to generate electricity, reducing dependence on traditional batteries (such as pacemaker + piezoelectric material experiments).

 

Conclusion: Life is priceless, details determine safety

Maintenance of lithium batteries in medical equipment is a combination of science and responsibility. For patients, regular monitoring and avoiding risky environments are key; for medical staff, accurately predicting battery life and replacing them in time are their responsibilities. With technological advances, medical batteries will be smarter and more reliable in the future, but the attitude of respecting life and rigorous maintenance will never change.