Alongside new cancer treatments come common side effects or conditions that may pop up, such as lymphedema. The lymphatic system doesn’t get much attention until it stops working properly. As many breast cancer patients have learned, the lymph nodes that reside in your armpits are essential for draining fluid from your arms. If these lymph nodes are damaged during medical treatment or removed to prevent the spread of cancer, fluid can accumulate and lead to painful swelling in one or both arms.
But now, a research group from the University of Waterloo in Canada has used microfluidics to develop a major improvement in lymphedema treatment, as reported in the journal Microfluidics.
Emerging Medical Technologies Treat Lymphedema
Lymphedema affects roughly 30% of women who are treated for breast cancer, according to a report in the Journal of Clinical Oncology. Standard treatment for lymphedema includes massaging the affected limb — using a squeezing and dragging motion — to push fluid from the extremities (e.g. fingers) toward the torso (e.g. shoulder). This is often followed by wearing a compression sleeve to prevent additional swelling. One advantage of a compression sleeve is that it can easily be worn for long periods of time without interfering with daily activities.
In contrast, the massage technique for treating lymphedema is labor-intensive and difficult to perform on oneself. You can achieve the same general effect with an intermittent pneumatic compression (IPC) device. This device is somewhat similar to the blood pressure cuff fastened around a patient’s arm at the beginning of nearly every doctor’s visit. The blood pressure cuff is an air bladder that fills with air up to a certain pressure, then deflates. For an IPC device, the patient wears a long sleeve that contains perhaps 16 air bladders lined up in a row. The air bladder around the hand inflates first, followed by the air bladder around the wrist, and so on until all the air bladders have inflated to push fluid from the hand toward the shoulder. The air bladders then deflate, and the process is repeated.
The problem with existing IPC devices is that they can be bulky, heavy and expensive (some are more than $1000), and need to be plugged into a wall. This is far from ideal for the many patients who need extensive therapy. More portable systems are available at a lower price (around $300), but are less effective. These more affordable systems use electromechanical solenoid valves to control the air bladders. The most effective systems have many air bladders — which require many solenoid valves — which means more expense, more weight and more energy consumption.
Microfluidics Shrink the Problem
The researchers at the University of Waterloo sought to develop a more effective, affordable and portable pneumatic compression sleeve. The key was to replace the solenoid valves with a microfluidic chip. The chip was created with 3D printing technology, and the “fluid” is air. Each microfluidic chip has 16 fluid channels, or tubes of specific diameters, that control eight air bladders. Each air bladder has a channel that controls inflation and a channel that controls deflation.
The inflation channels vary in cross-sectional area from 0.04 mm2 to 1 mm2, which controls how quickly each bladder fills with air. All the deflation channels are the same size, so deflation is simultaneous. The microfluidic chip has no moving parts, and requires just two miniature solenoid valves — one for the inflation channels and one for the deflation channels. The small size means that the device can be run on a 3.7-volt lithium-ion battery, and the entire control unit weighs less than a typical smart phone.
The compression sleeve prototype included 8 air bladders, and was tested on a 3D printed forearm. The testing team placed a sensor between the sleeve and a mock forearm. From there, they measured and optimized the pressure to encourage fluid movement. The researchers intend to develop a commercially viable product, and are moving toward patient testing. The microfluidic chip can be scaled up to control 16 air bladders, which would produce a full-arm sleeve similar to what is commercially available for plug-in IPC devices. Because of the small, inexpensive components, the device would likely cost hundreds of dollars instead of thousands.
Major Improvement to Therapy
This effective and portable pneumatic sleeve isn’t quite a new cancer treatment, but it is a significant contribution to the emerging medical technologies that are rapidly improving patient treatment and quality of life. According to StatPearls, lymphedema affects about 1 in 1,000 Americans. While the most common cause is breast cancer treatment, lymphedema in the arms or legs can be caused by infection, trauma, radiation and other medical treatments.
The underlying design of the microfluidic chip can be extended to other applications. Most obvious would be compression sleeves for lymphedema in the legs, but another possibility is prosthetics for lower leg amputees. Legs naturally swell and shrink during daily activities, which causes discomfort and friction for amputees wearing prosthetics. A balloon system could inflate or deflate on demand, making prosthetics more comfortable to wear.
