Medical engineering has made many great gains. From simple devices such as syringes to state-of-the-art technology such as surgical robots and CT scanners, the products save lives. But the development of medical devices is often focused on solving the health problems of people who live in developed countries.
People in developing countries see little of these life-changing advances as many devices are too expensive and do not meet the health needs of local people. A staggering 75% of all medical devices in the developing world’s clinics and hospitals lie unused, according to the World Health Organisation. Many of these devices have been donated from the West with little consideration of the local expertise and health priorities.
Dr Patrick Finlay, vice-chairman of the IMechE’s medical division, says: “Health clinics in the world’s poorest countries have no choice but to turn to these Western medical technologies simply because there are so few devices that have been designed specifically for them.”
In some instances the technology cannot function in a low-income setting: a dialysis machine is no use without mains electricity for example. In other cases the devices can bring no health benefits to local people. One African hospital received a donation of several pulse oximeter machines which measure the oxygen saturation of a patient’s blood through their fingertip. The devices remained worthless because medics had no oxygen to give the patients if readings were low.
Often there is no local expertise to maintain and repair medical devices, and spare parts are expensive or impossible to get hold of. Professor Chris Lavy, of Oxford University, who has worked extensively in sub-Saharan Africa, explains that one of the newest hospitals on the continent has been built with infrared sensors to control the operating theatres’ taps even though there is no one with the ability to fix them. “Within a year most of them had failed, some in the off position and some in the on position,” he says.
But there is a small group of engineers who are rising to the challenge of creating affordable and relevant medical technology that will benefit people living in low-income countries. We take a look at some of their promising ideas.
Motorbike ambulance reaches the remotest places
The eRanger ambulance is designed for hard-to-reach areas to provide transport to and from clinics. It is a motorbike with a sidecar stretcher that can carry a patient, medical worker and emergency supplies. It costs one eighth of the price of a conventional 4x4 ambulance and is the brainchild of Mike Norman, a former motorcycle designer.
Norman took an agricultural motorbike and replaced the front suspension with shock absorbers. He explains: “This type of suspension is more appropriate for a sidecar. You can steer it with just two fingers even on rough terrain – it is very light.” He also fitted heavy-duty tyres, beefed-up the axles and lowered the gearing, so the bike has lower torque. The bikes are engineered for minimum maintenance and downtime, and have been destruction-tested, adds Norman. The eRanger is made in South Africa in left- and right-hand drive versions. It is used in 18 developing countries, with Guinea and Tanzania the latest to place orders.
In 2004-05 the Malawi ministry of health sent 10 bikes to Dowa district and saw the maternal death rate fall 60% in two years, says Norman.
A new project in Haiti will see the bikes rolled out there, and eRanger is working towards setting-up an assembly plant in the country, as part of the reconstruction effort after the 2010 earthquake. The company is also in talks with the Gates Foundation, which is interested in taking the ambulances to South America and India. Norman says: “We can’t turn them out quick enough.”
Solar-powered hearing aid
In the developing world, fewer than one in 40 people who need a hearing aid have one. Where hearing aids are available they are generally expensive and inappropriate, says the World Health Organisation. This is because developing countries rely on hearing aids donated from the West. These devices usually sit on the outside of the ear to amplify sounds. They are ideal for age-related hearing loss, common in wealthy countries, but are much less effective for problems caused by an infection that has damaged the ear drum. Infections are the prevalent cause of hearing loss in low-income countries.
Taking inspiration from bone conduction technology that has existed since the 1930s, Andrew Carr came up with the idea of a hearing aid suitable for the developing world during his final-year project at university. The device, known as Hearware, sits on a bone at the back of the head and sends vibrations through the skull to the inner ear, bypassing the parts of the ear that have been damaged by infection.
Conventional hearing aids use micro batteries that are almost impossible to find in sub-Saharan Africa, so Hearware uses solar power. “There are 10 photodiodes put in reverse bias on the outside of the device,” explains Carr, who now works as a mechanical engineer at Plexus. “With some simple filtering and circuitry they will recharge an internal battery.”
The outer shell of the Hearware device can be changed with snap-on cases, which means that local people can tailor the appearance of the device to make it culturally acceptable. “The manufacturing cost of one of these is around $20,” says Carr.
The project is still at the design stage, but the technology has been proven with off-the-shelf components, he adds.
Heart monitor
Almost half of Africa’s population now have mobile phones and according to engineer Dr Thomas Brennan the mobile platform will be the future of appropriate health technology on the continent. “Mobile phones are going to become more ubiquitous and people will use them for more things,” he says.
He goes on: “All you need is a sensor measuring some aspect of a patient’s body. You can process the information in the cloud so that the handset that remains in the person’s hands stays relatively cheap.”
In his latest project, the sensor is an egg cup attached to the microphone of a hands-free kit on the basic Nokia 3110 mobile phone. A rubber O-ring sits in the rim of the egg cup to create a seal and the device can be placed on a patient’s chest to make recordings of the heart. These recordings can then be sent from the phone to a server that applies algorithms to the data and flags up patients at risk. Health workers, who may be many miles away from the patients, can then advise them to seek help.
The idea came about after Brennan heard a cardiologist complaining that his patients with tuberculous pericarditis were dying. “They were going home and he had no idea what was happening to them – they weren’t coming back for check-ups,” says Brennan. Around 40% of patients with pericarditis – inflammation of the sac that surrounds the heart – caused by tuberculosis infection die suddenly after diagnosis because they can’t get to the clinic before it’s too late.
Death can be prevented by monitoring heart sounds using a heart monitor. But for many people living in rural areas getting to the clinic for check-ups can be difficult and may involve walking for miles. The mobile stethoscope enables cardiologists to keep tabs on their patients remotely. It has been tested in a clinical trial involving 150 patients in South Africa.
Preventing HIV infection
An adapted nipple shield that one day may deliver antiretroviral drugs to breast-feeding babies to stop them contracting HIV from infected mothers is being developed at Cambridge University. Around 200,000 babies become infected with HIV every year through breast feeding, which accounts for 40% of all mother-to-child transmission of the virus.
Currently, nurses inject babies that are breast-fed by HIV-positive women with a syrup containing prophylactic drugs in an attempt to protect them from the virus. Compared to tablets, syrups are expensive, bulky and need to be refrigerated, which is not always possible in low-income countries. In order for anti-HIV mother-to-child initiatives to reach all those who need them, the medication needs to be inexpensive, easy to distribute and to have a long shelf life.
“There is some evidence that the funding for HIV programmes is flat-lining, so we have to do more with the same amount of money,” says Aaron Rodrigues, president of Engineering World Health in Cambridge, who is working on the project.
To address these needs, the Just Milk team is developing an antiretroviral tablet that can fit inside a specially modified nipple shield and dissolve into the mother’s breast milk. Prototypes of the shield are made of silicone and contain a lip on the inside of the tip to keep the tablet in place. The team is now working on the parameters of the tablet, before clinical trials assess the efficacy of the method of delivery and the drug itself, as well as the safety and suitability of the concept. Rodrigues explains: “The aim is for mothers to only need to use the shield once a day.” Mothers in the West reuse nipple shields by boiling and sterilising them, but this may be impractical in many homes in low-income countries.
To get around this the team is looking at how to lower the cost of manufacturing the device. “We are trying to reduce the cost to the point where nipple shields will be competitive with syringes. As a disposable platform that would be ideal,” says Rodrigues.