Designing safe, compliant medical devices

Designing a product for a medical application is probably one of the biggest challenges for a design engineer because of the confusing jungle of standards and guidelines. This article covers some of the most important aspects of designing a safe and compliant medical product that Escatec has learned during the process of becoming one of the few contract design and manufacturing companies to have achieved certification to the ISO standard for medical equipment – ISO 13485.

Medical and technical advances are closely inter-related. New technologies allow greater levels of detailed information about the health of a patient to be obtained and thus open up new therapeutic treatment options.

This progress leads to a steady increase of medical technology being applied on patients placing a responsibility on the manufacturer of medical products to ensure that products are extensively tested for technical security and reliability as lives depend on them.

Furthermore, the risk-benefit ratio has to be constantly assessed during the development. Extensive verification and validation processes accompany the approval procedure.

An example of a medical product designed and manufactured by Escatec is the Twinstream multi-mode respirator for Carl Reiner GmbH – see Figure 1. The challenge was how to design a ventilator for use when performing an operation on a patient’s throat where the normal techniques of a pipe inserted into the throat would block access to the area being operated upon.


Essentially the problem was how to pump air in and out of the lungs in an open system. It is rather like inflating and deflating balloon with a tube into the balloon open all the time through which instruments and lasers can move.

The Twinstream multi-mode respirator actually has two ventilators that operate completely independently with different frequencies and different pressures. The first provides the conventional 12 or so breaths per minute whilst the second provides a high frequency of around 800 breaths per minute. This second, high frequency ventilation reduces the stress on the lungs during lengthy operations that can take many hours, because it is very efficient at moving air in and out. This ensures that CO₂ is removed more easily, and oxygen reaches deep into the lungs to be more effectively absorbed into the bloodstream.