Saving lives every day

Imagine being unable to breathe … During the coronavirus pandemic that fear was realised for unprecedented numbers of people. Ventilators – another Swedish innovation – played a crucial role in saving lives.

People suffered breathing difficulties during previous epidemics as well. When a polio epidemic broke out in the late 1940s, the main treatment available was the iron lung. It resembled a large tin can that enclosed the patient’s entire body, with just their head sticking out through a rubber collar. The iron lung worked by alternating high and low pressure around the patient’s body, helping them to inhale and exhale. Even so, many patients died.

When Carl Gunnar Engström qualified as a doctor in 1941, he took up a post to treat infectious diseases at Stockholm’s isolation hospital. If he had contented himself with that role, the modern ventilator would never have come about. Fortunately, Engström took on an extra job with the Swedish Air Force, examining test pilots who flew near the sound barrier.

Supersonic flight was in its infancy in the late 1940s. Saab, the Swedish engineering and manufacturing company, had started developing a fighter plane that could reach such speeds. A Saab 32 Lansen exceeded the sound barrier for the first time in 1953.

Engström was interested in the effects of such extreme forces on the levels of various gases in pilots’ blood, so he conducted a series of tests.

Engström quickly noticed a similarity between his patients and the supersonic pilots. Too much carbon dioxide remained in the patients’ blood. Because it was not possible to check how much air patients were getting inside the iron lung, doctors could not monitor their oxygen and carbon dioxide levels. Engström developed an air pump that could regulate the air in a patient’s lungs by means of an airtight tube in their trachea. In July 1950, his first prototype was ready. The first volume-controlled artificial ventilator went into production the following year. In addition to helping many polio patients, the device was of great benefit in operating theatres.

In 1963, Carl Gunnar Engström received his PhD on the basis of his invention. Further improvements were made as the device spread round the world.

The original Engström ventilator was large and bulky, but it represented a revolution in healthcare by pumping air into patients’ lungs. It was widely used in a polio epidemic in the 1950s.

The crucial breakthrough is credited to a Swedish medical student, Björn Jonson, who in turn got the idea for a flow regulator from his lecturer Sven Ingelstedt in 1964. Ingelstedt kept a collection of unsolved problems in a folder labelled ‘Only God and I know’. Ingelstedt’s self-confidence was as great as his generosity towards others. He had dismissed earlier attempts to create a functional flow regulator, saying, ‘You cannot regulate the flow’. But when Björn Jonson, who had also identified the issue of regulating the timing and rate at which air was delivered to patients, asked, ‘If I figure out how to regulate it, can we build a ventilator?’ Ingelstedt was quick to reply, ‘Absolutely!’

That was the first step along the path to the modern ventilators we have today. The problem was that Jonson had no access to a laboratory and no knowledge of how to build medical equipment. But he knew where he could get help. Soon he made friends with skilled technicians at the hospital in Lund. They helped him to grind, polish and drill glass and metal components. When Jonson nearly caused a disaster in the hospital’s workshop, he was banned from the facility. Then Håkan Westling, professor of clinical physiology, purchased a lathe and a milling machine, which they set up in a broom cupboard, under the hospital management’s radar. Jonson used the equipment to assemble some functioning flow regulators. Working with Sven Gunnar Olsson, an engineer, he also constructed a new type of ventilator. It was silent and weighed just 4 kilograms (8.8 lb), a fraction of Engström’s bulky model. Crucially, it was far more versatile. It allowed patients some control over their breathing. Björn Jonson applied for a patent on his ventilator. The following day, he headed to Elema-Schönander, a medical technology company that would later be acquired by Siemens.

The company invested significant resources in the device and gave Jonson and Olsson, working with anaesthetist Lars Nordström, the freedom to continue refining their ideas. Their new ventilator featured electronic flow and pressure gauges, and they soon added a carbon dioxide gauge. As a physiologist, Jonson knew that the diagnostics was as important as providing air flow to the patient. When their ServoVentilator was launched 1971, it quickly became a global leader. Updated versions are still manufactured by Getinge today.

The modern ServoVentilator functions as both breathing support and diagnostic instrument. When it was launched in 1971, it formed the basis of intensive care, an entirely new concept at the time.