Today, intensive care units (ICUs) and mechanical ventilators provide life-saving medical care when it matters most. ICUs treat some of the sickest patients — those with severe infections, heart and respiratory failure, brain injuries and other life-threatening conditions. While the COVID-19 pandemic brought the work of critical care into the forefront, another public health emergency was the impetus behind it.
In her new book The Autumn Ghost, Sunnybrook critical care physician and researcher Dr. Hannah Wunsch describes how the polio epidemic of 1952 led to the invention of new technology — including the ventilator — that would revolutionize medical care.
In this Q & A, Dr. Wunsch discusses polio and the origin story of intensive care.
Prior to the invention of the ventilator, how were patients with life-threatening respiratory disease managed?
Dr. Wunsch: For the most part, people would have been provided with supplemental oxygen, either through a mask or a ‘tent’. Beyond that there was little that could be done for people, and so the focus was primarily on ensuring comfort, using medications such as morphine. The death rate from respiratory illnesses was therefore very high. The one exception to this was polio.
What is the iron lung and how was it used to treat patients with polio?
Dr. Wunsch: For patients with a certain type of polio that impacted the muscles used for breathing, there was a device called the iron lung. This sealed a person’s body into a tube of metal and then created negative pressure in the tube which forced the lungs open and caused air to rush in through the mouth and into the lungs. This ‘negative pressure ventilation’ was quite effective to support breathing when it was just these muscles that were impacted. But the iron lung was pretty much useless for most other types of respiratory illness, and also for the most severe form of polio, called bulbar polio, which affected the muscles that control functions like swallowing.
Why is polio described as the epidemic that invented intensive care?
Dr. Wunsch: Polio forced a lot of innovation and many of the concepts that are part of modern ICUs came from the need to provide better, safer care to polio patients. First, in 1928, was the invention of the iron lung, which was the beginning of the concept of machines that can provide organ support. However, the events in one polio epidemic in 1952, in Copenhagen, forced further innovation. They had only one iron lung, and many of their patients had bulbar polio. This led to the decision to try positive pressure ventilation using a tracheostomy (a tube inserted through the neck into the trachea) and then to blow air into the lungs. This approach was then used on hundreds of patients and was shown to be effective for supporting people with respiratory failure. Modern mechanical ventilation, with a temporary endotracheal tube through the mouth into the trachea, comes directly from this experience. Along with the actual intervention, there was a lot of recognition that you needed very skilled nurses, doctors and other healthcare team members to safely take care of these people.
Another important concept that came out of the same epidemic was ‘blood gas analysis.’ This is now a mainstay of critical care — the idea of measuring the pH of a person’s blood and the amount of carbon dioxide (as well as oxygen) in it to help guide ventilation.
How have more recent public health emergencies, like COVID-19, impacted critical care?
Dr. Wunsch: Critical care has always operated in what I think of as the shadows of medicine, but COVID-19 made the public more aware of the specialty. The importance of care in ICUs really wasn’t appreciated by most people because it’s not a specialty that people routinely interact with (unless they or someone they know gets extremely ill). COVID-19 also showed us the limitations of critical care – we could not save everyone, even with our most high-tech cutting-edge machinery. And, it showed us the limits of our providers — it was such a strain on everyone for so long that there is real concern about burnout, especially among skilled critical care nurses.
On a more positive note, COVID really brought the world’s critical care community together. There is a real sense of closeness in the global community of critical care providers, and the exchange of information has accelerated, leading to advancements in patient care.