There was a time, back in the 1840’s, when handwashing wasn’t a thing yet. Mothers in Vienna would buy baby clothes in great anticipation of their child’s arrival, and would go to the Maternity Hospital for delivery. What they didn’t know is that one of its two wards had a very big problem. Physicians there were loosing a mother or newborn every other day on average.
Puerperal fever, a kind of infection of the birth canal, took a thousand one lives over the course of 5 years, above and beyond the much better situation in the second ward.
Dr Ignaz Semmelweis, the obstetrician in charge of the two wards, was part of the emerging culture of physician scientists that used data to influence medical practice. So he went to work on the puzzle.
As Louis Pasteur the French microbiologist remarked a few years later, "In the field of observation, chance favors only the prepared mind." Dr Semmelweis discovered that aseptic handwashing techniques prevent infection.
Hacking the Sepsis
Dr Semmelweis wrote a detailed account of how he arrived at his aseptic technique. What he put together by observation and reflection was truly mindblowing. Here are 6 of the puzzle pieces:
- The death of a colleague by infection from an autopsy puncture wound, similar in pathology to what he saw happening in the wards;
- A historical review showing comparatively low rates of puerperal fever in both wards for many years prior to the spike in Ward 1;
- The shift to anatomic study in the medical schools of Vienna, so that physicians attending Ward 1 had frequent contact with cadavers;
- Scheduling autopsies just before deliveries in Ward 1;
- The observation by smell that Ward 1 physician’s hands were not clean after autopsies, despite handwashing with soap and water;
- Staffing of Ward 2 with only midwives, who did not perform autopsy work.
Little by little, the competing arguments were peeled away to reveal the infection pathway idea (contamination by material from the autopsies). Dr Semmelweis hit gold over the course of 1847 through 1848, when he experimented with chlorinated lime as a handwashing agent and requirement for labor and delivery procedures.
Visualizing the Data
Dr Semmelweis published his work with lots of data tables, but without any visuals. Data combined with visuals and stories help inspire. For the example visualization below, I had to stitch data across multiple tables, but it was a relatively easy exercise.
This is a horizontal stack chart of puerperal fatalities by year. Each year is represented by one bar stacked with the blue Ward 2 number, then gray showing the same number for Ward 1 (as if it were equal to Ward 2), and finally the red Ward 1 number of events above Ward 2 (the difference of the two wards).
The vanishing of the red is a direct result of Dr Semmelweis’ implementation of chlorinated lime handwash in both wards (partial year 1847 and full year 1848). Ward 1 was then brought in line with Ward 2. In 1848 he saved 200 lives, about the average difference between the wards over the previous 5 years. Over 5 years, that's 1001 lives.
“Once the chlorine washings were adopted and the patients were examined only by persons with clean hands, patients with extended periods of dilation stopped dying, and extended labor was no more dangerous than in the second clinic.” Dr Semmelweis
The average annual number of births in both wards was statistically about the same over the time range of this chart (about 3250 births), so the stack chart numbers can be compared properly. This was confirmed on my mobile phone with a text message request for Passplot’s automated t-test workflow. The difference of the two wards (the red bar values) was confirmed for Bell-likeness using a normality test request to Passplot. Bell curves are nice to work with.
Finally, the horizontal stack chart was also made with Passplot, using a third text message, the overall analysis including the stats checks above taking less than a minute.
The overlaid emoji is promoted by UNICEF, courtesy of LemiWashMyHands.org
Remembering the Story
As the conversation continues beyond World Sepsis Day 2020 (Sept 13), it's worth remembering Dr Semmelweis’ courage and perseverance in resolving sepsis at his maternity ward. While his legacy has saved many lives since, safe labor remains an important United Nations Millenium Goal for the world.
175 years plus from Vienna, let’s remember the 1001 mothers and newborns from Ward 1, as we continue to bring aseptic handwashing forward to meet the challenges of our pandemic age.
Support the campaign for a hand washing emoji, here: https://lemiwashmyhands.org/
Stay safe and stay well.