Analytics February 26, 2020

From Snow to Achuff: Using Analytics to Drive Clinical Change

by Barry P Chaiken, MD


John Snow, the English physician who removed the handle from the Broad Street pump and halted the 1854 London cholera epidemic, is considered one of the founders of modern epidemiology. His work led to fundamental changes in the water and waste system of London and other cities around the world. He was one of the first physicians to calculate doses for various forms of anesthetic, allowing patients to undergo procedures with limited pain.

In the mid-19th century, Londoners obtained their drinking water from pumps located throughout the city that drew water from public wells or the Thames river. Unlike today, the Thames was quite polluted acting as both a source of fresh water and a means for waste disposal. In addition, many homes sat above private cesspools as a comprehensive sewer system did not exist. It was not uncommon for a drinking well to be located relatively close to some of these homes.

While the germ theory of disease had not yet been developed, Snow nevertheless rejected the then popular miasma theory which postulated that diseases such as cholera and bubonic plague originated from noxious forms of “bad air.”

Drawing on his knowledge of statistics, Snow decided to plot the homes of each cholera victim on a street map. His dot map revealed a cluster of cholera deaths around a single water pump located on Broad Street (now Broadwick Street). Snow’s work led to the removal of the handle of the Broad Street pump and the end of the cholera outbreak. Subsequent work linked cholera cases to contaminated water taken from the Thames and distributed to various parts of London by a private water company.

Despite Snow’s work, government officials considered the fecal oral route of disease transmission too startling for the public to accept and therefore rejected his theories. Snow’s experience is an example of the challenge health officials even today face in their effort to protect the public (e.g., measles).

Father of clinical visualization

The importance of analytics in epidemiology makes a strong case that Snow can also be viewed as one of the founders of clinical visualization analytics. In his work, Snow used statistical techniques and visualizations to make his argument (e.g., cholera dot map).

At a recent analytics conference, a visionary clinician from Texas Children’s Hospital, Barbara-Jo Achuff, MD, illustrated the importance of epidemiology and analytics in clinical care, drawing a direct link to the work of Snow in London more than a 150 years ago.

As an attending in the Cardiac Intensive Care Unit (CICU) Achuff cares for very sick infants and children with heart disease. While requiring effective sedation to allow for proper healing, sedation poses a risk to young children. In 2016, the U.S. Food and Drug Administration (FDA) issued the following warning:

“…repeated or lengthy use of general anesthetic and sedation drugs during surgeries or procedures in children younger than 3 years or in pregnant women during their third trimester may affect the development of children’s brains.”(2)

This new risk factor made tracking of sedation dosing a critical part of the care of young children in her CICU. Recognizing that sedation medication data was available within the hospital’s electronic medical record (EMR) system, she worked with her information technology staff to generate daily CICU medication administration extracts. Achuff then applied visualization analytics software to the extracts to track point and total sedation levels for every patient treated in her unit.

She also included the sedation tracking visualizations in her daily patient rounding workflow for herself and her clinical colleagues. Using the knowledge gained from tracking sedation using the dashboards, Achuff and her team developed sedation treatment protocols to standardize treatment across the CICU to minimize sedation and the impact of the medications on brain development in these vulnerable children. Her work delivered these results:

    • Steady decrease in sedation dosing and use of bolus doses
    • Decreased lengths of stay
    • Increased effectiveness of targeted in-service sedation education
    • Improved quality and use of clinical sedation protocols

Including the daily surveillance sedation dashboards in clinical workflow helps ensure that the critical issue of sedation dosing is properly monitored. In addition, patient-specific tracking allows for the identification of children who are non-responders to the administered sedation medications. Such non-responders require higher doses of first line sedation drugs, something easily identified on sedation dashboards.

These children can then be switched to more effective second choice medications that require lower dosing and present less of a threat to brain development during these critical first few years of life. Most non-responder children are discovered within two days of the start of sedation when using sedation dashboards, a discovery period much shorter than previously recorded.

150 year link

The link between Snow and Achuff spans more than 150 years of conceptualization, experimentation, and discovery. During that time, our understanding of disease grew exponentially, the technology tools at our disposal to diagnose and treat disease expanded (e.g., magnetic resonance imaging, robotics, sensors), and our ability to collect and analyze enormous quantities of data exploded (e.g., EMR, Haadoop, visualization software).

It took 12 years from Snow’s initial work for the government to officially link the cholera outbreak to a source of drinking water. We can only imagine how impactful Snow’s work could have been if he had access to the dashboard and visualization tools available today.

Properly designed and focused dashboards immediately impact clinical care. Patient sedation at Texas Children’s Hospital’s CICU follows a very different path than it did a few years ago. Both patients and clinicians are actively monitored to ensure proper adherence to best practices.

Available analytics and visualization software offer clinicians effective and easy to deploy tools to directly impact patient care. As clinical subject matter experts, they are tasked to develop use cases for clinical dashboards and to work with technical experts to deploy them. To be effective requires a partnership and trust between these two groups. By joining together, these experts can mine new knowledge and deploy it to improve patient health and save lives. The visualization analytics journey started by Snow and joined by Achuff continues, offering enormous benefits to clinicians and their patients.


  3. Achuff BJ, Welt A. “Visualizing Success in the Cardiac ICU Texas Children’s Hospital”. November 13, 2019, Tableau Conference 2019, Mandalay Bay Conference Center, Las Vegas NV, Conference Presentation.

Excerpts from from “Snow to Achuff: Using Analytics to Drive Clinical Change” published in Patient Safety and Quality Healthcare

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