Tracking Sepsis Through Blood Pressure and Pulse Pressure
Updated: Jun 6
Every year, 1.7 million people in the U.S. find themselves in a battle they never anticipated — one that starts not in the world around them, but inside their own body. It doesn't announce itself. It begins with something familiar — an infection in the lungs, a wound on the skin, a bug in the digestive tract. Ordinary. Manageable. Until it isn't.
What happens next is the body's own defense system making a catastrophic mistake — burning everything down trying to put out a small fire.
That is Sepsis.
It’s a silent predator. One minute it’s a fever, the next, your heart is racing, your breath is shallow, and your mind is clouded by confusion. Sepsis kills 13 million people yearly. That's one death every two seconds. And the survivors; suffer depression, cognitive impairment, PTSD.
What is Sepsis?
Scientifically, sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to an infection. It is not a disease caused directly by a pathogen itself; rather, it is an explosive, systemic overreaction of the body's own immune system and can quickly lead to tissue damage, organ failure, and death.
Sepsis affects your Heart!
Sepsis doesn't just threaten the body in the moment — its reach extends far beyond the infection itself, sometimes quietly damaging the heart long after a person has recovered. The extreme inflammatory response it triggers puts the heart under enormous strain, gradually weakening the muscle and disrupting its ability to function. Doctors call this sepsis-induced cardiomyopathy — a condition that can linger like an uninvited guest long after the initial storm has passed. And one of the clearest windows into what sepsis does to the heart is something as simple as blood pressure — the steady rise and fall of SBP and DBP telling the story of a circulatory system under siege.
Blood Pressure Trends in Sepsis
Blood pressure is measured with two numbers, written as systolic over diastolic (e.g., 110/70 mmHg). Both measure the force of blood pushing against your artery walls, but at different phases of your heartbeat. Systolic and Diastolic Blood pressure are very important biomarkers in the Sepsis dataset and to the heart organ.
Systolic Blood Pressure (Top Number): Measures the pressure in your arteries when your heart beats and actively pumps blood out to your body.
Normal Range: 90–120 mmHg
Diastolic Blood Pressure (Bottom Number): Measures the pressure in your arteries when your heart muscle relaxes and rests between beats.
Normal Range: 60–80 mmHg
SBP and DBP were continuously monitored for each patient throughout their ICU stay. Tracking these values over 340-hour monitoring period helps assess cardiovascular function, detect low blood pressure episodes, and monitor the progression and severity of sepsis.
At first glance this chart looks like a storm — and that is exactly what it represents. In the early hours, SBP and DBP are anything but steady, lurching between dangerous lows and hypertensive spikes above 160. Behind those numbers are constant clinical interventions — fluids, vasopressors, adjustments — a medical team doing everything possible to keep a patient's circulatory system from collapsing entirely.
Gradually, the storm passes. As the hours climb toward 340, the volatility softens and the moving averages begin to converge. It is a quiet but significant moment in any patient's journey — the point where the data stops telling a story of crisis and starts telling one of recovery.
While SBP and DBP individually provide valuable information about cardiovascular status, combining them allows us to calculate Pulse Pressure (PP), an important measure that can reveal how sepsis affects blood flow and blood vessel function over time.
Pulse Pressure
Pulse pressure is the difference between your systolic (top) and diastolic (bottom) blood pressure numbers. It measures the force your heart exerts each time it beats and is a key indicator of arterial stiffness and overall heart health.
Normal Range: 30 to 50 mmHg.
Example: If your reading is 110/70 mmHg, the pulse pressure is 40 mmHg.
Pulse Pressure (PP) helps clinicians understand how well blood is circulating during sepsis and can provide clues about shock severity and patient outcomes. A normal pulse pressure is typically 30–50 mmHg. In early sepsis, marked vasodilation (>70 mmHg) or a wide pulse pressure (50–70 mmHg) may occur as blood vessels relax and diastolic pressure falls. As the condition worsens, narrow pulse pressure (<30 mmHg) can develop, indicating that the heart is pumping less blood and organs may not be receiving enough oxygen. An extremely narrow pulse pressure (<20 mmHg) is often associated with severe septic shock, signaling critical circulatory failure and a high risk of organ damage. Monitoring pulse pressure can therefore help track the progression from early sepsis to advanced septic shock.
To better illustrate how pulse pressure changes as sepsis progresses, the following chart categorizes patients based on their pulse pressure ranges over time. Using MAX() is clinically justified because sepsis is defined by sudden, acute deterioration; it flags patients by their peak physiological stress and highest risk window rather than letting stable hours wash out their critical crashing moments.
Pulse Pressure = [SBP]-[DBP]
Pulse Pressure Range = IF { FIXED [Patient ID] : MAX([Pulse Pressure]) } < 20 THEN
"Severe Shock"
ELSEIF { FIXED [Patient ID] : MAX([Pulse Pressure]) } < 30 THEN
"Narrow (Low CO)"
ELSEIF { FIXED [Patient ID] : MAX([Pulse Pressure]) } <= 50 THEN
"Normal"
ELSEIF { FIXED [Patient ID] : MAX([Pulse Pressure]) } <= 70 THEN
"Wide (Septic Pattern)"
ELSE
"Marked Vasodilation"
END
Note: All thresholds presented in this analysis are intended for educational and analytical purposes only and should not be used for clinical diagnosis or medical decision-making.
This chart tracks the worst clinical moments for your patients to show how severely sepsis strains the heart.
The Early Spike: The vast majority of sepsis patients are concentrated in the Marked Vasodilation (2,184 patients) and Wide (573 patients) groups. Early on, the infection forces blood vessels to completely relax, causing the bottom blood pressure number to plummet and creating a massive gap that shows the heart is working in overdrive.
The Danger Zone: A much smaller, critical group dropped into the Narrow (11 patients) and Severe Shock (1 patient) groups. This captures the exact moments the heart muscle became too exhausted to pump effectively, dangerously narrowing the blood pressure gap as the body began to fail.
The story of sepsis is ultimately a story of the body's fight to survive. Through blood pressure and pulse pressure trends, we can watch that fight unfold—from early cardiovascular stress to severe shock. Behind every data point is a patient whose outcome depends on recognizing these warning signs early and acting before the body reaches its breaking point.
Thank you for reading.
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