Sepsis is a medical emergency that occurs when the body’s response to an infection injures its own tissues and organs. It is not the infection itself, but the resulting widespread inflammation that causes damage throughout the body. This condition is responsible for nearly 350,000 deaths annually in the United States, making rapid identification and treatment crucial. Medical professionals describe sepsis as progressing through three distinct stages of increasing severity, which guides the speed and intensity of treatment.
Stage 1: The Body’s Initial Systemic Response
This stage begins when an infection, such as pneumonia or a urinary tract infection, triggers a systemic inflammatory reaction. The immune system releases chemicals into the bloodstream to fight the invading germs. While intended to be protective, this widespread chemical release causes a chain reaction that affects the entire body.
The initial response is characterized by common physical signs. These include an abnormally high or unusually low body temperature. The heart rate typically speeds up to over 90 beats per minute, and breathing becomes rapid, often exceeding 20 breaths per minute.
The patient may also exhibit mental status changes, such as confusion or disorientation, along with chills and clammy skin. During this stage, the problem remains primarily systemic inflammation, and the function of major organs has not yet measurably deteriorated. Early diagnosis and aggressive treatment with antibiotics offer the best chance for a full recovery.
Stage 2: Onset of Organ Dysfunction
If the systemic inflammation is not quickly contained, the condition progresses to organ dysfunction. The rampant inflammatory response begins to damage the lining of blood vessels and causes tiny blood clots to form throughout the circulatory system. This process severely impairs blood flow, starving vital organs of the oxygen and nutrients needed to function.
The signs of this stage are specific to the affected organ systems. Kidney dysfunction often manifests as a noticeable decrease in or complete absence of urine output. Lung involvement can lead to difficulty breathing, sometimes requiring mechanical assistance. The brain is highly susceptible to low blood flow, resulting in severe mental changes like delirium or extreme lethargy.
Failure of one or more organs marks a worsening of the patient’s condition. Documented organ dysfunction means the body is actively being harmed by its own response to the infection. Immediate medical intervention is necessary to reverse the damage before it becomes permanent.
Stage 3: Refractory Circulatory Failure
The final stage is known as septic shock, which occurs when circulatory failure becomes profound and unresponsive to initial treatment efforts. The defining feature is dangerously low blood pressure, or hypotension, that persists even after the patient has received substantial intravenous fluids. This sustained drop in pressure results from massive dilation and leakage from the blood vessels throughout the body.
The blood vessels widen significantly and leak fluid into surrounding tissues, which reduces the effective circulating blood volume and causes pressure to plummet. The heart attempts to compensate by beating faster, but it cannot overcome the profound circulatory instability. This persistent low blood pressure prevents oxygenated blood from reaching tissues, leading to cellular starvation and metabolic abnormalities.
Patients in septic shock often require immediate advanced life support, including powerful medications called vasopressors. These medications constrict the blood vessels and raise the blood pressure to a survivable level. This severe stage is associated with the highest rates of mortality, emphasizing the importance of recognizing the earlier signs of sepsis to prevent progression.