Sepsis is a serious condition that arises when the body’s response to an infection injures its own tissues and organs. It is a life-threatening illness that can progress rapidly, making early recognition extremely important. Approximately 1.7 million cases of sepsis occur in the United States annually, according to the Centers for Disease Control and Prevention (CDC), and it is responsible for nearly 350,000 deaths.
Key Signs and Symptoms of Sepsis
Recognizing the signs of sepsis can be challenging because its symptoms can resemble those of other illnesses like pneumonia or the flu. General symptoms often include a fever above 100.4°F (38°C) or a low body temperature below 96.8°F (36°C), accompanied by chills or shivering. A rapid heart rate (tachycardia, over 90 beats per minute) is another common indicator.
The body’s overwhelming response to infection can also manifest in signs of organ dysfunction. These include rapid breathing (over 20 breaths per minute) or difficulty breathing. Individuals might also experience confusion, disorientation, or a change in mental status, ranging from slight agitation to slurred speech or unconsciousness. Signs of infection itself, such as pain around a wound or reduced urine output, can also be present.
Medical Diagnostic Approaches and Criteria
Healthcare professionals employ specific frameworks and laboratory tests to diagnose sepsis, focusing on identifying both the presence of infection and signs of organ dysfunction. One historical framework is the Systemic Inflammatory Response Syndrome (SIRS) criteria, which involves meeting at least two of four criteria: abnormal body temperature (above 38°C or below 36°C), heart rate over 90 beats per minute, respiratory rate over 20 breaths per minute or a partial pressure of carbon dioxide less than 32 mmHg, and an abnormal white blood cell count (above 12,000 per µL or below 4,000 per µL, or more than 10% immature forms). While SIRS has been used for screening, its sensitivity for detecting sepsis is about 50% to 60%.
A more recent approach, known as Sepsis-3, defines sepsis as a life-threatening organ dysfunction caused by a dysregulated host response to infection. This definition emphasizes an increase of two points or more in the Sequential Organ Failure Assessment (SOFA) score. The quick SOFA (qSOFA) score is a simplified bedside tool used to identify patients with suspected infection. A qSOFA score of two or more points, based on a respiratory rate of 22 breaths per minute or greater, altered mental status, and systolic blood pressure of 100 mmHg or less, suggests the need for further evaluation.
Laboratory tests are also fundamental in confirming infection and assessing organ dysfunction. A complete blood count (CBC) can reveal an elevated white blood cell count (leukocytosis) or, in severe cases, a low count (leukopenia). Blood cultures are collected to identify the specific pathogen causing the infection, which guides antibiotic therapy. Lactate levels in the blood are important, as levels above 2 mmol/L can indicate tissue hypoperfusion and correlate with sepsis severity. Procalcitonin is another biomarker that increases specifically with bacterial infections and can help distinguish sepsis from other inflammatory conditions.
Additional tests may include:
- Coagulation studies
- Urinalysis
- Urine culture
- Arterial blood gases
- Specific site cultures depending on the suspected source of infection
Understanding Sepsis Severity
Sepsis can progress through different stages, with increasing severity marked by distinct clinical criteria and physiological changes. Historically, these stages were categorized as sepsis, severe sepsis, and septic shock, though the “severe sepsis” term is now less commonly used in some modern definitions like Sepsis-3.
When the organ dysfunction becomes more pronounced, it was previously referred to as severe sepsis. This stage would involve signs of organ malfunction. For example, a serum lactate level greater than 2 mmol/L can indicate tissue hypoperfusion and was a criterion for severe sepsis. The most severe stage is septic shock, characterized by profound circulatory, cellular, and metabolic abnormalities. This stage involves dangerously low blood pressure that persists despite fluid resuscitation and requires medications called vasopressors to maintain adequate blood pressure. Additionally, a lactate level greater than or equal to 2 mmol/L, indicating significant tissue hypoperfusion, is a defining characteristic of septic shock.
The Urgency of Early Identification
Prompt diagnosis of sepsis is important because every hour of delay in diagnosis and treatment increases the risk of mortality. Early detection and appropriate interventions improve the likelihood of survival for patients with sepsis. Studies have shown that a one-hour delay in initiating antibiotics can be associated with an increased risk of in-hospital mortality. For patients with septic shock, each hourly delay in antibiotic administration can increase hospital mortality by about 1.8%. Swift medical evaluation, combined with early recognition of signs and symptoms, leads to better outcomes.