Sepsis and septic shock are serious medical conditions that are a leading cause of death in hospitals. Both involve the body’s response to an infection, but they represent different stages along the spectrum of sepsis progression. Understanding the difference between sepsis and septic shock is important for early recognition and rapid treatment of these life-threatening conditions.
Sepsis refers to the body’s extreme response to an infection which can lead to tissue damage, organ failure, and death. When sepsis worsens, it can progress to septic shock, which involves extremely low blood pressure that cuts off blood supply to vital organs. Septic shock has a higher risk of mortality compared to sepsis. However, with quick medical care, outcomes can be improved for both sepsis and septic shock.
What is Sepsis?
Sepsis is a life-threatening condition triggered by the body’s immune response to an infection. Bacterial infections are the most common cause, but sepsis can also be caused by viral, fungal or parasitic infections.
Common sites for infections leading to sepsis include:
– Lungs (pneumonia)
– Kidney (pyelonephritis)
– Abdomen (appendicitis)
– Bloodstream (bacteremia)
– Urinary tract (UTI)
– Skin/soft tissue (cellulitis)
Sepsis develops when chemicals released into the bloodstream to fight an infection trigger inflammation throughout the body. This inflammation can damage multiple organ systems, even tissues and organs far from the infection site.
Sepsis is sometimes referred to as blood poisoning or septicemia. However, septicemia describes the presence of microorganisms or their toxins in blood and does not necessarily indicate sepsis is present. Sepsis is recognized based on systemic signs and symptoms of infection.
Signs and Symptoms of Sepsis
Common signs and symptoms of sepsis include:
– Fever above 101°F (38°C) or below 96.8°F (36°C)
– Heart rate higher than 90 beats per minute
– Respiratory rate higher than 20 breaths per minute
– Probable or confirmed infection
– Signs of organ dysfunction like kidney failure or confusion
Other symptoms may include:
– Chills or shivering
– Extreme pain or discomfort
– Clammy or sweaty skin
– Lethargy or disorientation
– Shortness of breath
Severe Sepsis
Severe sepsis refers to organ dysfunction resulting from sepsis. Signs of organ dysfunction and severe sepsis include:
– Low blood pressure
– Decreased urine output
– DIC (disseminated intravascular coagulation)
– Impaired liver function
– Changes in mental status
– Difficulty breathing
– Abnormal heart pumping function
Severe sepsis dramatically increases the risk of mortality compared to sepsis alone. Patients with sepsis can rapidly progress to severe sepsis as the infection worsens and inflammation affects organ systems. Seeking urgent medical attention at the first signs of sepsis is vital to prevent complications of severe sepsis.
What is Septic Shock?
Septic shock represents the most severe stage in the sepsis spectrum and has the highest risk of death. Septic shock happens when sepsis leads to life-threatening low blood pressure that cuts blood supply to body tissues.
In septic shock, the infection and inflammatory response cause a drop in blood pressure that remains extremely low despite intravenous fluid treatment. Septic shock leads to multiple organ failure due to inadequate blood and oxygen circulation.
Signs and Symptoms
Signs and symptoms of septic shock include:
– Systolic blood pressure less than 90 mmHg
– Mean arterial pressure (MAP) less than 65 mmHg
– Decreased blood flow to organs
– Lactate level greater than 2 mmol/L
– Extremely low urine output or no urine output
Other symptoms are similar to severe sepsis, including:
– Confusion or lethargy
– Rapid heart rate
– Rapid breathing
– Cold, clammy skin
– Mottled or blue skin in extremities
Septic Shock Pathophysiology
In septic shock, massive inflammation causes peripheral blood vessels to dilate, increasing blood flow while decreasing vascular resistance. This reduces blood return to the heart and lowers blood pressure.
As blood pressure drops drastically, the heart beats faster to try increasing circulation, but this tachycardia eventually leads to poor heart function. The body redirects circulation away from peripheral tissues to prioritize vital organs. However, diminished overall blood flow can still damage the lungs, kidneys, and other organs.
Poor circulation stimulates increased adrenaline and angiotensin II to increase blood pressure through vasoconstriction. But in septic shock, blood vessels cannot constrict effectively due to the extreme inflammation. The body’s autoregulation fails, leaving tissues hypoxic from inadequate blood flow and oxygen delivery.
Differences Between Sepsis and Septic Shock
Progression
The key difference between sepsis and septic shock is that sepsis can lead to septic shock. Sepsis represents the initial systemic inflammatory response while septic shock refers to the decreased blood flow and oxygen delivery that can result from worsening sepsis. Not all cases of sepsis progress to septic shock.
Severity
Septic shock represents more severe sepsis. Septic shock has a higher mortality rate compared to sepsis or severe sepsis. The risk of death for sepsis is around 10-20%, but increases to 40-60% in septic shock.
Blood Pressure
Sepsis may present with normal to high blood pressure as the heart works harder to pump blood during the inflammatory response. Septic shock is defined by extremely low blood pressure that does not adequately perfuse tissues with oxygenated blood.
Treatment Response
Sepsis often responds to IV fluid resuscitation alone, but septic shock requires vasopressors like norepinephrine along with fluids to increase the dangerously low blood pressure. Refractory septic shock does not improve with standard treatment.
Organ Dysfunction
While sepsis can involve some degree of organ dysfunction, septic shock progresses to more severe failure of multiple organs like the heart, lungs, and kidneys due to global tissue hypoxia. The degree of organ failure is higher in septic shock.
| Characteristics | Sepsis | Septic Shock |
|---|---|---|
| Definition | Life-threatening organ dysfunction due to dysregulated host response to infection | Sepsis with persistent hypotension and tissue hypoperfusion despite adequate fluid resuscitation |
| Blood pressure | Normal to high | Systolic BP < 90 mmHg, MAP < 65 mmHg |
| Vasopressor requirement | Not required | Required to maintain MAP ≥65 mmHg |
| Lactate level | Normal to elevated | > 2 mmol/L |
| Urine output | Normal to decreased | Minimal or no urine output |
| Mortality rate | 10-20% | 40-60% |
Early Recognition of Sepsis and Septic Shock
Early identification of sepsis is critical, as 30% of patients can rapidly progress to septic shock. Doctors use scoring systems like SOFA and qSOFA to screen patients and stratify sepsis severity.
SOFA Score
SOFA stands for Sequential Organ Failure Assessment. It evaluates function in 6 organ systems:
– Respiratory (PaO2/FiO2 ratio)
– Coagulation (platelets)
– Liver (bilirubin)
– Cardiovascular (blood pressure)
– Central nervous system (Glasgow Coma Scale score)
– Renal (creatinine or urine output)
Each organ system is scored from 0 to 4 points based on degree of dysfunction. A total SOFA score ≥2 reflects probable sepsis.
qSOFA Criteria
qSOFA stands for quick SOFA and provides simple bedside criteria to quickly assess sepsis probability:
– Respiratory rate ≥22/min
– Altered mental status (GCS score <15)
- Systolic blood pressure ≤100 mmHg
A positive qSOFA score (≥2 criteria met) indicates high risk of poor outcomes typical of sepsis. However, SIRS criteria can also be used to screen for sepsis.
SIRS Criteria
– Fever >38°C (100.4°F) or hypothermia <36°C (96.8°F)
- Heart rate >90 beats/min
– Respiratory rate >20 breaths/min or PaCO2 <32 mmHg
- White blood cell count >12,000/mm3, <4,000/mm3, or >10% immature bands
Meeting ≥2 SIRS criteria in the presence of suspected infection indicates sepsis. Routine screening for sepsis using qSOFA, SOFA or other criteria allows for prompt identification and treatment.
Treatment of Sepsis and Septic Shock
Sepsis and septic shock are medical emergencies requiring rapid diagnosis, close monitoring and treatment in the ICU. Treatment focuses on:
Infection Source Control
– Administer broad-spectrum antibiotics within 1 hour of sepsis recognition.
– Drain abscesses or infected fluid collections.
– Debride infected wounds.
– Remove infected devices.
Hemodynamic Support
– Give 30 ml/kg intravenous crystalloid fluid for hypotension or lactate ≥4 mmol/L.
– Start vasopressors for low blood pressure not responding to initial fluid resuscitation.
– Give dobutamine or epinephrine for myocardial dysfunction.
– Avoid excessive fluid administration after initial management.
– Transfuse blood for anemia.
Adjunctive Therapies
– Administer lung-protective ventilation for acute respiratory distress syndrome (ARDS).
– Maintain adequate glucose control.
– Prevent complications like stress ulcers and blood clots.
– Consider immunoglobulins, corticosteroids or blood purification techniques in refractory septic shock.
Prevention
While sepsis and septic shock can happen unpredictably, certain prevention measures in hospital settings can help lower risk:
– Vaccinate at-risk patients against flu, pneumonia and other infections.
– Follow sterile protocols for urinary and central IV catheters.
– Implement contact precautions for antibiotic-resistant bacteria.
– Educate patients and healthcare workers on infection control.
– Follow bundled best practice protocols for sepsis management.
Community-acquired sepsis often originates from a preventable infection like pneumonia, highlighting the importance of public health initiatives to increase vaccine coverage and access to care. People with chronic diseases or weakened immune systems should be especially vigilant for infections that may spiral into sepsis or septic shock.
Prognosis and Outcomes
Sepsis and septic shock have high mortality rates, especially in vulnerable populations like the elderly. However, outcomes have improved with increased awareness and research on treatments.
Mortality rates for sepsis:
– Overall mortality 10-20%
– Under age 30: 2-4%
– Age 85 and older: up to 50%
Mortality rates for septic shock:
– Overall mortality 30-50%
– With appropriate antibiotics and source control, 20-30%
– Untreated septic shock up to 80%
Survivors of sepsis and septic shock may suffer long-term complications like chronic organ dysfunction, neurocognitive decline, and post-traumatic stress disorder (PTSD). Ongoing monitoring and rehabilitation is important in the months following hospital discharge.
Conclusion
Sepsis refers to life-threatening organ dysfunction due to uncontrolled infection, while septic shock is sepsis with dangerously low blood pressure and oxygen delivery to tissues. Though related, the key difference between sepsis and septic shock lies in the severity of circulatory failure and degree of tissue hypoxia.
Rapid diagnosis and treatment of both sepsis and septic shock is vital to improve chances of survival. Increased public awareness on recognizing the early signs of sepsis allows patients to seek prompt medical care, giving clinicians the opportunity to halt progression to more severe septic shock. Ongoing research continues to advance understanding and management of these deadly conditions.