sepsis

sepsis
Synonyms	Septicemia, blood poisoning
Field	Infectious disease, Critical care medicine
Complications	Septic shock, Multiple organ dysfunction syndrome
Causes	Bacterial infection, Fungal infection, Viral infection
Risks	Very young age, Old age, Immunodeficiency
Diagnosis	SOFA score, qSOFA
Treatment	Antibiotics, Intravenous fluids, Vasopressor
Frequency	Millions per year globally
Deaths	~11 million per year (2017)

sepsis. Sepsis is a life-threatening condition that arises when the body's response to an infection causes injury to its own tissues and organs. It is a major cause of mortality in hospitals worldwide, particularly within intensive care units. This dysregulated host response can rapidly progress to Septic shock and Multiple organ dysfunction syndrome, making early recognition and aggressive management critical.

Definition and overview

The most widely accepted clinical definition is based on the Sepsis-3 criteria, which describe it as a life-threatening organ dysfunction caused by a dysregulated host response to infection. This updated definition, developed by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine, emphasizes organ dysfunction, which can be identified by an increase in the SOFA score. For quicker bedside assessment outside the Intensive care unit, the qSOFA tool uses criteria like Altered mental status, low Systolic blood pressure, and high Respiratory rate. It represents a profound failure of the body's normal homeostatic mechanisms in the face of an invasive pathogen.

Causes and pathophysiology

Sepsis is triggered by a wide variety of infections. The most common sites of primary infection leading to this condition include the lungs (as in Pneumonia), the abdomen (such as from Appendicitis or Peritonitis), the urinary tract, and the skin or soft tissues. Pathogens involved are typically bacterial, including Staphylococcus aureus, Escherichia coli, and Streptococcus pneumoniae, but fungal and viral agents like Influenza can also be causative. The pathophysiology involves a complex interplay where the initial immune and coagulation responses become excessive and damaging. This leads to widespread endothelial injury, microvascular thrombosis, and ultimately, cellular dysfunction across vital organs like the kidneys, liver, and heart.

Signs and symptoms

Clinical manifestations are highly variable but often include a combination of signs indicating both infection and organ distress. Common early symptoms can resemble those of Influenza and include fever, rapid heart rate, rapid breathing, and confusion or lethargy. As organ dysfunction progresses, signs may include significantly low blood pressure (a hallmark of Septic shock), reduced urine output indicating kidney injury, jaundice from liver involvement, and shortness of breath from lung injury. The skin may appear mottled or cool due to poor perfusion.

Diagnosis

Diagnosis is primarily clinical, based on recognizing the constellation of signs in a patient with suspected or confirmed infection. The Sepsis-3 criteria recommend using the SOFA score to quantify organ dysfunction, with a rise of 2 points or more being indicative. Laboratory tests are crucial for confirmation and guidance. These typically include blood cultures, complete blood counts, measurements of lactate (elevated levels indicate tissue hypoxia), and assessments of coagulation status and renal and liver function. Imaging studies such as chest X-rays or computed tomography are used to identify the source of infection.

Treatment

Management is a medical emergency and follows time-sensitive protocols, often summarized by campaigns like the Surviving Sepsis Campaign. The cornerstone of treatment involves early administration of broad-spectrum antibiotics, ideally within one hour of recognition. Source control, such as draining an abscess or removing an infected device, is equally critical. Hemodynamic support includes aggressive intravenous fluid resuscitation, followed by vasopressor agents like norepinephrine if hypotension persists. Supportive care in an ICU often requires mechanical ventilation for respiratory failure and dialysis for renal failure.

Prognosis and epidemiology

Sepsis is a global health burden, with an estimated 49 million cases and 11 million deaths annually according to a 2017 study published in *The Lancet*. It is a leading cause of death worldwide, particularly in low- and middle-income countries. Mortality rates are highly dependent on the timeliness of intervention, the underlying health of the patient, the causative pathogen, and the number of organs that fail. Survivors often face long-term consequences, known as post-intensive care syndrome, which can include cognitive impairment, psychiatric problems, and physical disability. Major risk factors include extremes of age (neonates and the elderly), chronic illnesses like diabetes or Cancer, and immunosuppressive conditions or therapies.

Category:Medical emergencies Category:Infectious diseases Category:Critical care medicine