Sepsis or septicemia is a clinical syndrome characterized by an abnormal Systemic Inflammatory Response (SIRS), implemented by the body following the passage of pathogenic microorganisms from a sepsigen outbreak into the blood. If the phlogistic component is missing, we no longer speak of sepsis, but of "simple" bacteremia (presence of bacteria in the blood demonstrated by at least one positive blood culture).
Sepsis is a potentially very serious condition that passes through stages of gravity
Signs and symptoms
To learn more: Sepsis symptoms
The clinical symptomatology of sepsis is supported by the interaction between the toxic products of the causative agent (bacteria, viruses, fungi) and the response of the host. These symptoms are rather non-specific and include fever, tachycardia, skin discoloration and increased respiratory rate. It is no coincidence that the diagnosis of sepsis is made following the finding of at least two of the following criteria that identify the SIRS, provided they are accompanied by an infectious, intravascular (endocarditis, endarteritis, arterio-venous shunt infections) or extravascular (abscesses, wounds) etc.), which is the determining factor:
- body temperature> 38 ° C (hyperthermia) or <36 ° C (hypothermia);
- heart rate> 90 beats / min or 2 standard deviations higher than the normal value for age (tachycardia);
- hyperventilation with respiratory rate> 20 acts / min (tachypnea) o
- hyperventilation demonstrated by a PaCO 2 <32 mmHg;
- alteration of the leocucitary formula, with white blood cell count> 12000 μL-1 cells (leukocytosis) or <4000 μL-1 (leukopenia).
We speak instead of severe sepsis when at the previous diagnosis is added at least one of the following signs related to organ failure:
- significant decrease in urine production (oliguria, diuresidiuresi <0.5 ml / Kg / h);
- abrupt change in mental state;
- breathing difficulties (hypoxemia);
- abnormal cardiac activity;
- reduction in the number of platelets in the blood (thrombocytopenia / thrombocytopenia);
- appearance of small red-dark patches on the skin or general redness.
In the last and more serious stage, septic shock, the characteristic signs and symptoms of severe sepsis are added to an extremely low blood pressure (severe hypotension), which is maintained even in the presence of an adequate volume state and despite the restoration of volume through fluid therapy.
Sepsis is a syndrome that develops after an infection, localized or systemic, which causes many inflammatory chemical mediators to be released into the circulation. In the presence of sepsis, therefore, an increased plasma concentration of C-reactive protein, interleukin-6 and procalcitonin is appreciated; it can also be noted, as anticipated in the pathognomic symptoms, leukocytosis (increased number of white blood cells) or leukopenia (reduced number of white blood cells).
Causes and Risk Factors
Sepsis is triggered by the concurrence of two factors: on the one hand the infection of a normally sterile tissue by pathogens (bacteria, fungi, viruses) and on the other the exaggerated systemic inflammatory response (SIRS) of the organism. Among the microorganisms most frequently involved in septic episodes are Escherichia coli, Klebsiella spp. , Pseudomonas spp., Candida spp., Methicillin-resistant staphylococci.
Inflammation is one of the weapons our body uses to fight infections. While in normal conditions there is a balance between pro and anti inflammatory factors, in sepsis the inflammatory response becomes exaggerated and systemic (it spreads from the site of infection to the whole organism). Consequently, microscopic clots (thrombi) form inside the blood vessels, due to the increase in the biochemical phenomena that generate them and the reduction of those that "dissolve" them. The heart is thus forced to pump blood in circulation with greater force, while the organs suffer from the reduced supply of oxygen and nutrients.
Regarding the risk factors of sepsis, this condition can potentially affect any subject. There is no doubt, however, that the very young age (childhood) and old age (> 65 years) expose the individual to a greater risk of suffering a septic phenomenon. Other predisposing factors are alcohol and drug abuse, impaired immune system and organic debility (renal or hepatic failure, AIDS, cancer or anticancer therapies, anti-rejection therapy after organ transplantation, prolonged cortisone therapy), from the black race to the Caucasian one and from particular medical conditions (bacterial invasion of blood or septicemia, dental abscesses, pneumonia, urinary infections, perforated appendicitis, meningitis, diabetes and severe traumas such as extensive burns or gunshot wounds). We must not forget that sepsis is a fairly frequent occurrence in people admitted to intensive care, who are the ones most exposed to septic risk and its most feared consequences. Also the intubation, the application of urinary catheters or other invasive devices significantly elevates the risk of suffering septic phenomena.
Sepsis is one of the most common causes of morbidity and mortality, especially in elderly, immunocompromised and severely ill patients.
Complications and treatment
See also: Medicines for the treatment of sepsis
As we have seen, sepsis can pass through three stages of increasing gravity; the higher this level is, the greater is the impairment of blood supply to vital organs, such as the brain and kidneys; necrotic phenomena (gangrene) are therefore more frequent, especially of the body extremities, and organ insufficiencies. Most individuals subject to moderate septic episodes recover from the event; not by chance the average mortality rate is 15%, while it rises to 30-35% in severe septic episodes, up to over 50% in septic shock.
In Italy, sepsis has an average incidence of 1.5 cases per thousand inhabitants.
Early and aggressive treatment considerably increases the chances of survival. In this regard - without prejudice to the need for hospitalization in intensive care in the most severe cases - antibiotics, fluids and blood products can be administered (infusion of liquids in the blood for hemodynamic support, in order to increase the volume and blood pressure), vasopressor drugs (which due to vasoconstriction raise blood pressure), insulin, sedatives or painkillers, and immune system modulators. In patients with severe sepsis oxygen therapy (intubation, artificial lung) or dialysis may be necessary (to compensate for reduced renal function in blood purification).