Blood poisoning (sepsis): causes, course, treatment
Blood poisoning: Description
Blood poisoning is not, as is often assumed, caused by the presence of pathogens in the blood, but by the body’s reaction to them. The causes of blood poisoning are usually bacteria. In rare cases, blood poisoning is caused by viruses, protozoa or fungal pathogens (candida). The immune system tries to defend itself against the pathogens, but this fight not only harms the intruders, but also the body itself. Sepsis is a potentially life-threatening disease and should be treated consistently as soon as possible. A distinction is made in the definition of sepsis depending on the severity of the blood poisoning.
Forms of sepsis
If you find bacteria in your blood (bacteremia), this does not mean that you have blood poisoning. Such a find has no disease value in itself. Small amounts of bacteria penetrate the blood stream through micro-injuries in the gums, for example, when brushing teeth, without triggering a body-wide inflammatory reaction. The body’s healthy immune system can easily deal with such small amounts of pathogens. Only when this is no longer the case and one becomes ill as a result of this struggle is one called blood poisoning (sepsis). The main indications of blood poisoning are the following symptoms in adults:
- a deviation of the body temperature upwards or downwards (<36°C or >38°C)
- an increased pulse (>90 beats/minute)
- an increased breathing frequency (>20 breaths/min)
- a deviation in the number of white blood cells in the blood (leukocytes) (<4000/µL or >12.000/µL)
If these points are fulfilled, one speaks of SIRS (Systemic Inflammatory Response Syndrome), but not yet of sepsis.
SIRS (Systemic Inflammatory Response Syndrome)
You can read more about the triggers and events in a systemic inflammatory reaction of the body in the article SIRS.
The criteria for blood poisoning (sepsis) are met as soon as an infectious cause for the body reaction can be identified. If organs are impaired in their function, the definition of sepsis is severe sepsis. Causes for organ failure can be blood clots, severely lowered blood pressure or reactions to the body’s own messenger substances, which actually serve to fight the pathogens. The risk of dying from the consequences of severe sepsis is about 47 percent.
If the blood pressure can no longer be kept at a sufficient level due to this endogenous inflammatory reaction, this is called “septic shock“. This final stage of blood poisoning consequently endangers the blood supply to vital organs and leads to death in more than half of those affected.
In the article Septic Shock you can read more about the risks in the final stages of septicemia.
A special case of blood poisoning is the so-called newborn sepsis. It describes blood poisoning in babies in the first month of life. There are typically two types, depending on how quickly sepsis occurs after birth. The so-called early onset sepsis, in which the pathogen was most likely transmitted by the mother during the birth process, occurs within the first four days of life. This is known as late onset sepsis. However, new studies show that this subdivision has no significant relevance for treatment.
The sepsis criteria of newborn sepsis are more difficult to detect than in adult patients. The newborn sepsis is feared because of its brilliant course. In babies, blood poisoning can become a life-threatening condition much more quickly. As a rule, the mother is examined for bacteria in her vagina before birth, which could potentially endanger the child. As a result of this investigation, and strict hygiene regulations, the incidence of newborn sepsis cases has been drastically reduced in industrialized countries in the last decade.
Blood poisoning: symptoms
You can read everything important about the typical signs of sepsis in the article Blood poisoning – symptoms.
Blood poisoning: causes and risk factors
In principle, any infection can lead to sepsis (blood poisoning), but it does not have to. Blood poisoning cannot be specifically prevented. In principle, however, it is advisable to have any infection – even if it seems harmless at first – treated by a doctor at an early stage.
Sepsis (blood poisoning) begins with a localised infection, the causes of which are mostly bacteria, sometimes also viruses, fungi (candida sepsis) or so-called protozoa (unicellular organisms). The immune system starts defensive reactions against the intruders in the form of inflammation: The blood circulation in the affected tissue is increased and the permeability of the blood vessels is increased. This allows large quantities of white blood cells (leukocytes) to reach the site of infection and enter the tissue, where they eliminate the pathogens and destroyed cells.
However, the concentrated defences of the immune system are sometimes not sufficient to limit and eventually eliminate the infection at its source. The pathogens then gain the upper hand: the pathogens and their toxins enter the bloodstream. According to the definition of sepsis, in this case one does not yet speak of blood poisoning, but first of bacteremia (bacteria in the blood).
If these substances now trigger a body-wide inflammatory reaction, this is known as the typical course of sepsis. The corresponding symptoms of sepsis are related to this body-wide battle between the immune system and pathogens. Vessels throughout the body dilate, causing a drop in blood pressure, signs of inflammation in the blood increase dramatically, the heart and lungs try to compensate for the lack of backflow of blood and its accumulation of oxygen by working harder, thereby increasing breathing and heart rate.
Due to the altered blood flow and damage to vessels and tissue by the pathogens and the immune system, the blood coagulates faster. On the basis of the sepsis criteria, one speaks of a severe sepsis as soon as organs are damaged in their function by small blocked vessels (thrombi) or other harmful substances.
If the pumping power of the heart is no longer sufficient to transport enough blood to the vital organs, this is also known as septic shock.
Risk groups: Sepsis
Causes of blood poisoning can in principle be all localised infections (such as pneumonia or urinary tract infections). Hospital infections (nosocomial) are often the cause of sepsis. The risk of blood poisoning is particularly high in the case of
- very young (newborns) and very old people
- a weakened immune system (e.g. due to chemotherapy for cancer or high-dose cortisone therapy for rheumatism or respiratory diseases)
- Wounds or injuries (e.g. extensive burns)
- Certain treatments and examinations (e.g. catheters in blood vessels, bladder catheters, wound drainage)
- Addictions (e.g. alcoholism, drug addiction)
- Genetic predisposition for sepsis
Blood poisoning: examinations and diagnosis
If blood poisoning is suspected, the following sepsis criteria are checked:
- Presence of an infection, e.g. by microbiological detection of pathogens in a patient sample (blood sample, urine sample, wound swab) or pneumonia on the basis of an X-ray
- Fever (at least 38 degrees Celsius) or low temperature (36 degrees Celsius or less), measured with a thermometer in the anus (rectal), in a blood vessel (intravascular) or in the bladder (intravesical)
- Heart rate of at least 90 beats per minute (tachycardia)
- certain changes in the large blood count: leukocyte count (white blood cells) either increased (≥ 12,000/ µL) or decreased (≤ 4,000/ µL) or ≥ ten percent immature neutrophils (subgroup of white blood cells)
- Increase in the inflammation parameters CRP (C-reactive protein) or pro-calcitonin
- defective organ function, for example in the brain (limited attention, disorientation, restlessness, confusion, delirium, coma, loss of sensation in one part of the body, movement restrictions), the liver (increased liver enzymes and bilirubin, skin color changes), kidney (decreased urine excretion, decreased blood pH, increased creatinine), lungs (decreased oxygen and increased carbon dioxide levels in the blood)
- Coagulation disorders, decrease in the number of blood platelets (thrombocytes)
As soon as the restriction of an organ function is detected, one speaks of a severe sepsis. This also applies if the causes of sepsis have not yet been clarified. If a critical drop in blood pressure is added to this, it is called septic shock.
Blood poisoning: treatment
A prerequisite for a successful therapy of sepsis is the treatment of the underlying disease – i.e. the infection that led to blood poisoning. It can be done surgically or by medication. The treatment of blood poisoning therefore always begins with the search for the source of infection. For example, an inflamed appendix or an infected joint prosthesis can be the trigger. Even seemingly banal things like a vascular access on the arm, or a urine catheter can cause blood poisoning.
Most often the focus is in the lungs, abdomen, urinary tract, skin, bones and joints, teeth or central nervous system (e.g. meningitis, encephalitis). Foreign material in the body can also be the seat of the source of infection, for example screws and plates used in bone surgery or the “coil” (IUD) for contraception.
If possible, this starting point of the sepsis is eliminated as quickly as possible – in technical jargon this procedure is called “remediation”. However, in about 20 percent of sepsis patients, the source of the infection cannot be identified.
Treatment of simple sepsis
In the case of simple sepsis, a stay in the intensive care unit is usually not necessary. Here it is enough to eliminate the source of infection and start a therapy with antibiotics, since bacteria are usually responsible for blood poisoning. If it is a fungal (Candida sepsis), viral or parasitic infection, it must be treated accordingly.
Treatment of severe sepsis
In the case of severe blood poisoning, in addition to removing the source of infection and antibiotic therapy, the limited organ functions must also be taken into account. With this more dangerous course of sepsis, the equipment of an intensive care unit is actually always necessary.
In any case, the pathogen should be named and analysed precisely in order to be able to select the best therapy. Depending on the pathogen, one can then select a specific antibiotic or an antifungal agent (antimycotic), for example.
Additional measures of sepsis treatment in the intensive care unit:
- the replacement of fluid by infusion and possibly nutrient solutions when patients can no longer eat The latter can also be done by probe through the nose into the stomach (stomach tube)
- the replacement of blood cells and plasma by transfusion if necessary
- supporting the function of affected organs, for example by artificial respiration in the event of (imminent) lung failure or dialysis, which relieves the kidneys of the task of filtering blood.
- the administration of painkillers and sedatives
- if necessary, insulin therapy to lower blood sugar levels, since some patients with sepsis have an increased blood sugar level
- Prevention of a so-called stress ulcer – an ulcer in the stomach or duodenum caused by body stress that can cause bleeding. Proton pump inhibitors or histamine 2 receptor blockers are mainly used.
- the administration of anticoagulants to prevent blood clots (thromboses), which can form anywhere in the body in the event of severe sepsis
Newer therapies with artificial antibodies (immunoglobulins) may be considered in severe cases. However, there is still a lack of knowledge about which antibodies are most effective in which form of sepsis. For this reason, this treatment for blood poisoning is not yet recommended as a standard.
Treatment of septic shock
In addition to the above-mentioned procedures, septic shock has the additional problem that sufficient blood pressure and the pumping function of the heart must be ensured in order to continue to supply all organs with sufficient blood.
So-called vasopressor (vasoconstrictive) substances increase blood pressure when it has dropped due to septic shock. (see sepsis criteria in the “Symptoms” section).
In addition, one tries to keep the vessels in a filled state by a high fluid intake by infusion, because due to their dilatation, a lot of blood in the periphery (arms, legs, tissue) as well as in the tissue is blocked and does not flow back to the heart fast enough. Usually the patient also needs to be artificially ventilated at this time.
Blood poisoning: course of disease and prognosis
The course of blood poisoning is usually always the same: bacteria enter the bloodstream from somewhere in the body and spread through the bloodstream (bacteremia). If the body cannot limit the infection, sepsis occurs. Without treatment, the fight against the pathogens that cause blood poisoning expands more and more until finally damage to vessels and organs occurs (severe sepsis). The speed of progression depends on the triggering pathogen, the age of the patient and the performance of his immune system.
In the further course of sepsis, cardiovascular failure may occur. Then the blood supply to vital organs is no longer guaranteed and one speaks of septic shock. The earlier you start treatment, the better the chances of being completely cured. Organ damage often results in lifelong damage – for example, limited or failed kidney function, which makes lifelong dialysis (blood washing) necessary.
In some patients, blood poisoning cannot be successfully treated and sepsis leads to death. Roughly speaking, the mortality risk of sepsis increases by about one percent per hour in which the affected person is not adequately treated. After one day without treatment, the risk is already 24 percent. In severe sepsis with organ damage, 47 percent of patients do not survive the disease. In the case of septic shock, as many as 60 percent die of circulatory failure due to blood poisoning.
Risk of consequential damages
Many patients still suffer from late effects of blood poisoning after discharge from hospital, such as nerve damage (polyneuropathies), muscle weakness or post-traumatic stress, as well as depression. (microscopic nerve damage)
The consequences of blood poisoning can best be averted if those affected inform their doctor early on when symptoms appear. This is especially true for people who are in hospital or nursing homes, for immunocompromised patients and patients who have just undergone surgery. These patient groups should inform their doctor immediately in case of fever, chills, shortness of breath and/or dizziness.
Especially in hospitals, prevention is also an important topic. Through hygiene measures, good wound care and consistent protection of immunocompromised patients, the development of blood poisoning can be avoided in many cases.