Septic shock is a life-threatening condition that happens when your blood pressure drops to a dangerously low level after an infection. Any type of bacteria can cause the infection. Fungi such as candida and viruses can also be a cause, although this is rare.
At first the infection can lead to a reaction called sepsis. This begins with weakness, chills, and a rapid heart and breathing rate. Left untreated, toxins produced by bacteria can damage the small blood vessels, causing them to leak fluid into the surrounding tissues. This can affect your heart’s ability to pump blood to your organs, which lowers your blood pressure and means blood doesn’t reach vital organs, such as the brain and liver.
Pathophysiology Septic Shock
The pathogenesis of septic shock is not completely understood. An inflammatory stimulus (eg, a bacterial toxin) triggers production of proinflammatory mediators, including tumor necrosis factor (TNF) and interleukin (IL)-1. These cytokines cause neutrophil–endothelial cell adhesion, activate the clotting mechanism, and generate microthrombi. They also release numerous other mediators, including leukotrienes, lipoxygenase, histamine, bradykinin, serotonin, and IL-2. They are opposed by anti-inflammatory mediators, such as IL-4 and IL-10, resulting in a negative feedback mechanism.
Initially, arteries and arterioles dilate, decreasing peripheral arterial resistance; cardiac output typically increases. This stage has been referred to as warm shock. Later, cardiac output may decrease, blood pressure falls (with or without an increase in peripheral resistance), and typical features of shock appear.
Even in the stage of increased cardiac output, vasoactive mediators cause blood flow to bypass capillary exchange vessels (a distributive defect). Poor capillary flow resulting from this shunting, along with capillary obstruction by microthrombi, decreases delivery of oxygen and impairs removal of carbon dioxide and waste products. Decreased perfusion causes dysfunction and sometimes failure of one or more organs, including the kidneys, lungs, liver, brain, and heart.
Coagulopathy may develop because of intravascular coagulation with consumption of major clotting factors, excessive fibrinolysis in reaction thereto, and more often a combination of both.
Causes of Septic Shock
Sepsis can start with almost any type of infection, ranging from minor infections like an abscessed tooth or athlete’s foot, to serious infections like meningitis, which affects the membranes of the brain and spinal cord.
The infection most commonly begins with one of the following:
- Pneumonia, an infection of the air sacs in the lungs
- Urinary tract infection
- Bacterial infection in a cut or wound
- Gastrointestinal tract infection, such appendicitis or E. coli
Septic shock can also be a complication of fungal infections, such as yeast infection, or viral infections, such as the flu or COVID-19.
You can’t pass sepsis along to someone else, but you can spread infections that may lead to sepsis and septic shock.
What are the risk factors?
Certain factors such as age or prior illness can put you at greater risk for developing septic shock.
The people who are more vulnerable to sepsis include newborns, older adults, pregnant people, and those with suppressed immune systems due to HIV, autoimmune conditions, cirrhosis of the liver, kidney disease, and cancer.
The following factors could also make a sepsis diagnosis – and possibly septic shock – more likely:
- Recovering from surgery or being in the hospital for a long time
- Living with diabetes
- Being exposed to devices like intravenous catheters, urinary catheters, or breathing tubes, which can introduce bacteria into the body
- Taking immunosuppressant drugs
Septic shock can affect any part of the body, including the heart, brain, kidneys, liver, and intestines. Symptoms may include:
- Cool, pale arms and legs
- High or very low temperature, chills
- Little or no urine
- Low blood pressure, especially when standing
- Rapid heart rate
- Restlessness, agitation, lethargy, or confusion
- Shortness of breath
- Skin rash or discoloration
- Decreased mental status
Septic Shock Complications
One of the most serious septic shock complications is organ damage. In some cases, the damage may only be temporary. For example, a person in septic shock may develop acute kidney injury. The kidneys are not able to filter out the toxins from the blood. If this occurs, the patient may need dialysis, a procedure where a machine acts as the body’s kidneys to cleanse the blood. As the body heals, the kidneys may begin functioning again. But in many cases, organ damage is permanent.
Another serious septic shock complication is tissue death (gangrene) that leads to amputations. Not only does hypotension reduce the blood flow to the less vital parts of the body, like the feet and hands, people with severe sepsis or septic shock can develop tiny blood clots in the blood vessels. These clots can block blood that tries to reach the area, resulting in tissue death.
If too much of the tissue has died, a surgeon must remove it to prevent the dead tissue from spreading. Some septic shock survivors must have the tips of fingers and toes removed, while others lose one or both legs, or even all four limbs.
Accurate statistics regarding sepsis-related amputations are not easily available, but a study presented in 2019 looked at 1.5 million sepsis survivors in the United States and the researchers found that one out of every 100 survivors had an amputation within 90 days of their sepsis diagnosis. Most amputations were of the lower limbs.
There are physical changes that a healthcare provider can check for to help diagnose septic shock. These include:
- Fever, a body temperature above 100.4 degrees F
- Hypothermia, a body temperature below 96.8 degrees F
- Low blood pressure
- High heart rate
- Difficulty breathing
In addition, your healthcare provider may run blood and urine tests to check for signs of infection and determine the type. Certain tests can reveal whether or not your organs are functioning as they should.
A critical tool for diagnosing sepsis in its earliest stages is the procalcitonin (PCT) blood test. PCT is a protein that rapidly increases in the blood as a bacterial infection spreads. Doctors can use the PCT test to see how widespread an infection is.
The PCT test is also important because it shows doctors whether or not antibacterial drugs are an appropriate treatment. While bacterial infections cause high PCT results, viral and fungal infections cause a very low PCT count.
You may also need imaging tests, such as X-rays or computed tomography (CT scans), especially if the source of infection is unclear.
Treating septic shock
Sepsis and septic shock are medical emergencies and must be treated immediately.
It’s likely you’ll be admitted to an intensive care unit (ICU) for urgent treatment and to carefully monitor your progress. In some cases treatment may begin in the emergency department.
To help you breathe more easily, you’ll be given oxygen through a face mask, a tube inserted into your nose, or an endotracheal tube inserted into your mouth. If you have severe shortness of breath, a mechanical ventilator may be used.
Increasing blood flow
You’ll probably be given fluids directly into a vein. This will help raise your blood pressure by increasing the amount of fluid in your blood.
To increase the blood flow to your vital organs, such as your brain, liver, kidneys and heart, you may be prescribed inotropic medicines or vasopressors.
Inotropic medicines (inotropes), such as dobutamine, stimulate your heart. They increase the strength of your heartbeat, which helps get oxygen-rich blood to your tissues and organs, where it’s needed.
These medicines will cause your blood vessels to narrow, increasing your blood pressure and the flow of blood around your body. This will allow your vital organs to start functioning properly.
Antibiotics are often used to treat the associated bacterial infection. The type of antibiotic used depends on the type of bacterial infection and where in the body the infection started.
You may be started on antibiotics immediately to increase your chances of survival. Initially, two or three types of antibiotics may be used. The most effective type of antibiotic can be used once the bacterium responsible for the infection is identified.
In severe cases of sepsis or septic shock, the large decrease in blood pressure and blood flow can kill organ tissue. If this happens, surgery may be required to remove the dead tissue.
There are a few steps that people can take to reduce their risk of developing sepsis and septic shock:
- Get regular vaccinations against viral infections that may cause sepsis.
- Practice good hygiene.
- Care for and clean any open or gaping wounds.
- Follow medical advice on managing bacterial infections.
- Treat fungal and parasitic infections as soon as symptoms appear.
- Control diabetes, if relevant.
- Avoid smoking.
Hand-washing tips for people with compromised immunity
People with compromised immune function should take extra care when washing their hands.
The following steps can assist in proper hand washing:
- Remove rings and watches when possible to clean the areas of skin beneath them.
- Add warm, running water to the skin on the hands and wrists.
- Lather liquid soap onto the hands, being sure to include the skin between the fingers.
- Spend 10–15 seconds washing the hands.
- Use a towel to turn off the tap to prevent recontamination.