Multiple organ dysfunction syndrome (MODS), also known as multiorgan failure, is a disorder in which two or more organ systems are not working correctly, usually because of a complex cascade of events initiated by an illness, injury, or severe infection. MODS is a severe illness in which someone can die if the dysfunction is not treated immediately. Due to a high risk of death, people with MODS are typically cared for in an intensive care unit where healthcare providers can potentially reverse the organ damage.
This article discusses multiple organ dysfunction syndrome, including its causes, symptoms, treatment, and prevention.
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Table of Contents
Causes
Any significant illness, injury, or infection can result in MODS. While the exact mechanisms that lead to MODS are not well understood, experts think widespread inflammation and decreased blood flow work together to cause organ damage.
People suffer multiple “hits” during a severe illness. The first is the inciting event, such as a major motor vehicle accident or massive heart attack. The second is when the immune system overreacts to fix the problem. Finally, a third hit can occur if a person needs major surgery or develops an infection after the initial insult.
Specific disorders are more likely to lead to this dangerous cascade of events and eventual organ dysfunction. Examples of these severe illnesses include:
These conditions lead to significant changes within the immune and hematologic systems that affect other organs.
MODS is not only due to the initial hit itself but also results from a cascade of events involving many or all organ systems. People experience decreased blood flow and oxygen, leading to damage.
An overwhelming immune response that leads to free radical generation is also involved. Free radicals are reactive molecules generated in the body and can alter fats, proteins, and DNA to trigger disease.
Other individual factors that affect the development of MODS include:
People without other health problems often survive MODS.
Risk of Death From MODS
During a severe illness, if a person has two failing organ systems, their likelihood of dying can be 20% to 50%. If a person has dysfunction of four organ systems, their likelihood of death can be 60% to 100%.
Symptoms
The severity of MODS is determined by the amount of dysfunction in six main organ systems. These systems include:
- Respiratory system
- Cardiovascular system
- Renal system
- Hepatic system
- Hematologic system
- Neurologic system
There are several different scoring systems used to determine the severity of MODS. To create a severity score, each organ system is evaluated and used to predict a person’s likelihood of recovery vs. death. Healthcare providers monitor an organ system through a person's symptoms and laboratory testing.
Respiratory (Lungs)
People with MODS can develop difficulty breathing due to lung damage. Often people need to be placed on a ventilator to help them breathe.
However, although mechanical ventilation helps treat lung problems, it can sometimes cause lung injury, worsening the overall disease process. As lung dysfunction continues, the lungs fill up with fluid and start to develop scar tissue.
The worst type of lung injury found in people with MODS is acute respiratory distress syndrome (ARDS). Once ARDS sets in, people have difficulty maintaining oxygen in the blood and have a higher risk of dying.
Cardiovascular (Heart)
The widespread inflammation associated with MODS dilates the blood vessels, slowing blood flow to tissues. This process becomes evident when a person has low blood pressure with a severe illness or injury. The vessels also become leaky, allowing fluid to collect in the tissues and skin, known as edema.
Slowed blood flow leads to clotting in some body areas, worsening the function of already damaged organs. These cumulative effects are particularly concerning when the organ affected by the decreased blood flow is the heart.
In this scenario, the heart will not function appropriately to continue to push blood to the rest of the organ systems and body. This can be considered a "silent heart attack," which compounds the overall problem and leads to the failure of other organ systems.
Higher Risk of Death With Cardiac Dysfunction
Unfortunately, people with MODS who develop cardiac dysfunction often have a higher likelihood of dying.
Renal (Kidneys)
The renal system includes the kidneys, which help excrete toxins and fluids from the body.
Decreased blood flow can lead to kidney dysfunction. In addition, people may need dialysis to get rid of toxins and extra fluid.
The primary sign of renal dysfunction is decreased urine output.
Kidney function can also be made worse by certain medications used during the treatment of MODS.
Hepatic (Liver)
The liver's function is to get rid of toxins. It makes specific proteins necessary for other organ systems to function correctly.
People with MODS and decreased blood flow can develop liver failure. People may look yellow from hepatic dysfunction. Liver failure can lead to further imbalance inside the body.
Hematologic (Blood)
MODS is associated with a complex cascade of events that disrupt the balance of specific proteins and slow blood flow. This imbalance can simultaneously lead to bleeding and clotting.
Parts of the body are affected differently depending on the severity of MODS, the presence of previous illnesses, and the person's genetics. The person can develop bruising and color changes to the skin. They might start bleeding inside the stomach.
The most severe problem of hematologic system failure is disseminated intravascular coagulation (DIC). The syndrome becomes evident when people spontaneously bleed around catheter sites (the tubes placed for a person's resuscitation).
People with DIC have a poor prognosis. Only about half of people with DIC survive.
Neurologic (Brain)
Widespread inflammation and problems with the hematologic system lead to decreased blood flow to the brain. This, in conjunction with blood clotting, can lead to brain damage, which may cause people with MODS to have a reduced level of consciousness or be confused.
These changes can also cause various other problems, including stroke-like symptoms.
Treatment
MODS treatment is multifactorial and depends on the inciting event and type of organ damage.
- People with widespread infection and sepsis need antibiotics.
- People who develop respiratory failure need to be placed on a ventilator and sedated to rest the lungs.
- Medications called vasopressors are often required to maintain a person's blood pressure and tissue perfusion.
- People are typically treated with intravenous fluids, but healthcare providers need to delicately balance a person’s acid-base status and electrolytes when using intravenous fluids.
- Problems with the hematologic system need to be treated based on whether a person is bleeding too much or clotting too much. Sometimes people require blood or platelet transfusions.
- People with severe injuries may need surgery.
A more complex and high-tech treatment is extracorporeal organ support (ECOS). ECOS involves using a machine to extract blood from the body and process it with medications before replacing it. These systems can bypass different organs depending on the needed treatment. The most common of these systems is a hemodialysis machine that bypasses the kidneys.
Extracorporeal membrane oxygenation (ECMO) involves a machine that functions as an artificial lung. It is increasingly used as a treatment to rest the lungs and heart.
A molecular absorbent recirculating system (MARS) can support the liver.
Prevention
There is no particular medication that helps to prevent MODS. Researchers have investigated ways to treat early MODS to prevent worsening illness, but interventions can be controversial.
However, there is good evidence that healthcare providers can avoid worsening organ dysfunction by:
- Minimizing trauma to the lungs during ventilatory support
- Restricting blood transfusions until absolutely necessary
- Avoiding medications that are toxic to the kidneys
- Giving medications to prevent ulcers and bleeding in the stomach
- Giving people good nutrition
- Preventing hematologic complications by thinning the blood
Summary
Multiple organ system dysfunction (MODS) is a severe illness defined as dysfunction of at least two organ systems. MODS can affect any organ, but the primary players are the lungs, heart, kidneys, liver, brain, and blood.
There are many causes of MODS, but the general categories include major trauma, severe illness, and widespread infection. Treatment is multifaceted but centers around treating the initial insult and working to prevent severe injury to other organ systems.
A Word From Verywell
Hearing that you or a loved one is experiencing a significant emergency like MODS can be terrifying. Be assured that hospitals and healthcare providers are prepared and trained for emergency events like MODS to occur. They are very capable of preventing further trauma after an initial incident.
