What Is Mediastinitis?

Did you know that an infection in the chest cavity is a different concept than a chest infection which fundamentally stands for the infection of your lungs or airways?

Mediastinitis is inflammation or infection involving the space within the chest cavity. Although there is treatment available, this condition can be life-threatening if not managed on time and properly.

You can increase your knowledge about this condition by reading our article, where you can find information about important aspects of Mediastinitis.

Introduction

Mediastinitis is a serious condition involving an infection or inflammation of various important structures within an enclosed space called the mediastinum. The mediastinum is found between the thoracic cavity (which is near the lungs). Although it is a rare condition, it should always be considered as a potential diagnosis due to the fact that it might cause severe complications and potentiallydeath. Given the severity of the consequences, mediastinitis requires immediate treatment.¹

Mediastinitis can be acute with a sudden onset or chronic with a gradual onset. The leading causes of mediastinitis are usually complications after chest surgery or a tear in your food pipe (the oesophagus). Despite effective prevention and treatment strategies, mediastinitis following surgery still has  significant prevalence ranging between 0.25% and 5%. This means it can affect 25 to 500 individuals in a population of 10,000.²

Anatomy of the mediastinum

Behind our chest wall, we have a structure called the thoracic cavity. Within the thoracic cavity, we have 3 compartments: 2 pleural cavities that house our lungs on each side and the mediastinum in the middle. 

The mediastinum runs lengthwise from the thoracic inlet to the upper surface of our diaphragm. Despite no existing borders, mediastinum can artificially be divided into 4 compartments: superior (upper), anterior (front), middle, and posterior (back).

The mediastinum is the house for vital structures, including our heart. Other important structures include our food pipe, part of large blood vessels connected to our heart and our lungs, our windpipe and large airways, nerves supplying our internal organs, and lymph glands. Furthermore, our mediastinum functions as a protected pathway for important structures travelingfrom our neck to our tummy. 

Understanding the structures lying inside your mediastinum can help you understand the importance of mediastinitis. Due to the fact that it accommodates vital organs and vessels, inflammation or infection inside your mediastinum can be very dangerous and life-threatening.³

Causes of mediastinitis

There are many causes of mediastinitis. Infectious or non-infectious conditions can be the cause of mediastinitis by breaching the integrity of the mediastinal structures.¹

Infections

The spread of an infection from your neck, throat or teeth to your mediastinum can cause acute infection, abscesses, or sepsis (the body’s extreme reaction to an infection). This particular form of mediastinitis is called descending necrotising mediastinitis and it is mainly caused by different kinds of bacteria. 

Histoplasmosis (a type of fungal infection) and tuberculosis can cause a fibrosing mediastinitis, which develops more gradually. However, a more widespread form of fibrosing mediastinitis is linked with autoimmune conditions.¹

Non infectious causes

The form of mediastinitis that happens following a surgical procedure is called postoperative mediastinitis. It commonly occurs after sternotomies (a procedure to separate your breastbone) and thoracic surgeries. The underlying mechanism behind this is the introduction of infection during the surgery or of the surgical wound. This type of mediastinitis is one of the most common causes.

Another common cause of mediastinitis is due to a rupture in your food pipe or windpipe after an  endoscopic procedure or having Boerhaave syndrome (rupture in the food pipe due to forceful vomiting).

Other less common causes of mediastinitis include injury due to direct trauma, the spread of lung infection and pancreatitis (inflammation of pancreas).¹

Fibrosing mediastinitis (FM) is a type of mediastinitis characterised by the excessive production of fibrous tissue (dense connective tissue) inside the mediastinum. Several conditions can cause FM including:

• Fungal infections
• Tuberculosis
• Certain autoimmune conditions such as sarcoidosis
• Radiation therapy to your chest

On occasion, no specific reason can be found as a cause of FM. In this case FM is named as idiopathic.⁴

Symptoms and clinical presentation

Clinical presentations of mediastinitis vary from mild cases to critically ill patients. In addition, gradual onset of symptoms can be seen in patients with chronic mediastinitis.²

Acute mediastinitis

Signs and symptoms of acute mediastinitis include:^1,2

• Sudden severe chest pain
• Chills
• Fever
• Oozing from the surgical wound (if the cause is due to surgery)
• Delayed wound healing after surgery
• Shortness of breath
• Difficulty swallowing
• Tachycardia (fast heartbeat)
• Low blood pressure 

Chronic mediastinitis

Although chronic mediastinitis may not initially cause symptoms, patients with fibrosing mediastinitis may present with:⁵

• Chest pain
• Cough (may include blood sometimes)
• Shortness of breath
• Prominent veins on the neck and upper chest region
• Facial swelling
• Difficulty swallowing
• Hoarseness of voice
• Tiredness

As the disease progresses, symptoms become related to involvement and obstruction of the structures inside the mediastinum.⁵ 

Diagnosing mediastinitis

When diagnosing mediastinitis, your doctor will take a detailed medical history, perform a physical examination, and order some imaging and laboratory tests.¹

Medical history and physical examination

While taking your medical history, the doctor might ask you some questions including recent surgeries or infections, past medical history, travel and social history to determine any cause or risk factors for mediastinitis.

On physical examination, your doctor might find unstable chest bone, an oozing wound, pain, and tenderness. If descending necrotising mediastinitis is suspected, redness and crepitus may be found on your neck or chest during the examination.¹

Imaging tests

Although a chest X-ray might be helpful in certain cases of mediastinitis, it is usually not sufficient to demonstrate the extent of the disease. Compared with an X-ray, CT and MRI are more successful in diagnosing mediastinitis. In fact, contrast-enhanced CT (a CT scan with the use of a special dye) is acknowledged as the gold standard for diagnosis.^1,2

Laboratory tests

Your doctor might order some blood tests to check the count of your white blood cells as well as some inflammatory markers such as C-reactive protein (CRP) and procalcitonin, which are usually found to be elevated. 

A blood culture sample to identify any microorganisms in your bloodstream might also be ordered as part of the investigations.¹

Treatment and management

In case of suspected mediastinitis, your airway, breathing, and circulation will be assessed as the first step to ensure you are stable and not in need of life support.¹

Treatment and management options depend on the underlying cause, form and severity of the condition. 

Antibiotics and antifungal medications

Early administration of broad-spectrum antibiotics is a crucial step in the management of mediastinitis. Antibiotics are typically given intravenously (through the veins) and may be changed later based on the culture results.^1,6

A fungal infection might be the reason when there is no response to antibiotics treatment. In that case, antifungal medications may be administered.⁶

Surgical interventions

Without surgical drainage of the infection, antimicrobial therapy alone is not effective to clear the infection. There are various surgical approaches ranging from minimal to maximal procedures. The type of the approach will depend on the severity and extent of mediastinitis. The need for a subsequent surgery will be decided by imaging scans, blood tests and reassessment of the clinical picture.^1,6

Treatment for fibrosing mediastinitis

There is no consensus on standard treatment strategy for fibrosing mediastinitis. Immunosuppressive drugs, corticosteroids, or antifungal medications are mostly used options as there are limited options for medication therapy. 

Surgical treatment may be considered for patients with symptoms. Surgery aims to relieve the symptoms by opening up the airway or boosting the blood flow of the affected structure.¹

FAQs

What are the complications of mediastinitis?

Given the fact that mediastinitis affects crucial structures, it may cause various significant and even life-threatening complications including:^1,6

• Pericarditis (inflammation of the lining around the heart)
• Repeated lung infections
• Thoracic empyema (collection of pus between the layers of the lining around the lungs)
• Sepsis 
• Airway obstruction
• Severe bleeding or coughing up blood
• Right-sided heart failure
• Multiorgan failure
• Complications related to surgical procedures

How can I prevent mediastinitis?

Due to the fact  mediastinitis occurs as a result ofchest surgery or endoscopy, certain measures prior to the procedures may help decrease the risk of developing mediastinitis. Such measures to reduce the incidence of surgical site infections include:²

• Screening for carriage of multiresistant organisms 
• Antimicrobial prophylaxis (treatment given prior the procedure to prevent infection) 
• Preliminary cleanse of the skin prior the surgery
• Following appropriate surgical technique and wound management.

Preventing infections or treating them early can also help prevent acute mediastinitis. 

Who is at risk of mediastinitis?

Certain risk factors increase your risk of developing acute mediastinitis following a surgery. Patient-related risk factors include:

• Old age
• Obesity
• Diabetes mellitus
• Smoking
• Heart failure
• Kidney failure
• Peripheral vascular disease
• Staphylococcus aureus colonisation

 Procedure-related risk factors include the length of the surgery and repeat surgery.

Having an impaired immune system, steroid use, smoking, and delayed diagnosis increase your risk of developing descending necrotizing mediastinitis.⁷

Summary

Mediastinitis is a serious infection or inflammation of the mediastinum, which is the space within the chest cavity, housing vital structures like the heart and airways. It can be acute or chronic. Also, it is most commonly caused by complications after chest surgery or oesophageal tears. Early diagnosis and treatment are crucial as it can prevent severe complications. Symptoms include chest pain, fever, difficulty swallowing, and shortness of breath. Treatment includes antimicrobial therapy, and surgical intervention. Managing risk factors and early treatment are key to addressing this life-threatening condition. If you think you or anyone around you might have mediastinitis, it can be life-saving to seek medical advice without any delay.