Mediastinitis in Emergency Medicine 

Updated: May 29, 2019
Author: Feras H Khan, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD 

Overview

Background

Mediastinitis is an infection involving the mediastinum. It is a surgical emergency with a high mortality rate. Mediastinitis may begin primarily from structures in the mediastinum (often as a result of iatrogenic injury) or may result from an infection extending downward from the oropharynx, in which case it is called descending necrotizing mediastinitis (DNM).

Pathophysiology

The mediastinum is a sterile space, so infection results from disruption of normal mucosal and tissue barriers. This usually occurs either via (1) direct injury (usually iatrogenic) to adjacent structures such as the esophagus, trachea, bronchi, or sternum or (2) extension of cervicopharyngeal infections.

Direct injury

Direct mediastinal injury is the most common cause of mediastinitis in developed nations. This may be due to trauma (eg, motor vehicle accident [MVA], swallowed fish bone), Boerhaave syndrome, neoplasm, cardiothoracic surgery, upper endoscopy, bronchoscopy, tracheal or esophageal dilatation, or even endotracheal intubation. See Esophageal Perforation, Rupture and Tears for more detail on this subject.

Infectious extension

When infection extends from the head and neck downward into the mediastinum, the condition is referred to as descending necrotizing mediastinitis. The spread downward is facilitated by gravity, breathing, and negative intrathoracic pressure.[1] It is necrotizing, as the infection is often polymicrobial in etiology with gas-producing organisms. This is the most lethal form of mediastinitis.

Odontogenic infection is the most common cause of descending necrotizing mediastinitis, but pharyngeal abscess, sinusitis, and other ENT infections may also be sources.[2] This type is particularly prevalent in developing nations, where poor access to care leads to delayed diagnosis and treatment of ENT infections.

Because cervicomediastinal spaces contain loose areolar tissue with poor vascularization and few defensive mechanisms, pathogens may easily spread across fascial planes. For this reason, any cervical infection may involve the entire mediastinum.[3] The potential spaces that can allow infections from the head or neck to enter the mediastinum are discussed below.

Carotid space

The carotid sheath is a thick, matted, fibrous investment over the main longitudinal vessels of the neck. Lymph nodes are contained within the sheath, and infection in these nodes has the potential to spread downward into the mediastinum. The carotid sheath extends from the arch of the aorta to the base of the skull.

Prevertebral space

This space is bounded anteriorly by the prevertebral fascia, which overlies the prevertebral muscles in the neck. The prevertebral fascia extends from the base of the skull to the lower limit of the longus colli muscle, which is approximately at the level of T3 vertebra.

"Danger" space

This potential space lies between the alar and prevertebral fasciae. It is patent from the skull base to the diaphragm. Its upper part is the retropharyngeal space, which lies between the prevertebral fascia and the buccopharyngeal fascia on the outer surface of the pharynx. Lymph nodes are present in this space. The lower part of this potential space extends behind the esophagus, through the superior mediastinum, and into the posterior mediastinum. Seventy percent of cases of descending necrotizing mediastinitis occur in this space.[4]

Other sources

Mediastinitis may also result from direct extension from an adjacent source of infection, including osteomyelitis of the sternoclavicular junction. Pulmonary infections may also extend into the mediastinal space. Mediastinitis may also result from extension of granulomatous disease from mediastinal lymph nodes.

Pathogens

Mediastinitis is often a mixed infection, with facultative and strict anaerobes acting together. Obligate anaerobes usually outnumber facultative organisms by 10:1. Streptococcus species are the most common facultative organisms, while Bacteroides species are the most common strict anaerobes. Other organisms implicated include Staphylococcus, Escherichia coli, Peptostreptococcus, Fusobacterium, Haemophilus influenzae, Enterobacter cloacae, Histoplasmosis, Tuberculosis, and Pseudomonas aeruginosa.

Case reports have also identified Eikenella corrodens and species of Prevotella, Stenotrophomonas, Propionibacterium, Candida, Aspergillus, and Salmonella as responsible pathogens.[3, 5] As the incidence of iatrogenic mediastinitis rises compared with infections acquired outside the hospital, methicillin-resistant Staphylococcus aureus (MRSA) infections become a cause for great concern.[6]

Epidemiology

Frequency

United States

Esophageal rupture is currently the most common cause of mediastinitis. Descending necrotizing infection is relatively rare in the era of antibiotic use.

International

In developing countries, mediastinitis still is a common devastating potential complication of head and neck infections.

Mortality/Morbidity

Morbidity is significant for a mean hospital length of stay greater than 1 month, as well as a long period of outpatient recovery.[3]

Data suggest that mediastinitis has an overall lifetime mortality rate of 19%-47%; however, a review by Ridder et al suggests an improved mortality of 11.1%.[3]

Studies of descending necrotizing mediastinitis in the last decade indicate mortality rates ranging between 11.1% and 34.9%.[3]

Mortality likely has improved secondary to the widespread use of antibiotics and improved oral hygiene.[3]

In the presence of comorbid conditions, the mortality rate among patients presenting with established infections may be as high as 67%.

Race

Age and risk factors are better predictors for the development of mediastinitis than race.

Sex

The prevalence of mediastinitis is higher among males than females, with a male-to-female ratio of 6:1.

Age

Most persons who develop mediastinitis are in their third to fifth decades of life; however, it can occur in all age groups, with documented mediastinitis in patients as young as 2 months and as old as the eighth decade of life.

Risk Factors

Risk factors associated with cardiac surgery include chronic obstructive pulmonary disease (COPD), obesity, and reoperation.[7]

Prognosis

Early diagnosis and aggressive therapy seem to provide the best chance for recovery.

Despite vast improvements in IV antibiotics, critical care medicine, and CT imaging in the last 30 years, mediastinitis still carries a high mortality rate.[4]

 

Presentation

History

Most patients with mediastinitis have experienced symptoms for a few days before presentation to the emergency department (ED). Occasionally, patients present with a fulminant course and symptoms that have lasted only a few hours.

Common symptoms in patients with mediastinitis include the following:

  • History of an upper respiratory tract infection, recent dental infection (common), or thoracic surgery/instrumentation[8]

  • Fever, chills

  • Pleuritic, retrosternal chest pain radiating to the neck or interscapular pain

  • Shortness of breath

  • Cough

  • Sore throat

  • Swelling in the neck

  • Odynophagia

  • Confusion

History may be significant for recent endoscopy, bronchoscopy, intubation, surgery, thoracic malignancy, or consumption of fish or chicken bones.

Some patients are at an increased risk for mediastinitis. Obtaining the patient's medical history, which should include explicit questions about diabetes, possible immunocompromise (eg, malignancy/chemotherapy, HIV, autoimmune disease), and drug abuse, is very important.

Physical

A complete examination of the chest, head, and neck, including the oral cavity, is essential. Such an examination may yield the following findings:

  • Ill appearance

  • Fever

  • Tachypnea

  • Tachycardia

  • Signs of sepsis disproportionate to the rest of the history and examination

  • Edema of the neck and face

  • Trismus

  • Evidence of cervical or oropharyngeal abscess

  • Crepitus of chest or neck

  • Stridor

  • Hamman sign (crunching sound upon auscultation of the heart)

Causes

Causes of mediastinitis may include the following:

  • Iatrogenic mishap following esophageal instrumentation (eg, upper endoscopy, esophageal dilatation, transesophageal biopsy, esophageal surgery)

  • Iatrogenic mishap following tracheal instrumentation (eg, bronchoscopy, tracheal dilatation, transbronchial biopsy)

  • Esophageal rupture

  • Esophageal foreign body (eg, fish bone)

  • Mediastinitis may present as a delayed infection following thoracic surgery, such as coronary artery bypass

Primary cervicopharyngeal infections may include the following:

  • Pharyngitis

  • Tonsillitis

  • Sinusitis

  • Retropharyngeal abscess

  • Dental infections

  • Sialadenitis

  • Suppurative thyroiditis

Endotracheal intubation

Perforation of the hypopharynx or esophagus during intubation may cause mediastinitis. This is particularly likely to occur if the intubation was difficult and required the use of a rigid stylet.

Patients usually develop symptoms and signs in the immediate postintubation period, although delayed presentations are reported. Consider this complication if a patient's condition deteriorates in the postintubation period and if signs of sepsis or cardiovascular compromise are observed.

Fibrosing mediastinitis

This very rare entity is an excessive fibrotic reaction in the mediastinum. It is usually observed as a result of histoplasmosis or other granulomatous disease.

Patients usually present with symptoms of compression or occlusion of mediastinal structures. Presenting symptoms include cough, superior vena caval obstruction, shortness of breath, chest pain, or hemoptysis.

Onset is usually insidious.

Other causes

Tuberculous mediastinitis may occur after the rupture of a tuberculous lymph node into the mediastinum. Diagnosis may be difficult because some patients initially have few symptoms or signs. Radiographic findings may indicate a mediastinal mass, and the diagnosis may not be made until further investigations, including an MRI, are completed.

Fungal infection, usually caused by Candida species, is observed after cardiothoracic surgery in 0.3% of cases.

Mediastinitis has been described as a complication of laparoscopic cholecystectomy.

Complications

Complications of mediastinitis may include the following:

  • Death

  • Pericarditis

  • Sepsis

  • Multiorgan system failure

  • Adult respiratory distress syndrome

  • Cardiac tamponade

  • Empyema

  • Vascular thrombosis

  • Arterial hemorrhage via erosion of infection[2]

 

DDx

 

Workup

Laboratory Studies

The diagnosis of mediastinitis is often a clinical one. No single laboratory investigation can confirm the diagnosis; however, studies that may help in the diagnosis of mediastinitis include the following:

  • Inflammatory markers (white blood cells [WBC], C-reactive protein [CRP], erythrocyte sedimentation rate [ESR], and procalcitonin) are often elevated.

  • Metabolic measurements are often normal but may reveal anion gap, hyponatremia, hypoglycemia or hyperglycemia, or hypoproteinemia

  • Blood cultures

  • Swab from any site of infection

It is important to notify the laboratory of the possible presence of anaerobic organisms and the strong possibility of mixed growth, since many laboratories routinely report only a single predominant organism. Close coordination with the laboratory is vital to optimize the antibiotic regimen.

Imaging Studies

Plain-film radiography

Soft tissue radiography of the neck may show widening of the precervical and retropharyngeal soft tissues.

Plain-film chest radiographs may show widening or haziness of the mediastinum or mediastinal air.

The lateral chest radiograph may show an anterior bulge on the posterior wall of the trachea.

Pleural effusions and lower lobe consolidation are not unusual findings.

It is important to note that plain films may appear normal and cannot by themselves exclude the diagnosis.

Chest CT scanning

Chest CT scanning is the imaging modality of choice for the diagnosis of mediastinitis.

If there is a concern for descending infection, it should be paired with a neck CT scan.

Chest CT scanning can provide accurate information regarding both the presence and extent of descending necrotizing mediastinitis (DNM), helping guide the mode of surgical approach for drainage. Chest CT scanning can also be used to monitor progress after treatment.[1]

Head and neck CT scanning

In the case of descending necrotizing mediastinitis, head and neck CT scans may demonstrate abnormalities while the chest radiograph still appears normal.

Abscess and soft tissue swelling are usually visible.

Neck CT scanning can help with planning the surgical approach.

MRI

Use of MRI to confirm the diagnosis of mediastinitis is becoming more common but continues to be reserved more for children to limit radiation and those with impaired kidney function.[3] It should be noted that mediastinitis is a time-sensitive diagnosis - if MRI is utilized, it should not be delayed.

Mediastinitis due to esophageal perforation is shown in the radiograph below. CT of the same patient follows.

Chest radiograph of a patient presenting with medi Chest radiograph of a patient presenting with mediastinitis secondary to esophageal perforation by a chicken bone. Image courtesy of Mark Silverberg, MD, FACEP, and Rafi Israeli, MD.
Chest CT of same patient showing gas-filled medias Chest CT of same patient showing gas-filled mediastinal abscess and widened esophagus. Image courtesy of Mark Silverberg, MD, FACEP, and Rafi Israeli, MD.
 

Treatment

Prehospital Care

Mediastinitis may result in airway compromise. Protection of the airway is vital. Since patients may present in septic shock, adequate volume resuscitation is essential.

Emergency Department Care

Ensure an adequate airway. Do not allow a patient who is potentially unstable to be placed into the CT scanner without ensuring that the airway is adequately protected. Intubation may be difficult because of soft tissue swelling. Fiberoptic assistance may be required, and an emergent cricothyrotomy or tracheostomy may become necessary. In addition to the usual complications of intubation, it may be further complicated by trauma to the retropharyngeal wall, laryngospasm, or aspiration of purulent material.

Antibiotic therapy should be initiated without delay.

Fluid resuscitation and management of sepsis are essential.

The key component of ED management is expeditious diagnosis. Mediastinitis may present a confusing clinical picture and may be mistaken for entities such as pneumonia, acute coronary syndrome, pharyngitis, or isolated pharyngeal abscess, among others. A high index of suspicion is required, particularly in patients with findings of a concomitant cervicopharyngeal infection or with a history of thoracic, esophageal, or tracheal instrumentation or malignancy. Prompt diagnosis and surgical treatment is associated with improved survival.

Consultations

Immediately make arrangements for surgical consultation. Extensive and aggressive debridement of necrotic tissues with exploration of all mediastinal fascial spaces may be required. Controversy exists about whether the cervical approach or the transthoracic approach is best. Some physicians support a combination of the two approaches. In some case series, the combination approach has been associated with a lower mortality rate. Depending on the resources available, consultations may include otorhinolaryngology, cardiothoracic surgery, and general surgery.

The necessity for extensive drainage may mandate the transfer of some patients to a tertiary referral center.

Further Inpatient Care

As for any abscess, the essential management of this condition involves prompt and extensive surgical debridement.[9]

The use of hyperbaric oxygen for this condition is controversial.

Recent studies have looked at the use of intravenous immunoglobulins for mediastinitis, particularly when the condition arises as a complication of cardiothoracic surgery.

Broad-spectrum antibiotics are necessary. Antibiotics should be capable of treating aerobes, anaerobes, and gram-positive and gram-negative infections.

Lengthy hospitalization (≥1 month) is common.

Transfer

Optimal treatment of this disease requires extensive surgical debridement. This may require the services of cardiothoracic surgeons and otorhinolaryngologists and may necessitate a transfer if these services are not available.

Patients with mediastinitis often require highly skilled intensive care. Some patients may require referral to a tertiary care center if these resources are not available at the presenting hospital.

 

Medication

Medication Summary

Because mediastinitis is usually a mixed growth infection, wide antimicrobial coverage is required. The cause of infection should be determined. Extension of S aureus osteomyelitis should be managed differently from an esophageal rupture; however, in the absence of a source and definitive microbiological data, broad-spectrum therapy is indicated. Antibiotic administration should not be delayed once the diagnosis is suspected. Combinations such as piperacillin-tazobactam plus vancomycin or vancomycin plus a fluoroquinolone and clindamycin should be used. An aminoglycoside may be added to broaden gram-negative coverage.

In general, S aureus, including MRSA, should be covered initially. In addition, coverage should include gram0negative bacteria, including P aeruginosa.

Antibiotics

Class Summary

Therapy must cover all likely pathogens in the context of the clinical setting.

Ceftriaxone (Rocephin)

Third-generation cephalosporin that has broad-spectrum gram-negative activity, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. By binding to one or more of the penicillin-binding proteins, it arrests bacterial cell wall synthesis and inhibits bacterial growth.

Clindamycin (Cleocin)

Lincosamide that is useful treatment of serious skin and soft tissue infections caused by most staphylococcal strains. Effective against aerobic and anaerobic streptococci, except enterococci. Inhibits bacterial protein synthesis by inhibiting peptide chain initiation at the bacterial ribosome where it preferentially binds to the 50S ribosomal subunit, causing bacterial growth inhibition.

Imipenem-cilastatin (Primaxin)

Used for treatment of multiple organism infections in which other agents do not have wide spectrum coverage or are contraindicated because of their potential for toxicity.

Metronidazole (Flagyl)

Active against various anaerobic bacteria and protozoa. Appears to be absorbed into the cells and the intermediate metabolized compounds that bind DNA are then formed and inhibit synthesis, causing cell death.

Gentamicin (Garamycin)

An aminoglycoside antibiotic effective against Pseudomonas aeruginosa,Escherichia coli,Proteus,Klebsiella, and Staphylococcus species.

Numerous dosing regimens are available, and they are adjusted based on creatinine clearance and changes in the volume of distribution. The dose of gentamicin may be given IV or IM.

Piperacillin and tazobactam sodium (Zosyn)

Antipseudomonal penicillin plus beta-lactamase inhibitor. Inhibits the biosynthesis of cell wall mucopeptide and is effective during the stage of active multiplication. This medication has a broad antimicrobial spectrum that is effective again most oral, respiratory, and GI bacterial pathogens. Used in concert with gentamicin, strong anti-gram-negative activity occurs.

Ampicillin and sulbactam (Unasyn)

Drug combination of beta-lactamase inhibitor with ampicillin. Interferes with bacterial cell wall synthesis during active replication, causing bactericidal activity against susceptible organisms.

Vancomycin (Vancocin)

Inhibits cell wall synthesis. Accomplished by binding to carboxyl units on peptide subunits containing free D-alanyl-D-alanine.

Effective against methicillin-resistant S aureus.