Esophageal Perforation and Acute Mediastinitis



Esophageal Perforation and Acute Mediastinitis


Jason W. Smith

Christopher H. Wigfield

Robert B. Love



Esophageal Perforation


Introduction

Esophageal perforation is both a highly lethal disease and primarily a surgical problem, and has remained such since nearly 4,000 BC as documented in the Edwin Smith Papyrus. Boerhaave then recorded his classical description of spontaneous rupture of the esophagus in 1724 [1]. Recently, there has been a shift in the etiology of esophageal perforation such that iatrogenic injury from instrumentation is the most common cause of esophageal perforation accounting for 40% of cases, while trauma represents 20%, spontaneous rupture (Boerhaave’s) 15%, and tumor, foreign bodies, and operative injury collectively represent the remaining 25% of cases, leaving the two
most common causes in the modern era as endoscopy related injury and anastomotic leakage [2]. The mortality associated with perforation of the esophagus remains high despite the most modern surgical and medical care, and ranges from 10% for early diagnosis to 75% for cases with late presentation.






Figure 147.1. Zones of the mediastinum: these are identified on the left-hand side of the diagram. The superior mediastinum contains the thymic remnants, brachiocephalic veins, superior vena cava, aortic arch, trachea, phrenic nerve, vagus nerve, and the left recurrent laryngeal nerve. The anterior mediastinum contains primarily adipose and lymphatic tissue. The middle mediastinum is composed of the heart, pericardium, pulmonary trunk, aortic root, phrenic nerve, and tracheal bifurcation. The posterior mediastinum holds the descending thoracic aorta, azygos vein, esophagus, sympathetic chains, splanchnic nerves, and the thoracic duct. The right side of the diagram depicts each region of the esophagus, cervical, thoracic, and abdominal, and the injuries that occur there in decreasing order.


Esophageal Anatomy

The esophagus is a muscular tube that extends from the pharynx to the stomach and is between 23 and 27 cm in length. It has three anatomic narrowings at the upper esophageal sphincter, at the level of the aortic arch and crossing of the left mainstem bronchus, and at the lower esophageal sphincter. The wall of the esophagus is comprised of the outer longitudinal muscle and the thicker inner layer of circular muscle. The innermost layer is the epithelial mucosa of the esophagus. The blood supply to the esophagus in the cervical region is primarily derived from the inferior thyroid artery. The thoracic esophagus receives its primary blood supply from the bronchial arteries and also receives branches directly from the descending thoracic aorta. The left gastric artery and the inferior phrenic arteries supply the abdominal portion of the esophagus. These arteries form a rich submucosal network of anastomoses that permit extensive mobilization and resection without fear of devascularization. The innervation of the esophagus is primarily from the vagus. Injury to the recurrent laryngeal branch of the vagus is well known for resulting in vocal cord paralysis, but less well known is the fact that significant functional impairment also occurs in the cricopharyngeal constrictor and motility of the cervical esophagus, contributing to the risk of aspiration after such an injury.


Pathophysiology

The most common locations for perforation of the esophagus to occur are at the narrowest portions of the organ but they can and do occur at any point. The absolute narrowest area in most people is at the cricopharyngeus muscle at the level of C5–C6, which corresponds to the upper esophageal sphincter (UES). This represents the portion of the esophagus most often injured during endoscopy and the risk is increased with hyperextension of the neck and in patients with bone spurs on the anterior surface of the vertebral bodies secondary to the presence of minimal tissue in the posterior cervical compartment between the posterior wall of the esophagus and the spine. The incidence of perforation during flexible endoscopy is about 0.03%; this is markedly improved over the era of routine rigid endoscopy which carried a much higher incidence of injury in the 0.11% range. Other iatrogenic causes of injury at the UES is transesophageal echocardiography performed during cardiac surgery and has a slightly higher incidence at 0.18% and other manipulations of the hypopharynx as in endotracheal intubation or nasogastric tube placement (Fig. 147.1).

The next narrow portion is at the level of the aortic arch and left mainstem bronchus and this is a common site for foreign body obstruction and ultimate perforation. Fish and chicken bones are the most common offenders in adults, while children tend to have a much wider variety of culprit objects such as safety pins, parts of toys, plastic elements. In the elderly, oral hardware such as dentures account for the majority of ingested items.

The gastroesophageal junction (GEJ) is the third region of narrowing and is most often perforated iatrogenically during dilations of the distal esophagus for achalasia or distal esophageal strictures. Perforation also results from biopsies in this area during evaluations for metaplasia. The GEJ is the most severely injured area of the esophagus in patients with accidental or intentional ingestion of chemical substances. The relaxation of the LES in response to injury along with intense pylorospasm results in continued reflux of caustic substances into the distal esophagus. This prolongs contact with the mucosa resulting in more severe injuries. Alkaline substances tend to create a more severe injury to the esophagus due to the liquefactive necrosis and the slow transit time, while acids tend to move more quickly through the esophagus and create a coagulative necrosis limiting the depth of injury.

Spontaneous perforation of the esophagus (Boerhaave’s) is most commonly discovered in the distal left posterior lateral aspect about 2 to 3 cm from the GEJ. This area has a less developed muscular layer to accommodate the exit of neurovascular structures and tapering of the muscle as to spread out onto the stomach wall, allowing the increased pressure during retching to result in rupture into the left chest. The cervical esophagus is much more vulnerable to external trauma than
the thoracic esophagus and up to 6% of penetrating injuries to the neck may have a concomitant esophageal perforation, whereas only 0.7% of penetrating thoracic injuries result in an injury to the esophagus. Blunt traumatic injury to the esophagus is extremely rare and is almost always located in the cervical esophagus (Table 147.1).








Table 147.1 Causes of Esophageal Perforation






Spontaneous (Boerhaave’s syndrome)
Iatrogenic
   Endoscopy (esp. with sclerotherapy or biopsy)
   Dilation with bougie or balloon
   Naso/orogastric tubes
   Endotracheal intubation
   Operative injury
Trauma
Caustic ingestion
Infections (tuberculosis, herpes simplex, CMV)
Malignancy
Zollinger–Ellison syndrome
Note: The percentages of each etiologies will vary depending on the location of the perforation and time period studied.
CMV, cytomegalovirus.


Presentation

Delay in diagnosing an injury to the esophagus is the most important determinant of mortality in this disease and thus a high index of suspicion should be maintained whenever injury to the esophagus is a possibility in a differential diagnosis. Perforation of the esophagus leads to contamination of the surrounding tissues in the neck, mediastinum, or abdomen and localized sepsis due to the degree of aerobic and anaerobic bacterial contamination. Chief complaints are therefore related to the effects of local tissue inflammation and the systemic inflammatory response. The most common presenting symptom in patients with esophageal perforation is pain followed by other common signs including fever, dyspnea, and subcutaneous emphysema, which may extend into the head and neck. Auscultation of the heart tones may reveal a crunching sound that is related to air in the mediastinum and is a classic sign of esophageal perforation. Pain resulting from esophageal perforation is dependent on the location. A cervical perforation tends to cause less pain and more vague symptoms of neck stiffness, headache, and backache. Symptoms with more distal perforation in the thoracic esophagus tend to be substernal and can lateralize to the side of perforation with proximal esophageal perforations tending to be on the right side and more distal perforations on the left side. This must be differentiated from acute coronary syndromes and should be considered in patients with severe chest pain after an acute myocardial infarction has been eliminated as the etiology.

Presenting signs of perforation may be subtle and nonspecific in the early phase with tachycardia being the most well recognized, and persistent tachycardia in a patient who has undergone an endoscopic evaluation or a surgical procedure involving the esophagus should warrant an evaluation for rupture. As the course progresses, these patients rapidly develop systemic sepsis with hypotension and tachycardia, tachypnea and worsening respiratory distress, renal failure, and mental status alterations. Failure to recognize septic shock and intervene early in this patient population may lead to death within 12 to 24 hours.


Diagnostic Evaluation

A chest radiograph is often one of the first tests obtained in patients with pain in the chest or neck. The presence of a pleural effusion, pneumothorax, or pneumomediastinum, in the setting of a suspicious history, is highly suggestive of an esophageal perforation. A contrast esophagram, however, is the gold standard for diagnosis of perforation. It has a high sensitivity and specificity and is relatively easy to obtain in any facility. Following an initial evaluation with water-soluble contrast, a barium contrast study should be done to rule out a leak. The false negative rate for esophageal perforation utilizing water-soluble contrast is 20% to 25%, even when digital subtraction imaging techniques are used [3,4]. Therefore, a negative study with water-soluble contrast does not complete the evaluation [5]. Concern over the inflammatory reaction associated with barium extravasation in the setting of bacterial contamination is warranted if an intra-abdominal perforation is suspected and the patient is presenting with peritonitis [6]. Such a response has not been demonstrated in the mediastinum and barium should be used to increase the sensitivity of the imaging [7]. Patients who cannot perform a swallowing test or are in extremis are most often imaged with computed tomography with oral contrast administered by nasogastric tube, which must be positioned in the proximal esophagus to provide diagnostic value. The key finding on a computed tomography (CT) scan for diagnosing a perforation is an extraluminal collection of gas or subcutaneous emphysema. Periesophageal fluid collections with air-fluid interfaces, esophageal wall thickening effacement of fat planes, extravasation of oral contrast and pleural effusions are other radiographic findings consistent with a perforation. Computed tomography is also useful in the evaluation for abscess or empyema formation with a long-standing leak [8,9,10,11] (Fig. 147.2).

The role of esophagoscopy in the diagnosis of esophageal perforation has been established in the setting of traumatic injuries with a high sensitivity for detecting injury [12,13,14]. In non-traumatic settings, the sensitivity has not been established and the use of endoscopy remains as an adjunct to imaging modalities. This may be related to the difficulty in locating sites of perforation in the esophageal mucosa when there are no attendant signs of trauma [15].


Treatment

There is a paucity of reliable data regarding the treatment of esophageal perforation. This is partly a result of the fact that patients present with a wide variety of symptoms, differing severity of injury and are treated by several different specialties. Several principles in the management of esophageal perforation are paramount: control of ongoing soilage by closure of the leak, management of sepsis with adequate drainage and support of the patient with fluids, nutrition, and appropriate antibiotics.

After goal-directed resuscitation and initiation of broad-spectrum antibiotic therapy, the treatment of choice for most patients with perforations of the esophagus remains surgical. For early perforations less than 24 hours in hemodynamically stable patients, consideration may be given to direct primary repair of the injury. This is generally possible in cases where there is a small injury with little soilage or devitalized tissue in a surgically accessible location and early detection has been achieved. Access to the cervical esophagus is generally obtained through an anterior neck incision along the anterior border of the left sternocleidomastoid muscle. The carotid sheath and its contents are retracted laterally and the thyroid and trachea retracted medially to expose the esophagus. In the mediastinum,
a right posterolateral thoracotomy is used to access lesions in the middle third of the esophagus and a left posterolateral thoracotomy provides exposure for the distal third of the thoracic esophagus. Upper midline laparotomy or left thoracotomy may be used to access the gastroesophageal junction. If amenable to repair, the esophagus is usually closed with a single layer of interrupted full thickness sutures and the anastomosis is reinforced with a well-vascularized local tissue flap from the latissimus dorsi muscle, pericardium, or omentum.






Figure 147.2. Algorithm for the diagnosis and management of a perforation of the esophagus. Early diagnosis followed by resuscitation and surgical consultation are the keys to decreasing the mortality from this highly lethal condition.

In cases where the diagnosis has been delayed for more than 24 hours, there is extensive tissue injury, or intense local sepsis, primary repair is ill-advised. In this situation, it is prudent to perform a resection of the esophagus or proximal diversion with a cervical esophagostomy and exclusion of the injured esophagus with creation of enteral feeding access. After the resolution of sepsis and once the patient is nutritionally repleted, reestablishment of intestinal continuity can be achieved with a gastric pull-up or intestinal interposition techniques. If there is a coexisting underlying esophageal pathology such as megaesophagus, achalasia, esophageal stricture, or carcinoma, esophagectomy with or without reconstruction is the operation of choice. In patients who cannot tolerate a definitive repair, surgical management should be limited to placement of an esophageal T-tube for drainage and creation of a controlled esophageal fistula.

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Sep 5, 2016 | Posted by in CRITICAL CARE | Comments Off on Esophageal Perforation and Acute Mediastinitis

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