CHAPTER 5 Endoscopic Diagnosis of Thoracic Disease
Endoscopy, especially fiberoptic endoscopy, has revolutionized nearly all theaters of medicine in terms of diagnosis and therapeutic intervention.1 This is particularly true for thoracic surgery, where bronchoscopy and esophagoscopy are essential modalities in the diagnosis, approach, and treatment of tracheal, bronchial, and alimentary tract pathology. As the technology of optics, endoscope instrumentation, and appurtenances such as endoscopic ultrasound and yttrium-aluminum-garnet (YAG) laser have evolved, so have the indications and capabilities of the skilled endoscopist. Although many clinicians may perform endoscopy, thoracic surgeons in particular should be adept and pioneering with these procedures, because new endoscopic technology will continue to enable all aspects of minimally invasive thoracic surgery.
In 1868, Kussmaul intubated a sword swallower’s stomach via the esophagus with a 13-mm hollow metal tube. This maneuver proved that the oral cavity, esophagus, and stomach could be simultaneously intubated with one rigid instrument. Mikulicz added one crucial aspect to the tube—a distal light to illuminate the esophagus and stomach—and he was able to visualize gastric motility and view probable malignancies. The fiberoptic endoscope was introduced in 1958. This instrument allowed more patient comfort as well as greater therapeutic possibilities in the distal stomach and proximal small intestine. Although the scope itself has not changed greatly, the adjunctive instruments have dramatically changed the way many disease states can be treated.2
For the thoracic surgeon, dysphasia and odynophagia are two of the most common indications for esophageal endoscopy (Box 5-1). Others include reflux, an abnormal esophagogram, trauma, screening, or staging of gastrointestinal (GI) or adjacent masses including tracheoesophageal fistulas. Upper GI bleeding is another very common indication for endoscopy, which has become the first line in management of this clinical scenario.
Box 5–1 Indications for Upper Endoscopy∗
According to the American Society for Gastrointestinal Endoscopy. Appropriate use of gastrointestinal endoscopy. Gastrointest Endosc 2000; 52:831-37.
Dysphagia can arise from a number of pathologic processes. Many causes can be distinguished with a careful history that records the duration and persistence of symptoms and accompanying constitutional symptoms. Endoscopy allows the surgeon to assess the possibility of malignant as opposed to benign causes of dysphagia, thereby guiding therapy.
Reflux is another indication for upper endoscopy. The thoracic surgeon searches for any long-term sequelae associated with chronic gastroesophageal reflux disease (GERD), such as Barrett’s esophagus. Esophagoscopy is crucial in the surveillance of known Barrett’s esophagus because of the link with the development of adenocarcinoma, although the interval at which these patients should be followed is still unclear.
Upper GI bleeding is another indication for endoscopy, and the procedure is often used therapeutically, as with bleeding esophageal varices, a difficult problem, that can be palliated endoscopically with banding or sclerotherapy.
The most common reason for a thoracic surgeon to perform upper endoscopy is to visualize and biopsy esophageal and proximal stomach masses. Biopsy has a sensitivity of 66% to 96% in esophageal cancers.3,4 Seven to 10 biopsies are usually taken throughout the area of the lesion, or randomly in the setting of Barrett’s esophagitis. For lesions with a tight stricture, the surgeon can use a small-diameter scope, and brushings have been shown to increase the yield of tissue in such cases.4,5 The role of endoscopic ultrasound in the diagnosis and staging of esophageal disease will be discussed later.
Upper endoscopy can also play a role in the assessment of other mediastinal masses and malignancies that cause esophageal obstructive symptoms. Endoscopy may reveal whether the lesion is causing mass effect or actual erosion through the wall of the esophagus, possibly resulting in a fistula.
Upper endoscopy is also important for investigating trauma—blunt, penetrating, or caustic—and for foreign body retrieval. The thoracic surgeon is frequently asked to document and manage iatrogenic trauma to the esophagus via instrumentation. Although the esophagogram is the mainstay for the diagnosis of perforation, the usefulness of endoscopy for the diagnosis and documentation of the extent of injury should not be underestimated. When using endoscopy to remove foreign bodies lodged in the esophagus, the surgeon should be alert to the potential for intraesophageal lesions, which may be responsible for the failure of material to pass through.
Corrosive ingestion is another indication for early (within 36 hours) endoscopic inspection,6 which can help identify transmural involvement and subsequent development of strictures.
Most endoscopies can be performed on an outpatient basis with conscious sedation. Patients should receive nothing by mouth (NPO) after midnight for a morning examination, and those with obstructive symptoms should be placed on a clear liquid diet for 24 to 48 hours before the examination. When the patient arrives, a peripheral intravenous line and electrocardiogram (ECG) leads should be placed. Because the sedatives can cause respiratory depression, ECG and pulse oximetry readings are taken constantly, and blood pressure measurements are obtained frequently during the procedure. Once the monitors are in place, sedation is given to ensure that the patient is comfortable and cooperative. Local anesthesia minimizes the degree of conscious sedation required.
The most common position for examination of the outpatient is the left lateral decubitus, with the head flexed. A bite block is placed into the mouth to protect the endoscope from the teeth, and the endoscope is introduced under direct vision. The epiglottis and larynx should be seen and advanced over until the piriform sinuses become apparent. If the vocal cords are visualized, any abnormalities should be documented. Gentle pressure is applied against the upper esophageal sphincter at the cricopharyngeus and the patient is instructed to swallow, which usually results in successful and atraumatic esophageal intubation.
The four normal endoluminal landmarks in the esophagus are as follows: (1) the upper esophageal sphincter at the cricopharyngeus, 15 to 18 cm from the incisors; (2) the aortic arch, usually evident as an indentation on the left anterolateral wall; (3) the left atrium, seen in the distal esophagus as wavelike pulsations of the anterior wall of the esophagus; and (4) the lower esophageal sphincter, which in reality is just a physiologic sphincter, and which can be demonstrated by asking the patient to perform a Valsalva maneuver and noting the pinching off of the lumen. The esophagus is generally easy to assess, and very little air insufflation is required to view its entire course.
Once the gastroesophageal junction has been passed, it is easy to advance into the stomach. The stomach should be insufflated with enough air to flatten out the rugae and allow visualization of the entire mucosal surface. The pylorus is visualized, and the scope can be advanced beyond the sphincter when it is relaxed. The duodenum should be inspected to the third portion. Once this has been performed satisfactorily, the scope should be removed slowly to see any potentially missed pathology. In the stomach, retroflexion of the scope allows the visualization of the body and cardia of the stomach. Insufflated air should be suctioned before leaving the confines of the stomach. During the withdrawal, the scope should be pulled back slowly to more carefully assess the esophagus. Then the endoscope is removed and monitoring of the patient continues.
Rigid esophagoscopy is a rarely used modality, usually reserved for three instances: trauma, removal of impacted food, and removal of foreign bodies. The scope is held in the examiner’s right hand while the left hand keeps the mouth open with the left thumb protecting the upper dentition. During the insertion of the scope, the head is initially held forward, in the “sniffing position” used for tracheal intubation; once the cricopharyngeus is passed, the head is extended to eliminate the angle of the mouth and the pharynx. The scope can then be carefully advanced throughout the length of the esophagus and proximal stomach; manipulating the head and cervical spine at the areas of narrowing allows less traumatic passage.
Endoscopic ultrasound (EUS), for which a small ultrasonic transducer is attached to the end of the endoscope, is a relatively new adjunctive procedure that has expanded the examination of the esophagus and the periesophageal tissues. It is never an initial procedure but is indicated when a previous esophagoscopy has been performed and pathology has been located and evaluated. Indications for esophageal ultrasound range from benign to malignant esophageal disease and include evaluation of periesophageal pathology, usually bronchogenic carcinoma (Box 5-2). The most common indication for EUS is the evaluation of esophageal malignancy. The stage of the lesion, as defined by the depth of invasion and nodal involvement, is the best predictor of surgical resection and therefore possible cure.