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Bronchoscopic Perspective

1974; Elsevier BV; Volume: 65; Issue: 6 Linguagem: Inglês

10.1378/chest.65.6.606

1931-3543

Daniel M. Kovnat, John T. Schaaf, G S Rath, Gordon L. Snider,

Tracheal and airway disorders

The editorial entitled, “The Flexible Fiberscope in Bronchoscopic Perspective” by Tucker, Olsen, Andrews and Pool, published in Chest 64:149, 1973 provides a constricted and seriously limited point of view of flexible fiberoptic bronchoscopy. Although we concur with the editorialists in deploring the use of the instrument by untrained individuals, the ease with which the bronchoscope can be passed into the bronchial tree is one of its great strengths. We cannot agree, however, that individuals must be trained in rigid tube bronchoscopy and esophagoscopy in order to become competent flexible tube bronchoscopists. Rigid tube bronchoscopy is clearly needed for foreign body removal and operative manipulations. However, foreign bodies are rare problems even on a busy adult pulmonary disease service and if a physician skilled in foreign body removal is not locally available, the diagnosis can be readily made and the patient referred to an appropriate center. The authors list many of the reasons for the superiority of flexible bronchoscopy over rigid bronchoscopy in diagnostic work. However, they cite no evidence to support their position that flexible bronchoscopy should be considered an adjunct to conventional endoscopy. Their often repeated statement that the flexible bronchoscope may produce airway obstruction is also not documented. Upper airway obstruction is the single, most important respiratory complication of general anesthesia.1Severinghaus JW Larson Jr., CP Respiration in anesthesia.in: Fenn WO Rahn H. Handbook of Physiology, Section 3: Respiration. Williams and Wilkins, Baltimore1965Google Scholar Safar et al2Safar P Escarraga LA Chang F Upper airway obstruction in the unconscious patient.J Appl Physiol. 1959; 14: 760-764Crossref PubMed Scopus (224) Google Scholar have shown that in the supine position, without extension of the neck, the tongue pushes the base of the epiglottis against the false cords resulting in obstruction of the hypopharynx. This has been radiographically demonstrated in conscious individuals in the prone position.3Asmussen E Hahn-Petersen A Rosendal T Air passage through the hypopharynx in unconscious patients in the prone position.Acta Anaesth Scand. 1958; 3: 123-127Crossref Scopus (4) Google Scholar The possibility of this obstruction is obviated by the performance of bronchoscopy in the sitting position. The dimensions of the adult larynx and trachea are ample for passage of the 5 mm flexible bronchoscope as well.4Gray H Anatomy of the Human Body. Lea and Febiger, Philadelphia1959Google Scholar It is well known that before significant symptoms occur, the trachea must be narrowed to less than 1 cm. This is not accomplished with the 5 mm almost completely closed tube. Furthermore, experience with fiberoptic bronchoscopy through endotracheal tubes has shown that adequate ventilation can be maintained with an airway of internal diameter down to 8.5 mm—a difference in diameter between bronchoscope and airway of only 3.5 mm.5Renz LE Smiddy JF Rauscher CR et al.JAMA. 1972; 219: 619Crossref PubMed Scopus (17) Google Scholar In our experience, airway obstruction has not been clinically significant in transnasal passage of the 5 mm flexible fiberoptic bronchoscope in the sitting position. We also remain unconvinced on the basis of extensive experience with flexible bronchoscopy of the need for special, expensive endoscopy facilities and assistants. Complications of the procedure have been of extremely low incidence with a recently reported morbidity of less than 1 percent and a mortality of less than 0.01 percent.6Credle Jr, WF Smiddy JF Elliott RC Complications of fiberoptic bronchoscopy.Am Rev Resp Dis. 1973; 107: 1091Google Scholar There is no doubt that certain seriously ill patients should be monitored during and following bronchoscopy not only by continuous electrocardiogram and clinical observation, but by serial blood gases to be certain that oxygen enrichment of inspired air is effectively controlling hypoxemia. All patients who are to have bronchoscopy should have a physical examination and electrocardiogram; a forced expiratory spirogram should be done and arterial blood gases measured if indicated. These screening procedures will identify the relatively few patients who require monitoring; most other patients can be bronchoscoped in a relatively inexpensively staffed and equipped facility. The same screening process should be followed for examination of outpatients, thus further reducing the cost of bronchoscopy without loss of efficacy or safety. Some patients who are not readily moved (ie, paraplegics or those in hip spica casts) are more safely and readily bronchoscoped in their own rooms; portable monitoring equipment is brought to the patient if necessary. Tucker et al fail to mention the use of flexible bronchoscopy in the intubated patient who is being mechanically ventilated. Flexible endoscopy is easily performed in this circumstance using any of a variety of simple homemade adapters with minimal alteration of arterial blood gases.7Pierson DJ, Iseman MD, Sutton FD, et al: Therapeutic bronchofiberoscopy during assisted ventilation. Abstract of presentation at La Jolla Shores Medical Conference, Scripps Memorial Hospital, September, 1973Google Scholar Rigid endoscopy of the intubated, mechanically ventilated patient is difficult and requires specialized ventilating bronchoscopes if alveolar ventilation is to be kept constant during the procedure. The use of apneic oxygenation or intermittent ventilation has been shown to result in wide variations of arterial blood gases.8Jenkins AV Sammons HG Carbon dioxide elimination during bronchoscopy.Br J Anaesth. 1969; 40: 533-538Abstract Full Text PDF Scopus (2) Google Scholar These methods should never be used in the mechanically ventilated patient. It is true that rigid bronchoscopy can often be accomplished much more quickly than flexible bronchoscopy, but this is because the flexible bronchoscope permits inspection of a much greater extent of the tracheobronchial tree than the rigid instrument. If only the extent of the tracheobronchial tree accessible to the rigid instrument were examined, the time required for the procedure would certainly be less with the fiberoptic bronchoscope. Insistence on performing flexible bronchoscopy concomitant with rigid tube endoscopy can only increase the total duration of the procedure. The tissue biopsy obtained through the flexible instrument is small and crush artifact is frequent, a difficulty not faced by the rigid tube bronchoscopist who has larger forceps with a wide range of designs readily available. However, the greater accessibility of lesions to direct inspection and bronchial brushing, and the ease of performing indirect brushing of a peripheral lesion under fluoroscopic control with the flexible instrument more than makes up for any deficiency in the biopsy obtained. Hopefully, instrument manufacturers will improve the flexible biopsy forceps with resultant improvement in histologic quality of the tissue obtained. Flexible fiberoptic bronchoscopy offers greatly increased visualization of the bronchial tree, greater diagnostic accuracy, greater patient comfort, increased range of applicability of the procedure with decreased patient risk and decreased expense. The undersigned, therefore, believe that flexible fiberoptic bronchoscopy should become the primary procedure for diagnostic purposes.