To the Editor: I should like to call attention to an error inCase 46-1992 (Nov. 19 issue)1. The patient, a middle-aged womanwith severe tracheal distortion, was described as having undergoneplacement of "a 6-French pediatric cuffed endotracheal tube"before coronary-artery bypass surgery. This is extremely unlikely,since a 6-French endotracheal tube has an external diameterof less than 2 mm and is not commercially available. Its smallinternal diameter (less than 1.5 mm) would have greatly increasedresistance to airflow; perioperative ventilation and oxygenationwould have been almost impossible2. It is more likely that a6.0 endotracheal tube (internal diameter, 6.0 mm) was placed.The patient's inability to accommodate a larger endotrachealtube (internal diameter, 7.0 mm) was unusual and suggested thatthe anatomy of her airway was abnormal.
Paul Lennon, M.D. National Naval Medical Center Bethesda, MD20889
References
Case Records of the Massachusetts General Hospital (Case 46-1992). N Engl J Med 1992;327:1512-1518. [Medline]
Dallen LT, Wine R, Benumof JL. Spontaneous ventilation via transtracheal large-bore intravenous catheters is possible. Anesthesiology 1991;75:531-533. [Medline]
To the Editor: The anatomical diagnosis in Case 46-1992 -- "Tracheopathiaosteoplastica. (Saber-sheath trachea.)" -- is misleading iftaken at face value. The unfortunate parenthetical juxtapositionwrongly implies an association, equivalence, or identity betweensaber-sheath trachea and tracheopathia osteoplastica, when infact none exists. As noted by the discusser, a saber-sheathtrachea is a deformity confined to the intrathoracic portionof the trachea1. In the patient described in Case 46 both thecervical and thoracic portions of the trachea were deformedby tracheopathia osteoplastica. The saber-sheath deformity,in contrast, is confined to the intrathoracic trachea and isclosely associated with clinical signs of chronic airways disease,especially chronic bronchitis2. It is thought to develop fromcoughing-induced chronic degeneration and softening of trachealcartilage, with subsequent abnormal reformation due to intrathoracicforces. There is no "saber-sheath trachea" in this case, butan unrelated deformity of the cervical and intrathoracic tracheadue to tracheopathia osteoplastica.
Reginald Greene, M.D. Massachusetts General Hospital Boston,MA 02114
References
Greene R, Lechner GL. "Saber-sheath" trachea: a clinical and functional study of marked coronal narrowing of the intrathoracic trachea. Radiology 1975;115:265-268. [Abstract]
Greene R. "Saber-sheath" trachea: relation to chronic obstructive pulmonary disease. AJR Am J Roentgenol 1978;130:441-445. [Abstract]
The authors reply:
To the Editor: Dr. Lennon is probably correct in his observation.The patient had undergone coronary bypass surgery at anotherinstitution. The size of the cuffed endotracheal tube was transcribedfrom the referred operative report, without correction.
The diagnoses of tracheopathia osteoplastica and saber-sheathtrachea were meant to be separate. There was no intention toequate the two. The general use of parentheses in the anatomicaldiagnosis is to indicate that such a diagnosis may be presentbut that there is no anatomical proof of it. The diagnosis ofsaber-sheath trachea was based on the endoscopic appearanceof a saber-sheath-like deformity observed at endoscopy, andwas placed in parentheses because the deformity was not presentin the resected specimen. We agree with Dr. Greene that "saber-sheath-likedeformity" would have been more correct than "saber-sheath trachea."
Eugene J. Mark, M.D. Hermes C. Grillo, M.D. Massachusetts GeneralHospital Boston, MA 02114
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