Unsuspected Pulmonary Collapse During Neuroradiologic Procedures

During general anesthesia an endotracheal tube is considered a valuable safety device to maintain airway patency. This presupposes that the tube is carefully placed in the trachea and little motion of the patient or tube takes place during the ensuing procedure. The purpose of this paper is to report on pulmonary complications, not suspected clinically, resulting from movement of the endotracheal tube during neuroradiologic procedures. The motion of the head and neck from extension to flexion, and of the patient from erect to recumbent position, may cause a significant downward motion of the endotracheal tube, obstructing a major bronchus. Material and Methods Twenty consecutive patients undergoing special neuroradiologic procedures under general anesthesia were examined radiographically. By means of two chest roentgenograms, the position of the tip of an endotracheal tube was determined with the patient's chin in acute forward flexion and in extension. When feasible, these roentgenograms were obtained with the patient in both seated and recumbent positions. The focal spot-film distance for the recumbent films was fairly constant at 55–60 inches. Measurements obtained from the films (see below) were not corrected for magnification. The neuroradiological examinations consisted of eleven pneumoencephalograms, eight carotid angiograms, and one myelogram. In all cases, intubation was performed by a staff anesthesiologist or a resident anesthesiologist under direct staff supervision. The age distribution of the 20 patients is given in Table I. Sixteen of the 20 were under the age of ten years. An armored endotracheal tube was used most frequently. This type of tube has a coil of wire incorporated in the wall to prevent kinking, and a beveled rubber tip extends from the distal end of the tube for 3 to 8.5 mm, depending on the diameter of the tube. Since this beveled portion is not densely opaque, measurements of the tube on the flexion-extension chest films had to be taken from the terminal coil of wire in the tube. Results In this series of 20 patients the tube tip movement in recumbent flexion and extension averaged 1.2 cm, with a range of 0.3–2.6 cm (Table I). Pulmonary complications were encountered in 4 of the 20, due to obstruction of a bronchus by the endotracheal tube. Three had diffuse atelectasis in both lungs, and one had right upper lobe collapse. All 4 patients were less than two years old. In no instance did the anesthetic course reveal any clue to this bronchial obstruction, such as changes in standard measurements of vital signs. The first case (Fig. 1) was of a 7-month-old child with obstruction of the right upper lobe bronchus by the tube on flexion only. The tube was repositioned, and a later film (Fig. 1, C) shows partial re-expansion. This case illustrates that downward motion of the endotracheal tube on flexion may cause obstruction in this position only. The tube motion was 1.5 cm.