Anesth Analg 2003;97:909-910
© 2003 International Anesthesia Research Society
GENERAL ARTICLES
Failure to Detect an Unusual Obstruction in a Reinforced Endotracheal Tube with Fiberoptic Examination
Matthias Paul, MD DEAA,
Michael Dueck, MD DEAA,
Sandra Kampe, MD, and
Frank Petzke, MD
Department of Anesthesia and Intensive Care Medicine, University of Cologne, Cologne, Germany
Address correspondence and reprint requests to Matthias Paul, MD, DEAA, Department of Anesthesia and Intensive Care Medicine, University of Cologne, Joseph-Stelzmann-Str. 9, D-50924 Cologne, Germany. Address e-mail to m.paul{at}uni-koeln.de
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Abstract
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IMPLICATIONS: This report describes an unusual obstruction of a reinforced endotracheal tube caused by a partial detachment of the inner coating from the embedded spiral. Fiberoptic inspection is a recommended procedure for a suspected obstruction, but failed to identify this valve-like detachment. This detachment was likely caused by re-autoclavation of the tube, which was a specified single-use product.
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Introduction
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Endotracheal intubation is performed to establish a secure airway. However, it is not without risks, and obstruction of an endotracheal tube (ETT) is a potentially life-threatening event (1). We report an unusual case of ETT obstruction caused by the detachment of the inner coating from the spiral of a reinforced tube.
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Case Report
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A 49-yr-old woman (161 cm, 85 kg) with a pituitary adenoma was scheduled for transphenoidal hypophysectomy. She was a nonsmoker with no history of bronchospastic disease. Because of a known difficult airway, we scheduled her for an awake oral intubation with fiberoptic guidance.
After placement of routine monitoring, the patient was premedicated with IV midazolam (2 mg) and fentanyl (100 µg). Topical anesthesia was achieved by nebulization of lidocaine 4%. A 7.0-mm reinforced tube (Ruesch AG, Kernen, Germany) was easily mounted on the fiberoptic scope, which was advanced into the trachea without problems. Upon advancement of the ETT, the patient coughed heavily and general anesthesia was induced with sodium thiopental (350 mg) and fentanyl (100 µg). After connection to the anesthetic circuit and manual ventilation with 100% O2, no end-tidal CO2 was detectable and peak inspiratory pressure increased quickly to >40 cm H2O with a visible increase in thoracic volume. On auscultation, weak bilateral inspiratory breath sounds could be heard, but no expiratory sounds were noted.
Disconnection and inspection of the anesthetic circuit and the CO2 analyzer revealed no abnormality. For fiberoptic inspection of the ETT and trachea, the ETT was manually fixed in position at the mouth and slightly stretched to facilitate reinsertion and advancement of the fiberscope. The fiberscope was easily passed through the ETT and no obstruction or kinking of the correctly positioned tube was noted. Direct laryngoscopy revealed no external obstruction or twisting of the visible oropharyngeal section of the ETT. Ventilation of the patient’s lungs was then attempted with a self-inflating bag but this did not reduce the degree of chest expansion. Bilateral manual compression of the thorax generated a wheezing sound which seemed to confirm the suspected diagnosis of severe bronchospasm with overinflated lungs. Treatment for bronchospasm included albuterol spray, sevoflurane (2.5 vol%), IV ketamine, fentanyl, and theophylline as well as subcutaneous terbutaline. Arterial blood gas analysis revealed an increased CO2 level and normal oxygenation (pH 7.36, PCO2 61 mm Hg, PaO2 468 mm Hg, SaO2 100%). Fiberoptic examination was repeated twice, but no abnormality was detected. However, during deflation and reinflation of the cuff to check for a cuff hernia, overexpansion of the thorax was partially relieved. This observation caused us to change the ETT despite her difficult airway and the potential inability to mask-ventilate the patient. Direct laryngoscopy was achieved with a McCoy laryngoscope. Upon removal of the ETT, the thorax deflated completely. After placement of a new reinforced tube (7.0 mm, Ruesch AG), ventilation was easy with peak airway pressure <25 cm H2O and clear inspiratory and expiratory breathing sounds. The patient was connected to the ventilator and the remainder of the anesthetic proceeded uneventfully.
On inspection of the removed ETT, a barely visible internal meniscus in the tube was detected only after placing it in front of a light source (Fig. 1). Visual inspection of the inside of the ETT revealed a complete internal obstruction midway within the tube. We identified the obstruction as a partial, flap-like detachment of the thin inner polyvinyl chloride (PVC) lining covering the metal spiral of the reinforced tube, which acted like a valve (Fig. 2). When the tube was stretched, the detachment realigned itself, allowing an unobstructed view through the lumen of the tube.
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Figure 1. Reinforced polyvinyl chloride (PVC) endotracheal tube (7.0 mm) with detachment of the inner PVC lining. Arrows point toward the barely visible internal meniscus created by the detachment.
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Figure 2. Internal view of the reinforced endotracheal tube, cut lengthwise. The flap-like detachment of the inner lining of the spiral is clearly visible. Cutting open the tube may have slightly damaged the detachment.
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Discussion
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Obstruction of an ETT by mucus, blood, or a kink is not uncommon, whereas obstruction by a foreign body is a rare event (1). Various foreign bodies (2–5) and "biting down" on the spiral of a reinforced ETT (6) have been reported to cause obstruction. The recommended maneuvers for a suspected obstruction of an ETT include passing a suction catheter through the tube and performing a fiberoptic examination (7). Fiberoptic inspection would have identified all the above-mentioned causes for an obstructed tube, but failed to detect the detachment of the inner lining of the reinforced tube in our case. Fixation with slight stretching of a flexible reinforced ETT is necessary to facilitate insertion and advancement of the fiberscope. Unfortunately, in our case, this stretching led to a realignment of the detached material, making the detection of this valve-like obstruction impossible. Our decision to change the ETT was delayed because repeated fiberoptic examinations had revealed no abnormalities, because the patient had a difficult airway, and because we suspected severe bronchospasm which might have made mask ventilation impossible.
We assumed that the damage of the tube might have been caused by faulty fabrication and informed the manufacturer. It was explained that during the production process of spiral tubes, a rod is dipped into liquid PVC, creating a thin PVC layer around the rod. The spiral is then mounted onto the rod and the dipping procedure is repeated several times, creating the outer coating of the spiral. The manufacturer suggested that the detachment of the inner coating had likely been caused by exposure to heat, e.g., because of autoclavation, which is not recommended for this single-use product. Further investigation within our department revealed that the problematic tube had indeed been re-autoclaved after it had been unwrapped in the previous week but was not used because of the cancellation of a case. Our case supports a previous statement by other authors that cutting costs by re-using ETTs, which are not meant to be re-autoclaved, is likely to be at the expense of patient safety and therefore cannot by justified (8).
We conclude that the successful passage of a suction catheter through an ETT, and even apparently normal fiberoptic examination, do not guarantee complete patency of the ETT.
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Acknowledgments
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Support was provided solely from institutional and/or departmental sources.
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References
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- Wright PJ, Mundy JV, Mansfield CJ. Obstruction of armoured tracheal tubes: case report and discussion. Can J Anaesth 1988; 35: 195–7.[Medline]
Accepted for publication April 24, 2003.
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Abstract
Introduction
