경희의학 : 제 32 권제 1 호 증 례 J Kyung Hee Univ Med Cent : Vol. 32, No. 1, 2017 Unexpected Difficult Intubation Caused by Idiopathic Subglottic Stenosis Joo Hyun Jun 1, Mi Hyun Lee 1, Eun Mi Choi 1, Eun Mi Kim 1, Young Ryong Choi 1, Pil Hyun Jeon 1, Seung Hwa Baek 1, Mi Hwa Chung 1, Sung Wook Park 2 1 Department of Anesthesiology and Pain Medicine, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, 2 Department of Anesthesiology and Pain Medicine, School of Medicine, Kyung Hee Medical University, Seoul, Korea INTRODUCTION Subglottic stenosis (SGS) is defined as a partial narrowing of the subglottic region of the trachea. This disorder may present congenitally, or it can be acquired. Among patients with acquired SGS, the majority of cases are iatrogenic and are predominantly attributed to a history of ETT intubation and laryngeal trauma. Other identifiable causes for SGS include systemic conditions such as Wegener s granulomatosis, gastroesophageal reflux disease, and sarcoidosis.(1-4) Although extremely rare, SGS may present without an identifiable cause, and the condition is then referred to as idiopathic SGS.(1,2) We report a case of unexpected difficult intubation after induction of anesthesia caused by idiopathic SGS. CASE REPORT A 44-year-old female patient (49.6 kg, 147.2 cm) Corresponding author: Mi Hwa Chung, Department of Anesthesiology and Pain Medicine, Kangnam Sacred Heart Hospital, 1 Singil-ro, Yeongdeungpo-gu, Seoul 07441, Korea Tel: +82-2-829-5230, Fax: +82-2-845-1571 E-mail: mhchung20@hallym.or.kr was scheduled to undergo emergency laparoscopic operation for acute appendicitis. Her medical history included chronic asthma (2 years ago) that was not treated with medication or inhaler. She complained of occasional mild dyspnea with exercise. She had no previous surgeries. There was no active lung lesion on chest X-ray. Both lungs sounds were clear. Her vital sign was stable without fever and preoperative lab was nonspecific except elevated WBC count (17.46x 10^3/ul) probably due to acute appendicitis. In the operating room, the patient was monitored via electrocardiograph electrodes, pulse oximetry and noninvasive blood pressure. After 3 minutes of pre-oxygenation, general anesthesia was induced with propofol 80 mg and remifentanil 0.5-1.0 μg/kg/min. Rocuronium 40 mg was used to produce muscle relaxation. Ventilation was easily performed through a facial mask and laryngoscopy was performed with a Macintosh size 3 blade, which revealed a grade I laryngeal view (Cormack and Lehane); the glottis opening was narrower than normal. Intubation was attempted with a 6.5-mm internal diameter (ID) endotracheal tube (ETT), but the ETT could not be advanced beyond the vocal cords because of resistance. Intubation was then reattempted - 26 -
Joo Hyun Jun, et al:airway Management of Subglottic Stenosis A B Fig. 1. Fiberoptic view during (A) rigid bronchoscopy and (B) otolaryngologic exam; image shows focal subglottic stenosis. Fig. 2. Postoperative transverse view of computerized tomographic scan shows intraluminal trachea narrowing; image shows Vertical diameter : 6 mm, Horizontal diameter : 4 mm at the narrowest point with a 6.0-mm ID ETT, but it could not be negotiated through the subglottic region. After each ETT intubation attempt, mask ventilation remained easy without any decrease in oxygen saturation. Further attempts at intubation were eventually abandoned and a size 3 laryngeal mask airway (LMA) (LarySeal TM Clear, Flexicare Medical Ltd, Mid Glamorgan, UK) was inserted. The patient s lungs were ventilated with a tidal volume of 300 ml at a rate of 10 breaths per minute. Because the glottis opening was narrow, the patient s trachea was wanted to identify with fiberopitc bronchosocpy. It was now possible to ventilate the lungs, but only with high peak airway pressures (34-35 mmhg). Anticipating inadequate ventilation during surgery, the process could not be continued. We decided to awaken the patient and delay the appendectomy until after further airway evaluation. Dexamethasone 10 mg was injected intravenously to prevent airway edema. After reversing neuromuscular blockade with 200 mg sugammadex (Bridion, MSD, Kenilworth, NJ, USA), the LMA was removed and normal emergence from anesthesia occurred. Because of unexpected difficult intubation, an otolaryngologist and pulmonologist were consulted. Fiberoptic bronchoscopy revealed SGS obstructing 75% of the tracheal lumen under the vocal cords (Fig. 1). Computerized tomography (CT) (SOMATOM Definition Flash, SIEMENS, Henkestrasse 127 Germany) scan of the neck showed that severe subglottic stenosis with minimal cross-sectional diameters of 4 5 mm at - 27 -
경희의학제 32 권제 1 호 2017 Fig. 3. A 3D computed tomography reconstruction shows a localized area of severe tracheal narrowing (arrow). the narrowest point. Stenosis extended over a distance of 17-20 mm. Beyond the stenosis, the trachea and central airways were normal (Figs. 2 and 3). As ETT intubation seemed impossible, an open appendectomy under spinal anesthesia was planned. However, her inflammation and abdominal pain subsided with time, so an appendectomy was not performed. To address SGS, the patient was offered a tracheostomy. Because she did not want tracheostomy, the patient declined surgical intervention. Her symptoms due to subglottic stenosis were stable with conservative management, and she continues close outpatient follow-up. DISCUSSION We reported a case of unexpected difficult intubation after induction of anesthesia caused by idiopathic SGS. Idiopathic SGS is a rare, slowly progressive inflammatory condition affecting the subglottis and first 2 tracheal rings.(1,2) Idiopathic SGS is the third most common cause of benign laryngotracheal stenosis, and it accounts for about 10 to 35% of SGS cases. It is usually identified in healthy women in the third to fifth decades of life.(2,3) Although hormones, gastroesophageal reflux disease, respiratory tract infection, cough, and autoimmune disease are potential causative factors, the mechanism and exact etiology remain unclear.(1-4) Because the symptoms of SGS are often subtle, identification of SGS can be very difficult. Clinical signs may not appear until an internal diameter of about 75% narrowing occurs.(5) Initial clinical signs are usually shortness of breath rather than stridor. Many patients are misdiagnosed with asthma before subsequent identification of SGS.(2,3) In this case, the patient s exertional dyspnea was attributed to asthma. Therefore, the medical history of the patients with respiratory symptoms should be investigated in detail. Estimation of the level and degree of stenosis can be determined by fiberoptic bronchoscopy, surgical endoscopy, or imaging studies like CT or MRI scan. Initial therapy may be conservative, including observation. Surgical treatment is comprised of serial incisions and dilations, mucosal rotational flaps, or tracheal resection and reanastomosis.(3,6,7) Several methods are available to secure the airway in patients with SGS. Insertion of a smaller diameter ETT is usually the method of choice for airway management in patients with a potential risk of causing trauma to the tracheal mucosa.(8,9) Gentle management of ETT is needed to avoid serious complications, such as bleeding, edema, or even tracheal perforation.(10) The narrowest diameter of the stenosis in our patient was 4-5 mm, which was equivalent to the outer diameter of a 3.5-mm ID ETT. Because the stenosis diameter was determined from CT images, it could have been even smaller. In our case, insertion of an ETT was practically impossible. Another method is to avoid tracheal intubation by using supraglottic airway devices. Supraglottic airway devices were used with success for airway management of these patients during procedures. - 28 -
Joo Hyun Jun, et al:airway Management of Subglottic Stenosis (11,12) In this case, ventilation by LMA could take place only with high peak airway pressures. This may be because the stenotic region was too narrow compared to prior cases, and 2 intubation attempts may have caused airway edema. Because ventilation was maintained after several airway manipulations, it seemed safer to awaken the patient without further airway injury and plan for a delayed appendectomy after 6.0-mm ID ETT also failed. Although a laryngeal mask airway was inserted, ventilation was inadequate. The appendectomy was cancelled. Because of the unexpectedly difficult intubation, an otolaryngologist was consulted to examine her larynx, and subglottic stenosis (SGS) of unknown origin was suggested. We present a case of unexpected difficult intubation caused by idiopathic SGS after induction of anesthesia. further airway evaluation. If ventilation was impossible after airway manipulation, invasive airway management by tracheostomy may be unavoidable.(13) Key Words: Airway management, Difficult intubation, Subglottic stenosis Clinical signs of SGS are often subtle, and the diagnosis of a developing SGS can be very difficult. This case emphasizes that SGS can present without iatrogenic cause, especially in young to middle-aged women with respiratory symptoms. REFERENCES 1. Dedo HH, Catten MD. Idiopathic progressive subglottic stenosis: findings and treatment in 52 patients. Ann Otol Rhinol Laryngol 2001;110:305- ABSTRACT Unexpected Difficult Intubation Caused by Idiopathic Subglottic Stenosis 11. 2. Valdez TA, Shapshay SM. Idiopathic subglottic stenosis revisited. Ann Otol Rhinol Laryngol 2002; 111:690-5. 3. Gnagi SH, Howard BE, Anderson C, Lott DG. Joo Hyun Jun 1, Mi Hyun Lee 1, Eun Mi Choi 1, Eun Mi Kim 1, Young Ryong Choi 1, Pil Hyun Jeon 1, Seung Hwa Baek 1, Mi Hwa Chung 1, Sung Wook Park 2 1 Department of Anesthesiology and Pain Medicine, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, 2 Department of Anesthesiology and Pain Medicine, School of Medicine, Kyung Hee Medical University, Seoul, Korea A 44-year-old woman was scheduled to undergo an emergency laparoscopic operation for acute appendicitis. Her past medical history included chronic asthma (2 years prior) that was not treated with medication or inhaler. After inducing general anesthesia, a 6.5-mm internal diameter (ID) endotracheal tube (ETT) could not be advanced below the level of the vocal cords because of resistance, and a reattempt with a Idiopathic Subglottic and Tracheal Stenosis: A Survey of the Patient Experience. Ann Otol Rhinol Laryngol 2015;124:734-9. 4. Zaghi S, Alonso J, Orestes M, Kadin N, Hsu W, Berke G. Idiopathic Subglottic Stenosis: A Comparison of Tracheal Size. Ann Otol Rhinol Laryngol 2016;125:622-6. 5. Grillo HC. Management of idiopathic tracheal stenosis. Chest Surg Clin N Am 1996;6:811-8. 6. Nouraei SA, Sandhu GS. Outcome of a multimodality approach to the management of idiopathic subglottic stenosis. Laryngoscope 2013;123:2474-84. 7. Maldonado F, Loiselle A, Depew ZS, Edell ES, Ekbom DC, Malinchoc M, et al. Idiopathic subglottic stenosis: an evolving therapeutic algorithm. Laryngoscope 2014;124:498-503. - 29 -
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