Awake Fiberoptic Intubation Using Dexmedetomidine in a Compromised Airway Secondary to a Thyroid Carcinoma
Rebecca A. Ruffle DO*, Shaheen Shaikh MD*, Daniel Kim, MD‡
*Department of Anesthesiology, ‡Department of Otolaryngology, University of Massachusetts, Worcester, MA, USA
|In this case report we present a case of inoperable thyroid carcinoma causing airway compression presenting with paraplegia with bladder and bowel dysfunction for urgent decompression.The patient was a 69 year old male with significant past medical history of asthma, hypertension, coronary artery disease, and type II diabetes who presented with four weeks of progressive lower extremity weakness, low back pain, loss of sensation to the bilateral lower extremity and difficulty voiding. The patient had a history of thyroid carcinoma with attempted resection but the procedure had to be aborted after a biopsy since the blood loss exceeded 1,800 mL. The biopsy revealed a follicular carcinoma of the thyroid.He now presented with metastasis in his spine causing spinal cord compression. An MRI done at the time of admission showed a mass at T10 with significant spinal cord stenosis and compression at the level of T9-T10 (Figure 1). The patient was scheduled for urgent T8-T12 laminectomy, excision of T10 metastatic mass and fusion of T8-T10 vertebral bodies. The surgery was scheduled for 7 hours.|
|A perioperative consultation by the anesthesia team was obtained prior to surgery with the preoperative diagnosis of metastatic follicular cell carcinoma to the spine with severe spinal cord compression, paraparesis and sphincter dysfunction. Evaluation by the anesthesia team revealed concerns about the airway, intraoperative blood loss, hypotension in the prone position, and vision loss.Since the prior attempt to resection the primary tumor resulted in significant blood loss, the patient was taken preoperatively for spinal angiography and embolization of the spine tumor. During this procedure, a hypervascular tumor involving the T10 vertebral body with left paraspinal extension supplied by the left T10, T11, and right T10 intercostal arteries was identified. The hypervascular tumor was successfully devascularized. This procedure was done with sedation and local anesthesia and there were no complications.Physical examination of the neck revealed a large hard, lobulated, nontender mass extending bilaterally over the region of the carotid arties. The carotid artery pulses were diminished and neck anatomy was obscured by the tumor. A well healed incisional scar extended from the posterior border of the sternocleidomastoid muscle from left to right. We therefore decided not to place an internal jugular central line for fluid resuscitation during this case. Two 18-gauge peripheral intravenous lines and a radial arterial line were inserted preoperatively.|
|Evaluation of the patient’s airway revealed a Mallampati score of 2 and a thyromental distance of two finger breaths. The patient had normal mouth opening and neck mobility. He did not have stridor, difficulty breathing or difficulty swallowing. He had a history of reactive airway disease and reported using his Combivent inhaler only 2-3 times per year with no recent asthma attacks. He had never been hospitalized for his asthma. MRI showed a large mass in the left lobe of the thyroid gland with compression and deviation of the trachea to the right. The trachea was narrowed with dimensions of 14 mm in anterior posterior diameter and 8 mm in transverse diameter. After evaluation of the airway an awake fiberoptic intubation was planned.|
|Standard ASA monitors were applied. He was given glycopyrolate 0.3 mg IV to decrease oral secretions and midazolam 2 mg IV for anxiolysis. The patient was given 5 ml of 4% lidocaine nebulized over 10 minutes and 4% viscous lidocaine gargles, 5ml each X2. Vital signs were stable. He was then taken to the operating room. Oxygen was delivered vial nasal cannula. The patient was positioned in a beach chair/semi-sitting position on the stretcher. Dexmedetomidine 1 mcg/kg bolus was administered over 10 minutes followed by an infusion at 0.3 mcg/kg/min. The gag reflex was absent. An oral Berman airway was placed in the patient’s mouth. A fiberoptic bronchoscope was used for intubation. Vocal were cords visualized and a 7.5 mm oral endotracheal tube was placed with no obstruction or difficulty on the first attempt. The endotracheal tube position was confirmed with bilateral chest rise, equal bilateral breath sounds, and end-tidal carbon dioxide monitoring. General anesthesia was then induced.The patient was placed in the prone position on the Jackson table with the endotracheal tube position once again confirmed, the eyes were free, and pressure points were well padded.The surgery proceeded with excision of a large extradural metastatic tumor from the epidural space to the vertebral bodies and pedicles and surrounding soft tissues. Posterior fusion was done from T8-T12 using allograft bone and segmental fixation. The surgery lasted 6 hours. Arterial blood gases were obtained at regular intervals for blood gases, electrolytes, hematocrit, and hemoglobin. The mean arterial pressure was maintained between 70-75 mm Hg. During the procedure the estimated blood loss was 800 mL. The eyes and pressure points were checked every fifteen minutes. The patient was turned supine, cuff leak was present, and the patient was extubated when awake, breathing spontaneously, and following commands. He was brought to the post- anesthesia care unit for postoperative monitoring.|
|The patient was followed by the neurosurgery and anesthesia teams. He was continued on dexamethasone, insulin sliding scale for blood sugar control, and preoperative medications. Sensation was present bilaterally in the lower extremities and deep tendon reflexes were absent.|
|This case illustrates the challenges of endotracheal intubation in a patient with a thyroid carcinoma. Airway management is a crucial element in the preoperative planning by the anesthesiologist. Failed intubation is associated with serious complications (5). This patient’s initial evaluation revealed normal mouth opening, a Mallampati score of 2, absence of a short neck, normal neck mobility and thyromental distance of two finger breaths. On physical exam this patient’s thyroid mass distorted the anatomy of the external structures of the neck. MRI showed both tracheal deviation and compression of the trachea.When a goiter is accompanied by airway deformity, the patient it at risk for difficult direct laryngoscopy and intubation (2). Studies have shown that it is not the large size of a goiter that is associated with a higher degree of difficulty intubating, rather, the presence of a cancerous goiter is a major risk factor in predicting difficult endotracheal intubation (1). Difficult intubation of the trachea in these patients is caused both by carcinoma and associated tissue invasion and fibrosis (1). Tissue invasion changes the physical anatomy of the structures and fibrosis may reduce mobility making direct laryngoscopic view difficult (1). Awake fiberoptic intubation remains the gold standard for anticipated difficult intubation in such patients (3). The role of sitting fiberoptic bronchoscopy has been discussed with great success in the setting of thyroid tumors (4). In this case we chose the sitting position to decrease compression and occlusion of the airway from structures of the oropharynx.Fiberoptic bronchoscopy and tracheal intubation is challenging in an awake patient. The patient was prepared with topical anesthesia to decrease airway sensation. Then the patient was given midazolam for anxiolysis and glycopyrolate for its antisialogogue properties. Dexmedetomidine was selected for both its anxiolytic and antisialogogue properties, but most importantly because it is asedative that causes minimal respiratory depression (7).Dexmedetomidine is a selective alpha-2 agonist. It produces sedation via activation of postsynaptic alpha-2 receptors in the locus coeruleus that regulate wakefulness (6). We found that dexmedetomidine provided a moderate level of sedation without causing respiratory distress or hemodynamic instability. The patient was sleepy but easily aroused. He was cooperative and easy to communicate with. The dexmedetomidine infusion allowed us to safely perform fiberoptic bronchoscopy and tracheal intubation on the first attempt.In conclusion, we found that dexmedetomine is a useful agent for sedation during awake, sitting, fiberoptic intubation of the difficult airway. It provided minimal respiratory impairment and adequate sedation and anxiolysis.|
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