Abstract
The anaesthetic management of patients presenting with laryngeal tumours and airway obstruction is difficult. We present the case of a pregnant woman at 30 weeks gestation who underwent surgical removal of two vocal cord polyps under general anaesthesia using jet ventilation

The anaesthetic management of patients presenting with laryngeal tumours and airway obstruction is difficult. Due to the physiological and anatomical changes associated with pregnancy, the anaesthetic care of the gravid patient requiring the resection of vocal cord pathology is even more challenging. The literature regarding anaesthesia for laryngeal surgery during pregnancy is limited, with no consensus regarding the ideal anaesthetic approach [1] [2] [3] [4] [5] .

We present the case of a woman at 30 weeks gestation who underwent surgical removal of two vocal cord polyps under general anaesthesia utilising jet ventilation.
CASE HISTORY
Written consent to publish this case was obtained from the patient.
CASE HISTORY
A 32-year-old, 82 kg, gravida 3, para 1 pregnant woman at 30 weeks gestation presented with progressive shortness of breath, dysphagia and hoarseness over one week following an upper respiratory tract infection. Her medical history was notable for obstructive sleep apnoea requiring continuous positive airway pressure and an elevated factor VIII level treated with subcutaneous dalteparin 5000 U/day. Physical examination on admission showed unlaboured breathing at 18 breaths per minute, oxygen saturation of 97% on room air and a Mallampati class I view with normal mouth opening and neck flexibility. Transnasal fibreoptic laryngoscopy performed by the otolaryngologist revealed oedema of the glottis and erythema of the vocal cords suggesting acute glottitis. She was therefore admitted to the intensive care unit. Despite the administration of intravenous ampicillin 1 g sixhourly and dexamethasone 4 mg 12-hourly, her symptoms did not improve over the next two days. She continued to have episodes of throat tightness and shortness of breath but her vital signs remained normal, with oxygen saturation readings of 99% on room air.
CASE HISTORY
Subsequent laryngeal re-assessment demonstrated progressive oedema, extending to the epiglottis, supraglottis and vocal cords, with incomplete cord closure on phonation. High humidity oxygen was administered and antibiotic therapy changed to ceftriaxone 2 g per day. On the third day after admission to the intensive care unit, the patient's symptoms worsened; she was unable to lie flat and she developed severe dysphagia. Her respiratory rate increased to 22 breaths per minute, with an oxygen saturation of 96% on 30% high humidity oxygen mask. A repeat nasendoscopy revealed a floppy polypoidal mass on the right vocal cord with decreased mobility and erythema of the supraglottis suggesting right vocal cord pyogenic granuloma of pregnancy. The patient was therefore scheduled to undergo elective resection of the vocal cord polyp.
CASE HISTORY
After a fasting period of 12 hours she received oral pantoprazole 40 mg, sodium citrate 30 ml and intravenous metoclopramide 10 mg. Standard anaesthetic monitors and an external foetal heart rate monitor were applied. The patient was positioned supine, with left uterine displacement, in approximately 30 degrees reverse Trendelenburg position. Following pre-oxygenation for five minutes, rapid sequence induction with cricoid pressure was performed using propofol 180 mg and suxamethonium 160 mg. Direct laryngoscopy showed
Case RepoRt
Anaesthesia and Intensive Care, Vol. 39, No. 6, November 2011 a grade I view and an obstructing lesion at the level of the vocal fold. The trachea was intubated with a Hunsaker Mon-Jet ventilation tube (Xomed, Medtronic) and jet ventilation was started using the Bivona Carden intermittent jetting device. An inspired oxygen fraction of 40 to 50% was given except when the laser was used, when we switched to air. Ventilation was performed manually at a rate of 8 to 12 breaths per minute, allowing sufficient time for expiration. The adequacy of ventilation was judged by intermittent verification of bilateral air entry by auscultation and observation of bilateral chest expansions. Air leak around the tube was confirmed to permit expiration. General anaesthesia was maintained using propofol 120 μg/kg/minute and remifentanil 30 to 50 μg per hour. Muscle relaxation was achieved using increments of rocuronium. Oxygen saturation was maintained at 97 to 98% and end-tidal carbon dioxide (CO 2 ) at 30 to 35 mmHg. Using CO 2 laser technology the surgeon resected a friable, smooth right posterior glottic mass (1.4×1.4×0.6 cm) and a small left anterior mass (0.3×0.2×0.1 cm), respectively. After resection and haemostasis, the Hunsaker tube was replaced by a 7.0 mm endotracheal tube. Intravenous anaesthesia was discontinued and the patient's trachea was extubated. The procedure lasted for one hour and was well-tolerated. In the postoperative period, the patient required three boluses of intravenous fentanyl 12.5 μg for pain control. The foetal heart rate and uterine monitoring was continued for 24 hours without showing evidence of foetal distress or preterm labour. The patient's postoperative course was uneventful and she was discharged home, asymptomatic, on postoperative day three. She returned eight weeks later for an elective caesarean section and delivered a healthy baby.
Case RepoRt
Pathological examination of the two resected specimens showed fragments of allergic type mucus with no evidence of fungus on Grocott stains.
DISCUSSION
The management of patients undergoing laryngeal surgery is a significant challenge for surgeons and anaesthetists. The physiological and anatomical changes associated with pregnancy and the need to monitor foetal wellbeing make the anaesthetic care of the gravid patient with vocal cord lesions problematic.
DISCUSSION
The third trimester of pregnancy is associated with an increased risk of gastric acid aspiration, diminished pulmonary functional residual capacity and increased oxygen consumption 6 . These changes relatively contraindicate general anaesthesia techniques that allow spontaneous ventilation with an unprotected airway. General anaesthesia in pregnancy usually mandates controlled positive pressure ventilation facilitated by cuffed tubes placed in the trachea, either awake using a bronchoscope or under general anaesthesia following rapid sequence induction. In the present case we suspected difficulty with the insertion of a size 5.0 microlaryngeal cuffed tube through the small laryngeal opening. We were concerned that endotracheal intubation might avulse the polyp and push it more distally, raising the risk of a ball-valve effect lower in the airway or bleeding. Consequently we opted to rapidly induce general anaesthesia and ventilate the patient's lungs using the Hunsaker Mon-jet tube, as described elsewhere 7 . Because the patient's supraglottic airway appeared unremarkable and the polyps had been visualised previously by transnasal fibreoptic laryngoscopy, we were confident about achieving immediate access to the glottis using direct laryngoscopy.
DISCUSSION
To reduce the risk of aspiration we paid particular attention to the appropriate period of preoperative fasting, timely administration of antacid prophylaxis and positioning of the patient.
DISCUSSION
The Hunsaker Mon-jet tube is 35.5 cm long with a maximum outer diameter of 2.7 mm. The tube is made of a nonflammable fluoroplastic material, rendering it laser safe. A metal stylet provides the rigidity, yet enough flexibility to facilitate tracheal intubation. The basket at the distal end self-centres the tube within the trachea, preventing the jet port from coming into contact with the mucosa. A monitoring port with a 1 mm inner diameter opens 3.2 cm above the jet port and is attached proximally to a Luer-lock adapter and a three-way stopcock. Subglottic jet ventilation during laryngoscopy provides the advantage of ventilation, with the possibility of venting blood and debris outwards without major movement of the vocal cords and limiting visualisation for the surgeon. The major complication of jet ventilation is barotrauma due to raised intrathoracic pressure, resulting from either outflow obstruction or excessive inspiratory pressure [8] [9] [10] . To minimise the risk of barotrauma we used a device equipped with a reducing valve, a manometer for pressure control and ensured at all times that an oral airway was placed to allow egress of exhaled air. Modern jet ventilators are equipped with a pressure-triggered automatic shut-off that precludes the generation of uncontrolled peak airway pressure. The use of such a machine would have been safer but these were not available in our institute. We used low-frequency jet ventilation because it has been shown that, in most cases, adequate gas exchange can be maintained with lowfrequency subglottic jet ventilation 11, 12 . Moreover, monitoring of end-tidal CO 2 is only possible during low-frequency jet ventilation, high frequency jet ventilation is relatively ineffective in removing CO 2 and various measures may be employed to avoid CO 2 retention 13 . Recent publications have demonstrated the efficacy and safety of jet ventilation in patients with a difficult or partially occluded airway 14 . Its use for morbidly obese patients and in patients with poor chest compliance has been described 15 but this case is, to our knowledge, the first in which the Hunsaker Mon-jet tube ventilation was used successfully as part of the anaesthetic management of a woman in the third trimester of pregnancy.

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