Challenges in laryngeal mask ventilation: Case of a vocal cord polyp

Abstract

The most frequent causes of airway obstruction during the use of laryngeal mask airway (LMA) devices are related to a superficial plane of anesthesia or misposition. However, uncommon causes must also be considered. This case report presents a patient scheduled for elective surgery, encountering unexpected difficulties during airway management due to a previously undiagnosed giant vocal cord polyp. The steps for managing a difficult airway were followed correctly finally leading to awakening the patient to prevent a potentially dangerous “can’t intubate, can’t ventilate” scenario.

This case emphasizes the importance of thorough preoperative airway assessment, early recognition of airway difficulties and the strategic use of awake intubation techniques in complex airway management situations.

Highlights

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Vocal fold polyps are an uncommon, but possible cause of obstruction during anesthesia airway management.
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Hoarseness, vocal fatigue and dysphonia are signs indicating possible vocal cords abnormalities.
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If previously known, an adequate anesthetic management can be prepared.
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Direct or video laryngoscopy and fiberoptic bronchoscopy are essential tools to identify the cause of airway obstruction.
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Using a well-defined difficult airway management algorithm is key to ensuring a positive outcome in critical situations.

1 Introduction

Laryngeal mask airway (LMA) is a widely used supraglottic airway device for airway management during general anesthesia, especially in outpatient surgeries. Its rise in use is attributed to its its straightforward insertion, low invasiveness, and capacity to maintain effective ventilation without tracheal intubation [ ]. In anticipated difficult airway cases, LMA can guide the fiberscope (FBS), facilitating oxygenation, ventilation, and volatile anesthesia administration [ ]. However, its insertion is performed blindly and problems related to misposition or unnoticed glottic-subglottic obstruction may appear.

One such condition is the presence of large or obstructive lesions in the airway which can impair proper ventilation [ ]. There are several reported cases of difficult or impossible ventilation in patients with known polyps, but very few of previously undiagnosed polyps [ ]. It’s a rare but significant cause of difficult ventilation during general anesthesia and requires prompt and targeted interventions for effective anesthetic management [ ].

This case report details a challenging situation involving ventilation through an LMA obstructed by an undiagnosed giant vocal cord polyp.

2 Case presentation

A 53-year-old man with no significant medical history was scheduled for elective shoulder arthroscopy. Airway assessment showed a short thyromental distance and a Mallampati III. Body Mass Index was below 25 and no apparent symptoms of obstructive sleep apnea were reported.

Prior to general anesthesia induction with fentanyl and propofol, an interscalene brachial plexus block was performed. Non-invasive blood pressure, oxygen saturation, and electrocardiogram were continuously recorded. A size 5 LMA Unique® was inserted without difficulty using the standard technique after proper manual ventilation was verified. The correct positioning of the LMA was confirmed through lung auscultation and normal capnography waveform. However, upon initiating mechanical ventilation, elevated peak airway pressures (>30cm H2O) and an air leak at 24cm H2O were noted. Initially suspecting laryngospasm, muscle relaxation and deepening of anesthesia were attempted but no improvement was noted. A second LMA with gastric access was utilized to achieve a better seal, but difficult ventilation persisted, worsening over time. End-tidal CO2 levels increased to 55 mmHg, although oxygen saturation remained above 97 %.

Since a videolaryngoscope was not readily available a FBS was used to assess the LMA placement, revealing a large, previously undiagnosed white mass between the vocal cords ( Fig. 1 ). After an unsuccessful fiberoptic intubation through the LMA, the decision was made to awaken the patient to prevent a can’t-intubate-can’t-ventilate situation. Subsequently, an awake fiberoptic intubation was performed, revealing inflamed vocal cords and the mobile vocal cord polyp. A 7.5mm endotracheal tube with a soft silicone tip was successfully passed without further complications. A dose of 125mg of metilprednisolone was administered. After the surgery, the patient was carefully extubated in the operating room.