Teaching Case

An 85-year-old man was admitted to the intensive care unit with respiratory failure requiring ventilatory support (Fig. 1). Non-invasive positive pressure ventilation (NiPPV) was started with a full-face mask. During admission the patient’s condition deteriorated and tracheal intubation was required. Tracheal intubation was unexpectedly difficult due to an obstruction.

Chest radiograph upon admission showed a pleural effusion on the right with lower lobe volume loss. The perihilar vasculature was accentuated on both sides (Fig. 1).
The patient's condition deteriorated and a 4 day follow-up chest radiograph showed an increase of the pleural effusion and volume loss of the right lung, suggestive of increased obstruction (Fig. 2).
A radiograph of the upper chest and neck obtained after the difficult tracheal intubation showed that the tube was correctly positioned and a foreign body was situated in the oropharynx (Fig. 3).
A flexible fiberoptic laryngoscopy was performed and a dental prosthesis was atraumatically retracted. The dental prosthesis with 3 molar teeth fitted in a small metal plate (5×3 cm) appeared to have been dislodged from the left upper cheek (Fig. 4).
In retrospect, the foreign body in our patient could already have been detected on the chest radiograph prior to the intubation (Fig. 2).

Background
Management of a difficult airway is challenging for intensivists on an intensive care unit as this could have fatal consequences. Precise data on the incidence of a difficult airway intubation are not clear [1].

Clinical perspective
A difficult intubation can be defined as one that requires multiple or prolonged attempts, multiple operators, multiple intubating devices or excessive lifting force; it can also be defined as one that is performed with a poor view of the vocal cords [1]. Factors related to difficult tracheal intubation increase with age [1]. In elderly patients difficult tracheal intubation is often due to low head and neck movement, a short thyromental distance and poor dentition [1]. Loose crowns and bridges are a well-known cause of difficult airway management, especially in the elderly. However, cases involving dislocated fixed dental prostheses are rare [1].

Imaging perspective
Chest radiographs on an intensive care unit are made on a daily basis [2]. Especially chest radiography after endotracheal tube placement is still known to be a necessity [3], but more attention should be focussed on the role of chest radiographs prior to intubation [1].

Outcome
In this case a chest radiograph was performed to elucidate the cause of the unexpected difficult airway intubation. This radiograph showed a foreign body situated in the oropharynx. A fixed dental prosthesis appeared to have been dislodged from the upper cheek and was removed. After this intervention, the patient could be treated successfully.

Take home message
The foreign body in our patient could already have been detected on previous chest radiographs; however, the difficulty of discerning an unknown foreign body on a standard chest radiograph may have hampered early diagnosis. We hypothesize that the tight fitting straps of the NiPPV mask and delirium-related restlessness and agitation of the patient contributed to the dislodgement and displacement of the dental prosthesis.
This case report shows that chest radiographs are helpful in elucidating airway complications and detecting coincidental conditions prior to intubation. A thorough inspection of previous chest radiographs can provide clues regarding the cause of difficult airway management. In all suspected difficult airway intubations a chest radiograph should be considered.