An Avulsed Tooth Detected Prior to Insertion of a Laryngeal Mask Airway

Abstract

This case report describes the importance of inspecting the hypopharynx via direct laryngoscopy prior to laryngeal mask airway (LMA) insertion during induction of general anesthesia for dental patients with special needs. A 51-year-old man with cerebral palsy underwent induction of general anesthesia for dental extractions and subsequently was noted to be missing a tooth. Prompt inspection of the airway via direct laryngoscopy revealed the tooth resting within the pharynx, which was subsequently retrieved, prior to insertion of the LMA. Visual inspection of the oropharynx and hypopharynx by laryngoscopy prior to LMA insertion can be useful in preventing accidental aspiration and ingestion of foreign bodies, particularly with certain high-risk patients. Use of laryngoscopy should also be considered if an object is lost or possibly impinging upon the airway.

A laryngeal mask airway (LMA) is a supraglottic airway device often used for patients receiving dental treatment under general anesthesia (GA).¹ The customary technique for placing an LMA after induction is performed by inserting the supraglottic airway device in a blind fashion, without prior or concurrent visualization of the posterior oropharynx and hypopharynx with a traditional or video laryngoscope. This approach is commonly utilized because of the ease of placing an LMA, which does not typically need the type of precise anatomic placement required with endotracheal intubation. However, blind insertion carries some inherent risks, such as potentially introducing a foreign body into the airway, subsequently causing inadvertent pulmonary aspiration or airway obstruction, or ingestion of the object. Airway obstruction due to foreign body aspiration during the induction of GA can have serious consequences, including significant morbidity and mortality. Furthermore, some patients with notable medical comorbidities or physical and/or mental disabilities may have a higher inherent risk of perioperative aspiration during anesthesia. For example, patients with cerebral palsy (CP) often may demonstrate retention or pooling of excessive quantities of oral secretions due to difficulty of swallowing. Additionally, some patients with intellectual disabilities (IDs) may retain food particles or foreign bodies in their mouths for extended periods of time. Finally, patients with dentition in poor repair are especially at risk for accidental fracture or avulsion of a tooth during the perioperative period. Therefore, in our institution, direct laryngoscopy is routinely performed before insertion of an LMA to ensure a patent airway, free of any foreign objects or debris.

The following is a case report wherein direct laryngoscopy was performed enabling retrieval of a tooth, which had become accidentally avulsed sometime during induction and mask ventilation, subsequently preventing the patient from aspirating or ingesting the tooth and ensuring the hypopharynx and airway remained unobstructed prior to inserting the supraglottic airway device.

CASE PRESENTATION

A 51-year-old male patient (height, 160 cm; weight, 45 kg; body mass index, 17.6 kg/m²) with CP presented to the hospital with complaints of pain and mobility involving the mandibular right first premolar and second molar. He had no other reported medical comorbidities or disabilities except athetoid CP with severe involuntary movements and slight intellectual impairment. While the patient did require use of a wheelchair for ambulation, there were no other appreciable concerns commonly associated with CP, such as muscle contractures, positional difficulties impacting the airway, suspected difficult intravenous (IV) access, or a history of aspiration or gastroesophageal reflux disease (GERD). The patient denied taking any medications and any history of food or drug allergies. The patient had undergone GA at this institution for dental treatment, including routine preventative care, restorative treatment, and extractions 4 times previously without complications. During the preceding dental visit, the attending dentist assessed the patient secondary to his complaints of pain, rendering a diagnosis of severe localized chronic periodontitis and recommending extraction of the offending teeth due to their poor prognosis. The patient was subsequently scheduled for another general anesthetic to facilitate the indicated dental treatment. The intended anesthetic plan developed for this patient consisted of an IV induction with mask ventilation, placement of a flexible LMA (LMA Flexible^™, Teleflex Medical, Co, Westmeath, Ireland), and maintenance via total intravenous anesthetic (TIVA) technique using propofol and remifentanil to help control his severe CP-related involuntary movements during the dental procedure. The patient had no appreciable contraindications for performing a laryngoscopy and utilizing a flexible LMA. There were no cervical range of motion limitations. His maximum interincisal opening was 7 cm, and the laryngoscopic grade (Cormack-Lehane classification) had been estimated as grade 1 during the last general anesthetic. However, neither the treating dentist nor the dental anesthesiologists in charge assessed the 2 teeth in question for being at high risk for avulsion prior to induction.

After completing the customary preoperative anesthetic evaluation and ensuring adherence to the NPO guidelines, the patient was taken to the treatment room. Anesthetic monitors were placed in the customary fashion, consisting of an electrocardiograph, pulse oximeter, noninvasive blood pressure cuff, capnography, and a skin temperature probe. A peripheral IV was started with a 22-gauge IV needle in the dorsum of the patient's right hand, and after preoxygenating the patient GA was induced with an IV bolus of propofol (135 mg), along with atropine sulfate (0.5 mg), and continuous infusions of propofol (85.2 μg/kg/min) and remifentanil hydrochloride (0.33 μg/kg/min). Although there was no difficulty ventilating the patient with the bag and mask, the anesthesiologist noticed the absence of the mandibular right first premolar (tooth #28) prior to the routine laryngoscopy. The tooth in question had been noted to be present during the preoperative assessment prior to induction of anesthesia by the attending dentist and the anesthesiologist, but no specific note was made regarding the degree of mobility. The anesthesiologist then inspected the oral cavity carefully and found all the other teeth present, except the missing premolar.

The avulsed tooth was presumed to have fallen into the oropharynx as it was not located elsewhere. Direct laryngoscopy was performed before inserting the LMA in order to try to locate and retrieve the tooth to ensure maintenance of a patent airway. While performing the direct laryngoscopy, the anesthesiologist noticed the avulsed tooth resting on the posterior wall of the hypopharynx. The anesthesiologist successfully retrieved the tooth with use of Magill forceps without any complications. After correct placement of the LMA, the surgery proceeded and the mandibular right second molar (tooth #31) was successfully extracted under GA maintained with continuous infusions of propofol (55.6–85.2 μg/kg/min) and remifentanil hydrochloride (0.033 μg/kg/min), plus supplemental air and oxygen at an Fio₂ of 50%. Local anesthesia via infiltration was performed with the use of 1.8 mL of 2% lidocaine (36 mg) containing 1 : 80,000 epinephrine (0.0225 mg). The continuous infusions were discontinued following conclusion of the surgical procedure, and the patient emerged in approximately 20 minutes without any complications. The patient was transferred to the ward, where he remained for 2 hours before being subsequently discharged from the hospital.

DISCUSSION

In this case, direct laryngoscopy was performed to locate an avulsed missing tooth prior to insertion of a supraglottic airway device, thereby preventing the possible accidental aspiration or ingestion of the tooth that had fallen into the posterior hypopharynx. If laryngoscopy had not been performed and the tooth not located and retrieved, insertion of the LMA might have introduced the tooth into esophagus or into the trachea, which could have been disastrous.

Although a laryngoscope may be used to facilitate ease of insertion of an LMA by pushing the tongue to the left side of the mouth,² direct laryngoscopy is not considered an essential step when placing an LMA. However, direct or indirect visual inspection of the airway, including the oropharynx and hypopharynx could be beneficial in selected clinical situations, such as prior to an anesthetic for those higher risk patient groups described previously.

Patients with CP often retain large volumes of secretions in the oropharynx. These patients may be unable to efficiently swallow oral secretions due to impaired muscle coordination and sensory perception difficulties³; this can lead to anterior and posterior drooling. During posterior drooling, secretions can migrate into the upper or lower airways when the patient is in the supine position. Thus, it is essential to remove any pooled secretions before insertion of a supraglottic airway device such as a LMA. Prompt suctioning immediately after induction of anesthesia can help maintain a clear and patent airway. Furthermore, patients with altered sensory function or disturbances, such as those with ID or autism, may have a history of retaining food in their mouth for extended periods of time. Additionally, patients with pica have a habit of eating nonnutritive objects, such as hair, stones, soil, and paper, and as such, they may hold or retain these foreign bodies in their mouths.⁴ For such patients, all objects and substances in the mouth and airway must be removed before the insertion of an LMA.

Aspiration of a tooth or a dental prosthesis during trauma and dental procedures has been reported in the literature.^5–7 Tooth aspiration during tracheal intubation is an uncommon, but well-known, complication that has been previously described.^8,9 Although there have been several case reports discussing the obstruction of an LMA during GA by foreign bodies, such as an ascaris or parasitic worm,¹⁰ a cleaning rod,¹¹ and white bread,¹² there have been relatively few reports of foreign body aspiration associated with the insertion of an LMA. In one case, a piece of plastic wrapping was inadvertently introduced into the airway during the insertion of an LMA.¹³ Therefore, this appears to be the first case report regarding the introduction of a fallen tooth into the airway or esophagus in association with insertion of an LMA.

Anticipating potential problems that may arise and developing appropriate management or contingency plans are critical aspects of any anesthetic plan. For a nonintubated patient, a misplaced foreign body occluding the airway is likely to cause sudden and serious deterioration of normal respiratory functionality. Whenever inclusion of a foreign body is suspected and cannot be immediately located, several steps should be considered. Early activation of emergency medical services or code team should be considered, particularly if the patient is unstable or if a thorough search on the oral cavity, nasal cavity, and pharynx proves unfruitful. The next step likely depends on the respiratory condition of the patient. If adequate ventilation is impaired, the anesthesiologist should consider following the guidelines for managing a difficult airway, such as the ASA Difficult Airway Algorithm. Once adequate ventilation is established, the foreign object can be retrieved under laryngoscopy or bronchoscopy after locating its position, often done with the help of radiographs CT scans, and/or bronchoscopy. In this particular case, failure to locate and retrieve the offending tooth would have prompted consultation with the appropriate emergency hospital staff to assist with the retrieval process following the aforementioned steps.

It is important to consider how anesthesiologists can prevent accidental aspiration or ingestion of a foreign body during an anesthetic. First, anesthesiologists should incorporate an assessment of the patient's airway as a key part of the preoperative physical assessment routine. Visual inspection of the oral cavity, looking for loose teeth, dental prostheses, jewelry, and other foreign items, is a critical aspect of this assessment. The anesthesiologist should also consider consulting with their dental colleagues regarding the patient's dental condition before beginning an anesthetic.^14–16 However, it must be stated that a precise preoperative oral examination by the anesthesiologist or dental team may be difficult or impossible in some circumstances, such as a patient with an ID who is extremely uncooperative.^17,18 It is also important to inquire with the patient's family or caregivers regarding any habits of holding food or foreign bodies in his/her mouth or any other notable conditions like loose teeth, dental prostheses, etc.

Second, anesthesiologists should consider performing a direct physical examination of the oral cavity and oropharynx immediately after administration of anesthetics, especially in those circumstances where such an evaluation was not possible beforehand. Incorporating careful suctioning of the airway is another useful step to ensuring airway patency but must be done carefully to avoid dislodgement or fracture of any teeth in poor repair. Oftentimes, prompt suctioning can be performed while simultaneously assessing the oral cavity and posterior oropharynx. If a foreign body or lost tooth is suspected, consideration should be given for visually assessing the airway. This can be performed using a traditional or video laryngoscope carefully and under sufficiently deepened anesthesia, to determine whether foreign bodies (including teeth) are present prior to inserting any type of airway device. Laryngoscopy is the definitive and most effective opportunity to identify pharyngeal or laryngeal foreign bodies. Based on this experience, we have begun to check the dentition of the patient prior to mask ventilation, immediately after the induction of anesthesia, and before insertion of an LMA, because the oral conditions might have changed after the preoperative assessment.

Use of an LMA is quite common in our institution when providing anesthetic care for patients with special needs because many of these patients frequently receive dental treatment under GA and use of a safe, effective, and minimally invasive anesthetic option is considered ideal. Most aspects of the dental treatment itself can be performed while using a flexible LMA. However, there are several circumstances where use of an LMA would likely be considered contraindicated, particularly situations with a higher risk of pulmonary aspiration in general, such as morbid obesity, elevated positive pressure ventilation, full stomach, etc.

CONCLUSION

In conclusion, thorough visual inspection of the oropharynx and hypopharynx by direct or indirect laryngoscopy prior to LMA insertion may be warranted and useful for preventing complications such as accidental aspiration and ingestion of foreign bodies, particularly for patients in which there is a high suspicion or likelihood of a foreign object being present that may impinge upon the airway.