Subcutaneous Emphysema: Dental Causes and Management

Introduction

Subcutaneous emphysema is a well-known complication that can occur during dental procedures. It arises when air is forcefully pushed into the submucosal spaces, leading to tissue distension. This trapping of air can progressively spread through the facial spaces, which are anatomical regions of loose connective tissue between muscles and bones. The consequences of subcutaneous emphysema may be profound. Life-threatening complications can be avoided by diligent diagnosis and management.

Subcutaneous emphysema and dentistry
The oral cavity is a particularly susceptible location for the initiation of subcutaneous emphysema as a multitude of dental procedures involve soft tissue manipulation. The most common iatrogenic cause of subcutaneous facial emphysema is the use of air-driven handpieces during tooth extraction.¹ Tooth sectioning and bone troughing, in combination with a raised mucosal flap, exposes a space between the periosteum and the bone where air may become entrapped.

Other dental causes of subcutaneous emphysema have been reported in literature. Patients with periodontal disease and minimally attached gingiva are at an increased risk of subcutaneous emphysema during routine restorative and endodontic procedures.² Cavity preparation using air-driven handpieces or air-water syringes for buccal lesions may push air into these pathological periodontal tissue spaces. Reports of subcutaneous emphysema have also followed the use of gingival retraction cords, as the pressure from cord packing may cleave gingival attachment.³ The use of air-cooled lasers accounts for roughly 15% of reported subcutaneous facial emphysema cases in dentistry.¹ It is evident that even with strict preventative measures, patients are still at risk of this complication. Therefore, it is prudent to understand the pathophysiology, management, and sequelae of subcutaneous emphysema to avoid dangerous complications.

Subcutaneous facial emphysema usually follows an indolent course.¹ In rare instances, air may accumulate and spread into facial spaces.⁴ This poses the greatest risk when the offending air source is located at a site near the mandibular molars, as air may be forced into the buccal, submandibular, and sublingual spaces.⁴ Air in these areas can quickly spread into the neck and retropharyngeal space, which communicates directly with the mediastinum and thoracic cavity.⁵ Pressure in these anatomical spaces has been reported to cause respiratory arrest and cardiac dysrhythmias.⁶

Signs, symptoms, and differential diagnosis
The first sign of subcutaneous emphysema may be readily evident as either immediate or delayed tissue swelling.⁷ Unfortunately, many other complications of dental work may present with similar symptoms as subcutaneous emphysema. Rapid swelling may result from a hypersensitivity reaction, anaphylaxis, angioedema, or a hematoma.⁸ If swelling is delayed, this reaction may be mistaken for bacterial infections such as cellulitis or necrotizing fasciitis.⁹ Considering this list of differentials, the distinction of subcutaneous emphysema can usually be made by judicious palpation. One can be almost certain that subcutaneous emphysema is present if crepitus or crackles are felt when palpating the swollen tissues.¹ This can also be differentiated from other diagnoses as the swelling is soft on palpation and usually lacks the warmth and erythema noted in either hypersensitivity reactions, cellulitis, and hematomas.¹ It is unlikely for subcutaneous emphysema to present with systemic symptoms such as fever, although there are reports of infections following bacteria spread from oral tissues into these spaces.¹

If subcutaneous emphysema is suspected, careful inspection and examination must be undertaken. The operator must ensure that tissue swelling is not progressively worsening. As well, care must be taken to evaluate any spread to dangerous anatomic cavities. Changes in vision, voice, swallowing, breathing abilities, consciousness, or chest pain are immediate signs that the patient should be transferred to an emergency room.¹⁰ Caution is required as there have been reports of blindness as a result of nerve compression from subcutaneous emphysema as well as ischemic eye injuries from air emboli.¹¹ Subcutaneous air accumulation in the neck can also cause swelling of the oropharynx and occlude the trachea. Signs of spread to the thoracic cavity indicate a risk of pneumothorax, lung collapse, or cardiovascular involvement.10 Substantial air accumulation can also result in air embolisms of the brain or heart, two life threatening medical emergencies.¹² Due to the significant potential for harm, any indications of subcutaneous emphysema, even those more minor in nature, should be treated with caution.

Management
While subcutaneous emphysema may pose a serious health concern, the most common course is usually self-limiting and can be managed conservatively. If subcutaneous emphysema is suspected, patients should be monitored for signs of respiratory distress prior to discharge. There is also literature supporting the use of broad-spectrum antibiotics to help prevent infection from oral bacteria introduced into the submucosal tissues.¹³ In the literature, roughly 50% of operators have administered antibiotics to patients with subcutaneous facial emphysema, although, there are no clinically significant differences in outcomes.¹³ Other literature suggests the prescription of corticosteroids to reduce the risk of swelling, however, the benefits of this intervention are also inconclusive.¹³ Life-threatening cases of subcutaneous emphysema may require surgical intervention and drainage via infraclavicular incisions.⁷ Under these circumstances, ongoing medical care is necessary and patients must be admitted to a hospital.

Care should be taken to avoid increases in intraoral pressure which may further expand tissue spaces. Patients should be advised to avoid smoking, nose blowing, and the use of straws.¹³ Analgesics such as acetaminophen or ibuprofen may also be used to manage discomfort.¹³

The recovery from subcutaneous facial emphysema typically takes approximately seven days.¹ Within this period, air within the tissue spaces is absorbed into the bloodstream and eliminated by the lungs. More specifically, swelling begins to resolve within two to three days and complete clinical resolution may be seen after seven to ten days.¹

Conclusion
Subcutaneous emphysema is a potentially life-threatening complication that can occur during routine dental procedures. Operators must correctly identify signs and symptoms of this situation, in addition to actively responding to dangerous facial space involvement. Patients suffering from localized lesions should receive affirming reassurance and prolonged monitoring prior to discharge. In some cases, open mucosal lesions allow for bacterial penetration and patients may benefit from a course of antibiotics. Operators must evaluate for signs of serious complications such as vision loss, as well as difficulty breathing or chest pain, which would require immediate transfer to an emergency medical facility. Appropriate identification and management of subcutaneous emphysema in a dental office will benefit the outcomes of affected patients.

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References

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About the Author

Dr. Lucia Santos is a current first-year dental anesthesiology resident at the University of Toronto, where she had previously completed her Doctor of Dental Surgery degree. She is also conducting research at the Hospital for Sick Children (SickKids) where she focuses on neonatal pain management. She can be reached at lucia.santos@mail.utoronto.ca.

Read more articles from the 2022 Dental Pharmacology & Anesthesia issue of Oral Health.