There have been many factors identified that may potentially contribute to postoperative airway obstruction following cervical spine surgery. These factors can be divided into patient characteristics and intraoperative events that can cause swelling of the larynx and/or prevertebral space leading to airway compromise.

Patient characteristics that have been identified as risk factors for airway compromise include obesity, chronic obstructive pulmonary disease, asthma, smoking, and prior anterior cervical spine surgery. Risk factors related to the procedure and intraoperative events that have been linked to postoperative airway compromise include cerebrospinal fluid leak, hardware or bone graft displacement, postoperative abscess formation, surgical time greater than 5 hours, blood loss greater than 300 mL, surgical procedures involving three or more vertebral levels, and surgeries requiring greater than 4 units of transfused blood (2,3). Postoperative excessive tongue swelling may also contribute to postoperative airway obstruction.

Suk et al. (4) performed a prospective study to evaluate soft tissue swelling following anterior discectomy and fusion (ACDF) procedures. The authors found that peak swelling usually occurred around postoperative day 2 and 3. Also, more swelling occurred between the C2-C4 vertebral levels as compared to below the C5 level. The tendency for swelling to occur more commonly in the upper cervical spine has been further validated in a radiographic study by Andrew and Sidhu (5). In their study, 32 patients undergoing a 1- or 2-level ACDF procedure underwent cervical radiographic analysis postoperatively. Measurements were taken from the anterior vertebral body border of the cervical spine to the posterior aspect of the airway (prevertebral and pretracheal soft tissue spaces) from C2-T1, and the postoperative differences were measured. The greatest level of prevertebral soft tissue swelling occurred at the midbody of C4 with a maximum of 24 mm of swelling found in one patient. Normal prevertebral and pretracheal soft tissue spaces are between 11 to 12 mm and 20 to 26 mm, respectively.

Ankylosing spondylitis (AS) has also been shown to contribute to potential airway compromise. In a case report by Krnacik and Heggeness (6), a patient with AS undergoing excision of an osteophyte that was compressing the esophagus developed severe angioedema requiring emergent reintubation and eventual tracheostomy.

Postoperative hematoma formation causing respiratory distress is a worrisome complication for patients undergoing anterior neck surgeries for vascular, orthopaedic, neurosurgical, and other oral and pharyngeal conditions. Hematoma formation has been described to occur between 0.2% and 1.9% of patients resulting in airway compromise following anterior cervical spine surgery (1,7,8). The etiology of hematoma formation relates to continued postoperative venous and arterial bleeding. Hematomas can occur despite postoperative drain placement. Vomiting and coughing can increase venous pressure leading to further bleeding. Additionally,
uncontrolled increases in blood pressure, underlying coagulopathy, and the use of anticoagulant medications may all precipitate a hematoma. Therefore, blood pressure should be controlled pharmacologically, and the use of anticoagulants for the prevention of deep venous thrombosis and pulmonary embolus should be used with caution. Postoperative hematoma formation causing respiratory distress requires urgent incision and drainage at the bedside or in the operative room.