The incidence, clinical features, and risk factors for postoperative retropharyngeal hematoma and related dyspnea following anterior cervical discectomy and fusion: a single-center study of 10,615 patients.

Background Context: Postoperative retropharyngeal hematoma (PRH) and related dyspnea are rare but life-threatening complications following anterior cervical discectomy and fusion (ACDF) that require urgent recognition and treatment. However, current knowledge of PRH after ACDF is limited. Meanwhile, whether the morphological features of upper airway are the risk factors of PRH remains unknown.

Purpose: The study aimed to investigate the incidence, clinical features, and risk factors, especially the morphological features of upper airway, of PRH and related dyspnea following ACDF.

Study Design: A nested case‒control study.

Patient Sample: Consecutive patients who underwent ACDF at a single institute from January 2010 to December 2021 were retrospectively reviewed.

Outcome Measures: The outcome measures included the incidence, clinical features, intervention, outcome and risk factors for PRH and related dyspnea.

Methods: All patients with PRH were classified into the hematoma group. For each PRH subject, 3 control subjects without PRH were randomly selected as the control group. The clinical features, interventions and outcomes of patients were described. Potential risk factors were evaluated, including demographics, comorbidities, surgical characteristics, coagulation function, blood loss, preoperative blood pressure, and the morphological features of upper airway [prevertebral soft tissue thickness (PVT) and location of transverse arytenoid muscle (TAM) and epiglottis]. Univariate tests and multivariable logistic regression analysis were used to determine the risk factors for PRH. Subgroup analysis was also conducted for PRH patients with and without dyspnea.

Results: Among the 10615 patients who underwent ACDF, 18 (0.17%) developed PRH. The median time from the index surgery to PRH formation was 8.5 hours (25 and 75 percentile: 4 hours to 24 hours). All the PRH patients initially presented with wound swelling. Twelve (0.11%) patients presented dyspnea due to PRH, 2 of whom received urgent intubation and 1 of whom received emergent tracheotomy. All patients underwent hematoma evacuation, and most of them presented with completely relieved symptoms after evacuation, except for 1 patient who died from ischemic hypoxic encephalopathy. A level between the epiglottis and the TAM (LET) greater than 2, ossification of posterior longitudinal ligament (OPLL) and higher diastolic blood pressure (DBP) before surgery were found to be risk factors for PRH formation. Subgroup analysis revealed that a smaller prevertebral soft tissue thickness at C5 was associated with the development of dyspnea.

Conclusion: This study is the largest study to date focusing on the PRH and related dyspnea after ACDF. Our study showed that the incidences of PRH and related dyspnea after ACDF were 0.17% and 0.11%, respectively. The predominant symptoms of PRH were wound swelling and acute dyspnea. Most PRH cases occurred in the acute postoperative period. We demonstrated the risk factors for PRH to be (1) OPLL, (2) LET≥2 and (3) higher DBP before surgery and advocate paying increased attention to upper airway morphological features for identifying the risk of PRH after ACDF. With urgent recognition and timely intervention, severe clinical outcomes could be avoided.