Airway resistance and airflow dynamics after fat injection into vocal folds

Objectives: The aim of this prospective study was to verify whether vocal fold fat augmentation (VFFA) modifies upper airway patency. To the best of our knowledge, this is the first study analyzing the impact of VFFA on laryngeal resistance to airflow. Methods: Twenty-one consecutive patients 16 to 74 years of age underwent 24 VFFA operations because of glottic incompetence due to laryngeal hemiplegia (13 patients) or vocal fold tissue defects (8 patients). Flow-volume loop spirometry and body plethysmography were performed before and 1 to 6 months after surgery. Results: There were no significant differences between preoperative and postoperative pulmonary volumes (FVC and FEV1), expiratory flows (PEF, FEF50), or inspiratory flows (PIF, FIF50), although a slight increase in inspiratory flows meant that FEF50/FIF50 slightly decreased. Specific airway resistance (sRaw) increased after VFFA, but not in a statistically significant manner (p = .078). None of the patients experienced postoperative stridor. One obese woman with laryngeal hemiplegia had postoperative effort dyspnea; her respiratory studies showed a reduction in inspiratory flows and an increase in sRaw, and demonstrated progressive improvement. Conclusions: Flow-volume loop spirometry showed that VFFA does not significantly modify respiratory airflows, although a slight increase of inspiratory airflows suggested an improvement in variable extrathoracic obstruction. Body plethysmography proved to be a sensitive procedure that highlighted the subtle increase in upper airway resistance. Hence, VFFA can be considered a relatively safe procedure for achieving vocal fold medialization, and spirometry and plethysmography can be useful for preoperative assessment and postoperative follow-up.