Can oxymetazoline simulate the outcomes of septoplasty and inferior turbinate reduction surgery?

Abstract

Inferior turbinate hypertrophy (ITH), with or without nasal septum deviation, is among the most common surgically correctable etiologies of nasal obstruction.1 The current challenge associated with surgical decision is twofold: 1) there are significant variabilities in individual nasal anamtomies as well as in surgical techniques; 2) there are few objective measures to identify which patients would benefit from surgery.2, 3 A patient's responsiveness to oxymetazoline has been often used as a proxy for surgical candidacy.3 Oxymetazoline is a selective α1 adrenergic receptor agonist and α2 adrenergic receptor partial agonist, which causes vasoconstriction and results in nasal decongestion since the soft tissue of the turbinates is rich in venous sinusoids and seromucinous glands. Yet despite the ubiquitous use of this bedside test, there are limited data that objectively compare the effect of oxymetazoline versus surgery on nasal morphology and aerodynamics, and whether such an approach could be used to predict patient outcomes. This study uses computational fluid dynamics (CFD) modeling to examine the changes in nasal aerodynamics and resistance in one patient after administration of oxymetazoline nasal spray as well as after inferior turbinate reduction surgery, to preliminarily investigate whether the changes in these factors are similar between the two and can corroborate the degree of symptomatic improvement. The patient is a 39-year-old male with moderate bilateral ITH and septal deviation resulting in nasal obstructive symptoms refractory to topical intranasal steroids. He denied history of chronic rhinosinusitis, allergies, head trauma, or autoimmune/connective tissue disorders. The patient completed the NOSE, SNOT-22, and Visual Analog Scales (VAS) for nasal obstruction (0: completely clear, 10: completely obstructed) immediately before his baseline computed tomography (CT) scan. To rule out placebo effect, a single-blinded sham test was performed with saline solution prior to oxymetazoline administration. Saline was topically applied via nasal spray followed by a 30 min rest and reassessment of symptoms (VAS and NOSE score). After the sham test, topical oxymetazoline spray was applied with symptom reassessment after a 30 min rest. A second CT scan then immediately followed. The patient ultimately underwent bilateral inferior turbinate reduction as well as minor septoplasty to remove a septal spur, with postoperative assessment after 8 weeks. Three-dimensional CFD models were constructed using the described method5 based on cone beam CT scans (3D Accuitomo 170, J. Morita USA, Inc.) at three time points: baseline, 30 min after oxymetazoline, and 8 weeks after surgery. Airflow patterns and velocity changes throughout the nasal airway were simulated under quasi-steady restful breathing conditions (15 Pa pressure drop between the nostrils and the nasal pharynx at a room air temperature of 20°C) using CFD software (ANSYS Fluent 19.2, Ansys, Inc, Canonsburg, PA). The numerical method and meshing protocol applied in this study have been previously validated against experimental measurements.4 The patient reported significant symptomatic improvement after both oxymetazoline and surgery. The NOSE score decreased from 80 at baseline and 80 after the sham test to 35 after oxymetazoline spray and 30 at 8 weeks after surgery. Likewise, VAS ratings of nasal obstruction decreased from 7 at baseline, to 6 after the sham test, 3 after oxymetazoline spray, and 2 after surgery. The SNOT-22 score decreased from 39 at baseline, to 9 at the post-surgery visit. Despite similar symptomatic outcomes, the aerodynamic effect of oxymetazoline was distinctly different and more pronounced than that of surgery. Post-oxymetazoline, nasal resistance was reduced by 56%, while average airflow velocity increased by 128% from baseline. Post-surgery, nasal resistance only reduced by 17%, while average airflow velocity increased by 21%. Peak mucosal heat flux increased 122% post-oxymetazoline versus 27% post-surgery as compared to baseline (Figure 1). Morphologically, oxymetazoline can affect the full length of inferior, middle, and superior turbinates, whereas the effect of surgery is limited to the surgical sites (Figure 2). The high velocity airflow is centered around the inferior portion of the middle turbinate post-oxymetazoline, while distributed towards the inferior turbinate post-surgery (Figure 2). One additional benefit of surgery may be the balancing of airflow between the two nasal cavities. At baseline, the patient's right nasal cavity had 4.55 times higher resistance than the left side. This reduced to 1.35 times after oxymetazoline administration and was nearly even (0.96) after surgery. This airflow-balancing effect may contribute to the marked improvement in airflow sensation post-surgery despite significantly better aerodynamic improvement post-oxymetazoline. This finding necessitates further study to confirm. Oxymetazoline and nasal airway surgery have comparable outcomes in relieving nasal obstructive symptoms. However, they appear to impact nasal morphology and aerodynamics very differently. Additional studies are warranted to rigorously test whether the responsiveness to oxymetazoline is a reliable predictor of satisfactory surgical outcomes. This study was supported by an investigator-initiated research grant by Bayer Health USA, Inc., to K.Z. The authors have no conflicts of interest to report.