Perception of better nasal patency correlates with increased mucosal cooling after surgery for nasal obstruction

Abstract

Objectives: To (1) quantify mucosal cooling (ie, heat loss) spatially in the nasal passages of nasal airway obstruction (NAO) patients before and after surgery using computational fluid dynamics (CFD) and (2) correlate mucosal cooling with patient-reported symptoms, as measured by the Nasal Obstruction Symptom Evaluation (NOSE) and a visual analog scale (VAS) for sensation of nasal airflow.

Study design: Prospective.

Setting: Academic tertiary medical center.

Subjects and methods: Computed tomography (CT) scans and NOSE and VAS surveys were obtained from 10 patients before and after surgery to relieve NAO. Three-dimensional models of each patient's nasal anatomy were used to run steady-state CFD simulations of airflow and heat transfer during inspiration. Heat loss across the nasal vestibule and the entire nasal cavity, as well as the surface area of mucosa exposed to heat fluxes >50 W/m(2), were compared pre- and postoperatively.

Results: After surgery, heat loss increased significantly on the preoperative most obstructed side (P < .0002). A larger surface area of nasal mucosa was exposed to heat fluxes >50 W/m(2) after surgery. The best correlation between patient-reported and CFD measures of nasal patency was obtained for NOSE against surface area in which heat fluxes were >50 W/m(2) (Pearson r = -0.76).

Conclusion: A significant postoperative increase in mucosal cooling correlates well with patients' perception of better nasal patency after NAO surgery. Computational fluid dynamics-derived heat fluxes may prove to be a valuable predictor of success in NAO surgery.

Keywords: NOSE scale; computational fluid dynamics (CFD); heat flux; mucosal cooling; nasal obstruction; nasal surgery; septoplasty; turbinate reduction; visual analog scale (VAS).

Figure 1

(Top) Pre- and post-surgery CT scans and computational models of the nasal anatomy of a patient with nasal obstruction. Dark gray: nasopharynx. Light gray: nasal cavity. Middle-tone gray: nasal vestibule. (Bottom) Cross-sections by distance from nostris. Abbreviations: S = septum; IT = inferior turbinate; # = septoplasty; * = turbinate reduction.

Figure 2

Spatial distribution of heat fluxes on nasal septum of a patient with nasal obstruction. Post-surgical increases in heat fluxes are noticeable on the right cavity, which was the most obstructed side pre-operatively.

Figure 3

Average heat fluxes, which are higher in the vestibule than in the nasal cavity, increased post-operatively in the most obstructed side. Asterisks denote statistically significant differences (p-value < 0.0002, n = 10 individuals). Highlighted as dashed line is the patient depicted in Figures 1 and 2.

Figure 4

Heat flux averaged along the perimeter of coronal sections and plotted as a function of distance from nostrils. Asterisks (*) denote statistically higher heat fluxes post-surgery (p-value < 0.05, n = 10 individuals).

Figure 5

Surface area stimulated by different levels of heat flux in the nasal cavity (left) and vestibule (right) on the side most obstructed pre-operatively. Asterisks (*) denote statistically higher area post-surgery (p-value < 0.05, n = 10 individuals).

Figure 6

(TOP) Correlation between subjective measures of nasal patency (NOSE and VAS scores) and the surface area stimulated by heat fluxes (HF) > 50 W/m² in the most obstructed nasal cavity. (BOTTOM) The Pearson correlation coefficients for area stimulated vs. NOSE (r_NOSE) and VAS (r_VAS) are dependent on the heat flux stimulation threshold. The best correlations were obtained for threshold = 50 W/m².