A computational fluid dynamics analysis of the effects of size and shape of anterior nasal septal perforations.

BACKGROUND: Nasal septal perforations (NSPs) often cause bleeding, crusting, obstruction, and/or whistling. The objective was to analyze the impact of anterior NSP size and shape on nasal physiology using computational fluid dynamics (CFD). METHODS: A 3-dimensional model of the nasal cavity was constructed from a radiologically normal CT scan using imaging software. Anterior NSPs (ovoid (ONSP): 0.5, 1, 2, and 3 cm long anterior-to-posteriorly and round (RNSP, 0.5 and 1 cm)) were virtually created in the model and divided into ventral, dorsal, anterior, and posterior regions. Steady-state inspiratory airflow, heat, and water vapor transport were simulated using Fluent CFD software. Air crossover through the perforation, wall shear, heat flux, water vapor flux, resistance, and humidification were analyzed. RESULTS: Air crossover and wall shear increased with perforation size. Regionally, wall shear and heat and water vapor flux were highest posteriorly and lowest anteriorly, generally increasing with size in those regions. RNSPs had greater heat and water vapor flux compared to corresponding size ONSPs. Resistance decreased by 10% or more from normal only in the 3 cm ONSP. Maximum water content was achieved more posteriorly in larger NSP nasal cavities. CONCLUSIONS: High wall shear and heat and water vapor flux in posterior perforation regions may explain the crusting most commonly noted on posterior NSP edges. This preliminary study suggests that larger NSPs have a greater effect on nasal resistance and water content. Decrease in resistance with larger NSP size may be implicated in reported symptomatic improvement following enlargement of NSPs for treatment.

Self-reported anxiety and depression unchanged after endoscopic sinus surgery for chronic rhinosinusitis.

BACKGROUND: Prior research has established that anxiety and depression, as measured by the Hospital Anxiety Depression Score (HADS), are strongly correlated with disease-specific quality of life (Rhinosinusitis Disability Index - RSDI) in chronic rhinosinusitis (CRS). We hypothesized that anxiety and depression would decrease after functional endoscopic sinus surgery (FESS), and furthermore that HADS would predict improvement in RSDI following surgery. METHODOLOGY: The study cohort from 2014 consisted of 99 CRS patients who underwent nasal endoscopy, RSDI, and HADS evaluation. The cohort was segregated by whether or not they underwent FESS and an updated HADS was administered. For 44 surgical patients, pre- and post-operative RSDI (n=38), Lund-Kennedy (LK) (n=34) and HADS (n=18) scores were compared. Delta RSDI was compared between patients with varying levels of anxiety and depression. RESULTS: Lund-Kennedy scores improved from 5.8 ± 4.1 to 3.2 ± 2.6 following surgery, as did total RSDI (39.3 ± 26.8 to 24.6 ± 29.2). Total HADS (9.8 ± 6.4 to 11.3 ± 7.4) and depression and anxiety subscores were unchanged. Linear regression did not reveal a correlation between HADS and change in RSDI following FESS. Delta RSDI was not significantly different between patients with varying levels of anxiety and depression. CONCLUSIONS: Despite improvements in objective evidence of sinonasal inflammation (LK) and disease-specific quality of life (RSDI), neither depression nor anxiety improved after FESS, nor did the magnitude of psychological comorbidity predict post-operative improvement in quality of life. Improvement in RSDI was not different among patients with varying levels of anxiety and depression. Levels of depression and anxiety may be hard-wired, and therefore not influenced by changes in objective or perceived sinonasal disease burden.

A computational study of functional endoscopic sinus surgery and maxillary sinus drug delivery.

BACKGROUND: Topical medication is increasingly used following functional endoscopic sinus surgery (FESS). Information on particle sizes that maximise maxillary sinus (MS) delivery is conflicting, and the effect of antrostomy size on delivery is unclear. The purpose of this study was to estimate antrostomy and particle size effects on topical MS drug delivery. METHODOLOGY: Sinonasal reconstructions were created from a pre- and a post-FESS CT scan in each of four chronic rhinosinusitis patients. Additional models were created from each post-FESS reconstruction representing four alternative antrostomy sizes. Airflow and particle deposition were simulated in each reconstruction using computational fluid dynamics for nebulised and sprayed delivery. RESULTS: MS ventilation and drug delivery increased following FESS, the largest virtual antrostomy led to greatest delivery, and MS delivery was sensitive to particle size. Particles within a 5-18 µm and 5-20 µm size range led to peak MS deposition for nebulised and sprayed particles, respectively. Post-FESS increases in drug delivery varied across individuals and within individuals by the type of antrostomy created. CONCLUSION: Our findings suggest that FESS, particularly with larger antrostomies, improves topical drug delivery, and that certain particle sizes improve this delivery. Further research is needed to contextualise these findings with other post-surgical effects.