Nasal Airflow Changes With Bioabsorbable Implant, Butterfly, and Spreader Grafts

Cadaveric Assessment of the Butterfly Graft in Rhinoplasty

INTRODUCTION

The rhinoplasty butterfly graft is used to improve the internal nasal valve (INV), but post-operative visibility remains a concern. Intraoperative techniques have developed to thin the graft with unknown effect on functionality.

OBJECTIVES

Improve understanding of how to modify the aesthetics of the butterfly graft without impacting patient outcomes. Determine how graft contouring affects its biomechanical properties.

METHODS

Cadaveric cartilage grafts were used to examine the biomechanics in its native state and with progressive thinning. The force needed to stabilize the INV in an unaltered state and the resistance force provided by native (original), partially thinned, and fully thinned cartilage grafts were recorded.

RESULTS

The mean thickness of grafts in their natural state was 1.64 mm, median 1.50 mm (SD 0.64 mm). The fully-thinned mean was 0.84 mm, median 0.8 mm (SD 0.18 mm). The mean force (N) of the native graft was 0.74 N and 0.60 N for fully thin (p = 0.016, 95%). The mean force (N) needed to stabilize the INV was 0.15 N (right) and 0.19 N (left).

CONCLUSION

Butterfly grafts can be thinned by approximately 50% of their original thickness and retain the strength to stabilize the INV.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:1638-1641, 2024.

Olfactory drug delivery with intranasal sprays after nasal midvault reconstruction

Conductive olfaction and nose to brain drug delivery are important processes that remain limited by inadequate odorant or drug delivery to the olfactory airspace. Primary challenges include anatomic barriers and poor targeting to the olfactory region. This study uses computational fluid dynamics to investigate the effects of nasal midvault surgery on olfactory drug delivery with intranasal sprays. Soft tissue elevation, spreader flaps, and spreader grafts were performed on two fresh cadaveric specimens, using computed tomography for airway reconstruction. Nasal airflow and drug particle transport simulations were performed under these conditions: inhalation rate (15, 30 L/min), spray velocity (1, 5, 10 m/s), spray location (top, bottom, center, medial, lateral), head position (upright, supine, forward, backward), and particle size (1-100 µm). Simulation results were used to calculate drug particle deposition to the olfactory airspaces and bulbs. Total olfactory deposition was < 5% but attained a maximum of 36.33% when sorted by particle size. There was no association between nasal midvault surgery and olfactory deposition. No single parameter or technique demonstrated superior olfactory deposition, but smaller particle size, slower spray velocity, and higher inhalation rate tended to optimize olfactory deposition, providing important implications for future intranasal spray and drug design to target the olfactory airspace.

Functional nasal surgery in the office-based setting

Objective

Nasal obstruction is a very common problem often addressed by functional nasal surgery. Increasingly, these procedures are being performed in the office setting secondary to decreased down time, cost, and obviation of general anesthesia. Our goal with this review is to discuss how to appropriately select patients for office-based procedures, what procedures may be considered, and current outcomes with in-office functional nasal surgery.

Data Sources

PubMed, Scopus, Google Scholar.

Methods

Research databases were searched for articles discussing techniques for performing functional nasal surgery in an office setting, and outcomes of various in-office functional nasal procedures.

Results

Studies found and included in this review discuss many aspects of office-based functional nasal surgery, including practical points on patient selection and office set-up, what procedures can safely be performed, and outcomes of different techniques to address specific problems. Broadly, procedures amenable to performance in the office address the internal and external nasal valves, the nasal septum, and the inferior turbinates.

Conclusion

A wide range of techniques to aaddress the nasal valves, septum, and inferior turbinates can be performed in a safe and effective manner without the need for an operative suite.

No magic bullet: Limiting in-school transmission in the face of variable SARS-CoV-2 viral loads

In the face of a long-running pandemic, understanding the drivers of ongoing SARS-CoV-2 transmission is crucial for the rational management of COVID-19 disease burden. Keeping schools open has emerged as a vital societal imperative during the pandemic, but in-school transmission of SARS-CoV-2 can contribute to further prolonging the pandemic. In this context, the role of schools in driving SARS-CoV-2 transmission acquires critical importance. Here we model in-school transmission from first principles to investigate the effectiveness of layered mitigation strategies on limiting in-school spread. We examined the effect of masks and air quality (ventilation, filtration and ionizers) on steady-state viral load in classrooms, as well as on the number of particles inhaled by an uninfected person. The effectiveness of these measures in limiting viral transmission was assessed for variants with different levels of mean viral load (ancestral, Delta, Omicron). Our results suggest that a layered mitigation strategy can be used effectively to limit in-school transmission, with certain limitations. First, poorly designed strategies (insufficient ventilation, no masks, staying open under high levels of community transmission) will permit in-school spread even if some level of mitigation is present. Second, for viral variants that are sufficiently contagious, it may be difficult to construct any set of interventions capable of blocking transmission once an infected individual is present, underscoring the importance of other measures. Our findings provide practical recommendations; in particular, the use of a layered mitigation strategy that is designed to limit transmission, with other measures such as frequent surveillance testing and smaller class sizes (such as by offering remote schooling options to those who prefer it) as needed.

Anatomic Optical Coherence Tomography (aOCT) for Evaluation of the Internal Nasal Valve

OBJECTIVES/HYPOTHESIS

To establish the utility of anatomic optical coherence tomography (aOCT) in evaluating internal nasal valve (INV).

STUDY DESIGN

Anatomic specimen imaging study.

METHODS

Fresh-harvested human specimen heads were evaluated using both computed tomography (CT) imaging as well as using aOCT. Scans were performed at three time points: 1) After septoplasty for cartilage harvest, 2) after placement of butterfly graft (BFG), and 3) after placement of bilateral spreader grafts (SG). Imaging data were then converted into 3D models of the nasal airway. CT- and aOCT-generated models were compared by both static volumetric analysis and computational fluid dynamics (CFD) to predict nasal resistance and pressure.

RESULTS

Scans using aOCT showed comparable results to CT in terms of volumetric parameters both before and after intervention. Analysis of aOCT data by CFD demonstrated decrease in pressure after SG or BFG intervention. No statistically significant difference was observed when comparing CT- and aOCT-generated calculations of pressure or resistance.

CONCLUSION

The INV can be imaged in a static fashion using aOCT technology. Advantages over traditional CT imaging include lack of exposure to radiation and rapid scan time. In addition, in-office use is possible as aOCT technology develops. Further investigation will be necessary to define the role of aOCT in the dynamic evaluation of this vital component of the nasal airway.

LEVEL OF EVIDENCE

3 Laryngoscope, 132:2148-2156, 2022.

Spreader Graft vs Spreader Flap in Rhinoplasty: A Systematic Review and Meta-Analysis of Aesthetic and Functional Outcomes

BACKGROUND

Insufficient support of the nasal mid-vault during rhinoplasty can cause significant complications. Accordingly, surgeons have recently paid much more attention to the preservation of nasal patency. The spreader graft is the gold standard technique for the reconstruction of nasal mid-vault.

OBJECTIVES

The objective of this study was to compare the spreader graft and spreader flap in terms of aesthetic and functional outcomes.

METHODS

An inclusive search was performed with PubMed/Medline, Google Scholar, and Cochrane Library databases up to April 2021. Multiple aesthetic and functional factors, including dorsal aesthetic lines restoration, satisfaction rate, internal nasal valve angle improvement, nasal obstruction symptom evaluation scale, and active anterior rhinomanometry were evaluated. Also, a meta-analysis was performed on the included articles that provided adequate data for mentioned factors.

RESULTS

After excluding papers that did not conform with the selection criteria, 10 articles with a total sample size of 567 cases with a mean age of 27.7 years (range, 18-65 years) were finally included. Analysis of the data revealed no statistically significant difference between the spreader graft and spreader flap techniques in terms of dorsal aesthetic lines restoration, internal nasal valve angle improvement, nasal obstruction symptom evaluation scale, and anterior rhinomanometry.

CONCLUSIONS

However, in terms of satisfaction rate, the analyzes indicated that spreader graft has significantly superior aesthetic outcomes. Generally, in case of appropriately selected patients, there is no statistically significant difference between spreader graft and spreader flap techniques in terms of aesthetic and functional outcomes.

LEVEL OF EVIDENCE: 4

Computational characterization of inhaled droplet transport to the nasopharynx

How human respiratory physiology and the transport phenomena associated with inhaled airflow in the upper airway proceed to impact transmission of SARS-CoV-2, leading to the initial infection, stays an open question. An answer can help determine the susceptibility of an individual on exposure to a COVID-2019 carrier and can also provide a preliminary projection of the still-unknown infectious dose for the disease. Computational fluid mechanics enabled tracking of respiratory transport in medical imaging-based anatomic domains shows that the regional deposition of virus-laden inhaled droplets at the initial nasopharyngeal infection site peaks for the droplet size range of approximately 2.5-19 [Formula: see text]. Through integrating the numerical findings on inhaled transmission with sputum assessment data from hospitalized COVID-19 patients and earlier measurements of ejecta size distribution generated during regular speech, this study further reveals that the number of virions that may go on to establish the SARS-CoV-2 infection in a subject could merely be in the order of hundreds.

Can computational fluid dynamic models help us in the treatment of chronic rhinosinusitis

PURPOSE OF REVIEW

The aim of this study was to review the recent literature (January 2017-July 2020) on computational fluid dynamics (CFD) studies relating to chronic rhinosinusitis (CRS), including airflow within the pre and postoperative sinonasal cavity, virtual surgery, topical drug and saline delivery (sprays, nebulizers and rinses) and olfaction.

RECENT FINDINGS

Novel CFD-specific parameters (heat flux and wall shear stress) are highly correlated with patient perception of nasal patency. Increased ostial size markedly improves sinus ventilation and drug delivery. New virtual surgery tools allow surgeons to optimize interventions. Sinus deposition of nasal sprays is more effective with smaller, low-inertia particles, outside of the range produced by many commercially available products. Saline irrigation effectiveness is improved using greater volume, with liquid entering sinuses via 'flooding' of ostia rather than direct jet entry.

SUMMARY

CFD has provided new insights into sinonasal airflow, air-conditioning function, the nasal cycle, novel measures of nasal patency and the impact of polyps and sinus surgery on olfaction. The deposition efficiency of topical medications on sinus mucosa can be markedly improved through parametric CFD experiments by optimising nasal spray particle size and velocity, nozzle angle and insertion location, while saline irrigation effectiveness can be optimized by modelling squeeze bottle volume and head position. More sophisticated CFD models (inhalation and exhalation, spray particle and saline irrigation) will increasingly provide translational benefits in the clinical management of CRS.

Numerical evaluation of spray position for improved nasal drug delivery

Topical intra-nasal sprays are amongst the most commonly prescribed therapeutic options for sinonasal diseases in humans. However, inconsistency and ambiguity in instructions show a lack of definitive knowledge on best spray use techniques. In this study, we have identified a new usage strategy for nasal sprays available over-the-counter, that registers an average 8-fold improvement in topical delivery of drugs at diseased sites, when compared to prevalent spray techniques. The protocol involves re-orienting the spray axis to harness inertial motion of particulates and has been developed using computational fluid dynamics simulations of respiratory airflow and droplet transport in medical imaging-based digital models. Simulated dose in representative models is validated through in vitro spray measurements in 3D-printed anatomic replicas using the gamma scintigraphy technique. This work breaks new ground in proposing an alternative user-friendly strategy that can significantly enhance topical delivery inside human nose. While these findings can eventually translate into personalized spray usage instructions and hence merit a change in nasal standard-of-care, this study also demonstrates how relatively simple engineering analysis tools can revolutionize everyday healthcare. Finally, with respiratory mucosa as the initial coronavirus infection site, our findings are relevant to intra-nasal vaccines that are in-development, to mitigate the COVID-19 pandemic.