Nasal saline irrigation - A review of current anatomical, clinical and computational modelling approaches

Exploring E-Vape Aerosol Penetration into Paranasal Sinuses: Insights from Patient-Specific Models

Background: Acute and chronic sinusitis significantly impact patients' quality of life. Effective drug delivery to paranasal sinuses is crucial for treating these conditions. However, medications from conventional devices like nasal drops, sprays, and nebulized mists often fail to penetrate the small ostia and reach the sinuses. This study aims to assess the effectiveness of e-vape-generated aerosols entering and filling paranasal sinus cavities, particularly the maxillary sinus. Methods: The aerosol droplets were generated using an electronic vaporizer (e-vape) and were composed solely of vegetable glycerin (VG) and propylene glycol (PG). Patient-specific, transparent nose-sinus models, including one with post-uncinectomy surgery, were used to evaluate the effectiveness of these e-vape-generated VG-PG aerosols in entering the sinuses under unidirectional and bidirectional airflow conditions. Visualizations from various nasal model views and lighting conditions were recorded. Particle size distribution measurements of the e-vape aerosol were conducted using a laser diffraction particle size analyzer. Results: E-vape-generated VG-PG droplets effectively enter paranasal sinuses under specific administration conditions. E-vape aerosol droplet size measurements revealed a mean particle size ranging from 2.895 to 3.359 μm, with a median particle size (D50) averaging 2.963 μm. The speed of aerosol entering the paranasal sinuses is directly proportional to the ostia size; larger ostia result in faster sinus entry. A continuous moderate flow is necessary to gradually fill the paranasal sinus cavities. The aerosol entry into sinuses was observed at 2 L/min and decreased with increasing flow rate. The mechanisms of aerosol entry involve maintaining a positive pressure gradient across the ostial canal, a non-equilibrium transverse pressure distribution, and a two-way flow through the ostium. Gravitational forces and recirculation currents further enhance the deposition of e-vape aerosols. Comparative tests showed that traditional delivery devices exhibited limited penetration into paranasal sinuses. Conclusions: This study demonstrated that e-vape-generated aerosols could serve as a vehicle for delivering active pharmaceutical ingredients (APIs) directly to the paranasal sinuses, improving treatment outcomes.

Optimized gravity-driven intranasal drop administration delivers significant doses to the ostiomeatal complex and maxillary sinus

Chronic and allergic rhinosinusitis impacts approximately 12% of the global population. Challenges in rhinosinusitis treatment include paranasal sinus inaccessibility and variability in delivery efficiency among individuals. This study addresses these challenges of drug delivery by developing a high-efficiency, low-variability protocol for nasal drop delivery to the ostiomeatal complex (OMC) and maxillary sinus. Patient-specific nasal casts were dissected to reveal the configurations of conchae and meatus, providing insights into anatomical features amendable for sinus delivery. Fluorescent dye-enhanced videos visualized the dynamic liquid translocation in transparent nasal casts, allowing real-time assessment and quick adjustment to delivery parameters. Dosimetry to the OMC and maxillary sinus were quantified as drop count and mass using a precision scale. Key delivery factors, including the device type, formulation, and head-chin orientation, were systematically investigated in a cohort of ten nasal casts. Results show that both the squeeze bottle and soft-mist nasal pump yielded notably low doses to the OMC with high variability, and no dose from these two devices was detected within the maxillary sinuses. In contrast, the proposed approach, which included a curved nozzle surpassing the nasal valve and leveraged gravity-driven liquid translocation along the lateral nasal wall, delivered significant doses to the OMC and maxillary sinus. Iterative experimentations identified the optimal head tilt to be 40° and chin tilt to be° from the lateral recumbent position. Statistical analyses established the drop count required for effective OMC/sinus delivery. The proposed delivery protocol holds the potential to enhance chronic rhinosinusitis treatment outcomes with low variability. The dual role of nasal anatomy in posing challenges and offering opportunities highlights the need for future investigations using diverse formulations in a larger cohort of nasal models.

A large-volume low-pressure nasal irrigation delivers drug into the nasal cavity? An in vivo study

The nasal administration route emerged as an interesting route in systemic and brain drug delivery, and different modalities of nasal delivery are available. The nasal irrigation is one of them, but there is a lack of studies investigating the distribution of a large-volume irrigation. The main aim of this study was to assess the deposition of radiolabeled saline in the nasal cavities and paranasal sinuses following nasal irrigation by imaging. Five healthy males volunteered to perform large-volume low-pressure nasal irrigation, with a douching device containing 50 mL of radiolabeled isotonic saline. Participants underwent a scintigraphy immediately after. Both the nasal cavities and maxillary sinuses were systematically reached by the solution during nasal irrigation. The sinuses set in a lower position during nasal irrigation showed a tendency to be more irrigated than the sinuses set in a higher position (7.67% vs 22.72%; p = 0.086). Moreover, substantial inter- and intraindividual heterogeneity regarding solution deposition was observed. Large-volume low-pressure nasal irrigation is a good modality to reach the maxillary sinuses as well as the nasal cavities. In order to ensure adequate reaching of both nasal cavities and paranasal sinuses, nasal irrigation should be performed bilaterally.

Assessing Nasal Epithelial Dynamics: Impact of the Natural Nasal Cycle on Intranasal Spray Deposition

This study investigated the intricate dynamics of intranasal spray deposition within nasal models, considering variations in head orientation and stages of the nasal cycle. Employing controlled delivery conditions, we compared the deposition patterns of saline nasal sprays in models representing congestion (N1), normal (N0), and decongestion (P1, P2) during one nasal cycle. The results highlighted the impact of the nasal cycle on spray distribution, with congestion leading to confined deposition and decongestion allowing for broader dispersion of spray droplets and increased sedimentation towards the posterior turbinate. In particular, the progressive nasal dilation from N1 to P2 decreased the spray deposition in the middle turbinate. The head angle, in conjunction with the nasal cycle, significantly influenced the nasal spray deposition distribution, affecting targeted drug delivery within the nasal cavity. Despite controlled parameters, a notable variance in deposition was observed, emphasizing the complex interplay of gravity, flow shear, nasal cycle, and nasal morphology. The magnitude of variance increased as the head tilt angle increased backward from upright to 22.5° to 45° due to increasing gravity and liquid film destabilization, especially under decongestion conditions (P1, P2). This study's findings underscore the importance of considering both natural physiological variations and head orientation in optimizing intranasal drug delivery.

Nasal Irrigation Delivery in Three Post-FESS Models From a Squeeze-bottle Using CFD

Purpose

Nasal saline irrigation is highly recommended in patients following functional endoscopic sinus surgery (FESS) to aid the postoperative recovery. Post-FESS patients have significantly altered anatomy leading to markedly different flow dynamics from those found in pre-op or non-diseased airways, resulting in unknown flow dynamics.

Methods

This work investigated how the liquid stream disperses through altered nasal cavities following surgery using Computational Fluid Dynamics (CFD). A realistic squeeze profile was determined from physical experiments with a 27-year-old male using a squeeze bottle with load sensors. The administration technique involved a head tilt of 45-degrees forward to represent a head position over a sink. After the irrigation event that lasted 4.5 s, the simulation continued for an additional 1.5 s, with the head orientation returning to an upright position.

Results

The results demonstrated that a large maxillary sinus ostium on the right side allows saline penetration into this sinus. The increased volume of saline entering the maxillary sinus limits the saline volume available to the rest of the sinonasal cavity and reduces the surface coverage of the other paranasal sinuses. The average wall shear stress was higher on the right side than on the other side for two patients. The results also revealed that head position alters the sinuses’ saline residual, especially the frontal sinuses.

Conclusion

While greater access to sinuses is achieved through FESS surgery, patients without a nasal septum limits posterior sinus penetration due to the liquid crossing over to the contralateral cavity and exiting the nasal cavity early.

Nasal irrigation practice habits in infants: A Belgian survey: Nasal irrigation practice habits in infants

BACKGROUND

Nasal irrigation is widely used in infants to relieve nasal obstruction. However, the nasal irrigation technique has not been standardized, and nasal irrigation practice habits (NIPH) in infants have not been investigated. Our objective was to provide an overview of NIPH in infants among parents, childcare workers, and healthcare professionals living in Belgium.

METHODS

Parents, childcare workers, physiotherapists, nurses, pharmacists, and physicians were invited to fill in an electronic survey questioning their NIPH in infants. The survey was disseminated through social networks, practitioners' associations, and creches.

RESULTS

The questionnaire was fully completed by 359 participants. A ready-made solution was used by 93% of participants, of whom 92% used physiological saline. The prophylactic use of nasal irrigation was considered appropriate or very appropriate by 65% of all participants. The irrigation frequency was particularly heterogeneous among participants. The optimal solution propulsion speed and solution volume to be used depended on the group of participants being interviewed. At least 37% of parents and 20% of physicians did not take a stand on the optimal irrigation volume to use in each age category. On average, 83% of participants described performing nasal irrigation by lying the infant on one side and delivering the solution through the top nostril. Finally, 74% of respondents declared that no risk was associated with this technique.

CONCLUSION

Although some common NIPH viewpoints among the surveyed participants were identified, several disagreements were reported, reflecting the absence of a standardized method of nasal irrigation.

Development of an apparatus and procedure for evaluating the efficiency of nasal irrigation

BACKGROUND

Although different methods of nasal irrigation have been utilized, irrigation efficiency in nasal cavities has not been well assessed. The objective of this study was to develop an apparatus and procedure for evaluating the irrigation efficiency and to explore the optimal head position during irrigation.

METHODS

Casts of the left sinonasal cavity from a healthy volunteer were made from high-resolution-computed tomography data using 3D printing with composite materials. An adjustable apparatus that allowed cast fixation at the different head positions was built. The yogurt was used to simulate mucus. The cast with 5 ml yogurt filled around the superior, middle, and inferior turbinate was fixed in six head positions including head tilt 10°, 45°, and 60° forward with or without leaning 30° to the right. The cast was irrigated with 120 ml, 175 ml, and 240 ml dyed water and was video recorded. The irrigation efficiency was calculated based on the weight difference of the cast before and after the irrigation.

RESULTS

Most residual yogurt was located around the superior meatus after the irrigation under different volumes and head positions. The irrigation efficiency of the rinse bottle or the pulsatile device was volume dependent, with the highest irrigation efficiency under 240 ml water. When the left sinonasal cavity was irrigated, the head position of tilt 45° forward with leaning 30° to the right was the optimal head position for these two devices when compared to other positions. The pulsatile device with 240 ml water performed better than the rinse bottle with 240 ml water regarding the irrigation efficiency under the optimal head position (0.8700 ± 0.0138 vs 0.7536 ± 0.0099, p = 0.003).

CONCLUSIONS

The developed apparatus provided a potential method for evaluating the irrigation efficiency. The head position of tilt 45° forward with leaning 30° was suitable for patients to perform the nasal irrigation.

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.