Evaluation of airflow characteristics before and after septoplasty in unilateral cleft patients with a deviated nasal septum: a computational fluid dynamics study

An adjoint-based approach for the surgical correction of nasal septal deviations

Deviations of the septal wall are widespread anatomic anomalies of the human nose; they vary significantly in shape and location, and often cause the obstruction of the nasal airways. When severe, septal deviations need to be surgically corrected by ear-nose-throat (ENT) specialists. Septoplasty, however, has a low success rate, owing to the lack of suitable standardized clinical tools for assessing type and severity of obstructions, and for surgery planning. Moreover, the restoration of a perfectly straight septal wall is often impossible and possibly unnecessary. This paper introduces a procedure, based on advanced patient-specific Computational Fluid Dynamics (CFD) simulations, to support ENT surgeons in septoplasty planning. The method hinges upon the theory of adjoint-based optimization, and minimizes a cost function that indirectly accounts for viscous losses. A sensitivity map is computed on the mucosal wall to provide the surgeon with a simple quantification of how much tissue removal at each location would contribute to easing the obstruction. The optimization procedure is applied to three representative nasal anatomies, reconstructed from CT scans of patients affected by complex septal deviations. The computed sensitivity consistently identifies all the anomalies correctly. Virtual surgery, i.e. morphing of the anatomies according to the computed sensitivity, confirms that the characteristics of the nasal airflow improve significantly after small anatomy changes derived from adjoint-based optimization.

Improvement in nasal airway obstruction after secondary rhinoplasty for cleft lip: A systematic review

BACKGROUND

The purpose of the study was to comprehensively review the improvement in nasal airway obstruction after secondary rhinoplasty for cleft lip.

METHODS

The search was conducted on PubMed, Embase, and Scopus databases for relevant studies published within the past twenty years. Inclusion criteria encompassed patients undergoing secondary rhinoplasty with cleft lip nasal deformity and some evaluation of the nasal outcome.

RESULTS

A thorough analysis of available studies identified 29 articles that met the inclusion criteria for final assessment. Seven (24.1%) studies were classified as Therapeutic Ⅱ (T II) according to the American Society of Plastic Surgeons level of evidence scale, while the majority were categorized as T III (17.2%), T IV (51.7%), and T V (6.9%). Subjective methods were employed in 21 articles to measure nasal ventilation outcomes, whereas 8 studies utilized objective methods. Overall findings from all included studies consistently indicated an improvement in nasal ventilation post-surgery.

CONCLUSIONS

Although there is no consensus regarding the impact of secondary rhinoplasty on nasal airway obstruction in cleft lip patients, this review suggests that it can effectively alleviate such obstructions. We conducted an anatomical analysis to investigate the impact of various surgical techniques on nasal ventilation to provide recommendations for postoperative ventilation assessment.

A Longitudinal Study of Improvement in Nasal Airway Obstruction after Secondary Cleft Rhinoplasty

BACKGROUND

Nasal airway obstruction is an increasingly recognized phenomenon in patients with cleft lip and/or palate and has the potential to significantly affect quality of life in this patient population. To date, the effect of secondary cleft rhinoplasty on cleft-related nasal airway obstruction has not been studied.

METHODS

Patients undergoing secondary cleft rhinoplasty at the Children's Hospital of Philadelphia from 2015 to 2021 were identified. Preoperative and postoperative Nasal Obstruction Symptom Evaluation scores were recorded. Alterations in scores were evaluated for variation depending on patient characteristics, operative maneuvers, and postoperative nasal stenting.

RESULTS

Nasal airway obstruction was present in mild to moderate severity in patients before secondary cleft rhinoplasty. Postoperatively, obstruction improved or resolved in the domains of nasal blockage/obstruction, trouble breathing through the nose, and ability to get enough air through the nose during exertion (P < 0.05). Overall composite Nasal Obstruction Symptom Evaluation scores improved (P < 0.05). Lateral crural strut grafting was associated with improvement in nasal blockage, whereas alar revision and tip sutures were associated with worsening in specific nasal symptoms. Patients who underwent nasal stenting were found to report less trouble breathing after surgery than patients who did not (P < 0.05).

CONCLUSIONS

Nasal airway obstruction is present in mild to moderate severity in patients with cleft lip and/or palate, and the subjective severity of obstruction is decreased by secondary cleft rhinoplasty. Specific operative maneuvers are associated with alterations in nasal airway obstructive symptoms, and nasal stenting is associated with an improvement in trouble breathing after secondary cleft rhinoplasty.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Prospective cohort study on short-term evaluation of septoplasty as early management of naso-septal fractures - A correlation of clinical outcomes with computational fluid dynamic parameters

PURPOSE

Post-traumatic deviated nasal septum (PTDNS) leads to impaired breathing and poor esthetics. The aim of this study was to assess treatment outcomes of early septoplasty for correction of PTDNS and correlate it with computational fluid dynamic (CFD) parameters.

METHODS

This prospective cohort study included patients who underwent early septoplasty for PTDNS. Outcome variables were clinical (pain, nasal symmetry, and nasal obstruction) and computational (velocity, pressure, wall shear stress and Reynold's number). The cohort consisted of two groups: patients with history of closed reduction for nasal fractures (CR) and patients without (NCR). The primary outcome measure was response to treatment. Correlation between clinical and computational parameters, and influence of closed reduction on septoplasty outcomes were the secondary and tertiary outcomes, respectively. Descriptive and inferential statistics were performed to analyze data. Level of significance was fixed at 5% (α = 0.05).

RESULTS

The sample included 12 patients, of which 5 underwent CFD analysis. Pain score reduced from a pre-operative mean of 7.3 to 0.5 post-operatively (p<0.001). All patients demonstrated reduction of nasal obstruction (p<0.001) and deviation (p<0.001) post-operatively. CFD analysis revealed post-operative reduction of velocity (p = 0.005) and Reynold's number (p = 0.007), with positive correlation between nasal obstruction and CFD parameters. Though patients in the CR group demonstrated reduced nasal deviation and obstruction before septoplasty, as compared to the NCR group, their outcomes were comparable following septoplasty.

CONCLUSION

Early septoplasty improves functional and esthetic outcomes in patients with PTDNS. CFD simulation is a predictable method to objectively evaluate nasal function.

Inspiration After Posterior Pharyngeal Flap Palatoplasty: A Preliminary Study Using Computational Fluid Dynamic Analysis

Posterior pharyngeal flap palatoplasty (PPF) is one of the most commonly used surgical procedures to correct speech, especially for patients suffering from velopharyngeal insufficiency (VPI). During PPF, surgeons use the catheter to control the lateral velopharyngeal port on each side. Airway obstruction and sleep apnea are common after PPF. To understand the air dynamics of the upper airway after PPF, we used computational fluid dynamics (CFD) to demonstrate the airflow. In our previous study, we have revealed the expiration process of the upper airway after PPF and shown the features of how PPF successfully restores the oral pressure for speech. In this study, we focus on examining the inspiration process. Normal airway structures were included. For the normal velopharyngeal structure, one cylinder was applied to each model. For recapitulating the velopharyngeal structure after PPF, two cylinders were used in each model. The ports for borderline/inadequate closure, which can help the oral cavity get the required pressure, were chosen for this study. A real-time CFD simulation was used to capture the airflow through the ports. We found that the airflow dynamics of the upper airway's inspiration were dependent on the velopharyngeal structure. Although the airflow patterns were similar, the velocities between one-port and two-port structures were different, which explained why patients after PPF breathed harder than before and suggested that the one-port structure might be a better choice for secondary VPI reconstruction based on the CFD analyses.

Rapid Maxillary Expansion Has a Beneficial Effect on the Ventilation in Children With Nasal Septal Deviation: A Computational Fluid Dynamics Study

Nasal septal deviation (NSD) is one of the most common nasal diseases. Different from common clinical examination methods, computational fluid dynamics (CFD) can provide visual flow information of the nasal cavity. The dimension and volume of the nasal cavity are easily affected by rapid maxillary expansion (RME). The purpose of this study was to use CFD to evaluate the effect of RME on the aerodynamics of the nasal cavity in children with maxillary transverse deficiency and NSD. Computational fluid dynamics was implemented after 3D reconstruction based on the CBCT of 15 children who have completed RME treatment. After treatment, the volume increases in the nasal cavity, nasopharynx, oropharynx, and pharynx were not statistically significant. The wall shear stress of the nasal cavity after RME, 1.749 ± 0.673 Pa, was significantly lower than that before RME, 2.684 ± 0.919 Pa. Meanwhile, the maximal negative pressure in the pharyngeal airway during inspiration was smaller after RME (-31.058 Pa) than before (-48.204 Pa). This study suggests that RME has a beneficial effect on nasal ventilation. The nasal airflow became more symmetrical in the bilateral nasal cavity after RME. Pharyngeal resistance decreased with the reduction in nasal resistance and the increase in the volume of oropharynx after RME.