Influence of pharyngeal airway respiration pressure on Class <scp>II</scp> mandibular retrusion in children: A computational fluid dynamics study of inspiration and expiration

Iwasaki, Tomonori; Sato, Hideo; Suga, Hokuto; Takemoto, Yoshihiko; Inada, Emi; Saitoh, Issei; Kakuno, K.; Kanomi, Ryuzo; Yamasaki, Yuichi

doi:10.1111/ocr.12145

Cited by 12 publications

(8 citation statements)

References 19 publications

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“…They reported that when negative pressure was greater than −50 Pa, OSA symptoms were detected. Based on these reports and our results, we suggest that obstruction might occur if the negative pressure of the PA is greater than −50 Pa. A large negative pressure in the PA on inspiration, coupled with muscle relaxation, may present with a higher risk of PA collapse during sleep.…”

Section: Discussionsupporting

confidence: 68%

Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

Shirazawa

Iwasaki

Ooi

et al. 2020

Orthod Craniofacial Res

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Objectives: This study aimed to determine the anteroposterior depth (APD) of the pharyngeal airway (PA) where post-operative PA obstruction was predicted, using computer fluid dynamics (CFD), in order to prevent obstructive sleep apnoea after mandibular setback surgery. Settings and sample population: Nineteen skeletal Class III patients (8 men; mean age, 26.7 years) who required mandibular setback surgery had computed tomography images taken before and 6 months after surgery. Methods: The APD of each site of the four cross-sectional reference planes (retropalatal airway [RA], second cervical vertebral airway, oropharyngeal airway and third cervical vertebral airway) were measured. The Maximum negative pressure (Pmax) of the PA was measured at inspiration using CFD, based on a three-dimensional PA model. Intersite differences were determined using analysis of variance and the Friedman test with Bonferroni correction. The relationship between APD and Pmax was evaluated by Spearman correlation coefficients and non-linear regression analysis. Results: The smallest PA site was the RA. Pmax was significantly correlated with the APD of the RA (r s = .628, P < .001). The relationship between Pmax and the APD-RA was fitted to a curve, which showed an inversely proportional relationship of Pmax to the square of the APD-RA. Pmax substantially increased even with a slight reduction of the APD-RA. In particular, when the APD-RA was 7 mm or less, Pmax increased greatly, suggesting that PA obstruction was more likely to occur. Conclusions: The results of this study suggest that APD-RA is a useful predictor of good PA ventilation after surgery. K E Y W O R D S computational fluid dynamics, mandibular setback surgery, obstructive sleep apnoea, pharyngeal airway depth, skeletal class III How to cite this article: Shirazawa Y, Iwasaki T, Ooi K, et al. Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study.

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Section: Discussionsupporting

confidence: 68%

Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

Shirazawa

Iwasaki

Ooi

et al. 2020

Orthod Craniofacial Res

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“…CFD was used to simulate ventilation of the PA models as follows (Fig. ) . The models were exported to fluid dynamics software (Phoenics; CHAM‐Japan, Tokyo, Japan) in stereolithographic format, and the fluid was assumed to be Newtonian, homogeneous, and incompressible.…”

Section: Methodsmentioning

confidence: 99%

“…1). 13,14 The models were exported to fluid dynamics software (Phoenics; CHAM-Japan, Tokyo, Japan) in stereolithographic format, and the fluid was assumed to be Newtonian, homogeneous, and incompressible. Elliptic-staggered equations and a continuity equation were used in the analysis.…”

Section: Simulation Of Pharyngeal Airway Ventilation Conditionsmentioning

confidence: 99%

Evaluation of the pharyngeal airway using computational fluid dynamics in patients with acromegaly

Mukaihara

Hasegawa-Moriyama

Iwasaki

et al. 2018

Laryngoscope Investig Oto

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ObjectivesPerioperative airway management may be particularly challenging in patients with acromegaly undergoing trans‐sphenoidal pituitary surgery (TSS). Management for airway obstruction is required prior to pituitary surgery to minimize perioperative hypoxia. The purpose of this retrospective study was to evaluate airway obstruction by simulation of computational fluid dynamics (CFD) using computed tomography (CT) images in patients who had undergone TSS.MethodsCT images of the nasopharyngeal airways of patients with acromegaly (n = 5) or nonfunctional pituitary adenoma (n = 6) undergoing TSS from April 2012 to January 2017 were used to construct these airways in three dimensions. Estimated airflow pressure and velocity in the retropalatal airway (RA), oropharyngeal airway (OA), and hypopharyngeal airway (HA) were simulated using CFD.ResultsEstimated pharyngeal airflow pressure in the HA, OA, and RA was significantly greater in patients with acromegaly than in those with nonfunctional pituitary adenomas whereas the estimated pharyngeal airflow velocity was significantly impaired only in the RA of patients with acromegaly. Minimum postoperative SpO2 both within 3 hours and from 3 to 12 hours after the end of anesthesia was significantly lower in the patients with acromegaly. Additionally, estimated volume of tongue and pharyngeal airflow pressure in the HA, OA, and RA correlated with minimum postoperative SpO2.ConclusionPharyngeal airflow pressure estimated from CT images is high in patients with acromegaly, and these values correlate with postoperative minimum values for SpO2. Preoperative evaluation of CT images by CFD can predict difficulty in airway management and perioperative hypoxia.Level of Evidence4.

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“…Several articles demonstrated clinically that patients with high nasal resistance have negative nasopharyngeal pressures. 22,23 Tomblinson et al 24 suggested that inferior turbinate hypertrophy is directly correlated with degree of septal deviation, although the cause-and-effect relationship between septum and turbinates remains unclear. Another study found that both turbinate size and degree of sinusitis were associated with a narrower nasal cavity, suggesting that the negative pressure of the narrow valve could be responsible for the sinus mucosal disease.…”

Section: Discussionmentioning

confidence: 99%

Effect of Nasal Valve Shape on Downstream Volume, Airflow, and Pressure Drop: Importance of the Nasal Valve Revisited

Naughton

Lee

Ramos

et al. 2018

Ann Otol Rhinol Laryngol

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Influence of pharyngeal airway respiration pressure on Class II mandibular retrusion in children: A computational fluid dynamics study of inspiration and expiration

Abstract: Large negative inspiratory pharyngeal airway pressure due to nasal obstruction in children with Class II malocclusion may be related to their retrognathia.

Cited by 12 publications

References 19 publications

Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

Relationship between pharyngeal airway depth and ventilation condition in mandibular setback surgery: A computational fluid dynamics study

Evaluation of the pharyngeal airway using computational fluid dynamics in patients with acromegaly

Effect of Nasal Valve Shape on Downstream Volume, Airflow, and Pressure Drop: Importance of the Nasal Valve Revisited

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