The effect of geniglossal advancement on airway flow using a computational flow dynamics model

Coblation Versus Radiofrequency for Tongue Base Reduction in Obstructive Sleep Apnea: A Meta-analysis

Objective

The objective of this study is to determine the effectiveness and safety profile of coblation tongue base reduction (CBTR) compared to radiofrequency base of tongue (RFBOT) reduction on sleep-related outcomes in patients with obstructive sleep apnea (OSA).

Data Sources

PubMed, Scopus, Web of Science, and Cochrane Database of Systematic Reviews databases.

Review Methods

Literature search by 2 independent authors was conducted using the abovementioned databases. Studies on CBTR and RFBOT as part of OSA treatment in adult patients with pre- and postoperative apnea-hypopnea index (AHI) were included. Direct meta-analysis and single-arm meta-analysis were conducted to compare sleep-related outcomes (AHI, apnea index [AI], surgical success rates, Epworth sleepiness score [ESS], SpO2, body mass index [BMI], and visual analog scale [VAS]) between both groups.

Results

A total of 40 studies with a total of 1940 patients were included, of which 1440 individuals who underwent tongue base reduction interventions (RF = 306, RF + UPPP = 656, and coblation + UPPP = 482) met inclusion criteria. Pooled analysis showed significant improvements in AHI (CBTR = -22.84, RFBOT = -11.14), AI (CBTR = 15.64, RFBOT = -5.26), ESS (CBTR = -7.59, RFBOT = -7.18), mean oxygen saturation (CBTR = 7.43, RFBOT = 4.25), mean BMI (CBTR = -0.69, RFBOT = -4.09), and snoring visual analog scale (CBTR = -16.20, RFBOT = -18.21). Surgical success rate (postoperative AHI < 20 and drop >50% from baselines) was 70% for CBTR and 43% for RFBOT.

Conclusion

Both interventions decreased sleep-related outcomes in adult patients with OSA. Coblation appears to exhibit superiority over radiofrequency with a similar safety profile. However, further studies with direct comparisons between both interventions must be performed.

A preoperative predictive study of advantages of airway changes after maxillomandibular advancement surgery using computational fluid dynamics analysis

The purpose of this study was to develop a simulation approach for predicting maxillomandibular advancement-induced airway changes using computational fluid dynamics. Eight patients with jaw deformities who underwent maxillomandibular advancement and genioglossus advancement surgery were included in this study. Computed tomography scans and rhinomanometric readings were performed both preoperatively and postoperatively. Computational fluid dynamics models were created, and airflow simulations were performed using computational fluid dynamics software; the preferable number of computational mesh points was at least 10 million cells. The results for the right and left nares, including simulation and postoperative measurements, were qualitatively consistent, and surgery reduced airflow pressure loss. Geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. Simulations were performed with either the right or left naris blocked, and the predicted values were similar to those found clinically. In addition, geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. These findings suggest that geometry prediction simulation facilitates the preoperative prediction of the postoperative structural outcome.

Computational analysis of airflow dynamics for predicting collapsible sites in the upper airways: a preliminary study

The present study aimed to detail the relationship between the flow and structure characteristics of the upper airways and airway collapsibility in obstructive sleep apnea. Using a computational approach, we performed simulations of the flow and structure of the upper airways in two patients having different facial morphologies: retruding and protruding jaws, respectively. First, transient flow simulation was performed using a prescribed volume flow rate to observe flow characteristics within upper airways with an unsteady effect. In the retruding jaw, the maximum magnitude of velocity and pressure drop with velocity shear and vortical motion was observed at the oropharyngeal level. In contrast, in the protruding jaw, the overall magnitude of velocity and pressure was relatively small. To identify the cause of the pressure drop in the retruding jaw, pressure gradient components induced by flow were examined. Of note, vortical motion was highly associated with pressure drop. Structure simulation was performed to observe the deformation and collapsibility of soft tissue around the upper airways using the surface pressure obtained from the flow simulation. At peak flow rate, the soft tissue of the retruding jaw was highly expanded, and a collapse was observed at the oropharyngeal and epiglottis levels.

NEW & NOTEWORTHY Aerodynamic characteristics have been reported to correlate with airway occlusion. However, a detailed mechanism of the phenomenon within the upper airways and its impact on airway collapsibility remain poorly understood. This study provides in silico results for aerodynamic characteristics, such as vortical structure, pressure drop, and exact location of the obstruction using a computational approach. Large deformation of soft tissue was observed in the retruding jaw, suggesting that it is responsible for obstructive sleep apnea.

Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism

The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔP_PAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔP_PAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔP_PAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔP_PAS=3.73×minCSA^-2.06. When the minCSA was <1cm², ΔP_PAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.

Genial tubercle advancement and genioplasty for obstructive sleep apnea: A systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis for studies evaluating genioplasty alone, genial tubercle advancement (GTA) alone, and GTA with hyoid surgery (GTA-HS) to treat obstructive sleep apnea (OSA).

DATA SOURCES

Ten databases.

REVIEW METHODS

Three authors searched through November 15, 2015.

RESULTS

1,207 studies were screened; 69 were downloaded; and 13 studies met inclusion criteria. A total of 111 patients were included, with 27 standard genioplasty, 10 modified genioplasty, 24 GTA, and 50 GTA-HS patients. For standard genioplasty, the apnea-hypopnea index (AHI) reduced from a mean ± standard deviation (M ± SD) of 18.8 ± 3.8 (95% confidence interval [CI] 17.6, 20.0) to 10.8 ± 4.0 (95% CI 9.5, 12.1) events/hour (relative reduction 43.8%), P value = 0.0001. Genioplasty improved lowest oxygen saturation (LSAT) from 82.3 ± 7.3% (95% CI 80.0, 84.7) to 86.8 ± 5.2% (95% CI 85.1, 88.5), P value = 0.0032. For modified genioplasty AHI increased by 37.3%. For GTA, the AHI reduced from an M ± SD of 37.6 ± 24.2 (95% CI 27.9, 47.3) to 20.4 ± 15.1 (95% CI 14.4, 26.4) events/hour (relative reduction 45.7%), P value = 0.0049. GTA improved LSAT from 83.1 ± 8.3% (95% CI 79.8, 86.4) to 85.5 ± 6.8% (95% CI 82.8, 88.2), P value = 0.2789. For GTA-HS, the AHI reduced from an M ± SD of 34.5 ± 22.1 (95% CI 28.4, 40.6) to 15.3 ± 17.6 (95% CI 10.4, 20.2) events/hour (relative reduction 55.7%), P value < 0.0001; GTA-HS improved LSAT from 80.1 ± 16.6% (95% CI 75.5, 84.7) to 88.3 ± 6.9% (95% CI 86.4, 90.2), P value = 0.0017.

CONCLUSION

Standard genioplasty, GTA and GTA-HS can improve OSA outcomes such as AHI and LSAT. Given the low number of studies, these procedures remain as an area for additional OSA research. Laryngoscope, 127:984-992, 2017.