A novel implantable device for a minimally invasive surgical treatment of obstructive sleep apnea: design and preclinical safety assessment

Management of pharyngeal collapse in patients affected by moderate obstructive sleep apnoea syndrome

Objective

This study reports our experience in a selected cohort of patients affected by mild-moderate OSAS, without tonsillar obstruction, and treated with pharyngoplasty.

Methods

In a case-control retrospective study, we compared modified expansion sphincter pharyngoplasty (MESP) to modified barbed reposition pharyngoplasty (MBRP) in adult patients with oropharyngeal transversal collapse with a BMI ≤ 30 kg/m², and mild-moderate obstructive sleep apnoea syndrome (OSAS). A clinical evaluation, including collection of anthropometric data and sleep endoscopy, was performed. Six months after surgery, symptoms recording, clinical evaluation and polysomnography (PSG) were repeated.

Results

We enrolled 20 patients: 10 treated with MESP and 10 treated with MBRP. Mean apnoea-hypoapnoea index (AHI) was 22.8 (± 5.63). We observed in both groups a significant reduction of AHI and oropharyngeal obstruction (p = 0.01), with a success rate, according with Sher’s criteria, of 90% for MESP and 80% for MBRP, respectively. Post-surgical pain and snoring reduction were significantly lower with MBRP.

Conclusions

We recorded similar success rates for both techniques. MBRP may be considered better than MESP due to less surgical time, no potential mucosal damage, absence of knots, and faster recovery with less pain.

A computational model of upper airway respiratory function with muscular coupling

A two dimensional finite element model of upper airway respiratory function was developed emphasizing the effects of dilator muscular activation on the human retro-lingual airway. The model utilized an upright mid-sagittal computed tomography of the human head and neck to reconstruct relevant structures of the tongue, mandible, and the hyoid-related soft tissues, along with the retro-lingual airway. The reconstructed geometry was divided into fluid and solid domains and discretized into finite element (FE) meshes used for the computational model. Three cases were investigated: standing position; supine position; and supine position coupled with dilator muscle activation. Computations were performed for the inspiration stage of the breathing cycle, utilizing a fluid-structure interaction (FSI) method to couple structural deformation with airflow dynamics. The spatio-temporal deformation of the structures surrounding the airway wall were predicted to be in general agreement with known changes from upright to supine posture on luminal opening, as well as the distribution of airflow. The model effectively captured the effects of muscular stimulation on the upper airway anatomical changes, the flow characteristics relevant to airway reduction in the supine position and airway enlargement with muscle activation. The smallest airway opening in the retro-lingual section is predicted to occur at the epiglottic region in all the three cases considered, an unexpected vulnerable location of airway obstruction. The model also predicted that hyoid displacement would be associated with recovery from airway collapse. This information may be useful for building more complex models relevant to mechanisms and clinical interventions for obstructive sleep apnea.

Complications associated with surgical treatment of sleep-disordered breathing among hospitalized U.S. adults

The purpose of this cross-sectional study is to examine the relationship between surgical treatments for sleep-disordered breathing (SDB) and composite measure of surgical complications in a nationally representative sample of hospital discharges among U.S. adults. We performed secondary analyses of 33,679 hospital discharges from the 2002-2012 Nationwide Inpatient Sample that corresponded to U.S. adults (≥18 years) who were free of head-and-neck neoplasms, were diagnosed with SDB and had undergone at least one of seven procedures. Multivariate logistic regression models were constructed to estimate adjusted odds ratios (aOR) and 95% confidence intervals (CI), controlling for age, sex, race/ethnicity, obstructive sleep apnea (OSA) and obesity diagnoses. Positive associations were found between composite measure of surgical complications and specific procedures: palatal procedure (aOR = 12.69, 95% CI: 11.91,13.53), nasal surgery (aOR = 6.47, 95% CI: 5.99,6.99), transoral robotic assist (aOR = 5.06, 95% CI: 4.34-5.88), tongue base/hypopharynx (aOR = 4.24, 95% CI: 3.88,4.62), maxillomandibular advancement (MMA) (aOR = 3.24, 95% CI: 2.74,3.84), supraglottoplasty (aOR = 2.75, 95% CI: 1.81,4.19). By contrast, a negative association was found between composite measures of surgical complications and tracheostomy (aOR = 0.033, 95% CI: 0.031,0.035). In conclusion, most procedures for SDB, except tracheostomy, were positively associated with complications, whereby palatal procedures exhibited the strongest and supraglottoplasty exhibited the weakest association.

Palatal implant surgery effectiveness in treatment of obstructive sleep apnea: A numerical method with 3D patient-specific geometries

Obstructive sleep apnea (OSA) affects a large percentage of the population and is increasingly recognized as a major global health problem. One surgical procedure for OSA is to implant polyethylene (PET) material into the soft palate, but its efficacy remains to be discussed. In this study, we provide input to this topic based on numerical simulations. Three 3 dimensional (3D) soft palate finite element models including mouth-close and mouth-open cases were created based on three patient-specific computed tomography (CT) images. A simplified material modeling approach with the Neo-Hookean material model was applied, and nonlinear geometry was accounted for. Young's modulus for the implant material was obtained from uniaxial tests, and the PET implant pillars were inserted to the 3D soft palate model. With the finite element model, we designed different surgical schemes and investigated their efficacy with respect to avoiding the soft palate collapse. Several pillar schemes were tested, including different placement directions, different placement positions, different settings for the radius and the array parameters of the implant pillars, and different Young's moduli for the pillars. Based on our simulation results, the longitudinal-direction implant surgery improved the stiffness of the soft palate to a small degree, and implanting in the transverse direction was evaluated to be a good choice for improving the existing surgical scheme. In addition, the Young's modulus of the polyethylene material implants has an influence on the reinforcement efficacy of the soft palate.

A novel implantable device for the treatment of obstructive sleep apnea: clinical safety and feasibility

OBJECTIVE

Many cases of obstructive sleep apnea (OSA) involve collapse of the tongue base and soft palate during sleep, causing occlusion of the upper airway and leading to oxygen desaturation. Existing therapies can be effective, but they are plagued by patient adherence issues and the invasiveness of surgical approaches. A new, minimally invasive implant for OSA has been developed, which is elastic and contracts a few weeks after deployment, stabilizing the surrounding soft tissue. The device has had good outcomes in preclinical testing; this report describes the preliminary feasibility and safety of its implementation in humans.

PATIENTS AND METHODS

A prospective, multicenter, single-arm feasibility study was conducted. Subjects were adults with moderate-to-severe OSA who had previously failed or refused conventional continuous positive airway pressure treatment. Intraoperative feasibility data, postoperative pain, and safety information were collected for a 30-day postoperative period.

RESULTS

Forty subjects participated (37 men, three women; average age of 46.1 years); each received two tongue-base implants and two soft-palate implants. Surgical procedure time averaged 43 minutes. Postsurgical pain resolved readily in most cases; at 30 days post implantation, <20% of subjects reported pain, which averaged less than two out of ten. Adverse events were generally the mild and expected sequelae of a surgical procedure with general anesthesia and intraoral manipulation. The device was well tolerated. Implant extrusions were reported with soft-palate implants (n=12), while tongue-base implants required few revisions (n=2). Quantitative and qualitative sleep effectiveness outcomes (including full-night polysomnographic and quality-of-life measures) will be presented in a subsequent report.

CONCLUSION

Implantation of the device was feasible. Although a relatively high rate of extrusions occurred in the now-discontinued palate implants, tongue-base implants were largely stable and well tolerated. The minimally invasive and maintenance-free implant may provide a new alternative to higher morbidity surgical procedures.