Anatomy and physiology of the upper airway

The role of orthodontists in the multidisciplinary management of obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a complex disorder characterized by interruptions in breathing during sleep, leading to a range of adverse outcomes from reduced quality of life to serious health risks, including cardiovascular diseases and increased mortality.

MAIN BODY

This manuscript reviews the orthodontists' essential role in the multidisciplinary healthcare team tasked with managing OSA. It particularly highlights critical orthodontic interventions, such as surgical-orthodontic maxillomandibular advancement (MMA), mandibular advancement appliances (MAAs), and rapid maxillary expansion (RME). These interventions are pivotal in modifying craniofacial structures to enhance airway patency. The importance of conducting a thorough airway analysis is underscored, assessing the complete anatomical and functional factors contributing to airway obstruction.

CONCLUSION

The paper calls for increased collaborative research efforts to develop standardized, evidence-based orthodontic procedures for effectively managing OSA, aiming to improve patient outcomes through specialized, tailored interventions.

Severity of nasopharyngeal collapse before and after corrective upper airway surgery in brachycephalic dogs

OBJECTIVE

To determine the severity of nasopharyngeal collapse in brachycephalic dogs before and after corrective airway surgery.

ANIMALS

Twenty-three brachycephalic dogs (21 with clinical signs referrable to the upper airway) and nine clinically normal nonbrachycephalic dogs (controls).

METHODS

Dogs were evaluated with fluoroscopy awake and standing with the head in a neutral position. The magnitude of nasopharyngeal collapse was measured as the maximum reduction in the dorsoventral dimension of the nasopharynx during respiration and expressed as a percentage. Brachycephalic dogs were anesthetized, the airway evaluated, and corrective upper airway surgery (alaplasty, staphylectomy, sacculectomy, tonsillectomy) was performed. A cohort (n = 11) of the surgically treated brachycephalic dogs had fluoroscopy repeated a minimum of 6 weeks after surgery.

RESULTS

Median preoperative reduction in the dorsoventral dimensions of the nasopharynx was greater in brachycephalic dogs (65%; range: 8-100%) than in controls (10%; range: 1-24%, p = .0001). Surgery did not improve the reduction in dorsoventral diameter of the nasopharynx during respiration in brachycephalic dogs (n = 11) postoperatively (p = .0505).

CONCLUSION AND CLINICAL SIGNIFICANCE

Nasopharyngeal collapse was a common and sometimes severe component of brachycephalic airway obstruction syndrome in the cohort of dogs evaluated. The lack of significant postoperative improvement may represent a type II error, a failure to adequately address anatomical abnormalities that increase resistance to airflow, or inadequate upper airway dilator muscle function in some brachycephalic dogs.

Sleep-related breathing disorders in diaphragmatic pathologies

OBJECTIVE

The diaphragm is the most significant muscle involved in breathing. There are very few studies and cases evaluating sleep-related breathing disorders in diaphragmatic pathologies. This study compares preoperative and postoperative polysomnography (PSG) and pulmonary function test (PFT) results in diaphragmatic pathologies.

MATERIAL AND METHODS

The study included 28 patients who underwent video-assisted mini-thoracotomy (VATS) due to diaphragm eventration and paralysis between January 2014 and October 2019. Pulmonary function tests (PFT) and polysomnography (PSG) were performed preoperatively in all patients, and PSG and PFT were repeated 2 months after the surgery.

RESULTS

Twenty-five of the 28 patients were found to have apnea-hypopnea index (AHI) ≥ 5 (89%). A significant decrease in the preoperative TST, stage 3, and REM periods was observed. Nineteen of these patients (76%) were supine isolated or supine dominant. There was a marked improvement in AHI and PFT values after the surgery. Only five patients required a PAP device.

CONCLUSION

Doctors should perform PSG in patients with diaphragm pathologies, and these patients should be operated on after considering the comorbidities when OSA is detected.

Regional deposition of the allergens and micro-aerosols in the healthy human nasal airways

The nasal cavity is the inlet to the human respiratory system and is responsible for the olfactory sensation, filtering pollutant particulate matter, and humidifying the air. Many research studies have been performed to numerically predict allergens, contaminants, and/or drug particle deposition in the human nasal cavity; however, the majority of these investigations studied only one or a small number of nasal passages. In the present study, a series of Computed Tomography (CT) scan images of the nasal cavities from ten healthy subjects were collected and used to reconstruct accurate 3D models. All models were divided into twelve anatomical regions in order to study the transport and deposition features of different regions of the nasal cavity with specific functions. The flow field and micro-particle transport equations were solved, and the total and regional particle deposition fractions were evaluated for the rest and low activity breathing conditions. The results show that there are large variations among different subjects. The standard deviation of the total deposition fraction in the nasal cavities was the highest for 5 × 10 4 <impaction parameter (IP)< 1.125 × 10 5 with a maximum of 20%. The achieved results highlighted the nasal cavity sections that are more involved in the particle deposition. Particles with IP = 30,000 deposit more in the middle turbinate and nasopharynx areas, while for particles with IP = 300,000, deposition is mainly in the anterior parts (kiesselbach and vestibule regions). For small IP values, the amounts of deposition fractions in different regions of the nasal cavity are more uniform.

Comparison of radiofrequency and transoral robotic surgery in obstructive sleep apnea syndrome treatment

INTRODUCTION

Radiofrequency tissue ablation (RFTA) and transoral robotic surgery (TORS) are the methods used in OSAS surgery. We also aimed to compare the advantages and disadvantages of RF and TORS as treatment methods applied in OSAS patients in terms of many parameters, especially apnea hypopnea index (AHI).

MATERIALS AND METHODS

Patients were classified by performing a detailed examination and evaluation before surgery. 20 patients treated with anterior palatoplasty and uvulectomy -/+ tonsillectomy + RFTA (17 males, 3 females) and 20 patients treated with anterior palatoplasty and uvulectomy -/+  tonsillectomy + TORS (16 males, 4 females) were included in the study. PSG was performed preoperatively and postoperatively in all patients and Epworth sleepiness questionnaire was applied. All operations were performed by the same surgeon and these surgical methods -RF and TORS- were compared in terms of many parameters.

RESULTS

When the patients treated with RF and TORS were compared in operation time, length of hospitalization and duration of transition to oral feeding; all parameters were significantly greater in the patients treated with TORS.

CONCLUSIONS

TORS technique was found to be more successful than RF in terms of reduction of AHI value, correcting minimum arterial oxygen saturation value and decreasing Epworth Sleepiness Scale score.

Three-dimensional photography for the evaluation of facial profiles in obstructive sleep apnoea

BACKGROUND AND OBJECTIVE

Craniofacial structure is an important determinant of obstructive sleep apnoea (OSA) syndrome risk. Three-dimensional stereo-photogrammetry (3dMD) is a novel technique which allows quantification of the craniofacial profile. This study compares the facial images of OSA patients captured by 3dMD to three-dimensional computed tomography (3-D CT) and two-dimensional (2-D) digital photogrammetry. Measurements were correlated with indices of OSA severity.

METHODS

Thirty-eight patients diagnosed with OSA were included, and digital photogrammetry, 3dMD and 3-D CT were performed. Distances, areas, angles and volumes from the images captured by three methods were analysed.

RESULTS

Almost all measurements captured by 3dMD showed strong agreement with 3-D CT measurements. Results from 2-D digital photogrammetry showed poor agreement with 3-D CT. Mandibular width, neck perimeter size and maxillary volume measurements correlated well with the severity of OSA using all three imaging methods. Mandibular length, facial width, binocular width, neck width, cranial base triangle area, cranial base area 1 and middle cranial fossa volume correlated well with OSA severity using 3dMD and 3-D CT, but not with 2-D digital photogrammetry.

CONCLUSION

3dMD provided accurate craniofacial measurements of OSA patients, which were highly concordant with those obtained by CT, while avoiding the radiation associated with CT.