Morpho-Volumetric Changes of the Pharyngeal Airway With Traumatic Maxillofacial Injuries: A Retrospective Radiographic Study

BACKGROUND

When dealing with traumatized patients, it is crucial to prioritize securing their airway. However, intubating someone who has sustained significant facial injuries can pose difficulties, as the narrow and altered shape of their upper airway may impede their ability to open their mouth. In light of this, the purpose of this study is to evaluate the volumetric and morphological alterations to the upper airway resulting from facial trauma by utilizing computed tomography (CT) scans.

METHOD

This is a single-centered retrospective analytical study. This study included CT scans of patients with traumatic facial injuries admitted to King Fahad Hospital in Madinah, Saudi Arabia. Study variables included age, gender, body mass index (BMI), fractured bones, airway symmetry, and airway volume. Using the 3D Slicer software (Slicer Community, USA), a three-dimensional model of the pharyngeal airway was constructed from the CT scan to evaluate symmetry and volume. IBM SPSS Statistics for Windows, version 23 (released 2013; IBM Corp., Armonk, New York, United States) was used to analyze data.

RESULTS

Among the screened scans, 136 cases with traumatic facial injuries were included in the study. Age ranged from four to 91 years, with a mean of 28.26 (±14.9). Mandibular and zygomatic fractures were the most common, with 71 (52.2%) and 69 (50.7%) cases, respectively. The pharyngeal airway was symmetric in 111 (81.6%) cases and not symmetric in the other 25 (18.4%) cases. A significant association was found between the side of the fracture and airway asymmetry in mandibular fractures (p-value = 0.03). The total airway volume in the displaced mandibular fractures showed a statistically significant decrease (p-value = 0.019). The fracture sites were not statistically linked to airway asymmetry except for parasymphyseal and symphyseal fractures, with a p-value of 0.038 and 0.041, respectively.

CONCLUSION

The study findings suggest that the pharyngeal airway is not usually compromised in most facial bone fractures; however, bilateral displaced mandibular fractures have the potential to diminish the pharyngeal airway volume, especially in fractures involving the symphysis and parasymphysis area.

Effects of atomoxetine plus a hypnotic on obstructive sleep apnea severity in patients with a moderately collapsible pharyngeal airway

STUDY OBJECTIVES

Pharmacotherapy for obstructive sleep apnea (OSA) regained consideration after the discovery that atomoxetine and oxybutynin greatly reduced OSA severity. However, atomoxetine and oxybutynin reduced the arousal threshold and may therefore be poorly tolerated in patients with OSA and disturbed sleep. As a result, we tested the combination of atomoxetine plus 2 hypnotics in patients with OSA. The effects of atomoxetine plus: (1) trazodone (Ato-Trazo) and (2) lemborexant vs placebo on apnea-hypopnea index, hypoxic burden, arousal threshold, and total sleep time were assessed. Drug safety was also ascertained, together with the effect of the combinations on other OSA traits, self-reported sleep quality, and next-day alertness.

METHODS

Following a baseline study, 15 patients with mild-to-severe OSA with moderate upper airway collapsibility were administered Ato-Trazo, atomoxetine and lemborexant, and matching placebo according to a double-blind, randomized, crossover design. Apnea-hypopnea index and other objective outcomes were calculated from 3 clinical, in-laboratory polysomnograms.

RESULTS

Ato-Trazo significantly reduced apnea-hypopnea index from a median [interquartile range] of 18.2 [11.8 to 31.3] on placebo to 7.4 [5.4 to 16.1] events/h, P = .024, and hypoxic burden from 46.3 [25.1 to 88.3] on placebo to 18.7 [14.9 to 43.5], P = .003. This effect was likely driven by an increase in polysomnography-estimated pharyngeal muscle activity during the events (P = .029). Atomoxetine and lemborexant had smaller statistically insignificant effects. Contrary to atomoxetine and oxybutynin, Ato-Trazo and atomoxetine and lemborexant did not reduce the arousal threshold. Both combinations had no effect on total sleep time but worsened self-reported sleep quality.

CONCLUSIONS

Ato-Trazo has the potential to become a useful drug combination, however, longer trials are needed to determine the best dosage and the subgroup of patients who may benefit most from this combination.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: Crossover Trial of AD182 and AD504 in Obstructive Sleep Apnea; URL: https://clinicaltrials.gov/ct2/show/NCT04645524; Identifier: NCT04645524.

CITATION

Corser B, Eves E, Warren-McCormick J, Rucosky G. Effects of atomoxetine plus a hypnotic on obstructive sleep apnea severity in patients with a moderately collapsible pharyngeal airway. J Clin Sleep Med. 2023;19(6):1035-1042.

The Efficacy of the Partial Glossectomy for Prevention of Airway Volume Reduction in Orthognathic Surgery of Class III Patients

The aim of this study was to evaluate the effects of a partial glossectomy on volumetric changes of pharyngeal airway space (PAS) in patients with mandibular setback surgery. Overall, 25 patients showing clinical features related to macroglossia treated with mandibular setback surgery were included in this retrospective study. Subjects were divided into two groups: the control group (G1, n = 13, with BSSRO) and the study group (G2, n = 12, with both BSSRO and partial glossectomy). The PAS volume of both groups was measured by the OnDemand 3D program on CBCT taken shortly before operation (T0), 3 months post-operative (T1), and 6 months post-operative (T2). A paired t-test and repeated analysis of variance (ANOVA) were used for statistical correlation. Total PAS and hypopharyngeal airway space were increased after operation in Group 2 compared to Group 1 (p < 0.05), while oropharyngeal airway space showed no significant statistical difference with the tendency of increasing. The combination of partial glossectomy and BSSRO surgical techniques had a significant effect on increasing the hypopharyngeal and total airway space in class III malocclusion patients (p < 0.05).

Three-dimensional assessment of pharyngeal airway in individuals with myotonic dystrophy type 1

Background/aim

The objectives of this study were to assess pharyngeal airway volume (PAV) in patients with myotonic dystrophy type 1 (DM1) by cone-beam computerized tomography (CBCT) and to evaluate the impact of diaphragm thickness and pulmonary function tests on PAV.

Materials and methods

Thirty DM1 patients (10 female and 20 male; mean age 42.40 ± 12.07) were included in the study. Age and sex-matched thirty patients were participated as control group. In DM1 group pulmonary function tests (PFT) were performed. Independent t-test was used to compare PAV values of patients with DM1 and control group. The Mann–Whitney U test was used to compare the parameters according to sex ( p < 0.05). Pearson and Spearman correlation tests were used to evaluate the relationships between parameters of DM1 patients (p < 0.05). A multiple linear regression analysis was performed to explain the PAV with parameters that showed positive correlation with PAV.

Results

Age of onset and disease duration were 22.37 ± 8.45 and 20.03 ± 12.08, respectively, in patients with DM1. PAV values of control group were significantly lower than DM1 group ( p < 0.001). Forced expiratory volume in 1 s and forced volume vital capacity values were higher in males than females in DM1 group according to sex ( p < 0.001). PAV values were greater in male patients than females of the DM1 group ( p = 0.022). Diaphragm thickness in DM1 group after inspiration and expiration were 2.60 ± 0.65 and 1.94 ± 0.40, respectively. According to the regression analysis, DTai and FVC were significantly explained the PAV.

Conclusion

PAV was higher in DM1 group. There was a significant positive correlation between diaphragm thickness, pulmonary functions, and PAVs of DM1 patients. The amount of the PAV was mostly influenced by DTai and FVC. It is recommended to evaluate the PAV in patients with DM1 because of impaired respiratory functions and pharyngeal muscle involvement.

Does rapid maxillary expansion enlarge the nasal cavity and pharyngeal airway? A three-dimensional assessment based on validated analyses

OBJECTIVES

To evaluate the three-dimensional changes following rapid maxillary expansion (RME) of the nasal cavity (NC) and pharyngeal airway (PA) in growing patients, using innovative and validated evaluation methods and to investigate whether a correlation between skeletal expansion and increase in airway volume exists.

SETTINGS AND SAMPLE POPULATION

Records of patients who had cone beam computed tomography taken before and after orthodontic treatment with or without RME were retrospectively collected and divided into two groups: (a) RME, 39 patients (mean age 10.40 ± 1.74 years); and (b) control, 29 patients, matched for age (mean age 11.07 ± 1.45 years) and follow-up period.

MATERIAL AND METHODS

Total and partial volumes of the NC and the PA were calculated. The PA centerline was determined to assess the minimal cross-sectional area and hydraulic diameter. Paired and unpaired t test were applied to compare the difference between time points and between groups. One-way ANOVA and post hoc Tukey's tests were used to compare subgroups with respect to changes in palatal width and lacrimal ducts distance.

RESULTS

All of the NC, PA and skeletal parameters were significantly enlarged after RME. The NC volume and inter-molar distance in the RME were significantly larger compared to the control group. The initially lower mean values of minimal cross-sectional area and hydraulic diameter in the RME group when compared to the control group normalized after RME treatment.

CONCLUSIONS

Based on validated analyses, the NC volume increase was evident after RME in the long term after controlling for growth.

Determining the short-term effects of different maxillary protraction methods on pharyngeal airway dimensions

OBJECTIVE

This study sought to evaluate the effects of different maxillary protraction methods on the pharyngeal airway in Class III patients with maxillary retrognathia.

SETTING AND SAMPLE POPULATION

A total of 59 individuals (31 females and 28 males) with a mean age of 11.38 ± 1.24 years were included in this study.

MATERIAL AND METHODS

Fifty-nine treated maxillary retrognathic patients who underwent different protraction methods were evaluated. Twenty patients treated with RME (Rapid Maxillary Expansion) made up the first group, and 20 patients treated with 5-week Alt-RAMEC (Alternate Rapid Maxillary Expansion and Constriction) protocol comprised the second group. Lastly, 19 patients on whom face masks with miniplates were applied were included in the skeletal anchorage (SA) group. Sixteen linear and four areal pharyngeal airway measurements were made on lateral cephalograms before and after treatment. Differences between the groups were assessed using analysis of variance (ANOVA) tests.

RESULTS

The mean maxillary protraction levels were determined as 2.7, 3.69 and 4.01 mm in the RME, Alt-RAMEC and SA groups, respectively. In the nasopharynx, AD1-PNS, AD2-PNS, PNS-Ba and PNS-Ho measurements revealed a significant increase in the SA group compared to the other groups (P < .05). In the oropharynx, PNS-Ep measurement increased significantly in the RME group (P < .05). In the total pharyngeal airway area, an increase was detected in the SA, Alt-RAMEC, and RME groups.

CONCLUSION

The most effective protraction method in terms of pharyngeal airway dimensions, especially in the nasopharynx, is the application of the face mask with skeletal anchorage. A greater increase in vertical airway length (PNS-Ep) was observed with RME.

Comparison of Volumetric Dimensions of Pharyngeal Airway for Different Dentofacial Skeletal Patterns Using Cone Beam Computed Tomography

INTRODUCTION

After a century of controversies, we are still not certain on the relationship between airway volume and facial morphology.

OBJECTIVE

To measure nasopharyngeal airway volume and compare it among different skeletal patterns.

MATERIALS AND METHODS

Forty five CBCT scans of patients between sixteen to twenty five years were used in the study. The nasopharyngeal airway was divided into upper, middle and lower segments. CBCT images were grouped into skeletal class I, class II and class III.

RESULTS

There was highly significant difference in upper (p=0.001) and middle pharyngeal airway volume (p<0.001) among 3 skeletal groups. Lower pharyngeal airway volume was also statistically significant (p=0.051) among 3 groups. Total pharyngeal airway volume did not show any significant correlation.

CONCLUSION

Nasopharyngeal airway volume seems to play a role in different skeletal patterns.

Three-Dimensional Analysis of the Pharyngeal Airway Volume and Craniofacial Morphology in Patients With Bilateral Cleft Lip and Palate

OBJECTIVE

This study aimed to determine the correlations between the craniofacial morphology and pharyngeal airway volume in patients with complete bilateral cleft lip and palate (BCLP).

DESIGN

Retrospective study.

SETTING

Tertiary hospital.

PARTICIPANTS

Twenty-seven patients with complete BCLP and 27 class I control patients, aged 10 to 14 years.

MAIN OUTCOME MEASURE

The pharyngeal airway volume and craniofacial morphology were evaluated using cone-beam computed tomography. Measurements were compared between groups and any correlations were identified.

RESULTS

A significantly smaller total pharyngeal airway volume (TPV), oropharyngeal airway volume, and upper (UOPV) and lower (LOPV) oropharyngeal airway volume were found in patients with BCLP than in class I control patients, with no difference in the nasopharyngeal volume between groups. Furthermore, the craniofacial morphology measurements of N-Me, S-Go, Or-C, Ptm-C, Me-C, Co-Go, Go-Me, Ptm-Or, N-S-Ar, and Ar-Go-Me significantly differed between the BCLP and control groups (all P < .05). Multiple regression analysis indicated that Ptm-C and Me-C; Ptm-C, Or-C, and Me-C; and Me-C explained 20.3%, 38.9%, and 17.1% of the variations in TPV (P = .025), UOPV (P = .002), and LOPV (P = .018), respectively.

CONCLUSIONS

Total pharyngeal airway volume, TPV, OPV, UOPV, and LOPV were significantly smaller in patients with BCLP than in class I controls. In patients with BCLP, the maxilla showed inhibited sagittal development and a retrograde position; moreover, the pharyngeal airway volume was weakly associated with the position of the maxilla and mandible relative to the coronal plane.

Airway Analysis in Skeletal Class I and Class II Subjects with Different Growth Patterns: A 2D Cephalometric Study

OBJECTIVE

A two-dimensional cephalometric study was carried out to assess the airway among individuals with Class I and Class II skeletal base.

MATERIALS AND METHODS

Class II subjects were further categorized into horizontal and vertical growers and average growth patterns to check the possible relationship between the facial skeleton and pharyngeal airway. Lateral cephalograms of 150 subjects were obtained using standard protocol in natural head position (NHP). Nasopharyngeal and oropharyngeal linear, and angular and nasopharyngeal area measurements were obtained using standardized tracing technique. Analysis of variance (ANOVA), level of significance, and post hoc Turkey's test were performed to assess the correlation between skeletal pattern of the individual and airway dimension. Gender discrimination was assessed using independent sample t test.

RESULTS

In linear measurements, significant differences were observed among upper pharynx (0.039), adenoid tissue 1 (0.036), and adenoid tissue 2 (0.01). In angular measurements, differences were observed with angle of nasopharynx (0.008). The nasopharyngeal area measurements were also associated with significant difference (0.038) with Class II vertical growers less than those with Class I average and Class II horizontal groups.

CONCLUSION

Class II vertical growers had significantly reduced nasopharyngeal airways.

Pharyngeal airway dimension in patients before and after treatment of myofascial pain syndrome

Objective: This study aimed: (1) to assess the localization of the anatomic landmarks of the pharyngeal airway on cone beam computed tomography (CBCT) images; and (2) to evaluate if resolution of myofascial pain syndrome (MPS) changed the airway dimensions.Methods: Twenty-nine patients with pre- and post-treatment CBCT scans were randomly selected to locate five landmarks twice, with a two-week interval. The same landmarks were used to measure the airway volume and minimal cross-sectional area (CSA_min).Results: The intra-observer reliability (ICC) was 0.99-1.00 for volumetric and CSA_min measurements, based on the five landmarks used. The paired t test showed no significant difference in the airway volume (p = 0.68) and CSA_min (p = 0.96).Discussion: The outcomes showed that the landmarks used had excellent ICCs for the volumetric and CSA_min measurements. There was no change in volume and CSA_min of the pharyngeal airway after resolution of MPS.

Three-dimensional assessment of the pharyngeal airway in Japanese preschoolers with orofacial clefts

OBJECTIVES/HYPOTHESIS

Individuals with orofacial clefts often experience respiratory problems because of nasopharyngeal abnormalities. Pharyngeal airway morphology is thought to differ among the various cleft types. We measured three-dimensional (3D) airway volume using cone-beam computed tomography (CBCT) analysis to evaluate and compare pharyngeal airways in Japanese preschoolers with and without orofacial clefts.

STUDY DESIGN

Retrospective case-control study.

METHODS

We enrolled 83 subjects (37 boys, 46 girls; mean age = 4.66 ± 0.56 years) with nonsyndromic orofacial clefts and 16 noncleft healthy subjects (seven boys, nine girls; mean age = 5.30 ± 0.52 years) as controls. The subjects were divided into five groups. Four groups were based on the cleft type: isolated cleft palate, unilateral cleft lip and alveolus), unilateral cleft lip and palate, and bilateral cleft lip and palate. The fifth group included the noncleft controls. All subjects were examined with CBCT, and the 3D airway volume was measured. We analyzed group differences statistically using analysis of covariance with the Bonferroni post hoc pairwise comparison tests for the corrected means.

RESULTS

Compared with the noncleft group, each cleft group exhibited significantly decreased total and nasal airway volumes and increased superior and inferior pharyngeal airway volumes. The differences were all statistically significant.

CONCLUSIONS

Our findings suggest that anatomical differences exist in pharyngeal airway volumes among various cleft groups and in those without a cleft.

LEVEL OF EVIDENCE

3b Laryngoscope, 130:533-540, 2020.

Changes in Hyoid Bone Position and Cross-sectional Area of Pharyngeal Airway After Oral Cancer Surgery

AIM

To investigate hyoid bone position and cross-sectional area (CSA) of pharyngeal airway space (PAS) for assessing postoperative airway change after oral cancer surgery with concurrent neck dissection (ND).

PATIENTS AND METHODS

Fifty-two patients who underwent oral cancer surgery with concurrent ND were retrospectively evaluated by grouping based on ND type and reconstruction. Computed tomographic data were analyzed three-dimensionally before and after surgery.

RESULTS

The hyoid bone position differed significantly between preoperative and postoperative images in the anteroposterior and supero-inferior directions (p<0.05). CSA was increased after ND (p<0.05). The hyoid bone was positioned more superiorly in ND and fibular free-flap reconstruction groups compared to other groups (p<0.05). CSA of the PAS increased as the hyoid bone moved forward (p<0.05).

CONCLUSION

The hyoid bone moves forward and upward after oral cancer surgery with concurrent ND, which increases the CSA of the PAS. These results provide the useful insight into managing a patient's airway after oral cancer surgery with ND.

Changes in position of the hyoid bone and volume of the pharyngeal airway after mandibular setback: three-dimensional analysis

Important aspects of orthognathic surgery are the effects of skeletal movement and changes in the position of the hyoid bone, tongue, soft palate, and dimensions of the pharyngeal airway. Our aims were to evaluate the 3-dimensional changes in the pharyngeal airway and in the position of the hyoid bone after mandibular setback in 30 patients who were diagnosed with mandibular prognathism and were treated by intraoral vertical ramus osteotomy (IVRO). Three-dimensional cone-beam computed tomographic (CT) images were obtained preoperatively, one month postoperatively, and one year postoperatively. The total pharyngeal volume decreased between the preoperative state and one month and one year afterwards. The hyoid bone had moved 2.0mm posteriorly and 3.15mm superiorly by one month postoperatively. The position of the hyoid bone was affected by changes in posterior and superior movement of the B point at one month (r=0.44, p=0.015 and R=0.63, p=0.000, respectively) and also by superior movement of the B point at one year (r=0.57, p=-0.001). There was an advantageous relation between posterior positional changes in the B point (mandibular setback), and volumetric changes in the hypopharyngeal and total pharyngeal airway, so maxillofacial surgeons should consider the reduction in airway when planning excessive mandibular setback.

Comparison of hyoid bone positions and pharyngeal airway dimensions in different body mass index percentile adolescent subjects

OBJECTIVE

Increased body mass index (BMI) is a growing problem worldwide and can affect medical conditions through morphological structures. The purpose of this study was to examine the hyoid bone position and pharyngeal airway dimensions on the sagittal section in different BMI percentile adolescent subjects.

METHODS

Fifty-five adolescent patients were subdivided into three groups, considering their BMI percentiles: Normal-weight (16 subjects), overweight (20 subjects), and obese (19 subjects). A total of 13 linear and angular parameters of head posture angle, pharyngeal airway dimensions, and hyoid bone positions were investigated on 55 lateral cephalometric radiographs.

RESULTS

Except for one hyoid bone measurement (RGN-H), there was no significant difference among groups. The RGN-H distances of obese and overweight adolescent subjects were higher than normal-weight adolescent subjects.

CONCLUSION

Obese, overweight, and normal-weight adolescent subjects were likely to have similar hyoid bone position and pharyngeal airway dimensions.

Pharyngeal airway dimensional changes after premolar extraction in skeletal class II and class III orthodontic patients

OBJECTIVE

To assess and compare the changes in pharyngeal airway space dimensions following orthodontic treatment of skeletal class II and class III facial deformities with premolar extraction.

MATERIALS AND METHODS

Sixty pre and posttreatment lateral cephalometric radiographs of patients who underwent fixed orthodontic treatment with premolar extraction were collected. The sample was divided into two groups - 32 patients with skeletal class II and 28 patients with skeletal class III malocclusion. Both groups were subdivided into growing patients (<16 years old) and adults (>16 years old). Nasopharyngeal, palatopharyngeal, and glossopharyngeal airway space dimensions were measured in the pretreatment (T0) and posttreatment (T1) cephalometric radiographs using Dolphin Imaging 11.7 software. Two-way, repeated-measures analysis of variance was used to assess the in-treatment changes.

RESULTS

Nasopharyngeal airway dimension showed similar significant increase in class II (P = 0.042) and class III (P = 0.049) patients from T0 to T1, whereas palatopharyngeal and glossopharyngeal dimensions were insignificantly decreased in both groups. However, both malocclusions followed the same pattern of changes in relation to airway dimensions. In addition, no significant statistical difference was found in the airway spaces between growing and adult patients.

CONCLUSIONS

Extraction of premolars did not affect the pharyngeal dimensions except those of the nasopharynx, which showed a significant increase after extraction in both groups.

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

Objectives

Perioperative 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.

Methods

CT 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.

Results

Estimated 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.

Conclusion

Pharyngeal 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 Evidence

4.

Pharyngeal airway changes following maxillary expansion or protraction: A meta-analysis

The aim of this meta-analysis was to investigate the changes in airway dimensions after rapid maxillary expansion (RME) and facemask (FM) protraction. Using PubMed, Medline, ScienceDirect and Web of Science, only controlled clinical trials, published up to November 2016, with RME and/or FM as keywords that had ≥6 months follow-up period were included in this meta-analysis. The changes in pharyngeal airway dimension in both two-dimensional and three-dimensional images were included in the analysis. Nine studies met the criteria. There are statically significant changes in upper airway and nasal passage airway in the intervention groups as compared to the control groups, assessed in two-dimensional and three-dimensional images. However , in the lower airway and the airway below the palatal plane, no statistically significant changes are seen in 2D and 3D images. RME/FM treatments might increase the upper airway space in children and young adolescents. However, more RCTs and long-term cohort studies are needed to further clarify the effects on pharyngeal airway changes.

Feedback modulation of surrounding pressure determines the onset of negative effort dependence in a collapsible tube bench model of the pharyngeal airway

Negative effort dependence (NED), decreased airflow despite increased driving pressure, has been proposed as a specific obstructive sleep apnea (OSA) phenotypic characteristic. We examined conditions under which NED occurs in a collapsible tube, pharyngeal airway bench model with the chamber enclosed, focusing on relationships with surrounding pressure levels and longitudinal strain. Using a vacuum source, graded airflows (V̇; 0-5 l/s) were generated through a thin-walled latex tube enclosed within a rigid, cylindrical chamber, sealed with initial chamber pressures (Pci) of 0-5 cmH₂O (separate runs), or opened to the atmosphere. Upstream minus downstream pressure (Pu - Pd), maximum airflow (V̇_max), and chamber pressure (Pc) were measured at 0-50% longitudinal strain. NED occurred across the range of Pci and strains studied but was most pronounced for the chamber open condition. With a sealed chamber, V̇ increased and Pc decreased with increasing Pu - Pd until the onset of NED at V̇_max and a Pc value that was designated as critical (Pcc). Pcc was lowest (-17 cmH₂0) and V̇_max was highest (~5 l/s) with chamber sealed: Pci = 0 cmH₂O and 12.5 to 25% strain. We conclude that for our collapsible tube model, the achievable V̇_max before the onset of NED depends on both the initial conditions (Pci and strain) and the dynamics of feedback between driving pressure and chamber pressure (chamber sealed vs. open). NED-based phenotypic analyses for OSA may need to focus on potential feedback control mechanisms (eg lung volume change, muscle activity) that may link peripharyngeal tissue pressure levels to driving pressures for airflow.NEW & NOTEWORTHY A collapsible tube, pharyngeal airway bench model was used to study the role of surrounding pressure and longitudinal wall strain at the onset of negative effort dependence (NED). NED occurred to varying degrees across all conditions tested, but maximum airflow was achieved with 1) low initial surrounding pressure, 2) a feedback mechanism between surrounding pressure and driving pressure; and 3) a moderate amount of strain applied. Potential impacts on OSA phenotypic analyses are discussed.

Comparing the efficacy and safety of laryngeal mask airway, streamlined liner of the pharyngeal airway and I-gel following tracheal extubation

Adverse events following surgical operations are common complications due to removal of tracheal tube in contrast to the tracheal intubation. Awareness about the new methods and strategies for tracheal tube extubation is necessary for a safe and successful extubation. Therefore, we aimed to assess the safety and efficacy of laryngeal mask airway (LMA), streamlined liner of the pharyngeal airway (SLIPA) and I-gel in extubation time of tracheal tube. A one-single randomized clinical trial was conducted in 105 eligible patients in three groups including LMA, SLIPA and I-gel. The patients were under surgery after general anesthesia with propofol (2-3 mg/kg) and fentanyl (1-2 μg/kg). Hemodynamic responses and extubation consequences including coughing rate, laryngospasm, airway obstruction, apnea, breath holding and straining of patients, vomiting, and need for re-intubation were recorded every 5 minutes since inserting of supraglottic airway devices (SADs) until patients restore consciousness. Analysis of data was conducted in SPSS software by analysis of variance (ANOVA) and ANOVA for repeated measurements tests. The overall successful insertion was 100% for LMA and I-Gel and this rate was 97.1% for SLIPA method. A significant decrease was observed in trend of hemodynamic responses in all three groups. Nevertheless, the MBP was lower in LMA group and lower HR was observed in I-Gel and higher HR occurred in SLIPA (P < 0.05). Three groups was same statistically regarding sore throat, vomiting, coughing, breath holding, apnea, laryngospasm, and re-intubation need (P > 0.05). However, the incidence rate of apnea, and laryngospasm, as well as re-intubation need in SLIPA group was 2.9%, respectively. LMA, I-GEL and SLIPA could be considered as useful and safe devices for ventilation control after tracheal tube removal at the end of operation. Three devices were same regarding to sore throat, vomiting, coughing, and breath holding. However, LMA showed lower side effects while SLIPA was related to more occurrences of apnea, laryngospasm, and re-intubation need.

Long-term influence of mandibular advancement on the volume of the posterior airway in skeletal Class II-patients: a retrospective analysis

In the past, maxillomandibular advancement has resulted in considerable improvement in the volume of the posterior airway space. The objective of the present study was to find out how mandibular advancement without maxillary involvement would affect the posterior airway space in patients with mandibular retrognathism. Cone-beam computed tomographic (CT) scans were done for 20 patients before, and six months after, mandibular advancement. Cephalometric analysis at both time points included 2-dimensional and 3-dimensional assessment of the upper airway. Eight men and 12 women presented a preoperative mean (SD) Wits value of 7.4 (1.54) mm, with an airway area of 7.11 (1.88) cm² and a volume of 14.92 (4.46) cm³. Six months postoperatively they showed a Wits value of 2.7 (0.41) mm, an airway area of 11.33 (3.49) cm², and a volume of 25.7 (6.10) cm³. There was a mean (range) enlargement of 59 (22-82) % of the area and 73 (29-108) % of the volume. A preoperative Wits value of 8mm or more correlated significantly with a larger increase of the posterior airway space (p=0.002). At the same time, an improvement in the Wits value of 4.5mm or more correlated significantly with an increase in volume (p=0.016). The effect of mandibular advancement on the posterior airway space was significant, and the volumetric effect seems to be even more relevant than the two-dimensional changes.

Volumetric changes in pharyngeal airway in Class II division 1 patients treated with Forsus-fixed functional appliance: A three-dimensional cone-beam computed tomography study

Objective:

Recent years have witnessed a renewed interest to determine a quantifiable relationship between mandibular advancement performed with an orthodontic appliance and the resulting airway volume. The study was conducted to evaluate the volumetric changes in pharyngeal airway space using cone-beam computed tomography (CBCT) in Class II division 1 patients with retrognathic mandible treated by Forsus-fixed functional appliance and to compare them with their pretreatment findings.

Materials and Methods:

Thirty patients with Class II division 1 malocclusion of age group 10–17 years were selected randomly and evaluated for changes in pharyngeal airway volume with and without Forsus-fixed functional appliance. Patients in each group underwent CBCT scan of head and neck region at pretreatment stage and 6 months after the initial scan. Institutional approval for the project was obtained from the Ethical Committee. Volumetric changes of upper (oropharynx) and lower (hypopharynx) pharyngeal airways were measured on scanogram using computer software and intragroup comparisons were done.

Results:

There was a statistically significant increase in the volume of both hypopharynx and oropharynx and also total airway volume in patients treated with Forsus-fixed functional appliance. Three-dimensional reconstruction of the airway also demonstrates a considerable increase in pharyngeal airway space.

Conclusion:

Forsus-fixed functional appliance can be a promising appliance for improving pharyngeal airway volume in Class II division 1 patients with retrognathic mandible thus preventing obstructive sleep apnea and other respiratory problems in future. However, the long-term implications of this treatment modality need further consideration and a longer period of follow-up.

Craniofacial and pharyngeal airway morphology in patients with acromegaly

OBJECTIVE

The aim of this study was to assess differences in craniofacial characteristics, upper spine and pharyngeal airway morphology in patients with acromegaly compared with healthy individuals.

MATERIALS AND METHODS

Twenty-one patients with acromegaly were compared with 22 controls by linear and angular measurements on cephalograms. The differences between the mean values of cephalometric parameters were analyzed with Mann-Whitney U-test.

RESULTS

With respect to controls, anterior (p<0.05), middle (p<0.01) and posterior (p<0.05) cranial base lengths were increased, sella turcica was enlarged (p<0.001) and upper spine morphology demonstrated differences in the height of atlas (p<0.01) and axis (p<0.05) in patients with acromegaly. Craniofacial changes were predominantly found in the frontal bone (p<0.01) and the mandible (p<0.05). As for the airway, patients with acromegaly exhibited diminished dimensions at nasal (p<0.001), uvular (p<0.01), mandibular (p<0.01) pharyngeal levels and at the narrowest point of the pharyngeal airway space (p<0.001) compared to healthy controls. Soft palate width was significantly higher (p<0.001) and the hyoid bone was more vertically positioned (p<0.01) in patients with acromegaly.

CONCLUSIONS

Current results point to the importance of the reduced airway dimensions and that dentists and/or orthodontists should be aware of the cranial or dental abnormalities in patients with acromegaly.

Arousal from sleep does not lead to reduced dilator muscle activity or elevated upper airway resistance on return to sleep in healthy individuals

STUDY OBJECTIVES

To compare changes in end-tidal CO2, genioglossus muscle activity and upper airway resistance following tone-induced arousal and the return to sleep in healthy individuals with small and large ventilatory responses to arousal.

DESIGN

Observational study.

SETTING

Two sleep physiology laboratories.

PATIENTS OR PARTICIPANTS

35 men and 25 women with no medical or sleep disorders.

INTERVENTIONS

Auditory tones to induce 3-s to 15-s cortical arousals from sleep.

MEASUREMENTS AND RESULTS

During arousal from sleep, subjects with large ventilatory responses to arousal had higher ventilation (by analytical design) and tidal volume, and more marked reductions in the partial pressure of end-tidal CO2 compared to subjects with small ventilatory responses to arousal. However, following the return to sleep, ventilation, genioglossus muscle activity, and upper airway resistance did not differ between high and low ventilatory response groups (Breath 1 on return to sleep: ventilation 6.7±0.4 and 5.5±0.3 L/min, peak genioglossus activity 3.4%±1.0% and 4.8%±1.0% maximum, upper airway resistance 4.7±0.7 and 5.5±1.0 cm H2O/L/s, respectively). Furthermore, dilator muscle activity did not fall below the pre-arousal sleeping level and upper airway resistance did not rise above the pre-arousal sleeping level in either group for 10 breaths following the return to sleep.

CONCLUSIONS

Regardless of the magnitude of the ventilatory response to arousal from sleep and subsequent reduction in PETCO2, healthy individuals did not develop reduced dilator muscle activity nor increased upper airway resistance, indicative of partial airway collapse, on the return to sleep. These findings challenge the commonly stated notion that arousals predispose to upper airway obstruction.

Evaluation of hyoid bone position and its correlation with pharyngeal airway space in different types of skeletal malocclusion

Introduction:

The hyoid bone and its relation with the pharyngeal space in health and disease has been an intriguing subject for years.

Aim:

This study attempts to evaluate the hyoid bone position and to ascertain any correlations with pharyngeal airway space in skeletal class I, II, and III malocclusions.

Materials and Methods:

McNamara's airway analysis was carried out to assess the upper and lower airway widths and Hyoid triangle analysis by Bibby and Preston was carried out to determine the position of the hyoid bone.

Conclusion:

A positive correlation was found between the lower airway and horizontal distance from the hyoid bone to the retrognathion in class I skeletal pattern with average growth pattern.