Narrowest Cross-sectional Area Research Articles

Threshold of the upper airway cross-section for hypopnea onset during sleep and its identification under waking condition

BackgroundThere is currently no method that can predict whether or under what condition hypopnea, even obstructive sleep apnea (OSA), will occur during sleep for individuals based on credible parameters measured under waking condition. We propose a threshold concept based on the narrowest cross-sectional area of the upper airway (CSA-UA) and aim to prove our hypothesis on the threshold of the area for hypopnea onset (TAHO), which can be used as an indicator of hypopnea onset during sleep and measured while awake.MethodsWe performed magnetic resonance imaging for 20 OSA patients to observe CSA-UA changes during fluid accumulation in the neck caused by elevating their legs, and identified TAHO by capturing the sudden enlargement in CSA-UA. Correlation analyses between TAHO and the body mass index (BMI), and between the reduction in CSA-UA and the increase in the neck circumference (NC) with fluid accumulation were performed. Logistic regression analysis was performed for identifying OSA patients based on the behaviors of their CSA-UA changes during leg raising. Shape changes of airway cross-section were also investigated.ResultsFour CSA-UA change patterns after fluid redistribution were identified. Six patients had similar CSA-UA variation behaviors observed in healthy subjects. From the other three change patterns involving 14 patients, a threshold value of CSA-UA 0.63 ± 0.21 cm2 was identified for normal breathing. Data showed a positive correlation between TAHO and BMI (r = 0.681, p = 0.0007), and a negative correlation between the reduction in CSA-UA and the increase in NC (r = − 0.513, p = 0.051) with fluid accumulation. A sigmoid function for the probability of being a OSA patient p = 1/[1 + exp. (4.836 + 3.850 t-8.4 h)] was obtained to effectively separate OSA patients from normal subjects. The upper airway narrowing occurred in anteroposterior, lateral, or both directions, suggesting different tendencies of upper airway collapse in patients. Three types of shape changes in the cross-section of the upper airway, which had different effects on airway resistance, were measured.ConclusionsOur findings prove TAHO hypothesis. The threshold measured while awake for normal breathing can be used clinically as the indicator of hypopnea onset during sleep, and therefore to identify OSA patients under waking condition and design effective personalized treatments for OSA patients. Both shape and size changes in the cross-section of the upper airway affect airway resistance significantly. Shape change in the cross-section of the upper airway can provide key clinical information on the collapse patterns of the upper airway for individuals.

Determining the Thyroid Gland Volume Causing Tracheal Compression: A Semiautomated 3D CT Volumetry Study.

Background and objectives: Increased thyroid gland volume (TV) may bring about tracheal compression, which is one of the causes of respiratory distress. The aim of this study was to investigate the relationship between TV and the severity of tracheal compression independent of patients’ symptoms using semiautomated three-dimensional (3D) volumetry (S3DV) reconstructed from computed tomography (CT) scans. Cut-off TVs leading to different levels of tracheal narrowing were evaluated. Materials and Methods: One hundred sixty-three contrast-enhanced head and neck CT examinations were retrospectively assessed. TVs were measured by S3DV. The degree of tracheal compression was measured at the point where the greatest percent reduction in the cross-sectional area of the trachea adjacent to the thyroid gland was observed. To determine the severity of compression, the tracheal compression ratio (TCR) was defined (TCR = A1 (the narrowest cross-sectional area of trachea)/A2 (the largest cross-sectional area of trachea)). Results: The mean tracheal narrowing was 15% (TCR = 0.85 ± 0.15) in the study population. Patients with more than 15% tracheal compression had significantly higher TV values than those with less than 15% tracheal compression (p < 0.001). In addition, a significant correlation was found between TV and tracheal compression (p < 0.001). Moreover, the receiver operating characteristic (ROC) curve analysis revealed that the cut-off levels for TV that predict a tracheal narrowing of 10%, 20%, 30%, and 40% were 19.75 mL, 21.56 mL, 24.54 mL, and 30.29 mL, respectively (p < 0.05). Conclusions: This study objectively demonstrated that larger thyroid glands cause more severe compression on the trachea. The results may be helpful during the decision-making process for thyroidectomies to be performed due to compression symptoms.

Measurement of Esophagogastric Junction Distensibility May Assist in Selecting Patients for Endoluminal Gastroesophageal Reflux Disease Surgery: Author's Reply.

TO THE EDITOR: We thank the author for his interest in our manuscript.1,2 During the transoral incisionless fundoplication (TIF) procedure, a retractor is anchored at the esophagogastric junction (EGJ) after which tension is applied to advance the EGJ caudally.3,4 Therefore, we agree that lengthening of the EGJ is a substantial mode of action of the TIF procedure. In addition, transmural placement of polypropylene fasteners creates an endoluminal fundoplication through permanent serosa-to-serosa or serosa-to-muscularis fusion with tightening of the distal esophagus, which decreases EGJ diameter and distensibility. 5,6 Therefore, we believe that EGJ distensibility can be an important parameter for evaluation of endoluminal gastroesophageal reflux disease (GERD) surgery like the TIF procedure, although we agree that the immediate decrease in EGJ distensibility after the TIF procedure might be the consequence of postoperative edema.7 It is important to note that consensus is lacking with regard to analysis of parameters obtained from EndoFLIP measurements. According to the most widely accepted approach, EGJ distensibility is assessed based on the narrowest cross sectional area and corresponding intra-bag pressure. Standardized methods to evaluate the change in EGJ length with the EndoFLIP technique are still to be defined. Therefore, we anticipate that development of more extensive biomechanical measures will result in more accurate interpretation of EndoFLIP data. In the present study, we used the EndoFLIP technique in the preoperative diagnostic work-up to predict postoperative outcome. Recent studies highlight that the EndoFLIP technique could be used as an intra-operative quality tool during either anti-reflux or achalasia surgery.8,9 Teitelbaum et al10 described that the EndoFLIP technique is able to guide laparoscopic Heller myotomy and peroral esophageal myotomy to obtain an ideal postoperative EGJ distensibility with regard to both postoperative achalasia and reflux symptoms. In addition, Perretta et al8 provided observational data about the change in EGJ distensibility and diameter during different stages of laparoscopic Nissen fundoplication. In the future, the EndoFLIP method could potentially be used during laparoscopic fundoplication to prevent creation of a hypercompetent valve with associated postoperative symptoms (eg, dysphagia or gas bloating).8 It therefore appears that the EndoFLIP technique has considerable potential as an intra-operative tool. On the other hand, currently available methodologies limit its role with regards to the assessment of EGJ distensibility in the preoperative diagnostic work-up or in post-procedure evaluation of patients undergoing endoluminal GERD surgery like TIF. Additional research is necessary to define the role of the EndoFLIP technique for both the preoperative work-up and tool for intraoperative calibration.

Does Nasal Septal Deviation Affect the Success of Tympanoplasty Surgery?

This paper deals with the investigation of the effects of nasal septal deviation evaluated by acoustic rhinometry (ARM) in the success of tympanoplasty surgery. All patients who underwent tympanoplasty surgery by the same surgeon were reviewed. The patients with nasopharyngeal or nasal masses, polyps, symptoms of allergic rhinitis or rhinosinusitis, or concha bullosa were excluded from the study. Forty patients who underwent tympanoplasty at least one year ago were included in the study. The patients were divided into two groups according to the graft success results. Acoustic rhinometry evaluations of the patients were performed. There were 25 and 15 cases in the intact graft (group A) and re-perforated group (group B), respectively. For the same side of the operated ear, ARM values of group A were 0.47 cm², at the first narrowest cross-sectional area (MCA 1), 0.43 cm² at the second narrowest cross-sectional area (MCA 2), 1.51 cm³ volume at the first 2 cm of the nasal cavity (Vol 1) and 3.33 cm³ volume between the second and fifth cm of the nasal cavity (Vol 2). Acoustic rhinometry values of group B were 0.50 cm², 0.47 cm², 1.60 cm³ and 3.19 cm³ for MCA 1, MCA 2, Vol 1 and Vol 2, respectively. The results of this study showed that nasal septal deviation may not affect the success of tympanoplasty surgery, and septoplasty may not be necessary before ear surgery.

Mechanical Properties of the Esophagus in Eosinophilic Esophagitis

This study aimed to analyze the mechanical properties of the esophagus in eosinophilic esophagitis (EoE) using the functional luminal imaging probe (EndoFLIP; Crospon Medical Devices, Galway, Ireland). Thirty-three EoE patients (22 male; age range, 23-67 years) and 15 controls (6 male; age range, 21-68 years) were included. Subjects were evaluated during endoscopy with the EndoFLIP probe, comprised of a compliant cylindrical bag (maximal diameter 25 mm) with 16 impedance planimetry segments. Stepwise bag distensions from 2 to 40 mL were conducted and the associated intrabag pressure and intraluminal geometry were analyzed. The EndoFLIP clearly displayed the tubular esophageal geometry and detected esophageal narrowing and localized strictures. Stepwise distension progressively opened the esophageal lumen until a distension plateau was reached such that the narrowest cross-sectional area (CSA) of the esophagus maximized despite further increases in intra-bag pressure. The esophageal distensibility (CSA vs pressure) was reduced in EoE patients (P = .02) with the distension plateau of EoE patients substantially lower than that of controls (median: CSA 267 mm(2) vs 438 mm(2); P < .01). Mucosal eosinophil count, age, sex, and current proton pump inhibitor treatment did not predict this limiting caliber of the esophagus (P ≥ 0.20). Esophageal distensibility, defined by the change in the narrowest measurable CSA within the distal esophagus vs intraluminal pressure was significantly reduced in EoE patients compared with controls. Measuring esophageal distensibility may be an important adjunct to the management of EoE, as it is capable of providing an objective means to measure the outcomes of medical or dilation therapy.

Bonding characteristics to dentin walls of class II cavities, in vitro

Objectives: The objective of this study was to test the hypothesis that bond strengths to intact class II cavity wall surfaces are lower than those measured on corresponding flat surfaces isolated by cutting away the rest of the cavity walls. Methods: Class II (MOD) cavities were prepared in extracted human third molars and then divided into two groups: Intact cavity bonding group or flat surface group. All prepared surfaces were acid-etched and bonded with Scotchbond Multi-Purpose Plus adhesive system and restored with Z100 resin composite. After storage in water for 2 days, the teeth were divided mesio-distally into two equal halves. One half was vertically serially sectioned, while the other half was horizontally serially sectioned to yield a series of 0.5 mm thick slabs. Each slab was trimmed into an hour-glass outline with the narrowest cross-sectional area at the region of interest (i.e., axial resin-dentin interface). Results: The mean bond strengths obtained in the cavity bonding group were significantly lower ( p<0.05) than those of the flat bonding group. However, within either group, there were no significant consistent differences among the various regions. Significance: The large flat surfaces used in most laboratory bonding studies may overestimate the bond strengths that can be achieved in complex cavities prepared and restored under clinically relevant conditions.