Expandable metallic stent placement in patients with benign esophageal strictures: results of long-term follow-up

Prosthetic mandibular advancement (PMA) was applied to nine patients with obstructive sleep apnea syndrome (OSAS) and its therapeutic usefulness, mechanism of action, and clinical indication were discussed based on polysomnographic findings and serial examination of upper airway before and during PMA treatment. Apnea hypopnea index significantly decreased during PMA treatment compared with the value before treatment (P < 0.01) and the rate of the treatment responder counted 78.1%. Cephalometric variables indicated forward and inferior advancement of mandible in our subjects. Magnetic resonance imaging of the upper airway during sleep revealed a marked improvement of velophanryngeal obstruction in most subjects. In addition, intraesophageal negative pressure during sleep decreased significantly. Our results confirmed the high therapeutic efficacy of PMA for OSAS and indicated forward advancement of the mandible and decrease of negative pressure loading on upper airway with PMA might suppress velopharyngeal collapse. Thus, PMA was regarded as one of the treatments of choice for OSAS occurring based on with velopharyngeal narrowing.     

Relationship between velopharyngeal dimensions and palatal EMG during progressive hypercapnia

To examine the contribution of specific palatal muscles to velopharyngeal dimensions, we recorded electromyographic (EMG) activity in the levator veli palatini, the tensor veli palatini, and the palatoglossus while examining the velopharynx (VP) with videoendoscopy in eight awake normal adults. Simultaneous display of VP images and airflow provided precise timing of events. Video images and EMG signals were recorded during progressive hypercapnia. Every tenth breath was analyzed. For each selected breath, VP area, anteroposterior and lateral diameters, and EMG activity were determined at five points: beginning, middle, and end of inspiration and middle and end of expiration. VP measurements changed significantly during the respiratory cycle. Although maximum area was measured at end inspiration or middle expiration and minimum area at the beginning or end of the breath, respiratory-related changes in VP measurements and EMG activity were characterized by substantial inter- and intrasubject variability. This variability is similar to velopharyngeal behavior during nonrespiratory tasks and suggests that upper airway patency is determined by multiple factors.     

Digital fluoroscopy before and after laser uvulopalatopharyngoplasty in obstructive sleep apnea. Importance of pharyngeal collapsibility and hyoid bone position

PURPOSE: To study the changes in pharyngeal behavior after laser uvulopalatopharyhgoplasty (LUPPP). MATERIAL AND METHODS: The dynamic changes in the upper airway size were evaluated with digital fluoroscopy in 24 patients with obstructive sleep apnea (OSA) before and after LUPPP and in 16 normal controls, while they were awake and breathing normally. Cephalometric measurements were also made. The patients were classified into the categories of good and poor responders by means of a static-charge-sensitive bed. RESULTS: Following LUPPP, collapsibility at the velopharyngeal level was within the normal range m 15 of 17 good responders, but only in 2 of 7 poor responders (p = 0.0086). The minimum airway size at the same level showed a similar trend. In 3 of 7 poor responders the hyoid bone was positioned more caudally than in the good responders (p = 0.017). CONCLUSION: Digital fluoroscopy provides information on the change in upper airway behavior after LUPPP.     

Aerodynamic and acoustic characteristics of a speaker with turbulent nasal emission: a case report

Aerodynamic and acoustic characteristics were determined from the speech of an adult female with mild mental retardation and severe velopharyngeal inadequacy. The speaker's productions of /s/ were characterized by consistent nasal grimacing and turbulent air emission. Aerodynamic assessment estimated the size of the velopharyngeal orifice to exceed 200 mm2 during plosive production. Nasal cross-sectional area was estimated to be 35 mm2 during quiet breathing. Nasometric evaluation indicated nasalance of 63% associated with the "Zoo" passage. Acoustic analysis of the separately recorded oral and nasal speech signals indicated spectral energies in the region of approximately 2.5 to 7.0 kHz associated with nasal emission during /s/ production. The occurrence of these frequencies suggested an acoustic/perceptual function of the nasal grimace. Pressure-flow evidence also suggested that the nasal grimace, perhaps with lingual assistance, functioned to enhance speech aerodynamics.     

Mitral valve area in combined mitral stenosis and regurgitation

Eight patients with mixed mitral stenosis and regurgitation underwent hemodynamic and angiographic study prior to mitral valve replacement. The stenotic orifice of the mitral valve was calculated employing the total left ventricular stroke volume by cineangiography as the numerator of the Gorlin Formula. Excellent agreement with the measured orifice of the mitral valve was obtained using a value of 37.9 (0.85 X 44.5) for the constant in the Gorlin formula as recommended by Cohen and Gorlin. Recalculation of this constant independently by our data yielded a value that was almost identical. Regurgitant flows and orifice sizes were calculated for each patient using the same constant as for calculation of the stenotic orifices.     

Upper airway assessment: radiographic and other imaging techniques

Upper airway imaging is a powerful technique to study the mechanisms underlying the pathogenesis and biomechanics of sleep apnea and the mechanisms underlying the efficacy of therapeutic interventions in patients with sleep disordered breathing. The primary upper airway imaging modalities include nasopharyngoscopy, cephalometrics, CT scanning, and MR imaging. Imaging studies using these modalities have provided important insights into the static and dynamic structure and function of the upper airway and surrounding soft-tissue structures during wakefulness and sleep. Such imaging studies have highlighted the importance of the lateral pharyngeal walls in mediating upper airway caliber. These imaging modalities have also been used to study the effect of respiration, weight loss, mandibular repositioning devices, and upper airway surgery on the upper airway. Three-dimensional reconstruction of the airway and surrounding soft-tissue structures can be performed with MR imaging and CT scanning. Clinical indications for upper airway imaging are evolving such that imaging studies should be considered in patients with sleep apnea who are being treated with dental appliances or upper airway surgery.     

Predator-induced nest site preference: safe nests allow courtship in sticklebacks

The sphincter pharyngoplasty is a surgical procedure designed to correct velopharyngeal dysfunction. Its advocates cite the theoretical advantage of its induction of dynamic activity of the neovelopharyngeal port, but this dynamic activity has yet to be quantitatively demonstrated in the literature. The purpose of this study was to quantify postoperative velopharyngeal dynamism and to document the results of intervention outcome on sphincteric excursion measurements from minimal-to-maximal orifice closure. We conducted a 7-year retrospective review of speech videofluoroscopy evaluations in patients who had undergone sphincter pharyngoplasty in our center. Between 1989 and 1994, there were 58 patients so treated for postpalatoplasty velopharyngeal dysfunction by two surgeons using the same operative technique. Patients for whom sphincter pharyngoplasty was recommended fulfilled both of the following criteria: (1) velopharyngeal dysfunction caused by an anatomic, myoneural, or combined deficiency of the velopharyngeal sphincter that would not be expected to be managed by speech therapy alone, and (2) preoperative videonasendoscopy and speech videofluoroscopic studies that demonstrated large-gap coronal, circular, or bow-tie closure patterns or velopharyngeal hypodynamism. Of the original 58 patients, 24 underwent postoperative speech videofluoroscopic evaluations with basal views. Of these, 20 of the evaluations (83 percent) were of adequate quality to be included in a research study. Still images showing maximum and minimum excursion of the sphincter in basal view were obtained. To test for observer reliability, the speech videofluoroscopic studies were randomized and presented for measurement to the same individual on two occasions, each session separated by a 1-month time interval. Topographic imaging software was used to obtain maximum and minimum measurements to within 0.1 mm. Partitioning the variance of the data showed that measurement variability was a very small portion of the total, and that difference between the minimum and maximum values was the largest source of variability. Of the total variability in the data, 64.0 percent originated in the minimum/maximum difference, 34.3 percent came from patient variability, and only 1.7 percent resulted from original or repeat measurements. The patient variability may be exaggerated because of variability in the scale of measurement. Results of this study indicate a quantifiable and statistically significant difference in maximum-to-minimum excursion of sphincteric closure. Sphincter pharyngoplasty appears to be dynamic in the majority of cases.     

Fluid Dynamics of Vortex Formation in Tundish Operations: Physical Modelling

The present study focuses on the fluid dynamics of vortex formation in tundish operations using a physical water analogue model and Particle Image Velocimetry (PIV) measurements. The aim is to get fundamental knowledge of the nature of vortex formation that clearly represents this flow phenomenon. The results indicate that vortex formation is directly related to the highly turbulent flows present in the tundish. Great changes of velocity fields during short times and large distances between the upper edge of the dam and the free surface of the bath enhance the formation of vortex flows. Therefore, increasing tundish capacity does not guarantee steel cleanliness through long residence times if the dam height is not adjusted to the new level of liquid in the tundish.     

Upper airway imaging

Upper airway imaging is a powerful technique to study the mechanisms underlying the pathogenesis, biomechanics, and efficacy of treatment options in patients with obstructive sleep apnea. Imaging studies have provided significant insight into the static and dynamic structure, and function of the upper airway and surrounding soft-tissue structure during wakefulness and sleep. Upper airway imaging modalities primarily include nasopharyngoscopy, cephalometrics, computed tomography (CT), and magnetic resonance (MR) scanning. These imaging modalities have been used to study the effect of respiration, weight loss, dental appliances, and upper airway surgery on the upper airway. MR imaging and CT have allowed quantification of the airway and surrounding soft-tissue structures in three dimensions. Clinical indications for upper airway imaging are evolving for patients being treated with dental appliances and upper airway surgery.     

Occurrence and trends in ski injuries in Norway

OBJECTIVE: The objective of this study was to determine the influence of velopharyngeal (VP) inadequacy on respiratory speech compensations. DESIGN: The pressure-flow technique was used to measure pressure, airflow, and timing variables associated with VP closure during the production of the initial plosive consonant /p/ in a series of the utterance "papa." SETTING: The study was conducted in the speech and breathing laboratory of the UNC Craniofacial Center. PARTICIPANTS: Eighty-two subjects with cleft lip and/or palate were assessed. The subjects were divided into two groups, those with adequate VP closure (VP size <.010 cm2) and those with inadequate VP closure (VP size >0.10 cm2). The adequate group was comprised of 62 subjects, and 20 subjects were categorized as inadequate. RESULTS: Peak intraoral pressure decreased in the inadequate group, but the difference was not significant. Nasal airflow increased (p < .01), but duration of the pressure pulse was the same for both groups. The area under the pressure curve decreased for the inadequate group (p = .04). CONCLUSION: These data contrast with previously reported published data using /p/ in the utterance "hamper." This suggests that phonetic context influences the compensatory response to velopharyngeal inadequacy. Additionally, while the findings are somewhat similar to studies that involved noncleft subjects whose oral airway was suddenly vented during the production of /p/, there is enough difference to suggest that learning also affects the compensatory outcome.     

A method of studying adaptive changes of the oropharynx to variation in mandibular position in patients with obstructive sleep apnoea

The aim of this study was to develop a method of studying the effects of mandibular advancement on oropharyngeal airway dimensions in the sagittal plane in conscious, supine patients. Six white, dentate, male patients with proven obstructive sleep apnoea had sagittal fluoroscopic recordings taken in the resting supine position. Images were recorded at four frames per second as the mandible was advanced with the teeth in contact to maximum protrusion and then opened. Software in the fluoroscopic imaging system permitted measurement of the change in mandibular position together with oropharyngeal airway dimensions expressed as the narrowest dimension observable in the post-palatal and post-lingual sites. Plotting of airway dimensions during mandibular advancement enabled estimation of the degree of protrusion associated with maximal airway benefits. Progressive mandibular advancement produced variable adaptive changes in the post-palatal and post-lingual regions of the oropharynx. The amount of airway opening appeared to be related to the horizontal and vertical relationships of the face and to the dimensions of the soft palate. The changes in post-palatal and post-lingual airway dimensions were not always identical, despite the observation that both tongue and soft palate were seen to move in unison, with close contact being maintained between the two structures. Jaw opening resulted in synchronous posterior movement of both tongue and soft palate, with consequent narrowing of oropharyngeal airspace. Fluoroscopy is a simple method of assessing upper airway changes with mandibular advancement in the conscious patient. The technique should facilitate the selection of subjects for whom mandibular advancement would seem advantageous. The nature of the adaptive response is dependent on individual structural variation. It is suggested that, where artificial mandibular advancement with dental devices is considered beneficial, jaw opening should be kept to a minimum.     

Quality of corneal donor tissue in the greater-than-75-year age group

Impaired nasal breathing has been reported to cause changes in human head posture. The aim of this study was to assess whether there was any relationship between nasorespiratory function and variables of head posture in 58 young adults. The pressure flow technique was used to measure airflow rate and oral/nasal pressure and to calculate the smallest cross-sectional area of the nasal airway. A natural head position roentgenocephalogram was used to measure the craniovertical angulation (NSL/VER), craniocervical angulation (NSL/OPT), and cervical spine inclination (OPT/HOR). The results showed a trend toward enlarged craniocervical angulation and forward inclination of the cervical spine in subjects with a relatively large nasal cross-sectional area. Though the general opinion on the effects of reduced upper airway size on head posture is opposite, these results are an experimental confirmation of the theoretically expected mechanism that leads to increased head extension in obstructed subjects.     

Immune response to a single bout of exercise in young and elderly subjects

Mandibular advancement splints are successful in managing obstructive sleep apnoea (OSA) in selected subjects. For these to be effective, some improvement in the dimensions of the oropharyngeal airway must occur. Twenty subjects with proven obstructive sleep apnoea were examined using lateral cephalometric radiography and a fluoroscopic technique. Cephalograms were analysed, and assessed for both skeletal and soft tissue abnormalities known to be present in OSA subjects. On the basis of these, a prediction was made as to whether the subject's oropharyngeal airway would increase during mandibular protrusion. From the fluoroscopic sequences, the narrowest antero-posterior dimensions of the post-palatal and post-lingual airways were recorded as the mandible moved from the intercuspal position into maximal protrusion. The changes in airway size were noted and these were compared with the predictions made from the static films. In nine subjects, fluoroscopy indicated that the airway opened well during mandibular protrusion, seven did not improve and in four the changes were minimal. Post-palatally the mean airway increase was 2.6 mm, whilst behind the tongue a mean improvement of 3.1 mm was seen. In all but two instances, the cephalometric prediction agreed exactly with the outcome demonstrated by fluoroscopy. All subjects whose airways clearly increased were correctly identified by the cephalogram alone. Cephalometric features associated with a good airway response to protrusion were a reduced lower facial height, low maxillomandibular planes angle and a high hyoid position, accompanied by a normal anteroposterior relationship of the jaws, relatively normal mandibular body length and soft palate area. The more abnormal the skeletal and soft tissue dimensions, the poorer the prognosis. Thus, whilst a single radiograph could indicate whether a positive mandibular response to protrusion could be expected, where doubt existed, a fluoroscopic analysis could provide a useful adjunct to diagnosis.     

Identification and semi-quantitation of Ostertagia ostertagi eggs by enzymatic amplification of ITS-1 sequences

The forced oscillation technique (FOT) is a non-invasive method which may be suitable for assessing upper airway obstruction in obstructive sleep apnea/hypopnea syndrome (OSAS) patients. The aim of this study was to determine in vitro if FOT can provide an early detection index of total or partial upper airway occlusion. A respiratory system analog was developed which includes an upper airway analog that allows simulation of upper airway collapse (thus mimicking the situation in patients with OSAS). We simulated different degrees of upper airway obstructions ranging from 0 (unobstructed airways) to 1 (total occlusion). Furthermore, we imitated the collapsible upper airway wall by means of elastic membranes with ten different wall compliances ranging from 3.3 x 10(-4) to 1 1/mbar. For the two stiffest rubber membranes (Cwall = 0.01 and 3.3 x 10(-4) l/mbar) the absolute value of the impedance (?Z?) showed a marked increase for obstructions greater than 0.6. For the two membranes with the highest wall compliances (Cwall = 0.03 and 1 1/mbar) obstructions with an increase in ?Z? could not be detected before the obstruction reached 0.8. For degrees of obstruction less than 0.6 the phase angle of collapsible membranes with low compliance (stiff airway wall) were about 1.5pi which significantly differed from phase angles of 1.77pi measured in membranes with high compliance (elastic airway wall); p < 0.01. We hypothesized that stiffness of upper airway walls corresponds with their muscle tone, i.e., stiff airway walls are related with high muscle tone and vice versa. Thus, a decrease in upper airway muscle activity would cause an increase of upper airway wall elasticity that enables upper airway collapse. As a consequence the phase angle phi could be expected to change from values characterizing stiff membranes to values characterizing more elastic membranes which could be used as early indicator for obstructive respiratory events. We have frequently observed such changes in morphology of phi(t) data obtained from patients with OSAS.     

Peripheral noxious stimulation induces CREM expression in dorsal horn: involvement of glutamate

Thermal washout curves have been proposed as noninvasive tools for analysing lower airway dimensions and pulmonary blood flow, but how upper airway heat transfer affects these washout curves is unclear. The present study was designed to compare extrathoracic and tracheobronchial contributions to thermal washout curves. Respiratory frequency, air ambient temperature, and body core temperature (tc) were varied in six male subjects before and after immersion in cold (1.1 degrees C) water for up to 2 h under three conditions: 1) control: ambient temperature (tamb) = 25 degrees C, rectal temperature change (delta tre) = 0 degrees C; 2) pre-immersion: tamb = 4 degrees C, delta tre = 0 degrees C; and 3) post-immersion: tamb = 25 degrees C, delta tre = -0.7 degrees C. Both peak expiratory nasal (tpn) and oral (tpo) airstream temperatures were measured. Each subject was tested twice. Expiratory tpo was generally higher than tpn in all conditions. Increasing breathing rates lowered tpn and tpo in the control and cold air environments. Orifice temperatures, which are presumed to reflect upper airway blood temperatures, correlated with both tpn and tpo. Lowering tc had no effect on washout curves during quiet breathing and affected only tpn during rapid breathing. The results suggest that while tracheobronchial conditions may contribute to thermal washout curves, extrathoracic conditions predominate. Strong correlations between orifice temperatures, peak expiratory nasal temperatures and peak expiratory oral temperature demonstrate the dominant role of upper airway heat exchange in determining thermal washout curves.     

Modeling Nonspherical Particles Using Multisphere Discrete Elements

In this paper axisymmetrical particles are modeled as multisphere discrete elements using a method in which particles are represented by overlapping spheres, fixed rigidly with respect to a local coordinate system. Contact detection is sphere-based and the resultant forces are transformed to the particle centroid to calculate the particle motion using standard discrete element method conventions. The multisphere method was used to model discharge of ellipse-shaped particles through an orifice in a flat-bottomed hopper and the simulations compared with physical experiments at the same scale. There was good agreement between the flow behavior of the simulated and physical particle assemblies for all orifice sizes. The rate of discharge and the vertical velocity profiles in the region of converging flow determined for the simulated and physical flows were in close agreement for flow from the larger orifices. A similar relationship between frequency of arch formation, particle mean diameter, and orifice diameter as for spheres was observed.     

Periodic Oscillation Caused by a Flow over a Vertical Drop Pool

The flow patterns of various dropping flows were investigated and classified experimentally for subcritical approach flows passing a vertical drop pool. A wave gauge was used to measure the free surface fluctuations in the pool. A flow visualization technique was employed to reveal the flow structure of the dropping flows qualitatively. It was discovered that, under certain conditions, the dropping flow forms a switching jet that oscillates up and down periodically and impinges on the bed and the downstream pool wall alternately. The switching jet switches between an impinging jet (a napped flow) and a sliding jet (a skimming flow), causing it to oscillate periodically with a unique period. The primary frequency of the periodic oscillation was determined by applying spectral analysis to the time series of the gauge measurements. Since a large number of air bubbles was entrained in the oscillatory flow, particle image velocimetry, and bubble image velocimetry were used for quantitative velocity determination in the liquid region and the aerated region, respectively. The mechanism causing the periodic oscillation in the pool was elucidated, and variables affecting the oscillation frequency were identified. An empirical relation between a weighted Strouhal number and a grouped dimensionless parameter was proposed to predict the primary frequency of the periodic oscillatory flow.     

Effect of mandibular and tongue protrusion on upper airway size during wakefulness

Oral appliances for the treatment of obstructive sleep apnea (OSA) produce either mandibular or tongue protrusion, and are thought to enlarge the upper airway (UA). We used videoendoscopy to measure UA cross-sectional area (CSA) and shape in the hypopharynx, oropharynx, and velopharynx during various stages of active mandibular and tongue protrusion during wakefulness in 10 patients with OSA and nine control subjects. Measurements were made in the supine position at end-tidal expiration, and were normalized to the CSA in the normal bite position. Airway shape was expressed as the anteroposterior/lateral (AP/L) diameter ratio. There were no differences between OSA patients and controls in the effects of mandibular and tongue protrusion on UA caliber. Both mandibular and tongue protrusion increased CSA in the hypopharynx and oropharynx (p < 0.001), whereas only tongue protrusion increased CSA in the velopharynx (p < 0.001). Tongue protrusion caused a greater increase in oropharyngeal and velopharyngeal CSA than did mandibular protrusion (p < 0.05). Mandibular protrusion caused a greater increase in CSA in the hypopharynx than in the oropharynx or velopharynx (p < 0.05). Obese patients had a larger relative increase in oropharyngeal CSA with mandibular and tongue protrusion than did subjects of normal weight. Tongue protrusion increased the AP/L diameter ratio in the oropharynx and velopharynx (p < 0.001), and mandibular protrusion did so to a lesser extent in the oropharynx (p < 0.01), resulting in a more circular airway shape. We conclude that mandibular and tongue protrusion increase the CSA and alter the shape of the UA during wakefulness.     

Mechanism of dynamic regurgitant orifice area variation in functional mitral regurgitation: physiologic insights from the proximal flow convergence technique

OBJECTIVES: We used the Doppler proximal flow convergence technique as a physiologic tool to explore the effects of the time courses of mitral annular area and transmitral pressure on dynamic changes in regurgitant orifice area. BACKGROUND: In functional mitral regurgitation (MR), regurgitant flow rate and orifice area display a unique pattern, with peaks in early and late systole and a midsystolic decrease. Phasic changes in both mitral annular area and the transmitral pressure acting to close the leaflets, which equals left ventricular-left atrial pressure, have been proposed to explain this dynamic pattern. METHODS: In 30 patients with functional MR, regurgitant orifice area was obtained as flow (from M-mode proximal flow convergence traces) divided by orifice velocity (v) from the continuous wave Doppler trace of MR, transmitral pressure as 4v(2), and mitral annular area from two apical diameters. RESULTS: All patients had midsystolic decreases in regurgitant orifice area that mirrored increases in transmitral pressure, while mitral annular area changed more gradually. By stepwise multiple regression analysis, both mitral annular area and transmitral pressure significantly affected regurgitant orifice area; however, transmitral pressure made a stronger contribution (r2 = 0.441) than mitral annular area (added r2 = 0.008). Similarly, the rate of change of regurgitant orifice area more strongly related to that of transmitral pressure (r2 = 0.638) than to that of mitral annular area (added r2 = 0.003). A similar regurgitant orifice area time course was observed in four patients with fixed mitral annuli due to Carpentier ring insertion. CONCLUSIONS: In summary, the time course and rate of change of regurgitant orifice area in patients with functional MR are predominantly determined by dynamic changes in the transmitral pressure acting to close the valve. Thus, although mitral annular area helps determine the potential for MR, transmitral pressure appears important in driving the leaflets toward closure, and would be of value to consider in interventions aimed at reducing the severity of MR.     

Airway resistance and work of breathing in tracheostomy tubes

Recommendations for sizing of tracheostomy tubes are generally based on anatomic considerations with the largest fitting tube most commonly placed. Once in the tracheostomy site, the tube assumes the new role of the upper airway. Consideration of the airway resistance of each tracheostomy tube and change in work of breathing are important in maintaining the respiratory system homeostasis. The airflow dynamics of neonatal, pediatric, and adult tracheostomy tubes were studied. Flow rates were plotted against change in pressure for inspiratory and expiratory flows and resistances for each tube were calculated. The expiratory resistances were larger for the neonatal tubes and pediatric tubes 0 and 00, while inspiratory resistances were the limiting factor in the adult tubes and the larger pediatric tubes. Comparison of calculated resistances of the tracheostomy tubes was made with known physiologic airway resistances. Adult tubes 8 and 10 most closely simulated the upper airway resistance of adults and neonatal tube 0 appeared most appropriate for the newborn. Work of breathing was determined for each tracheostomy tube. Increasing tube diameter as well as decreasing tidal volume and respiratory rate decreased the amount of work required to maintain a given flow.