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PubMed1995

The place of endonasal endoscopy in the relief of middle turbinate sinonasal headache syndrome.

Middle turbinate sinonasal headache syndrome is a rare but not uncommon treatable cause of headache. The true incidence of headache from this cause is unknown. Pneumatization (concha bullosa) or hypertrophy of the middle turbinate can result in it contacting the septum or the lateral nasal wall and may give headaches in the periorbital region. It may occur in the absence of inflammatory sinus disease. The clinical history, nasal endoscopic examination and, coronal CT-scan should point towards the diagnosis and a local anaesthetic challenge test should confirm the diagnosis. Treatment is by relieving the contact point by medical or surgical means. Twenty-one cases of middle turbinate sinonasal headache syndrome refractory to medical treatment are presented with emphasis on the results of endonasal endoscopic surgical treatment.

Adult↗

PubMed1997

[Photocoagulation of the hypertrophic lower turbinates using ND:YAG laser: functional results].

The difficult nasal respiration due to hyperplastic hypertrophy of the turbinates is a broad topic of ongoing interest in otorhinolaryngology. The authors describe a study of 71 patients suffering from hyperplastic hypertrophy of the lower turbinates treated since 1994 by photocoagulation using a ND:YAG laser. The laser treatment was performed on an outpatient basis, under local anesthesia and assisted by the use of an Endo-Video Closed-Circuit Video-Camera. The authors explain the details of the procedure used, emphasize surgical precision and the numerous advantages, the scarcity of intra- and post-operative side effects, the lack of post-operative nasal plugging. In addition, they present the satisfactory functional results achieved. The patients treated were followed up for 6 months prior to surgery and 30 months after laser photocoagulation. After surgery the following tests were performed: fibroscopy, objective symptom evaluation, rhinomanometry, rhinometry, muco-ciliary transport time (MCT), IgAS assay and turbinate biopsy. The low cost of performing this procedure is certainly a plus. The results obtained show a significant and permanent improvement in nasal ventilation and this was both referred by the patients themselves and could be objectively revealed by the ongoing controls. In conclusion, photocoagulation using a ND:YAG laser is well accepted by both physician and patient. It can improve nasal ventilation while respecting the anatomic and functional integrity of the nasal fossae.

Adolescent↗

PubMed1998

Computed axial tomography of the porcine nasal cavity and a morphometric comparison of the nasal turbinates with other visualization techniques.

A non-invasive imaging modality, computed tomography (CT), was used to visualize changes in nasal turbinates of anesthetized pigs over a 12-week observation period (pigs were 14 wk of age at study week 0). Normal, non-infected pigs were compared to pigs with mild challenge-induced atrophic rhinitis (AR) in order to detect subtle differences in morphology. To determine feasibility for time course studies in future experiments, morphometric quantitation at the level of the 2nd premolar (turbinate area ratio or TAR) in cross-section CT images at multiple timepoints was done. Additionally, at study termination, the TAR determined from CT images, magnetic resonance imaging (MRI), and wet tissue (WT), were compared to each other and to the standard subjective measure, visual scoring. There were no statistically significant differences between the control and AR groups at CT imaging dates of 0, 3, 6, 9, or 12 wk (P = 0.182). However, a statistically significant decrease in TAR measurements over time (P = 0.015) was observed in both groups, with lower mean values observed on Weeks 3 and 6 before rebounding to baseline values at study termination. At Week 12 (termination of the study), the TAR measurements derived from CT, MRI, and WT were not statistically different from one another (P = 0.220) and the treatment group-by-method interaction was not significant (P = 0.800). This provided evidence of equivalency of the techniques. Mean values for normal and infected groups were not significantly different based on either TAR imaging methods (P = 0.552) or visual scores (P = 0.088). Thus, the current study demonstrated that CT was an acceptable alternative imaging modality which could be used for quantitation of turbinate changes in snouts of live pigs to provide data comparable to tissue taken at necropsy. Computed tomographic imaging would allow non-invasive tracking of disease or treatment responses within individual animals over time. Morphometric analysis of the TAR was equivalent between the CT, MRI, and WT specimens.

Animals↗

PubMed2002

Immunohistochemical expression of VEGF and VEGF receptors in nasal polyps as compared to normal turbinate mucosa.

The factors involved in the development of chronic inflammation and edema in nasal polyps remain to be clarified. The expression of vascular endothelial growth factor (VEGF) has been described in plasma cells, suggesting that plasma cells may play a major role in the development of edema in nasal polyps through the production of VEGF. We performed immunohistochemical analysis using specific antibodies to VEGF and to the known VEGF receptors, VEGFR-1 and VEGFR-2, on paraffin sections of human nasal polyps ( n=11) and controls of human mucosa of the normal middle turbinates ( n=6). In normal turbinate mucosa, sporadic immunostaining for VEGF was observed throughout the endothelial cells of the small veins and arteries. VEGFR-1 and VEGFR-2 expression was faint in the healthy turbinates. In nasal polyp tissues, strong immunostaining for VEGF was found in the endothelium of blood vessels and in the infiltrating perivascular inflammatory cells. Fibroblasts also stained for VEGF. Strong immunolabeling to VEGFR-1 was evident in the vascular endothelium, whereas weak to moderate VEGFR-1-staining was generally confined to scattered mononuclear round cells. Mononuclear round cells and the endothelium of capillaries revealed immunoreactivity to VEGFR-2. These findings support a role for VEGF and its receptors, VEGFR-1 and VEGFR-2, in the development and perpetuation of edema and angiogenesis in nasal polyps.

Endothelial Growth Factors↗

PubMed1995

Lung function measurement in general practice: a comparison of the Escort spirometer with the Micromed turbine spirometer and the mini-Wright peak flow meter.

It is important that new types of spirometer for widespread clinical use are pragmatically evaluated in primary care. This study compared measurements taken by a new portable Fleisch pneumotachograph spirometer (known as the Escort) with those of the commonly used mini-Wright peak flow meter and the Micromed Pocket turbine spirometer. A pragmatic study was conducted in two phases during routine surgeries at Aldermoor Health Centre, Southampton. Phase I compared the new spirometer with the mini-Wright peak flow meter and Phase 2 compared the new spirometer and the turbine spirometer. One hundred patients aged 5-88 years (56 patients with a history of chronic respiratory complaints and 44 patients without) entered Phase 1, and 100 patients aged 6-82 years (62 patients with a history of chronic respiratory complaints and 38 patients without) entered Phase 2. Each patient contributed only once to each phase, but some entered both phases on separate occasions. Ninety-five percent limits of agreement (mean +/- SD) were wide for all comparisons. Graphical plots revealed trends towards higher Escort values as mean values rose compared with both mini-Wright and turbine readings for peak expiratory flow rate and forced expiratory volume in one second. Possible over-reading of peak expiratory flow rate with the mini-Wright meter at low mean values was also seen. Readings taken with these different types of meter cannot be interchanged with confidence in clinical practice. The clinical significance of the theoretically more accurate measures of lung function produced with the new meter, and indeed of spirometry itself, needs further investigation.

Adolescent↗

PubMed1998

An investigation of the effect of repeated autoclaving on the speed of some dental turbines in general dental practice.

OBJECTIVE: To determine if five types of turbine handpieces could withstand autoclaving in dental practice. METHOD: Five makes of handpieces were used sequentially by four NHS dental practices in the UK. The practitioners oiled and autoclaved the handpieces after every patient use according to the manufacturer's instructions. The number of times the turbine was used and for what procedure was noted. The turbine use was discontinued when the practitioner perceived a significant fall in handpiece performance and the output speed measured. RESULTS: Only one handpiece withstood one year of use in practice with a 1.8% drop in output speed. The other four handpieces had drops in output speeds of 23.5-63.6%. CONCLUSIONS: The results of this survey confirm that some handpieces do not withstand autoclaving. It is also suggested that the tests used in this investigation represent a good assessment of whether a handpiece can withstand autoclaving. It would be useful if data comparable to that described in this paper were available for all handpieces.

Dental High-Speed Equipment↗

PubMed1996

Recovery of respiratory ciliary function after depression by inhalation anaesthetic agents: an in vitro study using nasal turbinate explants.

We have developed a human tissue preparation suitable for measurement of cilia beat frequency derived from nasal turbinates. Cilia beat frequency of turbinate explants from 11 patients did not change significantly over a 10-day observation period while maintained in an incubator, with mean cilia beat frequency of 13.1 (SEM 0.3) Hz to 14.4 (0.2) Hz (ANOVA for repeated measures, P = 0.168). We have used this preparation to investigate recovery of ciliary function after depression by inhalation anaesthetic agents. Eight or nine turbinate explants were exposed to three times the minimum alveolar concentration (MAC) of halothane, enflurane or isoflurane for a period of 1 h and thereafter to a period of air washout. After exposure to the inhalation agent there was a significant reduction in cilia beat frequency with all three agents: halothane 14.3 (0.4) Hz to 9.5 (0.3) Hz; enflurane 13.7 (0.6) Hz to 10.5 (0.5) Hz;isoflurane 15.9 (0.6) Hz to 10.6 (0.3) Hz. Cilia beat frequency returned to values after air washout that were not significantly different from baseline after 90 min of washout of halothane and 60 min of washout of enflurane and isoflurane (repeated measures ANOVA, unpaired t test; P = 0.01 at 60 min and P = 0.31 at 90 min washout for halothane; P = 0.83 at 60 min washout for enflurane; P = 0.26 at 60 min washout for isoflurane).

Adult↗

PubMed1997

Nasal turbinate dislocation caused by nasotracheal intubation.

A case of nasal turbinate dislocation secondary to nasotracheal intubation is presented. Although mild epistaxis had occurred in the days following extubation, the complication was not recognized until after the patient presented with headache and impairment of nasal breathing 6 months later. Endoscopy revealed the dislocation of the middle turbinate into the nasopharynx. Treatment by resection of the dislodged turbinate resulted in relief of symptoms. Physicians should be aware of the possibility of severe nasal damage following even apparently uncomplicated intubation and obtain consultation by an otorhinolaryngologist after epistaxis or obstructed nasal breathing.

Airway Obstruction↗

PubMed2001

Transition to turbulence under low-pressure turbine conditions.

In this paper, the topic of laminar to turbulent flow transition, as applied to the design of gas turbines, is discussed. Transition comes about when a flow becomes sufficiently unstable that the orderly vorticity structure of the laminar layer becomes randomly oriented. Vorticity with a streamwise component leads to rapid growth of eddies of a wide range of sizes and eventually to turbulent flow. Under "natural" transition, infinitesimal disturbances of selected frequencies grow. "Bypass transition" is a term coined to describe a similar process, but one driven by strong external disturbances. Transition proceeds so rapidly that the processes associated with "natural" transition seem to be "bypassed." Because the flow environment in the turbine is disturbed by wakes from upstream airfoils, eddies from combustor flows, jets from film cooling, separation zones on upstream airfoils and steps in the duct walls, transition is of the bypass mode. In this paper, we discuss work that has been done to characterize and model bypass transition, as applied to the turbine environment.

Journal Article↗

PubMed2001

Recent developments in turbine blade internal cooling.

This paper focuses on turbine blade internal cooling. Internal cooling is achieved by passing the coolant through several rib-enhanced serpentine passages inside the blade and extracting the heat from the outside of the blades. Both jet impingement and pin-fin-cooling are also used as a method of internal cooling. In the past number of years there has been considerable progress in turbine blade internal cooling research and this paper is limited to reviewing a few selected publications to reflect recent developments in turbine blade internal cooling.

Journal Article↗

PubMed2001

Effect of Reynolds number, turbulence level and periodic wake flow on heat transfer on low pressure turbine blades.

The development of effective cooling methods is of major importance for the design of new gas turbines blades. The conception of optimal cooling schemes requires a detailed knowledge of the heat transfer processes on the blade's surfaces. The thermal load of turbine blades is predominantly determined by convective heat transfer which is described by the local heat transfer coefficient. Heat transfer is closely related to the boundary layer development along the blade surface and hence depends on various flow conditions and geometrical parameters. Particularly Reynolds number, pressures gradient and turbulence level have great impact on the boundary layer development and the according heat transfer. Therefore, in the present study, the influence of Reynolds number, turbulence intensity, and periodic unsteady inflow on the local heat transfer of a typical low pressure turbine airfoil is experimentally examined in a plane cascade.

Journal Article↗

PubMed2001

Studies on free stream turbulence as related to gas turbine heat transfer. A review of authors' past work and future implications.

A review of the past work done on free stream turbulence (FST) as applied to gas turbine heat transfer and its implications for future studies are presented. It is a comprehensive approach to the results of many individual studies in order to derive the general conclusions that could be inferred from all rather than discussing the results of each individual study. Three experimental and four modeling studies are reviewed. The first study was on prediction of heat transfer for film cooled gas turbine blades. An injection model was devised and used along with a 2-D low Reynolds number k-epsilon model of turbulence for the calculations. Reasonable predictions of heat transfer coefficients were obtained for turbulence intensity levels up to 7%. Following this modeling study a series of experimental studies were undertaken. The objective of these studies was to gain a fundamental understanding of mechanisms through which FST augments the surface heat transfer. Experiments were carried out in the boundary layer and in the free stream downstream of a gas turbine combustor simulator, which produced initial FST levels of 25.7% and large length scales (About 5-10 cm for a boundary layer 4-5 cm thick). This result showed that one possible mechanism through which FST caused an increase in heat transfer is by increasing the number of ejection events. In a number of modeling studies several well-known k-epsilon models were compared for their predictive capability of heat transfer and skin friction coefficients under moderate and high FST. Two data sets, one with moderate levels of FST (about 7%) and one with high levels of FST (about 25%) were used for this purpose. Although the models did fine in their predictions of cases with no FST (baseline cases) they failed one by one as FST levels were increased. Under high FST (25.7% initial intensity) predictions of Stanton number were between 35-100% in error compared to the measured values. Later a new additional production term indicating the interaction between the turbulent kinetic energy (TKE) and mean velocity gradients was introduced into the TKE equation. The predicted results of skin friction coefficient and Stanton number were excellent both in moderate and high FST cases. In fact these model also gave good predictions of TKE profiles whereas earlier unmodified models did not predict the correct TKE profiles even under moderate turbulence intensities. Although this new production term seems to achieve the purpose, it is the authors' belief that it is diffusion term of the TKE equation, which needs to be modified in order to fit the physical events in high FST boundary layer flows. The results of these studies are currently being used to come up with new diffusion model for the TKE equation.

Journal Article↗

PubMed2004

Perception and annoyance due to wind turbine noise--a dose-response relationship.

Installed global wind power increased by 26% during 2003, with U.S and Europe accounting for 90% of the cumulative capacity. Little is known about wind turbines' impact on people living in their vicinity. The aims of this study were to evaluate the prevalence of annoyance due to wind turbine noise and to study dose-response relationships. Interrelationships between noise annoyance and sound characteristics, as well as the influence of subjective variables such as attitude and noise sensitivity, were also assessed. A cross-sectional study was performed in Sweden in 2000. Responses were obtained through questionnaires (n = 351; response rate 68.4%), and doses were calculated as A-weighted sound pressure levels for each respondent. A statistically significant dose-response relationship was found, showing higher proportion of people reporting perception and annoyance than expected from the present dose-response relationships for transportation noise. The unexpected high proportion of annoyance could be due to visual interference, influencing noise annoyance, as well as the presence of intrusive sound characteristics. The respondents' attitude to the visual impact of wind turbines on the landscape scenery was found to influence noise annoyance.

Adolescent↗

PubMed1990

Measuring peak expiratory flow in general practice: comparison of mini Wright peak flow meter and turbine spirometer.

OBJECTIVE: To compare measurements of the peak expiratory flow rate taken by the mini Wright peak flow meter and the turbine spirometer. DESIGN: Pragmatic study with randomised order of use of recording instruments. Phase 1 compared a peak expiratory flow type expiration recorded by the mini Wright peak flow meter with an expiration to forced vital capacity recorded by the turbine spirometer. Phase 2 compared peak expiratory flow type expirations recorded by both meters. Reproducibility was assessed separately. SETTING: Routine surgeries at Aldermoor Health Centre, Southampton. SUBJECTS: 212 Patients aged 4 to 78 presenting with asthma or obstructive airways disease. Each patient contributed only once to each phase (105 in phase 1, 107 in phase 2), but some entered both phases on separate occasions. Reproducibility was tested on a further 31 patients. MAIN OUTCOME MEASURE: 95% Limits of agreement between measurements on the two meters. RESULTS: 208 (98%) Of the readings taken by the mini Wright meter were higher than the corresponding readings taken by the turbine spirometer, but the 95% limits of agreement (mean difference (2 SD] were wide (1 to 173 l/min). Differences due to errors in reproducibility were not sufficient to predict this level of disagreement. Analysis by age, sex, order of use, and the type of expiration did not detect any significant differences. CONCLUSIONS: The two methods of measuring peak expiratory flow rate were not comparable. The mini Wright meter is likely to remain the preferred instrument in general practice.

Adolescent↗

PubMed2005

Multipass open-path Fourier-transform infrared measurements for nonintrusive monitoring of gas turbine exhaust composition.

The detection limits for NO and NO2 in turbine exhausts by nonintrusive monitoring have to be improved. Multipass mode Fourier-transform infrared (FTIR) absorption spectrometry and use of a White mirror system were found from a sensitivity study with spectra simulations in the mid-infrared to be essential for the retrieval of NO2 abundances. A new White mirror system with a parallel infrared beam was developed and tested successfully with a commercial FTIR spectrometer in different turbine test beds. The minimum detection limits for a typical turbine plume of 50 cm in diameter are approximately 6 parts per million (ppm) for NO and 9 ppm for NO2 (as well 100 ppm for CO2 and 4 ppm for CO).

Algorithms↗

PubMed1989

[Analysing noise levels in dental environment. Air turbine sound response to various physical factors].

Dental Air Turbine sound depends on the mechanical performance such as rotation and it is impossible to neglect connections of the sound with fluid mechanics and acoustics. Turbine sound must be considered from the standpoint of the sound pressure level and frequency component. In this study, the sound samples was measured and analysed in octave band spectrum. Turbine sound has three resonance bands of the frequency with the range from 0 to 1,600 Hz and the resonance band increased as air pressure increased. The frequency of the second resonance band decreased as the cutting load and cutting point diameter increased. Damping of the second resonance band frequency shifted downward by polishing point.

Dental High-Speed Equipment↗

PubMed1976

[Noise risk due to dental turbines].

Sound level measurements and frequency analyses were carried out on dental turbines in order to assess the risk of hearing defects due to the noise caused by such turbines. The measured values were related to other factors (exposure time, noise pauses) and the overall situation was evaluated. A major leasion of the auditory organ due to the noise caused by dental turbines seems unlikely.

Dental High-Speed Equipment↗

PubMedDate not supplied

A testing machine for dental air-turbine handpiece characteristics: free-running speed, stall torque, bearing resistance.

The measurement of performance characteristics of dental air turbine handpieces is of interest with respect to product comparisons, standards specifications and monitoring of bearing longevity in clinical service. Previously, however, bulky and expensive laboratory equipment was required. A portable test machine is described for determining three key characteristics of dental air-turbine handpieces: free-running speed, stall torque and bearing resistance. It relies on a special circuit design for performing a hardware integration of a force signal with respect to rotational position, independent of the rate at which the turbine is allowed to turn during both stall torque and bearing resistance measurements. Free-running speed without the introduction of any imbalance can be readily monitored. From the essential linear relationship between torque and speed, dynamic torque and, hence, power, can then be calculated. In order for these measurements to be performed routinely with the necessary precision of location on the test stage, a detailed procedure for ensuring proper gripping of the handpiece is described. The machine may be used to verify performance claims, standard compliance checks should this be established as appropriate, monitor deterioration with time and usage in the clinical environment and for laboratory investigation of design development.

Air↗