Biomedical subjects

O Hilberg

Publications and source records attributed to O Hilberg.

At least 19 recordsLinked to original sources

PubMed2002

Flextube reflectometry for level diagnosis in patients with obstructive sleep apnoea and snoring.

The aim of this study was to use sound reflections in a flexible tube (flextube reflectometry) for identifying the predominant obstructive level of the upper airway in a series of patients referred to a sleep clinic. We also wished to study the relationship between the number of flextube narrowings per hour recording and the RDI (respiratory disturbance index = apnoeas and hypopneas per hour recording) by ResMed AutoSet (AS), which is a device based on nasal pressure variations. We performed sleep studies on 54 patients referred for snoring or OSA; 1) at home with AS; 2) in hospital using flextube reflectometry and AS simultaneously. The predominant obstructive level of the upper airway was retropalatal in 15 of the patients and retrolingual in 25 of the patients determined by flextube reflectometry. In 14 there was no predominant level of narrowing. We found a statistically significant correlation between the number of flextube narrowings per hour recording and the RDIs by the AS (Spearman's correlation coefficient r = 0.62, p < 0.001, n = 54). Flextube reflectometry may provide useful information regarding the level of obstructive predominance during obstructive events. The method also determines the frequency of respiratory disturbances and records snoring sound.

Adult↗

PubMed2002

Flextube reflectometry and pressure-recordings for level diagnosis in obstructive sleep apnoea.

The objective of this study was to compare sound reflections in a flexible tube (flextube reflectometry) with pressure-catheter recordings (ApneaGraph) for identifying the predominant obstructive level of the upper airway during sleep. Seventeen males with suspected obstructive sleep apnoea syndrome (OSAS) were included in the study. The mean (standard deviation = SD) number of flextube narrowings per hour recording was 50.2 (20.4) and the mean (SD) RDI (respiratory disturbance index = apnoeas and hypopnoeas per hour recording) determined by the ApneaGraph was 45.7 (20.2). The mean difference (SD) between the number of flextube narrowings per hour recording and the RDIs determined by the ApneaGraph was not statistically significantly different from 0. There was no statistically significant correlation between the percentage of retropalatal narrowing of the total narrowing (retropalatal and retrolingual narrowing) measured by flextube reflectometry and the percentage of retropalatal ("upper") obstructive apnoeas and hypopnoeas of the total number ("upper", "intermediate" and "lower") measured by ApneaGraph (Spearman's correlation coefficient r = 0.24, p = 0.36, N = 17). In conclusion diverging results were found in flextube reflectometry studies and pressure-recordings performed on different nights regarding the level distribution of obstructions during sleep. Possible explanations of this discrepancy are discussed.

Acoustics↗

PubMed2001

Flextube reflectometry for localization of upper airway narrowing--a preliminary study in models and awake subjects.

The aim of this study was to examine an acoustic reflection method using a flexible tube for identifying the obstructive site of the upper airway in snorers and patients with obstructive sleep apnoea (OSA). As a preliminary study it was performed n models and subjects in the awake state. Flextube narrowing was produced in a model of the nose and pharynx and three blinded observers assessed the obstructive level. The correlation between pharyngeal narrowing assessed by endoscopy and by acoustic measurement during Müller manoeuvres was also examined in 10 OSA patients and 11 healthy non-snoring, adults. Three blinded observers dentified the level of 176 of 180 random cases of flextube narrowing in a polycarbonate model correctly The level of narrowing was always correctly evaluated within 1.9 mm. Pharyngeal area decrease was measured by the flextube method during the Müller manoeuvre but it was not closely related to the findings by endoscopy. In conclusion the flextube reflectometry method was able to demonstrate narrowng in a model of the nose and pharynx in a precise way. Narrowing was also observed during Müller manoeuvres. Flextube reflectometry may be a promising method to detect upper airway narrowing but further evaluation during sleep is required.

Adult↗

PubMed2001

Flextube reflectometry for determination of sites of upper airway narrowing in sleeping obstructive sleep apnoea patients.

The aim of this study was to examine a new technique based on sound reflections in a flexible tube for identifying obstructive sites of the upper airway during sleep. There was no significant difference between two nights in seven obstructive sleep apnoea (OSA) patients regarding the level distribution of pharyngeal narrowings, when the pharynx was divided into two segments (retropalatal and retrolingual). We also compared the level distribution determined by magnetic resonance imaging (MRI) with the level distribution found by flextube reflectometry in seven OSA patients. There was no significant difference between flextube and MRI level distributions during obstructive events, but due to few subjects the power of the test was limited. We found a statistically significant correlation between the number of flextube narrowings per hour of sleep and the number of obstructive apnoeas and hypopnoeas per hour of sleep determined by polysomnography (PSG) in 21 subjects (Spearman's correlation coefficient r = 0.79, P < 0.001). In conclusion, the flextube reflectometry system seems to be useful for level diagnosis in OSA before and after treatment.

Adult↗

PubMed2001

The occurrence of sinusitis in HIV-infected patients with fever.

Sinusitis is commonly occurring in patients infected with Human Immunodeficiency Virus I (HIV), but the occurrence and etiology have not been established. The purpose of this study was prospectively to determine the occurrence, site and type of paranasal sinus abnormalities seen on MRI in HIV-infected patients with fever, to relate the abnormalities to clinical and immunological parameters, and to determine the microbiological agents found in the sinus aspirates. MRI was performed in 54 HIV-infected patients with 70 evaluable episodes of fever. Patients receiving antibiotics were excluded. Bactrim was permitted, when given as prophylaxis of Pneumocystis carinii pneumonia. If abnormalities were found on MRI, sinus aspiration was performed and the aspirate investigated. MRI abnormalities were found in 54.3% of the patients with a significantly higher occurrence of pathological changes in AIDS patients compared with HIV-infected without AIDS. In approximately 2/3 of the aspirates a probable, etiologic agent was found. However, 1/3 of these agents were atypical such as cytomegalovirus and mycobacteriae; in one patient Non-Hodgkin's lymphoma was found. The high occurrence of sinusitis in HIV-infected patients and the atypical findings in the sinus aspirates stress the importance of searching for sinusitis and the etiology to ensure the correct treatment.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Acoustic rhinometry: validation by three-dimensionally reconstructed computer tomographic scans.

The aim of the present study was a validation of acoustic rhinometry (AR) by computed tomography (CT). Six healthy subjects were examined by CT and AR. The CT data were processed in a computer program (AutoCAD), and a virtual three-dimensional model of each nasal cavity was constructed. This model permitted an individual prediction of the center line of the sound wave propagation through the air volume of the nasal cavity with the cross-sectional areas oriented perpendicularly to this line. The area-distance curves derived from AR and CT were compared. Linear regression analysis revealed a reasonable agreement of AR and CT in the anterior nose below a mean of 6 cm distance from the nostrils [r = 0.839, P < 0.01, m = 1.123, b = -0.113 (AR = m x CT + b)]. The measuring accuracy using CT as gold standard revealed a mean error at the nasal valve of <0.01 cm(2) (4.52%) and at the nasal isthmus of 0.02 cm(2) (1. 87%). Beyond 6 cm, the correlation decreased (r = 0.419), and overestimation of the true area occurred (>100%). In conclusion, the measurements were reasonably accurate for diagnostic use up to the turbinate head region. Certain factors induce an overestimation of the true areas beyond this region. However, these factors are constant and reproducible in a single subject, and intraindividual comparative measurements are possible beyond the turbinate head region.

Acoustics↗

PubMed2000

Acoustic rhinometry: recommendations for technical specifications and standard operating procedures.

This document is the result of the work and discussion of the Standardization Committee on Acoustic Rhinometry and presents guidelines for quality control and optimal application of acoustic rhinometry at its present stage. It is suggested that: 1. A well-defined standard nose is used for testing and optimising the equipment (data for a standard nose is given in the paper). 2. Procedures for evaluation of accuracy and repeatability of the measurements in the standard nose are presented, and error limits are defined for the area-distance curve as a whole, for the minimum cross-sectional area and for the volume from 0-5 cm into the nose. 3. Publication of results should include the volume 0-5 cm into the nose (volume from 2-5 cm for mucosal changes) the minimum cross-sectional area or preferably the two first minima and the distances to those areas. 4. The operator should be trained, follow a standard operating procedure and the environmental conditions (temperature and noise) be controlled. 5. Attention should be given to the nosepiece and the coupling between the equipment and the nose to obtain correct position, and sufficient seal without disturbing the anatomy. 6. The manufacturer should give information about the performance of the equipment, calibration procedures and maintenance, hygiene, environmental and safety standards.

Acoustics↗

PubMed2000

Nasal histamine challenge: a reproducible model of induced congestion measured by acoustic rhinometry.

We describe the development of a clinical model of nasal congestion using a fixed dose histamine challenge in normals. The objective was to use histamine to induce a similar degree of nasal congestion as a natural common cold (from unpublished data of 250 cold sufferers) and thus establish a rapid screening system for decongestant drug effects. Sixtynine normal subjects were challenged with histamine diphosphate (300 micrograms/nostril) on 2 visits. Thirtytwo subjects were identified showing reproducible baseline values (< 15%CV (coefficient of variation)) and adequate nasal congestion (minimum 20%) without excessive sneezing. Reproducibility was evaluated in them post challenge using acoustic rhinometry and rhinomanometry. Twentythree subjects showed a variation < 25%CV of nasal volume over multiple visits in a 5 month period. The average reduction in nasal volume and airflow 15 minutes post challenge was 32% and 41% respectively. Acoustic rhinometry values were less variable than rhinomanometry values. Negligible differences (< 2%) in histamine response over visits and similar correlation between measured values at first, second and last visits indicate that 2 visits are adequate to evaluate response reproducibility in a selected population. We conclude that it is feasible to develop a robust clinical model of nasal congestion using histamine.

Acoustics↗

PubMed1998

Acoustic reflections during rhinometry: spatial resolution and sound loss.

The accuracy of the acoustic reflections method for the evaluation of human nasal airway geometry is determined by the physical limitations of the technique and also by the in vivo deviations from the assumptions of the technique. The present study 1) examines the sound loss caused by nonrigidity of the nasal mucosa and viscous loss caused by complex geometry and its influence on the estimation of the acoustic area-distance function; 2) examines the optimal relation between sampling frequency and low-pass filtering, and 3) evaluates advantages of breathing He-O2 during the measurements on accuracy. Measurements made in eight plastic models, with cavities exactly identical to the "living" nasal cavities, revealed only minor effects of nonrigidity of the nasal mucosa. This was confirmed by an electrical analog model, based on laser vibrometry admittance measurements of the nasal mucosa, which indicated that the error in the acoustic measurements caused by wall motion is insignificant. The complex geometry of the nasal cavity per se (i.e., departure from circular) showed no significant effects on the measurements. Low-pass filtering of the signal is necessary to cut off cross modes arising in the nasal cavity. Computer simulations and measurements in models showed that the sampling frequency should be approximately four times the low-pass filtering frequency (i.e., twice the Nyquist frequency) to avoid influence on the result. No advantage was found for the the use of He-O2 vs. air in the nasal cavity.

Acoustic Stimulation↗

PubMed1997

Effect of corticosteroids on nasal blockage in rhinitis measured by objective methods.

This paper gives an overview of placebo-controlled studies of the effect of corticosteroid treatment on nasal blockage, based on objective measurements of nasal airway patency. A few studies of perennial rhinitis have indicated that pretreatment with an intranasal corticosteroid has a moderate effect on nasal hyperresponsiveness, measured as the histamine-induced increase of nasal blockage. Whereas the effect on allergen-induced early-phase symptoms is variable, the effect on the late-phase blockage is almost complete. In seasonal allergic rhinitis, a few studies have shown an effect of intranasal steroids on nasal airway resistance, nasal peak flow and on acoustic rhinometry, but there are no reports on the effect in adults with perennial rhinitis. In children with perennial disease, intranasal treatment results in increased nasal patency and, in one study, also in reduced mouth breathing and in an increased threshold for exercise-induced bronchoconstriction. In patients with nasal polyposis, intranasal steroids have an effect on nasal airway resistance and on nasal peak flow both before and after polypectomy. There is convincing evidence that intranasal corticosteroids provide a better effect than antihistamine on nasal blockage. Amazingly, there does not appear to be any report on the effect of systemic corticosteroid treatment on nasal airway patency, and it is therefore difficult to recommend this treatment in a rational dosage. In conclusion, there is a fairly good documentation in support of the efficacy of intranasal steroid treatment on nasal airway patency in rhinitis. An objective measurement of nasal airway patency ought to be the routine in controlled rhinitis trials.

Adrenal Cortex Hormones↗

PubMed1997

Prediction of nasal obstruction based on clinical examination and acoustic rhinometry.

The aim of this study was to find variables which characterize nasal obstruction. Scores from the clinical history, anterior rhinoscopy and objective values from acoustic rhinometry were found of importance. In a randomly-selected adult population of 230 individuals, 14% had the subjective feeling of nasal obstruction. The variables of significant value to predict nasal obstruction were: (1) symptoms of hypersensitivity/allergy and infection; (2) anterior septal deviations; and (3) small anterior dimensions of the nasal cavity. A minimum cross-sectional area (MCA) equal to 0.50 cm2, a cross-sectional area at the piriform aperture of 0.70 cm2 and a large effect of decongestion at MCA were found to be the best variables to separate obstructed from normal noses. Also, differences between each side of the nose were found of predictive value. In conclusion, a nose at risk for nasal obstruction is one with symptoms of allergy, frequent infections, small dimensions anteriorly, large difference between both sides, and a large degree of swelling of the mucosa.

Acoustics↗

PubMed1996

Acoustic rhinometry: influence of paranasal sinuses.

The influence of the maxillary sinuses in acoustic rhinometry (AR) has not been evaluated, and this is the aim of the present study. We examined six subjects with AR and magnetic resonance imaging (MRI) after nasal decongestion to compare the area-distance relationships determined by the two methods. From the MRI data we obtained copies of the nasal cavities with and without maxillary sinuses, which were made in plastic by a stereolithographic method. AR curves from models without maxillary sinuses differed from AR curves with sinuses included but were in agreement with MRI curves without inclusion of sinuses. A similar difference in AR was seen in two subjects before and after the nasal cavities were flushed with saline to fill up the maxillary sinuses. The measured volume in the first 50 mm of the nasal cavity models was unaffected by the sinuses, but the volume in the first 70 mm corresponding to the length of the nasal cavity septum was increased slightly but significantly (from 10.8 to 11.3 cm3; P = 0.05). The presence of maxillary sinuses increased the volume of the epipharynx (70-100 mm from the nostril) from 12.2 to 21.3 cm3 (P < 0.01), and this increase was not due to the influence from the contralateral nasal cavity. We conclude that the maxillary sinuses may significantly contribute to the acoustically determined areas in the posterior part of the nasal cavity and the epipharynx, especially during decongestion, and may explain a part of the difference between area-distance curves obtained by AR and MRI, whereas contribution from the contralateral nasal cavity does not.

Humans↗

PubMed1996

Bilateral inferior turbinoplasty in chronic nasal obstruction.

Bilateral inferior turbinoplasty was performed in cases of chronic nasal obstruction, in which conservative treatment had failed. Forty-five patients without significant septal deviation and with chronic nasal obstruction were objectively evaluated by acoustic rhinometry (AR) before and 3-6 months after turbinoplasty, in order to assess the changes of the dimensions of the nasal cavity obtained. Mucosal turbinate hypertrophy (defined objectively by AR) was present in 76% of the cases. Satisfactory subjective nasal patency was achieved in 93% of patients. Turbinoplasty resulted in an increase of 22% at the minimum cross-sectional area, 37% at the cross-sectional area 3.3 cm from the nostrils, and 47% at the cross-sectional area 4.0 cm from the nostrils. The increase was not related to the subjective result of the operation. Tendency to crusting and to vasomotor symptoms were related to unsatisfactory results. No crusting or bleeding were observed.

Adult↗

PubMed1995

Effect of terfenadine and budesonide on nasal symptoms, olfaction, and nasal airway patency following allergen challenge.

The study investigated the effect of the oral H1-blocker terfenadine on allergen challenge in subjects with nasal allergy in comparison with the topical steroid, budesonide. A randomized, placebo-controlled, double-blind, crossover study with 3 experimental days was performed outside the pollen season. Seventeen nonsmokers with hay fever (symptoms, positive skin prick test, and RAST against timothy) were treated for 14 days before each experimental day, where the response to nasal challenge with four different concentrations of timothy was measured every 15 min for 6 h. The nasal cavity dimensions were measured by acoustic rhinometry and the olfactory function as the threshold for the sense of smell of butanol. Nasal symptoms were determined by questionnaires. Both terfenadine and budesonide dry powder had an effect on the hay fever symptoms during nasal pollen challenge. Terfenadine was more efficient than budesonide against histamine-mediated symptoms such as sneezing and itching. Budesonide increased nasal airway dimensions better than terfenadine (P < 0.01). A marked effect of budesonide was seen 1-2 h after challenge, suggesting an effect on "early late phase" reaction in the nose. In 7/17 subjects, a significant (P < 0.05) improvement of olfactory function after budesonide treatment was seen. In conclusion, topical steroid (budesonide) is superior to antihistamine (terfenadine) in treatment of nasal congestion in hay fever, especially for the postchallenge reaction, and may, in some cases, relieve the decreased sense of smell during pollen challenge.

Administration, Inhalation↗

PubMed1995

Nasal histamine challenge in nonallergic and allergic subjects evaluated by acoustic rhinometry.

Nasal patency shows spontaneous variations but is influenced by a number of factors like exercise and allergic conditions. Nasal histamine challenge has been used to define nasal hypersensitivity. We have applied acoustic rhinometry as a new objective method to study the spontaneous variations of the nasal mucosa and its response to histamine challenge in 12 nonallergic subjects and 12 subjects with nasal allergy to pollen, but out of the pollen season. Measurements of the minimum cross-sectional area and the volume of the nasal cavities were done every 15 min for 6 h. More pronounced spontaneous variations, defined by the coefficient of variation of the measurements, were encountered in the allergic than in the nonallergic subjects, especially with regard to the minimum cross-sectional areas in the nasal cavities (P < 0.02). Allergic subjects showed increased sensitivity to histamine, as compared with nonallergic subjects, during low-concentration (0.1%) challenge (P < 0.05) and a prolonged effect of histamine challenge (P = 0.01). Antihistamine (cetirizine) had a significant effect on the histamine-induced symptoms and decrease of nasal dimensions during histamine challenge, but no significant effect on pollen-induced changes. In the allergic group, the decrease in minimum area during allergen provocation correlated with the level of specific IgE (r = 0.81; P = 0.0015).

Acoustics↗

PubMed1995

Spontaneous variations in congestion of the nasal mucosa.

BACKGROUND: Nasal patency shows spontaneous variations but is also influenced by exercise and allergic conditions. These variations have not been described in detail with regard to allergy. OBJECTIVES: The purpose of this study was to examine whether these variations are different in nonallergic subjects and in subjects with nasal allergy to pollen out of the pollen season. METHODS: We examined 12 of each type of subject in the winter on two days for seven hours in a climatic chamber with constant temperature and relative humidity, one day for examination of spontaneous variations and one day for examination of exercise response. Every 15 minutes the volume of the nasal cavities, minimum cross-sectional areas, and areas at fixed distances from the nostril were measured by acoustic rhinometry. Symptoms were scored by a questionnaire. RESULTS: There were more pronounced spontaneous variations expressed as the coefficient of variation of nasal volume in allergic than in nonallergic subjects (14% against 9%, P = .004). A nasal cycle was observed in four of the nonallergic subjects and three of the allergic subjects. In the postexercise period, the spontaneous variations in the nonallergic subjects were increased but decreased in the allergic subjects. Exercise increased nasal patency more in the allergic subjects but only significantly for the cross-sectional area at 3.3 cm (105% compared with 43% in the nonallergic subjects, P = .05). In contrast, pharmacologic decongestion in the allergic subjects showed a tendency to be more pronounced for the nasal cavity volume (55% increase versus 42%, P = .08). There was no difference between the groups in nasal symptom scores. CONCLUSION: Allergic subjects out of the pollen season have more congested and more sensitive nasal mucosa than nonallergic subjects.

Adolescent↗

PubMed1994

Nasal cavity dimensions in the newborn measured by acoustic reflections.

The acoustic reflections technique was used to measure nasal cavity dimensions in 27 newborns. The results were expressed in terms of curves describing cross-sectional area as a function of the distance into the nose. From these curves, a mean curve with 95% confidence limits, nasal cavity volumes between the nostril and 4.5 cm into the nasal cavity (V45 = 1.05 (0.24) cm3), the cross-sectional area at the narrowest site (Amin = 0.114 (0.033) cm2), and the distance from the nostril to Amin (DAmin = 1.14 (0.47) cm), expressed as mean and SD were calculated. There was a weak correlation between Amin and length and weight at birth, but otherwise nasal cavity dimensions did not correlate with sex, race, birth weight, birth length, head circumference, or duration of gestation. Comparison of the curves from the newborns with curves from adults showed a facial growth in vertical/transverse directions (area) of 600% and anterior/posterior directions of 120%. The technique of acoustic rhinometry is noninvasive, and can be performed rapidly, and is therefore eminently suitable for pediatric application. Further investigations are needed to demonstrate the value as a diagnostic tool in pathological cases.

Acoustics↗

PubMed1994

Posture and nasal patency: evaluation by acoustic rhinometry.

Nasal passage geometry was measured by acoustic rhinometry in 8 healthy medical students (5 males and 3 females, 21-29 years old; mean age 24 years) after 6 min in different postures of head and body. The minimum cross-sectional area (A-min) and volume between the nostril and 7 cm posteriorly were measured on both sides. When changing from sitting to horizontal the total airway dimension (i.e., the sum of A-min for the two sides) decreased by about 16% (Mean +/- SD = 0.19 +/- 0.14 cm2), and when standing up it increased by about 12% (0.14 +/- 0.13 cm2). A-min seemed more sensitive than volume to detecting postural changes. Including the variation between the cavities, the coefficient of variation (CV = SD/Mean) for area was 24.8 +/- 6.7 and for volume 22.4 +/- 6.4 for the 8 subjects. For the total nasal airway passage the corresponding figures were 12.9 +/- 3.9 and 10.9 +/- 5.5. These figures are considerably higher than for subjects measured only in the sitting position under comparable circumstances. In conclusion, our findings indicate a composite response of the nasal cavity mucosa to both systemic (hydrostatic) and local conditions, probably induced by vascular and cutaneous reflexes. These factors must be taken into account in studies of environmental, clinical, and pharmacological conditions.

Acoustics↗