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At least 181 records · Page 10Linked to original sources
PubMed1992

Oscillatory mechanics of the respiratory system in neuromuscular disease.

Respiratory impedance measurements by means of the technique of forced oscillations together with spirometry and measurements of maximal mouth pressures were performed in 27 patients with a variety of neuromuscular disorders to assess the value of adding respiratory impedance measurements in the evaluation of lung function in neuromuscular disease. Using the technique of forced oscillations, impedance measurements are easily performed in physically disabled persons, since they require little active cooperation and no forced respiratory maneuvers. Normal respiratory impedance characteristics were found, although resistance values were somewhat higher than those found in normal subjects, signifying the absence of airflow limitation. Spirometric values were markedly reduced, as were maximal mouth pressures. No significant correlations were found between the forced expiratory volumes in 1 s (FEV1) and the impedance data. A strong curvilinear relationship was observed between Pemax and the RV/TLC ratio and a strong correlation existed between FEV1 and Premax. It is concluded from our study that forced oscillometry is a useful tool for the assessment or exclusion of airflow obstruction in patients with neuromuscular disorders when plethysmography is difficult to perform and forced expiratory flow-volume data reflect muscle weakness rather than airflow limitation.

Adolescent↗
PubMed2003

Effect of aerosolized albuterol sulfate on resting energy expenditure determined by use of open-flow indirect calorimetry in horses with recurrent airway obstruction.

OBJECTIVE: To evaluate effects of sedation on stability of resistance of the respiratory system (RRS) and measures of resting energy expenditure (REE) by use of open-flow indirect calorimetry (IC) and treatment with aerosolized albuterol on REE in horses with recurrent airway obstruction (RAO). ANIMALS: 9 clinically normal horses and 8 horses with RAO. PROCEDURE: In phase 1, RRS was measured by using forced oscillometry (FOT) in 5 clinically normal horses before and after sedation with xylazine. In phase 2, REE was measured in 4 clinically normal horses between 20 and 25 minutes and again 35 to 40 minutes after sedation with xylazine. In phase 3, IC was performed between 20 and 25 minutes and FOT was performed between 30 and 35 minutes after xylazine administration in 8 horses with RAO; after administration of 450 microg of albuterol, IC and FOT were repeated. RESULTS: In phase 1, RRS values were significantly lower 5 and 10 minutes after sedation. In phase 2, diminishing sedation did not significantly affect REE. In phase 3, there was a significant decrease in mean RRS (1.15 +/- 0.25 vs 0.84 +/- 0.14 cm H20/L/s) and REE (30.68 +/- 17.89 vs 27.46 = 16.54 kcal/kg/d) after albuterol administration. CONCLUSIONS AND CLINICAL RELEVANCE: FOT and IC are useful in obtaining repeatable measurements of RRS and REE, respectively, in sedated horses. Concurrent bronchodilation and decreased REE after albuterol administration suggest that increased work of breathing as a result of airway obstruction may contribute to increased energy demands in horses with RAO.

Aerosols↗
PubMed2000

[Study on respiratory impedance of patients with extratracheal tumour].

OBJECTIVE: To determine the manifestation of impulse oscillometry (IOS) in variation of respiration impedance on patients with extratracheal tumour. METHODS: The IOS indices in 30 normal persons and 28 patients with extracheal tumour were measured. The ratio of forced expiratory volume after 1 second to forced vital capacity (FEV1/FVC) was evaluated and the maximal expiratory flow-volume curve (MEFV curve) was examined. The above values with t-test of SPSS statistics software were analyzed. RESULTS: Compared with the normal group, in the extratracheal group the ratio of actual value of resistance to the predict from 20 Hz to 35 Hz increased obviously and this only occurred with the reactance at 20 Hz (P < 0.01). The resistance curve showed clear rise after the 20 Hz and the reactance curve peaked at 20 Hz and was leveled to normal at 35 Hz. CONCLUSION: IOS is capable of presenting the distinctive indices for the study of respiration impedance on patients with extratracheal tumour.

Electric Impedance↗
PubMed2002

Determinants of respiratory system input impedance and bronchodilator response in healthy Finnish preschool children.

In order to study the determinants of respiratory system impedance and bronchodilator response in preschool children, a sample (n = 109) of healthy children (age 2.1-7.0 years) attending kindergarten was measured by using the impulse oscillometry. Their selection was based on a standardized questionnaire, negative skin prick test results and clinical examination, and sufficient cooperation. Triple measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs), the resonance frequency (Fr) and the frequency dependence of resistance (dRrs/df) were performed, to determine individual mean values. Measurements were repeated after inhalation of 300 microg salbutamol (n = 89) or placebo (n = 19). At the baseline, Zrs and Rrs5-20 showed negative, and Xrs5-20, Fr and dRrs/df positive correlations with age, height and weight. However, logarithmic transformed height was the best independent variable for the regression equations of all the oscillometric variables. After inhalation of placebo, none of the oscillometric variables changed significantly. In the salbutamol group, the mean (SD) change in Rrs5 was -0.187 (0.124) kPa l(-1) s(-1) and -19.2 (10.2)%, corresponding to a lower reference limit of -36.9%. Both the within-test and between-test repeatabilities for the measurement of respiratory resistance were acceptable, for Rrs5 the coefficients of variation being 6.2 and 6.1%, respectively. As the overall success rate in our sample was high (89%), the forced oscillation technique seems to be a useful method in assessing respiratory function and bronchial lability in preschool children.

Administration, Inhalation↗
PubMedDate not supplied

[Non-invasive blood pressure measuring device].

Algorithms have been developed for the Russian non-invasive blood pressure measuring monitor MPK-01 that applies a frequency excess pressure transducer. The monitor uses oscillometry. A preliminary estimate of the accuracy of blood pressure measurement for its conformity to the ANSI/AAMI (USA) and BHS (UK) standards has indicated the legitimacy of the algorithm proposed for processing if there are hardware restrictions inherent in this monitor.

Algorithms↗
PubMedDate not supplied

Accuracy of indirect measurement of blood pressure in neonatal foals.

The objectives of this study were to assess, in anesthetized neonatal foals, the accuracy of 2 automated indirect oscillometric monitors for measurement of mean arterial pressure (MAP), to determine the optimal site of cuff placement for MAP monitoring, and to determine the relationship between arterial blood pressure and cardiac output. Ten neonatal foals were anesthetized and instrumented with a catheter in the metatarsal artery for direct MAP monitoring and measurement of cardiac output by lithium dilution. Concurrent MAP measurements were obtained with Cardell and Dinamap oscillometric monitors with cuffs placed at 3 different sites (coccygeal, metatarsal, and median arteries). Blood pressure was manipulated by varying the depth of anesthesia and by administration of dobutamine or phenylephrine. A statistically significant (P = .025) interaction was found between the type of monitor and cuff placement site. With the Cardell monitor, placement of the cuff over the coccygeal artery resulted in a significantly lower bias than placement over the median or dorsal metatarsal artery (P < .0001 and P = .0149, respectively). No significant difference in bias was found with cuff placement site when using the Dinamap monitor. The correlation coefficient (r) between MAP and cardiac output was 0.47. Indirect oscillometry with a cuff placed over the coccygeal artery or dorsal metatarsal artery is an acceptable method for measuring MAP in foals. Blood pressure does not correlate well with cardiac output in anesthetized foals.

Animals↗
PubMedDate not supplied

[Interest of the noninvasive techniques for the measurement of the blood pressure in critical care].

OBJECTIVE: The goal of this study is to compare three techniques for the measurement of arterial blood pressure (invasive (I), oscillometric (O), and sphygmomanometric (S)) in critically ill patients to determine if the noninvasive techniques can replace the arterial catheterization, and to see whether the relation between these three methods varies over time. MATERIAL AND METHODS: Thiyty-three patients were recruited in the medical critical care unit at Hôtel-Dieu de France hospital. Each patient included had an arterial catheter inserted in the right femoral artery. The cuff of the oscillometer was positioned on the level of the right arm and measurements by sphygmomanometric technique were carried out on the level of the left arm. All measurements were taken at the same time, three times per day, during the patient stay in the critical care unit. RESULTS: The study period was five days with an overall of fifteen measurements for each technique. At t0, the calculation of the correlation coefficients of Spearman showed a very good correlation between the three measurements techniques for systolic (I/O: r = 0.7258, p < 0.001; I/S: r = 0.8824, p < 0.001; O/S: r = 0.8675, p < 0.001), diastolic (I/O: r = 0.7620, p < 0.001; I/S: r = 0.7910, p < 0.001; O/S: r = 0.7152, p < 0.001) and mean (I/O: r = 0.7725, p < 0.001; I/S: r = 0.8221, p < 0.001; O/S: r = 0.8363, p < 0.001) pressures. Between t1 and t15, analysis of variance (ANOVA) showed that the three methods remained well correlated (systolic p = 0.175; diastolic p = 0.107; mean p = 0.550). The calculation of the limits of agreement between the three techniques showed a lack of agreement between the invasive technique and the sphygmomanometric technique in 25% of the cases, and a good agreement between invasive and oscillometric techniques in 87.5% of the cases. CONCLUSION: Oscillometry can replace the direct intra-arterial standard technique for the monitoring of the blood pressure in the intensive care unit. In contrast, the sphygmomanometry in the ICU gives inaccurate results that could lead to inappropriate therapeutic attitudes.

Blood Pressure↗
PubMed1992

[Blood pressure measurement using the fingers].

An increasing number of devices for self-assessment of blood pressure has been developed over the past years. Accepted international standards for evaluation of such devices are still lacking. A new apparatus (T88, Marshall Electronics) measuring blood pressure on digital arteries by oscillometry was tested for accuracy. Comparative measurements in 36 patients indicated position-dependent results with a reasonable correlation with the measurements taken on the upper arm only if the device was used at the level of the heart. Significant differences for systolic values were noted on different phalanges. In a last series of measurements, comparing values obtained about the basal phalanges of the index positioned at the level of the heart, significant differences were found for systolic and diastolic values compared to the traditional measurement. The use of this device for evaluation of hypertension, monitoring of treatment or use in studies is thus not recommended.

Arteries↗
PubMed1991

[The variability of arterial pressure measured by oscillometric methods in premature newborn infants].

The variability of blood pressure measured by oscillometry and the validity of this technique were studied in premature infants. Thirty premature babies whose postnatal age was six days or more had their blood pressure measured 11 times over a twenty-minute period for three consecutive days. Movements were found to have a very substantial influence on results that could not be reliably compared with values obtained invasively. No consistent pattern of variations of oscillometric results obtained during the eleven measurements of use for recommending a specific measurement time was found. Diastolic blood pressure fell gradually over the three-day study period. The most reliable of the eleven daily values was the lowest value for which good correlations were found between the three study days; this lowest value was not influenced by neonatal or postnatal factors.

Analysis of Variance↗
PubMedDate not supplied

Forced oscillation technique. Reference values for resistance and reactance over a frequency spectrum of 2-26 Hz in healthy children aged 2.3-12.5 years.

The forced pseudo-random noise oscillation technique is a method by which total respiratory resistance (Rrs) and reactance (Xrs) can be measured simultaneously at various frequencies by means of complex oscillations, superimposed at the mouth during spontaneous quiet breathing. Reference values were obtained in 255 healthy Caucasian children of Dutch descent aged 2.3-12.5 years. Rrs and Xrs vs frequency (f) curves are mainly determined by the child's sex, age, height and weight. Taking complete Rrs and Xrs-f curves into account, we found that Rrs values were significantly higher in young boys than in young girls. They were equal at about 8 years, but at about 12 years of age Rrs values were again significantly higher in boys than in girls. Frequency dependence of Rrs was found in healthy boys up to about 5 years of age, but not in girls of the same age or in older children. These data suggest differences in airway diameter between boys and girls. At all ages Xrs was significantly lower in boys than in girls. This suggests differences in bronchial patency of peripheral airways, boys being at a disadvantage. It is concluded that multiple frequency oscillometry is a method which is ideal for children from the age of about 3 years. The possibility of measuring Rrs as well as frequency dependence of Rrs and Xrs simultaneously is the major advantage over other oscillation devices.

Adolescent↗
PubMed1981

[An automatic apparatus for external measurement of blood pressure. Preliminary study in patients with arteriopathies of the lower limbs (author's transl)].

An automatic measuring apparatus for recording blood pressure employing oscillometry was used to measure mean and elastic systolic and diastolic perfusion pressures in the ankles of arteritic patients. The reliability of the method was tested in 100 cases. Correlations with reference pressures measured by non-invasive techniques (ultrasonographic and plethysmographic) were good. The reliability and reproducibility of the apparatus employed (Dinamap) were in conformity with the desired maximum error (less than 15%). It is hoped that this method will allow improved evaluation of lower limb circulation, and the definition of a sliding scale of the indices of mean and elastic systolic and diastolic pressures. The major cause of error appears to be lack of pulsation in the leg arteries.

Arteritis↗
PubMed1996

Ambulatory blood pressure measuring devices.

During the last 6 years ABPM has become a widely used method in the diagnosis and treatment of hypertensive patients as well as in correlating the disease to prognosis. Up to January 1995, the international market offered 43 devices from 31 manufacturers. In Germany there are 18 devices available on the market from 10 different manufactures. Mainly, two different techniques are applied, ausculation and oscillometry, each having some advantages and disadvantages: The oscillometric technique may be preferable in patients with hyperkinetic circulation (e.g., pregnancy), with ausculatory gap and when surrounding noises are interfering, whereas the auscultatory technique, being the original method, has some advantages in patients with dysrhythmias and atrial fibrillation, as well as in dynamic (bicycle) exercise. The auscultatory method may be optimized by using ECG-, respectively oscillometric gating. The future development, which has already been realized in seven international recorders, offers the opportunity of either using auscultatory and/or oscillometric techniques during the same recording. To estimate the "true" sleeping interval more precisely a "day-night-button" at the recorder side is helpful. Furthermore, an uniform computer printout of the mean values of day- and night-time intervals, together with the widely approved limits of normotension should be achieved; last, but not least, an important factor for the widespread use of ABPM in general practice, as well as in the hospital, will be the prices of the recorders. Which have been reduced to about DM 3000-6000 in Germany (January 1996).

Blood Pressure Monitors↗
PubMed1996

Automated blood pressure measurement in children.

Techniques to measure blood pressure are even more complicated in children and particularly in infants as in adults, since appropriate cuff sizes and special reference values are necessary. In pediatric patients oscillometry is the automated method of choice and is in use since more than 15 years (Dinamap). Recently, ambulatory blood pressure measurement (ABPM) with an oscillometric device (SpaceLabs) has become a valuable too in the diagnosis and therapeutic monitoring of arterial hypertension of children and adolescents. Normal casual blood pressure measurements have been studied in large studies demonstrating an increase of systolic and diastolic blood pressure with age, or even more with body height. These reference values are not applicable to evaluate ABPM. Recent studies in single centers as well as a multicenter study (of 1141 participants) have provided pediatric reference values for ABPM. Daytime mean systolic blood pressure increased with height from 111 to 120 mm Hg in girls (body height 120 to 180 cm) as well as in boys from 112 to 124 mm Hg. However, daytime mean diastolic blood pressure did not change during maturation and was 72 to 74 mm Hg irrespective of height and sex. The upper normal values (95th percentile) were 13-15 mm Hg above the mean. Since there is a striking difference between normal casual blood pressure and normal ABPM in children, it is essential to use appropriate blood pressure references.

Adolescent↗
PubMed1997

[Predictability of model size in impulse oscillometric airway resistance measurements in animals (calf)].

The aim of this study was to investigate the behaviour of parameters which can be obtained by a 7-component model of the lung using impulse oscillometry in calves. Seven healthy conscious calves were examined using "Master Screen IOS" (E. Jaeger GmbH & Co. KG, Würzburg/D) and the following study design: [I] baseline measurements, [II] measurements after inhalation saline, [III] measurements during carbachol-induced bronchoconstriction, [IV] measurements after bronchodilatation by fenoterol. Measurements were made individually using a rigid face mask. Examining the spectral behaviour of the respiratory impedance (5 to 35 Hz), reactance (X) was more sensitive to bronchochallenge (stages [all] and [IV]) than resistance (R). Using the 7-component model of the lung, the resistance was differentiated into a central part (Rz) and a peripheral part (Rp). Changes in Rp were more significant than changes in Rz during stages [III] and [IV]. The parameters central inertance (Lz), chest wall compliance (Cw), and lung compliance (Cl) did not change during the study. Surprisingly, the parameter called "bronchial compliance" (Cb) increased significantly during bronchoconstriction. Therefore, further research is necessary to clarify whether the model needs to be modified for general applications or only for measuring bovines.

Airway Resistance↗
PubMed1997

[Diurnal profile of impulse oscillometric impedance in healthy subjects].

Diurnal profiles of impulse oscillometry during 24 hours in 3 hour intervals in sitting and lateral lying position have been studied in 20 healthy female and male probands 10-67 years of age. Approximating the profiles by a sine-cosine-function the amplitude of resistance was found up to 3, that of reactance up to 1 hPa/l/s in single cases, preferably for end-expiratory values and for the resistance-flow- and the resistance-volume-gradients, more pronounced in lying than in sitting position. The daytime reaching maxima of resistance and minima of reactance is different in single individuals. Single persons with obviously high vitality or sensibility showed very high amplitudes reproducible within IOS measuring limits of 0.2 hPa/l/s after 6 months.

Adolescent↗
PubMed1997

[Overview of the most frequent clinical manifestations of peripheral arterial occlusive disease in the elderly, its diagnosis and stage-related therapy].

The peripheral artery occlusive disease is a widely spread disease and its diagnosis, treatment options and consequences are frequently underestimated. Especially for the old patient, preservation of an extremity may mean mobility and quality of life. The increasing life expectancy and behaviour of prosperity including a lack of mobility are causing a rise in the frequence of atherosclerotic diseases. The prevalence of occlusive vascular diseases in patients between 55 to 64 years of age is currently 11% and is, therefore, a wide-spread disease. However, the socio-economic relevance of the occlusive vascular diseases is frequently underestimated. It causes both very high direct costs (treatment procedures, prostheses etc) as well as high indirect costs (permanent disability). Therefore, early diagnosis and treatment plays an important role in the avoidance of a progression of the disease. For an early diagnosis of the stage I of occlusive vascular diseases it makes sense to examine the vessels of patients at risk (i.e. diabetes mellitus, hypertension, hyperlipidemia, nicotine abuse, and overweight). Dopplerultra-sound and oscillometry are highly sensitive and specific diagnostic measures. The eradication of risk factor and the treatment of the secondary diseases plays the most important role in this disease stage without symptoms. A specific vessel training is indicated during stage II to encourage the development of collateral blood flow. Additionally, an interventional diagnostic and therapy should be considered in this stage with limitations in the daily activities. The administration of vasoactive drugs is controversly discussed. The acetylsalicylic acid (ASA) is remaining the most investigated substance for reducing the progress of the arteriosclerotic process. The administration of ticlopidine is justified in cases of ASA-allergies. The stages III and IV are characterized by pain at rest and necrosis. Firstly, the indication for a transcutaneous transluminal angioplasty, thrombolysis or bypass-surgery should be proofed. If procedures of revascularization are not possible, prostaglandines may improve the pain at rest and wound healing. Beside the stage of the occlusive vascular disease, the presence of risk factors, the physical status of the patient, and the location of the occlusion are of great importance for the decision about the treatment procedure.

Adult↗
PubMedDate not supplied

[Review of respiratory mechanics in animals. 3. Methodical and physiologic aspects of the use of the impulse oscilloresistometry system (OIS)].

The impulse oscillometry system (IOS) which was originally developed for human medicine was found to be suitable for analysing respiratory mechanics in spontaneously breathing animals. This technique is non-invasive. METHODOLOGICAL ASPECTS: In order to use the IOS-technique in animals, a tightly fitting face mask is necessary. Furthermore, a flexible tube needs to be inserted into the measuring system. While the tube does not influence the measured results significantly, the face mask may affect the measurements. Therefore, its influence on the measured respiratory impedance must be taken into account. To prevent methodological errors, the head and body position of the animal should be standardised during the IOS-measurement. Since the methodological variability of the system is very small, the measuring results are highly reproducible. PHYSIOLOGICAL ASPECTS: In growing subjects, all parameters of respiratory mechanics depend on body weight. Since respiratory physiology is influenced by circadian rhythms, measurements of different days are only comparable when they have been done each day at the same hour. Comparing the respiratory impedance of different animals of similar age and body weight, a considerable inter-individual variability was observed. Due to the low level of physiological intra-individual variability, the method seems to be especially useful for studying influences on the respiratory system (i.e. pharmaceutics, therapeutics) in long-term studies using the same group of subjects.

Animals↗
PubMedDate not supplied

[Review of respiratory mechanics in animals. 4. The diagnostic affirmation ability of research using the impulse oscilloresistometry system (IOS) in calves].

Taking methodological and physiological aspects into account (see Part 3), the impulse oscillometry system (IOS) was found to be sensitive to detecting and to quantifying clinically relevant changes in respiratory mechanics in calves. Therefore, the complex respiratory impedance needs to be measured in terms of resistance and reactance within the frequency range between 5 Hz and 20 Hz. The behaviour of resistance and reactance in dependence of frequency allows to differentiate and to localise airway obstructions. Obstructions of upper (extrathoracic) airways were mainly characterised by a frequency independent increase in the resistance. Within the reactance curve, no change in the resonant frequency could be observed. In a peripheral airway obstruction both resistance and reactance changed. The most typical finding concerning resistance was that a negative frequency dependence occurred. The reactance became more negative. Following this, the resonant frequency increased. With progressive obstruction of the peripheral airways, the reactance became more informative than resistance.

Airway Obstruction↗