[Oscillometry, rheology and morpho-oscillometry. Importance and respective advantages].
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Coronary Disease↗
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Montelukast improves pulmonary function measured by impulse oscillometry in children with asthma (Mio study).
BACKGROUND: Systemic drugs-like oral montelukast can reach lower airways, whose inflammation plays a crucial role in the evolution of asthma, while inhaled drugs hardly reach them. The impulse oscillometry (IOS) technique is useful to evaluate both central and peripheral airways function. OBJECTIVE: To measure the effect of oral montelukast on airways resistance evaluated by oscillometry in children with asthma. METHODS: In an open study, respiratory function in 23 children with mild asthma and a positive bronchodilator response was assessed by spirometry and oscillometry. They took oral montelukast during 4 weeks and were again evaluated. As a control group, 23 similar patients with no preventive treatment underwent the same study. MEASUREMENTS AND MAIN RESULTS: Children on oral montelukast showed improvements (measured in kPa s L(-1)) in all oscillometry parameters: mean 0.20 (22.4%) in total respiratory impedance Zrs5, 0.18 (21.8%) in total airway resistance Rrs5, 0.09 (17.8%) in central airway resistance Rrs20, and 0.09 (28.8%) in distal capacitive reactance Xrs5; the frequency of resonance Fres improved 2.3 Hz (8.7%) (P<0.05 in all cases). No changes were found in the control group. Expiratory flows showed no changes except for a small (0.23 L s(-1), 7.4%) but significant worsening of FEF25-75 in the control group. CONCLUSIONS: Montelukast improves central and especially peripheral airways function in the first month of treatment, as evaluated by IOS, a technique based on tidal breathing analysis which is more sensitive than conventional forced spirometry.
Acetates↗
Impulse oscillometry is sensitive to bronchoconstriction after eucapnic voluntary hyperventilation or exercise.
Airway responses were compared following 6-minute eucapnic voluntary hyperventilation and 6-minute exercise challenges by examining resting and post-challenge impulse oscillometry and spirometry variables. Twenty-two physically active individuals with probable exercise-induced bronchoconstriction took part in this study. Impulse oscillometry and spirometry were performed at baseline and for 20 minutes post-challenge at 5-minute intervals. High correlation was found between the two measures of change in airway function for both methods of challenge. Impulse oscillometry detected a difference in degree of response to the challenges, whereas spirometry indicated no difference, suggesting that impulse oscillometry is a more sensitive measure of change in airway function.
Adolescent↗
Oscillometry of radial artery in acrocyanosis and cold sensitivity.
Acrocyanosis is reassessed on the basis of 34 new patients with diagnostic clinical features. The most useful tests are the skin temperature differences (STD) between wrist and end of fingers (or ankle and end of toes) and oscillometry over the radial and dorsalis pedis and posterior tibial arteries. Capillaroscopy of the conjunctival and nailfold vessels is useful in half the patients. Capillary resistance was not helpful. STD of 1.5 degrees C or more between skin of wrist or ankle and fingertip or toetip, is usually associated with more severe disease and capillary abnormalities on microscopy, and with reduced oscillometry (to 1 or less) over the radial arteries and dorsalis pedis and posterior tibial arteries. Reduced oscillometry is more associated with abnormalities than the other tests, and more than STD. The work of Mulvany and his colleagues suggests an explanation for the low oscillometry. Larger vessels than the arterioles and digital vessels can become resistance vessels in various circumstances. It is likely that the radial artery and vessels of similar diameter can temporarily act as resistance vessels in patients with acrocyanosis in a low temperature environment.
Adolescent↗
Measurement of physiological recovery from exacerbation of chronic obstructive pulmonary disease using within-breath forced oscillometry.
BACKGROUND: Within-breath reactance from forced oscillometry estimates resistance via its inspiratory component (X(rs,insp)) and flow limitation via its expiratory component (X(rs,exp)). AIM: To assess whether reactance can detect recovery from an exacerbation of chronic obstructive pulmonary disease (COPD). METHOD: 39 subjects with a COPD exacerbation were assessed on three occasions over 6 weeks using post-bronchodilator forced oscillometry, arterial blood gases, spirometry including inspiratory capacity, symptoms and health-related quality of life (HRQOL). RESULTS: Significant improvements were seen in all spirometric variables except the ratio of forced expiratory volume in 1 s (FEV(1)) to vital capacity, ranging in mean (SEM) size from 11.0 (2.2)% predicted for peak expiratory flow to 12.1 (2.3)% predicted for vital capacity at 6 weeks. There was an associated increase in arterial partial pressure of oxygen (PaO(2)). There were significant mean (SEM) increases in both X(rs,insp) and X(rs,exp) (27.4 (6.7)% and 37.1 (10.0)%, respectively) but no change in oscillometry resistance (R(rs)) values. Symptom scales and HRQOL scores improved. For most variables, the largest improvement occurred within the first week with spirometry having the best signal-to-noise ratio. Changes in symptoms and HRQOL correlated best with changes in FEV(1), PaO(2) and X(rs,insp). CONCLUSIONS: The physiological changes seen following an exacerbation of COPD comprised both an improvement in operating lung volumes and a reduction in airway resistance. Given the ease with which forced oscillometry can be performed in these subjects, measurements of X(rs,insp) and X(rs,exp) could be useful for tracking recovery.
Female↗
[Assessment of lung function using forced impulse oscillometry in cystic fibrosis patients].
The aim of this study was to evaluate the usefulness of forced impulse oscillometry to measure airway resistance in patients with cystic fibrosis. Thirty-four patients (20 men) with a mean age of 15 +/- 4 years were studied. All patients underwent forced impulse oscillometry, forced spirometry and body plethysmography. Correlations among spirometric, plethysmographic and oscillometric variables were analyzed. We found a statistically significant relation between both forced expiratory volume in one second (FEV1) and total airway resistance (Raw) and the following oscillometric variables: impedance (Zrs), resonance frequency (Fres), resistance to 5 hertz (Rrs5) and reactance to 5 hertz (Xrs5). The measurements that correlated most highly with classical pulmonary function tests were Zrs and Xrs5. Both resistance (Rrs) and reactance (Xrs) of the respiratory system were dependent on frequency. Their correlation with FEV1 and Raw were therefore lower when frequencies above 5 hertz were used. We conclude that airway resistances of cystic fibrosis patients can be adequately estimated by forced impulse oscillometry. This technique is a promising test of pulmonary function in such patients.
Adolescent↗
Noninvasive ankle pressure measurements by oscillometry.
Noninvasive ankle systolic, mean and diastolic pressures were obtained with an oscillometric instrument available commercially. Systolic pressures were also measured at either the posterior tibial or dorsal pedal artery by using the Doppler technique with the ultrasound probe. Ankle pressures were obtained in normal subjects and in patients with peripheral vascular disease, particularly patients with calcified or incompressible vessels or with different posterior tibial and dorsal pedal Doppler pressures. Systolic pressures by oscillometry and by Doppler were equal in normal subjects and in functionally normal limbs of patients. In the presence of mild vascular disease, systolic pressure was decreased and mean and diastolic pressures were within normal limits. Measurements by Doppler and by oscillometry were similar. In patients with moderate disease, the systolic pressure by oscillometry, although decreased, was consistently higher than Doppler pressures, and the mean ankle pressure was decreased. In patients with different posterior tibial and dorsal pedal pressures, the systolic oscillometric pressure was closer to the highest Doppler pressure measured. In contrast, in patients with partially incompressible vessels, the systolic oscillometric pressure was consistently lower than Doppler pressures. The oscillometric instrument available did not detect pressure pulses in patients with severe vascular disease; the weak pressure pulses present can, however, be detected with more sensitive instrumentation.
Journal Article↗
[Resistance by oscillometry. Comparison of its behavior in patients with asthma and cystic fibrosis].
This study aims to assess the behavior of the oscillometric parameters in 60 patients with bronchial asthma and in 39 with cystic fibrosis. All of them underwent an impulse oscillometry (IOS) and forced spirometry. The correlations existing between FEV1 and different oscillometric endpoints were assessed. In asthmatic subjects, the oscillometry parameters that correlated best with FEV1 were impedance (Zsr) and resistance to 5 hertz (Rsr5), while it was the Zsr and reactance to 5 hertz (Xsr5) in the individuals with cystic fibrosis. In the last group of patients, no correlation was found between FEV1 and Rsr in most of the frequencies evaluated. We conclude that there are differences in the behavior of the oscillometric parameters in patients with bronchial asthma and cystic fibrosis. The oscillometric parameters having the greatest use in the detection of the obstruction to airflow vary according to the disease studied.
Adolescent↗
Validation of impulse oscillometry in Friesian and Blue Belgian calves with respect to changes in extrathoracic upper airway resistance.
Impulse oscillometry (IOS) was compared with conventional pulmonary function techniques (using oesophageal balloon and airflow measurements). Healthy Friesian (FR) and Blue Belgian (BB) calves were examined in different conditions of extrathoracic airway resistance (physiological and vertical head position). Higher resistance values were detected in BB calves compared with FR calves with both conventional and forced oscillation techniques in both head positions. Upper airway narrowing was characterised by increasing resistance values without changes in frequency dependence. Measuring input impedance in animals using a face mask, a considerable capacitive shunt of the upper airways (including the capacitive components of the mask) has to be taken into account. Even if the absolute value of this capacitive component is constant, its influence on the measurement results increases with growing frequency and with an increase in upper airway resistance. In conclusion, (1) impulse oscillometry is sensitive to upper airway resistance changes and (2) face mask capacitance is important and has frequency dependent effects on the respiratory impedance.
Airway Resistance↗
Analysis of respiratory mechanics by impulse oscillometry in non-sedated and diazepam-sedated swine.
Analysis of respiratory mechanics using impulse oscillometry is applicable to sedated, or non-sedated (trained) pigs when they are fixed in a sling. In this study, the influence of the following sources of variability on measurement results was examined: (i) sedation with diazepam; (ii) body weight of animals (ranging in age: 40 to 102 days); and (iii) time of the measurement (circadian influences). The following parameters were examined: respiratory rate (RR), tidal volume (v(t)), spectral resistance, reactance and coherence, each at 5, 10, 15 and 20 Hz (R5,...R20, X5,...X20, CO5...CO20, respectively), distal respiratory resistance (Rdist), and proximal airway resistance (Rprox). After sedation (using 1.5 mg diazepam per kg body weight), RR and v(t) decreased significantly. There was a significant improvement of CO5, CO10 and CO15. Increase in body weight was strongly correlated to v(t), furthermore to spectral resistance parameters. Impulse oscillometry system (IOS) parameters showed only slight non-significant alterations in dependency on the time of day. In consequence, different sources of variability must be taken into account when performing IOS measurements in swine.
Age Factors↗
The effects of inhaled albuterol and salmeterol in 2- to 5-year-old asthmatic children as measured by impulse oscillometry.
The functional assessment of the response to bronchodilators in 2- to 5-year-old asthmatic children is technically difficult. For this reason, there have been no reports on the effects of long-acting bronchodilators, such as salmeterol, in this age group. Of the several techniques available for measuring resistance to airflow, forced oscillation remains the most adaptable to young children and the most practical for research and clinical use. In this stud we used the Jaeger MasterScreen Impulse Oscillometry System to assess the response of 2 to 5 year-old asthmatic children to an inhaled long-acting bronchodilator, salmeterol, by comparing it to the effect of a standard dose of the short-acting bronchodilator, albuterol. We performed a placebo-controlled, randomized, crossover study in 10 children aged 2 to 5 years who had a history of physician-diagnosed asthma and who were not on regular controller therapy. At weekly intervals after baseline measurements of reversibility, each child received two inhalations from an albuterol metered-dose inhaler (MDI) with a spacer (200 microg), or placebo MDI with spacer, or two inhalations from a salmeterol MDI (50 microg), or 50 microg from a salmeterol Diskus. Measurements were obtained at 5, 30, 60, 360, and 540 min, the last time interval only on the salmeterol days. Based on previous studies, total respiratory system reactance at 5 Hz (X5), calculated by the MasterScreen computer from mouth pressure and flow data, was used as the primary efficacy variable. The mean intra-individual variability in X5 was 10.5% (range 3.6% to 17.9%). The mean (SE) changes from baseline X5 at each time point were as follows: for placebo, 9.6 (3.0), 10.1 (2.6), 5.1 (2.9), 6.1 (3.5), p=0.36 vs. baseline; after treatment with albuterol, 32.7 (3.8), 53.9 (1.2), 47.3 (5.4), 18.1 (5.8), p<0.01 vs. baseline at all time points; after salmeterol MDI, 16 (6.4), 28.9 (5.2), 32.7 (3.9), 34.6 (4.4), 31.2 (4.8), p<0.05 at 60, 360, and 540 min; and after salmeterol Diskus, 16.4 (4.0), 16.9 (6.6), 27.8 (5.9), 28.6 (5.6), 33.8 (4.0), p<0.05 at 540 min. No significant adverse events or electrocardiographic changes were noted at any time. Impulse oscillometry is an acceptable method of assessing airway responses to bronchoactive drugs in this age group. Compared to albuterol and to its effect in older children and adults, the response to salmeterol Diskus appears to be somewhat blunted in this age group. The MasterScreen system is well suitedfor pharmacodynamic studies and clinical investigations in pre-school-aged children.
Administration, Inhalation↗
Method specificity of non-invasive blood pressure measurement: oscillometry and finger pulse pressure vs acoustic methods.
1. The agreement of blood pressure measurements by stethoscope auscultation (SBPa, DBPa-IV and DBPa-V), oscillometry (Dinamap; SBPo, and DBPo) and digital photoplethysmography (Finapres; SBPf, and DBPf) with the graphical analysis of the analogue microphone signals of vascular wall motion sound (SBPg and DBPg) was evaluated in eight healthy subjects in the presence of responses to the intravenous infusion of 1 microgram min-1 isoprenaline. 2. In general, there was good agreement between the SBP/DBP-measurements based on auscultatory Korotkoff-I- and IV-criteria and the reference method; the average method difference in estimating the isoprenaline responses for SBPa-SBPg was: -1.1, 95% CI: -5.4 to 3.1 mm Hg with a within-subject between-method repeatability coefficient (REP) of 11.6 mm Hg and for DBPa-IV-DBPg: 3.5, 95% CI: -0.5 to 6.5 mm Hg, REP: 11.5 mm Hg. The ausculatation of Korotkoff-V substantially overestimated the isoprenaline induced reduction of DBP: method difference DBPa-V-DBPg: -11.3, 95% CI: -17.8 to -4.7 mm Hg, REP: 31.8 mm Hg. 3. Oscillometry yielded good approximations for the SBP response to isoprenaline (average method difference SBPo-SBPg: -2.9, 95% CI: -9.0 to 3.3 mm Hg, REP: 17.6 mm Hg) but was poorly sensitive with regard to the DBP responses: method difference DBPo-DBPg: 6.5, 95% CI: -1.3 to 14.3 mm Hg, REP: 25.7 mm Hg. 4. Whilst the finger pulse pressure agreed well with regard to DBP (method difference for the DBP responses to isoprenaline: DBPf-DBPg: 1.8, 95% CI: -5.1 to 8.6 mm Hg, REP: 18.5 mm Hg) it was rather unsatisfactory with regard to SBP (method difference SBPf-SBPg: -14.1, 95% CI: -28.2 to -0.1 mm Hg, REP: 49.9 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenergic beta-Antagonists↗
Reference values for respiratory system impedance by using impulse oscillometry in children aged 2-11 years.
The forced oscillation technique makes it possible to evaluate the mechanical properties of the respiratory system with a minimum of cooperation. The method is therefore especially useful in children. Impulse oscillometry (IOS) is a commercially available version of this technique. There is, as yet, limited information on reference values for IOS in children. The aim of this study was to extend the reference values for IOS variables and to study their correlation with height, weight and age in healthy children. A sample (n = 360) of children (age 2.1-11.1 years) was measured by using impulse oscillometry (IOS; Jaeger, Würzburg, Germany). The sample was based on children attending kindergarten in Finland and children attending primary school in Sweden. Measurements of respiratory resistance (Rrs) and reactance (Xrs) at 5, 10, 15 and 20 Hz, total respiratory impedance (Zrs) and the resonance frequency (Fr) were made. All variables were related to body height. Most of them were also weakly related to weight. Reference equations for children (height 90-160 cm) are presented.
Age Factors↗
Measurement of respiratory impedance by impulse oscillometry--effects of endotracheal tubes.
Impulse Oscillometry is a new, noninvasive method to measure respiratory impedance, i.e. airway resistance and reactance at different oscillation frequencies. These parameters are potentially useful for the monitoring of respiratory mechanics in the critically ill patent with respiratory dysfunction. The endotracheal tube, used to mechanically ventilate these patients, however, represents an additional nonlinear impedance that introduces artifacts into the measurements. The objective of this work was therefore to investigate the effects of clinically available endotracheal tubes on resistance and reactance of an in vitro analogue of the respiratory system. Additionally, the effects of decreasing the compressible gas volume in this experimental model, as a simulation of decreased lung capacity and compliance, was investigated. Impulse oscillometric measurements of the test analogue gave highly reproducible results with and without an endotracheal tube. The tubes had significant influence on the measurement of the test object at all frequencies investigated. Changes of low frequent reactance were negligible - at least if repetitive measurements of the same system are performed - for realistic measurement of airway resistance, a correction of the tube impedance or measurement of the pressure distal of the tube is required. Resistance increased and low frequent reactance decreased significantly with decreasing gas volume. These changes were of magnitudes higher than the variations due to the introduction of the endotracheal tubes. Our results suggest that changes of respiratory reactance measured with impulse oscillometry may be used as a monitoring parameter in intubated patients.
Airway Resistance↗
Airway resistance in irritable bowel syndrome as measured by impulse oscillometry.
BACKGROUND: Irritable bowel syndrome (IBS) is associated with bronchial asthma. However, published data on airway resistance or impedance in patients with IBS but without any respiratory symptoms are lacking. METHODS: Patients with IBS but no respiratory symptoms underwent spirometry and airway resistance measurement using impulse oscillometry; the data were compared with those from 97 historical age- and sex-matched healthy control subjects. RESULTS: Patients had lower FEV1 (3.03 [0.74] vs. 3.35 [0.80] L/min; p=0.004) and FVC (3.56 [0.85] vs. 3.88 [0.9]; p=0.01) than healthy subjects; however, the values were within the normal range. Patients had a higher resistance at 5 Hz (0.45 [0.42] vs. 0.30 [0.15] kPa L/s; p=0.003); however, reactance at this frequency was not significantly different (-0.08 [0.30] vs. -0.10 [0.09] kPa L/s; p=0.438). CONCLUSION: Patients with IBS have increased airway resistance as compared to healthy subjects, as measured by impulse oscillometry; however, reactance is unchanged, indicating no change in elastic resistance.
Adult↗
Oscillometry and direct blood pressure: a comparative clinical study during deliberate hypotension.
Oscillometry using an automatic monitor was compared with invasive blood pressure monitoring in 21 patients scheduled for surgery under general anaesthesia with deliberate hypotension. Six ranges of mean blood pressure measurements were studied, two of which were hypotensive. An excellent correlation was found between the two methods (systolic: r = 0.94; mean: r = 0.93; diastolic: r = 0.88) but there was a large variability among individual subjects. For systolic, diastolic and mean intra-arterial readings above an approximative value of 10.64 KPa (80 mmHg), the oscillometric monitor was found to underestimate blood pressure. Inversely, it was found to overestimate blood pressure for intra-arterial readings under the approximative value of 10.8 KPa (80 mmHg). We conclude that the non-invasive monitor represents a good trend estimation of the invasive radial blood pressure technique, but that wide inter-individual variability and the overestimation of blood pressure below an approximative value of 10.64 KPa (80 mmHg) precludes interchange of techniques when absolute values are considered, especially during controlled hypotension. However, oscillometry could represent a better estimate of central aortic pressure.
Adult↗
Within- and between-day variability of respiratory impedance, using impulse oscillometry in adolescent asthmatics.
The objectives of the present study were to: 1) assess spirometric indices and respiratory impedance with forced oscillation (FO), using impulse oscillometry (IOS) in clinically stable asthmatic children over 3 consecutive days; 2) assess FO reactance (X), using an integrated index and resistance (R) separately during inspiration and expiration; and 3) assess effects on FO of hand support of cheeks vs. no hand support. Our hypotheses were: 1) because of increased sensitivity, IOS manifests day-to-day variability not demonstrable by spirometry; 2) IOS R during expiration exceeds that during inspiration; and 3) hand support of cheeks affects IOS R and X only minimally. We obtained triplicate twice-daily measures of IOS R and X in asthmatic adolescents at summer camp, in a convenience sample of children willing, with parental permission, to undergo repeated testing on consecutive days. Subjects received all medications between 6:30-7:30 AM, and were bronchodilated at time of testing. Subjects underwent IOS tests without hand support of cheeks, followed by tests with both hands supporting cheeks. ANOVA and regression analyses were used to discern technique differences.Significant differences in IOS inspiratory R5, R5 - R15 (frequency dependence of R), and low frequency reactance area (AX) occurred across 3 days, but spirometric indices were unchanged. Inspiratory R at 5 Hz (R5) was significantly smaller than expiratory R5 (P < 0.0001). ANOVA revealed no significant differences between hand and facial muscle cheek support for IOS R and X below 15 Hz, but significant differences occurred above 15 Hz. In conclusion, inspiratory R5, R5 - R15, and AX are sensitive measures for detecting changes in bronchomotor tone in adolescent asthmatic subjects, while expiratory R5 may be influenced by additional factors. Manual support of cheeks does not appear to affect IOS indices of peripheral airway obstruction in adolescent asthmatics. IOS is a practical method for quantifying respiratory mechanics, and its potential role in disease management warrants further study.
Adolescent↗
Impulse oscillometry: a measure for airway obstruction.
The impulse oscillometry system (IOS) was introduced as a new technique to assess airflow obstruction in patients who are not able to perform forced breathing maneuvers, e.g., subjects with cerebral palsy or severe mental retardation, and young children. This study evaluates the sensitivity and specificity of IOS parameters to quantify changes in airflow obstruction in comparison with forced expiratory volume in the first second (FEV(1)) and peak expiratory flow (PEF) measurements. Measurements of FEV(1), PEF, and resistance (R) and reactance (X) at frequencies of 5-35 Hz were performed in 19 children with asthma before, during, and after methacholine challenge and subsequent bronchodilatation. All parameters changed significantly during tests. Values of R5 and R10 correlated with FEV(1) (r = -0.71 and -0.73, respectively, P < 0.001), as did values of X5 and X10 (r = 0.52 and 0.57, respectively, P < 0.01). Changes in R preceded changes in PEF and FEV(1) during methacholine challenge. The area under the receiver operating characteristic (ROC) curve to predict a 15% fall in FEV(1) showed better sensitivity and specificity for R5 (area under the curve, 0.85) compared to PEF (0.79) or R10 (0.73). We conclude that IOS parameters can be easily used as an indirect measure of airflow obstruction. This might be helpful in patients who are not able to perform forced breathing maneuvers. In individual subjects, R values measured at 5 Hz showed to be superior to PEF measurements in the detection of a 15% fall in FEV(1).
Adolescent↗