One size does not fit all: universal cuff overestimates oscillometric blood pressure in persons with large arm circumference.

OBJECTIVE: Some brachial cuffs for oscillometric blood pressure (BP) measurement are claimed to cover a wide range of upper-arm circumferences; however, their validation is rarely conducted. Our aim was to compare oscillometric BP measurements obtained with a universal cuff with those obtained with an appropriately sized cuff. METHODS: We utilised the Microlife B6 Connect monitor, conducting oscillometric BP measurements in a random sequence with both a universal cuff (recommended for arm circumferences from 22 to 42 cm) and an appropriately sized cuff (medium for circumference 22-32 cm and large for 32-42 cm). We included 91 individuals with an arm circumference of 22-32 cm and 64 individuals with an arm circumference of 32-42 cm. RESULTS: For arm circumferences > 32 cm, systolic and diastolic BP measured with the universal cuff was higher than that measured with the large cuff (systolic 6.4 mmHg, 95% confidence interval [CI]). 3.9-8.8, diastolic 2.4 mmHg, 95%CI, 1.2-3.7, p < 0.001 for both). Overestimation of BP with the universal cuff was statistically significant after correcting for the sequence of measurements. No statistical difference was found between the universal cuff and medium cuff for circumferences in the 22-32 cm range. The bladder size in the universal cuff matched the dimensions of the medium-sized cuff; however, the cuff was larger. CONCLUSION: Overestimation of BP measured with a universal cuff in persons with large arm circumferences is clinically important. It poses the risk of unnecessary initiation or intensification of antihypertensive medication in persons using the universal cuff.

What is the context?Clinical guidelines recommend individualisation of the size of the cuff used for blood pressure measurement according to the circumference of the upper arm.Many blood pressure monitors are sold with a single "universal" cuff claimed to cover a wide range of upper arm sizes.We compared blood pressure obtained with the Microlife B6 Connect monitor and a "universal" cuff with the results obtained with individual sized cuffs (medium size for arm circumference between 22 and 32 cm and large size for arm circumference between 32 and 42 cm).What is new?In persons with large upper arm circumference is the systolic blood pressure 6.4 mmHg higher and the diastolic blood pressure 2.4 mmHg higher with the universal cuff than with the individual-sized large cuff.What is the impact?The universal cuff overestimates blood pressure in persons with large arm circumference.

Lower Arginine Bioavailability, Increased FeNO Levels, and Airway Resistance on Impulse Oscillometry Are Characteristics of Asthma in Children and Young Adults with Sickle Cell Disease.

Background and Objectives: Data on characteristics of asthma in children with sickle cell disease (SCD) is conflicting. Recently, the L-arginine pathway has gained attention in the pathogenesis of asthma and SCD. This study aimed to determine the distinctive clinical and laboratory features and the role of arginine metabolism in asthmatic children with SCD. Materials and Methods: A total of 52 children and adolescents with SCD, including 24 with asthma (SCD-A) and 28 without asthma (SCD-NA), and 40 healthy controls were included. A questionnaire, atopy tests, fractional exhaled nitric oxide (FeNO), and lung function tests were employed. Serum metabolites of the arginine pathway were measured. The results of the three groups were compared. Results: The demographic characteristics and atopy markers of the three groups were similar. FEV1%, FEV1/FVC, MMEF%, and total lung capacity (TLC%) values of SCD-A patients were not significantly different from the SCD-NA group, but they were significantly lower than the values measured in the controls. FeNO values greater than 35 ppb were present only in the SCD-A group. In impulse oscillometry, median resistance values at 5 Hz (R5)% were higher in both SCD subgroups than in healthy controls (p = 0.001). The (R5-20/R5)% values were higher in the SCD-A group (p = 0.028). Serum arginine levels and arginine bioavailability indices were significantly lower in the SCD-A group than in the SCD-NA group and healthy controls (p = 0.003 and p < 0.001). Conclusions: Asthma in children with SCD was not associated with atopy or low FEV1/FVC levels. However, lower arginine bioavailability and higher FeNO levels differentiated asthma in patients with SCD. High R5% and (R5-20/R5)% values indicated increased airway resistance in SCD, with a predominance of small airway disease in asthmatics.

Impulse oscillometry in patients with pulmonary arterial hypertension: an exploratory study.

INTRODUCTION: Studies suggest peripheral airway abnormalities in Pulmonary Arterial Hypertension (PAH). Impulse Oscillometry (IOS) is a noninvasive and sensitive technique for assessing the small airways. It evaluates the impedance of the respiratory system ‒ Resistance (R) and reactance (X) ‒ to a pulse of sound waves sent to the lungs, in a range of frequencies (5‒20 Hz). METHOD: Resistance variables: R5, R20, R5-R20 and reactance variables: AX (reactance area) and Fres (resonance frequency). The aim is to evaluate R and X in patients with idiopathic PAH (IPAH) and to investigate whether there is a correlation between IOS and spirometry. RESULTS: Thirteen IPAH patients and 11 healthy subjects matched for sex and age underwent IOS and spirometry. IPAH patients had lower FVC and FEV1 values (p < 0.001), VEF1/CVF (p = 0.049) and FEF 25-75 (p = 0.006) than healthy patients. At IOS, IPAH patients showed lower tidal volumes and higher AX (p < 0.05) compared to healthy individuals, and 53.8 of patients had R5-R20 values ≥ 0.07 kPa/L/s. Correlation analysis: X5, AX, R5-R20 and Fres showed moderate correlation with FVC (p = 0.036 r = 0.585, p = 0.001 r = -0.687, p = 0.005 r = -0.726 and p = 0.027 r = -0.610); Fres (p = 0.012 r = -0.669) and AX (p = 0.006 r = -0.711) correlated with FEV1; [R5 and R20, (R5-R20)] also correlated with FEV1 (p < 0.001 r = -0.573, p = 0.020 r = -0.634 and p = 0.010 r = -0.683, respectively) in the IPAH group. There were also moderate correlations of FEF 25-75 % with Z5 (p = 0.041), R5 (p = 0.018), Fres (p = 0.043) and AX (p = 0.023). DISCUSSION: Patients showed changes suggestive of increased resistance and reactance in the IOS compared to healthy individuals, and the IOS findings showed a good correlation with spirometry variables.

Respiratory Oscillometry and Functional Performance in Different COPD Phenotypes.

Purpose: Chronic obstructive pulmonary disease (COPD) phenotypes may introduce different characteristics that need to be known to improve treatment. Respiratory oscillometry provides a detailed analysis and may offer insight into the pathophysiology of COPD. In this paper, we used this method to evaluate the differences in respiratory mechanics of COPD phenotypes. Patients and Methods: This study investigated a sample of 83 volunteers, being divided into control group (CG = 20), emphysema (n = 23), CB (n = 20) and asthma-COPD overlap syndrome (ACOS, n = 20). These analyses were performed before and after bronchodilator (BD) use. Functional capacity was evaluated using the Glittre­ADL test, handgrip strength and respiratory pressures. Results: Initially it was observed that oscillometry provided a detailed description of the COPD phenotypes, which was consistent with the involved pathophysiology. A correlation between oscillometry and functional capacity was observed (r=-0.541; p = 0.0001), particularly in the emphysema phenotype (r = -0.496, p = 0.031). BD response was different among the studied phenotypes. This resulted in an accurate discrimination of ACOS from CB [area under the receiver operating curve (AUC) = 0.84] and emphysema (AUC = 0.82). Conclusion: These results offer evidence that oscillatory indices may enhance the comprehension and identification of COPD phenotypes, thereby potentially improving the support provided to these patients.

Comparison of Doppler ultrasonic sphygmomanometry, oscillometry and high-definition oscillometry for non-invasive blood pressure measurement in conscious cats.

OBJECTIVES: Systemic arterial hypertension is a common occurrence and can have serious adverse consequences in cats. Therefore, measuring blood pressure is very important. There are many indirect blood pressure measurement devices available. This study compared Doppler, oscillometric (petMAP Graphic II, SunTech Vet20, the Cardell Insight-X0000) and high-definition oscillometry devices for the non-invasive measurement of blood pressure in conscious cats. METHODS: In this prospective study, blood pressure was measured in 32 cats using the different devices according to the recommendations of the American College of Veterinary Internal Medicine Consensus Statement. Blood pressures (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP]), time to complete measurements, number of attempts needed, coefficient of variation (CV) between the blood pressure measurements of the different devices, ease of completing measurements and apparent stress level of the cat were assessed. RESULTS: There was a significant difference between devices in the time taken to obtain blood pressure readings and the number of attempts necessary to obtain six reliable measurements. The CV of the Doppler device was significantly smaller than that of the rest of the devices, but there were no other differences between the devices. The mean SBP, DBP and MAP measured by the petMAP device were significantly higher than the measurements from the other devices. The perceived ease of measurement was not significantly different between the various machines. The perceived level of stress of measurement with the Doppler device was significantly higher compared with the other devices but did not lead to an increased SBP. CONCLUSIONS AND RELEVANCE: Using a Doppler device to measure blood pressure in conscious cats is fast, relatively easy and gives reliable results. A disadvantage is that the Doppler device can only measure SBP, while oscillometric devices also provide DBP and MAP. However, in veterinary medicine, systolic hypertension is considered the most relevant.

Impulse Oscillometry as an Alternative Lung Function Test for Hospitalized Adults.

BACKGROUND: Impulse oscillometry (IOS) is a noninvasive technique that measures lung physiology independently of patient effort. In the present study, we aimed to investigate the utility of IOS parameters in comparison with pulmonary function testing (PFT) among hospitalized subjects, with emphasis on obstructive and small airway diseases. METHODS: Sixty-one subjects hospitalized either with unexplained dyspnea or for pre-surgery evaluation were included in the study. All subjects underwent PFTs and IOS test. The correlation between IOS results and PFTs was examined in different subgroups. The ability of IOS parameters to predict abnormal PFTs was evaluated using the area under the receiver operating characteristic (ROC) curve, and optimal cutoff values were calculated. RESULTS: IOS results were found to correlate with PFT values. Subgroup analysis revealed that these correlations were higher in younger (age < 70) and non-obese (body mass index < 25kg/m2) subjects. The resonant frequency was an independent predictor and had the best predictive ability for abnormal FEV1/FVC (area under the ROC curve 0.732 [95% CI 0.57-0.90], optimal cutoff 17 Hz, 87% sensitivity, 62% specificity) and abnormal forced expiratory flow during the middle half of the FVC maneuver (area under the ROC curve 0.667 [95% CI 0.53-0.81], optimal cutoff 15 Hz, 77% sensitivity, 54% specificity). Area of reactance and the difference in respiratory resistance at 5 Hz and 20 Hz also showed a good predictive ability for abnormal FEV1/FVC (area under the ROC curve 0.716 and 0.730, respectively). CONCLUSIONS: We found that the IOS performed well in diagnosing small airway and obstructive diseases among hospitalized subjects. IOS might serve as an alternative to standard PFTs in non-cooperative or dyspneic hospitalized patients.

The impact of respiratory reactance in oscillometry on survival in patients with idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a progressive disease with a poor prognosis. Pulmonary function tests (PFTs) aid in evaluating the disease status of IPF. The clinical significance of oscillometry measurements in interstitial lung diseases has recently been reported. Our previous study showed that respiratory reactance (Xrs) measured by oscillometry reflected disease severity and predicted subsequent lung capacity decline in patients with IPF. However, the direct impact of Xrs on survival needs to be determined, and there are currently no reference values in oscillometry to predict prognosis. Therefore, this study aimed to investigate the association between oscillometry measurements, particularly Xrs, and survival in patients with IPF and to determine the cutoff values of Xrs that predict 3-year survival. METHODS: We analyzed the relationship between the measured values of PFT and oscillometry derived from 178 patients with IPF. Univariate and multivariate Cox proportional hazards analyses were performed to investigate the relationships between clinical indices at the time of the first oscillometry and survival. We performed the time-dependent receiver operating characteristic (ROC) curve analysis to set the optimized cutoff values of Xrs for 3-year survival prediction. We examined the discriminating power of cutoff values of Xrs on survival using the Kaplan-Meier method and the log-rank test. RESULTS: Xrs components, especially in the inspiratory phase (In), significantly correlated with the PFT values. In the multivariate analyses, Xrs (all of reactance at 5 Hz [X5], resonant frequency [Fres], and low-frequency reactance area [ALX] in the inspiratory phase) had a significant impact on survival (X5, p = 0.003; Fres, p = 0.016; ALX, p = 0.003) independent of age, sex, and other prognostic factors derived from the univariate analysis. The area under the ROC curve was 0.765, 0.759, and 0.766 for X5 In, Fres In, and ALX In, with cutoff values determined at - 0.98, 10.67, and 5.32, respectively. We found significant differences in survival after dividing patients using each of the cutoff values of Xrs. CONCLUSIONS: In patients with IPF, Xrs measured by oscillometry significantly impacted survival. We also determined the cutoff values of Xrs to discriminate patients with poor prognoses.

Adding oscillometry to spirometry in guidelines better identifies uncontrolled asthma, future exacerbations, and potential targeted therapy.

The objective of this review is to provide new advances in our understanding of the clinical importance of establishing peripheral airway impairment (PAI) by impulse oscillometry (IOS) and targeted therapy, which could result in better asthma outcomes. Data sources include PubMed and Google search, limited to English language and human disease, with key words IOS and asthma. Key findings include PAI being consistently associated with uncontrolled asthma across ethnicities, using IOS reference equations factoring Hispanic and White reference algorithms. It is noted that PAI is common even in patients considered well-controlled by asthma guidelines. In a large longitudinal analysis (Assessment of Small Airways Involved in Asthma or ATLANTIS study), a composite of R5-R20, AX, and X5 ordinal scores were independently predictive of asthma control and exacerbation in a multivariate analysis, but forced expiratory volume in 1 second was not significantly predictive of morbidities. However, combining forced expiratory volume in 1 second less than 80% with PAI resulted in greater odds of identifying uncontrolled asthma and exacerbations, than either alone. Applying an external validation method in children with asthma offers the clinician the IOS reference equations best fit for their own specific population. Several clinical phenotypes can also identify PAI with high probability, useful when IOS is not available. Poor asthma outcomes for obese patients with asthma are associated with dysanapsis and PAI, not obesity alone. Extrafine inhaled corticosteroids achieve better asthma control and improve peripheral airway function with fewer exacerbations at lower dosages than nonextrafine inhaled corticosteroid aerosols. In conclusion, these data support the benefit of adding IOS to spirometry in future asthma guidelines and suggest the potential benefit from targeted therapy.

[The possibilities of impulse oscillometry in the diagnosis of the lung function disorders after COVID-19].

BACKGROUND: Impulse oscillometry (IOS) is an effort independent method of studying lung mechanics. AIM: To study the diagnostic significance of IOS in assessing lung mechanics after COVID-19. MATERIALS AND METHODS: Spirometry, body plethysmography, diffusion test (DLco), IOS parameters were analyzed in 315 patients (the median age 48 years), the median period from the beginning of COVID-19 to the study was 50 days. Statistical analysis included descriptive statistics, correlation analysis and one-dimensional logistic regression analysis with an assessment of odds ratios. RESULTS: In general group, spirometry and body plethysmography parameters were in normal values, while DLCO was reduced in 61% of patients. Parameters of IOS were analyzed in the general group and between the groups, depending on the value of DLco and total lung capacity (TLC): normal or reduced. In general group, reactance area (AX), hererogeneity of resistance Rrs5-Rrs20, resistance at 5 Hz (Rrs5), reactance at 5 Hz (ΔXrs5) were increased in 29.8%, 17.8%, 6%, 4.8% of patients, respectively, and were statistically significantly higher in the group with reduced TLC, whereas in the group with reduced DLco AX, Rrs5-Rrs20 were statistically significantly higher. Logistic regression analysis showed that patients with Rrs5-Rrs20>0.07 kPa×sec/l or AX>0.32 kPa/l had a 1.99-fold and 2.24-fold increased risk for decrease DLco, respectively, while the risk of decrease in TLC was 2.25-fold (p=0.012) and 3.16-fold (p<0.001) higher, respectively. CONCLUSION: IOS allow to detect both dysfunction of small airways (if AX or Rrs5-Rrs20 are increased) and the risk of restrictive pattern and lung diffusion impairment after COVID-19.

Oscillometry in Stable Single and Double Lung Allograft Recipients Transplanted for Interstitial Lung Disease: Results of a Multi-Center Australian Study.

Peak spirometry after single lung transplantation (SLTx) for interstitial lung disease (ILD) is lower than after double lung transplantation (DLTx), however the pathophysiologic mechanisms are unclear. We aim to assess respiratory mechanics in SLTx and DLTx for ILD using oscillometry. Spirometry and oscillometry (tremoflo® C-100) were performed in stable SLTx and DLTx recipients in a multi-center study. Resistance (R5, R5-19) and reactance (X5) were compared between LTx recipient groups, matched by age and gender. A model of respiratory impedance using ILD and DLTx data was performed. In total, 45 stable LTx recipients were recruited (SLTx n = 23, DLTx n = 22; males: 87.0% vs. 77.3%; median age 63.0 vs. 63.0 years). Spirometry was significantly lower after SLTx compared with DLTx: %-predicted mean (SD) FEV1 [70.0 (14.5) vs. 93.5 (26.0)%]; FVC [70.5 (16.8) vs. 90.7 (12.8)%], p < 0.01. R5 and R5-19 were similar between groups (p = 0.94 and p = 0.11, respectively) yet X5 was significantly worse after SLTx: median (IQR) X5 [-1.88 (-2.89 to -1.39) vs. -1.22 (-1.87 to -0.86)] cmH2O.s/L], p < 0.01. R5 and X5 measurements from the model were congruent with measurements in SLTx recipients. The similarities in resistance, yet differences in spirometry and reactance between both transplant groups suggest the important contribution of elastic properties to the pathophysiology. Oscillometry may provide further insight into the physiological changes occurring post-LTx.

Correlation of Impulse Oscillometry with Spirometry in Deployed Military Personnel with Airway Obstruction.

INTRODUCTION: Evaluation of chronic respiratory symptoms in deployed military personnel has been conducted at Brooke Army Medical Center as part of the Study of Active Duty Military for Pulmonary Disease Related to Environmental Deployment Exposures III study. Although asthma and airway hyperreactivity have been the most common diagnoses, the clinical findings in these patients may be multifactorial. This study aims to evaluate the utility of impulse oscillometry (IOS) in diagnosing airway obstruction in patients undergoing multiple pulmonary function testing (PFT) studies. METHODS: Military personnel referred for deployed-related pulmonary symptoms underwent a standardized evaluation at Brooke Army Medical Center and Walter Reed National Military Medical Center over a 5-year span. Initial studies included laboratory tests, high-resolution computed tomography imaging, cardiac evaluation with electrocardiogram, and echocardiography. PFT consisted of full PFTs, forced inspiratory/expiratory pressures, post-spirometry bronchodilator testing, IOS, exhaled nitric oxide, and methacholine challenge testing. RESULTS: A total of 360 patients have completed an evaluation to date. In this cohort, 108 patients (30.0%) have evidence of obstruction by spirometry, whereas 74 (20.6%) had IOS values of both an R5 > 150% and X5 < -1.5. Only 32 (8.9%) had evidence of obstruction by both spirometry and IOS, whereas 210 (57.3%) had neither. A comparison among R5 (resistance at 5 Hz), R20 (resistance at 20 Hz), and X5 (reactance at 5 Hz) was performed in those individuals with and without spirometric obstruction. R5 (% predicted) was 156.2 ± 57.4% (obstruction) vs. 129.1 ± 39.6% (no obstruction) (P < .001); R20 (% predicted) was 138.1 ± 37.7% (obstruction) vs. 125.3 ± 31.2% (no obstruction) (P = .007); and X5 (cmH2O/L/s) was -1.62 ± 1.28 (obstruction) vs. -1.25 ± 0.55 (no obstruction) (P < .001). DISCUSSION: Impulse oscillometry has been advocated as a supplemental pulmonary function test to aid in the diagnosis of airway obstruction. The use of IOS has been primarily used in pediatrics and elderly populations as a validated tool to establish a diagnosis of airway obstruction but is limited in the adult population because of a well-validated set of reference values. Prior studies in adults have most often demonstrated a correlation with an elevated R5 > 150%, elevated resonant frequency, and a negative X5 < -1.5 or a decrease of 30 to 35% in R5 post-bronchodilator. CONCLUSION: Impulse oscillometry may serve as an adjunct to diagnosis but likely cannot replace a standard spirometric evaluation. Our study highlights the future utility for diagnosing early obstructive disease in the symptomatic individual.

Using intra-breath oscillometry in obesity hypoventilation syndrome to detect tidal expiratory flow limitation: a potential marker to optimize CPAP therapy.

BACKGROUND: Continuous positive airway pressure (CPAP) therapy has profound effects in obesity hypoventilation syndrome (OHS). Current therapy initiation focuses on upper airway patency rather than the assessment of altered respiratory mechanics due to increased extrapulmonary mechanical load. METHODS: We aimed to examine the viability of intra-breath oscillometry in optimizing CPAP therapy for OHS. We performed intra-breath oscillometry at 10 Hz in the sitting and supine positions, followed by measurements at increasing CPAP levels (none-5-10-15-20 cmH2O) in awake OHS patients. We plotted intra-breath resistance and reactance (Xrs) values against flow (V') and volume (V) to identify tidal expiratory flow limitation (tEFL). RESULTS: Thirty-five patients (65.7% male) completed the study. We found a characteristic looping of the Xrs vs V' plot in all patients in the supine position revealing tEFL: Xrs fell with decreasing flow at end-expiration. Intra-breath variables representing expiratory decrease of Xrs became more negative in the supine position [end-expiratory Xrs (mean ± SD): -1.9 ± 1.8 cmH2O·s·L- 1 sitting vs. -4.2 ± 2.2 cmH2O·s·L- 1 supine; difference between end-expiratory and end-inspiratory Xrs: -1.3 ± 1.7 cmH2O·s·L- 1 sitting vs. -3.6 ± 2.0 cmH2O·s·L- 1 supine, p < 0.001]. Increasing CPAP altered expiratory Xrs values and loop areas, suggesting diminished tEFL (p < 0.001). 'Optimal CPAP' value (able to cease tEFL) was 14.8 ± 4.1 cmH2O in our cohort, close to the long-term support average of 13.01(± 2.97) cmH2O but not correlated. We found no correlation between forced spirometry values, patient characteristics, apnea-hypopnea index and intra-breath oscillometry variables. CONCLUSIONS: tEFL, worsened by the supine position, can be diminished by stepwise CPAP application in most patients. Intra-breath oscillometry is a viable method to detect tEFL during CPAP initiation in OHS patients and tEFL is a possible target for optimizing therapy in OHS patients.

Respiratory oscillometry and functional analyses in patients with idiopathic scoliosis.

Scoliosis is a condition that affects the spine and causes chest rotation and trunk distortion. Individuals with severe deformities may experience dyspnea on exertion and develop respiratory failure. Respiratory oscillometry is a simple and non-invasive method that provides detailed information on lung mechanics. This work aims to investigate the potential of oscillometry in the evaluation of respiratory mechanics in patients with scoliosis and its association with physical performance. We analyzed 32 volunteers in the control group and 32 in the scoliosis group. The volunteers underwent traditional pulmonary function tests, oscillometry, and the 6-minute walk test (6MWT). Oscillometric analysis showed increased values of resistance at 4 Hz (R4, P<0.01), 12 Hz (R12, P<0.0001), and 20 Hz (R20, P<0.01). Similar analysis showed reductions in dynamic compliance (Cdyn, P<0.001) and ventilation homogeneity, as evaluated by resonance frequency (fr, P<0.001) and reactance area (Ax, P<0.001). Respiratory work, described by the impedance modulus, also showed increased values (Z4, P<0.01). Functional capacity was reduced in the group with scoliosis (P<0.001). A significant direct correlation was found between Cobb angle and R12, AX, and Z4 (P=0.0237, P=0.0338, and P=0.0147, respectively), and an inverse correlation was found between Cdyn and Cobb angle (P=0.0190). These results provided new information on respiratory mechanics in scoliosis and are consistent with the involved pathophysiology, suggesting that oscillometry may improve lung function tests for patients with scoliosis.

Impulse oscillometry defined small airway dysfunction in asthmatic patients with normal spirometry: Prevalence, clinical associations, and impact on asthma control.

BACKGROUND: The small-airway dysfunction (SAD), detected with impulse oscillometry (IOS) methods, has been recently better characterized in patients with asthma. However, little is known about SAD in asthmatic patients with normal spirometry (NS). OBJECTIVE: In this study, we aimed to investigate, in an unselected sample of 321 patients with physician-diagnosed asthma and NS, prevalence, clinical characterization, and impact on asthma control of IOS-defined SAD. As a secondary objective of the study, we focused on comparing the difference between IOS- and spirometry-defined SAD. METHODS: Consecutive patients with a previous diagnosis of asthma but normal spirometry at the moment of the enrollment were stratified by the presence of IOS-defined SAD (difference in resistance at 5 Hz and at 20 Hz [R5-R20] greater than 0.07 kPa x s x L-1). We have also assessed the presence of SAD defined by spirometry, according to FEF 25-75 < 65% of the predicted. Clinical and laboratory features were collected, and univariable and multivariable analyses were used to analyze cross-sectional associations between clinical variables and outcomes (SAD). RESULTS: IOS-defined SAD was present in 54.1% of the cohort. In contrast, spirometry-defined SAD was present in only 10% of patients. Subjects with IOS-defined SAD showed less well-controlled asthma and a higher mean inhaled corticosteroid dosage use compared with subjects without SAD (both P < .001). Overweight (odds ratio [OR], 1.14; 95% CI, 1.05-1.23), exacerbation history (OR, 3.06; 95% CI, 1.34-6.97), asthma-related night awakenings (OR, 6.88; 95% CI, 2.13-22.23), exercise-induced asthma symptoms (OR, 33.5; 95% CI, 9.51-117.8), and controlled asthma (OR, 0.22; 95% CI, 0.06-0.84) were independently associated with SAD. CONCLUSIONS: Asthmatic patients with IOS-defined SAD showed less well-controlled asthma, more severe exacerbations and higher mean inhaled corticosteroid dosage. We confirmed exercise-induced asthma, asthma-related night awakenings, exacerbation history, and overweight as independently associated with SAD, while showing well-controlled asthma as inversely associated. SAD may be overlooked by standard spirometry.

Oscillometry in severe asthma: the state of the art and future perspectives.

INTRODUCTION: Approximately 3-10% of people with asthma have severe asthma (SA). Patients with SA have greater impairment in daily life and much higher costs. Even if asthma affects the entire bronchial tree, small airways have been recognized as the major site of airflow limitation. There are several tools for studying small airway dysfunction (SAD), but certainly the most interesting is oscillometry. Despite several studies, the clinical usefulness of oscillometry in asthma is still in question. This paper aims to provide evidence supporting the use of oscillometry to improve the management of SA in clinical practice. AREAS COVERED: In the ATLANTIS study, SAD was strongly evident across all severity. Various tools are available for evaluation of SAD, and certainly an integrated use of these can provide complete and detailed information. However, the most suitable method is oscillometry, implemented for clinical routine by using either small pressure impulses or small pressure sinusoidal waves. EXPERT OPINION: Oscillometry, despite its different technological implementations is the best tool for determining the impact of SAD on asthma and its control. Oscillometry will also be increasingly useful for choosing the appropriate drug, and there is ample room for a more widespread diffusion in clinical practice.

Lung Function Tests in Infants and Children.

Lung function testing is an essential modality of investigation in children as it provides objective evidence of lung disease/health. With advances in technology, various tests are available that can aid in the diagnosis of lung disease, assess the progression and response to therapy and document the lung development and evolving lung diseases in infants. This narrative review discusses lung function tests in infants and children. Currently, lung function tests can be performed in every age group, from neonates to the elderly. Spirometry and peak expiratory flow rate (PEFR) are the most employed tests in children more than six years of age. Spirometry helps diagnose and monitoring of both obstructive and restrictive diseases. There is a need for expertise to perform and interpret spirometry correctly. The forced oscillation technique (FOT) or impulse oscillometry (IOS) is done with tidal volume breathing and is feasible even in preschool children. Their utility is mainly restricted to asthma in children at present. Lung function tests can be performed in neonates, infants and children using infant pulmonary function test (PFT) equipment, although their availability is limited. Diffusion capacity for carbon monoxide (DLCO) is a valuable tool in restrictive lung diseases. Lung volumes can be assessed by body plethysmography and multiple washout technique. The latter can also assess lung clearance index. It is essential to perform and interpret the lung function test results correctly and correlate them with the clinical condition for optimum treatment and outcome.

Smartphone-Based Blood Pressure Monitoring via the Oscillometric Finger Pressing Method: Analysis of Oscillation Width Variations Can Improve Diastolic Pressure Computation.

OBJECTIVE: Oscillometric finger pressing is a potential method for absolute blood pressure (BP) monitoring via a smartphone. The user presses their fingertip against a photoplethysmography-force sensor unit on a smartphone to steadily increase the external pressure on the underlying artery. Meanwhile, the phone guides the finger pressing and computes systolic BP (SP) and diastolic BP (DP) from the measured blood volume oscillations and finger pressure. The objective was to develop and evaluate reliable finger oscillometric BP computation algorithms. METHODS: The collapsibility of thin finger arteries was exploited in an oscillometric model to develop simple algorithms for computing BP from the finger pressing measurements. These algorithms extract features from "width" oscillograms (oscillation width versus finger pressure functions) and the conventional "height" oscillogram for markers of DP and SP. Finger pressing measurements were obtained using a custom system along with reference arm cuff BP measurements from 22 subjects. Measurements were also obtained during BP interventions in some subjects for 34 total measurements. RESULTS: An algorithm employing the average of width and height oscillogram features predicted DP with correlation of 0.86 and precision error of 8.6 mmHg with respect to the reference measurements. Analysis of arm oscillometric cuff pressure waveforms from an existing patient database provided evidence that the width oscillogram features are better suited to finger oscillometry. CONCLUSION: Analysis of oscillation width variations during finger pressing can improve DP computation. SIGNIFICANCE: The study findings may help in converting widely available devices into truly cuffless BP monitors for improving hypertension awareness and control.

Spirometry and respiratory oscillometry: Feasibility and concordance in schoolchildren with asthma.

OBJECTIVE: The purpose of this study was to describe the feasibility of respiratory oscillometry (RO) in schoolchildren with asthma, and the concordance of its results with those of spirometry, to determine its clinical usefulness. METHODS: RO and spirometry were performed in 154 children (6 to 14-year-old) with asthma, following strict quality criteria for the tests. Their feasibility (probability of valid test, time of execution, number of maneuvers needed to achieve a valid test, and perceived difficulty) was compared. The factors that influence feasibility were analyzed with multivariate methods. FEV1, FEV1/FVC, FVC and FEF25-75 for spirometry, and R5, AX and R5-19 for RO, were converted into z-scores and their concordance was investigated through intraclass correlation coefficients (ICC) and kappa indices for normal/abnormal values. RESULTS: There were no differences in the probability of obtaining a valid RO or spirometry (83.1% vs. 81.8%, p = 0.868). RO required a lower number of maneuvers [mean (SD) 4.2 (1.8) versus 6.0 (1.6), p < 0.001] and less execution time [5.1 (2.7) versus 7.6 (2.4) minutes, p < 0.001], and patients considered it less difficult. Age increased the probability of obtaining valid RO and spirometry. The concordance of results between RO and spirometry was low, and only between zFEV1 and zAX could it be considered moderate (ICC = 0.412, kappa = 0.427). CONCLUSION: RO and spirometry are feasible in children with asthma. RO has some practical advantages, but the concordance of its results with spirometry is low.

Impulse oscillometry system for assessing small airway dysfunction in pediatric bronchiolitis obliterans; association with conventional pulmonary function tests.

Impulse oscillometry system (IOS) is a simple, and less invasive method for assessing small to total airway resistance in children. We analyzed the correlation between IOS, spirometry, and plethysmographic parameters performed for the diagnosis of pediatric BO patients. A total of 89 IOS assessments of pediatric BO patients or children without lung disease were included, and the relationship between pulmonary function tests (PFTs) and diagnostic performance was analyzed. R5, R5-20, X5, and AX were statistically significantly worse in the BO group. In general linear correlation analysis, R5% (adjusted ß [aß], -0.59; p < 0.001) and AX % (aß, -0.9; p < 0.001) showed the strongest correlation with conventional PFT parameters. R5% and AX % also showed the highest correlation with FEF25-75% (aß, -0.48; p < 0.001 and aß, -0.83; p < 0.001), and sRaw % (aß, -0.73; p = 0.003 and aß, -0.59; p = 0.008, respectively). Multivariate logistic regression analysis showed that R5 Z-score showed the highest ORs with FEV1 (OR = 3.94, p = 0.006), FEF25-75% (OR = 5.96, p = 0.005), and sRaw % (OR = 4.85, p = 0.022). Receiver operating curve analysis suggested AX % and R5% as the most optimal IOS parameters for BO diagnostic performance with the area under the curve of 0.915 and 0.882, respectively. In conclusion, R5 and AX are the parameters that can independently identify the severity of airway obstruction in pediatric BO patients without conventional lung function tests. IOS is an easy-to-perform, and reliable diagnostic method capable of detecting pathological obliteration of the small airways in children with BO.

Minimal clinically important difference for impulse oscillometry in adults with asthma.

BACKGROUND: Impulse oscillometry (IOS) allows an effort-independent evaluation of small airway function in asthma. Unfortunately, well-determined minimal clinically important differences (MCIDs) for IOS measures are lacking. Here, we provide MCIDs for frequently used IOS measures, namely frequency dependence of resistance (FDR) and area of reactance (AX), in patients with asthma. METHODS: We performed IOS at baseline and 1 year later in adult patients with mild-to-severe asthma (n=235). In a two-step approach, we first applied a distribution-based method to statistically determine the MCID. Next, we validated the proposed MCID according to patient-reported outcome measures (PROMs): Asthma Quality of Life Questionnaire (AQLQ), Asthma Control Questionnaire-7 (ACQ-7) and Asthma Control Test (ACT). We used multivariable analyses to investigate the proposed MCIDs as predictors for improvements in PROMs compared with the established MCID of forced expiratory volume in 1 s (FEV1). RESULTS: The proposed MCID was a decline of ≥0.06 kPa·L-1·s-1 and ≥0.65 kPa·L-1 for FDR and AX, respectively. Patients who had changes beyond the MCIDs for both FDR and AX showed greater improvements in all PROMs than those who had not. The mean improvements in PROMs were beyond the established MCIDs for ACQ-7 and AQLQ, and approximated the MCID for ACT. Multivariable analyses demonstrated the MCIDs for both FDR and AX as independent predictors for the MCIDs of all PROMs. The MCID for FDR was a stronger predictor of all PROMs than the MCID for FEV1. CONCLUSIONS: This study provides MCIDs for IOS-derived measures in adult patients with asthma and emphasises that small airway function is a distinguished end-point beyond the conventional measure of FEV1.