Accuracy and repeatability of a pocket turbine spirometer: comparison with a rolling seal flow-volume spirometer

Respinos: A Portable Device for Remote Vital Signs Monitoring of COVID-19 Patients

The rapidly increasing number of COVID-19 patients has posed a massive burden on many healthcare systems worldwide. Moreover, the limited availability of diagnostic and treatment equipment makes it difficult to treat patients in the hospital. To reduce the burden and maintain the quality of care, asymptomatic patients or patients with mild symptoms are advised to self-isolate at home. However, self-isolated patients need to be continuously monitored as their health can turn into critical condition within a short time. Therefore, a portable device that can remotely monitor the condition and progression of the health of these patients is urgently needed. Here we present a portable device, called Respinos, that can monitor multiparameter vital signs including respiratory rate, heart rate, body temperature, and SpO2. It can also operate as a spirometer that measures forced vital capacity (FVC), forced expiratory volume (FEV), FEV in the first second (FEV1), and peak expiratory flow Rate (PEFR) parameters which are useful for detecting pulmonary diseases. The spirometer is designed in the form of a tube that can be ergonomically inflated by the patient, and is equipped with an accurate and disposable turbine based air flow sensor to evaluate the patient's respiratory condition. Respinos uses rechargeable batteries and wirelessly connects to a mobile application whereby the patient's condition can be monitored in real-time and consulted with doctors via chat. Extensive comparison against medical-grade reference devices showed good performance of Respinos. Overall results demonstrate the potential of Respinos for remote patient monitoring during and post pandemic.

Validity of a portable spirometer in the communities of China

Background

The lack of simple and affordable spirometry has led to the missed and delayed diagnoses of chronic respiratory diseases in communities. The PUS201P is a portable spirometry developed to solve this problem.

Objective

We aimed to verify the consistency of the PUS201P spirometer with conventional Jaeger spirometer.

Methods

In this cross-sectional study, we randomly recruited 202 subjects aged > 40 years. Testing with the portable spirometry and conventional spirometry were performed on all participants. We compared forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), FEV₁/FVC measured by the PUS201P device with the conventional spirometer. Pearson correlation coefficient and Interclass Correlation Coefficient (ICC) were assessed to confirm the consistency of the measures from two instruments. Bland–Altman graph was created to assess the agreement of the measures from two devices.

Results

202 participants were included in this study. The ICC on FEV₁, FVC, FEV₁/FVC measured by the portable spirometer and the conventional spirometer were 0.95 (95% confidence interval [CI]: 0.94–0.96), 0.92 (95% CI: 0.90–0.94], 0.93 (95% CI: 0.91–0.95), respectively. The Bland–Altman plots showed that the mean difference between the measures from two spirometers are always located in the 95% limits of agreement.

Conclusions

Our results support that the measures from the portable spirometer and the conventional spirometer have a good agreement and reproducibility. And the portable spirometer is a reliable tool to screen and diagnose chronic airway diseases in the primary care settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01872-9.

The Effects of Chest Wall Loading on Perceptions of Fatigue, Exercise Performance, Pulmonary Function, and Muscle Perfusion

Background: Load carriage (LC), which directly affects the chest wall and locomotor muscles, has been suggested to alter the ventilatory and circulatory responses to exercise, leading to increased respiratory muscle work and fatigue. However, studies exploring the impact of LC on locomotion increased internal work, complicating their interpretation. To overcome this issue, we sought to determine the effect of chest wall loading with restriction (CWL + R) on cycling performance, cardiopulmonary responses, microvascular responsiveness, and perceptions of fatigue. Methods: In a randomized crossover design, 23 young healthy males (22 ± 4 years) completed a 5 km cycling time trial (TT) in loaded (CWL + R; tightened vest with 10% body weight) and unloaded conditions. After baseline pulmonary function testing (PFT; forced expiratory volume in 1 s, FEV₁; forced vital capacity, FVC), cardiopulmonary indices (HR, heart rate; O₂ uptake, VO₂; ventilation, V_E; tidal volume, V_T; and breathing frequency, B_f), rating of perceived exertion (RPE), lactate (BLa), and microvascular responses (oxy-, deoxy-, total hemoglobin; and tissue saturation; StO₂) of the vastus lateralis using near infrared spectroscopy were collected during the TT; and PFT was repeated post-exercise. Results: Pre-exercise, CWL + R reduced (p < 0.05) FVC (5.6 ± 0.8 versus 5.5 ± 0.7 L), FEV₁ (4.8 ± 0.7 versus 4.7 ± 0.6 L), and FEV₁/FVC (0.9 ± 0.1 versus 0.8 ± 0.1). CWL + R modified power output (PO) over time (interaction, p = 0.02), although the 5 km time (461 ± 24 versus 470 ± 27 s), V_T (3.0 ± 0.3 versus 2.8 ± 0.8 L), B_f, V_E, HR, VO₂, microvascular and perceptual (visual analog scale, or VAS, and RPE) responses were unchanged (p > 0.05). CWL + R increased (p < 0.05) the average BLa (7.6 ± 2.6 versus 8.6 ± 3 mmol/L). Conclusions: Modest CWL + R negatively affects pre-exercise pulmonary function, modifies cycling power output over time, and increases lactate production during a 5 km cycling trial, although the cardiorespiratory, microvascular, and perceptual responses were unaffected.

Contact-Based Methods for Measuring Respiratory Rate

There is an ever-growing demand for measuring respiratory variables during a variety of applications, including monitoring in clinical and occupational settings, and during sporting activities and exercise. Special attention is devoted to the monitoring of respiratory rate because it is a vital sign, which responds to a variety of stressors. There are different methods for measuring respiratory rate, which can be classed as contact-based or contactless. The present paper provides an overview of the currently available contact-based methods for measuring respiratory rate. For these methods, the sensing element (or part of the instrument containing it) is attached to the subject's body. Methods based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity are presented. Working principles, metrological characteristics, and applications in the respiratory monitoring field are presented to explore potential development and applicability for each method.

Joint Indian Chest Society-National College of Chest Physicians (India) guidelines for spirometry

Although a simple and useful pulmonary function test, spirometry remains underutilized in India. The Indian Chest Society and National College of Chest Physicians (India) jointly supported an expert group to provide recommendations for spirometry in India. Based on a scientific grading of available published evidence, as well as other international recommendations, we propose a consensus statement for planning, performing and interpreting spirometry in a systematic manner across all levels of healthcare in India. We stress the use of standard equipment, and the need for quality control, to optimize testing. Important technical requirements for patient selection, and proper conduct of the vital capacity maneuver, are outlined. A brief algorithm to interpret and report spirometric data using minimal and most important variables is presented. The use of statistically valid lower limits of normality during interpretation is emphasized, and a listing of Indian reference equations is provided for this purpose. Other important issues such as peak expiratory flow, bronchodilator reversibility testing, and technician training are also discussed. We hope that this document will improve use of spirometry in a standardized fashion across diverse settings in India.

Impact of backpack type on respiratory muscle strength and lung function in children

We examine the influence of backpack type on lung function and respiratory muscle strength in children. Thirty-seven children were assessed for lung function and inspiratory and expiratory muscle strength under four randomly determined conditions: unloaded erect standing and three conditions carrying 15% of the child's body weight. In these three conditions, children carried the weight on a backpack with bilateral shoulder straps carried over both shoulders, on a backpack with bilateral shoulder straps carried over one shoulder and on a backpack with a mono shoulder strap. Significantly lower forced vital capacity, forced expiratory volume in one second and maximal expiratory pressure were observed when children carried a backpack with a mono shoulder strap compared to the unloaded standing position. In conclusion, the restrictive effect and the decrease in expiratory muscle strength were more pronounced for the backpack with a mono shoulder strap, suggesting that a double strap backpack is preferable to a mono shoulder strap backpack. Practitioner summary: There is little known about the effect of schoolbags on respiratory muscle function. We investigated the influence of backpack type on lung function and respiratory muscle strength. A backpack with a mono shoulder strap created a restrictive effect and a decrease in strength, suggesting that a double strap backpack is preferable to a mono shoulder strap backpack.

The AIMAR recommendations for early diagnosis of chronic obstructive respiratory disease based on the WHO/GARD model*

Respiratory diseases in Italy already now represent an emergency (they are the 3(rd) ranking cause of death in the world, and the 2(nd) if Lung cancer is included). In countries similar to our own, they result as the principal cause for a visit to the general practitioner (GP) and the second main cause after injury for recourse to Emergency Care. Their frequency is probably higher than estimated (given that respiratory diseases are currently underdiagnosed). The trend is towards a further increase due to epidemiologic and demographic factors (foremost amongst which are the widespread diffusion of cigarette smoking, the increasing mean age of the general population, immigration, and pollution). Within the more general problem of chronic disease care, chronic respiratory diseases (CRDs) constitute one of the four national priorities in that they represent an important burden for society in terms of mortality, invalidity, and direct healthcare costs. The strategy suggested by the World Health Organization (WHO) is an integrated approach consisting of three goals: inform about health, reduce risk exposure, improve patient care. The three goals are translated into practice in the three areas of prevention (1-primary, 2-secondary, 3-tertiary) as: 1) actions of primary (universal) prevention targeted at the general population with the aim to control the causes of disease, and actions of Predictive Medicine - again addressing the general population but aimed at measuring the individual's risk for disease insurgence; 2) actions of early diagnosis targeted at groups or - more precisely - subgroups identified as at risk; 3) continuous improvement and integration of care and rehabilitation support - destined at the greatest possible number of patients, at all stages of disease severity. In Italy, COPD care is generally still inadequate. Existing guidelines, institutional and non-institutional, are inadequately implemented: the international guidelines are not always adaptable to the Italian context; the document of the Agency for Regional Healthcare Services (AGE.NA.S) is a more suited compendium for consultation, and the recent joint statement on integrated COPD management of the three major Italian scientific Associations in the respiratory area together with the contribution of a Society of General Medicine deals prevalently with some critical issues (appropriateness of diagnosis, pharmacological treatment, rehabilitation, continuing care); also the document "Care Continuity: Chronic Obstructive Pulmonary Disease (COPD)" of the Global Alliance against chronic Respiratory Diseases (GARD)-Italy does not treat in depth the issue of early diagnosis. The present document - produced by the AIMAR (Interdisciplinary Association for Research in Lung Disease) Task Force for early diagnosis of chronic respiratory disease based on the WHO/GARD model and on available evidence and expertise -after a general examination of the main epidemiologic aspects, proposes to integrate the above-mentioned existing documents. In particular: a) it formally indicates on the basis of the available evidence the modalities and the instruments necessary for carrying out secondary prevention at the primary care level (a pro-active,'case-finding'approach; assessment of the individual's level of risk of COPD; use of short questionnaires for an initial screening based on symptoms; use of simple spirometry for the second level of screening); b) it identifies possible ways of including these activities within primary care practice; c) it places early diagnosis within the "systemic", consequential management of chronic respiratory diseases, which will be briefly described with the aid of schemes taken from the Italian and international reference documents.

Accuracy of office spirometry performed by trained primary-care physicians using the MIR Spirobank hand-held spirometer

BACKGROUND

With the availability of compact, portable, effective microspirometers, pulmonary function tests no longer need to be performed only in specialized laboratories. However, the perception persists that small flow-sensing devices are less accurate than volume-sensing spirometers.

OBJECTIVES

To study the accuracy of spirometry performed with the MIR Spirobank® and to investigate how accurately trained primary-care physicians can perform spirometry using a portable electronic spirometer.

METHODS

Patients with suspected occupational asthma were submitted to specific bronchial challenge tests in the pulmonary function laboratory according to published recommendations. Serial measurements were performed with the Jaeger MasterScope device (reference standard) or the Spirobank device. Data were generated from 908 parallel measurements on 34 patients. Furthermore, 16 patients with documented moderate to severe COPD were examined in a carousel set-up by four trained physicians who each used his/her own Spirobank device coupled to a laptop computer.

RESULTS

The Spirobank spirometer performed very well compared with the Jaeger MasterScope in a laboratory environment, displaying an underestimation of the forced expiratory volume in 1 s (FEV(1)) and FEV(1)/forced vital capacity (FVC) of 2-5%. High correlations were found for the pulmonary function parameters. The highest correlation was for FEV(1) (r(2) = 0.949) and the lowest for the maximum expiratory flow at 25% of FVC (MEF(25)) (r(2) = 0.864). Only 2% of the observed variation in the measurement results could be explained by the type of device.

CONCLUSIONS

The Spirobank device seems to be appropriate for research purposes if the standardized protocol is used correctly and the acceptability criteria are respected.

Accuracy and precision of desktop spirometers in general practices

BACKGROUND

Spirometry has become an essential tool for general practices to diagnose and monitor chronic airways diseases, but very little is known about the performance of the spirometry equipment that is being used in general practice settings. The use of invalid spirometry equipment may have consequences on disease diagnosis and management of patients.

OBJECTIVES

To establish the accuracy and precision of desktop spirometers that are routinely used in general practices.

METHODS

We evaluated a random sample of 50 spirometers from Dutch general practices by testing them on a certified waveform generator using 8 standard American Thoracic Society waveforms to determine accuracy and precision. Details about the brand and type of spirometers, year of purchase, frequency of use, cleaning and calibration were inquired with a study-specific questionnaire.

RESULTS

39 devices (80%) were turbine spirometers, 8 (16%) were pneumotachographs, and 1 (2%) was a volume displacement spirometer. Mean age of the spirometers was 4.3 (SD 3.7) years. Average deviation from the waveform generator reference values (accuracy) was 25 ml (95% confidence interval 12-39 ml) for FEV(1) and 27 ml (10-45 ml) for FVC, but some devices showed substantial deviations. FEV(1) deviations were larger for pneumotachographs than for turbine spirometers (p < 0.0031), but FVC deviations did not differ between the two types of spirometers. In the subset of turbine spirometers, no association between age and device performance was observed.

CONCLUSIONS

On average, desktop spirometers in general practices slightly overestimated FEV(1) and FVC values, but some devices showed substantial deviations. General practices should pay more attention to the calibration of their spirometer.

Hand-held turbine spirometer: agreement with the conventional spirometer at baseline and after exercise

Portable hand-held spirometers are widely used in outpatient clinics and in field surveys when examining children for asthma. However, the validity of the results obtained from the hand-held spirometers has not been assessed in population-based studies. We evaluated the agreement between the forced expiratory volume (FEV1) values got by the conventional flow volume spirometer (FVS) and the pocket-sized turbine spirometer (TS) at baseline and after exercise, among the 212 children screened for asthma and asthma-like symptoms from a population of 1633 school-aged children. The comparison was made between and within three diagnostic groups: clinical asthma (n = 34), possible asthma (n = 31), and controls (n = 147). In general, the differences in FEV1 between the FVS and the TS were small. For all children, the mean difference in FEV1 and the limits of agreement (difference +/-2 s.d.) was 0.05 l (0.23 to -0.13) at baseline and 0.06 l (0.24 to -0.12) after exercise. No significant differences were observed in the agreement between the diagnostic groups. In conclusion, although FEV1 results obtained by the hand-held spirometer are not interchangeable with those by the conventional spirometer, they are in reasonable agreement. The agreement is similar both at baseline and after exercise, and is not influenced by the presence of asthma.

Use of pocket-sized turbine spirometer in monitoring exercise-induced bronchospasm and bronchodilator responses in children

For field studies of asthma, portable hand-held pulmonary function testing devices are required. Other than for peak flow measurements, little has been done to validate their use in children. Fifty children aged 5-15 years having asthma symptoms were examined using an exercise challenge (8 min free running outdoors) and a bronchodilation test (salbutamol inhalation at a dose of 0.15 mg/kg). Pulmonary function was measured with a turbine spirometer, with a Wright peak flow meter (WPEF) and with a flow-volume spirometer (FVS). A fall of 15% or more in peak expiratory flow associated with wheezing or cough was considered diagnostic for bronchial hyper-responsiveness to exercise (BHRE). A rise of 15% or more from baseline in peak expiratory flow after salbutamol inhalation was considered as a positive bronchodilator response (BDR). BHRE was present in 16 children (32%). Using the limit of a 15% or greater fall in FEV1, turbine spirometry identified 12 as BHRE-positive and no additional cases, giving a sensitivity of 75% and a specificity of 100%. The turbine spirometer showed lower FEV1 values than the FVS, the difference increasing with airway obstruction. BDR was positive in eight children (16%). Using the limit of a 10% or greater rise in FEV1, turbine spirometry was positive in six cases. FEV1 measured by turbine spirometry could not be used interchangeably with conventional FVS. However, the turbine spirometer offers the possibility to measure FEV1 repeatedly in field conditions, such as during exercise challenges outdoors.

Interrupter technique for evaluation of exercise-induced bronchospasm in children

The free running test is a useful method for evaluation of exercise-induced bronchospasm in children. In young children this test simulates real-life circumstances and can be done more easily than histamine or methacholine challenges. The interrupter technique is a noninvasive method for measuring airflow resistance during tidal breathing. This approach requires minimal cooperation, and is therefore promising for use in young children. Fifty children aged 5-15 years with asthma symptoms were tested by exercise challenge consisting of free outdoor running for 8 min at 85% of maximal predicted heart rate for age. Pulmonary function was measured by using the interrupter technique (IR), with a Wright's peak flow meter (WPEF), and by flow-volume spirometry (FVS). The measurements were done before and 10 min after exercise. In addition, WPEF was measured at 5, 15, and 20 min after exercise. A fall of 15% or more in WPEF associated with wheezing or cough symptoms was considered a positive test. The exercise challenge was positive in 16 (32%) of the 50 children. Measurements at 10 min by WPEF identified 9 positive cases. At the same time point the IR identified 10 positive cases; a rise in resistance of 15% or more was considered positive, giving it 80% sensitivity and 93% specificity. The repeatability coefficient (CoR) for the interrupter technique was 0.06 kPa x L(-1) x s (13%) before and 0.07 kPa x L(-1) x s (14%) after exercise. The IR provides a useful alternative for estimation of airway obstruction in children following exercise challenge. The results were comparable with the current reference methods of forced expiratory volume in 1 s and peak flow measurements.

Pocket-sized spirometer for monitoring bronchial challenge procedures

Diagnosis of occupational asthma is verified by inhalation challenge testing when frequent monitoring of peak expiratory flow (PEF) or forced expiratory volume in 1 s (FEV1) is needed. FEV1 measurements also allow frequent monitoring of changes in small airways. For the follow-up of lung function of suspected occupational asthma, a reliable, personal and mobile device is needed. We studied the accuracy of a pocket-sized spirometer, Micro Plus Spirometer (MP), compared with our former combination of two devices, i.e. the values of forced expiratory volume in 1 s (FEV1) with those measured with the Vitalograph bellow spirometer (V); and the peak expiratory flow (PEF) values with the values obtained with a Wright PEF meter (W). In healthy control subjects, the values of FEV1 obtained with Micro Plus correspond well to those obtained using a bellow spirometer (R = 0.97) and the mean difference (MP-V) was -0.06 1 irrespective of the mean FEV1 value. W gives smaller PEF values than the MP; the mean difference in PEF (MP-W) was 44 1 min-1, but the values increased linearly with increasing flow. The poor relation between PEF values might be based on the low reliability of the Wright device. In patient follow-up, the FEV1 values measured with MP and V showed a good correlation (R = 0.99). The PEF values in patients increase linearly measured with W vs. MP with increasing flow values. In conclusion, we found the pocket-sized spirometer a handy and useful device for monitoring bronchial challenge procedures in patients with suspected occupational asthma. The number of exhalations during the challenge test follow-up is lessened when FEV1 and peak expiratory flow (PEF) can be measured simultaneously.

Repeatability of a rapid dosimetric method for methacholine challenge using a pocket turbine spirometer for FEV1 measurements

The repeatability of a rapid dosimetric method for methacholine challenge was evaluated with 11 asthmatic patients. A Spira Elektro 2 dosimeter was used for methacholine delivery and a pocket turbine spirometer (Micro Spirometer) for FEV1 measurements. Methacholine was delivered in four successive, increasing doses ranging from 80 micrograms up to a cumulative dose of 6900 micrograms. The single determination standard deviation was low (12.5%), corresponding to a 95% confidence interval of +/- 0.925 doubling doses. The mean difference (+/- SE) between measurements of log PD20 FEV1 was -0.015 (0.056), and the absolute value of the difference in log PD20 FEV1 was not significantly related to the average log PD20 FEV1 (r = -0.155, P = 0.65). The rapid dosimetric methacholine challenge test, performed with a pocket turbine spirometer, proved to be as reproducible as previous methods. Furthermore, this methacholine challenge is clearly less time consuming than conventional provocations, including bronchodilator aerosol (given to resolve post-challenge bronchoconstriction); the whole test can be performed in 20 min. This is especially valuable in epidemiologic studies, as well as in clinical practice.

Hyperventilation during exercise: independence on exercise-induced bronchoconstriction in mild asthma

Ventilatory gas exchange during exercise was compared in patients with mild asthma (11 females and 11 males), hyperventilation syndrome (HVS, 11 females), and healthy subjects (11 females and 11 males) in order to assess hyperventilation during exercise and its association with exercise-induced bronchoconstriction. The asthmatics showed decreased working capacity and decreased maximal oxygen consumption, with no evidence of limitation due to impairment of ventilatory capacity. Ventilatory equivalents for CO2 and O2 (VE/VCO2 and VE/VO2) at rest did not differ between the controls and asthmatics, but they were significantly elevated in HVS. In female asthmatics, ventilatory equivalents during exercise were significantly (P < 0.05) elevated compared with those of healthy subjects; in female controls, VE/VCO2 was 30.1 +/- 3.3 at low exercise and 27.4 +/- 6.5 at maximal exercise. In female asthmatics, the corresponding figures were 34.9 +/- 6.1 and 36.7 +/- 5.3. Furthermore, VE/VCO2 individually related to percent of maximal oxygen consumption (VO2max) was significantly increased in female asthmatics both at low and high VO2. The highest ventilatory equivalents were obtained in HVS, 41.7 +/- 6.7 and 43.9 +/- 0.9, respectively. Significant exercise-induced bronchoconstriction (decrease of FEV1 > 15%) was found in 50% of the asthmatics. The ventilatory equivalents did not correlate with exercise-induced changes in FEV1 (r2 < 0.3). Mild exercise-induced hyperventilation which was observed in mild female asthmatics, did not appear to be related to exercise-induced bronchoconstriction.

Controlled trial of methotrexate in patients with severe chronic asthma

The aim of this study was to investigate the efficacy and adverse effects of methotrexate (MTX) in the treatment of severe chronic asthma in 12 patients with severe asthma requiring continuous treatment with oral steroids at the Outpatient Department of Helsinki University Central Hospital. The study was a randomised, double-blind placebo-controlled trial of methotrexate treatment 15 mg weekly on a crossover basis over 24 weeks. During the 2 weeks baseline phase the mean dose of oral steroids administered was 10.9 (3.2-28) mg.day-1, and the mean dose of inhaled steroids administered was 2.3 (1.6-3.2) mg budesonide or beclomethasone. The average dose of oral steroids administered was 12.8 mg.day-1 during the last 2 placebo weeks but only 7.9 mg.day-1 during the last 2 weeks with MTX treatment. The reduction in daily dose of oral steroids was 38%, while daily bronchodilator use was reduced by 22%. During MTX treatment the patients experienced significantly less wheezing, dyspnoea and coughing. Nine out of 12 patients reported better asthma control during MTX treatment. The peak expiratory flow rate (PEF) 1-s forced expiratory volume (FEV1) values did not differ between MTX and placebo treatments. There was no statistical correlation between serum MTX concentration and clinical improvement. No serious adverse effects of MTX were found during the study. It was concluded that low-dose MTX may be beneficial for severe chronic asthma and that this therapy is well tolerated by patients.