The effect of patient technique and training on the accuracy of self-recorded peak expiratory flow

Praćenje vršnog ekspiratornog protoka u dijagnozi profesionalne astme

Prema podacima iz Registra profesionalnih bolesti Hrvatskoga zavoda za zaštitu zdravlja i sigurnost na radu, u posljednjih deset godina (2008. ‒ 2017.) prijavljeno je samo 20 slučajeva profesionalne astme od ukupno 2234 prijavljene profesionalne bolesti. To upućuje na značajne nedostatke u prepoznavanju toga poremećaja u našoj radnoj populaciji. Cilj ovoga rada bio je opisati standardnu metodu praćenja vršnog ekspiratornog protoka zraka (eng. peak expiratory flow, PEF) i predložiti praktičnu smjernicu za korištenje te dijagnostičke metode u ambulantama medicine rada i sporta. Praćenje vršnog ekspiratornog protoka zraka (PEF-monitoring) jednostavna je, jeftina, neinvazivna i pouzdana metoda za utvrđivanje funkcije dišnog sustava u stvarnim uvjetima rada i radnog okoliša. Sadašnje smjernice preporučuju PEF-monitoring kao inicijalnu dijagnostičku metodu prilikom sumnje na profesionalnu astmu. Pozitivan test upozorava na povezanost promjene plućne funkcije s radnom izloženošću i važan je dio dijagnostičkoga procesa utvrđivanja profesionalne astme. Najveći je nedostatak te metode da se tim testom ne može utvrditi uzrok astme, tj. on ne razlikuje profesionalnu astmu od astme pogoršane na radu, nema standardizirane metode za interpretaciju rezultata, a mjerenja provode sami radnici pa su moguće namjerne i nenamjerne manipulacije rezultatima mjerenja. U radu je predložena praktična smjernica za primjenu te metode u ambulantama medicine rada i sporta, s preporukama protokola mjerenja PEF-a, prikaza rezultata mjerenja i njihove interpretacije u sklopu dijagnosticiranja profesionalne astme.

Breath tests in respiratory and critical care medicine: from research to practice in current perspectives

Today, exhaled nitric oxide has been studied the most, and most researches have now focused on asthma. More than a thousand different volatile organic compounds have been observed in low concentrations in normal human breath. Alkanes and methylalkanes, the majority of breath volatile organic compounds, have been increasingly used by physicians as a novel method to diagnose many diseases without discomforts of invasive procedures. None of the individual exhaled volatile organic compound alone is specific for disease. Exhaled breath analysis techniques may be available to diagnose and monitor the diseases in home setting when their sensitivity and specificity are improved in the future.

Increased diagnosis of asthma in hospitalized infants: the next target population for care management?

Hospitalization of children with asthma declined at our institution between 1996 and 2000, before stabilizing for the past 5 years. The ages of children hospitalized since 2000 were examined to see if the demographics of the hospitalized population have changed to better understand why the hospitalization rate has remained the same despite continued, aggressive screening and education efforts. Data were gathered for our hospital through the Department of Defense Medical Health System Management Analysis and Reporting System (M2). The mean age (+/- SD) of children hospitalized in 2003 (2.84 +/- 2.53) was less than the mean age for 2000 and 2002 (4.85 +/- 3.7 and 4.61 +/- 4.45), respectively (p < 0.05), and more infants less than 2 years of age were hospitalized in 2003 (33/60, 55% p < 0.01) and 2004 (32/68, 47% p < 0.05) than in 2000 (19/70, 27%). The diagnosis of asthma in hospitalized infants and young children has increased over the past 5 years, suggesting better recognition and providing a new target population for intervention with early asthma controller therapy.

The influence of corticosteroids on the perception of dyspnea in asthma

Corticosteroids are effective anti-inflammatory medications that are recommended for the control of persistent asthma. Little, however, is known about their influence on the perception of dyspnea, which, in turn, is important to the successful self-management of asthma. This paper provides a synopsis of available studies examining the impact of corticosteroids on the sensitivity to perceive dyspnea and presents possible mechanisms underlying this relationship. The results of these investigations are conflicting with some studies showing improved perception and other studies showing worsened perception of dyspnea after corticosteroid treatment. Thus, firm conclusions cannot be derived from the currently available data. Implications for future research, which is required to increase our understanding of potential influences of corticosteroids on the perception of dyspnea, are provided.

Emotions and respiratory function in asthma: a comparison of findings in everyday life and laboratory

OBJECTIVES

The present study examined the influence of emotions on the respiratory function in asthmatic and non-asthmatic individuals in everyday life and the relationship to emotion-induced respiratory changes in the laboratory.

METHODS

Affective states were induced in 10 asthmatic and 10 non-asthmatic participants by viewing affective picture series of either a pleasant, neutral, or unpleasant valence, while airway resistance (Raw) was measured with whole body plethysmography. Following this, individuals measured their mood, forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), physical activity, and medication use for 21 days with an electronic diary, which included a respiratory self-measurement device. Strong pleasant and unpleasant mood episodes were extracted from the diaries and compared with neutral affective states.

RESULTS

Asthmatic patients showed increases of Raw after unpleasant and pleasant emotional stimulation in the laboratory, which was only found after a pleasant stimulation in non-asthmatic participants. In everyday life, no group differences were obtained. Episodes of strong unpleasant mood states were associated with decreases in PEF, whereas in contrast to the laboratory assessment, pleasant mood was associated with increases in PEF. Results for FEV1 were comparable, but non-significant. Physical activity and medication use did not vary systematically between affective episodes. PEF showed no significant relationship with Raw.

CONCLUSIONS

Unpleasant mood is associated with decreased respiratory function in asthmatic patients in everyday life and in laboratory assessments, whereas effects of pleasant mood states are inconsistent. Pulmonary responses to laboratory-induced emotional conditions are not predictive of airways reactivity during daily life.

Inter-session reproducibility of peak expiratory flow with standardized expiratory maneuvers

BACKGROUND

In adults performing forceful expiratory maneuvers, the length of post-inspiratory pause prior to forced expiration may influence the subsequently measured peak expiratory flow (PEF) and increase its variability. We investigated the effects of two different lengths of breath-hold at total lung capacity (TLC) on the short-term reproducibility of PEF in healthy volunteers.

METHODS

Forty-six healthy volunteers (age 34.6+/-8.5; 23 men) performed a series of maximal forceful expirations in two different test sessions, separated by approximately 2 weeks. In each test-session, PEF was measured with two different types of maneuvers. One maneuver (P) included a brief (<2s) post-inspiratory pause at TLC prior to forced expiration, whereas the second maneuver (NP) included no pause at TLC. The speed of inspiration to TLC was fast and similar for both maneuvers. In a given test session, all volunteers performed four efforts for each type of maneuver. The highest PEF for each maneuver was used for analysis. The Bland-Altman statistical analysis was used to determine inter-session reproducibility of PEF.

RESULTS

Within-maneuver analysis of the between-test session reproducibility of PEF showed that neither maneuver systematically biased the measured PEF (mean difference 0.02L/s for the P and 0.17L/s for the NP maneuver). Inter-maneuver between-test session analysis similarly showed that neither maneuver introduced a systematic bias in the maximal PEF (mean difference ranged from -0.15 to -0.01L/s). The limits of agreement were comparable in all maneuver-pair analyses.

CONCLUSIONS

Forceful expiratory maneuvers with or without a brief (<2s) pause at TLC produce comparable PEF values in test-retest sessions.

Continuous noninvasive measurement of pulsus paradoxus complements medical decision making in assessment of acute asthma severity

BACKGROUND

Pulsus paradoxus (PP) is a pathophysiologic parameter that is indicative of asthma severity. The ability of PP to categorize acutely asthmatic patients in accordance with the earlier National Asthma Education and Prevention Program (NAEPP) expert panel report 1 guidelines was determined.

METHODS

An arterial tonometric BP monitor, which was interfaced to an analog-digital converter, executed a periodic amplitude analysis algorithm, which computed PP in real time. The PP measurement was compared to the criterion standard of emergency physicians in determining the hospital admission vs hospital discharge disposition following the NAEPP standardized treatment. Receiver operating characteristics (ROCs) were calculated, and the PP threshold, which maximized sensitivity and specificity, was identified. In a separate laboratory investigation, PP was induced in a healthy volunteer by inspiration through a fixed resistance. Plethysmographic waveform changes, induced by PP, were measured by a second analog-to-digital converter that was connected to a pulse oximeter.

RESULTS

A total of 79 patients were enrolled in the study, of whom 63 met a priori inclusion criteria and had uninterrupted data acquisition. The mean PP for patients who were appropriately discharged from the hospital was 9.1 mm Hg (95% confidence interval [CI], 7.3 to 10.9 mm Hg) and differed from the PP of 17.6 mm Hg (95% CI, 13.5 to 21.8; p < 0.001) for patients admitted to the hospital/relapsed. The sensitivity and specificity for physician disposition were 0.83 and 0.89, respectively, and for PP values were 0.78 and 0.78, respectively. The Wilcoxon area under the ROC curve was 0.82 (95% CI, 0.64 to 0.99) following treatment. The risk ratio was 5.32 for hospital admission among patients with a PP of > 11.3 mm Hg. Changes in the photoplethysmography peak height were correlated to PP from the BP monitor by a regression line with a slope of 0.01 V/mm Hg.

CONCLUSIONS

Continuous PP can aid in determining disposition among emergency department (ED) patients with acute asthma. ED physicians equipped with a PP monitor would be able to objectify the work of breathing and would more closely adhere to NAEPP guidelines. The possibility that a PP detection algorithm could reside in a pulse oximeter warrants further investigation.

Usefulness of monitoring lung function in asthma

There is no firm evidence from randomised controlled trials that routine monitoring of lung function improves asthma control in children. Guidelines for management of asthma consistently recommend routine home monitoring of peak expiratory flow (PEF) in each patient. However, changes in PEF poorly reflect changes in asthma activity, PEF diaries are kept very unreliably, and self management programmes including PEF monitoring are no more effective than programmes solely based on education and symptom monitoring. PEF diaries may still be useful in isolated cases of diagnostic uncertainty, in the identification of exacerbating factors, and in the rare case of children perceiving airways obstruction poorly and exacerbating frequently and severely. If a reliable assessment of airways obstruction in asthma is needed, forced expiratory flow-volume curves are the preferred method. Monitoring of hyperresponsiveness and nitric oxide cannot be recommended for routine use at present. Clinical judgement and expiratory flow-volume loops remain the cornerstone of monitoring asthma in secondary care.

Evaluation of Bronchoalveolar Lavage Fluid Phospholipids and Cytokine Release by Alveolar Macrophages as Prognostic Markers in Sarcoidosis

BACKGROUND

The clinical course of sarcoidosis is unpredictable and reliable laboratory prognostic parameters are lacking.

OBJECTIVES

The aim of the present study was to estimate the prognostic value of bronchoalveolar lavage fluid (BALF) phospholipids and cytokine production by alveolar macrophages (AM) in pulmonary sarcoidosis.

METHODS

We investigated BALF parameters in 64 subjects (55 patients with sarcoidosis and 9 healthy volunteers as controls). After a period of 12 months, the total sarcoidosis study population was divided into three groups according to radiological, functional and laboratory dynamics: the group with a favorable (n = 15), the one with an unfavorable (n = 16) and the one with an intermediate clinical course of the disease (n = 24).

RESULTS

The group of patients with a poor clinical outcome was characterized by a lower percentage of lymphocytes in BALF [20% (4-56%)], rather small amounts of cytokines [TNF-alpha: 1.5 ng/ml/10(6 )(0.08-8.6), IL-6: 5.75 ng/ml/10(6) (1.7-22.5)] and a significant decrease in BALF phospholipids [total lipid phosphorus (TLP): 29.9 micromol/l (13.8-68.3) as compared to 67.5 micromol/l (33.2-127.2) in controls]. Patients with a favorable clinical outcome were shown to have higher lymphocytosis (40%, range 6-64, p < 0.05 versus poor outcome), intensive TNF-alpha and IL-6 release by AM, and close to normal phospholipid content in BALF.

CONCLUSIONS

The level of TNF-alpha secretion by AM <3.9 ng/ml/10(6) and total lipid phosphorus in BALF less than 30 micromol/l may serve as markers of poor prognosis in pulmonary sarcoidosis.

Outpatient monitoring of asthma

Monitoring asthma outcomes is an essential step to the successful implementation of national asthma guidelines. Symptoms, airflow obstruction and exacerbations can be monitored by patients with asthma and by physicians. Patients who practise self-monitoring in conjunction with use of a written action plan and regular medical review have significantly fewer hospitalizations, emergency room visits and lost time from work. Additional monitoring tools are under evaluation, and these include measures of airway responsiveness, airway inflammation, and Internet-based monitoring systems.

The quality of home spirometry in school children with asthma

BACKGROUND

Handheld electronic spirometers provide the opportunity for more comprehensive monitoring of lung function at home than has hitherto been available. The aim of this study was to assess the quality of spirometric data collected at home by 90 asthmatic schoolchildren aged 7-14 years.

METHODS

After training, children carried out twice daily recordings at home for four consecutive periods of 4 weeks using a data storage spirometer (Vitalograph), encouraged by 4-weekly visits from a research nurse. Compliance (proportion of blows recorded at correct time of day), technical quality (by machine criteria), and valid data recorded (the multiple of compliance and technical ability) were assessed.

RESULTS

Mean compliance declined from 81.4% to 70.4% (p<0.001) between the first and last month, although the technical quality of the manoeuvres (81.9% and 80.1%, respectively) did not change significantly (p=0.48).

CONCLUSIONS

There was a steady reduction of valid data over the four periods (from 73.6% to 64.3%, 59.7%, and 57.6%) with wide individual differences. Even under ideal conditions, home spirometry provides an incomplete (and therefore potentially biased) picture of long term changes in pulmonary function.

Monitoring the patient with asthma: an evidence-based approach

The monitoring of symptoms, airflow obstruction, and exacerbations is essential to asthma management. Patients who practice self-monitoring in conjunction with use of a written action plan and regular medical review have significantly fewer hospitalizations, emergency department visits, and lost time from work. Either symptom monitoring or peak expiratory flow monitoring is satisfactory, provided the results are interpreted with reference to the patient's own baseline asthma status. Regular monitoring by physicians also improves health outcomes for patients, provided the physician is systematic and monitors control, medications, and skills at regular intervals. Additional monitoring tools are under evaluation, and these include measures of airway responsiveness, airway inflammation, and Internet-based monitoring systems. Administrators need to monitor the quality and cost of care, as well as compliance with national management guidelines. Assessment of the hospitalization rate and regular audit may achieve these aims in the hospital setting. The best way to assess and monitor asthma in primary care remains an unresolved yet crucial issue because primary care physicians manage the vast burden of illness caused by asthma. Monitoring asthma outcomes is an essential step toward the successful implementation of national guidelines for the management of asthma.

Development of an expert system for the interpretation of serial peak expiratory flow measurements in the diagnosis of occupational asthma. Midlands Thoracic Society Research Group

If asthma is due to work exposures there must be a relation between these exposures and the asthma. Asthma causes airway hyperresponsiveness and obstruction; the obstruction can be measured with portable meters, which usually measure peak expiratory flow, or sometimes forced expiratory volume in 1 second (FEV1). These can be measured serially (for instance 2 hourly) over several weeks at and away from work. Once occupational asthma develops, the asthma will be induced by many non-specific triggers common to non-occupational asthma. The challenge is to identify changes in peak expiratory flow due to work among other non-occupational causes. Standard statistical tests have been found to be insensitive or non-specific, principally because of the variable period for deterioration to occur after exposure, and the sometimes prolonged time for recovery to occur, such that days away from work may initially have lower measurements than days at work. A computer assisted diagnostic aid (Oasys) has been developed to separate occupational from non-occupational causes of airflow obstruction. Oasys-2 is based on a discriminant analysis, and achieved a sensitivity of 75% and a specificity of at least 94%; therefore peak expiratory flow monitoring combined with Oasys-2 analysis is better to confirm than to exclude occupational asthma. A neural network version in development has improved on this. Both have been based on expert interpretation of peak flow measurements plotted as daily maximum, mean, and minimum, with the first reading at work taken as the first reading of the day. Oasys has been evaluated with independent criteria against measurements made in a wide range of occupational situations. Oasys is sufficiently developed to be the initial method for the confirmation, although less so for exclusion of occupational asthma.