Utility of peak expiratory flow monitoring

Association between cooking fuel exposure and respiratory health: Longitudinal evidence from the China Health and Retirement Longitudinal Study (CHARLS)

The epidemiological evidences for the association between cooking fuel exposure and respiratory health were inconsistent, and repeated-measures prospective evaluation of cooking fuel exposure was still lacking. We assessed the longitudinal association of chronic lung disease (CLD) and lung function with cooking fuel types among Chinese adults aged ≥ 40 years. In this prospective, nationwide representative cohort of the China Health and Retirement Longitudinal Study from 2011 to 2018, 9004 participants from 28 provinces in China were included. CLD was identified based on self-reported physician diagnosis in 2018. Lung function was assessed by peak expiratory flow (PEF) in 2011, 2013 and 2015. Multivariable logistic and linear mixed-effects repeated-measures models were conducted to measure the associations of CLD and PEF with cooking fuel types. Three-level mixed-effects model was performed as sensitivity analysis. Among the participants, 3508 and 3548 participants used persistent solid and clean cooking fuels throughout the survey, and 1948 participants who used solid cooking fuels at baseline switched to clean cooking fuels. Use of persistent clean cooking fuels (adjusted odds ratio [aOR] = 0.73, 95 % confidence interval [CI]: 0.61, 0.88) and switch of solid fuels to clean fuels (aOR = 0.81, 95 % CI: 0.67, 0.98) were associated with lower risk of CLD. The use of clean cooking fuels throughout the survey and switch of solid fuels to clean fuels in 2013 were also significantly associated with higher PEF level. Similar results were observed in stratified analyses and different statistical models. The evidence from CHARLS cohort suggested that reducing solid cooking fuel exposure was associated with lower risk of CLD and better lung function. Given the recent evidence, improving household air quality will reduce the burden of chronic lung diseases.

Peak expiratory flow is a reliably household pulmonary function parameter correlates with disease severity and survival of patients with amyotrophic lateral sclerosis

Background

Amyotrophic lateral sclerosis (ALS) is an incurable and fatal neurodegenerative disease; most ALS patients die within 3 to 5 years after symptom onset, usually as a consequence of respiratory failure. In the present study, we aim to screen the survival-related pulmonary function parameters, and to explore the predictive value of peak expiratory flow (PEF) in disease severity and prognosis in patients with ALS.

Methods

The discovery cohort included 202 ALS patients, and the demographic and clinical characteristics of eligible patients were collected and pulmonary function tests were performed using MS-PFT spirometer. In the validation cohort, 62 newly diagnosed ALS patients performed the pulmonary function test by MS-PFT spirometer and household peak flow meter (KOKA) simultaneously.

Results

Among 12 pulmonary function parameters, FVC, FEV1, PEF, MEF75%, and MVV were identified to be independent predictive factors for survival. PEF was highly correlated with FVC (r = 0.797), MVV (r = 0.877), FEV1 (r = 0.847), and MEF75% (r = 0.963). Besides, the values of PEF were positively associated with disease severity (ALSFRS-R score, r_s = 0.539, P < 0.0001), and negatively associated with progression rate (ΔALSFRS-R, r_s = -0.316, P < 0.0001). Finally, we also confirmed that the values of KOKA-measured PEF were highly correlated with the ones measured using MS-PFT spirometer (r = 0.9644, p < 0.0001).

Conclusions

Our work emphasizes the critical role of PFTs in predicting prognosis of ALS patients. PEF is an easily available pulmonary function index, which is also a promising indicator in predicting disease severity and survival for ALS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02635-z.

Asthma

This review provides an evidence-based guide for the diagnosis, evaluation, and treatment of patients with asthma. It addresses typical questions that arise in the clinic-based care of patients with asthma and provides a basic and comprehensive resource for asthma care.

Relationship Between Respiratory Muscle Strength and Conventional Sarcopenic Indices in Young Adults: A Preliminary Study

OBJECTIVE

To investigate the relationships between respiratory muscle strength and conventional sarcopenic indices such as skeletal muscle mass and limb muscle strength.

METHODS

Eighty-nine young adult volunteers who had no history of medical or musculoskeletal disease were enrolled. Skeletal muscle mass was measured by bioelectrical impedance analysis and expressed as a skeletal muscle mass index (SMI). Upper and lower limb muscle strength were evaluated by hand grip strength (HGS) and isometric knee extensor muscle strength, respectively. Peak expiratory flow (PEF), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP) were evaluated using a spirometer to demonstrate respiratory muscle strength. The relationships between respiratory muscle strength and sarcopenic indices were investigated using Pearson correlation coefficients and multiple linear regression analysis adjusted by age, height, and body mass index.

RESULTS

MIP showed positive correlations with SMI (r=0.457 in men, r=0.646 in women; both p<0.01). MIP also correlated with knee extensor strength (p<0.01 in both sexes) and HGS (p<0.05 in men, p<0.01 in women). However, PEF and MEP had no significant correlations with these sarcopenic variables. In multivariate regression analysis, MIP was the only independent factor related to SMI (p<0.01).

CONCLUSION

Among the respiratory muscle strength variables, MIP was the only value associated with skeletal muscle mass.

Daily Peak Expiratory Flow Rate and Disease Instability in Chronic Obstructive Pulmonary Disease

Rationale: Chronic obstructive pulmonary disease, (COPD) is a major cause of morbidity and mortality in the United States. Peak expiratory flow rate (PEFR) monitoring could provide a daily objective measurement of lung function in COPD patients at home. We hypothesized that individuals with greater variability in daily PEFR would signal an unstable patient population with worse outcomes. Methods: This was a retrospective analysis of prospectively collected data using an electronic diary to record daily PEFR and symptoms in severe and very severe COPD patients. Rates of PEFR change were used to characterize patients into stable and unstable groups determined by the distribution of slopes. Exacerbation-free days, time to first hospitalization, hospitalization rate, length of hospitalization, and all-cause mortality were assessed. Results: A total of 104 severe and very severe COPD patients met entry criteria, and were observed for 37,702 patient-days. There were no significant differences in baseline symptoms, demographics, forced expiratory volume in 1 second (FEV₁) or comorbidities between stable versus unstable groups. The unstable group had 34.7 less exacerbation-free days and significantly shorter 6 minute walk distances (6MWD) (227.1 versus 270.7 meters, p=0.031), shorter time to first hospitalization (163 versus 286 days, p=0.017), more frequent hospitalizations (2.6 versus 1.7 per year, p=0.032) and higher all-cause mortality (10.8 versus 5.1%, p= 0.04). Conclusion: Patients with severe to very severe COPD with greater changes in PEFR have shorter 6MWD, reduced time to first hospitalization, more frequent hospitalizations, and higher all-cause mortality despite similar demographic, spirometric and comorbid parameters at baseline. Daily peak flow monitoring can be a useful tool in identifying COPD patients predisposed to worse outcomes.

Control of the lungs via the human brain using neurosurgery

Neurosurgery can alter cardiorespiratory performance via central networks and includes deep brain stimulation (DBS), a routinely employed therapy for movement disorders and chronic pain syndromes. We review the established cardiovascular effects of DBS and the presumed mechanism by which they are produced via the central autonomic network. We then review the respiratory effects of DBS, including modulation of respiratory rate and lung function indices, and the mechanisms via which these may occur. We conclude by highlighting the potential future therapeutic applications of DBS for intractable airway diseases.

Peak flow as a predictor of cause-specific mortality in China: results from a 15-year prospective study of ∼170 000 men

Background Forced expiratory volume in one second (FEV1) is inversely associated with mortality in Western populations, but few studies have assessed the associations of peak expiratory flow (PEF) with subsequent cause-specific mortality, or have used populations in developing countries, including China, for such assessments.

Methods A prospective cohort study followed ∼170 000 Chinese men ranging in age from 40–69 years at baseline (1990–1991) for 15 years. In the study, height-adjusted PEF (h-PEF), which was uncorrelated with height, was calculated by dividing PEF by height. Hazard ratios (HR) for cause-specific mortality and h-PEF, adjusted for age, area of residence, smoking, and education, were calculated through Cox regression analyses.

Results Of the original study population, 7068 men died from respiratory causes (non-neoplastic) and 22 490 died from other causes (including 1591 from lung cancer, 5469 from other cancers, and 10 460 from cardiovascular disease) before reaching the age of 85 years. Respiratory mortality was strongly and inversely associated with h-PEF. For h-PEF ≥ 250 L/min, the association was log-linear, with a hazard ratio (HR) of 1.29 (95% CI: 1.25–1.34) per 100 L/min reduction in h-PEF. The association was stronger but not log-linear for lower values of h-PEF. Mortality from combined other causes was also inversely associated with h-PEF, and the association was log-linear for all values of h-PEF, declining with follow-up, with HRs per 100 L/min reduction in h-PEF of 1.13 (1.10–1.15), 1.08 (1.06–1.11), and 1.06 (1.03–1.08) in three consecutive 5-year follow-up periods. Specifically, lower values of h-PEF were associated with higher mortality from cardiovascular disease and lung cancer, but not from other cancers.

Conclusions A lower value of h-PEF was associated with increased mortality from respiratory and other causes, including lung cancer and cardiovascular disease, but its associations with the other causes of death declined across the follow-up period.

Avaliação do broncoespasmo induzido pelo exercício avaliado pelo Peak Flow Meter em adolescentes obesos

INTRODUÇÃO: Crianças e adolescentes com excesso de peso apresentam maior prevalência de broncoespasmo induzido pelo exercício (BIE), quando comparados a eutróficos. A espirometria e o peak flow meter são importantes métodos avaliativos da função pulmonar. Porém, a aplicabilidade do medidor do pico de fluxo expiratório (peak flow meter) na detecção do BIE em crianças e adolescentes com excesso de peso não é conhecida, o que justifica o desenvolvimento desta pesquisa. OBJETIVOS: Avaliar e comparar o desencadeamento de broncoespasmo induzido pelo exercício (BIE) em crianças e adolescentes não asmáticos com excesso de peso, avaliados pela espirometria e pelo peak flow meter (PFE). CASUÍSTICA E MÉTODOS: Participaram do estudo 39 voluntários acima do percentil 85º (OB) e 30 eutróficos (EU), de oito a 15 anos. A avaliação da função pulmonar pré e pós-teste de broncoprovocação foi realizada pela espirometria e peak flow meter, de acordo com o protocolo de Del Río-Navarro et al., (2000). O BIE foi considerado positivo quando o voluntário apresentou uma redução > 10% do VEF1 basal ou redução > 20% do PFE PFM e/ou PFE E. RESULTADOS: Na detecção do BIE, a prevalência do grupo obeso foi de 26% avaliado pelo peak flow meter (PFEPFM) e 23% pelo VEF1. O tempo do BIE ocorreu nos primeiros 15 minutos pós-exercício em ambos os parâmetros: (PFE PFM) e VEF1. CONCLUSÃO: Os voluntários obesos apresentaram tempo e prevalências similares de BIE, quando avaliados por ambos os métodos de avaliação pulmonar. O fácil manejo e o baixo custo facilitam a maior acessibilidade para a população geral do peak flow meter, o que demonstra sua importância como parte integrante de um programa educacional no diagnóstico inicial do BIE em vias aéreas de grande calibre.

Controlling the Lungs Via the Brain: A Novel Neurosurgical Method to Improve Lung Function in Humans

BACKGROUND:

Deep brain stimulation (DBS) of subcortical brain areas such as the periaqueductal grey and subthalamic nucleus has been shown to alter cardiovascular autonomic performance. The supramedullary circuitry controlling respiratory airways is not well defined and has not been tested in humans.

OBJECTIVE:

To use direct electric stimulation via DBS macroelectrodes to test whether airway resistance could be manipulated by these areas in awake humans.

METHODS:

Thirty-seven patients with in-dwelling deep brain electrodes for movement disorders or chronic pain underwent spirometry according to the European Respiratory Society guidelines. Testing was performed randomly 3 times on stimulation and 3 times off stimulation; patients were blinded to the test. Thoracic diameter changes were measured by a circumferential pressure-sensitive thoracic band. Ten periaqueductal grey and 10 subthalamic nucleus patients were tested. To control for confounding pain and movement disorder relief, the sensory thalamus in 7 patients and globus pallidus interna in 10 patients, respectively, were also tested.

RESULTS:

Peak expiratory flow rate (PEFR) increased significantly with periaqueductal grey and subthalamic nucleus stimulation by up to 14% (P = .02 and .005, respectively, paired-samples Student t tests). Stimulation of control nuclei produced no significant PEFR change. Similarly, changes in thoracic diameter reflecting skeletal activity rather than airway caliber did not correlate with the improvement in PEFR. Forced expiratory volume in 1 second was unchanged by stimulation.

CONCLUSION:

DBS can improve PEFR in chronic pain and movement disorder patients. This finding provides insights into the neural modulation of respiratory performance and may explain some of the subjective benefits of DBS.

Airway obstruction at time of symptoms prompting use of reliever therapy in children with asthma

BACKGROUND

In asthma treatment, doses of inhaled corticosteroids are often adapted to symptoms and need for bronchodilators. However, in cross-sectional studies in emergency room settings, lung function and respiratory symptoms are not always concordant. Available longitudinal data are based on written peak flow diaries, which are unreliable. Using home spirometry, we studied prospectively whether mild respiratory symptoms, prompting reliever therapy are accompanied by a clinically relevant drop in lung function in children with asthma.

METHODS

For 8 weeks, children with asthma scored symptoms and measured peak expiratory flow (PEF) and forced expiratory volume in 1 sec (FEV(1)) on a home spirometer twice daily. Additional measurements were recorded when respiratory symptoms prompted them to use bronchodilators.

RESULTS

The mean difference between symptom free days and at times of symptoms was 6.6% of personal best for PEF (95% CI: 3.2-10.0; p = 0.0004) and 6.0% of predicted for FEV(1) (95% CI: 3.0-9.0; p = 0.0004). There was complete overlap in PEF and FEV(1) distributions between symptom free days and at times of symptoms.

CONCLUSIONS

Although statistically significant, the degree of airway narrowing at times of respiratory symptoms, prompting the use of reliever therapy, is highly variable between patients, limiting the usefulness of home spirometry to monitor childhood asthma.

Is home spirometry useful in diagnosing asthma in children with nonspecific respiratory symptoms?

BACKGROUND

Variation of lung function is considered to be a hallmark of asthma. Although guidelines recommend measuring it as a diagnostic tool for asthma, the usefulness of this approach has not been studied in children.

AIM

To assess the usefulness of home spirometry in children with nonspecific lower respiratory tract symptoms, to diagnose or exclude asthma.

METHODS

In school-aged children, referred by their general practitioner because of chronic respiratory symptoms of unknown origin, the diagnosis of asthma was made or excluded by a pediatric pulmonologist (gold standard), based on international guidelines and a standardized protocol. Additionally, children measured peak expiratory flow (PEF) and forced expiratory flow in 1 sec (FEV(1)) twice daily for 2 weeks on a home spirometer, from which diurnal variation was calculated. These results (index test) were not revealed to the pediatric pulmonologist. The value of home spirometry to diagnose asthma was calculated.

RESULTS

Sixty-one children (27 boys) were included (mean age: 10.4 years; range: 6-16 years). Between asthma and no asthma, the mean difference in PEF variation was 4.4% (95% CI: 0.9-7.9; P = 0.016) and in FEV(1) variation 4.5% (95% CI: 1.6-7.4; P = 0.003). Sensitivity and specificity, based on the 95th-centile of the reference values for PEF and FEV(1) variation (12.3% and 11.8%, respectively) were 50% and 72% for PEF variation and 45% and 92% for FEV(1) variation. The likelihood ratio was 1.8 for PEF and 5.6 for FEV(1).

CONCLUSIONS

The contribution of home spirometry in the diagnostic process for asthma in schoolchildren with nonspecific respiratory symptoms is limited.

Peak flow measurements in children with asthma: what happens at school?

BACKGROUND

Self-monitoring of symptoms or peak flow monitoring (PFM) is recommended for all asthma patients and is commonly included in asthma management plans. Limited data are available documenting PFM outcomes in school settings.

METHOD

Three hundred twenty-three urban children with persistent asthma were enrolled in a school-based study that implemented an internet-based asthma monitoring and data collection system. The mean age of the children was 10.0 (SD 2.1) years; 57% were male and 91% were African American. Children logged in daily to an internet-based program to record their asthma symptoms and PFM reading. Teachers logged in daily to confirm the PFM readings. School staff responsible for student health reported actions taken for low PFM readings.

RESULTS

A total of 12,245 child reports were completed; 98% (n = 11,974) had corresponding teacher reports, confirming the peak flow meter readings reported by the children. The prevalence of reported asthma symptoms varied across PFM readings; the highest prevalence occurred in the setting of red zone readings, with intermediate prevalence in the setting of yellow zone readings, and lowest prevalence in the setting of green zone readings. The actions reported in response to children's symptoms and peak flow results similarly varied; however, instances of no action were reported in the setting of yellow and red zone readings. When comparing the "worst days" of children who had ever had a red or yellow PFM reading with those of children who only had exhibited green, there was a nonsignificant trend toward fewer symptoms in the green-only group. Additionally, there was a nonsignificant trend toward a greater likelihood of being sent to the office or school nurse with greater symptoms in the setting of a yellow or red zone reading.

CONCLUSIONS

On the whole, peak flow readings tended to correspond to asthma disease activity. However, the data indicate that school staff may be more inclined to take action based on their own perceptions of a child's asthma or respond to children's subjective reports of asthma symptoms rather than using a more objective measure of disease activity provided by a peak flow meter.

Reversal of bronchial obstruction with bi-level positive airway pressure and nebulization in patients with acute asthma

Jet nebulization (JN) and non-invasive mechanical ventilation (NIMV) through bi-level pressure is commonly used in emergency and intensive care of patients experiencing an acute exacerbation of asthma. However, a scientific basis for effect of JN coupled with NIMV is unclear. Objective. To evaluate the effect of jet nebulization administered during spontaneous breathing with that of nebulization with NIV at two levels of inspiratory and expiratory pressures resistance in patients experiencing an acute asthmatic episode. Methods. A prospective, randomized controlled study of 36 patients with severe asthma (forced expiratory volume in 1 second [FEV(1)] less than 60% of predicted) selected with a sample of patients who presented to the emergency department. Subjects were randomized into three groups: control group (nebulization with the use of an unpressured mask), experimental group 1 (nebulization and non-invasive positive pressure with inspiratory positive airway pressure [IPAP] = 15 cm H(2)O, and expiratory positive airway pressure [EPAP] = 5 cm H(2)O), and experimental group 2 (nebulization and non-invasive positive pressure with IPAP = 15 cm H(2)O and EPAP = 10 cm H(2)O). Bronchodilators were administered with JN for all groups. Dependent measures were recorded before and after 30 minutes of each intervention and included respiratory rate (RR), heart rate (HR), oxygen saturation (SpO(2)), peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and forced expiratory flow between 25 and 75% (FEF(25-75)). Results. The group E2 showed an increase of the peak expiratory flow (PEF), forced vital capacity (FVC), FEV(1) (p < 0.03) and F(25-75%) (p < 0.000) when compared before and 30 minutes after JN+NIMV. In group E1 the PFE (p < 0.000) reached a significant increase after JN+ NIMV. RR decreased before and after treatment in group E1 only (p = 0.04). Conclusion. Nebulization coupled with NIV in patients with acute asthma has the potential to reduce bronchial obstruction and symptoms secondary to augmented PEF compared with nebulization during spontaneous breathing. In reversing bronchial obstruction, this combination appears to be more efficacious when a low pressure delta is used in combination with a high positive pressure at the end of expiration.

Analysis of longitudinal changes in the psychological status of patients with asthma

Significant relationships between the psychological status and poor asthma outcomes are often reported. However, most of these studies are cross-sectional and none have evaluated how the psychological status progresses over time during the management of asthma patients. Therefore, we examined the longitudinal changes in the psychological status of asthma patients, and compared them with changes in other clinical measurements. Eighty-seven outpatients with stable asthma after 6 months of treatment were enrolled in this study. The psychological status was evaluated using the Hospital Anxiety and Depression Scale (HADS), the health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ). The patient's pulmonary function, peak expiratory flow values and airway hyperresponsiveness were measured at entry and every year thereafter over a 5-year period. Using mixed effects models to estimate the slopes, the HADS anxiety and depression scores did not change significantly over time (p=0.71 and 0.72, respectively). The changes in the HADS scores correlated noticeably with changes in the AQLQ and SGRQ scores, but not with changes in the physiological measurements. The baseline HADS anxiety and depression scores were significantly correlated to the subsequent annual changes in each measurement. The psychological status remained clinically stable over the 5-year study period in patients with stable asthma. Changes in the psychological status were significantly correlated to changes in the health status. The baseline HADS scores were a useful indicator in detecting patients who would show subsequent deterioration in their psychological status.

The validation of work-related self-reported asthma exacerbation

OBJECTIVE

To determine the validity of work-related self-reported exacerbation of asthma using the findings from serial peak expiratory flow (PEF) measurements as the standard.

METHODS

Adults with asthma treated in a health maintenance organisation were asked to conduct serial spirometry testing at home and at work for 3 weeks. Self-reported respiratory symptoms and medication use were recorded in two ways: a daily log completed concurrently with the serial PEF testing and a telephone questionnaire administered after the PEF testing. Three researchers evaluated the serial PEF records and judged whether a work relationship was evident.

RESULTS

95 of 382 (25%) working adults with asthma provided adequate serial PEF data, and 13 of 95 (14%) were judged to have workplace exacerbation of asthma (WEA) based on these data. Self-reported concurrent medication use was the most valid single operational definition, with a sensitivity of 62% and a specificity of 65%.

CONCLUSIONS

A work-related pattern of self-reported asthma symptoms or medication use was usually not corroborated by serial PEF testing and failed to identify many people who had evidence of WEA based on the serial PEF measurements.

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.

A randomized clinical trial of peak flow versus symptom monitoring in older adults with asthma

OBJECTIVE

To determine whether peak flow monitoring has value above and beyond symptom monitoring when used as part of an asthma management plan.

METHODS

From a large managed-care organization, 296 adults, aged 50-92 yr, were recruited and randomly assigned in equal numbers to either use of symptoms or peak flow rate (twice daily or "as needed") for asthma monitoring, and monitored every 6 mo for 2 yr. Interventions were delivered in four 90-min small-group classes and included a personalized action plan and coaching in proper use of asthma inhalers.

RESULTS

We found no significant differences between peak flow rate and symptom monitoring, or between twice-daily and as-needed peak flow monitoring in the primary or secondary study outcomes: health care utilization (acute, nonacute, or total asthma visits), Asthma Quality-of-Life Questionnaire (AQLQ) scores, and lung function. AQLQ scores and prebronchodilator FEV1 increased significantly for both groups between baseline and 6 mo (AQLQ: mean, 0.4 units; 95% confidence interval, 0.3, 0.5; p < 0.0001; FEV1% predicted: mean, 4%). Inhaler technique improved substantially in both groups.

CONCLUSIONS

Peak flow monitoring has no advantage over symptom monitoring as an asthma management strategy for older adults with moderate-severe asthma when used in a comprehensive asthma management program. Improved outcomes in both groups suggest that understanding proper medication use, regular monitoring of asthma status, and understanding how to respond to changes are of primary importance.

Expiratory Flow Maneuvers in Patients with Neuromuscular Diseases

OBJECTIVES

To compare cough peak flows (CPF), peak expiratory flows (PEF), and potentially confounding flows obtained by lip and tongue propulsion (dart flows, DF) for normal subjects and for patients with neuromuscular disease/restrictive pulmonary syndrome and to correlate them with vital capacity and maximum insufflation capacity.

DESIGN

A cross-sectional analytic study of 125 stable patients and 52 normal subjects in which CPF, PEF, and DF were measured by peak flow meter and vital capacity and maximum insufflation capacity by spirometer.

RESULTS

In normal subjects and in patients, the DF significantly exceeded PEF and CPF (P < or = 0.001). For normal subjects, PEF and CPF were not significantly different. For patients with neuromuscular disease/restrictive pulmonary syndrome, the CPF significantly exceeded PEF (P < 0.05). No normal subjects but 14 patients had DF lower than CPF. Thirteen of these 14 had the ability to air stack (maximum insufflation capacity greater than vital capacity), indicating greater compromise of mouth and lip than of glottic muscles. For 14 of 88 patients, maximum insufflation capacity values did not exceed vital capacity, mostly because of inability to close the glottis (inability to air stack). Nonetheless, for 11 of these 14 patients, the DF were within a standard deviation of the whole patient group; thus, bulbar-innervated muscle dysfunction was not uniform. CPF and PEF correlated with vital capacity (r = 0.85 and 0.86, respectively), and with maximum insufflation capacity (r = 0.76 and 0.72, respectively).

CONCLUSIONS

Measurements of CPF, PEF, and DF are useful for assessing bulbar-innervated, inspiratory, and expiratory muscle function. Care must be taken to not confuse them.

Efficacy and tolerability of budesonide Clickhaler and Turbuhaler in adult asthma

New dry powder inhalers should be clinically comparable with established devices to ensure the continuity of effective therapy for asthma patients. This randomized, open, parallel group study compared the clinical efficacy and tolerability of budesonide delivered via Clickhaler or Turbuhaler dry powder inhalers in adults with mild to moderate stable asthma. Following a 4-week stabilizing period using budesonide Turbuhaler adults aged 18 years or older, who had been treated with inhaled corticosteroids for at least the previous 12 weeks, were randomized to receive budesonide twice daily (<or=1600 microg/day) via either Clickhaler (n=110) or Turbuhaler (n=112) for 12 weeks. Morning peak expiratory flow (PEF), evening PEF, asthma symptoms, and use of inhaled short-acting beta2-agonist were recorded daily by the patients on diary cards. Lung function and tolerability data were recorded at clinic visits following 4, 8, and 12 weeks' treatment. Efficacy was measured primarily by mean change from the run-in baseline in weekly morning PEF. Of the 222 patients randomized to treatment, 167 completed the study according to the protocol. Repeated-measures analysis of covariance indicated that the devices were clinically equivalent; a treatment difference of--2.3 L/min separated the group mean changes in weekly morning PEF (95% confidence interval--7.9 to 3.3). Secondary analyses also supported clinical comparability. This study demonstrates the comparable clinical efficacy and tolerability of budesonide Clickhaler and Turbuhaler devices in adult patients with stable asthma.

Longitudinal changes in patient vs. physician-based outcome measures did not significantly correlate in asthma

BACKGROUND AND OBJECTIVE

Although improving health status is one important aim in managing asthmatic patients, few studies have evaluated their health status longitudinally. Therefore, we examined longitudinal changes in health status of asthma patients, and compared them with changes in physiological measures.

METHODS

Eighty-seven outpatients with stable asthma after 6 months of treatment were recruited. Health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ), pulmonary function, peak expiratory flow (PEF) values, and airway hyperresponsiveness (AHR) were evaluated at entry and every year over a 5-year period.

RESULTS

Using mixed effects models to estimate the slopes, the overall AQLQ score declined statistically at a mean rate of 0.06 units/year (P=.0091). However, this decline did not reach a clinically significant level at 5 years. The total SGRQ score did not change significantly (P=.54). Although the forced expiratory volume in 1 sec declined at a mean rate of 53 mL/year, the PEF variability and AHR improved significantly.

CONCLUSION

Health status was clinically stable over the 5-year study period in patients with asthma, which contrasted with the changes in the physiological outcome measures. As a patient centered outcome measure, health status should be followed separately.

Monitoring response to treatment in asthma management: food for thought

Asthma is a chronic inflammatory disorder of the airways that is characterized by episodic symptoms. In this regard, asthma management has classically involved periodic re-assessment by the health-care provider, during which therapy is altered mainly based on clinical and physiological parameters, such as assessment of symptoms, spirometry and peak expiratory flow monitoring. In this context, various markers of airway inflammation (e.g. eosinophils in the induced sputum, nitric oxide in the exhaled air) have been proposed to assess the severity of asthma and to adjust the therapy accordingly. The evaluation of airway hyper-responsiveness with different stimuli has also been suggested as a new tool to monitor asthma. However, the lack of definite relationships between airway inflammation and asthmatic symptoms strongly limit the use of markers of asthma severity in the clinical setting. Therefore, the need of new tools to assess the severity of asthma is raised. The ideal measurement employed to establish the proper asthmatic therapy should be safe, non-invasive, easy to perform, reproducible and accurate, and have the capability to monitor the changes induced by the therapeutic interventions. A careful review of the available techniques, and the evaluation of their sensitivity and specificity in the clinical setting is warranted.

Assessing symptoms and peak expiratory flow rate as predictors of asthma exacerbations

OBJECTIVE

To investigate peak expiratory flow rate (PEFR) and quality of life scores for their ability to predict exacerbations of asthma.

PARTICIPANTS AND METHODS

We identified adults who received oral or inhaled asthma medications from 36 community drugstores. We administered the McMaster Asthma Quality of Life Questionnaire (AQLQ) and measured PEFR, defining "red zone" (highest risk) as a PEFR < 50% of each patient's expected value based on gender, age, and height. We identified asthma exacerbations (breathing-related emergency department visits and hospitalizations) within 4 and 12 months after enrollment and used proportional hazards regression to assess the ability of PEFR and AQLQ scores to predict exacerbations, controlling for clinical and demographic factors.

RESULTS

A red zone PEFR was a significant univariable predictor of exacerbations within 12 months (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.1 to 3.0; P =.027). However, neither a red zone PEFR, the raw PEFR, or percent of predicted maximal PEFR were significantly predictive when controlling for AQLQ scores, clinical characteristics, or demographic data (P >.2). However, the 4 subscales of the AQLQ were each significant univariable and multivariable predictors of asthma exacerbations. For example, the overall AQLQ scale had a multivariable HR of 0.63 (95% CI, 0.46 to 0.87; P =.005) for exacerbations occurring within 4 months and 0.66 (95% CI, 0.54 to 0.82; P <.001) within 12 months.

CONCLUSIONS

PEFR added no predictive information to that contained in AQLQ scores and clinical and demographic data. These results support the National Institutes of Health asthma guidelines' recommendation for routinely assessing symptoms but not PEFR.

Tolerability of carvedilol in patients with heart failure and concomitant chronic obstructive pulmonary disease or asthma

BACKGROUND

A substantial proportion of the population with congestive heart failure (CHF) has concomitant airway disease. Little information exists on the tolerability of carvedilol in patients with chronic obstructive pulmonary disease (COPD). In this study, we assessed the tolerability and efficacy of carvedilol in patients with CHF and concomitant COPD or asthma.

METHODS

Between 1996 and 2000, a total of 487 patients began receiving open-label carvedilol. Forty-three (9%) had COPD (n = 31) or asthma (n = 12). Spirometry supported clinical diagnosis in all, and full pulmonary function testing supported diagnosis in 71%. Sixty percent began carvedilol therapy in the hospital and underwent measurement of peak expiratory flow rates (PEFR) before and after dosing.

RESULTS

In patients with COPD, mean forced expiratory volume in one second (FEV(1)) was 62% +/- 13% predicted, reversibility was 4% +/- 4% with bronchodilators, and FEV(1)/FVC was 62% +/- 8%. Mean PEFR was 325 +/- 115 liter/min before the dose and increased by 17% 2 hours after the carvedilol dose (p = 0.04). In patients with asthma, mean FEV(1) was 80% +/- 17% predicted, reversibility was 13% +/- 7%, and FEV(1)/FVC was 74% +/- 11%. Mean PEFR was 407 +/- 161 liter/min before the dose with no significant change 2 hours after the dose. Carvedilol was introduced safely in 84% of patients with COPD, with only 1 patient withdrawn from therapy for wheezing. In contrast, only 50% of patients with asthma tolerated carvedilol. Survival at 2.5 years was 72%. In survivors, left ventricular end-diastolic diameter decreased from 76 +/- 11 mm to 72 +/- 14 mm (p = 0.01), left ventricular end-systolic diameter decreased from 65 +/- 13 mm to 60 +/- 15 mm (p = 0.01), and fractional shortening increased from 14% +/- 7% to 17% +/- 7% (p = 0.05) at 12 months.

CONCLUSIONS

Patients with CHF and COPD tolerated carvedilol well with no significant reversible airflow limitation, but patients with CHF and asthma tolerated carvedilol poorly. The effect of carvedilol on left ventricular dimensions and function in patients with concomitant airway diseases was similar to that seen in our general group of patients. Asthma remains a contraindication to beta-blockade.

The effects of aerial spraying with Bacillus thuringiensis Kurstaki on children with asthma

OBJECTIVE

To determine if aerially spraying a biological pesticide was associated with an increase in the symptoms or change in the Peak Expiratory Flow Rate of children with asthma.

METHODS

A pre/post matched pairs cohort design was used. Children living in the spray zone were matched with children outside of the spray zone. Peak Expiratory Flow Rates, asthma symptoms and non-asthma symptoms were recorded in diaries.

RESULTS

There were no differences in asthma symptom scores between subjects and controls, neither before nor after the spray; nor were there significant changes in Peak Expiratory Flow Rates for subjects after the spray period.

CONCLUSIONS

No evidence of adverse effects from the use of the biological pesticide was found. We believe that this is the first paper to address the issue of whether or not aerial spraying with Btk has a harmful effect on children with asthma.

Is home peak expiratory flow monitoring effective for controlling asthma symptoms?

A case in which a home peak expiratory flow (PEF) monitoring device was recommended led us to review the evidence examining this intervention. The clinical question to be answered was: should these devices be consistently recommended to all patients with asthma? A comprehensive search revealed eight randomized controlled trials, one review and one consensus report. Four trials provided all subjects with asthma education and compared patient-specific action plans based on symptoms to those based on PEF readings. Four trials compared usual asthma care to peak flow monitoring (PFM) and varied in both their content and intensity of asthma education. Six out of eight studies showed improvement in some selected markers of asthma morbidity with home PFM-based action plans. Improvements were also observed in patients using a symptom-based action plan. These studies did not demonstrate any obvious advantage of PFM compared with symptom-based monitoring but did suggest that a monitoring plan with predetermined actions based on PEF measurements or symptoms can lead to improved asthma control. Although not specifically studied, PFM may be more appropriate and effective for patients who have difficulty identifying worsening of asthma control through symptom monitoring.

Assessing respiratory status from a distance

Home care professionals are increasingly required to manage patients with chronic respiratory conditions. Under PPS, an even stronger mandate requires that every intervention be timely, necessary, valuable, cost effective, and lead to positive patient outcomes. This article focuses on the cost benefits, tools, and interventions available that enhance the ability to assess respiratory status "from a distance."

Comparisons of peak diurnal expiratory flow variation, postbronchodilator FEV(1) responses, and methacholine inhalation challenges in the evaluation of suspected asthma

STUDY OBJECTIVES

The validity of peak expiratory flow variation (PEFvar) as defined by National Heart, Lung, and Blood Institute (NHLBI) guidelines as a diagnostic tool for suspected asthma or its comparative value to methacholine inhalation challenge (MIC) or postbronchodilator (BD) FEV(1) responses has not been formally assessed. We prospectively analyzed the correlation of 28 different PEFvar indexes (including 4 NHLBI-compatible indexes) with MIC and pre-BD and post-BD FEV(1) responses in suspected asthmatic subjects with normal findings on lung examination, chest radiography, and baseline spirometry.

DESIGN

Participants were asked to record peak expiratory flow four times daily for 2 to 3 weeks, followed by an MIC. During a minimum 6-month follow-up period, a clinical diagnosis of asthma was made or ruled out based on testing results and response to antiasthma therapy.

SETTING

Medical school-affiliated subspecialty private practice of allergy, asthma, and immunology.

PARTICIPANTS

One hundred twenty-one suspected asthmatic patients with normal findings on lung examination, chest radiography, and baseline spirometry.

MEASUREMENTS AND RESULTS

Fifty-seven subjects completed both the peak flow diary and the MIC and were accepted for statistical analysis. There were no statistically significant correlations between any peak expiratory flow index and MIC. Among the three diagnostic tools evaluated, MIC had the highest sensitivity (85.71%). All the PEFvar indexes and post-BD responses had low sensitivity and high false-negative rates.

CONCLUSIONS

PEFvar and post-BD FEV(1) responses are poor substitutes for MIC in the assessment of patients with suspected asthma with normal findings on lung examination, chest radiography, and spirometry. Our findings warrant a reconsideration of the NHLBI guidelines recommendation of the utility of PEFvar as a diagnostic tool for asthma in clinical practice.

Asma aguda em adultos na sala de emergência: o manejo clínico na primeira hora

Asma é doença com alta prevalência em nosso meio e ao redor do mundo. Embora novas opções terapêuticas tenham sido recentemente desenvolvidas, parece haver aumento mundial na sua morbidade e mortalidade. Em muitas instituições, as exacerbações asmáticas ainda constituem emergência médica muito comum. As evidências têm demonstrado que a primeira hora no manejo da asma aguda na sala de emergência concentra decisões cruciais que podem determinar o desfecho desta situação clínica. Nesta revisão não-sistemática, os autores enfocaram a primeira hora da avaliação e tratamento do paciente com asma aguda na sala de emergência, descrevendo uma estratégia apropriada para o seu manejo. São consideradas as seguintes etapas: diagnóstico, avaliação da gravidade, tratamento farmacológico, avaliação das complicações e decisão sobre onde se realizará o tratamento adicional. Espera-se que estas recomendações contribuam para que o médico clínico tome a decisão apropriada na primeira hora do manejo da asma aguda.

Endogenous circadian rhythm of pulmonary function in healthy humans

Numerous studies have demonstrated a diurnal rhythm in indices of pulmonary function in both healthy subjects and subjects with asthma, with minima occurring during the night. To determine whether such diurnal changes are caused by an endogenous circadian rhythm or by diurnal alterations in behavior or the environment, we measured indices of pulmonary function throughout a "constant routine" protocol designed to unmask underlying circadian rhythms. After two acclimation days in the laboratory, 10 healthy adults maintained relaxed wakefulness in a semirecumbent posture in a constant environment with low light (10 lux) for 41 h. Measurements of FEV(1), FEVC, PEF, blood cortisol, and core body temperature (CBT) were performed every 2 h. Results of cosinor analysis of group data aligned to CBT circadian minimum revealed significant circadian variations in FEV(1) and FEV(1)/FEVC, cortisol, and CBT, and lack of significant circadian variations in FEVC and PEF. The ranges (peak to trough) of mean circadian changes in spirometric variables were 2. 0-3.2% of the mesor. The circadian minima of all variables occurred within the usual sleep period (although subjects remained awake). Because of differences in phase relationships between CBT and pulmonary function among subjects, the circadian rhythms within subjects were generally larger than the group average circadian changes, being significant for FEV(1)/FEVC in 5 of 10 subjects and for PEF in 6 of 10 subjects. Sleep deprivation (24 h) failed to cause a significant change in any pulmonary function variable (when controlled for circadian phase). Thus, endogenous circadian rhythms contribute to diurnal changes in pulmonary function in healthy subjects.

Influence of peak expiratory flow monitoring on an asthma self-management education programme

We assessed whether peak expiratory flow monitoring added to a self-management education programme reduced morbidity and improved pulmonary function and adherence to treatment in 100 asthma patients (aged 17-65 years) with adequate treatment and regular 1-year follow-up. Patients randomized to the experimental group used peak expiratory flow readings as the basis for their therapeutic plan coupled with educational intervention, whereas patients in the control group received the same educational intervention and used symptoms only to guide self-management. Morbidity parameters, functional status and adherence to medical regimens improved in both groups, although the percentage of patients with satisfactory adherence was significantly better in the group with peak expiratory flow monitoring (83%) than in controls (52%) (P = 0.05). The multivariate analysis showed that severity of asthma (odds ratio 9.28, 95% confidence interval 1.87-45.96, P = 0.006 for moderate asthma) and type of self-management education programme (odds ratio: 6.19; 95% confidence interval: 2.04-18.81; P = 0.001 for the use of peak expiratory flow readings) were the only independent predictors of adherence to treatment. However, a statistically significant association between adherence and use of peak expiratory flow monitoring was only found in patients with moderate asthma (P = 0.0009). We conclude that peak expiratory flow monitorization in optimal conditions (adequate medical regimen, individualized self-management education and regular follow-up) showed a beneficial effect on adherence to prescribed regimens only in patients with moderate asthma.

Differential diagnosis of chronic airflow obstruction

Chronic obstructive pulmonary disease is a syndrome including illnesses such as asthma, chronic bronchitis, and emphysema. Although these diseases share a common obstructive component, their optimal treatment and prognosis differ. This article examines the salient features of the history, physical exam, pulmonary function tests, and radiological evaluation which may allow the clinician to differentiate the various diseases that make up COPD; thus allowing the clinician to better target the multiple therapeutic modalities available.