Peak Expiratory Flow Rate Monitoring Research Articles

The diagnostic accuracy of spirometry versus peak expiratory flow test for follow-up of adult asthma patients at primary care level.

Background: The asthma burden is growing worldwide, and this is predisposed by environmental and occupational exposures as well as individual risk factors. This study was aimed at a comparison of diagnostic accuracy of spirometry and peak expiratory flow rate (PEFR) in asthma screening of adult patients with lung function abnormalities that present at the level of primary care. Methods: This study was conducted in Shymkent city, South Kazakhstan, the third most populous city of the country with developed industries and high rates of pulmonary diseases. Four hundred and ninety-five adult patients with lung function abnormalities were enrolled in the study and underwent two screening tests (spirometry and PEFR). The diagnosis of asthma was verified by a qualified pulmonologist after performance of screening tests and was based on symptoms, medical history, and laboratory and lung function tests. Results: The sensitivity of spirometry was 0.97 and that of PEFR was 0.95 (p = 0.721), whereas the specificity of spirometry was 0.37 and that of PEFR was 0.28 (p = 0.227). Both tests yielded the same results for the positive predictive value (0.98). The negative predictive value was significantly higher for spirometry versus PEFR (0.23 versus 0.08; p = 0.006). The positive and negative likelihood ratios of the two tests also differed significantly (p = 0.001 and p = 0.006, respectively), whereas the overall accuracy was comparable between the two tests (0.96 for spirometry and 0.94 for PEFR; p = 0.748). Conclusion: Ambulatory PEFR monitoring is non-inferior to the monitoring of the forced expiratory volume in 1 second and could be used for screening purposes on equal grounds with spirometry.

The diagnosis of occupational asthma confirmed by serial peak expiratory flow rate monitoring

Abstract Occupational asthma, the most common occupational respiratory disease in industrialized societies, accounts for 5-10% of all cases of asthma diagnosed in the world. The number of cases is increasing given the development of the “consumer society”. We aim to discuss a case of occupational asthma that we have confirmed using internationally validated methods.

How to use peak expiratory flow rate

Asthma is the most common chronic disease of children worldwide.1 The most recent National Institute for Health and Care Excellence asthma guidelines explicitly state that asthma should not be diagnosed...

Occupational asthma due to spruce wood

Workers exposed to a variety of wood dusts are known to experience work-related respiratory symptoms, including occupational asthma. There are, however, few reports of occupational asthma due to spruce wood. We present the case of a 31-year-old sawmill owner with severe asthma caused by exposure to spruce wood dust, who developed asthmatic symptoms after 2 years of working. Investigations included clinical examination, routine laboratory tests, spirometry, chest X-ray, total serum immunoglobulin E (IgE) and specific serum IgEs against various woods and other occupational allergens. Additionally, we monitored the peak expiratory flow rate (PEFR) and symptom score both at work and when off work. Specific serum IgE for spruce wood was detected (7.8 IU/ml). The results of PEFR and workplace symptom-score monitoring, coupled with an elevated eosinophil count in induced sputum, supported the diagnosis of occupational asthma. To our knowledge, this is the first well-documented case of occupational asthma induced by spruce wood dust. A type I immunological mechanism seems to be responsible.

Adherence with a Hand-Held Electronic Device versus Conventional Peak Expiratory Flow Rate Monitoring in Children with Asthma

Peak flow monitoring is recommended by the National Heart, Lung and Blood Institute once daily for patients with moderate to severe persistent asthma. Previous studies have shown suboptimal adherence to peak flow monitoring and therefore the utility of peak flows has been questioned. Our objective was to perform a prospective study examining adherence of pediatric patients to peak expiratory flow rate (PEFR) monitoring with a device that measures peak flow and forced expiratory volume in 1 second (FEV1) at home (AirWatch®, (iMetrikus, Inc., Carlsbad, CA) versus standard peak flow monitoring (ASSESS® peak flow meter, Respironics, Cedar Grove, NJ) and to determine if home FEV1 monitoring offered an advantage over peak flow. Thirty-nine patients, age 6 to 17 years with moderate to severe persistent asthma were enrolled in an 8-month crossover study. The study consisted of four phases: a 2-month phase 1 to assess compliance; 4-month long crossover phases 2 and 3 when patients used either ASSESS® or AirWatch®, and a 2-month phase 4 when all patients used AirWatch®. Patients who were compliant with AirWatch® and PEFR recording during phase 1 were randomized to either AirWatch® or daily ASSESS® peak flow. Patients sent AirWatch® data by modem at least once per month. Assess® data was collected on a monthly basis from the patient’s diary. Patients using AirWatch® performed at least one peak flow approximately 77% of the days during the study period. Patients using ASSESS® reported that they performed one or more peak flows on 93% of the days. AirWatch® predicted exacerbations of asthma 55% of the time versus ASSESS® 50% of episodes. Most patients (87.5%) preferred AirWatch®. Overall adherence with once daily peak flows occurred over 75% of the time for patients using either device. There was no difference between standard ASSESS® peak flow meter and AirWatch® in predicting exacerbations, although most patients preferred AirWatch®. (Pediatr Asthma Allergy Immunol 2006; 19[2]:118–125.)

A Preliminary Study of PEFR Monitoring in Patients with Chronic Cough

It is important to make a differential diagnosis of cough variant asthma in patients with chronic cough. To examine whether or not peak expiratory flow rate (PEFR) is useful for the differential diagnosis of cough variant asthma in such patients, diurnal variation rates of PEFR were calculated in 23 patients who presented with dry cough lasting four or more weeks and who showed no abnormalities on chest radiographs. None of the patients had wheezes, and pulmonary function testing at the time of visit to the hospital revealed no abnormalities. During the control period, the mean diurnal variation rate of PEFR in 23 patients was 16.3 +/- 7.9%. Six, nine and eight patients had PEFR diurnal variations rates of <10% (Group 1), 10-19% (Group 2), and > or = 20% (Group 3), respectively. At week 3 of treatment with bronchodilators, only Group 3 showed a significant decrease in PEFR diurnal variation rate from 25.7% to 10.1%. The cough score decreased significantly in Group 3 only. These patients had enhanced bronchial hyperresponsiveness and showed eosinophils in induced sputum, leading to the diagnosis of cough variant asthma (CVA). After making the diagnosis of CVA, an inhaled corticosteroid or a Th2 cytokine production inhibitor suplatast tosilate was administered to patients; consequently, they showed no recurrence of cough. PEFR monitoring allowed the detection of morning dip and was suggested to be potentially useful for the differential diagnosis of cough variant asthma in patients with chronic cough.

Time-Between Control Charts for Monitoring Asthma Attacks

The monitoring of peak expiratory flow rate (PEFR) is crucial for effective management of asthma. Daily PEFR monitoring is recommended, yet the data are rarely used by patients to help them understand their progress or by clinicians to modify treatment plans. Time-between control charts, which have been shown to be specially suited for monitoring rare events, can be used to monitor asthma attacks. Each patient is asked to record his or her PEFR value once a day, and these data are used to construct the control chart. PEFR data for three previously reported cases are presented and used to illustrate the control chart methodology. If duration of consecutive attacks is plotted and the observed duration exceeds the upper control limit (UCL), the patient is getting worse. If length of consecutive symptom-free days is plotted and the observed duration exceeds the UCL, the patient is getting better. In both circumstances, the clinician and the patient explore what brought about the prolonged recovery or periods of deterioration. The object is to increase time until the next attack. Using time-between control charts in monitoring asthma attacks has the advantage of providing a visual display of data that, unlike eyeballing of trends, clarifies when patients should seek additional clinical advice. The control limit allows clinicians and patients to ignore random variations and focus on real changes in underlying patterns of asthma attacks.

Use of pulmonary function tests in the diagnosis of occupational asthma

To discuss the different methods of assessing lung function measurements for the diagnosis of occupational asthma, focusing in particular on serial peak expiratory flow rate (PEFR) monitoring, including details on how PEFR records should be kept, plotted, and analyzed and limitations of the method. Published studies on the use of diagnostic methods in occupational asthma, expert opinion, and recently obtained data from studies performed at a large occupational lung disease clinic. STUDY SOURCES: The expert opinion of the author was used to select the relevant data for review. Objective methods are necessary for the diagnosis of occupational asthma, since clinical history alone is not a satisfactory means of diagnosis. Serial PEFR monitoring has a high diagnostic sensitivity and specificity for occupational asthma and is more useful than evaluation of cross-shift change in forced expiratory volume in 1 second or change in nonspecific bronchial hyperresponsiveness. Interpretation is best performed by expert visual evaluation of plots of maximum, mean, and minimum daily PEFR readings. Despite some limitations of the method, serial PEFR monitoring is usually the most appropriate first-line investigation in workers suspected of having occupational asthma.

Children's Self‐Reports of Characteristics of Their Asthma Episodes

Our purpose was to examine school‐age children's self‐reports of characteristics of their asthma episodes including the precipitating events, symptoms experienced during the episodes, and interventions used to resolve the episodes. Children's self‐reports of their asthma episodes were assessed over a 6‐week period for 42 children with persistent asthma who participated in a randomized, controlled clinical trial to evaluate the efficacy of an asthma self‐management program on adherence to recommended daily peak expiratory flow rate monitoring. Children were instructed to answer the following questions on the Asthma Report Form each time they experienced an asthma episode: 1) What were you doing; 2) How did you feel; and 3) What did you do to help your breathing? Of the children, 71% experienced at least one asthma episode during the 6 weeks. There were a total of 206 episodes. Physical activity (51%) was the most cited trigger, cough alone or combined with other symptoms (84%) was the predominant symptom, and rescue asthma medication (59%) was identified most often as the intervention used by the children to resolve the asthma episode. Children's self‐reports provided valuable information about their asthma episodes. The finding that most of the children experienced at least one asthma episode during the 6‐week period underscores the importance of family education on how to handle asthma episodes effectively at home. Because physical activity was cited most often as a trigger for asthma episodes, families should receive education on preventive steps for averting an asthma episode prior to the child engaging in physical activity.

Symptom monitoring in childhood asthma: a randomized clinical trial comparing peak expiratory flow rate with symptom monitoring

Accurate symptom evaluation is a critical component of asthma management. Limited data are available about the accuracy of symptom evaluation by children with asthma and their parents, or the impact of various symptom-monitoring strategies on asthma morbidity outcomes. The purpose of this randomized clinical trial was to evaluate the effect of three different intensities of symptom monitoring on asthma morbidity outcomes. One hundred sixty-eight children (ages 6 to 19) of diverse racial, geographic, and socioeconomic backgrounds were randomized to 1 of 3 treatment groups (subjective symptom evaluation, symptom-time peak expiratory flow rate (PEFR) monitoring, daily PEFR monitoring) in this longitudinal, clinical trial. Outcome measures included a summary asthma severity score, forced expiratory volume in 1 second, symptom days, and health care utilization. Children who used PEFR meters (PFMs) when symptomatic had a lower asthma severity score, fewer symptom days, and less health care utilization than children in the other two treatment groups. Minority and poor children had the greatest amount of improvement using PFMs when symptomatic. Results were much less striking in white families. Thirty percent of families in the PFM treatment groups discontinued use entirely by 1 year postexit, whereas the majority of families who continued use (94%) used them only when symptomatic to inform symptom interpretation and management decisions. Not every child with asthma needs a PFM. Children and families facing extra challenges as a result of illness severity, sociodemographic, or health care system characteristics clearly benefited most from PFM use.

Glutaraldehyde: an occupational hazard in the hospital setting.

We report a series of 24 health-care workers with respiratory symptoms suggestive of occupational asthma due to glutaraldehyde exposure. The history of asthmatic symptoms was investigated with peak expiratory flow rate (PEFR) monitoring, and in eight of the subjects, the specific bronchial provocation test (SBPT) was applied as reference standard for diagnosis of occupational asthma. Levels of glutaraldehyde were monitored in the challenge chamber during the SBPT. Work environmental levels of glutaraldehyde were measured from air samples collected at least once during the PEFR monitoring of endoscopy and theatre nurses. Specific IgE antibodies to glutaraldehyde were measured with a series of glutaraldehyde modified proteins. In the eight workers who underwent SBPT, the diagnosis of occupational asthma was confirmed by a positive reaction (late and dual reaction in five and in three subjects, respectively). The mean level of glutaraldehyde observed during the challenge tests was 0.075 mg/m3 (range 0.065-0.084 mg/m3). In 13 out of the 16 remaining workers, the serial PEFR monitoring showed a work-related effect. In three workers, there was no physiological confirmation of occupational asthma. Levels of glutaraldehyde from the air samples collected in the workplace were as follows: personal short-term samples (mean 0.208 mg/m3; median 0.14 mg/m3; range 0.06-0.84 mg/m3), personal long-term samples (mean 0.071 mg/m3; median 0.07 mg/m3; range 0.003-0.28 mg/m3). Measurements of specific IgE antibodies to glutaraldehyde-modified proteins were positive in seven patients (29.1%) according to a cutoff value of 0.88% RAST binding. The presence of atopy to common environmental allergens and smoking was not associated with specific IgE positivity (P>0.05; Fisher's exact test). Our report indicates the importance of glutaraldehyde as an occupational hazard among exposed health-care workers. Intervention in the workplace, training of personnel handling this chemical, and accurate health surveillance may reduce the risk of developing occupational asthma due to glutaraldehyde.

Using Statistical Process Control Charts for the Continual Improvement of Asthma Care

Home monitoring of lung function using simple, inexpensive tools to measure peak expiratory flow rate (PEFR) has been possible since the 1970s. Yet although current national and international guidelines recommend monitoring of PEFRs via traditional run charts, their use by both patients and physicians remains low. The role of statistical process control (SPC) theory and charts in the serial monitoring of lung function at home were explored and applied to the direct care of patients with asthma. The method represents an integration of collective professional and improvement knowledge with the related disciplines of continual improvement, SPC, system thinking/system dynamics, paradigms, and the learning community/organization. Use of PEFR control charts for four patients cared for at the Asthma-Allergy Clinic and Research Center (Shreveport, La) is described. The key to good asthma control is the ability to optimize lung function by reducing the variation between serial lung function measurements and thereby generate a safe range of function. Knowledge of the type of variation (special cause or common cause) in the system helps in focusing clinical decision making. Case 4, an 11-year-old boy, for example, shows how control charts were used to learn the effects of a new inhaled corticosteroid. Comparison of the last 14 days of baseline and the last 14 days of open label use of the inhaled corticosteroid showed an obvious improvement in actual PEFR values--which a run chart or comparison of means would have easily demonstrated. The control chart showed that this child's care process at baseline was functionally at risk for severe asthma (46% personal best) and that the effect of the new medication not only elevated the mean function but shifted the range of function from 46%-72% personal best to 78%-102% personal best. At this new range of function the patient's system of care was not capable of delivering values that are at risk for severe asthma. Unless the range of function the change in care is capable of producing is specifically quantitated, misinterpretation of improvement data can occur. Developing the concept of the PEFR control chart involved examining and challenging traditional mental models for monitoring PEFR at home in the care of asthma, acquiring a better understanding of the workings of dynamic systems and with system thinking, and sharing what was learned with patients and seeking their input. The PEFR control chart employs an interesting statistical platform that enables the integration of knowledge of serial measurements and knowledge of the variation between those measurements into a tool with which to better assess the asthma care process being followed. This tool provides clinical insights, practical knowledge, and opportunities unavailable to patients and physicians via traditional PEFR charting.

Home Peak Expiratory Flow Rate Monitoring in Patients With Asthma

To describe how the peak expiratory flow rate (PEFR) is measured, review published studies of the accuracy in which patients and physicians can estimate the severity of asthma by clinical observations only, and review published studies of the benefits of home PEFR monitoring. A review of home PEFR monitoring and its associated benefits for both the physician and the patient is presented. An accurate assessment of the severity of asthma is crucial for the optimal treatment of the patient with asthma; however, patients and their physicians are often unable to estimate correctly the degree of airway obstruction. Peak flow measurement is a simple, inexpensive method of objectively determining airflow obstruction. Management of asthma based on home PEFR measurements can result in early recognition and prompt treatment of asthma exacerbations. Home PEFR monitoring in the setting of a comprehensive self-management program can lead to fewer symptoms of asthma, fewer days absent from work or school, fewer emergency examinations, fewer hospitalizations, lower requirements of inhaled beta-antagonists and oral corticosteroid therapy, and better pulmonary function. For best results, home PEFR monitoring should be coupled with a thorough educational program on asthma and periodic office spirometry.

Should we monitor peak expiratory flow rates or record symptoms with a simple diary in the management of asthma?

Background: Various means of monitoring asthma severity have been proposed to reduce morbidity and mortality rates. We compared two means of assessing asthma flare-ups: monitoring peak expiratory flow rate (PEFR) and keeping a symptom diary. Methods: This was a crossover randomized study. After a 2-week baseline period during which spirometry and PC 20 methacholine were assessed, subjects were asked to record either PEFRs or to keep a symptom diary morning and evening for 6 months; a second baseline assessment separated the two periods. Subjects were asked to contact the study coordinator if the following occurred: (1) in the period of PEFR monitoring, daily fluctuations in PEFR were >20% or the absolute value fell to <80% of baseline or both occurred; (2) in the period of symptom diary monitoring there were nocturnal symptoms or a persistence of morning dyspnea after inhaled bronchodilator or a reduction in the duration of effect of the bronchodilator or it was impossible to go to work or school or all occurred. In that case they were asked to come to the hospital to confirm the flare-up through investigation for significant changes in FEV, or PC 20 or both. Forty subjects completed a 6-month symptom diary or PEFR recording period respectively, and 20 completed both. Results: A total of 31 exacerbations were reported in 28 different subjects; three subjects had two flare-ups. Thirteen of 19 (69%) flare-ups were confirmed during the symptom diary period and 9 of 12 (75%) during PEFR monitoring. Nocturnal awakenings and morning falls in PEFR ≥20% were the most frequent occurrences. Conclusions: We conclude that a simple symptom diary may be as useful as serial PEFR monitoring in documenting asthmatic flare-ups.

Twice-daily peak expiratory flow rate monitoring for the assessment of childhood asthma.

The reliability of the home recording of peak expiratory flow rate (PEFR) in 31 newly diagnosed school-aged asthmatic children was monitored. The patients recorded their PEFR values in the morning and at bedtime and filled in their diary cards for 14 days. The mean amplitude of PEFR variation between the highest and lowest daily recordings varied from 1.9 to 34.4% (mean 6.7%) of the daily mean. Seven children, six of whom belonging to the most seriously affected half in the group had two or more daily PEFR variations of 15% or higher, but only two of them had their mean amplitude of variation at that limit or more. When the whole group was considered, however, no significant correlation was found between the mean amplitude of PEFR variation and the symptom score, the medication needed, baseline FEV1/FVC, or the methacholine threshold. The findings indicate that twice-daily PEFR monitoring may help the physician detect some troublesome cases of childhood asthma, but it is of limited value for diagnostic purposes or when assessing the degree of severity of asthma in routine clinical work.

Variability of peak expiratory flow rate as a prognostic index in asymptomatic asthma.

The prognostic relevance of an enhanced variability of peak expiratory flow rate (PEFR) throughout the day was evaluated in asthmatics in remission: it was expressed as the coefficient of variation (CV) of values recorded 4 times daily for 2 weeks. Outcome at 3, 6, and 12 months was assessed in 2 groups of 16 patients each, differing because of a CV respectively higher (group A) and lower (group B) than 8%. A significantly higher frequency of abnormal PEFR values during the subsequent 3 months was recorded in patients of group A, and found as correlated to the magnitude of CV; in the same group a significantly worse clinical status--scored on the basis of response to treatment--was pointed out. Therefore, a high CV of PEFR may be assumed as a reliable indicator of the risk of exacerbation--not otherwise predictable--both in a short and a longer term; on this basis home monitoring of PEFR may be recommended as a useful tool in the evaluation of all the cases of asthma in remission.