Higher Peak Expiratory Flow Research Articles

Peak Flow Feedback Intervention Improves Under-Perception of Airflow Limitation in Pediatric Asthma: A Randomized Clinical Trial.

Under-perception of asthma symptoms is associated with poor asthma outcomes. We assessed the effects of a behavioral intervention for improving perception of airflow limitation and asthma outcomes. A two-arm randomized controlled trial compared peak expiratory flow (PEF) feedback versus supportive counseling. Latino and Black adolescents with asthma ages 10-17 years old and caregivers were recruited from hospitals in the Bronx, NY. PEF feedback sessions reviewed accuracy of PEF guesses and medication adherence data, and targeted behavior change using motivational interviewing and problem-solving skills training. Supportive counseling received emotional support related to asthma. Both groups received 3 sessions across 6 weeks. All participants were blinded to PEF while guessing PEF during pre-intervention, 1, 6, and 12-month follow-up. Children in PEF feedback saw actual PEF after guesses were locked in during the 6-week intervention. Participants and assessors were blinded to group assignment. The primary outcome was under-perception of airflow limitation (divergence between actual PEF and guesses) on home spirometers. Secondary outcomes included daily PEF and forced expiratory volume in 1 second (FEV1), inhaled corticosteroid adherence measured by electronic monitors, Asthma Control Test, and emergency healthcare use for asthma. The sample comprised 354 children (M = 13.2±2.2 years; 62% Latino, 38% Black) and caregivers. PEF feedback (N = 153 analyzed) demonstrated greater improvements at 1-month follow-up on under-perception of airflow limitation (difference-in-differences, -12.64; 95% CI, -17.54 to -7.74), % personal best PEF (9.89; 95% CI, 7.13 to 12.65), % predicted FEV1 (4.93; 95% CI, 0.95 to 8.90) and ICS adherence (16.02; 95% CI, 7.15 to 24.89) compared with supportive counseling (N = 152 analyzed). At 12-month follow-up PEF feedback maintained improvements on under-perception of airflow limitation (-13.87; 95% CI, -19.03 to -8.71), higher PEF (14.23; 95% CI, 11.37 to 17.08) and %FEV1 (5.62; 95% CI, 1.56 to 9.67), and had smaller declines in ICS adherence (17.51; 95% CI, 7.12 to 27.89) versus pre-intervention than supportive counseling. No between-group differences existed for asthma control or healthcare use. The efficacy and sustainability of PEF feedback was established in improving children's perception of airflow limitation, pulmonary function, and medication adherence. Clinical trial registration available at www. gov, ID: NCT02702687.

Association of peak expiratory flow with motoric cognitive risk syndrome among older adults.

The association between lung function and motoric cognitive risk syndrome (MCR) is unclear. We aimed to explore the association of peak expiratory flow (PEF) with MCR using cross-sectional and longitudinal analyses. Within the CHARLS, 5095 participants were included in the cross-sectional analysis, and 4340 MCR-free participants were included in the longitudinal analysis. The PEF was assessed with a lung peak flow meter. MCR was characterized by cognitive complaints and a slow walking speed with normal mobility and without dementia. Logistic regression, Cox regression, and Laplace regression models were employed for data analysis. In this cross-sectional study, logistic regression analyses revealed that continuous PEF was associated with MCR (odds ratio [OR], 0.998; 95% confidence interval [CI], 0.998, 0.999), and the ORs (95% CIs) of MCR prevalence were 0.857 (0.693, 1.061) for the middle tertile and 0.665 (0.524, 0.845) for the highest tertile compared to the lowest tertile. In a longitudinal cohort study, continuous PEF was dose-dependently associated with the risk of MCR. Compared with those in the lowest tertile of PEF, the hazard ratios (95% CIs) of incident MCR were 0.827 (0.661, 1,036) for the middle tertile and 0.576 (0.432, 0.767) for the highest tertile. Furthermore, compared with the lowest tertile, the highest tertile was associated with a delayed onset time of MCR of 0.484 (95% CI: 0.151, 0.817) years. A higher PEF was related to a lower prevalence of MCR and a lower risk for MCR, and a higher PEF also prolonged the onset time of MCR.

Impact of improved air quality on lung function and blood pressure of middle-aged and older population in China

Long-term exposure to fine particulate matters (PM2.5) has been associated with respiratory and cardiovascular diseases and the burden are potentially higher in China experiencing heavy air pollution. In this study, we established the exposure-response association between long-term exposures to PM2.5 and lung function and blood pressure in Chinese middle-aged and older adults using linear mixed-effects and generalized additive mixed models based on 3 waves longitudinal health outcomes data by enrolling 19,988 participants from 121 cities across the mainland of China. We also assessed the effect of Clean Air Policy (CAP) based on a quasi-experimental difference-in-differences (DID) design. A 10 µg/m3 increase in PM2.5 concentration was associated with a 7.18 (95 % confidence interval [CI]: -8.35, -6.02) L/min decrease in PEF (peak expiratory flow) and a 0.72 (95 % [CI]: 0.53, 0.90) and a 0.30 (95 % [CI]: 0.18, 0.42) mmHg increase in systolic and diastolic blood pressure, respectively. The associations were more pronounced in males and rural areas for PEF, but similar across subgroups for blood pressure. DID results suggested that the effect of CAP on health outcomes were sensitive to magnitudes of reduction in PM2.5. A 5 µg/m3 reduction in PM2.5 or more generally led to 18.70 (95 % [CI]:0.79, 36.61) higher PEF and -2.05 (95 % [CI]: -3.87, -0.23) lower diastolic blood pressure, respectively, compared to no reduction or increase in exposure. However, the effects were significant only in rural areas. Our analysis support CAP aiming to benefit public health and provides insights to inform future control policy for efficiently decreasing air pollution exposure burden.

Comparison of Mechanical Insufflation-Exsufflation and Hypertonic Saline and Hyaluronic Acid With Conventional Open Catheter Suctioning in Intubated Patients.

Open respiratory secretion suctioning with a catheter causes pain and tracheobronchial mucosal injury in intubated patients. The goal of mechanical insufflation-exsufflation (MI-E) is to move secretions proximally and noninvasively by generating a high peak expiratory air flow. Nebulized hypertonic saline with hyaluronic acid (HS-HA) may facilitate suctioning by hydration. We assessed the safety and tolerance of a single session of airway clearance with MI-E and HS-HA in critically ill intubated patients. Adults with a cuffed artificial airway were randomized to (1) open suctioning, (2) open suctioning after HS-HA, (3) MI-E, or (4) MI-E with HS-HA. Adverse events, pain and sedation/agitation scores, and respiratory and hemodynamic variables were collected before, during, and 5-min and 60-min post intervention. One-hundred twenty subjects were enrolled and completed the study. Median (interquartile range [IQR]) Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 22 (16-28); median (IQR) age was 69.0 (57.0-75.7) y, and 90 (75%) were male. Baseline respiratory and hemodynamic variables were comparable. Adverse events occurred in 30 subjects (25%), with no between-group differences. Behavioral pain equivalents and Richmond Agitation-Sedation Scale were higher during suctioning in groups 1 (P < .001) and 2 (P < .001). Independent predictive variables for higher pain and agitation/sedation scores were study groups 1 and 2 and simultaneous analgosedation, respectively. Noradrenaline infusion rates were lower at 60 min in groups 2 and 4. PaO2 /FIO2 had decreased at 5 min after open suctioning in group 1 and increased at 60 min in group 3. We observed no difference in adverse events. MI-E avoids pain and agitation.

Applicable predictive factors extracted from peak flow trajectory for the prediction of asthma exacerbation

BackgroundReal-time asthma exacerbation prediction and acute asthma attack detection are essential for patients with severe asthma. Peak expiratory flow (PEF) exhibits a potential for use in long-term asthma self-monitoring. However, the method for processing PEF calculations remains to be clarified. ObjectiveTo develop clinically applicable novel exacerbation predictors calculated using PEF records. MethodsPreviously proposed exacerbation predictors, including the slope of PEF, percentage predicted PEF, percentage best PEF, the highest PEF over the lowest PEF within specific periods, and PEF coefficient of variation, in addition to a novel indicator delta PEF moving average (ΔMA), defined as the difference between 14-day and 3-day average PEF values, along with moving average (MA) adjusted for PEF reference (%ΔMA), were verified using the Hokkaido-based Investigative Cohort Analysis for Refractory Asthma data of 127 patients with severe asthma from whom 73,503 PEF observations were obtained. Receiver operating characteristic curves for all predictors were drawn, and the corresponding areas under the curve (AUCs) were computed. Regression analysis for MA and percentage MA were conducted. ResultsThe most outstanding performance was shown by ΔMA and %ΔMA, with AUC values of 0.659 and 0.665 in the univariate model, respectively. When multivariate models were incorporated with random intercepts for individual participants, the AUC for ΔMA and %ΔMA increased to 0.907 and 0.919, respectively. ConclusionThe MA and percentage MA are valuable indicators that should be considered when deriving predictors from the PEF trajectory for monitoring exacerbations in patients with severe asthma. Trial RegistrationThe Hokkaido-based Investigative Cohort Analysis for Refractory Asthma was registered in the University Hospital Medical Information Network Clinical Trials Registry (UMIN ID: 000003254). https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000003917

ASSOCIATION BETWEEN PEAK EXPIRATORY FLOW AND INCIDENT HEART FAILURE AND MORTALITY IN MIDDLE-AGED AND OLDER CHINESE ADULTS

Objective: Previous studies have suggested that pulmonary dysfunction predicts incident cardiovascular disease, posing the question of whether peak expiratory flow, one of the most direct measurements of lung function, could present a modifiable risk factor. In the present study, we aimed to evaluate associations of peak expiratory flow with incident heart failure, cardiovascular death, and all-cause death. Design and method: This study included 93,161 participants from the China Patient-Centered Evaluative Assessment of Cardiac Events Million Persons Project in Southern China who had lung function measurements at baseline (year 2016-2017) and were annually followed-up to December 2020. The composite endpoints included hospitalization for heart failure, cardiovascular death, and all-cause death. Hospitalization for heart failure were ascertained by linking to the Inpatient Registry and confirmation of death was based on information from local government vital statistics offices. The relationship between peak expiratory flow and all outcomes was assessed using multivariable Cox regression adjusting for age, sex, education, annual income, insurance, residence, occupation, current smoking, current drinking, body mass index, hypertension, diabetes, coronary heart disease, and stroke at baseline. Results: The mean age was 54.2 years, and 60.7% were women. At 3.4 ± 0.9 years of follow-up, heart failure occurred in 1361 (1.5%), cardiovascular death in 365 (0.4%), all-cause death in 1346 (1.4%), and the composite in 2490 (2.7%). Compared with the lowest quartile, the HR (95% CI) of the highest quartile in peak expiratory flow was 0.66 (0.55 - 0.78) for incident heart failure, 0.70 (0.51 - 0.95) for cardiovascular death, 0.54 (0.46 - 0.64) for all-cause death, and 0.54 (0.47 - 0.61) for the composite. The restricted cubic spline showed significantly negative relationships of peak expiratory flow with all outcomes. In addition, the association between peak expiratory flow and incident heart failure was not significantly changed after mortality was treated as competing risks in the Fine–Gray proportional sub-distribution hazards models (HR [95% CI]: 0.87 [0.81 - 0.93]). Conclusions: Higher peak expiratory flow was significantly associated with decreased risks of incident heart failure, cardiovascular death, and all-cause death in middle aged and elderly Chinese adults, independent of and to a similar extent as major known cardiovascular risk factors.

Associations between pulmonary function and cognitive decline in the middle-aged and older adults: evidence from the China Health and Retirement Longitudinal Study.

Studies observing the relationship between pulmonary function and the risk of cognitive impairment in middle-aged and older adults was increasing, but the results were inconsistent. To date, evidence from longitudinal data is scarce and further research is urgently needed. We used data from the China Health and Retirement Longitudinal Study. Participants were enrolled in 2011/2013 and followed up in 2013, 2015 and 2018. Pulmonary function was assessed via peak expiratory flow (PEF). Cognitive function, measured by episodic memory and mental status, was assessed through a face-to-face interview in each survey. A total of 8,274 participants (52.86% males; mean age, 56.44 years) were included. The scores of global cognition (12.46 versus 11.51, P < 0.001) of men were significantly higher than women at baseline, with a total of 5096 participants (61.59%) declining during the follow-up. Higher baseline PEF was associated with lower absolute decline in global cognition (OR per 1-SD difference 0.921; P = 0.031) and mental status (OR per 1-SD difference 0.9889; P = 0.002) during follow-up in men, and significant associations between higher baseline PEF and a lower absolute decline in the episodic memory were both found in men (OR per 1-SD difference 0.907; P = 0.006) and women (OR per 1-SD difference 0.915; P = 0.022). Second analysis showed that the significant associations between positive PEF variation and a lower rate of 4-year decline in global cognition, mental status and episodic memory were all only found in men. In subgroup analyses, higher PEF at baseline was significantly associated with a lower absolute decline of global cognition among male individuals >60 years. Significant associations between higher PEF at baseline and lower absolute decline in global cognition and episodic memory during follow-up were only found in never-smokers, while higher PEF was related to lower absolute decline in mental status among non-smoking and smoking males. Pulmonary function correlates with cognitive functions in middle-aged and older people, especially males. Additional studies characterizing early and long-term PEF changes are needed.

Prognostic Value of Preoperative Peak Expiratory Flow to Predict Postoperative Pulmonary Complications in Surgical Lung Cancer Patients.

ObjectivesCough impairment may lead to excessive accumulation of pulmonary secretions and increase the risk of postoperative pulmonary complications (PPCs). Peak expiratory flow (PEF) is a sensitive indicator of cough ability. We aimed to investigate the correlation between PEF and PPCs for lung cancer patients undergoing lobectomy or segmental resection for improved risk assessment.MethodsThis retrospective study assessed 560 patients with non-small cell lung cancer admitted for surgery between January 2014 to June 2016. The measurements of PEF were performed before surgery and the clinical outcomes were recorded, including PPCs, postoperative hospital stay, hospitalization costs, and other variables.ResultsPreoperative PEF was significantly lower in PPCs group compared to non-PPCs group (294.2 ± 95.7 vs. 363.0 ± 105.6 L/min, P < 0.001). Multivariable regression analysis showed that high PEF (OR=0.991, 95%CI: 0.988-0.993, P < 0.001) was an independent protective factor for PPCs. According to the receiver operating characteristic (ROC) curve, a PEF value of 250 L/min was selected as the optimal cutoff value in female patients, and 320 L/min in male patients. Patients with PEF under cutoff value of either sex had higher PPCs rate and unfavorable clinical outcomes.ConclusionsPreoperative PEF was found to be a significant predictor of PPCs for surgical lung cancer patients. It may be beneficial to consider the cutoff value of PEF in perioperative risk assessment.

Military Service, Childhood Socio-Economic Status, and Late-Life Lung Function: Korean War Era Military Service Associated with Smaller Disparities.

Military service is associated with smoking initiation, but U.S. veterans are also eligible for special social, financial, and healthcare benefits, which are associated with smoking cessation. A key public health question is how these offsetting pathways affect health disparities; we assessed the net effects of military service on later life pulmonary function among Korean War era veterans by childhood socio-economic status (cSES). Data came from U.S.-born male Korean War era veteran (service: 1950-1954) and non-veteran participants in the observational U.S. Health and Retirement Study who were alive in 2010 (average age = 78). Veterans (N = 203) and non-veterans (N = 195) were exactly matched using coarsened exact matching on birth year, race, coarsened height, birthplace, childhood health, and parental and childhood smoking. Results were evaluated by cSES (defined as maternal education <8 yr/unknown or ≥8 yr), in predicting lung function, as assessed by peak expiratory flow (PEF), measured in 2008 or 2010. While there was little overall association between veterans and PEF [β = 12.8 L/min; 95% confidence interval (CI): (-12.1, 37.7); p = 0.314; average non-veteran PEF = 379 L/min], low-cSES veterans had higher PEF than similar non-veterans [β = 81.9 L/min; 95% CI: (25.2, 138.5); p = 0.005], resulting in smaller socio-economic disparities among veterans compared to non-veterans [difference in disparities: β = -85.0 L/min; 95% CI: (-147.9, -22.2); p = 0.008]. Korean War era military service appears to disproportionately benefit low-cSES veteran lung functioning, resulting in smaller socio-economic disparities among veterans compared with non-veterans.

Superoxide dismutase levels and peak expiratory flow in asthmatic children

involve variety of cells such as inflammatory mediators, reactive oxygen species (ROS), and cytokines. The inflammatory process would be exacerbated in the presence of oxidative stress. Superoxide dismutase (SOD) is the first important enzyme to protect the respiratory tract against oxidative stress. The decreased of SOD has a correlation with increased of airway obstruction and bronchospasm. Objective To assess for a correlation between superoxide dismutase (SOD) levels and peak expiratory flow, as well as to determine the impact of SOD levels for predicting asthma attacks. Methods We conducted a prospective cohort study at Dr. Sardjito Hospital, Yogyakarta, between February and April 2011 involving asthmatic children aged 5-18 years. Subjects’ serum SOD levels and peak expiratory flow were measured at the same time point. We then performed a prospective study following up on the same subjects to find out if they had a recurrent asthma attack within one month of the tests. We also reassessed their peak expiratory flow one month after blood specimens were obtained. Results Thirty-nine patients were enrolled in this study. There was no significant correlation between SOD level and peak expiratory flow [r=0.289; 95%CI -0.025 to 0.47; P=0.074]. However, older age was significantly associated with higher peak expiratory flow (􀁂=0.5; 95%CI 3.10 to 11.57; P=0.01). Lower levels of SOD increased the risk of asthma attacks in a month following the initial measurements (RR=5.5; 95%CI 1.6 to 18.9; P=0.009). Conclusion Superoxide dismutase (SOD) level is not significantly associated with peak expiratory flow. However, we find a relationship between older age and higher peak expiratory flow and a relationship between lower SOD levels and risk of asthma attacks within one month following the tests. [

Superoxide dismutase levels and peak expiratory flow in asthmatic children

involvevariety of cells such as inflammatory mediators, reactive oxygenspecies (ROS), and cytokines. The inflammatory process would beexacerbated in the presence of oxidative stress. Superoxide dismutase(SOD) is the first important enzyme to protect the respiratory tractagainst oxidative stress. The decreased of SOD has a correlation withincreased of airway obstruction and bronchospasm.Objective To assess for a correlation between superoxide dismutase(SOD) levels and peak expiratory flow, as well as to determinethe impact of SOD levels for predicting asthma attacks.Methods We conducted a prospective cohort study at Dr. SardjitoHospital, Yogyakarta, between February and April 2011 involvingasthmatic children aged 5-18 years. Subjects’ serum SOD levelsand peak expiratory flow were measured at the same time point.We then performed a prospective study following up on the samesubjects to find out if they had a recurrent asthma attack withinone month of the tests. We also reassessed their peak expiratoryflow one month after blood specimens were obtained.Results Thirty-nine patients were enrolled in this study. Therewas no significant correlation between SOD level and peakexpiratory flow [r=0.289; 95%CI -0.025 to 0.47; P=0.074].However, older age was significantly associated with higher peakexpiratory flow (􀁂=0.5; 95%CI 3.10 to 11.57; P=0.01). Lowerlevels of SOD increased the risk of asthma attacks in a monthfollowing the initial measurements (RR=5.5; 95%CI 1.6 to 18.9;P=0.009).Conclusion Superoxide dismutase (SOD) level is not significantlyassociated with peak expiratory flow. However, we find arelationship between older age and higher peak expiratory flowand a relationship between lower SOD levels and risk of asthmaattacks within one month following the tests. [

The association between ambient temperature and children's lung function in Baotou, China.

The objective of this study is to examine the association between ambient temperature and children's lung function in Baotou, China. We recruited 315 children (8-12 years) from Baotou, China in the spring of 2004, 2005, and 2006. They performed three successive forced expiratory measurements three times daily (morning, noon, and evening) for about 5 weeks. The highest peak expiratory flow (PEF) was recorded for each session. Daily data on ambient temperature, relative humidity, and air pollution were monitored during the same period. Mixed models with a distributed lag structure were used to examine the effects of temperature on lung function while adjusting for individual characteristics and environmental factors. Low temperatures were significantly associated with decreases in PEF. The effects lasted for lag 0-2 days. For all participants, the cumulative effect estimates (lag 0-2 days) were -1.44 (-1.93, -0.94) L/min, -1.39 (-1.92, -0.86) L/min, -1.40 (-1.97, -0.82) L/min, and -1.28 (-1.69, -0.88) L/min for morning, noon, evening, and daily mean PEF, respectively, associated with 1 °C decrease in daily mean temperature. Generally, the effects of temperature were slightly stronger in boys than in girls for noon, evening, and daily mean PEF, while the effects were stronger in girls for morning PEF. PM2.5 had joint effects with temperature on children's PEF. Higher PM2.5 increased the impacts of low temperature. Low ambient temperatures are associated with lower lung function in children in Baotou, China. Preventive health policies will be required for protecting children from the cold weather.

Physical Activity and Lung Function in Adolescents: The 1993 Pelotas (Brazil) Birth Cohort Study

PurposeTo evaluate the association between physical activity changes in those aged 11 to 15 years and lung function at age 15 years.MethodsThe original cohort comprised 5,249 hospital-born children during the calendar year of 1993 in Pelotas, Brazil. In 2004–2005 and 2008–2009, all cohort members were sought for follow-up visits. Self-reported physical activity was measured at ages 11 and 15 years. At the 2008–2009 visit, when participants were 15 years old, spirometry was performed. Linear regression was used, and all analyses were stratified by sex.ResultsOf the 5,249 original members of the cohort, 4,325 were located at 15 years of age, and spirometry was performed on 4,010 members. Forced expiratory volume in 1 second was not associated with physical activity. In girls, those who were active in leisure time in both periods have better percent-predicted forced vital capacity (β = 3.573 [95% confidence interval {CI}: 1.015, 6.130]) and forced expiratory volume in the 6 seconds (β = .095 [95% CI: .021, .168]) than those who were inactive in the two periods. Also in girls, those who became active at 15 years of age had higher peak expiratory flow than those who were inactive at 11 and 15 years of age. In boys, only those who became inactive in leisure time had worse peak expiratory flow (β = −.180 [95% CI: −.339, −.021]) than boys who were inactive at ages 11 and 15 years.ConclusionsSelf-reported leisure-time physical activity was associated with better effort-dependent lung function parameters, particularly among girls.

The effect of chronic carbon monoxide exposure on hs-CRP, CIM thickness and PEF in furnacemen

Objective: The relationship of atherosclerosis, carotid intima media thickness, high sensitive C-reactive protein and the airway narrowness in patients who were exposed to chronic carbon monoxide was evaluated. Materials and Methods: Forty seven healthy non-smoker male furnacemen who have been working at least ten years, and 48 non-smoker healthy men were enrolled to the study. The body mass index, blood pressure, total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, carotid intima media thickness, carboxyhemoglobin, high sensitive C-reactive protein and peak expiratory flow velocity of both groups were evaluated. Results: Carboxyhemoglobin (p <0.001), high sensitive C-reactive protein (p <0.001) and carotid intima media thickness (p <0.001) levels were found to be higher in furnaceman group. While the carotid intima media thickness (p <0.001), carboxyhemoglobin (p <0.001) and high sensitive C-reactive protein (p <0.001) values were observed significantly higher, the peak expiratory flow percentage was significantly lower in furnaceman group (p <0.001). There was a statistically significant correlation between age and carboxyhemoglobin (p <0.004); carboxyhemoglobin and high sensitive C-reactive protein levels (p <0.001); carboxyhemoglobin level and working years (p <0.001); high sensitive C-reactive protein values and working years (p <0.001); peak expiratory flow percentage and carboxyhemoglobin level (p <0.001), peak expiratory flow percentage and working years (p <0.001), peak expiratory flow percentage and age (p <0.007); high sensitive C-reactive protein levels and exposure year (p <0.001), carotid intima media thickness and exposure year (p = 0.035) in furnaceman group. Conclusion: Chronic carbon monoxide exposure increases high sensitive C-reactive protein and carotid intima media thickness in the course of time and lays the groundwork for atherosclerosis and also decre

Relationships of methacholine and AMP responsiveness with peak expiratory flow variability in children with asthma

Both bronchial responsiveness (BR) and peak expiratory flow (PEF) variability are increased in asthma. PEF variability is presumed to reflect the degree of BR in asthma. BR is commonly assessed by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare methacholine and adenosine 5'-monophosphate (AMP) responsiveness with regard to their relationships with PEF variability in children with asthma. Methacholine and AMP challenge tests were performed in 79 children with mild to moderate asthma, and a provocative concentration causing a 20% decline in forced expiratory volume in 1 s (PC(20)) was calculated for each challenge. Subjects recorded PEF each morning and each evening for 14 consecutive days. PEF variability was expressed as amplitude percentage mean (amp%mean; high PEF minus low PEF on each day, expressed as a percentage of their mean, averaged over 14 days), and as the lowest percentage highest (low%high; the lowest PEF expressed as a percentage of the highest PEF recorded over the period). Methacholine PC(20) correlated significantly but weakly with both indices of PEF variability (amp%mean: r=-0.285, P=0.011; low%high: r=0.238, P=0.034). However, there was a significant and strong correlation between AMP PC(20) and both amp%mean (r=-0.583, P=0.000) and low%high (r=0.496, P=0.000). For AMP PC(20), the correlations were stronger than for methacholine PC(20) (comparison of correlation coefficients with amp%mean: P=0.021; with low%high: P=0.063). Both methacholine PC(20) and AMP PC(20) correlated significantly with PEF variability. However, the stronger correlations for AMP PC(20) than for methacholine PC(20) suggest that PEF variability may be better reflected by BR assessed by AMP than by methacholine.

Correlates of Peak Expiratory Flow Lability in Elderly Persons

To determine the correlates of the lability of peak expiratory flow (PEF) in the elderly. A community sample of 4,581 persons > or = 65 years old from the Cardiovascular Health Study completed an asthma questionnaire and underwent spirometry. During a follow-up examination of the cohort, 1,836 persons agreed to measure PEF at home twice daily for 2 weeks, and 90% successfully obtained at least 4 days of valid measurements. PEF lability was calculated as the highest daily (PEF maximum - PEF minimum)/mean PEF. Mean PEF measured at home was accurate when compared to PEF determined by spirometry in the clinic. Mean PEF lability was 18% in those with current asthma (n = 165) vs 12% in healthy nonsmokers (upper limit of normal, 29%). Approximately 26% of those with asthma and 14% of the other participants had abnormally high PEF lability (> 29%). After excluding participants with asthma, other independent predictors of high PEF lability included black race, current and former smoking, airway obstruction on spirometry, daytime sleepiness, recent wheezing, chronic cough, emphysema, and wheezing from lying in a supine position. Despite having a lower mean PEF, those reporting congestive heart failure (n = 82) did not have significantly higher PEF lability. Measurement of PEF lability at home is highly successful in elderly persons. PEF lability > or = 30% is abnormal in the elderly and is associated with asthma.

Timing of lowest and highest peak expiratory flow in patients with asthma: influence of anti-inflammatory treatment

We sought to determine the optimal time for measuring peak expiratory flow rate (PEF) in patients with mild to moderate asthma, before and after treatment with inhaled beclomethasone dipropionate (BDP). After 2 weeks of observation, BDP (400 μ g/d) was given to 22 patients with mild to moderate asthma. The dose of BDP (800–1200μ g/d) was increased every 2 weeks until PEF varied by no more than 20% each day. PEF was measured four times daily: on awakening, around noon, in the evening and at bedtime. Significant (P<0·05) rhythms were detected by single cosinor analysis in all patients, both during observation and during treatment. Analysis by the population mean–cosinor method showed that the mean mesor was 378·8±59·1 l min−1, the mean amplitude was 53·9±13·4 l min−1, and the mean acrophase was at 16:26±0:32 before treatment. After treatment, the mean mesor was 528·0±61·9 l min−1, the mean amplitude was 37·6±12·2 l min−1, and the mean acrophase was at 16:35±0:32. The mesor increased significantly (P<0·05), and the amplitude decreased significantly (P<0·05) after treatment. The acrophase did not change. These data indicate that PEF is lowest at 04:30 and highest at 16:30 in patients with mild to moderate asthma, both during observation and during treatment. We conclude that if one needs to assess PEF twice a day, this should ideally be done at 04:30 and 16:30, not only before but also after treatment with BDP.

Gas compression artefacts when testing peak expiratory flow meters with mechanically-driven syringes

Mechanically-driven syringes used to test peak expiratory flow (PEF) meters must produce the American Thoracic Society (ATS) standard waveforms with PEF accuracy of 2%. However, gas compression within the syringe could result in significant PEF inaccuracy when testing high resistance meters. The gas compression artefact was investigated in a mechanical syringe (PWG; MH Custom Design & Mfg L.C., Midvale, Ut, USA) of 13.6 L connected to a standard range mini-Wright PEF meter (Clement Clarke International, Harlow, UK). Scaled versions of the ATS standard waveform No. 24, with peak flows of 750 and 450 L x min(-1), were discharged through the PEF meter from different starting piston positions to vary syringe volume (Vsyr). The PEF recorded by the meter decreased linearly with increasing Vsyr. PEF decreased by 0.31 and 0.27% per litre for the ATS standard waveforms with PEF of 750 and 450 L x min(-1), respectively. The target PEF computed from piston displacement overread the actual PEF delivered into the PEF meter by approximately 4% when Vsyr = 13.6 L. Overreading fell to approximately 1% when Vsyr was reduced to 3.62 L. Therefore, gas compression error in commercially available large mechanical syringes can exceed the 2% inaccuracy limit when testing high resistance portable PEF meters. Measurements can be corrected for gas compression by linearly extrapolating PEF recordings to zero volume.

Nocturnal Waking and Morning Dip of Peak Expiratory Flow in Clinically Stable Asthma Patients during Treatment

The occurrence of nocturnal waking due to asthma and morning dip of the peak expiratory flow (PEF), and the associated patient characteristics were investigated in 103 clinically stable asthmatic patients from a pulmonary outpatient clinic. Analysis of a 1 week diary showed a mean week morning PEF dip (i.e. morning/daytime highest PEF) of 12%. A mean dip of > or = 20% was found in 20% of the patients. Three groups were distinguished: 10% were 'nocturnal-waking patients' (waking up > or = 2 nights a week with a PEF dip of > or = 20%); 19% 'morning-dipping patients' (patients with > or = 3 dips a week of > or = 20% but with waking up on < 2 nights a week) leaving 71% 'remaining patients'. 28% of all patients showed morning PEF dips. In a questionnaire, waking every night was reported by 9%, at least once a week by 42% and once a month by 72%. In 'nocturnal-waking patients' FEV1 and morning and evening PEFs were lower than in 'remaining patients'; complaints during the night and on rising were more severe. The morning PEF dip was the same in 'nocturnal-waking patients' and 'morning-dipping patients'. The occurrence of waking was the same in 'morning-dipping patients' and in the 'remaining patients'. There were no differences in other clinical parameters among the three groups. We conclude that a subset of clinically stable asthma patients presents morning dips and nocturnal waking. They do not differ substantially from the remaining patients in other clinical characteristics.

Seasonal variations in house dust mite influence the circadian peak expiratory flow amplitude.

The aim of the study was to investigate whether seasonal differences in house dust mite (HDM) allergen exposure influence the circadian peak expiratory flow (PEF) amplitude in asthmatic children. Asthmatic children (n = 25) with a solitary allergy to HDM were studied in spring and in autumn. All used inhaled corticosteroids (ICS) regularly. Six days after withdrawal of ICS, PEF amplitude (every 4 h during 24 h, highest-lowest/percentage of mean value) was assessed. HDM allergen (HDMA) in living rooms, bedrooms, and mattresses was collected. HDMA levels were not always highest in autumn. PEF amplitudes in spring and autumn did not correlate with HDMA levels in the same season. However, the seasonal difference in PEF amplitude (autumn value - spring value) correlated positively and significantly with the seasonal difference in HDMA exposure levels from the mattresses (rho = 0.34, p < 0.05). Multivariate analysis showed that the seasonal difference in HDMA exposure in the mattress was the single parameter explaining seasonal difference in PEF amplitudes by 21.0% (p = 0.02). Our cross-sectional study showed a higher PEF amplitude not to be significantly associated with higher HDMA exposure in mattresses in a group of HDM-allergic asthmatic children. However, the change in HDMA exposure over seasons contributed significantly to the change in PEF amplitude after withdrawal of ICS in HDM-allergic asthmatic children.