Incorrect use of peak flow meters: are you observing your patients?
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Abstract:
Monitoring peak expiratory flow (PEF) values is one option as part of asthma action plans per national guidelines. PEF assessment is also recommended in emergency department and hospitalized patients. Incorrect use of peak flow meters (PFM) has obvious implications for appropriate decisions by patients and clinicians.We searched the English literature via PubMed and SCOPUS using the following search terms: PEF maneuver; incorrect use of PFM. When pertinent articles were found, we assessed publications cited in those papers. All studies related to incorrect use of PFM in patients with asthma were included.Nine studies have reported errors in performing the PEF maneuver, including three pediatric and six adult studies. Errors were found at most steps of the maneuver, and inability to perform all steps correctly was common in these investigations. Examples of errors included failure to inhale fully or give maximum effort on exhalation, accelerating air with the tongue and buccal musculature, and performing only one attempt versus three. Gender differences in correct use of PFM are suggested by three adult studies. One study described falsifying PEF values by manipulating the PFM indicator, and another investigation assessed the PEF maneuver in two positions in bed versus the correct posture of standing.Many pediatric and adult patients do not use PFM correctly. Clinicians should regularly observe patients use PFM to detect errors and help ensure correct use and accurate PEF measurements.Keywords:
Exhalation
Peak flow meter
Background: The understanding of the real flow profiles through a dry powder inhaler (DPI), generated by asthma patients, is a prerequisite for satisfactory drug delivery to the lungs. The aims of the study were to assess the relationship between spirometric measures and inhalation profiles through a low-resistance DPI, and to compare parameters of those profiles between optimal and suboptimal inhalation technique type. Methods: Both healthy adult volunteers and patients with asthma were included in the study. Spirometry was conducted along with modified flow-volume test to detect expiratory levels (maximum “100%” exhalation to residual volume [RV] and halfway “50%” to RV). These were the reference levels of the depth of exhalation for each patient to simulate the effect of incomplete exhalation. Individual inhalation profiles were recorded using spirometry in-house software as the volumetric airflow through the inhaler versus time. Inspiratory flow parameters were extracted: time to peak inspiratory flow through inhaler (PIFinh), time at which peak inspiratory flow occurs (tPIFinh), total inhalation time (T), and inhaled volume during maneuver (V). Results and Conclusions: There are significant relationships between spirometric indices and parameters of inhalation through a low-resistance, cyclohaler-type DPI (assessed by single-factor analysis of Spearman's rank correlation coefficient). Multiple regression models were constructed, predicting inspiratory flow parameters (including spirometric indices, demographic parameters, and inhaler's usage history as determinants). The exhalation halfway to RV before inhalation did not affect significantly PIFinh and tPIFinh (and, thus, initial flow dynamics) in asthma patients. T and V parameters were then significantly decreased, but seemed sufficient for successful DPI performance. Both exhalation to RV and incomplete exhalation halfway to RV preceding inhalation allow for effective usage of low-resistance DPI.
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Peak flow meter
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Ventilator exhalation-valve performance during the expiratory phase has been studied in depth. An active exhalation valve uses servo-control technology that allows gas to be released from the exhalation valve during the inspiratory phase if the patient makes an expiratory effort. We conducted a bench study of active exhalation valve response to expiratory effort during the inspiratory phase.We studied 4 ventilators that have active exhalation valves (Maquet Servo-i, Newport e500, Puritan Bennett 840, and Evita XL) and one that does not (Puritan Bennett 7200ae). With an active test lung we simulated various magnitudes of expiratory effort during the middle of the inspiratory phase. We measured the exhalation resistance and pressure over-shoot during the expiratory effort, and we measured the pressure under-shoot after the expiratory effort. The exhalation resistance of the 7200ae could not be determined because this ventilator did not allow any gas-release through the exhalation valve during the expiratory effort.The exhalation resistance of the Evita XL (6.6 +/- 1.8 cm H(2)O/L/s) was higher than that of the Servo-i (3.0 +/- 1.3 cm H(2)O/L/s), e500 (2.6 +/- 0.8 cm H(2)O/L/s), and 840 (3.5 +/- 0.8 cm H(2)O/L/s) (all P < .001). The magnitude of pressure over-shoot during the expiratory efforts was not significantly different among the 4 ventilators with active exhalation valves. Pressure over-shoot was significantly higher with the 7200ae than with any of other ventilators (all P < .001).There was a significant difference in exhalation resistance between the Evita XL and the other 3 ventilators with active exhalation valves. All 4 ventilators with active exhalation valves had lower exhalation resistance than the 7200ae.
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ABSTRACT: School‐based health centers (SBHCs) are increasingly charged with providing primary care services including asthma care. This study assessed SBHC provider adherence to the National Heart, Lung, and Blood Institute (NHLBI) asthma care guidelines and the association among provider adherence, patient characteristics, and asthma outcomes. A cross‐sectional study design was used to assess SBHC chart data from 415 children with asthma attending four inner‐city elementary schools (K‐5) in the Bronx, NY. Asthma symptoms, peak flow use, follow‐up visits, and referrals to asthma specialists were documented in the charts of 60%, 51%, 22%, and 3% of subjects, respectively. Thirty‐three percent of charts had SBHC clinician‐documented severity classifications, of which 70% had appropriate medications prescribed. Asthma education and an asthma plan were documented in 18% and 10% of charts, respectively. Environmental triggers and tobacco exposures were documented in 71% and 49% of charts, respectively. Older children (> 8 years) were more likely to have documentation of peak flow use for asthma management, asthma education, follow‐up visits, and written asthma plans, whereas younger children (< 8 years) were more likely to miss more days of school (all p < .05). Overall, provider adherence to NHLBI guidelines was inadequate, with adherence somewhat better for older children.
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Patient Education
Cross-sectional study
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We administered a 65-item survey to patients to assess preference of symptoms and peak flow to detect worsening asthma and to collect information about asthma triggers, asthma knowledge sources, and barriers to peak flow meter use. It was completed by 139 asthma patients. Survey responses were comparable for adult and pediatric patients and for those who owned peak flow meters and those who did not. But patients who owned a peak flow meter reported more severe asthma than others. On average, the patients preferred symptoms to peak flow for assessing worsening asthma. It is likely that the preference for symptom over peak flow monitoring was effort related: Patients preferred symptom monitoring because it was the easier of the two to conduct.
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Background: The severity of airway obstruction may affect patient's ability to perform an effective drug inhalation from a dry powder inhaler (DPI). Also, an incorrect inhalation technique may negatively affect the efficacy of asthma treatment. The aims of the study were (1) to analyze and compare inhalation profiles recorded with the use of different inhalation techniques, and thus, (2) to establish model inhalation profiles representative for healthy subjects and subjects with mild and moderate-to-severe asthma. Methods: This study was performed in healthy volunteers, patients with mild and moderate-to-severe asthma. A modified flow-volume test to define two different expiratory levels (to residual volume and half-way to residual volume) was performed. Inspiratory flow parameters were extracted: peak inspiratory flow rate (PIFinh), time at which peak inspiratory flow rate occurs (tPIFinh), total inhalation time (T), and inhaled volume (V). Test of frequency for tPIFinh100% and tPIFinh50% by asthma severity was performed, to provide information about initial flow accelerations. The impact of two different expiratory levels preceding inhalation (with severity of asthma as a categorical factor) on inspiratory flow parameters was examined. Results: PIFinh was dependent upon asthma severity (p = 0.046). Type of exhalation before inhalation had no effect on PIFinh values. V value was significantly affected both by asthma severity (p = 0.024) and type of exhalation before inhalation (p < 0.0001). Mean T value was influenced by type of exhalation before inhalation (p = 0.0003), but not by asthma severity. Mean tPIFinh value was affected by the type of exhalation before inhalation only in healthy subjects (p = 0.01). Conclusions: Both asthma severity and type of exhalation before inhalation have little impact on the dynamics of inhalation through a DPI. An alternative form of equation describing inhalation profiles demonstrating a relationship between lung mechanics and dynamics of inspiratory profile has been proposed.
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Although exhalation immediately prior to inhalation (EPI) from dry powder inhalers (DPIs) is universally advised, its benefit has not been investigated. The objective of this study to assess the effects of EPI on inhaled flow from a DPI.We measured peak inhaled flow rate (PIFR) and inhaled gas volume of 25 volunteers unfamiliar with DPIs. They inhaled strongly and deeply through a flow meter either with or without EPI before and after connecting Turbuhaler or Diskus.Median PIFR increased significantly with EPI both without connection to DPIs (178.8 versus 140.4 L min(-1)), and with connection to Diskus (75.6 versus 67.8 L min(-1)), or to Turbuhaler (51.0 versus 48.0 L min(-1)). As a result, the number of subjects whose PIFR exceeded 60 L min(-1) was significantly increased with connection to either Diskus (76 versus 64%) or to Turbuhaler (24 versus 4%). EPI significantly increased median inhaled volume both without connection to DPIs (2.84 versus 1.84 L), and with connection to Diskus (1.95 versus 1.66 L), or to Turbuhaler (1.86 versus 1.28 L). EPI significantly increased F0.2 (flow at 0.2 s after onset of inhalation) and AC30 (flow acceleration at 30 L min(-1)), parameters representing the rate of flow increase during the early phase of inhalation, in all the three groups.EPI increases PIFR which may augment drug dispersion and facilitate fine particle generation from a DPI.
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Patient self-management, besides expert care, is necessary to improve health outcomes among persons with asthma. Our objective was to describe the characteristics of persons with asthma likely to receive asthma self-management education.The 2006 and 2007 Behavioral Risk Factor Surveillance System (BRFSS) Child and Adult Asthma Call-back Survey (ACBS) data were analyzed. Binary and multinomial response logistic regression models were used to examine the association between asthma self-management education and explanatory variables.Of the 31,278 persons who ever had asthma, 3953 of the children (75.8%) and 19,723 of the adults (72.8%) were classified as having active asthma. For both children and adults, the three most commonly reported asthma education components were being taught how to use an inhaler (78.6% and 89.8%, respectively); being taught what to do during an asthma episode (86.3% and 74.6%); and to recognize early signs or symptoms of an asthma episode (82.0% and 64.4%). Children and adults who reported routine care visits, hospitalization, and asthma episodes in the past 12 months because of asthma were more likely to report several asthma education components and higher asthma education scores. Children aged 12-17 years were more likely to report having instruction in peak flow meter use (1.3; 1.1-1.6) and inhaler use (1.3; 1.2-1.4), whereas older adults (aged 54-64 years or 65+ years), adults who were not high school (HS) graduates, and smokers were less likely to report having asthma management education than the corresponding comparison groups.Having a routine care visit, being hospitalized, and having an asthma episode were significantly associated with reporting multiple asthma education components, whereas being an older adult, having less than a HS degree, and being a smoker were associated with reporting fewer asthma education components. Asthma control programs should continue to monitor asthma self-management education and promote asthma education to all persons with asthma, especially for older adults, persons with less education, and smokers.
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Dry powder inhalers (DPIs) are breath actuated, and patients using DPIs need to generate an optimal inspiratory flow during the inhalation maneuver for effective drug delivery to the lungs. However, practical and standardized recommendations for measuring peak inspiratory flow (PIF)-a potential indicator for effective DPI use in chronic obstructive pulmonary disease (COPD)-are lacking. To evaluate recommended PIF assessment approaches, we reviewed the Instructions for Use of the In-Check™ DIAL and the prescribing information for eight DPIs approved for use in the treatment of COPD in the United States. To evaluate applied PIF assessment approaches, we conducted a PubMed search from inception to August 31, 2021, for reports of clinical and real-life studies where PIF was measured using the In-Check™ DIAL or through a DPI in patients with COPD. Evaluation of collective sources, including 47 applicable studies, showed that instructions related to the positioning of the patient with their DPI, instructions for exhalation before the inhalation maneuver, the inhalation maneuver itself, and post-inhalation breath-hold times varied, and in many instances, appeared vague and/or incomplete. We observed considerable variation in how PIF was measured in clinical and real-life studies, underscoring the need for a standardized method of PIF measurement. Standardization of technique will facilitate comparisons among studies. Based on these findings and our clinical and research experience, we propose specific recommendations for PIF measurement to standardize the process and better ensure accurate and reliable PIF values in clinical trials and in daily clinical practice.
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The aim of the study was to determine whether asthma management in Thailand is succeeding in achieving the levels of control, specified in national and international asthma guidelines.Adults with asthma in Bangkok, Chiang Mai, Songkhla, and Khon Kaen were interviewed, and we have reported on their asthma severity, morbidity, control, perception of asthma, and healthcare use.A total of 466 asthma sufferers were interviewed. The burden of asthma was high, with 14.8% of respondents being hospitalized for their asthma in the past year. One-quarter of those surveyed had lost workdays as a result of their asthma, and most patients felt that their lifestyle was limited. The majority of respondents had intermittent asthma (62.9%), 10.5% had mild persistent asthma, 17.6% had moderate persistent asthma, and 9.0% had severe persistent asthma; increasing severity was significantly associated with increased emergency healthcare use (P < 0.00001). Asthma sufferers greatly underestimated the severity of their condition. Only 36.0% used reliever medication, and use of inhaled corticosteroids was low at 6.7%. Understanding of the inflammatory basis of asthma was poor. Few patients underwent lung function tests or took peak flow meter readings.The burden of asthma is high in Thailand, and guidelines are not being followed. Encouraging greater use of inhaled corticosteroids will be an important step towards improving asthma control.
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