[Accuracy of MiniWright peak expiratory flow meters]

Peak expiratory flow in obese subjects in different positions

Objective: To analyze the peak expiratory flow (PEF) in obese subjects in standing (ST), seated (SE), supine (SU), prone (PR), and right and left lateral decubitus (RL and LL) positions. Methods: 36 obese volunteers, aged between 18 and 54 years, and nonsmokers, were evaluated by anthropometric data; spirometry; international physical activity questionnaire (IPAQ); and PEF in ST, SE, SU, PR, RL, and LL positions, randomly. Results: The mean age was 27.3 ± 7.4 years and BMI of 38.7 ± 3.2 kg/m²; IPAQ results: active (50%), irregularly active (25%), very active (16.7%), and sedentary (08.3%); spirometry results: FVC = 100.33%, FEV₁ = 92.83%, FEV₁/FVC ratio = 0.95, FEF_25-75% = 85.55%. The PEF (L/min) were within the normal range and there was no difference between the ST and SE (428.6 ± 100.9 and 430.0 ± 100.1). Comparing ST and SE to the other positions, in absolute and percent of predicted values (L/min and %), there was a decrease in the SU (85.4 ± 14.9), PR (401.1 ± 92.4 and 84.1 ± 14.4), RL (398.6 ± 94.7 and 83.3 ± 14.9) (p < 0.05), and there was no difference to SU (409.4 ± 102.8) and LL (410.3 ± 93.9 and 85.8 ± 14.5). Conclusion: The PEF of healthy obese are similar in the standing and seated positions. The PEF decreases in the lying positions, except for the LL, that could be used as an alternative for measurements.

Comparison of five portable peak flow meters

OBJECTIVE

To compare the measurements of spirometric peak expiratory flow (PEF) from five different PEF meters and to determine if their values are in agreement. Inaccurate equipment may result in incorrect diagnoses of asthma and inappropriate treatments.

METHODS

Sixty-eight healthy, sedentary and insufficiently active subjects, aged from 19 to 40 years, performed PEF measurements using Air Zone, Assess, Galemed, Personal Best and Vitalograph peak flow meters. The highest value recorded for each subject for each device was compared to the corresponding spirometric values using Friedman's test with Dunn's post-hoc (p<0.05), Spearman's correlation test and Bland-Altman's agreement test.

RESULTS

The median and interquartile ranges for the spirometric values and the Air Zone, Assess, Galemed, Personal Best and Vitalograph meters were 428 (263-688 L/min), 450 (350-800 L/min), 420 (310-720 L/min), 380 (300-735 L/min), 400 (310-685 L/min) and 415 (335-610 L/min), respectively. Significant differences were found when the spirometric values were compared to those recorded by the Air Zone(R) (p<0.001) and Galemed (p<0.01) meters. There was no agreement between the spirometric values and the five PEF meters.

CONCLUSIONS

The results suggest that the values recorded from Galemed meters may underestimate the actual value, which could lead to unnecessary interventions, and that Air Zone meters overestimate spirometric values, which could obfuscate the need for intervention. These findings must be taken into account when interpreting both devices' results in younger people. These differences should also be considered when directly comparing values from different types of PEF meters.

Comparison between PEF values obtained from a population sample in the city of São Carlos, Brazil, and reference values

OBJECTIVE

To compare the reference values for PEF suggested by other authors in 1963, 1989 and 2001 (for populations in the USA, England and Cuba, respectively) with those obtained from a population sample in the city of São Carlos, Brazil, and to determine whether there is concordance among them.

METHODS

A total of 243 volunteers (123 females and 120 males; 20-70 years of age) participated in the study. The PEF measurements were performed with the volunteer standing, using a nose clip, by means of a portable peak flow meter. These measurements were compared with the reference values using the Friedman test and Dunn's post-hoc test (p < 0.05).

RESULTS

Significant differences were found in all age groups from both genders regarding the values predicted in 1989; the same occurred in the 20-30 and 31-40 age groups (both genders), as well as in the 61-70 age group (females only), regarding those predicted in 2001, as well as in the 20-30 age group (males only) regarding those predicted in 1963.

CONCLUSIONS

The values predicted in 1963 are appropriate for a population of individuals with the same characteristics as the study sample, except for males in the 20-30 age group. Our study is relevant due to the fact that our sample was larger than that evaluated in the 1963 study. The majority of the values predicted in 1989 and 2001 overestimated the PFE values obtained in our study, proving to be inappropriate for the population studied.

Pulmonary function electronic monitoring devices: a randomized agreement study

STUDY OBJECTIVES

To compare in a clinical setting the within-session reproducibility of two pulmonary function electronic monitoring devices (PiKo-1; Ferraris Respiratory Europe; Hereford, UK; and Spirotel; MIR; Rome, Italy) with one mechanical device (Mini-Wright Peak-Flow Meter; Clement-Clarke International; Harlow, Essex, UK), and to evaluate the accuracy of these devices using as reference an office pneumotachograph.

DESIGN, SETTING, AND PARTICIPANTS

After detailed instructions, adults without airways diseases and patients with stable asthma attending an outpatient clinic performed four sets of expiratory maneuvers, one set for each device, in a strictly random order. Each set comprised three maneuvers with 2 to 3 min of rest between them.

MEASUREMENTS

Reproducibility of FEV1 and peak expiratory flow (PEF) was assessed by a coefficient of variation (CV) and intraclass correlation coefficient (ICC), and accuracy was assessed by ICC and limits of agreement.

RESULTS

Of the 38 participants evaluated, 71% were women and 61% had asthma. Ages ranged from 18 to 58 years, and FEV1 ranged from 1.2 to 4.8 L. In all monitoring devices, CV was < 6% and ICC was > 0.94 for the reproducibility of both FEV1 and PEF measurements. The accuracy of the PiKo-1 device was better for FEV1 (ICC = 0.98) than for PEF (ICC = 0.90). The Spirotel device had similar results for FEV1 and PEF (ICC = 0.95). The Mini-Wright device had the lowest accuracy (ICC = 0.87), particularly for PEF values < 500 L/min.

CONCLUSIONS

These low-cost and easy-to-use electronic monitoring devices showed a very good reproducibility and were in agreement with the pneumotachograph. Therefore, the PiKo-1 and Spirotel devices seem adequate for both screening and monitoring. However, prospective studies are still needed to assess their long-term reproducibility and usability and, particularly, the effects on the improvement of respiratory care.