Measurement of Forced Expiratory Flows and Lung Volumes (original) (raw)
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Forced expiratory flows and lung volumes in normal infants
Pediatric Pulmonology, 1993
Forced expiratory flows at functional residual capacity (VmaxFRC) by the rapid compression technique and functional residual capacity (FRC) by the helium dilution technique were assessed in 112 normal infants with a mean age of 10.7 months (range, 1.0–31.0). In predicting FRC, log transformation was appropriate and body length was the best predicator. For VmaxFRC, age was a better predictor than length, and logarithmic transformation was not required. There were no gender differences for FRC or VmaxFRC; however, male infants exposed to passive cigarette smoke tended to have lower flows than male infants not exposed (P < 0.07). This study establishes normative values for VmaxFRC and FRC in infants between 1 and 31 months of age, and suggests that passive cigarette smoke exposure has an adverse effect upon forced expiratory flows in male infants. © 1993 Wiley-Liss, Inc.
Reproducibility of forced expiratory flow and volume measurements in infants with bronchiolitis
Pediatric Pulmonology, 1999
The end-tidal rapid thoracoabdominal compression (ETRTC) technique is an established method for lung function testing in infancy. Previous work in healthy infants, however, has shown that measurements with the newly developed raised volume rapid thoracoabdominal compression (RVRTC) technique are more reproducible than those with the ETRTC technique. So far, reproducibility of the two techniques has not been compared in infants with acute airway disease. Twenty-three infants with acute viral bronchiolitis underwent lung function assessment with both the ETRTC and the RVRTC technique. A series of 8-10 measurements with each technique was done in randomized order. Forced expired volumes at 0.5, 0.75, and 1 sec after chest compression (FEV 0.5 , FEV 0.75 , and FEV 1.0) were measured with the RVRTC technique; maximum expiratory flow at functional residual capacity (VЈ maxFRC) was measured with the ETRTC technique. Group mean intrasubject coefficients of variation (CV) were 4.84% for FEV 0.5 , 5.01% for FEV 0.75 , 5.43% for FEV 1.0 , and 13.79% for VЈ maxFRC , respectively. Differences between FEV parameters were statistically insignificant, whereas the difference between each FEV parameter and VЈ maxFRC was highly significant (P < 0.001). In infants with acute viral bronchiolitis, RVRTC measurements have significantly less intraindividual variability than flow rates assessed with the conventional ETRTC technique. This finding provides the basis for assessing disease course and effects of therapeutic interventions on an individual basis.
Relation between partial and raised volume forced expiratory flows in sick infants
Pediatric Pulmonology, 2010
Rationale: The maximal expiratory flow-volume (MEFV) and the partial expiratory flow-volume (PEFV) maneuvers are interchangeably performed when testing infant lung function. In recent years, the MEFV has gained popularity over the PEFV as it offers the investigator various forced expiratory flow and volume variables in addition to the sole, maximal flow at functional residual capacity ( _ VmaxFRC) available from the PEFV maneuver. Both types of measure are considered to provide information on airway function. Objectives: To compare _ VmaxFRC values by PEFV to flows at low lung volumes by MEFV in infants suffering from a variety of illnesses. Methods: Retrospective analysis of records of 175 infants attending a tertiary out-patient clinic (age range 2-234 weeks). Comparisons between parameters derived from the PEFV and MEFV curves were made by linear regression and by Bland-Altman plots. Measurements and Main Results: _ VmaxFRC highly correlated with forced expiratory flows at 85% of forced vital capacity (FEF 85 ; r ¼ 0.87, P < 0.0001) with a mean bias of 20 ml/sec, and at 75% (FEF 75 ; r ¼ 0.83, P < 0.0001) with a greater mean bias of À72 ml/sec, but less with forced expired volume in 0.5 sec (FEV 0.5 ; r ¼ 0.66, P < 0.0001) showing a much wider scatter especially in infants with more severe obstruction. Same agreement between _ VmaxFRC and FEF 85 or FEF 75 was seen when presented as z-scores (r ¼ 0.77 and 0.76; respectively). Conclusions: Regardless of the maneuver performed, PEFV or MEFV, _ VmaxFRC and FEF 85 , and FEF 75 show high agreement in sick infants. As they both describe small airways function, both maneuvers may be interchangeable.
Referencing lung volume for measurements of respiratory system compliance in infants
Pediatric Pulmonology, 1993
We propose a method for measurements of respiratory system compliance ( C , ) in spontaneously breathing infants, which circumvents the potential problems introduced by the breathby-breath oscillations in the end-expiratory level, i.e., functional respiratory capacity (FRC). Changes in lung volume (V) and pressure at the airway opening (P, ) were measured in 10 infants breathing through a face mask. A first brief occlusion was to establish a reference V and the corresponding static Pao; a second occlusion was done at a different V. within the same expiration, or in the following breath. Both occlusions were sufficiently long for the establishment of a stable P, value. From the V difference (6V, where 6V was at least 20% tidal volume) and the corresponding difference in Pa, (tipm) C , was computed and averaged (C,[REF.
Raised-Volume Forced Expiratory Flow-Volume Curve in Healthy Taiwanese Infants
Scientific Reports, 2017
The raised-volume rapid thoracoabdominal compression (RVRTC) manoeuvre has been applied to obtain full forced expiratory flow-volume curves in infants. No reference data are available for Asian populations. This study was conducted to establish predictive reference equations for Taiwanese infants. Full-term infants without any chronic disease or major anomaly were enrolled from this cohort study. Full forced expiratory flow-volume curves were acquired using RVRTC manoeuvres through Jaeger's system. Tidal breath analysis, passive respiratory mechanics, and tidal forced expiratory flow-volume curves were performed and collected at the same measurement. Multiple linear analyses were used to model the variables. We performed 117 tests of RVRTC flow-volume curves in 97 infants. The results revealed that all parameters, except for FEV 0.5 /FVC, correlated highly and positively with body length. These parameters correlated significantly with other parameters of passive respiratory mechanics and tidal forced expiratory flow-volume curves. This is the first study to establish equipmentspecific reference data of full forced expiration using RVRTC manoeuvres in Asian infants. The results revealed that parameters of RVRTC manoeuvres are moderately related to other parameters of infant lung function. These race-specific reference data can be used to more precisely and efficiently diagnose respiratory diseases in infants of Chinese ethnicity. Many chronic paediatric respiratory diseases, such as bronchopulmonary dysplasia, asthma, and cystic fibrosis, originate early in life. However, techniques available for investigating the respiratory function of young children, particularly infants, are limited. Infant lung function (ILF) testing has been shown to be useful for the early diagnosis of and efficient intervention in lung diseases 1-4. In the past, a partial expiratory flow-volume curve obtained using the rapid thoracoabdominal compression (RTC) manoeuvre has been used to assess airway function 5-7. However, because this curve is collected only in the range of tidal volume, flow limitation is occasionally difficult to achieve in healthy infants 8, 9. In addition, the maximal expiratory flow measured in functional residual capacity (Vmax FRC) is relatively unstable because the end-expiratory level may be dynamically high in young infants. Recently, the raised-volume RTC (RVRTC) technique, initiated near total lung capacity, has been utilised to obtain a full forced expiratory flow-volume curve. This manoeuvre has been shown to differentiate between healthy infants and those with respiratory diseases 5, 10, 11. During the past 10 years, increasing RVRTC reference data from healthy infants have been reported 8, 12. The American Thoracic Society/European Respiratory Society (ATS/ERS) task force has developed clinical practice guidelines for the RVRTC technique 5, 11, 13. However, all the data have been obtained for Caucasian populations and thus studies on individuals of Asian ethnicity are lacking. The present study was therefore conducted to establish prediction equations for RVRTC data in Taiwanese children during the first 2 years of life. Moreover, after considering sex, age, body weight, and body height, we developed equations that can be expressed as Z-scores. In addition, we investigated the correlation between RVRTC data and other ILF parameters that have been widely used in the past. Results We performed 117 tests in 97 infants (56 boys). Of these, 20 infants received repeated tests at least 5 months apart. The median age, body length, and body weight of the infants were 8 (range, 5-26) months, 78 (range, 63-91) cm,
Archivos De Bronconeumologia, 2007
Forced expiratory maneuvers from an increased lung volume in infants date from 1989 and consist of raising the inspiratory volume by applying a specific inflation pressure until a level close to the total lung capacity is reached. The chest and abdomen are then compressed by means of an inflatable jacket in order to obtain a forced expiratory flow-volume curve similar to that obtained for an adult. Forced expiration from an increased lung volume in infants is useful, just as the maneuver is in older patients, for studying airway function, diagnosing obstructive diseases early, and assessing response to treatment.
A radiographic method for estimating lung volumes in sick infants
Pediatric Pulmonology, 1992
Estimation of lung volumes by conventional methods in sick infants is technically difficult and is the subject of controversy. In this study, we compared both thoracic gas volume (TGV). measured with an infant whole body plethysmograph, and functional residual capacity (FRC), determined by the nitrogen washout technique, to planimetric measurements of anteroposterior chest radiographs in 26 infants with bronchopulmonary dysplasia (BPD).
Pediatric Research, 1991
We assessed pulmonary function in 14 mechanically ventilated newborn very low birth weight infants with idiopathic respiratory distress syndrome by means of a face-out, volume displacement body plethysmograph and nitrogen washout analyses. Specially designed computer programs were used for calculations of lung volumes, ventilation, gas mixing efficiency, and mechanical parameters. In addition to very low compliance and moderately elevated resistance of the respiratory system, there were considerably impaired gas mixing efficiency and low functional residual capacity (FRC). No correlations between positive end-expiratory pressure and mean airway pressure versrrs compliance, resistance, or FRC could be found. Neither could correlations be found between FRC and compliance or FRC and the calculated right to left shunt. (Pediatr Res 30: 496-500,1991) Abbreviations Fi02, fraction of inspired oxygen FRC, functional residual capacity IRDS, idiopathic respiratory distress syndrome MAP, mean airway pressure NC, nitrogen clearance Pao*, arterial oxygen tension PIP, peak inspiratory pressure For methodologic reasons, lung function studies in newborn infants with IRDS have largely been focused on lung mechanics. Using applied methods makes it possible to obtain a more comprehensive picture of ventilatory conditions, even in very premature, severely affected infants. To further clarify the pathophysiology of IRDS under conditions of mechanical ventilation in this group of infants, we assessed lung volume, alveolar ventilation, gas mixing efficiency, and lung mechanics in mechanically ventilated infants with birth weights below 1500 g. MATERIALS AND METHODS We studied 14 very low birth weight infants with IRDS during intermittent positive pressure ventilation within 5 d (range 0-5 d) of birth. Six of the infants were boys and eight were girls. Median birth weight was 1.29 kg (range 1.00-1.50 kg) and
Archives of disease in childhood. Fetal and neonatal edition, 2018
To assess the work of breathing at different levels of volume targeting in prematurely born infants with evolving or established bronchopulmonary dysplasia (BPD). Randomised crossover study. Tertiary neonatal intensive care unit. Eighteen infants born at <32 weeks gestation who remained ventilated at or beyond 1 week after birth, that is, they had evolving or established BPD. Infants received ventilation at volume targeting levels of 4, 5, 6 and 7 mL/kg each for 20 minutes, the levels were delivered in random order. Baseline ventilation (without volume targeting) was delivered for 20 minutes between each epoch of volume-targeting. Pressure-time product of the diaphragm (PTPdi), a measure of the work of breathing, at different levels of volume targeting. The 18 infants had a median gestational age of 26 (range 24-30) weeks and were studied at a median of 18 (range 7-60) days. The mean PTPdi was higher at 4 mL/kg than at baseline, 5 mL/kg, 6 mL/kg and 7 mL/kg (all P≤0.001). The mea...
Archives of Disease in Childhood - Fetal and Neonatal Edition, 2006
Background: An objective definition of bronchopulmonary dysplasia (BPD) is required to interpret trial outcomes and provide a baseline for prognostic studies. Current definitions do not quantify disease severity. The cardinal measures of impaired gas exchange are a reduced ventilation:perfusion ratio (V A :Q) and increased right to left shunt. These can be determined non-invasively by plotting arterial oxygen saturation (SpO 2 ) against inspired oxygen pressure (PIO 2 ). Aims: To describe the reduced V A :Q and shunt in infants with BPD and evaluate these as graded measures of pulmonary dysfunction. Methods: 21 preterm infants with BPD were studied. PIO 2 was changed stepwise to vary SpO 2 between 86% and 94%. Pairs of PIO 2 and SpO 2 data points for each infant were plotted and analysed to derive reduced V A :Q ratio and shunt. Results: In every infant, the SpO 2 versus PIO 2 curve was shifted to the right of the normal because of a reduced V A :Q. The mean (SD) shift was 16.5 (4.7) kPa (normal 6 kPa). Varying degrees of shunt were also present, but these were less important in determining SpO 2 within the studied range. The degree of shift was strongly predictive of the PIO 2 required to achieve any SpO 2 within the range 86-94% (R 2 .0.9), permitting shift and V A :Q to be determined from a single pair of PIO 2 and SpO 2 values in this range. Conclusions: The predominant gas exchange impairment in BPD is a reduced V A :Q, described by the right shift of the SpO 2 versus PIO 2 relationship. This provides a simpler method for defining BPD, which can grade disease severity.