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PubMed1997

[Forced expiration. Various current concepts, 50 years after Robert Tiffeneau].

One hundred and fifty years after the original description of spirometry by Hutchinson and 50 years after the definition of his famous ratio by Tiffeneau, a certain number of physiological advances have enabled a better understanding of the determinants of the forced expired manoeuvre and to mitigate some of its inconveniences. This review focuses on three of these advances. The first is the influence of an inspiratory manoeuvre which precedes a forced expiration, on the expiratory flow. This influence is probably a consequence of viscoelastic phenomena and impose some strains on standardisation in current practice. The second is the possibility of detecting in a reproducible and simple fashion, without the need for co-operation on the part of the subject, a limitation in expiratory flow by the application of a negative expiratory pressure at the opening of the airways (NEP for negative expiratory pressure). The third is the possibility to verify in a simple fashion the quality of the expiratory performance achieved by the patient and thus to detect an insufficient effort in the force of a falling expiratory flow.

Dyspnea↗
PubMed1987

Effect of effort on measurement of forced expiratory volume in one second.

The American Thoracic Society recommends that the largest FEV1 be reported from a set of forced expiratory vital capacity maneuvers performed with maximal expiratory effort. However, increased expiratory effort can decrease the FEV1. When we evaluated the peak expiratory flow rate (PEFR) in 5 normal subjects, measured from flow-volume curves, as a noninvasive index of expiratory effort, it was positively correlated with indices of effort obtained by using an esophageal balloon. We then measured the difference (dFEV1)between the largest FEV1 and FEV1 from the maneuver with the highest PEFR during 10 test sessions in 10 normal subjects. Thus, dFEV1 was always greater than or equal to 0. The mean dFEV1 was 110 ml for all sessions but decreased to 80 ml when maneuvers with poorly reproducible PEFR or forced expiratory vital capacity values were discarded. We also reviewed 9.471 spirometry sessions from outpatients and found dFEV1 to be greater than 50 ml in 26% of this population and greater than 151 ml in 7%. We concluded that during standard spirometry, FEV1 is inversely dependent on effort. Maximal effort decreases FEV1 because of the effect of thoracic gas compression on lung volume. We recommend that values from spirometry maneuvers that demonstrate submaximal effort, indicated by a decreased PEFR, be discarded. The flow-volume curve display of superimposed efforts facilitates the recognition of submaximal efforts.

Biophysical Phenomena↗
PubMed1990

Tracking of lung function in healthy children and adolescents.

Two hundred twenty-six healthy school children, with a mean age of 8.8 years; 62 girls mean age 8.8, 48 boys mean age 12.6 and 51 girls mean age 12.6 years at the start, were enrolled in a longitudinal study of lung function and tested annually for 5 years. All were free of respiratory symptoms, and none smoked more than five cigarettes per week during the 5 years. Static and dynamic lung volumes (other than residual volume), maximum expiratory and inspiratory flows, and maximum mouth pressures "track," that is, individuals remain at a constant deviation from the sample mean over time. The data indicate that these measurements of lung function in healthy individuals grow in constant proportion relative to other healthy children and adolescents.

Adolescent↗
PubMed1993

Physiologic evaluation of pulmonary function in the candidate for lung resection.

From July 1, 1974, to December 31, 1990, 2340 patients who underwent pulmonary resection were evaluated by comprehensive analysis of pulmonary function. Pulmonary function test criteria for resection were (1) pneumonectomy: forced expiratory volume in 1 second greater than 2 L; forced expiratory flow rate from 25% to 75% greater than 1.6 L; maximum voluntary ventilation greater than 55%; (2) lobectomy: forced expiratory volume in 1 second greater than 1 L; forced expiratory flow rate from 25% to 75% greater than 0.6 L; maximum voluntary ventilation greater than 40%; (3) wedge or segmental resection: forced expiratory volume in 1 second greater than 0.6 L; forced expiratory flow rate from 25% to 75% greater than 0.6 L; maximum voluntary ventilation greater than 35%. Split perfusion lung scan and Reichel exercise stress testing were utilized as indicated. When these values of pulmonary function have been applied, a more precise method of selecting patients for various types of pulmonary resection has resulted in a lower mortality while denying operation to less than 1% of the patients who are considered for surgical resection.

Exercise Test↗
PubMed1996

Effects of lung volume and thoracic gas compression on maximal and partial flow-volume curves.

Comparing isovolume flows, measured at the mouth during forced expiratory manoeuvres as started from maximal or partial lung inflation, is a means of assessing the effects of deep inhalation on airway calibre. The aim of this study was to investigate whether the assessment of the effect of deep inhalation during induced bronchoconstriction is influenced by the lung volume at which it is determined and by volume differences due to thoracic gas compression that occur during forced expiratory manoeuvres. Four healthy subjects and six subjects with mild-to-moderate asthma subjects performed partial and maximal forced expiratory manoeuvres in a flow-type body plethysmograph at control and during a methacholine (MCh) inhalation challenge. Mouth flow (V1) was plotted against both the expired volume (Vmo) and the simultaneous thoracic volume measured by plethysmography (Vpl) changes (V1-Vmo loop and V1-Vpl loop, respectively). The effects of deep inhalation were quantified by determining 1) the ration of maximal to partial expiratory flows (M/P) at 30, 40 and 50% of control forced vital capacity (FVC) both on V1-Vmo loops (M/Pmo) and V1-Vpl loops (M/Ppl) at control and at MCh end-point; and 2) the slope of the linear regression of maximal vs partial expiratory flows at 30, 40 and 50% of control FVC both on V1-Vmo loops (MPst,mo) and V1-Vpl loops (MPsl,pl) over the entire challenge. At control, M/Pmo and M/Ppl were similar. At MCh end-point, M/Pmo and M/Ppl increased more than twofold (p < 0.002), with M/Pmo consistently exceeding M/Ppl (p < 0.001). In addition, both M/Pmo and M/Ppl varied inversely with lung volume (p < 0.001). By contrast, MPsl,mo and MPsl,pl were not significantly different from each other (p = 0.8), and were also similar at the different lung volumes (p = 0.6). We conclude that during induced bronchoconstriction, the bronchodilation following a deep inhalation, expressed as maximal to partial flow ratio is dependent both on lung volume and volume differences due to thoracic gas compression. The use of expired flow and volume measurements may lead to a small but systematic overestimation of the bronchodilator effect of a deep inhalation. On the contrary, maximal to partial flow slope is insensitive either to lung volume or volume differences due to thoracic gas compression and can, therefore, be fairly determined from expired flow-volume loops.

Adult↗
PubMed1995

Gender differences in lung growth.

Annual measurements of lung volumes and forced expiratory flows were made in 281 boys and girls from 8 to 12 years and in another cohort of 287 from 12 to 20 years to measure longitudinal lung growth. Gender differences in growth of lung function were documented, with girls generating greater volume-standardized maximal expiratory flows until age 18.5 years. Beyond that age boys generated higher expiratory flows in proportion to total lung capacity (TLC). There was a time lag of up to 1 year between the age of peak growth velocity in lung volume and peak growth velocity in height. Age at peak growth in flow lagged another year behind that in volume. This was noted more in boys than girls. Dysanaptic lung growth was found with differing rates of growth of maximal expiratory flow compared with TLC or vital capacity (VC).

Adolescent↗
PubMed1996

Pulmonary function after laparoscopic cholecystectomy in the elderly.

The results of laparoscopic cholecystectomy in a group of 52 patients older than 69 years (group 1) were compared with the results of the same operation in a group of 338 younger patients (group 2). In group 1, 23 per cent of patients had acute cholecystitis and 13 per cent were operated on after an episode of acute pancreatitis. In group 2, 8 per cent of patients had acute cholecystitis and 4 per cent were operated on after acute pancreatitis. Pulmonary function was assessed prospectively before operation, 24 h after surgery and on the seventh day after operation, in 20 patients in group 1 and 30 in group 2. In group 1 there was one death (2 per cent); the morbidity rate was 14 per cent and conversion to laparotomy was required in 15 per cent. In group 2 there were no deaths, the morbidity rate was 11 per cent and the conversion rate 4 per cent. No significant differences were found between the two groups in mortality and morbidity rates. Preoperative values of forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were significantly lower in group 1 than in group 2 (P < 0.05); the values of FVC, FEV1 and forced expiratory flow at 50 per cent 24 h after surgery were less depressed in group 1 (P < 0.01) and also recovered more quickly in these patients 7 days after operation. Laparoscopic cholecystectomy gives excellent results in geriatric patients and can be recommended as the treatment of choice for symptomatic cholelithiasis in the elderly.

Aged↗
PubMed1998

Analysis of forced expiratory maneuvers from raised lung volumes in preterm infants.

During recent years it has been suggested that forced expiratory measurements, derived from a lung volume set by a standardized inflation pressure, are more reproducible than those attained during tidal breathing when the rapid thoracoabdominal compression technique is used in infants. The aim of this study was to evaluate the feasibility of obtaining measurements from raised lung volumes in unsedated preterm infants. Measurements were made in 18 infants (gestational age 26-35 wk, postnatal age 1-10 wk, test weight 1.4-3. 5 kg). Several inflations [1.5-2.5 kPa (15-25 cmH2O)] were used to briefly inhibit respiratory effort before the rapid thoracoabdominal compression was performed. Conventional analysis of flows and volumes at fixed times and percentages of the forced expiration resulted in a relatively high variability in this population. However, by using the elastic equilibrium point (i.e., the passively determined lung volume, derived from passive expirations before the forced expiration) as a volume landmark, it was feasible to achieve reproducible results in unsedated preterm infants, despite their strong respiratory reflexes and rapid respiratory rates. Because this approach is independent of changes in expiratory time, expired volume, or applied pressures, it may facilitate investigation of the effects of growth, development, and disease on airway function in infants, particularly during the first weeks of life, when conventional analysis of forced expirations may be inappropriate.

Female↗
PubMed2006

Right ventricular and pulmonary function in sickle cell disease patients with pulmonary hypertension.

The effects of sickle cell disease (SCD) on right ventricular (RV) and pulmonary function in SCD patients with pulmonary hypertension is not well-known. The aim of this study was to investigate RV and pulmonary functions in patients suffering from SCD with or without pulmonary hypertension using color tissue Doppler imaging and spirometry. We evaluated 48 asymptomatic patients with SCD. All patients underwent echocardiography with tissue Doppler imaging and pulmonary function test. Patients were divided into two groups: Group 1 consisted of 27 patients (age, 18.1 +/- 7.1 years) with normal pulmonary artery pressure, and group 2 consisted of 21 patients (age, 21.4 +/- 7.4 years) with pulmonary hypertension. Both groups were compared with a sex- and age-matched control group including 24 normal healthy subjects (age, 19.8 +/- 9.2 years). Tricuspid lateral annular systolic (S (m)) and early diastolic velocity (E (m)) were higher in group 1 than group 2 and the control group (p < 0.05). Tricuspid lateral annular late diastolic velocities (A (m)), isovolumetric contraction time, and myocardial performance index (MPI) were higher and the E (m)/A (m) ratio was lower in group 2 than group 1 and the control group (p < 0.05). However, no differences were found in the tricuspid lateral annular E (m) deceleration time, ejection time, and isovolumetric relaxation time between group 1, group 2, and the control group. Tricuspid lateral annular S (m) and E (m) were similar in group 2 and the control group. Forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and the diffusion capacity of the lung for carbon monoxide were decreased in both groups of patients compared to the control group (p < 0.05). However, there was no difference in respiratory rate, FEV(1)/FVC ratio, peak expiratory flow, and total lung capacity between group 1, group 2, and the control group. There were no differences in any indices of lung function between the two groups of patients. MPI is useful index to evaluate RV function in patients with SCD. RV diastolic function was disturbed in only SCD patients with pulmonary hypertension. On the other hand, the restrictive pattern of pulmonary function abnormalities had developed in both groups of patients.

Adolescent↗
PubMed1977

[Significance of contemporary methods of lung function testing for the detection of airway obstruction in children and adolescents (author's transl)].

In the article we outlined the basic principles of some recent methods of lung function testing, suitable for the assessment of airway obstruction in children and adolescents. There is also a brief description of various methods, normal values expressed in a form of regression equations, significance of different methods for the assessment of airway obstruction in patients with respiratory diseases and in children from a region with increased levels of air pollution. Among the various functional indices we found the most sensitive for the assessment of airway obstruction maximum expiratory flow rates measured at lower lung volume levels. Airway conductance appeared as the most sensitive method for the evaluation of bronchodilation following inhalation of some drugs. The measurements of airway conductance in a body plethysmography during normal quiet breathing and of maximum expiratory flow rates from flow-volume curves represent the basic methods for the detection of airway obstruction, i.e. in the larger central airways, and in the peripheral airways respectively.

Adolescent↗
PubMed1979

Determination of bronchodilation in the clinical pulmonary function laboratory. Role of changes in static lung volumes.

Improved airway resistance following bronchodilator inhalation is not always accompanied by improvement in forced expiratory flow. We studied 241 patients with airways obstruction to learn whether changes in static lung volumes (vital capacity and function residual capacity measured by body plethysmography [FRCB]) would reveal bronchodilation not demonstrated by expiratory flow rates (the ratio of forced vital capacity at one second to the total forced vital capacity [FEV1/FVC]), and the forced expiratory flow for the midportion of the forced vital capacity (FEF25--75%). A significant fall in Raw occurred in 129 patients, 46 of whom had a significant increase in vital capacity (mean of + 465 ml +/- 43, P less than 0.001) and a fall in FRCB (mean of -763 ml +/- 78 P less than 0.001) with no change in FEV1/FVC% of FEF25--75%. We interpret these data to indicate that improvement in static lung volumes can reflect bronchodilation in the absence of improved expiratory flow.

Adult↗
PubMed2000

The concentration of hydrogen peroxide in exhaled air depends on expiratory flow rate.

Hydrogen peroxide (H2O2) is known to be detectable in exhaled air. The present study aimed to determine whether the concentration of exhaled H2O2 depends on expiratory flow rate in order to make inferences on the site of its production within the lung. Breath condensate was collected in cooled Teflon tubes, at three different expiratorv flow rates, in 15 healthy or mild asthmatic subjects. Tests were repeated 2-5 times to assess reproducibility. Mean+/-SEM concentrations of H2O2 at flow rates of 140, 69 and 48 mL.s(-1) were 0.12+/-0.02, 0.19+/-0.02 and 0.32+/-0.03 microM, respectively. These values differed significantly from each other (p<0.001). For comparison, average coefficients of variability within repeated measurements at each of the three flow rates were 68, 62 and 82%, respectively. These data demonstrate that the concentration of exhaled hydrogen peroxide depends on expiratory flow rate. Since flow dependence is an indicator of production within the airways, this result suggests that, to a large extent, the exhaled hydrogen peroxide originates within the airways. However, even under strictly controlled conditions, a high degree of variability persists, which may limit the usefulness of exhaled hydrogen peroxide as a marker of airway inflammation.

Adult↗
PubMed2000

Assessment and monitoring of flow limitation and other parameters from flow/volume loops.

Flow/volume (F/V) spirometry is routinely used for assessing the type and severity of lung disease. Forced vital capacity (FVC) and timed vital capacity (FEV1) provide the best estimates of airflow obstruction in patients with asthma, chronic obstructive pulmonary disease (COPD) and emphysema. Computerized spirometers are now available for early home recognition of asthma exacerbation in high risk patients with severe persistent disease, and for recognition of either infection or rejection in lung transplant patients. Patients with severe COPD may exhibit expiratory flow limitation (EFL) on tidal volume (VT) expiratory F/V (VTF/V) curves, either with or without applying negative expiratory pressure (NEP). EFL results in dynamic hyperinflation and persistently raised alveolar pressure or intrinsic PEEP (PEEPi). Hyperinflation and raised PEEPi greatly enhance dyspnea with exertion through the added work of the threshold load needed to overcome raised pleural pressure. Esophageal (pleural) pressure monitoring may be added to VTF/V loops for assessing the severity of PEEPi: 1) to optimize assisted ventilation by mask or via endotracheal tube with high inspiratory flow rates to lower I:E ratio, and 2) to assess the efficacy of either pressure support ventilation (PSV) or low level extrinsic PEEP in reducing the threshold load of PEEPi. Intraoperative tidal volume F/V loops can also be used to document the efficacy of emphysema lung volume reduction surgery (LVRS) via disappearance of EFL. Finally, the mechanism of ventilatory constraint can be identified with the use of exercise tidal volume F/V loops referenced to maximum F/V loops and static lung volumes. Patients with severe COPD show inspiratory F/V loops approaching 95% of total lung capacity, and flow limitation over the entire expiratory F/V curve during light levels of exercise. Surprisingly, patients with a history of congestive heart failure may lower lung volume towards residual volume during exercise, thereby reducing airway diameter and inducing expiratory flow limitation.

Asthma↗
PubMed1987

Accuracy of spirometric and flow-volume indices obtained by digitizing volume-time tracings.

We tested the accuracy of a new system for deriving standard spirometric indices, maximal expiratory flow rates, and slope ratios from volume-time tracings. A computer-based technique employing a hand-operated cursor was used to put discrete values of volume and time into a memory array. Spirometric values obtained on 102 subjects using the computer system were compared with the corresponding "hand-read" values. The difference between the 2 measuring techniques were not significant for the FVC, the FEV75, and the FEF25-75; however, the average FEV1 differed by 6.7 ml (SD, 20.3 ml), which was significant. In addition, 10 subjects performed FVC maneuvers through a spirometer and flowmeter connected in series. Flows and slope ratios obtained from the volume-time tracings were compared with those obtained directly from the flowmeter. There was a high degree of correlation between the 2 types of flow measurements (r = 0.989), whereas slope ratios were less well correlated (r = 0.589). Configurational detail such as the presence of "bumps" on slope ratio versus volume plots were recovered with the computer technique. Using this new system, it is possible for 1 operator to process 10 to 12 sets of spirometry tracings per hour.

Adolescent↗
PubMed1982

Discriminant analysis of pulmonary function parameters. Healthy adults versus mild asthmatics and moderate asthmatics.

Volume-time (V-T) and flow-volume (F-V) curves were measured in all the subjects of nonsmoking young males (mean value 26.3 yrs. of age), healthy and asthmatics. Eleven parameters of pulmonary function tests composed of two V-T, six F-V, and three mean time constant (MTC) parameters, were calculated from the curves. These parameters were used in the two analyses through the all possible selection procedure (APSP) discriminating between healthy adults and mild asthmatics and also between healthy and moderate. Flow rate at 75% of FVC (V75) proved to be the most useful parameter and V50 the next best in both analyses. The probability of misclassification using all eleven parameters was 19.64% in the analysis of healthy adults and mild asthmatics, and 4.29% in the analysis of healthy adults and moderate asthmatics. There was a little difference in the parameters selected at every step. The discriminant analysis proved that the flow-volume patterns were different according to the severity of bronchial asthma. Thus flow-volume recognition was considered to be important in analyzing the severity of bronchial asthma.

Adult↗