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PubMed1990

[Effect of deep inspiration on maximum expiratory flow (Vmax) depends on basal bronchomotor tone in young healthy females].

The relationship between the effect of deep inspiration on Vmax and basal bronchomotor tone was studied by partial and maximum expiratory flow-volume curve in 16 young healthy females (20-21 years old). Effect of deep inspiration on Vmax (DI index; (PEF25-MEF25)/PEF25) significantly related to percent increase in PEF25 not only by inhalation of ipratropium bromide (r = 0.81, p less than 0.0002) but also by inhalation of salbutamol (r = -0.62, p less than 0.01). Furthermore, day to day variation of DI index significantly related to day to day variation of PEF25 (r = 0.68, p less than 0.005) but not to that of MEF25. These findings suggest that the bronchodilating effect of deep inspiration in young healthy females may depend on intensity of basal bronchomotor tone caused by tonic vagal nerve activity.

Adult↗
PubMed1995

[Chronic hyperventilation syndrome. The role of respiratory re-training].

This study compares three non-pharmacological approaches to the chronic hyperventilation syndrome (CHS). Eighteen subjects were evaluated at the start of the study then one and 6 months after having received in a random fashion one of the following treatments: group I (teaching approach of one hour on the respiratory physiology of the CHS and on breathing techniques; n = 5); group II (same approach as in group I with breathing retraining of 8 sessions; n = 8); group III (same as group II with the addition of a modified Jacobson's progressive relaxation; n = 5). Whereas all three groups had a similar symptomatic score at the beginning of the study (although subjects of group III had in general higher scores and were symptomatic for a longer period), our results show that all subjects improved after 4 weeks, those in group II showing the greatest improvement (p < 0.05). This confirms the relevance of applied and repeated pedagogy in approaching subjects with the CHS.

Adolescent↗
PubMed1976

The effect of CO2 on peripheral airways.

In each of ten healthy young subjects breathing different concentrations of CO2 in O2, four alveolar CO2-tension levels were obtained, ranging from about 20 mmHg when hyperventilating in O2 to 50 mmHg. Maximum expiratory flows at 60% total lung capacity were measured at each level and corrected for the influence of the expired gas on the flow. The corrected maximum flow decreased significantly when the alveolar CO2 tension was below 30-35 mmHg, while there was only slight or no influence of CO2 on the maximal flow when the tension was above 35 mmHg. The decrease is taken as evidence of a constrictor effect on peripheral bronchi of hypocapnia.

Adult↗
PubMed1980

Evaluation of pulmonary mechanics in guinea pigs during respiratory anaphylaxis.

Guinea pigs sensitized to ovalbumin exhibit signs of respiratory impairment when exposed to an aerosol of the antigen. This response was investigated in anesthetized guinea pigs by determining forced pulmonary mechanics to derive peak expiratory flow rate, forced vital capacity, forced expiratory volume in 0.1 sec, maximal mid-expiratory flow rate and respiratory rate. Measurement of these parameters allows qualitative comparisons to be made with changes that are routinely determined during investigations of human asthma. Exposure of anesthetized guinea pigs to a 3% ovalbumin aerosol for 2 min produced an increase in respiratory rate, a 20% fall in peak expiratory flow rate and maximal mid-expiratory flow rate, a 50% fall in forced vital capacity and a 40% fall in forced expiratory volume in 0.1 sec. This response was reversed by aminophylline. In these respects the response appears to be similar to the acute asthmatic response in humans.

Aminophylline↗
PubMed1975

Comparison of the cardiopulmonary effects of subcutaneously administered epinephrine and terbutaline in patients with reversible airway obstruction.

The cardiopulmonary effects of epinephrine and terbutaline were compared in a doubleblind crossover study in 23 subjects with chronic obstructive airway disease. On each of three days each subject received a single subcutaneous dose of saline, 0.25 mg of epinephrine or 0.5 mg of terbutaline. Treatment with epinephrine produced significant increases in forced vital capacity (FVC), forced expiratory volume in one second (FEV-1), maximal expiratory flow rate (MEFR) and maximal mid-expiratory flow (MMEF). Terbutaline caused even more pronounced increases in all four parameters and exhibited a longer duration of action. Neither drug altered arterial pH, arterial oxygen pressure (PaO-2), or arterial carbon dioxide pressure (PaCO-2). With regard to cardiovascular effects, no alterations in either systolic or diastolic pressure were observed. Administration of epinephrine and terbutaline caused statistically significant increases in heart rate. The effect of terbutaline was more pronounced that that of epinephrine. In addition, terbutaline caused a heart rate-related depression of the T-wave of the lead 2 ECG. Neither drug altered any of the hematologic, hemochemical or urinary parameters monitored before and after treatment. Side effects were seen in eight subjects after administration of saline solution, in 13 subjects after epinephrine and in 19 subjects after terbutaline. None of these side effects was considered clinically serious and none required treatment. It is concluded from this study that subcutaneously administered terbutaline is a more effective bronchodilator than epinephrine.

Adult↗
PubMed1992

[The effect of epidural analgesia on respiratory muscles].

The effect of epidural analgesia on respiratory functions and muscular power was studied in patients. The subjects had no abnormality of cardiopulmonary system, and were classified into two groups; the adult group whose ages were 21 to 59, and the aged group, 60 to 72. Either 1% or 2% mepivacaine for epidural anesthesia was used to obtain the analgesic level up to Th4 and Th7 in adult group, and Th4 in aged group. The analgesic level was assessed by the pin-prick method. Vital capacity, forced vital capacity, forced expiratory volume 1 second, peak expiratory flow rate, maximal mid-expiratory flow rato, maximal inspiratory pressure and maximal expiratory pressure decreased significantly after epidural anesthesia in all patients whose analgesic levels were up to Th4. In all patients, the change of maximal expiratory pressure was larger than that of maximal inspiratory pressure after epidural analgesia. The patients whose analgesic levels were up to Th7 by 1% mepivacaine in adult group, showed a significant increase of maximal inspiratory pressure. It is concluded that epidural anesthesia diminishes respiratory functions and respiratory muscular power associated with a higher level of analgesia.

Adult↗
PubMed1976

Effect of volume history on successive partial expiratory flow-volume maneuvers.

In normal subjects, the second of two successive partial expiratory flow-volume (PEFV 2) curves often had higher isovolume maximal expiratory flow rates (Vmax) than the first (PEFV 1) (mean increase 30.2 +/- 13%). The higher Vmax on PEFV 2 was present only when there was a greater lung elastic recoil pressure (Pst(L)). In eight subjects the Pst(L) derived from sequential partial quasi-static pressure-volume curves, from interruption of the flow-volume maneuvers and at the start of the PEFV curves showed that isovolume upstream resistance increased although Vmax also increased after going to residual volume (RV). In four subjects the RV volume history did not change the pressure flow relationship across the upstream airways. If airways dimensions were the sole determinant of Vmax, then Vmax on PEFV 2 would be the same or smaller than on PEFV 1. That the opposite was observed in our study indicates that the increase in Pst(L), which results from parenchymal hysteresis, offsets any dimensional decrease in upstream airways due to airways hysteresis.

Adult↗
PubMedDate not supplied

[Calisthenics as a preventive measure against the decrease in maximum expiratory flow in asthmatic patients before and after a soccer game].

BACKGROUND: Exercise-induced asthma is a syndrome characterized by dyspnea, thoracic pain, cough, sibilant rales and diminished physical performance. It appears into the first 30 minutes after the beginning of physical activity. OBJECTIVE: To evaluate calisthenic effect on maximal expiratory flow rate in asthmatic patients. MATERIAL AND METHODS: A prospective, observational and descriptive study was done through a soccer game. Male and female asthmatic patients from 6 to 16 years old with intermittent and mild asthma were included. Maximal expiratory flow rate was measured before the beginning of soccer game, and then, at the end of the first and second sets. Statistical analysis was made through the media values comparison and t Student test. RESULTS: 60 patients were included. They were 11.3 +/- 2.4 mean aged. 45% had diagnosis of mild asthma, 36.6% mild asthma and allergic rhinitis and 6.6% persistent asthma. Average of basal maximal expiratory flow rate was 275 +/- 90 L/s, and no significant changes were observed in 52 patients: mean maximal expiratory flow rate at the end of first and second sets was 275 +/- 86 L/s and 273 +/- 96 L/s, respectively. Maximal expiratory flow rate diminished at 77 +/- 3.8% and 83 +/- 9.5% in the other eight patients at the end of the first and second sets, respectively. CONCLUSIONS: Calisthenic made before physical activity prevents maximal expiratory flow rate diminishment.

Adolescent↗
PubMed1990

Effect of age on changes in flow rates and airway conductance after a deep breath.

The effects of aging on changes in maximal expiratory flow rates and specific airway conductance after a deep breath were evaluated in 64 normal subjects. Flow rates (Vp) on partial expiratory flow-volume curves (PEFV), initiated from 60-70% of the vital capacity (VC), were compared with those (Vc) on maximal flow-volume curves (MEFV), initiated from total lung capacity (TLC), at a lung volume corresponding to 25% of VC on the MEFV curves. Specific airway conductance was measured before (sGaw) and after a deep inspiration (sGawDI). Bronchodilation after inspiration to TLC was inferred by Vp/Vc less than 1 and sGaw/sGawDI less than 1. The mean Vp was less than Vc. However, the ratio Vp/Vc increased significantly with age (r = 0.75, P less than 0.001). Specific conductance also increased after a deep inspiration (sGaw less than sGawDI). The ratio sGaw/sGawDIj increased slightly but significantly with age (r = 0.28, P less than 0.02). Measurement of lung elastic recoil pressures before and after a deep breath in a subgroup of patients (n = 14) suggested that the age-related increase in Vp/Vc was secondary to a decrement in the ability of a deep breath to decrease the upstream airway resistance. These findings suggest that even though changes in airway size after a deep breath as measured by sGaw/sGawDI have minimal age dependence, aging diminishes expiratory flow rates of MEFV curves relative to PEFV curves because of a decrease in the ability of a deep breath to increase the size of the peripheral airways.

Adolescent↗
PubMed1977

A new simple spirometric index for use with bronchial provocation tests.

Spirometric indices such as the forced expiratory volume in one second (FEV1), the maximal expiratory flow rate (MEFR) and the maximal midexpiratory flow rate (MMFR) can be criticized for use with bronchial provocation tests since they are either partly effort-dependent or dependent on the forced vital capacity (FVC). These criticisms can be avoided by the use of a new index corresponding to the volume of air expired in one second starting at 75% of the control FVC, called the (FEV1)-25. This study was performed to evaluate the relative sensitivity of the (FEV1)-25 and the classical FEV1 in detecting airway obstruction caused by an inhaled carbachol aerosol in 20 asthmatic subjects. The mean fall in (FEV1)-25 of 46% following carbachol inhalation compared with a mean fall in FEV1 of 35% indicates that, in addition to its theoretical advantages, the (FEV1)-25 is a sensitive index for use with bronchial provocation tests.

Adolescent↗
PubMed2003

Comparison of maximal midexpiratory flow rate and forced expiratory flow at 50% of vital capacity in children.

BACKGROUND: The mid-portion of the maximal expiratory flow-volume (MEFV) curve is often described by values of the mean forced expired flow as lung volume decreases from 75% to 25% of vital capacity (ie, forced expiratory flow, midexpiratory phase [FEF(25-75)]). It is common practice to report also forced expired flow at 50% of vital capacity (FEF(50)). STUDY OBJECTIVE: To investigate whether FEF(50) and FEF(25-75) are highly correlated or whether the difference between them reflects a degree of airways obstruction. Also, we wanted to investigate the correlation between the two in cases of irregularly shaped MEFV curves (ie, "saw-toothing"). DESIGN: Analysis of the correlation between FEF(50) and FEF(25-75) in a single determination. We assessed the relationship between the FEF(50)/FEF(25-75) ratio and the degree of airways obstruction, as reflected by other traditional parameters such as FEV(1), FEV(1)/FVC ratio, and specific airway conductance (SGaw). PATIENTS: There were 1,350 forced expiratory maneuvers performed by children with a broad range of pulmonary abnormalities. RESULTS: FEF(50) correlated with FEF(25-75) as follows: FEF(50) (L/s) = 0.041 + 1.136*FEF(25-75)(L/s); r(2) = 0.956; standard error of the estimate = 0.013; p < 0.0001. The FEF(50)/FEF(25-75) ratio remained stable and did not correlate with FEV(1) (r = 0.12), FEV(1)/FVC ratio (r = 0.11), or SGaw (r = 0.02; difference not significant). The correlation between FEF(25-75) and FEF(50) was similar for both the smooth curve (r = 0.97) and the irregular curve (r = 0.96). CONCLUSIONS: Although not identical, FEF(25-75) and FEF(50) are highly correlated, and the ratio of the two is fairly constant. Therefore, the practice of reporting both of them is unnecessary. We suggest that it is reasonable to prefer FEF(50).

Child↗
PubMed1986

Relationship between lung volume, maximal expiratory flow, forced expiratory volume in one second, and tracheal area in normal men and women.

Tracheal area at different lung volumes was measured using acoustic reflection technique, flow-volume curves, and lung volumes by body plethysmography in 24 healthy adults (14 men, 10 women) in order to study the relationship between tracheal area and lung volume, and between tracheal area and maximal expiratory flow rates. Each individual tracheal area was greatest at TLC and lowest at RV; this lung volume dependence was significantly greater in men than in women. When tracheal areas versus absolute lung volumes were plotted for the entire group and the linear regression analysis on the data was performed, no significant correlation between lung volume and tracheal area in men was found, but a highly significant correlation was found in women. Using the analysis proposed by Mead (Am Rev Respir Dis 1980; 121:339-42) in his assessment of dysanapsis, the ratio of tracheal area/lung volume versus lung volume was plotted and the slope was found to be negative (and close to -1) in men and positive in women. Therefore it was concluded that the relationship between tracheal area and lung volume is consistent with the hypothesis that in men and women lung parenchyma grows independently of the airways; furthermore, in women the airways grow faster than the lung parenchyma. In addition, in women there was good correlation between tracheal area and FEV1, as well as maximal expiratory flow rates at 50 and 25% of VC. For men, these correlations were less consistent and depended on the lung volume at which tracheal area was measured.

Adult↗
PubMed1988

Serial relationships between ventilation-perfusion inequality and spirometry in acute severe asthma requiring hospitalization.

Patterns of VA/Q distribution and their relationship to spirometric indices were studied in 10 patients with acute severe asthma requiring hospitalization (7 women and 3 men 41.0 +/- 5.6 yr of age, mean +/- SEM) on admission and during subsequent recovery. On admission, all patients received the standard therapeutic regimen for our hospital. Spirometry and essentially noninvasive multiple inert gas elimination measurements were obtained serially, approximately once every day, whereas conventional arterial blood gases were determined every 3 days. On admission, all patients showed severe air-flow obstruction (FEV1/FVC% = 34.1 +/- 4.3%) and moderate to severe hypoxemia without CO2 retention (PaO2 = 50.5 +/- 2.6 mm Hg; PaCO2 = 37.1 +/- 2.4 mm Hg; AaPO2 = 53.7 +/- 3.0 mm Hg). Nine of the 10 patients showed bimodal blood flow distributions (dispersion of blood flow distribution, log SD Q = 1.34 +/- 0.11; normal range, 0.3 to 0.6) with only small amounts of shunt (1.09 +/- 0.8%). However, no significant interindividual correlations were observed between maximal expiratory flow rates (FEV1 and FEF25(-75) and log SD Q (r2 = 0.14 and 0.006, respectively). This lack of correlation persisted throughout hospitalization. Despite both clinical and spirometric improvement in all patients, there was simultaneous improvement in VA/Q matching in only one patient. Statistically significant negative correlations between maximal expiratory flow rates and gas exchange did develop toward the end of the study (Weeks 3 and 4 after discharge) when maximal recovery of physiologic changes associated with the acute asthma attack was achieved.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed2002

Lung function over six years among professional divers.

AIMS: To analyse longitudinal changes in pulmonary function in professional divers and their relation with cumulative diving exposure. METHODS: The study included 87 men at the start of their education as professional divers. At follow up one, three, and six years later, 83, 81, and 77 divers were reexamined. The median number of compressed air dives in the 77 divers over the follow up period was 196 (range 37-2000). A group of non-smoking policemen (n = 64) were subjected to follow up examinations in parallel with the divers. Assessment of lung function included dynamic lung volumes, maximal expiratory flow rates, and transfer factor for carbon monoxide (Tl(CO)). The individual rates of change of the lung function variables were calculated by fitting linear regression lines to the data, expressed as percent change per year. RESULTS: The annual reductions in forced vital capacity (FVC) and forced expired volume in one second (FEV(1)) were 0.91 (SD 1.22) and 0.84 (SD 1.28) per cent per year in divers, which were significantly higher than the reductions in the policemen of 0.24 (SD 1.04) and 0.16 (SD 1.07) per cent per year (p < 0.001). The annual reduction in the maximal expiratory flow rates at 25% and 75% of FVC expired (FEF(25%) and FEF(75%)) were related to the log(10) transformed cumulative number of dives in a multiple regression analysis (p < 0.05). The annual reductions in Tl(CO) were 1.33 (SD 1.85) and 0.43 (SD 1.53) per cent per year in divers and policemen (p < 0.05). CONCLUSIONS: FVC, FEV(1), maximal expiratory flow rates, and Tl(CO) were significantly reduced in divers over the follow up period when compared with policemen. The contrasts within and between groups suggest that diving has contributed to the reduction in lung function.

Accidents, Occupational↗
PubMed1998

Smaller lungs in women affect exercise hyperpnea.

We subjected 29 healthy young women (age: 27 +/- 1 yr) with a wide range of fitness levels [maximal oxygen uptake (VO2 max): 57 +/- 6 ml . kg-1 . min-1; 35-70 ml . kg-1 . min-1] to a progressive treadmill running test. Our subjects had significantly smaller lung volumes and lower maximal expiratory flow rates, irrespective of fitness level, compared with predicted values for age- and height-matched men. The higher maximal workload in highly fit (VO2 max > 57 ml . kg-1 . min-1, n = 14) vs. less-fit (VO2 max < 56 ml . kg-1 . min-1, n = 15) women caused a higher maximal ventilation (VE) with increased tidal volume (VT) and breathing frequency (fb) at comparable maximal VT/vital capacity (VC). More expiratory flow limitation (EFL; 22 +/- 4% of VT) was also observed during heavy exercise in highly fit vs. less-fit women, causing higher end-expiratory and end-inspiratory lung volumes and greater usage of their maximum available ventilatory reserves. HeO2 (79% He-21% O2) vs. room air exercise trials were compared (with screens added to equalize external apparatus resistance). HeO2 increased maximal expiratory flow rates (20-38%) throughout the range of VC, which significantly reduced EFL during heavy exercise. When EFL was reduced with HeO2, VT, fb, and VE (+16 +/- 2 l/min) were significantly increased during maximal exercise. However, in the absence of EFL (during room air exercise), HeO2 had no effect on VE. We conclude that smaller lung volumes and maximal flow rates for women in general, and especially highly fit women, caused increased prevalence of EFL during heavy exercise, a relative hyperinflation, an increased reliance on fb, and a greater encroachment on the ventilatory "reserve." Consequently, VT and VE are mechanically constrained during maximal exercise in many fit women because the demand for high expiratory flow rates encroaches on the airways' maximum flow-volume envelope.

Adolescent↗
PubMed1980

Maximal mid-inspiratory to maximal mid-expiratory flow rate ratio in upper airway obstruction.

The maximal mid-inspiratory to maximal mid-expiratory flow rate ratio (MMIF/MMEF) was measured in 16 patients with upper airway obstruction, in eight with pleural disease, in 25 with chest wall abnormalities, in 64 with various lung diseases and in 28 normal subjects. MMIF/MMEF ratio values of less than 1.0 were recorded in eight out of 16 patients with upper airway obstruction, in nine out of 25 patients with chest wall abnormalities and in one normal subject. Our findings show that a MMIF/MMEF ratio less than 1.0 although suggestive, is not diagnostic of upper airway obstruction. However, reduced MMIF/MMEF ratio in the presence of airflow obstruction is specific in localizing obstruction to the upper airway.

Airway Obstruction↗