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PubMed1986

The effect of transfusion on lung capacity, diffusing capacity, and arterial oxygen saturation in patients with thalassemia major.

Our previous cross-sectional study of patients with thalassemia major suggested progressive lung changes characterized by low total lung capacity, hypoxemia, and elevated transfer factor for carbon monoxide. We reevaluated nine of the patients for three reasons: to determine the relationship of the previous findings to the immediate effects of blood transfusion; to assess the longitudinal progression of the lung changes; and to evaluate the effect of splenectomy on lung volume changes in these patients, all of whom underwent splenectomy in the interval between the two studies. We found that during the 5- to 6-yr period between studies total lung capacity had decreased significantly (p less than 0.05) from a mean 86% predicted to a mean 79% predicted. However, vital capacity increased significantly (p less than 0.05) from a mean 81% predicted to 88% with no significant change in functional residual capacity. There was no significant immediate effect of transfusion on total lung capacity, vital capacity, or functional residual capacity. However, the diffusion constant for carbon monoxide increased significantly (p less than 0.005) immediately following transfusion and there was a positive correlation between the increase and the amount of blood transfused (r = 0.74, p less than 0.05). Arterial oxygen saturation was below 95% in five of eight patients and increased significantly with transfusion (p less than 0.05). We conclude: 1) thalassemia major and/or its treatment is associated with hypoxemia and a progressive reduction in total lung capacity. 2) Despite the progressive reduction in total lung capacity, splenectomy in patients with thalassemia major increases expiratory reserve volume and thereby increases vital capacity.

Adolescent↗
PubMed1996

Effect of lung volume on the respiratory action of the canine sternomastoid.

We tested the hypothesis that because the resting length of the canine sternomastoid (SM) muscles is relatively insensitive to lung volume change, the SM may maintain its inspiratory force generation regardless of lung volume. The relationships between SM pre- and postcontraction in situ fiber lengths and SM-produced inspiratory pressure generation [i.e., esophageal (Pes)] and rib cage displacements were examined in adult supine anesthetized dogs at residual volume (RV), functional residual capacity, and total lung capacity. SM muscle contraction was produced by isolated bilateral supramaximal electrical stimulation during hyperventilation-induced apnea. In all animals, SM contraction produced negative change in Pes (i.e., an inspiratory action). Passively increasing lung volume from RV to total lung capacity decreased (P < or = 0.01) the SM-produced Pes by -66 +/- 4% but had a relatively small effect on SM in situ pre- and postcontraction fiber length (< 3%). Whereas SM contraction at RV produced a cranial displacement of the sternum and increased the upper rib cage cross-sectional area, passively elevating lung volume diminished the SM-produced expansion of the upper rib cage. Hyperinflation did not increase the impedance of the sternum to cranial displacement during SM contraction, suggesting that hyperinflation caused a dissociation between the mechanical action of the sternum and the upper rib cage. These results suggest that mechanical dissociation of the ribs and sternum may diminish the contribution of the SM to inspiratory volume generation when breathing is done from elevated end-expiratory lung volumes.

Animals↗
PubMed1979

A four-year follow-up study of lung mechanics in smokers.

We performed a prospective study of pulmonary function in 21 smokers, 9 ex-smokers, and 12 nonsmokers. The smokers and ex-smokers were preselected, because they were participants in a smoking cessation clinic. An average interval of 4 years separated the first and second (follow-up) studies. The smoking group showed a significant decrease in maximal expiratory flow measured at low lung volume, loss of elastic recoil, increase in lung compliance, increase in total lung capacity; increase in the ratio of residual volume to total lung capacity, and an increase in the ratio of functional residual capacity to total lung capacity. The ex-smokers showed changes similar to those of the smokers, but of lesser magnitude. The nonsmoking group demonstrated few changes in function during the study interval. Commonly measured parameters of function, including the ratio of the forced expiratory volume in 1 sec to the forced vital capacity and the maximal expiratory flow after exhalation of 50 per cent of the vital capacity, did not change significantly in any group. Sensitive tests of lung function were abnormal in a very high percentage of the combined group of smokers and ex-smokers when measured at the time of the second study; only a small number of abnormalities in these parameters were noted in the nonsmoking group. We conclude that there was a deterioration of lung function in smokers far in excess of that predicted by age. These changes suggest the development of emphysema and were predictable for the group as a whole by a high prevalence of abnormality of dynamic compliance, closing volume, maximal mid-expiratory flow, and residual volume at the time of the initial study.

Adult↗
PubMed1982

Relation between severity of mitral valve disease and results of routine lung function tests in non-smokers.

The effects of mitral valve disease on lung function have been studied in 26 non-smoking patients by relating values for lung volumes and carbon monoxide transfer factor (TLCO) to various indices of cardiac function measured at catheterisation. In general, more severe mitral disease was associated with greater abnormalities of lung function. Reductions of the one-second forced expiratory volume, vital capacity, TLCO and transfer coefficient, and increase in residual volume were all significantly related to the severity of mitral valve disease. In addition, the cardiothoracic ratio, measured radiographically, showed an inverse correlation with both vital capacity and total lung capacity. Although some of the consequences of mitral valve disease on lung function resemble those of primary airway disease, useful distinguishing points are the relative normality of the forced expiratory ratio and the absence of an increase in total lung capacity.

Adult↗
PubMed1982

The influence of lung volume on gas transfer in scoliosis.

Single-breath carbon monoxide transfer factor (DLCO) and diffusion coefficient (KCO) have been compared with vital capacity and total lung capacity in 119 subjects with scoliosis, 74 with idiopathic scoliosis, 32 with congenital osteogenic scoliosis and 13 with paralytic scoliosis. In each group mean values of DLCO were below, and for KCO above, predicted values. Furthermore, in each group, DLCO was correlated with lung volume and KCO inversely correlated with lung volume. The reduction in DLCO is probably due to the reduction in the total alveolar surface area and the increased values for KCO probably result from an increase in pulmonary capillary blood volume per unit alveolar volume at low lung volumes.

Adolescent↗
PubMed1999

The diaphragmatic compound muscle action potentials (DCMAPs) at different lung volumes--a prospective electrophysiological study of the respiratory system.

Phrenic nerve conduction study and measurements of static lung volumes such as functional residual capacity (FRC), total lung capacity (TLC) and residual volumes (RV) using body plethysmography were carried out in 31 normal healthy male subjects (31 +/- 8 years). The objective was to correlate changes in latency, amplitude, duration and area of diaphragmatic compound muscle action potential (DCMAPs) with lung volumes and changes in them with changes in postures. The mean phrenic nerve latency did not show any significant change with lung volumes or postures, but the latency and height of the subject had a significant correlationship (r = 0.68). The peak to peak amplitude of DCMAP showed a significant relationship with the quantitative lung volumes (r = 0.65). The amplitude was significantly higher and duration reduced (p < 0.001) at TLC as compared with those at measured FRC and RV in both sitting and supine postures. The area under the curve did not change significantly. Similarly, amplitudes and latency did not show any significant relation with other anthropometric parameters. The study evaluates a new quantitative relationship between DCMAPs amplitude and lung volumes. This may be carefully used along with other clinical parameters in critically ill patients for an early weaning from ventilator. Posture exerts minimal influence on DCMAPs amplitude; since DCMAPs amplitudes depends on the position of the diaphragm which in turn depends on dipolic potential, its electromagnetic fields and its moving angle subtends at the recording electrode, one can confidently use it to predict lung volume in respiratory failure due to neuromuscular diseases where subjective lung function assessment is impossible. However, a further study is in process in the critical care unit to confirm its utility.

Action Potentials↗
PubMed1995

Pulmonary function alterations after 3 wk of exposure to hypobaria and/or hypoxia in growing rats.

We studied lung growth in rats between 4 and 7 wk of age under different conditions. There were five groups, seven animals in each: 1) general controls (ambient pressure and room air, food ad libitum); 2) hypobaric normoxic [barometric pressure (PB) 410 mmHg, PO2 153 Torr]; 3) normobaric hypoxic (ambient pressure, PO2 80 Torr); 4) hypobaric hypoxic (PB 410 mmHg, PO2 80 Torr); and 5) weight-matched controls to hypobaric hypoxic. Residual volume, functional residual capacity, vital capacity, and total lung capacity grew 10-20% more in both hypoxic groups than in weight-matched and general controls. Expiratory flow rates corrected for forced vital capacity decreased, and specific airway resistance increased significantly. In addition, the ratio of forced expiratory volume in 0.1 s to %forced vital capacity, peak expiratory flow rate, and forced maximal midexpiratory flow were also lower in normobaric hypoxic animals compared with weight-matched controls. Above a transpulmonary pressure of 6 cmH2O, flows were reduced in both hypoxic groups. No differences were observed between hypobaric normoxic and general control groups for lung volume and lung function. In weight-matched animals, total lung capacity decreased but lung function remained unchanged. We conclude that accelerated lung growth in hypobaric hypoxia and normobaric hypoxia is dysanaptic. Lung growth in hypobaric hypoxia is primarily induced by low oxygen, but differences between hypobaric hypoxia and normobaric hypoxia suggest a beneficial effect of low pressure.

Animals↗
PubMed1985

Phrenic and diaphragm function after coronary artery bypass grafting.

We studied respiratory mechanics and phrenic nerve and diaphragm function in 12 patients on the day before and eight to 13 days after coronary artery bypass grafting. The average vital capacity, functional residual capacity, and total lung capacity decreased by 20.5%, 9.5%, and 14.7% respectively after operation. Eleven patients showed less negative maximum inspiratory mouth pressures at any given lung volume after surgery and the magnitude of the change correlated with the reduction in total lung capacity. In 11 of the 12 patients the conduction times of the right and left phrenic nerves did not change substantially after operation and the ratio of inspiratory electrical activity (Edi) of left and right hemidiaphragms was similar before and after the procedure. One patient, however, showed a considerable increase in left phrenic nerve conduction time and a reduction in the left to right Edi ratio postoperatively. In three patients diaphragm function was also assessed by changes in transdiaphragmatic pressure during supramaximal phrenic nerve stimulation and voluntary increase in inspired volume; in none of the three patients did the transdiaphragmatic pressure swings show any significant change in the postoperative period. These data indicate that phrenic nerve paralysis only occasionally accounts for the postoperative loss of lung volume after coronary artery bypass grafting surgery. The mechanism of these abnormalities therefore remains to be determined.

Coronary Artery Bypass↗
PubMed1989

The effect of recipient lung size on lung physiology after heart-lung transplantation.

We studied the postoperative course of lung volumes in 32 heart-lung transplant recipients relative to the predicted total lung capacity of the individual donors, to assess the degree of inaccuracy likely to result from the radiological method of matching of donor and recipient lung sizes. There was a tendency for recipients with large preoperative lung volumes--from, for example, emphysema--to receive smaller lungs, while those with smaller volumes from pulmonary vascular disease received bigger donor lungs, but no immediate problems were incurred. After an initial fall in total lung capacity, the postoperative value of the total lung capacity approached the recipients' pretransplant value about one year after the operation irrespective of the size of the donor lungs. This suggests that chest wall compliance is the major determinant of postoperative lung volume and not the donor lung size or compliance. Exact matching of donors' and recipients' lung sizes may not be necessary, and if required can be simply achieved by comparing the measured total lung capacity in the recipient with the predicted value of the donor based on sex, age, and height.

Anthropometry↗
PubMed1994

Three-dimensional reconstruction of the in vivo human diaphragm shape at different lung volumes.

The ability of the diaphragm to generate pressures at different lung volumes (VLs) in humans may be determined by the following factors: 1) its in vivo three-dimensional shape, radius of curvature, and tension according to Laplace law; 2) the relative degree to which it is apposed to the rib cage (i.e., zone of apposition) and lungs (i.e., diaphragm dome); and 3) its length-force properties. To gain more insight into these factors we have reconstructed from nuclear magnetic images the three-dimensional shape of the diaphragm of four normal subjects under supine relaxed conditions at four different VLs: residual volume, functional residual capacity, functional residual capacity plus one-half of the inspiratory capacity, and total lung capacity. Under our experimental conditions the shape of the diaphragm changes substantially in the anteroposterior plane but not in the coronal one. Multivariate regression analysis indicates that the zone of apposition is dependent on both diaphragm shortening and lower rib cage widening with lung inflation, although much more on the first of these two factors. Because of the changes in anteroposterior shape and expansion of the insertional origin at the costal margin with lung inflation, the data therefore suggest that the diaphragm may be more accurately modeled by a "widening piston" (Petroll's model) than a simple "piston in a cylinder" model. A significant portion of the muscular surface is lung apposed, suggesting that diaphragmatic force has radial vectors in the dome and vectors along the body axis in the zone of apposition. The muscular surface area of the diaphragm decreased linearly by approximately 41% with VL from residual volume to total lung capacity. Diaphragmatic fibers may shorten under physiological conditions more than any other skeletal muscle. The large changes in fiber length combined with limited shape changes with lung inflation suggest that the length-twitch force properties of the diaphragm may be the most important factor for the pressure-generating function of this respiratory muscle in response to bilateral phrenic shocks at different VLs.

Diaphragm↗
PubMed1999

Airway flow limitation in patients with vibroacoustic disease.

INTRODUCTION: Vibroacoustic disease (VAD) is a pathology caused by occupational exposure to large pressure amplitude and low frequency (LPALF) noise (> or =90 dB SPL, < or =500 Hz), and has been the object of study by this group for the past 20 yr. In a group of 140 VAD-diagnosed patients, 7 non-smoker aircraft technicians developed clinical signs of respiratory insufficiency at an early age. Previously, multi-focal fibrosis had been observed in the lung of Wistar rats exposed to occupationally simulated LPALF noise and with no possibility of contamination by fumes, dust or other chemical agents. The goal of this study is to compare pulmonary imaging and/or functional changes in two age- and exposure-time matched groups of VAD-diagnosed aircraft technicians, with and without airflow limitation symptoms. METHODS: In a population of 140 individuals occupationally exposed to LPALF noise and diagnosed with VAD, we excluded the smokers (45 cases) and selected 7 individuals with complaints of airway flow limitations, average age 42.3 yr (SD = 2.3). From the remaining non-smokers without respiratory complaints, we selected a group of 15, age-matched patients (average age 36 yr, SD = 6.5). All subjects received a high-resolution CT scan of the chest and respiratory function tests consisting of body plethysmography, spirometry and metacholine airway provocation. RESULTS: There is a significant relationship between the presence of symptoms and imaging of lung fibrosis through high-resolution CT scan (p = 0.03624). There are no significant differences when both groups are compared with respect to the percentage of predicted values of lung function: Vital Capacity (VC), Total Lung Capacity, Forced Expiratory Volume during the first second of expiration, Maximal Expiratory Flow at 50% VC, Total Airway Resistance, and Airway Reactivity after 25 mg of metacholine. CONCLUSION: High resolution CT scan is a valuable tool for diagnosis of lung fibrosis in VAD patients who have symptoms of airway flow limitations. The fact that lung ventilation tests did not present significant changes between both groups is in agreement with findings in Wistar rats. This strongly suggests that a process of focal pulmonary fibrosis may be induced by occupational noise exposure, and is a feature of VAD.

Adult↗
PubMed1975

The N2 closing volume test in population studies: sources of variation and reproducibility.

Sources of variation in the nitrogen closing volume test and derived measurements were examined in the results of 13 subjects, each of whom performed 3 sequential trials on 2 occasions 30 to 60 minutes apart, on 2 separate days 1 week apart (156 trials in all). Results were examined to evaluate the relative sensitivity of the various measurements for differences between sujbects and, by implication, their potential value in population studies. Using the ratio of signal (between-subject variance) to noise (within-subject variance) as the criterion, the sensitivities of the ratio of closing volume to vital capacity (CV/VC,%) and the ratio of closing capacity to total lung capacity (CC/TLC,%) were comparable; contrary to expectation, sensitivity decreased rather than increased with side-by-side compared to independent tracing analysis. Comparison of various test schedules showed the greatest sensitivity when the mean of 3 measurements was used, with a single measurement of CV/VC,% being only one-third as sensitive, and a single measurement of CC/TLC,% being one-half as sensitive as the mean. In addition, the validity of the measurements of total lung capacity from nitrogen dilution in a single oxygen breath was confirmed by the demonstration of good agreement with helium dilution values.

Adult↗
PubMed2003

Contribution of airway closure to chronic postbronchiolitis airway dysfunction in rats.

Genetically susceptible Brown Norway rats develop a chronic asthmalike syndrome after recovering from viral bronchiolitis at an early age. We hypothesized that airway closure is an important mechanism of airflow obstruction in postbronchiolitis rats. Rats were studied 8-12 wk after inoculation with Sendai virus or sterile vehicle at 3-4 wk of age. Under light pentobarbital anesthesia, rats were instrumented with an orotracheal catheter and an esophageal pressure monitor and placed in a total body plethysmograph. Lung volumes and forced-expiratory maneuvers were measured using the Boyle's law method and software-controlled valving of positive and negative pressures to elicit lung inflations and rapid deflations; pulmonary resistance was measured during spontaneous tidal breathing; and quasi-static pressure-volume curves were obtained with passive inflations and deflations in fully anesthetized, paralyzed rats. Compared with controls, the postbronchiolitis rats had elevated pulmonary resistance and reduced forced-expiratory volume in 0.2 s. Most of the reduced forced-expiratory volume in 0.2 s was associated with reduced forced vital capacity, indicating premature airway closure as a prominent mechanism. The reduced airflow in postbronchiolitis rats was highly dependent on lung volume, being nearly normal at 70% lung capacity, but sevenfold less than normal at 30% lung capacity. Increased respiratory system hysteresis between functional reserve capacity and total lung capacity was evidence for increased airway closure at normal end-expiratory lung volumes in postbronchiolitis rats. We conclude that airway instability and closure is a prominent mechanism of the chronic airway dysfunction in rats that have recovered from viral bronchiolitis at an early age.

Airway Resistance↗
PubMed1983

Regional lung function in erect humans after lobectomy.

By using the 133Xe technique, we studied five erect adult subjects who had undergone lobectomy at least 2 mo previously and were otherwise normal, to allow comparison between operated and unoperated lungs; four subjects had undergone upper lobectomy, and one had undergone lower lobectomy. In addition we studied a sixth subject who had undergone lower lobectomy and had residual disease in the contralateral lung, and results from the diseased lung were discarded. At the same overall volume, lungs that had undergone lobectomy were more expanded than contralateral control lungs, and their washout half times were prolonged more than could be accounted for by their increased functional residual capacity-to-total lung capacity ratio. In subjects with upper lobectomy, apex-to-base gradients of regional lung volume were normal on the operated side when lung expansion was accounted for. In subjects with lower lobectomy, apex-to-base volume gradients were reduced on the side that had undergone resection, suggesting relative overexpansion of basal regions. These interpretations were supported by distributions of regional washout half times and of boluses inhaled at residual volume. We interpreted these results as indicating that both lung weight and lung-chest wall shape interaction determine the distribution of regional lung volumes.

Adolescent↗
PubMed1995

Effects of posture on respiratory mechanics in obesity.

Increased abdominal mass in obesity should enhance normal gravitational effects on supine respiratory mechanics. We have examined respiratory impedance (forced oscillation over 4-26 Hz applied at the mouth during tidal breathing), maximum inspiratory and expiratory mouth pressures (MIP and MEP), and maximum effort flow-volume curves seated and supine in seven obese subjects (O) (mean age 51 yr, body mass index 43.6 kg/m2) and seven control subjects (C) (mean age 50 yr, body mass index 21.8 kg/m2). Seated mean total lung capacity was smaller in O than in C (82 vs. 100% of predicted); ratio of functional residual capacity (FRC) to total lung capacity averaged 43% in O and 61% in C (P < 0.01). Total respiratory resistance (Rrs) at 6 Hz seated was higher in O (4.6 cmH2O.l-1.s) than in C (2.2 cmH2O.l-1.s; P < 0.001); total respiratory reactance (Xrs) at 6 Hz was lower in O than in C. In C, on changing to the supine posture, mean Rrs at 6 Hz rose to 2.9 cmH2O.l-1.s, FRC fell by 0.68 liter, and Xrs at 6 Hz showed a small fall. In O, despite no further fall in FRC, supine Rrs at 6 Hz increased to 7.3 cmH2O.l-1.s, and marked frequency dependency of Rrs and falls in Xrs developed. Seated, MIP and MEP in C and O were similar; supine there were small falls in MEP and maximum expiratory flow in O. The site and mechanism of the increase in supine Rrs and reduction in supine Xrs and the mechanism maintaining supine FRC in obesity all need further investigation.

Airway Resistance↗
PubMed1994

Pulmonary function and gastroesophageal reflux in systemic sclerosis.

OBJECTIVE: To determine the relations among esophageal dysfunction, gastroesophageal reflux, and lung involvement in patients with systemic sclerosis. DESIGN: Retrospective review of esophageal motility, esophageal pH, and pulmonary function data. SETTING: University hospital outpatient clinic and community. PATIENTS: 39 consecutively referred patients who were grouped according to the presence or absence of abnormal distal (pH < 4.0 for > 5% of the 24-hour monitoring period) or proximal (pH < 4.0 for > 1% of the 24-hour period) gastroesophageal acid reflux. Patients were also grouped according to the presence or absence of distal esophageal peristalsis. MEASUREMENTS: Esophageal manometry, dual-probe (distal and proximal) esophageal 24-hour pH measurements, and pulmonary function studies (forced vital capacity, forced expiratory volume at 1 second, total lung capacity, and single-breath carbon monoxide diffusing capacity [DLco]). RESULTS: The mean total lung capacity (values as percentage predicted) was 87.1% +/- 11.2% (SD) for patients with abnormal proximal reflux and 77.8% +/- 21.6% for patients with normal proximal reflux (difference, 9.3%; 95% CI, -1.4% to 20.0%). The mean forced vital capacity for these patients was 91.1% +/- 12.4% and 85.4% +/- 25.6%, respectively (difference, 5.7%; CI, -6.9% to 18.1%). The mean total lung capacity was 83.8% +/- 15.4% for patients with abnormal distal reflux and 77.9% +/- 22.7% for patients with normal distal reflux (difference, 5.9%; CI, -7.6% to 19.4%). Among potential confounders of pulmonary measures, only smoking was related to decreased pulmonary function (smoking related to decreased DLco P < 0.01). Smoking was more common in patients with abnormal distal reflux than in those with normal distal reflux (65% compared with 25%, P = 0.03). After adjusting for smoking, the difference in mean DLco between patients with abnormal compared with normal distal reflux was 7.19% (Cl, -8.5% to 22.9%). CONCLUSION: Important measures of lung volume indicative of interstitial lung disease (total lung capacity, forced vital capacity) do not appear to be related to abnormal gastroesophageal acid reflux in patients with systemic sclerosis.

Esophagus↗
PubMed1996

Long-term pulmonary toxicity of multiagent chemotherapy including bleomycin and cyclophosphamide in osteosarcoma survivors.

PURPOSE: To assess long-term pulmonary effects of multiagent chemotherapy, we studied serial pulmonary function tests (PFTs) of 35 children with osteosarcoma up to 12 years after diagnosis. PATIENTS AND METHODS: We analyzed 84 sets of PFTs from 35 patients diagnosed with osteosarcoma between 1981 and 1991. They received bleomycin, cyclophosphamide, methotrexate, doxorubicin, cisplatin, and actinomycin D over 9-12 months and we performed PFTs from 3 days to 152 months after diagnosis. Time period I included 36 PFTs (43%) performed between 1 and 5 months from diagnosis, time period II included 20 PFTs (24%) performed between 8 and 12 months from diagnosis, and time period III included 28 PFTs (33%) performed between 12 and 119 months from diagnosis. Total lung capacity (TLC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and carbon monoxide diffusing capacity (DLCO) were analyzed. Maximal respiratory pressures and arterial blood gases were measured to assess muscle weakness and gas exchange, respectively. Mean differences in PFTs were compared among the three time periods and between time period pairs. RESULTS: All mean PFT values showed significant differences among time periods. Significant decline in DLCO; (P=.012), TLC (P=.020), and FEV1 (P=.028) between time periods I and II were noted followed by a trend towards recovery between time periods II and III. Time periods I and III were not significantly different from one another. Mean PFTs performed after 2 years of diagnosis were not different from mean PFTs performed from diagnosis at 2 years. CONCLUSION: This dosage regimen of multi-agent chemotherapy for osteosarcoma patients caused a transient, but significant, decline in PFTs within 8-12 months after administration but appears to cause no significant long-term pulmonary function abnormalities.

Adolescent↗
PubMed1979

Obstruction of the respiratory pathways, its evaluation by methods of functional examination of the lungs and development in patients with cystic fibrosis.

In 28 patients with cystic fibrosis aged 5--24 years the values of maximum expiratory flow rates (Vmax) at lower volume levels were assessed, as well as the "specific" conductance of the respiratory pathways (Gaw/TGV), the vital capacity (VC), total lung capacity (TLC), residual volume (RV), functional residual capacity (FRC), RV/TLC and FRC/TLC ratios and the one-second forced expiration of the vital capacity (FEV1) to evaluate obstruction of the respiratory pathways. Most markedly and most frequently abnormal were the values of Vmax, RV and of the RV/TLC ratio. These findings revealed that in almost all patients with CF there was already during the initial examination an obstruction of the peripheral respiratory pathways and hyperinflation of the lungs. During repeated measurement of the above values of lung function in 15 patients with cystic fibrosis during a period of 1--5 years when the patients increased in height by 10 cm on average, the above values did not deteriorate on average. There was, however, an individual variability of the investigated values during this period. The comprehensive treatment provided in our country prevented in patients with CF a deterioration of obstruction of the respiratory pathways during the period of investigation.

Adolescent↗