Dynamic characteristics of the external respiratory function in young male residents of the north during the annual cycle

The following aspects were studied during the annual cycle in young men (aged 19.0 ± 0.9 years) living in northern European Russia (62°N): the peak and instantaneous volumetric flow rates (PVFR and IVFR, respectively) at the moments of expiration of 25, 50, and 75% of the forced vital capacity of the lungs (FVC); the average volumetric expiratory flow rate in the process of expiration from 25 to 75% of FVC; the respiratory rate; and the time of attainment of PVFR and FVC. The pulmonary function parameters were determined using an SPM-01-R-D microprocessor spirograph. It was found that only the velocity characteristics of the external respiratory function significantly (the F test) changed in young men during the annual cycle; the time functions were not significantly different. A greater variation in the velocity parameters of the external respiratory function was found during the annual cycle compared to those for the inhabitants of temperate latitudes, which is indicative of adaptive reactions of the external respiratory function and a slightly restricted bronchial patency at the level of mediumand, especially, small-caliber bronchi. The PVFR and IVFR at the moments of expiration of 25, 50, and 75% of FVC and the average volumetric expiratory flow rate in the 25–75% range of the FVC in the male residents of the North are higher during the cold season and lower in the warm season.     

Effects of rapid saline infusion on lung mechanics and airway responsiveness in humans.

Lung mechanics and airway responsiveness to methacholine (MCh) were studied in seven volunteers before and after a 20-min intravenous infusion of saline. Data were compared with those of a time point-matched control study. The following parameters were measured: 1-s forced expiratory volume, forced vital capacity, flows at 40% of control forced vital capacity on maximal (Vm(40)) and partial (Vp(40)) forced expiratory maneuvers, lung volumes, lung elastic recoil, lung resistance (Rl), dynamic elastance (Edyn), and within-breath resistance of respiratory system (Rrs). Rl and Edyn were measured during tidal breathing before and for 2 min after a deep inhalation and also at different lung volumes above and below functional residual capacity. Rrs was measured at functional residual capacity and at total lung capacity. Before MCh, saline infusion caused significant decrements of forced expiratory volume in 1 s, Vm(40), and Vp(40), but insignificantly affected lung volumes, elastic recoil, Rl, Edyn, and Rrs at any lung volume. Furthermore, saline infusion was associated with an increased response to MCh, which was not associated with significant changes in the ratio of Vm(40) to Vp(40). In conclusion, mild airflow obstruction and enhanced airway responsiveness were observed after saline, but this was not apparently due to altered elastic properties of the lung or inability of the airways to dilate with deep inhalation. It is speculated that it was likely the result of airway wall edema encroaching on the bronchial lumen.     

Acoustic and spirometry parameters of forced expiratory sounds during a five-day dry immersion

The dynamic studies of the parameters of forced expiration under the conditions of a five-day dry immersion involved seven healthy male subjects aged 20 to 25 years. During forced expiration, spirometry tests were performed simultaneously with tracheal sounds being recorded by a microphone. A number of parameters, including the acoustic duration of the forced-expiration tracheal sounds, the lungs’ forced vital capacity, the 1-s forced expiration volume, the peak expiratory flow, and time of achieving the peak expiratory flow, were recorded before dry immersion, on days 1 and 4 of immersion, and the next day after the termination of immersion. There was a significant decrease (by 8.4%) in the peak expiratory flow on day 1 of immersion; however, by day 4 of immersion, the peak expiratory flow increased by 8.9%, reaching its baseline values. The lungs’ forced vital capacity and the forced expiration volume during 1 second, on the average, did not change throughout the experiment. There was a significant increase (by 17%) in the duration of the forced expiration tracheal sounds after the immersion, which suggests an increase in respiratory resistance and needs further studies. A moderate negative correlation between the duration of the forced expiration tracheal sounds and Gensler’s index (r = ?0.63) was found, whereas the correlation with other spirometry parameters was weak or absent.     

Pulmonary and ventilatory responses to pregnancy, immersion, and exercise

To examine the effects of pregnancy, immersion, and exercise during immersion on pulmonary function and ventilation, 12 women were studied at 15, 25, and 35 wk of pregnancy and 8-10 wk postpartum. Pulmonary function and ventilation were measured under three experimental conditions: after 20 min of rest on land (LR), after 20 min of rest during immersion to the level of the xiphoid (IR), and after 20 min of exercise during immersion at 60% of predicted maximal capacity (IE). Forced vital capacity remained relatively constant, except for a decrease at 15 wk, for the duration of pregnancy. Expiratory reserve volume decreased with a change in the pregnancy status and with the duration of pregnancy. However, the forced vital capacity was maintained by an increase in the inspiratory capacity during pregnancy. Forced expiratory volume for 1 s, expressed as percent of forced vital capacity, did not differ significantly between conditions or as a result of pregnancy. Forced vital capacity was lower during the IR trial compared with LR and IE trials. The decreased forced vital capacity of the IR trials was mediated by a decrease in the expiratory reserve volume. Whereas the inspiratory capacity increased during IR and IE compared with LR, the increase was not large enough to offset the decrease in the expiratory reserve volume. Resting immersion resulted in a significant decrease in maximal voluntary ventilation as did pregnancy. Pregnancy resulted in significant increases in minute ventilation (VE), which were related to increases in the O2 consumption.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gravity effects on regional lung ventilation determined by functional EIT during parabolic flights.

Gravity-dependent changes of regional lung function were studied during normogravity, hypergravity, and microgravity induced by parabolic flights. Seven healthy subjects were followed in the right lateral and supine postures during tidal breathing, forced vital capacity, and slow expiratory vital capacity maneuvers. Regional 1) lung ventilation, 2) lung volumes, and 3) lung emptying behavior were studied in a transverse thoracic plane by functional electrical impedance tomography (EIT). The results showed gravity-dependent changes of regional lung ventilation parameters. A significant effect of gravity on regional functional residual capacity with a rapid lung volume redistribution during the gravity transition phases was established. The most homogeneous functional residual capacity distribution was found at microgravity. During vital capacity and forced vital capacity in the right lateral posture, the decrease in lung volume on expiration was larger in the right lung region at all gravity phases. During tidal breathing, the differences in ventilation magnitudes between the right and left lung regions were not significant in either posture or gravity phase. A significant nonlinearity of lung emptying was determined at normogravity and hypergravity. The pattern of lung emptying was homogeneous during microgravity.     

Changes in regional emptying sequence need not change maximum expiratory flow

Nine normal young men inhaled boluses of He at the onset of slow vital capacity (VC) inspirations. During the subsequent VC expirations, we measured expired flow, volume, and He concentrations. Expirations consisted of full or partial maximum expiratory flow-volume (MEFV) maneuvers. Full maneuvers were forced expirations from total lung capacity (TLC). Partial maneuvers were accomplished by expiring slowly from TLC to 70, 60, 50, and 40% VC and then initiating forced expiration. Expired He concentrations from full and partial maneuvers were compared with each other and with those resulting from slow expirations. At comparable volumes less than 50% VC, flow during partial and full MEFV maneuvers did not differ. Expired He concentrations were higher during partial maneuvers than during full ones; at the onset of partial maneuvers upper zone emptying predominated, whereas this was not the case at the same lung volumes during maneuvers initiated at TLC. We observed substantial differences in regional emptying sequence that did not influence maximum expiratory flow.     

Pulmonary function in young and older athletes and untrained men

This study compared the lung volumes and pulmonary functions of older endurance-trained athletes with those of healthy sedentary age-matched controls, young athletes, and young untrained men to determine whether training affects the age-associated changes in these variables. Despite large differences in maximal 02 consumption (VO2max), the older athletes and their sedentary peers had similar values for all pulmonary variables when expressed as absolute values. However, because the older athletes were shorter than the older sedentary men, their vital capacity, total lung capacity (TLC), and forced expiratory volume in 1 s were significantly larger than those of the older sedentary men when normalized for age and height; the average values for maximal voluntary ventilation and residual volume (RV) were also larger in the older athletes when normalized for age and height, but the differences were not significant. The young trained and untrained men did not differ in any of these measures. TLC was the only pulmonary variable that was the same in the young and older men; RV and the RV-to-TLC ratio were larger, whereas all other pulmonary function and volume measures were lower in the older men compared with the younger men. The older athletes were the only group whose lung volumes and pulmonary function measures were all, except for RV, substantially greater than expected based on their age and height. Thus prolonged strenuous endurance training in these older highly trained endurance athletes appears to have altered the decline in pulmonary function and volumes associated with aging.     

Lung mechanics in individuals with spinal cord injury: effects of injury level and posture.

Individuals with spinal cord injury (SCI) exhibit reduced lung volumes and flow rates as a result of respiratory muscle weakness. These features have not, however, been investigated in relation to the combined effects of injury level and posture. Changes in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV(1)), FEV(1)/FVC, forced expiratory flow at 50% vital capacity (FEF(50)), inspiratory capacity (IC), and expiratory reserve volume (ERV) were assessed by injury level in the seated and supine positions in 74 individuals with SCI. The main findings were 1) FVC, FEV(1), and IC increased with descending SCI level down to T(10), below which they tended to level off; 2) supine values of FVC and FEV(1) tended to be larger in the supine compared with the seated posture down to injury level T(1), caudad to which they were less than when seated; 3) IC increased proportionately more down to injury level L(1), below which it declined slightly and plateaued; 4) ERV was measurable even at high cervical injuries, was generally smaller in the supine position, reached peak values in both positions at T(10) injury level, and then rapidly declined at lower levels; 5) when subjects were separated according to current, former, and never smokers, only formerly smoking paraplegic individuals demonstrated spirometric values significantly less than paraplegic individuals who never smoked. Changes in spirometric measurements in SCI are dependent on injury level and posture. These findings support the concept that the increase in vital capacity in supine position is related to the effect of gravity on abdominal contents and increase in IC.     

Exercise flow-volume loops in prepubescent aerobically trained children.

We studied mechanical ventilatory constraints in 13 aerobically trained (Tr) and 11 untrained (UT) prepubescent children by plotting the exercise flow-volume (F-V) loops within the maximal F-V loop (MFVL) measured at rest. The MFVL allowed to determine forced vital capacity (FVC) and maximal expiratory flows. Expiratory and inspiratory reserve volumes relative to FVC (ERV/FVC and IRV/FVC, respectively) were measured during a progressive exercise test until exhaustion. Breathing reserve (BR) and expiratory flow limitation (expFL), expressed in percentage of tidal volume (V(T)) and defined as the part of the tidal breath meeting the boundary of the MFVL, were measured. Higher FVC and maximal expiratory flows were found in Tr than UT (P < 0.05) at rest. Our results have shown that during exercise, excepting one subject, all Tr regulated their V(T) within FVC similarly during exercise, by breathing at low lung volume at the beginning of exercise followed breathing at high lung volume at strenuous exercise. In UT, ERV/FVC and IRV/FVC were regulated during exercise in many ways. The proportion of children who presented an expFL was nearly the same in both groups (approximately 70% with a range of 14 to 65% of V(T)), and no significant difference was found during exercise concerning expFL. However, higher ventilation (V(E)), ERV/FVC, and dyspnea associated with lower BR, IRV/FVC, and SaO2 were reported at peak power in Tr than UT (P < 0.05). These results suggest that, because of their higher Ve level, trained children presented higher ventilatory constraints than untrained. These may influence negatively the SaO2 level and dyspnea during strenuous exercise.     

Biomechanics and regulation of external respiration under conditions of five-day dry immersion

The functional state of external respiration and the features of its regulation in healthy persons were studied under conditions of microgravity simulated using dry immersion. The lung volume, the ratio of thoracic and abdominal components during quiet breathing and performing various respiratory maneuvers, as well as the parameters that characterize the regulation of breathing (the duration of breath holding and the ability to voluntarily control respiratory movements), were recorded during the baseline period, on days 2 and 4 of dry immersion, and after the end of the dry immersion. It has been shown that the breathing pattern did not significantly change under conditions of dry immersion compared to the baseline period; however, the inspiratory reserve volume increased (p < 0.05), while the expiratory reserve volume decreased (p < 0.01). Dry immersion did not alter pulmonary ventilation, yet most of the subjects trended toward an increase in the contribution of the abdominal component of breathing movements during quiet breathing and demonstrated a statistically significant increase in this parameter during the lung vital capacity maneuver. The durations of the inspiratory and expiratory maximal breath holding under conditions of immersion did not differ from the background values. During the immersion, the accuracy of voluntary control of breathing increased. We believe that immersion, similar to microgravity, leads to changes in the reserve lung volume, which are partly because of changes in the body position; changes in relative contributions of the thoracic and abdominal components in the breathing movements; and changes in voluntary breath regulation.     

Model of forced expiratory flows and airway geometry in infants.

Early measurements of autopsied lungs from infants, children, and adults suggested that the ratio of peripheral to central airway resistance was higher in infants than older children and adults. Recent measurements of forced expiration suggest that infants have high flows relative to lung volume. We employed a computational model of forced expiratory flow along with physiological and anatomic data to evaluate whether the infant lung is a uniformly scaled-down version of the adult lung. First, we uniformly scaled an existing computational model of adult forced expiration to estimate forced expiratory flows (FEF) and density dependence for an 18-mo-old infant. The values obtained for FEF and density dependence were significantly lower than those reported for healthy 18-mo-old infants. Next, we modified the model for the infant lung to reproduce standard indexes of expiratory flow [forced expiratory volume in 0.5 s (FEV(0.5)), FEFs after exhalation of 50 and 75% forced vital capacity, FEF between 25 and 75% expired volume] for this age group. The airway sizes obtained for the infant lung model that produced accurate physiological measurements were similar to anatomic data available for this age and larger than those in the scaled model. Our findings indicate that the airways in the infant lung model differ from those in the scaled model, i.e., middle and peripheral airway sizes are larger than result from uniform downscaling of the adult lung model. We show that the infant lung model can be made to reproduce individual flow-volume curves by adjusting lumen area generation by generation.     

Dose response relation to oral theophylline in severe chronic obstructive airways disease.

OBJECTIVE--To evaluate measurement of the trapped gas volume as a measure of respiratory function in patients with chronic obstructive airways disease and their response to treatment with theophylline. DESIGN--Patients able to produce consistent results on testing of respiratory function spent two weeks having dosage of theophylline adjusted to give individual pharmacokinetic data. This was followed by random assignment to four consecutive two month treatment periods--placebo and low, medium, and high dose, as assessed by serum concentrations of theophylline. Respiratory function and exercise performance was assessed at the end of each two month period. SETTING--Chest unit in district hospital. PATIENTS--Thirty eight patients with chronic bronchitis and moderate to severe chronic obstruction to airflow were recruited; 33 aged 53-73 years completed the study. INTERVENTIONS--Dosage of oral theophylline increased during two week optimisation period to 800 mg daily unless toxicity was predicted, when 400 mg was given. Targets for the steady state serum theophylline concentrations were 5-10 mg/l in the low dose period, 10-15 mg/l in the medium dose, and 15-20 mg/l in the high dose period. ENDPOINTS--Respiratory function as measured by forced expiratory volume in one second, forced vital capacity, peak expiratory flow rate, slow vital capacity, and static lung volumes using helium dilution and body plethysmography from which trapped gas volume was derived. Exercise performance assessed by six minute walking test and diary cards using visual analogue scale. MEASUREMENTS AND MAIN RESULTS--The forced expiratory volume in one second, forced vital capacity, and peak expiratory flow rate changed only slightly (about 13%) over the range of doses. There was a linear dose dependent fall of trapped gas volume from 1.84 l (SE 0.157) to 1.42 l (0.152), 1.05 l (0.128), and 0.67 l (0.102) during the placebo and low, medium, and high dose treatment periods. Mean walking distance increased by up to 55.6 m (20%). There was a modest improvement in dyspnoea as the dose of theophylline was increased. Side effects were mostly minor but they became more frequent as the dose was increased. CONCLUSION--The fall in trapped gas volume may reflect an improvement in peripheral ventilation (associated with treatment with theophylline) which is less apparent in the more common tests of lung function used in patients with chronic obstructive airways disease.     

Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD.

During constant-work-rate exercise in chronic obstructive pulmonary disease, dyspnea increases steeply once inspiratory reserve volume (IRV) falls to a critical level that prevents further expansion of tidal volume (Vt). We studied the effects of this mechanical restriction on the quality and intensity of exertional dyspnea and examined the impact of an anticholinergic bronchodilator. In a randomized, double-blind, crossover study, 18 patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 s = 40 +/- 3%predicted; mean +/- SE) inhaled tiotropium 18 mug or placebo once daily for 7-10 days each. Pulmonary function tests and symptom-limited cycle exercise at 75% of each patient's maximal work capacity were performed 2 h after dosing. Dyspnea intensity (Borg scale), operating lung volumes, breathing pattern, and esophageal pressure (n = 11) were measured during exercise. Dynamic hyperinflation reached its maximal value early in exercise and was associated with only mild increases in dyspnea intensity and the effort-displacement ratio, which is defined as the ratio between tidal swings of esophageal pressure (expressed relative to maximum inspiratory pressure) and Vt (expressed relative to predicted vital capacity). After a minimal IRV of 0.5 +/- 0.1 liter was reached, both dyspnea and the effort-displacement ratio rose steeply until an intolerable level was reached. Tiotropium did not alter dyspnea-IRV relationships, but the increase in resting and exercise inspiratory capacity was associated with an improved effort-displacement ratio throughout exercise. Once a critically low IRV was reached during exercise, dyspnea rose with the disparity between respiratory effort and the Vt response. Changes in dyspnea intensity after tiotropium were positively correlated with changes in this index of neuromechanical coupling.     

Exercise-induced bronchodilation in natural and induced asthma: effects on ventilatory response and performance.

We studied whether bronchodilatation occurs with exercise during the late asthmatic reaction (LAR) to allergen (group 1, n = 13) or natural asthma (NA; group 2, n = 8) and whether this is sufficient to preserve maximum ventilation (VE(max)), oxygen consumption (VO(2 max)), and exercise performance (W(max)). In group 1, partial forced expiratory flow at 30% of resting forced vital capacity increased during exercise, both at control and LAR. W(max) was slightly reduced at LAR, whereas VE(max), tidal volume, breathing frequency, and VO(2 max) were preserved. Functional residual capacity and end-inspiratory lung volume were significantly larger at LAR than at control. In group 2, partial forced expiratory flow at 30% of resting forced vital capacity increased greatly with exercise during NA but did not attain control values after appropriate therapy. Compared with control, W(max) was slightly less during NA, whereas VO(2 max) and VE(max) were similar. Functional residual capacity, but not end-inspiratory lung volume at maximum load, was significantly greater than at control, whereas tidal volume decreased and breathing frequency increased. In conclusion, remarkable exercise bronchodilation occurs during either LAR or NA and allows VE(max) and VO(2 max) to be preserved with small changes in breathing pattern and a slight reduction in W(max).     

Short-term hypoxic exposure at rest and during exercise reduces lung water in healthy humans.

Hypoxia and hypoxic exercise increase pulmonary arterial pressure, cause pulmonary capillary recruitment, and may influence the ability of the lungs to regulate fluid. To examine the influence of hypoxia, alone and combined with exercise, on lung fluid balance, we studied 25 healthy subjects after 17-h exposure to 12.5% inspired oxygen (barometric pressure = 732 mmHg) and sequentially after exercise to exhaustion on a cycle ergometer with 12.5% inspired oxygen. We also studied subjects after a rapid saline infusion (30 ml/kg over 15 min) to demonstrate the sensitivity of our techniques to detect changes in lung water. Pulmonary capillary blood volume (Vc) and alveolar-capillary conductance (D(M)) were determined by measuring the diffusing capacity of the lungs for carbon monoxide and nitric oxide. Lung tissue volume and density were assessed using computed tomography. Lung water was estimated by subtracting measures of Vc from computed tomography lung tissue volume. Pulmonary function [forced vital capacity (FVC), forced expiratory volume after 1 s (FEV(1)), and forced expiratory flow at 50% of vital capacity (FEF(50))] was also assessed. Saline infusion caused an increase in Vc (42%), tissue volume (9%), and lung water (11%), and a decrease in D(M) (11%) and pulmonary function (FVC = -12 +/- 9%, FEV(1) = -17 +/- 10%, FEF(50) = -20 +/- 13%). Hypoxia and hypoxic exercise resulted in increases in Vc (43 +/- 19 and 51 +/- 16%), D(M) (7 +/- 4 and 19 +/- 6%), and pulmonary function (FVC = 9 +/- 6 and 4 +/- 3%, FEV(1) = 5 +/- 2 and 4 +/- 3%, FEF(50) = 4 +/- 2 and 12 +/- 5%) and decreases in lung density and lung water (-84 +/- 24 and -103 +/- 20 ml vs. baseline). These data suggest that 17 h of hypoxic exposure at rest or with exercise resulted in a decrease in lung water in healthy humans.     

Physiological characterization of variability in response to lung volume reduction surgery.

This paper examines potential physiological mechanisms responsible for improvement after lung volume reduction surgery (LVRS). In 25 patients (63 +/- 9 yr; 11 men, 14 women), spirometry [forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC)], lung volumes [residual volume (RV) and total lung capacity (TLC)], small airway resistance, recoil pressures, and respiratory muscle contractility (RMC) were measured before and 4-6 mo after LVRS. Data were interpreted to assess how changes in each component of lung mechanics affect overall function. Among responders (DeltaFEV(1) > or = 12%; 150 ml), improvement was primarily due to an increase in FVC, not to FEV(1)-to-FVC ratio. Among nonresponders, FEV(1), FVC, and RV/TLC did not change after surgery, although recoil pressure increased in both groups. Both groups experienced a reduction in RMC after LVRS. In conclusion, LVRS improves function in emphysema by resizing the lung relative to the chest wall by reducing RV. LVRS does not change airway resistance but decreases RMC, which attenuates the potential benefits of LVRS that are generated by reducing RV/TLC. Among nonresponders, recoil pressure increased out of proportion to reduced volume, such that no increase in vital capacity or improvement in FEV(1) occurred.     

Respiratory mechanics and maximal expiratory flow in the anesthetized mouse.

Mice have been widely used in immunologic and other research to study the influence of different diseases on the lungs. However, the respiratory mechanical properties of the mouse are not clear. This study extended the methodology of measuring respiratory mechanics of anesthetized rats and guinea pigs and applied it to the mouse. First, we performed static pressure-volume and maximal expiratory flow-volume curves in 10 anesthetized paralyzed C57BL/6 mice. Second, in 10 mice, we measured dynamic respiratory compliance, forced expiratory volume in 0.1 s, and maximal expiratory flow before and after methacholine challenge. Averaged total lung capacity and functional residual capacity were 1.05 +/- 0.04 and 0.25 +/- 0.01 ml, respectively, in 20 mice weighing 22.2 +/- 0.4 g. The chest wall was very compliant. In terms of vital capacity (VC) per second, maximal expiratory flow values were 13.5, 8.0, and 2.8 VC/s at 75, 50, and 25% VC, respectively. Maximal flow-static pressure curves were relatively linear up to pressure equal to 9 cm H(2)O. In addition, methacholine challenge caused significant decreases in respiratory compliance, forced expiratory volume in 0.1 s, and maximal expiratory flow, indicating marked airway constriction. We conclude that respiratory mechanical parameters of mice (after normalization with body weight) are similar to those of guinea pigs and rats and that forced expiratory maneuver is a useful technique to detect airway constriction in this species.     

The ventilatory responses of the caecilian Typhlonectes natans to hypoxia and hypercapnia

Typhlonectes natans empty their lungs in a single extended exhalation and subsequently fill their lungs by using a series of 10-20 inspiratory buccal oscillations. These animals always use this breathing pattern, which effectively separates inspiratory and expiratory airflows, unlike most urodele and anuran amphibians that may use one to many buccal oscillations for lung inflation and typically mix expired and inspired gases. Aquatic hypoxia had no significant effect on the breathing pattern or mechanics in these animals. Aerial hypoxia stimulated ventilatory frequency and increased the number of inspiratory oscillations but had little effect on inspiratory and expiratory tidal volume. Aquatic hypercapnia elicited a large significant increase in air-breathing frequency and minute ventilation compared to the small stimulation of minute ventilation seen during aerial hypercapnia. Some animals responded to aquatic hypercapnia with a series of three or four closely spaced breaths separated by long nonventilatory periods. Overall, T. natans showed little capacity to modulate expiratory or inspiratory tidal volumes and depended heavily on changing air-breathing frequency to meet hypoxic and hypercapnic challenges. These responses are different from those of anurans or urodeles studied to date, which modulate both the number of ventilatory oscillations in lung-inflation cycles and the degree of lung inflation when challenged with peripheral or central chemoreceptor stimulation.     

Pulmonary Function after Lymphography

The effects of lymphography on ventilatory function and gas transfer factor were studied in nine patients. Serial measurements made up to one month showed no change in the forced expiratory volume in one second or vital capacity. A small but reversible fall in transfer factor was found. The greatest reduction was at 24 or 48 hours. It was concluded that patients with normal lungs are unlikely to encounter difficulties but that patients with severe lung disease require careful assessment before lymphography.     

Ventilatory Tests and Pulmonary Conductance in Hospitalized Patients

In a series of 49 patients, including individuals with varying lung pathology and some older patients with no lung disease, the usual excellent correlation between first-second forced expiratory volume and maximum breathing capacity was found (coefficient of correlation=0.88). The first-second forced expiratory volume and maximum mid-expiratory flow rate were also seen to be closely related (coefficient of correlation=0.87). The relationship between these ventilatory tests and direct mechanical measurements of pulmonary resistance, however, was not as striking. Reduction in pulmonary compliance not due to loss or removal of pulmonary tissue did not affect the interrelationships between these tests. First-second forced expiratory volume, expressed as a percentage of the predicted vital capacity, was more closely related to the expression “% of predicted maximum breathing capacity” than the first-second forced expiratory volume, expressed as a percentage of the actual vital capacity (p<.05).