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Results for “Functional Residual Capacity”

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PubMed1994

Unspecific bronchial reactivity to carbachol in healthy subjects--effect of age and smoking habits.

Chronic inflammatory processes of the airways induced by long-time cigarette consumption are a crucial factor in the pathogenesis of chronic obstructive pulmonary disease. In contrast, the role of cigarette smoking in the pathogenesis of bronchial hyperreactivity (BHR) is still unclear. The aim of this study was to assess the effect of chronic cigarette consumption on pulmonary function tests and BHR in healthy subjects. 63 healthy smokers and 63 lifetime nonsmokers matched for sex, age, height and weight were evaluated. Pulmonary function was determined by body plethysmography and spirometry. Bronchial provocation was performed by inhalation of increasing doses of carbachol (up to 25 g/l) in isotonic NaCl solution. Pulmonary function tests were within normal limits in all subjects. Nevertheless, midexpiratory flow at 25% of forced vital capacity was significantly smaller, and functional residual capacity was significantly greater in middle-aged smokers (age: 40-60 years) compared to middle-aged nonsmokers (p < 0.05, both comparisons). In young smokers and nonsmokers (age: 20-30 years) pulmonary function tests were not different (p > 0.28, all comparisons). Importantly, the carbachol concentration that provoked a 50% rise in specific airway resistance (PD50sRaw) was similar in smokers and nonsmokers of both age groups (p > 0.05, both comparisons) and did not correlate with the age of the subjects (p > 0.2). No correlations between baseline values of pulmonary function tests and PD50sRaw were observed (p > 0.34, all comparisons). The observations confirm that the distribution profile of BHR is unimodal and apparently not affected by age and smoking habits.

Adult↗

PubMed1992

Mechanical implications of in vivo human diaphragm shape.

Using magnetic resonance imaging, we measured the three-dimensional form of the diaphragm in vivo in four supine relaxed subjects at functional residual capacity and calculated its total surface area, the right and left surface areas in the zone of apposition, and the principal radii of curvature as a function of height. The area of apposition comprised 45 +/- 1.5% (SE) of the total surface area of the diaphragm. Available data on the area of the central tendon indicate that a considerable part of the muscular part of the diaphragm is lung apposed. The curvature was linearly related to height over 7 cm of the posterior half of each hemidiaphragm. From the linear portion of this graph and assuming a vertical gradient of transdiaphragmatic pressure of 0.75 cmH2O/cm, we applied the Laplace law and calculated tensions of 54 and 32 g/cm for right and left sides, respectively. We conclude that the shape of at least part of the posterior half of the relaxed human diaphragm in the supine position at functional residual capacity can be explained by the Laplace law, suggesting that both the lung and abdominal contents behave sufficiently as fluids so that they do not impose their shape on the diaphragm. Because diaphragm muscle is partly lung apposed, it is unlikely that the diaphragm functions simply as a piston.

Adult↗

PubMedDate not supplied

Imaging diagnosis: acute lung injury following massive bee envenomation in a dog.

A 5-year-old neutered male mixed breed dog presented for increased respiratory effort after being stung by over 100 bees and developing anaphylactic shock. Given the history, clinical signs and thoracic radiographic findings of a mild bilateral interstitial pattern, acute lung injury/acute respiratory distress syndrome (ALI/ARDS) was suspected. Further testing was performed to support this diagnosis. On computed tomographic images, there was a diffuse bilateral opacification of the lungs, with preservation of bronchial and vascular margins. Pulmonary function testing indicated decreased pulmonary compliance, decreased diffusion capacity and decreased functional residual capacity. These results supported the diagnosis of ALI/ARDS secondary to bee sting envenomation and development of anaphylactic shock. After 8 days of treatment with oxygen, steroids, antibiotics, and bronchodilators the dog improved. This case demonstrates the usefulness of computed tomography and pulmonary function testing in the diagnosis of ALI/ARDS.

Anaphylaxis↗

PubMed1978

Effects of sulfuric acid aerosol on cardiopulmonary function of dogs, sheep, and humans.

Submicronic aerosol of sulfuric acid (H2SO4) originates from the burning of fossil fuels and discharge of vapor from the automobile engine equipped with the catalytic converter. This study was conducted to determine whether brief exposure to this aerosol in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs that breathed H2SO4 aerosol in concentrations up to 8 mg per m3 showed no effects on respiratory resistance, static lung compliance, and functional residual capacity. A 4-hour exposure to H2SO4 aerosol (4 mg per m3) produced no significant changes in mechanics of breathing, functional residual capacity, pulmonary and systemic arterial blood pressures, cardiac output, heart rate, and arterial blood gas tensions. Conscious sheep that breathed H2SO4 aerosol in concentrations up to 14 mg per m3 for 20 min had no alteration of tracheal mucous velocity in an immediate 3-hour follow-up period or 5 to 10 days later. Conscious sheep that breathed H2SO4 aerosol (4 mg per m3) for 4 hours had no significant alteration of tracheal mucous velocity immediately and 2 hours thereafter. Both normal and asthmatic adults breathing H2SO4 aerosol in concentrations up to 1 mg per m3 for 10 min showed no significant alteration of lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, oscillation mechanics of the chest-lung system, pulmonary capillary blood flow, diffusing capacity, O2 consumption, and pulmonary tissue volume. No delayed effects in pulmonary function nor exacerbation of bronchial asthma were observe during a follow-up period of a few weeks. The present study indicates that single exposure to submicronic H2SO4 aerosol does not produce an immediate or a delayed adverse effect on cardiopulmonary function in anesthetized dogs, conscious sheep, and normal and asthmatic adults.

Aerosols↗

PubMed2003

[Expression of matrix metalloproteinases in lung tissue and levels of some cytokines in bronchoalveolar lavage fluid in the obstructive emphysema rat models].

OBJECTIVE: To observe the changes of matrix metalloproteinase-2 (MMP-2), MMP-9 and interleukin-10 (IL-10), tumor necrosis factor-alpha (TNFalpha) in lung tissue of the obstructive emphysema rat models and to evaluate the relationship between these changes and emphysema formation. METHODS: The rat emphysema models were established by exposure to cigarette smoking. Pulmonary function tests were performed to evaluate the forced expiratory volume in 0.3 second (FEV(0.3)), FEV(0.3)/forced vital capacity (FVC) and functional residual capacity (FRC). The morphological indices of emphysema were measured by computer image analyzer. The protein expression and enzymatic activity of MMPs in lung tissue were observed. The contents of IL-10 and TNFalpha in bronchoalveolar lavage fluid (BALF) were measured. RESULTS: Pulmonary function test showed that in model group the FEV(0.3)/FVC was decreased, whereas the FRC was increased significantly than those in control group (P < 0.01, respectively). There was a significant decrease in the relative content of elastin in lung tissue in model group than that in control group. The expression and enzymatic activity of MMP-2 and MMP-9 in lung tissue, the counts of total leukocytes and neutrophils and the level of TNFalpha in BALF were significantly elevated, but the level of IL-10 in BALF was significantly reduced in model group compared with those in control group (P < 0.01, respectively). There were statistically significant positive correlations between the enzymatic activity of MMP-2, MMP-9 and the total leukocyte counts (P < 0.01, respectively), and significant negative correlations between the enzymatic activity of MMP-2, MMP-9 and the content of elastin (P < 0.05, respectively). CONCLUSIONS: MMP-2, MMP-9, IL-10 and TNFalpha may play an important role in the formation of obstructive emphysema in rat models caused by passive smoking.

Animals↗

PubMed1998

Pathophysiology of changes in absolute lung volumes.

Changes in absolute lung volumes are common in lung disease and result in significant impacts on gas exchange, respiratory muscle function, the sensation of dyspnoea, and limitations to maximal exercise. Though our knowledge regarding the magnitude and determinants of changes in lung volumes in health and disease has increased in the past 20 years, a number of important questions remain unanswered. Consideration of the limitations of specific methods for measuring lung volumes is essential when analysing published studies regarding absolute lung volumes in infants, children and adults. Though functional residual capacity is most commonly measured in children and adults with the subject awake and at rest, increasingly attention is being directed to making these measurements under clinically more relevant conditions (e.g. during exercise, sleep, anesthesia, or mechanical ventilation). The relationships between dynamic changes in functional residual capacity, flow limitation during tidal breaths, sensation of dyspnoea and exercise limitation are important to understand, and are the focus of current and future research. Improved understanding of these relationships may lead to improvements in therapy of patients with acute and chronic lung disease and are likely to be particularly important for evaluating the efficacy of and optimal patient selection for new modes of therapy, such as lung volume reduction surgery.

Adolescent↗

PubMed1986

[Evaluation of the efficacy of the surgical treatment of panlobular emphysema].

26 patients presenting with panlobular emphysema between 1978 and 1984 were submitted to a thoracotomy for surgical resection of their bullae. Pre-operative and post-operative evaluations of the following were made: The level of dyspnoea in 5 grades. The FEV1 (VEMS) the forced vital capacity (CVF) the functional residual capacity (CRF) measured plethysmographically, the residual volume (VR), the total lung capacity (CPT). Arterial blood gases. The presence of radiological signs of compression on pulmonary angiography and on plain chest radiographs: an index of compression rated 0 to 6 was defined at the outset. The subjects were split into 3 groups based on their post-operative respiratory function: Group 1: no improvement (n = 7). Group 2: moderate improvement of dyspnoea (n = 11). Group 3: a big improvement in dyspnoea (n = 7). These three groups were homogenous as regards their preoperative respiratory function. On the other hand, the compression caused by the bullae based on the pre-operative radiological data was much greater (p 0.01) in the group of patients who improved. In addition when the index of compression was equal or superior to 3 (n = 14) all the patients were improved (n = 6). The comparison of pre- and post-operative values shows the following results: The change in blood gases was very limited in all groups; the ventilatory parameters were unchanged in group 1; on the other hand in group 2 and 3 one notes an overall improvement in pulmonary function. The size of the improvement however, was very variable from one individual to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1985

Developmental alterations in pulmonary function of the lamb.

Pulmonary function was evaluated in 40 lambs ranging in age from 106 to 161 postconceptual days. Preterm lambs were delivered by cesarean section and newborn lambs were delivered vaginally. All animals were mechanically ventilated and had indwelling catheters. Measurements of transpulmonary pressure, airflow, tidal volume and functional residual capacity enabled calculations of lung compliance, specific compliance, lung conductance and specific conductance. Regression analysis indicated that lung compliance, lung conductance and functional residual capacity increased with developmental age; whereas, specific compliance and specific conductance decreased with maturity. These data quantitate the developmental alterations in the pulmonary function of preterm, term and newborn lambs.

Aging↗

PubMed2004

Assessment of the development of choked flow during total liquid ventilation.

OBJECTIVE: The flow rate of a liquid drainage from the lungs is limited because of the elastic nature of the airways. This study was designed to clarify the relationship between intrapulmonary liquid volume and the development of the flow limitation or choked flow phenomenon as a function of expiratory flow rate during total liquid ventilation with perflubron. DESIGN: Prospective animal study. SETTING: University research laboratory. SUBJECTS: Rabbits with a weight of 3.2 +/- 0.3 kg. INTERVENTIONS: After the rabbits were killed, the lungs were filled to functional residual capacity with perflubron, followed by administration of an additional volume of 30, 45, or 60 mL of perflubron (initial volume = functional residual capacity + additional volume). MEASUREMENTS AND RESULTS: In one set of five animals, the intratracheal pressure at the occurrence of choked flow was established at -20 mm Hg. In another set of six animals, we demonstrated that the volume remaining in the lung at the point of development of choked flow (Vch) was stable for the first 40 mins after the animals were killed. Flow rates of 1.25, 2.5, 3.75, 5.0, 7.5, 10.0, and 12.5 mL/sec were then applied at an additional volume of 30, 45, or 60 mL to 34 animals. Vch approximately doubled as the flow rate increased from 1.25 mL/sec to 12.5 mL/sec (p <.001). At the same flow, Vch was higher for an additional volume of 60 mL than 30 mL when the flow was > or =2.5 mL/sec. CONCLUSIONS: From these data, we conclude that choked flow occurs at intratracheal pressure of less than -20 mm Hg, that Vch is stable for the first 40 mins after the animals are killed, and that Vch is a function of flow rate and initial volume.

Airway Obstruction↗

PubMed1997

Lung hyperinflation and flow limitation in chronic airway obstruction.

We reasoned that if flow limitation plays an important role in lung hyperinflation, then bronchodilatation should be associated with a decrease of functional residual capacity (FRC) only in subjects breathing under conditions of flow limitation. This hypothesis was tested in 33 subjects with chronic airway narrowing due to asthma or chronic obstructive pulmonary disease (COPD). Flow limitation during tidal breathing was inferred from the impingement of the tidal flow-volume loop on the flow recorded during submaximally forced expiratory manoeuvres initiated from end-tidal inspiration. At baseline, flow limitation during tidal breathing was present in seven asthmatic (Group 1) and eight COPD subjects (Group 2), but absent in 11 asthmatic (Group 3) and seven COPD subjects (Group 4). FRC (mean+/-SEM) was similar in the four groups (range 117+/-7 to 134+/-6% of predicted). Inhalation of salbutamol (200 microg) caused significant increments of the forced expiratory volume in one second (FEVI) (range 6+/-1 to 21+/-8% of baseline) and forced expiratory flows at 30% of baseline forced vital capacity (V'30) (range 58+/-13 to 235+/-93% of baseline) in all groups. In groups with flow limitation during tidal breathing at baseline the FRC measured by plethysmography decreased significantly (12+/-2% in Group 1, and 9+/-2% in Group 2), and the inspiratory capacity (IC) measured by spirometry increased significantly (17+/-3% in Group 1 and 7+/-3% in Group 2). This was associated with flow limitation disappearing at the volume of baseline end-tidal expiration. In Groups 3 and 4 neither FRC nor IC changed significantly. The breathing pattern was not modified in any group after salbutamol. These findings suggest that flow limitation may contribute to generation of lung hyperinflation both in asthma and chronic obstructive pulmonary disease. We speculate that the increment of functional residual capacity could be triggered by dynamic airway compression downstream from the flow-limiting segment.

Adult↗

PubMed1997

[Associations between breathing pattern during submaximal exercise and exercise capacity in patients with pulmonary emphysema].

We sought to clarify the factors associated with exercise capacity in patients with pulmonary emphysema. Exercise capacities of 20 men with pulmonary emphysema were evaluated by bicycle ergometery, and the results were used to divide the subjects into two groups: high exercise capacity (n = 10) and low exercise capacity (n = 10). Pulmonary-function tests were done, emphysema scores were computed from CT scans, breathing pattern was recorded during submaximal exercise (up to 20 watts), and index of rapid shallow breathing was computed. Neither FEV1 nor airway resistance differed between the two groups, and patients with lower exercise capacity tended to have lower tidal volumes and higher values of the index of rapid shallow breathing during submaximal exercise. Functional residual capacity measured by body plethysmography and emphysema scores were inversely associated with exercise capacity. We speculate that among patients with pulmonary emphysema and a given degree of airway obstruction, a high functional residual capacity causes breathing during submaxinal exercise to be rapid and shallow, and that this rapid and shallow breathing makes ventilation inefficient, increases the work of breathing, and limits exercise capacity.

Aged↗

PubMed2005

The effect of lung inflation on the inspiratory action of the canine parasternal intercostals.

Inflation induces a marked decrease in the lung-expanding ability of the diaphragm, but its effect on the parasternal intercostal muscles is uncertain. To assess this effect, the phrenic nerves and the external intercostals were severed in anesthetized, vagotomized dogs, such that the parasternal intercostals were the only muscles active during inspiration, and the endotracheal tube was occluded at different lung volumes. Although the inspiratory electromyographic activity recorded from the muscles was constant, the change in airway opening pressure decreased with inflation from -7.2+/-0.6 cmH2O at functional residual capacity to -2.2+/-0.2 cmH2O at 20-cmH2O transrespiratory pressure (P<0.001). The inspiratory cranial displacement of the ribs remained virtually unchanged, and the inspiratory caudal displacement of the sternum decreased moderately. However, the inspiratory outward rib displacement decreased markedly and continuously; at 20 cmH2O, this displacement was only 23+/-2% of the value at functional residual capacity. Calculations based on this alteration yielded substantial decreases in the change in airway opening pressure. It is concluded that, in the dog, 1) inflation affects adversely the lung-expanding actions of both the parasternal intercostals and the diaphragm; and 2) the adverse effect of inflation on the parasternal intercostals is primarily related to the alteration in the kinematics of the ribs. As a corollary, it is likely that hyperinflation also has a negative impact on the parasternal intercostals in patients with chronic obstructive pulmonary disease.

Animals↗

PubMed1983

Improvement in pulmonary function in patients having combined anterior and posterior spine fusion for myelomeningocele scoliosis.

Thirteen patients with myelomeningocele scoliosis whose surgery necessitated anterior exposure of the thoracic spine were tested for changes in pulmonary function following spinal stabilization. The majority of patients exhibited a T12 level paralysis and a mean scoliosis of 72 degrees. Average correction of scoliosis for the series was 63%, and two cases with one level pseudarthrosis had no loss of correction. Ten of 13 patients were tested for pulmonary function one month prior to surgery and an average of ten months postoperatively. Eight of the ten patients demonstrated increase in peak flow postoperatively. Five demonstrated increase in maximum voluntary ventilation, and six cases showed increased functional residual capacity. Forced vital capacity increased in two, decreased in five, and showed no change in three patients. Improvement in peak flow, maximum voluntary ventilation, and functional residual capacity was noted in all five cases with scoliotic deformity in excess of 60 degrees (mean 93 degrees). It is postulated that, following spinal stabilization, these patients are able to improve their thoracic mechanics, enhancing greater expiratory flow with greater endurance.

Adolescent↗

PubMed1991

Effect of increased acceleration on regional pleural pressure in dogs.

The variation of pleural pressure was measured in anesthetized spontaneously breathing dogs subjected to increased acceleration (0-4 G) in a centrifuge. Two groups of animals were studied. In one group, the resultant acceleration was in a direction either ventral-to-dorsal (+Gx) or dorsal-to-ventral (-Gx), with a relatively small residual cranial-to-caudal acceleration. In the other group, the resultant acceleration was either cranial-to-caudal (+Gz) or caudal-to-cranial (-Gz), with a relatively small residual dorsal-to-ventral acceleration. Pleural liquid pressure (Ppl) was measured by two rib capsules that were separated by 7-9 cm and oriented either in the dorsal-to-ventral or cranial-to-caudal direction. At functional residual capacity, Ppl in the nondependent lung region became more negative when the acceleration was in the +Gx or +Gz direction. Thus the lung would be susceptible to damage that results from overexpansion in these acceleration directions. By contrast, acceleration in the -Gx or -Gz direction produced values of Ppl at functional residual capacity that were positive. Thus, in these acceleration directions, the respiratory muscles must provide greater force during inspiration to overcome lung compression before lung ventilation can occur. The Ppl gradients with respect to the acceleration directions increased approximately in proportion to acceleration in the +Gx, -Gx, and -Gz directions but remained relatively constant in the +Gz direction.

Acceleration↗

PubMed1991

[The ventilatory response to CO2 during end-expiratory negative extra-thoracic pressure and PEEP].

The effects of end-expiratory negative extra-thoracic pressure (EENETP) and PEEP on the ventilatory response to CO2 were studied in seven healthy volunteers. The changes in functional residual capacity during EENETP -20 cmH2O and PEEP 5 cmH2O were 13.9 and 12.9 ml.kg-1, respectively. The slopes of CO2 response (minute ventilation/end-tidal CO2) during ZEEP, EENETP and PEEP were 0.913, 0.622, 0.693 l.min-1.mmHg-1, respectively. The slopes during EENETP and PEEP were significantly decreased. These results indicate that EENETP and PEEP could worsen the CO2 response in patients with respiratory failure, especially, with chronic obstructive pulmonary disease in which functional residual capacity is increased.

Adult↗

PubMed1985

Halothane anesthesia reduces pulmonary function in the newborn lamb.

To study the effects of anesthesia on respiratory function of the neonate, the authors investigated the effect of breathing 100% oxygen and of breathing oxygen plus 0.75 MAC halothane on functional residual capacity, lung and airway resistance, expired minute volume, work of breathing, lung compliance, and blood gases and pH in nine 5-8-day-old, 4.6-7.7-kg lambs. Breathing 100% oxygen increased PaO2 but had no effect on PaCO2, minute ventilation, or lung mechanics. Three-fourths MAC halothane depressed minute ventilation 34% +/- 13% (P less than 0.05) and increased PaCO2 50% +/- 5% (P less than 0.05). Lung and airway resistance increased 59% +/- 26% (P less than 0.05); work of breathing decreased (P less than 0.05); and lung compliance was unchanged. Functional residual capacity was reduced 32% +/- 6% (P less than 0.05), which may be due to loss of diaphragm and intercostal muscle function and to an inability to take deep breaths. The authors conclude that 0.75 MAC halothane significantly impairs the pulmonary function of lambs who breathe spontaneously. Similar changes in human infants could account for the hypoxemia and hypercarbia that often are seen during anesthesia.

Airway Resistance↗

PubMed2003

Pulmonary gas trapping increases in asthmatic children and adolescents in the supine position.

This study aimed to see if gas trapping or ventilation inhomogeneity during tidal breathing increases in young asthmatic subjects when recumbent over a period of 1 hr. Ten asthmatic children and teenagers and 12 control subjects performed tidal breathing multiple-breath N(2)-washout in the sitting position and immediately, 30 min, and 60 min after assuming the supine position. The asthma group also performed the same lung function tests on another day, but then remained in the sitting position throughout. When assuming the supine position, both groups showed significant falls in vital capacity (4-8%) and in functional residual capacity (FRC) (>20%). Gas trapping increased significantly after 30 and 60 min in the supine position only in the asthma group, but other indices of ventilation inhomogeneity did not change with body position. When in the supine position, the trapped gas volume was on average 10% of FRC in the asthma group, which was twice as much as when sitting and three times higher than in supine control subjects. It is concluded that assuming the supine position leads to increased gas trapping in young asthmatics but not in healthy subjects; this could be one of several mechanisms that contribute to nocturnal worsening of asthma.

Age Distribution↗

PubMed2002

Effect of methotrexate on pulmonary function in patients with rheumatoid arthritis--a prospective study.

If given in high doses, methotrexate (MTX), a folate antagonist, could cause pulmonary complications. To evaluate the pulmonary effects of low-dose methotrexate, 55 newly diagnosed patients with rheumatoid arthritis (RA) prescribed with MTX were studied prospectively. A significant reduction in percent predicted values of forced expiratory volume (FEV(1)), forced vital capacity (FVC), total lung capacity (TLC), and functional residual capacity (FRC) was observed after 2 years of MTX treatment. A significant increase in the FEV(1):FVC ratio was also observed. In comparison to the normal annual decline in healthy adults, the actual reduction in observed values in the patients was significantly greater (3.2, 6.3, and 6.7 times normal for FEV(1), FVC, and TLC, respectively). PaO(2) and oxygen saturation showed marginal but significant improvement. It was concluded that low-dose MTX treatment in RA might cause an accelerated decline in lung function. Therefore, periodic monitoring of pulmonary function among RA patients started on MTX could be necessary.

Arthritis, Rheumatoid↗