Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Inspiratory Capacity”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,801 records · Page 100Linked to original sources
PubMed1993

A device for overcoming discoordination with metered-dose inhalers.

BACKGROUND: Despite widespread acceptance of metered-dose inhalers (MDIs) in the treatment of asthma, many patients fail to operate these devices correctly. Inability to properly coordinate activation with onset of inhalation is regarded as the major factor in suboptimal MDI therapy. METHODS: We evaluated Autohaler Inhalation Device (3M Pharmaceuticals, St. Paul, Minn.), a breath-activated MDI that is typically activated at a triggering flow rate of approximately 0.5 L/sec. We compared bronchodilator effect of pirbuterol acetate (Maxair), inhaled from Autohaler and a standard MDI, under conditions that ensured optimal technique in 20 patients with asthma. Spirometric variables (forced expiratory volume in 1 second [FEV1], forced expiratory flow between 25% and 75% of vital capacity [FEF25-75], forced vital capacity [FVC]) were measured before and at 15, 30, 60, and 90 minutes after two inhalations of full inspiratory reserve volume for each device. RESULTS: Both devices produced significant and similar bronchodilation. Mean FEV1 increased 32% above baseline 60 minutes after use of Autohaler and 31% after use of a standard MDI. Similar changes were noted in FEF25-75 and FVC for the two devices. Differences between devices for all spirometric variables were not statistically significant. CONCLUSION: Autohaler provides a promising alternative to the standard MDI by overcoming breath-hand discoordination.

Adolescent↗
PubMed1987

Ventilatory muscle dysfunction in patients with bilateral idiopathic diaphragmatic paralysis: reversal by intermittent external negative pressure ventilation.

Bilateral idiopathic diaphragmatic paralysis (BIDP) may result in progressive ventilatory failure. To test the hypothesis that this is in part due to dysfunction of overtaxed inspiratory muscles, we studied 3 patients with BIDP before and after 2, 5, and 18 wk of daily intermittent external surface negative pressure ventilation (ENPV). The patients were evaluated using a zero to 10 functional score (FS) that graded dyspnea, orthopnea, capacity to perform activities of daily living, and ability to work. Pleural (Ppl), abdominal (Pab), and transdiaphragmatic (Pdi) pressures were used as an index of respiratory muscle function. All patients improved their functional score (FS increased 2, 6, and 6, respectively) and their pressure generating ability (Pplmax increased -18, -37, and -46 cm H2O, respectively). Forced vital capacity and functional residual capacity increased in the 2 patients ventilated for longer than 2 wk. These results indicate that ventilatory muscle dysfunction may result from chronic increased work of the inspiratory muscles and that it may improve after periods of intermittent ENPV. This may occur as early as 2 wk after initiation of therapy.

Adult↗
PubMed1979

Alterations in pulmonary function consequent to competitive marathon running.

This study was designed to investigate the mechanisms underlying the significant reductions in vital capacity after marathon racing originally reported over 50 years ago. Spirometric, maximum expiratory flow-volume (MEFV), DLCO and residual volume (RV) measurements were made on 13 runners (11 males and 2 females) 1--2 weeks prior to the marathon, immediately after finishing the race, and again the next day. An average 0.48 L (8.6%) reduction in post-race forced vital capacity (FVC) was accompanied by an equivalent increase in RV. Thus, total lung capacity did not change, and the reduction in FVC was a result of an expiratory rather than an inspiratory limitation. Post-race FEV1 and FEF200-1200 remained unchanged while FEV1-2, FEF1 and FEF2 were reduced 19.7, 26.7 and 23.3%, respectively. Mean DLCO was unchanged. Pulmonary function on the following day was similar to that observed on the control day. These data indicated that after the race, expiratory flow was unaffected at high lung volumes, but was decreased at low lung volumes (within the effort-independent portion of the MEFV curve). The results are compatible with small airway closure occurring at an increased lung volume, which would result in a decreased FVC and an increased RV.

Adult↗
PubMed1993

Three different mask physiotherapy regimens for prevention of post-operative pulmonary complications after heart and pulmonary surgery.

OBJECTIVE: An investigation into the incidence of post-operative complications after thoracic surgery with 3 different physiotherapy masks. DESIGN: A prospective, consecutive, randomized comparison. SETTING: Department of Thoracic and Heart Surgery at a University Hospital. The treatments were performed by experienced and specially trained physiotherapists. PATIENTS: 160 patients were evaluated. 60 patients undergoing heart surgery, 59 patients having pulmonary resection, and 41 patients with exploratory thoracotomy. INTERVENTIONS: In each operative category the patients were treated with one of three face mask systems used in addition to routine chest physiotherapy. These were either continuous positive airway pressure (CPAP), positive expiratory pressure (PEP), or inspiratory resistance - positive expiratory pressure (IR-PEP). MEASUREMENTS AND RESULTS: Post-operative pulmonary complications were assessed by forced vital capacity (FVC), arterial oxygen tension (PaO2), and chest X-ray examination, all measured pre-operatively and on the fourth and ninth post-operative day. The patients filled in a questionnaire expressing their opinion about their mask treatment. There was an equal decrease in FVC, FVC%, and PaO2, and equal frequency of atelectasis in the 3 mask treatments. More patients with the PEP mask favoured their system than did those with the other 2 systems. CONCLUSION: There was no statistically significant difference between the treatments: continuous positive airway pressure (CPAP), positive expiratory pressure (PEP), and inspiratory resistance - positive expiratory pressure (IR-PEP) on post-operative complications. Any of the three treatments may be used as supplement to standard chest physiotherapy.

Blood Gas Analysis↗
PubMed2004

Peak or plateau maximal inspiratory mouth pressure: which is best?

There is no clear evidence as to how maximal inspiratory mouth pressure (PI,max) should be measured, although plateau pressures sustained for 1 s and measured at residual volume (RV) are usually recommended. Peak and plateau PI,max were measured at RV and at functional residual capacity (FRC) in 533 healthy subjects (aged 10-90 yrs) in order to comparably test all PI,max measurements for their predictors, reproducibility and normal values. Plateau pressures accounted for 82.0-86.3%, of peak pressures. Peak and plateau pressures measured at FRC accounted for 84.3-90.5% of pressures at RV, and were highly correlated. Age was negatively predictive and weight and body mass index positively predictive of PI,max, but regression parameters were low. All PI,max measurements were comparable when calculating regression parameters, between-subject variability and reproducibility. In conclusion, peak and plateau maximal inspiratory mouth pressure are comparably useful for the assessment of inspiratory muscle strength and can be reliably measured at functional residual capacity and at residual volume. Regression equations are of low impact in predicting normal values due to the weak influence of demographic and anthropometric factors and to the high unexplained between-subject-variability. Age-related 5th percentiles can indicate the lower limit of the normal range.

Adolescent↗
PubMed2004

Dyspnoea in COPD: can inspiratory muscle training help?

Chronic obstructive pulmonary disease (COPD) is a progressive, common and costly condition. Dyspnoea frequently limits activity and reduces health-related quality of life. In addition to impaired lung function, peripheral muscle deconditioning and respiratory muscle dysfunction also contribute to dyspnoea and reduced exercise capacity. Pulmonary rehabilitation using whole body exercise training improves peripheral muscle function and reduces dyspnoea but does not improve respiratory muscle function. Providing that adequate training intensities are utilised, specific loading of the inspiratory muscles with commercially available hand-held devices can improve inspiratory muscle strength and endurance. Several studies have investigated the effects of inspiratory muscle training on dyspnoea in COPD subjects. Results of these studies are conflicting, most likely reflecting methodological shortcomings including insufficient training load, insensitive outcome measures, and inadequate statistical power. This paper describes the origin of dyspnoea in COPD, with particular attention given to the role of inspiratory muscle dysfunction in its genesis and its possible amelioration through inspiratory muscle training.

Breathing Exercises↗
PubMed1984

Changes in lung, airway, and chest wall function in boys and girls between 8 and 12 yr.

Maximum expiratory flows, maximum inspiratory and expiratory pressures, and lung volumes were measured in 248 8-yr-old and 215 12-yr-old healthy school children. Eight-year-old girls had smaller total lung capacity but higher volume-corrected expiratory flows than boys. Maximum expiratory flow and total lung capacity increased more in girls than in boys between 8 and 12 yr. Girls had a greater increase in residual volume (0.23 liter for girls, 0.16 liter for boys) as well as lower maximum expiratory and inspiratory pressures (P less than 0.001). Girls have smaller lung volumes than boys, so one would expect smaller airways in girls, but girls generate greater flows, indicating that their airways are possibly wider than those of boys. There is also evidence of unequal growth of the airways and air spaces between 8 and 12 yr. Chest wall development appears less in girls than boys and the difference becomes more marked at 12 yr.

Body Height↗
PubMed1980

Effects of expiratory loading on respiration in humans.

We examined the effects of expiratory resistive loads of 10 and 18 cmH2O.l-1.s in healthy subjects on ventilation and occlusion pressure responses to CO2, respiratory muscle electromyogram, pattern of breathing, and thoracoabdominal movements. In addition, we compared ventilation and occlusion pressure responses to CO2 breathing elicited by breathing through an inspiratory resistive load of 10 cmH2O.l-1.s to those produced by an expiratory load of similar magnitude. Both inspiratory and expiratory loads decreased ventilatory responses to CO2 and increased the tidal volume achieved at any given level of ventilation. Depression of ventilatory responses to Co2 was greater with the larger than with the smaller expiratory load, but the decrease was in proportion to the difference in the severity of the loads. Occlusion pressure responses were increased significantly by the inspiratory resistive load but not by the smaller expiratory load. However, occlusion pressure responses to CO2 were significantly larger with the greater expiratory load than control. Increase in occlusion pressure observed could not be explained by changes in functional residual capacity or chemical drive. The larger expiratory load also produced significant increases in electrical activity measured during both inspiration and expiration. These results suggest that sufficiently severe impediments to breathing, even when they are exclusively expiratory, can enhance inspiratory muscle activity in conscious humans.

Adult↗
PubMed1995

Effect of lung volume on forced expiratory flows during rapid thoracoabdominal compression in infants.

The rapid thoracoabdominal compression (RTC) technique is commonly used in pulmonary function laboratories to assess flow-volume relationships in infants unable to produce a voluntary forced expiration maneuver. This technique produces forced expiratory flows over only a small lung volume segment (i.e., tidal volume). It has been argued that the RTC technique should be modified to measure flow-volume relationships over a larger portion of the vital capacity range to imitate the voluntary maximal forced expiratory maneuver obtained in older children and adults. We examined the effect of volume history on forced expiratory flows by generating forced expiratory flow-volume curves by RTC from well-defined inspiratory volumes delineated by inspiratory pressures of 10, 20, 30, and 40 cmH2O down to residual volume (i.e., the reference volume) in seven intubated and anesthetized infants with normal lungs [age 8.0 +/- 2.0 (SE) mo, weight 6.7 +/- 0.6 kg]. We compared maximal expiratory flows at isovolume points (25 and 10% of forced vital capacity) and found no significant differences in maximal isovolume flow rates measured from the different lung volumes. We conclude that there is no obvious need to initiate RTC from higher lung volumes if the technique is used for flow comparisons. However, compared with measurements of maximal flows at functional residual capacity by RTC from end-tidal inspiration, the initiation of RTC from a defined and reproducible inspiratory level appears to decrease the intrasubject variability of the maximal expiratory flows at low lung volumes.

Abdomen↗
PubMed1984

Maximal ventilation at rest and exercise in patients with chronic pulmonary disease.

74 subjects of different ages: normal children, 19 boys (A) and 7 girls (C) aged between 11 and 15 years; asthmatic boys (n = 7, group B) and girls (n = 7, group D), with similar ages; normal male adult subjects (n = 10, group E) and pulmonary patients with restrictive (n = 8, group G) or obstructive (n = 16, group F) ventilatory impairment, were submitted to measurements of vital capacity (VC), forced expiratory volume in 1 s, (FEV1), maximal voluntary ventilation (MVV), maximal peak expiratory (PEF) and inspiratory (PIF) flows at rest, and two maximal exercise stress tests in which the ventilation at maximal exercise (MEV) were retained. Indirect MVV was obtained by multiplying the FEV1 by 35 and 37.5. The correlation coefficients between MVV and VC, FEV1, PEF and PIF were always as high as r greater than 0.76. (p less than 0.001), with a discrepancy between the calculated and measured MVV. The average ratio MVV/FEV1 always exceeds 39 and is much higher in groups B, C and G. The mean percent values of the ratio MEV/MVV were 0.63 in normal men and 0.74 in normal boys. In patients, this ratio is higher than in adult normals: F = 0.81 and G = 0.88, and is not due to methodological errors, but seems to correspond to several physiological features playing only a role during exercise (MEV). This work shows the difficulty in predicting correctly the MVV at rest and in assessing the ventilatory reserve during maximal exercise in chronic pulmonary patients.

Adolescent↗
PubMed1999

Paralysis of ventilated newborn babies does not influence resistance of the total respiratory system.

Paralysis with pancuronium bromide is used in newborn infants to facilitate ventilatory support during respiratory failure. Changes in lung mechanics have been attributed to paralysis. The aim of this study was to examine whether or not paralysis per se has an influence on the passive respiratory mechanics, resistance (Rrs) and compliance (Crs) of the respiratory system in newborn infants. In 30 infants with acute respiratory failure, Rrs was measured during paralysis with pancuronium bromide and after stopping pancuronium bromide (group A). Rrs was also measured in an additional 10 ventilated infants in a reversed fashion (group B): Rrs was measured first in nonparalysed infants and then they were paralysed, mainly for diagnostic procedures, and the Rrs measurement repeated. As Rrs is highly dependent on lung volume, several parameters, that depend directly on lung volume were recorded: inspiratory oxygen fraction (FI,O2), arterial oxygen tension/alveolar oxygen tension (a/A) ratio and volume above functional residual capacity (FRC). In group A, the Rrs was not different during (0.236+/-0.09 cmH2O x s x mL(-1)) and after (0.237+/-0.07 cmH2O x s x mL(-1)) paralysis. Also, in group B, Rrs did not change (0.207+/-0.046 versus 0.221+/-0.046 cm x s x mL(-1) without versus with pancuronium bromide). FI,O2, a/A ratio and volume above FRC remained constant during paralysis. These data demonstrate that paralysis does not influence the resistance of the total respiratory system in ventilated term and preterm infants when measured at comparable lung volumes.

Acute Disease↗
PubMed1999

Cerebral desaturation during exercise reversed by O2 supplementation.

The combined effects of hyperventilation and arterial desaturation on cerebral oxygenation (ScO2) were determined using near-infrared spectroscopy. Eleven competitive oarsmen were evaluated during a 6-min maximal ergometer row. The study was randomized in a double-blind fashion with an inspired O2 fraction of 0.21 or 0.30 in a crossover design. During exercise with an inspired O2 fraction of 0.21, the arterial CO2 pressure (35 +/- 1 mmHg; mean +/- SE) and O2 pressure (77 +/- 2 mmHg) as well as the hemoglobin saturation (91.9 +/- 0.7%) were reduced (P < 0.05). ScO2 was reduced from 80 +/- 2 to 63 +/- 2% (P < 0.05), and the near-infrared spectroscopy-determined concentration changes in deoxy- (DeltaHb) and oxyhemoglobin (DeltaHbO2) of the vastus lateralis muscle increased 22 +/- 3 microM and decreased 14 +/- 3 microM, respectively (P < 0.05). Increasing the inspired O2 fraction to 0.30 did not affect ventilation (174 +/- 4 l/min), but arterial CO2 pressure (37 +/- 2 mmHg), O2 pressure (165 +/- 5 mmHg), and hemoglobin O2 saturation (99 +/- 0.1%) increased (P < 0. 05). ScO2 remained close to the resting level during exercise (79 +/- 2 vs. 81 +/- 2%), and although the muscle DeltaHb (18 +/- 2 microM) and DeltaHbO2 (-12 +/- 3 microM) were similar to those established without O2 supplementation, work capacity increased from 389 +/- 11 to 413 +/- 10 W (P < 0.05). These results indicate that an elevated inspiratory O2 fraction increases exercise performance related to maintained cerebral oxygenation rather than to an effect on the working muscles.

Adult↗
PubMed1988

Lung function disturbances versus respiratory muscle fatigue in patients with systemic lupus erythematosus.

In 23 consecutive patients (mean age, 38.6 years) with systemic lupus erythematosus (SLE) and in 17 healthy subjects (mean age, 37.5 years) fatigue of respiratory (diaphragm, musculi intercostales externi) and leg muscles (musculus gastrocnemius) was determined comparatively by electromyography. Additionally, routine lung function parameters, including maximum inspiratory (PImax) and expiratory (PEmax) mouth pressures, were measured. The SLE patients showed lower values of vital capacity (VC), total lung capacity (TLC), thoracic gas volume (TGV), FEV1, PImax and PEmax than the healthy controls, while FEV1/VC, residual volume and specific airway conductance were not significantly different in either group. Lung compliance, corrected for TGV, was normal in the SLE group. Breathing through stenoses with increasing resistances resulted in fatigue of the diaphragm in 73% of the SLE group and in 41% of the control group. The corresponding values of the external intercostal muscles were 74% (SLE group) and 29% (control group). Electromyographic signs of respiratory and leg muscle fatigue occurred at lower loads in the SLE group than in the healthy subjects. The pattern of lung function data in patients with SLE was characteristic neither of lung restriction nor of airway obstruction. Respiratory muscle weakness can explain the decrease in TLC, VC, TGV, FEV1, PImax and PEmax.

Adult↗
PubMed1987

Nutritional supplementation in ambulatory patients with chronic obstructive pulmonary disease.

We examined the effect of nutritional supplementation for 8 wk on respiratory muscle function (RMF) in 21 malnourished patients with COPD. Patients were randomized to a fed group or to a control group. Patients in the fed group were provided with an enteral formula in addition to their usual diet. Daily calorie and protein intake and weekly anthropometric measures were made. Pulmonary function tests were measured on Weeks 1, 4, and 8. Respiratory muscle strength was measured by means of maximal inspiratory and expiratory pressures (MIP), (MEP), and respiratory muscle endurance was measured by the maximal sustained ventilatory capacity (MSVC). The mean weight of the fed group increased from 52.2 +/- 6.4 to 53.3 +/- 6.9 kg (NS). The mean daily caloric intake of the fed group was significantly increased during the study (p less than 0.02). The mean calorie intake during the study of the fed group was 174 +/- 17% of the estimated basal energy expenditure. During the study period, no change was observed in anthropometric measures, pulmonary function studies, or RMF. Because patients tend to decrease their own food intake while receiving enteral formulas, it is difficult to provide sufficient calories and protein needed to effect changes in nutritional status and RMF in an outpatient COPD population. In addition, we compared RMF in 12 poorly nourished male patients (87.6 +/- 6.1% of ideal body weight) and 13 well-nourished male patients with severe COPD. Both groups had comparable degrees of air-flow limitation and hyperinflation. No difference was noted between the groups in either MIP, MEP, or MSVC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Pulmonary intravascular lymphomatosis: presentation with dyspnea and air trapping.

Intravascular lymphomatosis (IVL) is a rare lymphoid neoplasm that is typically of B-cell lineage and characterized by proliferation of malignant cells within small arterioles, capillaries, and venules. We report a patient with pulmonary IVL who presented clinically with progressive dyspnea, fever, and a dry cough. Pulmonary function tests revealed a marked decrease in diffusion capacity with airflow obstruction and severe air trapping. High-resolution CT (HRCT) of the chest with inspiratory and expiratory images revealed mosaic attenuation consistent with air trapping. Transbronchial biopsies revealed the diagnosis of IVL with capillary expansion in the alveolar and peribronchiolar interstitial tissue. IVL should be considered in the differential diagnosis of a patient with an interstitial lung disease, air trapping on pulmonary function tests, and mosaic attenuation on HRCT. Transbronchial biopsies may be the initial diagnostic procedure of choice.

Dyspnea↗
PubMed1992

[Evaluation of physical fitness and exercise performance in patients with chronic pulmonary emphysema].

Physical fitness was studied in patients with chronic pulmonary emphysema using Kraus-Weber methods in addition to pulmonary function and exercise tolerance. In Kraus-Weber tests, explosive strength of abdominal muscles in these patients were within the normal range, but both abdominal and back muscle endurance were significantly diminished compared to age-matched controls. On the other hand, flexibility was not different between the patients and the controls, although large variation was present. Exercise performance as assessed by 6 minutes' walk distance in patients was significantly correlated with FEV1.0, DLco and maximal inspiratory mouth pressure, as well as explosive strength of abdominal muscles and abdominal and back muscle endurance capacity. Treadmill walking training for 20 minutes with a load greater than 80% VO2max, twice a week for 2 months was performed in 11 patients with mild to moderate pulmonary emphysema. Six minutes' walk distance (6MD) was significantly prolonged with improvement of back muscle endurance and flexibility. Another walking training consisting of five repetitions of two minutes' near maximal walking and a two minute interval of rest was performed in 6 patients with severe pulmonary emphysema. 6MD tended to increase with improvement of both back and abdominal muscle endurance. However, pulmonary function tests and VO2max showed no significant changes after both types of training. Improved walked distance after the training was significantly correlated with improved VO2 at AT. Furthermore VO2, VE, HR and lactate production during exercise at the same load were significantly decreased compared to pre-training. Dyspnea sensation measured by modified Borg scale during exercise was improved after the training. It is concluded that a physical training program adapted to the condition of the individual patients could improve exercise performance, and should be prescribed in addition to medication.

Aged↗
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↗
PubMed1989

Weaning from mechanical ventilation: adjunctive use of inspiratory muscle resistive training.

We used inspiratory resistive training (IRT) in an effort to improve the respiratory muscle endurance of 27 patients with respiratory failure who had failed repeated weaning attempts using standard techniques. Seven patients had primary neuromuscular diseases; the other 20 had primary lung diseases. All patients had stable respiratory failure, without gross malnutrition or electrolyte disorders. Their best initial T-piece duration averaged 6.4 +/- 8.4 (SD) h, with pHa 7.33 +/- 0.09 and PCO2 63 +/- 4 torr at the end of the T-piece trial. We provided a mean of five weekly training sessions of spontaneous breathing through an adjustable nonlinear resistor, with gradually increasing duration and resistance. When initial T-piece tolerance was less than 2 h, two to ten breaths of mechanical ventilation were provided during IRT sessions. No training session exceeded 30 min, and mechanical ventilation was provided between IRT sessions. Under this regimen, maximal inspiratory pressure improved from -37 +/- 15 to -46 +/- 15 cm H2O (p less than .001) and vital capacity improved from 561 +/- 325 to 901 +/- 480 ml (p less than .001). Twelve of the 27 patients were successfully weaned after 10 to 46 days; five more were weaned to nocturnal ventilation, for a total of 63%. We conclude that IRT can improve respiratory muscle strength and endurance in patients with respiratory failure, and can allow many of them to be weaned from mechanical ventilation.

Aged↗

Refine your search to explore more results.