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 1,297 records · Page 72Linked to original sources
PubMed2000

Respiratory muscle endurance training in chronic obstructive pulmonary disease: impact on exercise capacity, dyspnea, and quality of life.

Inspiratory muscle training may have beneficial effects in certain patients with chronic obstructive pulmonary disease (COPD). Because of the lack of a home training device, normocapnic hyperpnea has rarely been used as a training mode for patients with COPD, and is generally considered unsuitable to large-scale application. To study the effects of hyperpnea training, we randomized 30 patients with COPD and ventilatory limitation to respiratory muscle training (RMT; n = 15) with a new portable device or to breathing exercises with an incentive spirometer (controls; n = 15). Both groups trained twice daily for 15 min for 5 d per week for 8 wk. Training-induced changes were significantly greater in the RMT than in the control group for the following variables: respiratory muscle endurance measured through sustained ventilation (+825 +/- 170 s [mean +/- SEM] versus -27 +/- 61 s, p < 0.001), inspiratory muscle endurance measured through incremental inspiratory threshold loading (+58 +/- 10 g versus +21.7 +/- 9.5 g, p = 0.016), maximal expiratory pressure (+20 +/- 7 cm H(2)O versus -6 +/- 6 cm H(2)O, p = 0.009), 6-min walking distance (+58 +/- 11 m versus +11 +/- 11 m, p = 0.002), V O(2peak) (+2.5 +/- 0.6 ml/kg/min versus -0.3 +/- 0.9 ml/kg/min, p = 0.015), and the SF-12 physical component score (+9.9 +/- 2.7 versus +1.8 +/- 2.4, p = 0.03). Changes in dyspnea, maximal inspiratory pressure, treadmill endurance, and the SF-12 mental component score did not differ significantly between the RMT and control groups. In conclusion, home-based respiratory muscle endurance training with the new device used in this study is feasible and has beneficial effects in subjects with COPD and ventilatory limitation.

Aged↗
PubMed1982

Improvement in lung mechanics as a function of age in the infant with severe bronchopulmonary dysplasia.

Pulmonary function tests were performed in two groups of infants with bronchopulmonary dysplasia; a group less than 7 months of age with severe ventilator-dependent respiratory failure (Group A), and a group 7-22 months of age during resolution of their disease (Group B). Group A patients had significantly elevated minute volume, low specific compliance, elevated inspiratory and expiratory pulmonary resistance, and low functional residual capacity. Group B patients also demonstrated elevated minute volume, whereas specific compliance, inspiratory pulmonary resistance and functional residual capacity were within normal limits, and expiratory pulmonary resistance was only slightly above normal. With the exception of minute volume, the differences between the groups were significant (P less than 0.05). Sequential studies of resistance and compliance over 4-5 months in two patients in the younger group demonstrated values that approached or achieved normal range. It is concluded that pulmonary mechanics improve with age in the infant with severe bronchopulmonary dysplasia.

Aging↗
PubMed1996

Effect of pattern of preceding inspiration on FEV1 in asthmatic children.

In adults, both peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1) are significantly influenced by the time course of the inspiration preceding the forced expiration. The aim of this study was to evaluate the effects of three different inspiratory manoeuvres on PEF, FEV1, and forced vital capacity (FVC) in asthmatic children. Twenty five symptomless asthmatic children performed forced expiration preceded by three different inspiratory manoeuvres, which consisted of: a rapid inspiration with a 2 s end-inspiratory breathhold (Manoeuvre No. 1); a rapid inspiration without an end-inspiratory breathhold (Manoeuvre No. 2); and a slow inspiration lasting about 5 s with an end-inspiratory breathhold of at least 4 s (Manoeuvre No. 3). All manoeuvres were performed in a randomly assigned sequence each morning for three consecutive days. In each session, the manoeuvres were repeated three times and the highest value was chosen. Both FVC and FEV1 obtained with Manoeuvre No. 3 were significantly lower than the corresponding values obtained with Manoeuvre Nos. 1 and 2. The mean (SD) FVC values were 2.76 (0.66) L with Manoeuvre No. 1, 2.67 (0.58) L with Manoeuvre No. 2 and 2.52 (0.52) L with Manoeuvre No. 3. The corresponding values of FEV1 were 2.25 (0.53), 2.22 (0.53) and 2.07 (0.44) L, respectively. By contrast, the values of PEF, obtained with a portable peak flow meter, were similar with the three different inspiratory manoeuvres. The results of this study show that in symptomless asthmatic children the preceding inspiratory manoeuvre may influence forced vital capacity and forced expiratory volume in one second. Hence, in order to reduce variability due to interference by physiological factors and so improve reproducibility of pulmonary function tests, the inspiratory manoeuvres must be accurately standardized.

Asthma↗
PubMed1975

Factors influencing the measurement of closing volume.

The various factors influencing closing volume were studied by performing the single-breath N2 test on 9 healthy nonsmokers. Time of day, day of the week, and preceding volume history had no effect on either closing volume or alveolar plateau. Slow inspiratory flow resulted in larger ratio of closing volume to vital capacity, ratio of closing capacity to total lung capacity, and change in N2 concentration than fast inspiratory flow. Voluntary regulation of the expiratory flow resulted in smaller ratios of closing volume to vital capacity and closing capacity to total lung capacity than when flow was regulated by a resistance. Prolonged breath holding of the inspired O2 led to larger ratio of closing volume to vital capacity and ratio of closing capacity to total lung capacity. To obtain uniform, comparable closing volumes, it is suggested that the subject inspire slowly, control expiratory flow (preferably voluntarily), and not pause between inspiration and expiration.

Adult↗
PubMed2001

Awake respiratory function in patients with the obstructive sleep apnoea syndrome.

INTRODUCTION: The flow-volume curves of patients with obstructive sleep apnoea (OSA) obtained during the awake state are frequently abnormal. OBJECTIVE: To determine 1) the relationship between the awake respiratory function and the severity of sleep-disordered breathing in a group of Malaysian patients with the OSA syndrome and 2) the frequency of flow-volume curve abnormality in these patients. MATERIALS AND METHODS: A retrospective analysis of the data from respiratory function tests during wakefulness and nocturnal polysomnography was performed on 48 patients with OSA. The severity of OSA was defined by the apnoea-hypopnoea index (AHI) and the lowest oxygen saturation during sleep (SpO2nadir). RESULTS: AHI had a significant relationship with alveolar-arterial oxygen gradient (r = 0.34, p = 0.046) and SpO2nadir (r = -0.49, p < 0.001) but not with any anthropometric parameter or the other awake respiratory function variables measured. SpO2nadir had a significant relationship with body mass index (r = -0.54, p < 0.001), neck circumference (r = -0.39, p = 0.013), awake room air PaO2 (r = 0.61, p < 0.001), alveolar-arterial oxygen gradient (r = -0.41, p = 0.015) and baseline supine SpO2 (r = 0.53, p < 0.001). There was no correlation between SpO2nadir and any spirometric or static lung volume parameters. The maximum inspiratory and maximum expiratory flow-volume curves of 26 patients (54%) showed a ratio of forced expiratory flow to forced inspiratory flow at mid-vital capacity (FEF50/FIF50) greater than one. In addition, flow oscillations (the "sawtooth" sign) were noted in the inspiratory and/or expiratory flow-volume curves of 21 patients (44%), 9 of whom did not have an FEF50/FIF50 > 1. Altogether, the maximum flow-volume curves during wakefulness of 35 (73%) of the 48 patients showed variable upper airway obstruction and/or flow oscillations. However, the presence of these two upper airway abnormalities, either occurring alone or together did not have an effect on the severity of OSA as measured by the AHI or SpO2nadir. CONCLUSIONS: Abnormalities of the flow-volume loop consistent with inspiratory flow limitation and/or upper airway instability during wakefulness are common in patients with the OSA syndrome. The degree of oxygen desaturation during sleep in these patients is related to their awake oxygenation status.

Adult↗
PubMed2005

Inspiratory muscle training in adults with chronic obstructive pulmonary disease: a systematic review.

The purpose of this study was to conduct a systematic review to determine the effect of inspiratory muscle training (IMT) on inspiratory muscle strength and endurance, exercise capacity, dyspnea and quality of life for adults with chronic obstructive pulmonary disease (COPD). A systematic review of the literature was conducted according the Cochrane Collaboration protocol using Medline and CINAHL. Nineteen of 274 extracted articles met the inclusion criteria and addressed comparisons of interest which included: IMT versus sham; IMT versus no intervention; low- versus high-intensity IMT; and two different modes of IMT. Thirteen meta-analyses were reported. Results indicate that targeted resistive or threshold IMT was associated with significant improvements in some outcomes of inspiratory muscle strength (PI(max) (cm H2O)) and endurance (Inspiratory Threshold Loading (kPa)), exercise capacity (Borg Scale for Respiratory Effort (modified Borg scale), Work Rate maximum (Watts)), and dyspnea (Transition Dyspnea Index), whereas IMT without a target or not using threshold training did not show improvement in these variables. There was no conclusive evidence regarding quality of life measures. IMT is effective for adults with COPD when using threshold or targeted devices that control or provide a target for training intensity.

Adolescent↗
PubMed2001

Inspiratory muscle training in patients with COPD: effect on dyspnea, exercise performance, and quality of life.

OBJECTIVE: The aim of the study was to assess the effect of target-flow inspiratory muscle training (IMT) on respiratory muscle function, exercise performance, dyspnea, and health-related quality of life (HRQL) in patients with COPD. PATIENTS AND METHODS: Twenty patients with severe COPD were randomly assigned to a training group (group T) or to a control group (group C) following a double-blind procedure. Patients in group T (n = 10) trained with 60 to 70% maximal sustained inspiratory pressure (SIPmax) as a training load, and those in group C (n = 10) received no training. Group T trained at home for 30 min daily, 6 days a week for 6 months. MEASUREMENTS: The measurements performed included spirometry, SIPmax, inspiratory muscle strength, and exercise capacity, which included maximal oxygen uptake (VO(2)), and minute ventilation (VE). Exercise performance was evaluated by the distance walked in the shuttle walking test (SWT). Changes in dyspnea and HRQL also were measured. RESULTS: Results showed significant increases in SIPmax, maximal inspiratory pressure, and SWT only in group T (p < 0.003, p < 0.003, and p < 0.001, respectively), with significant differences after 6 months between the two groups (p < 0.003, p < 0.003, and p < 0.05, respectively). The levels of VO(2) and VE did not change in either group. The values for transitional dyspnea index and HRQL improved in group T at 6 months in comparison with group C (p < 0.003 and p < 0.003, respectively). CONCLUSIONS: We conclude that targeted IMT relieves dyspnea, increases the capacity to walk, and improves HRQL in COPD patients.

Aged↗
PubMed2001

Diaphragmatic function in patients with chronic left ventricular failure.

The aim of this paper is to evaluate the function of respiratory muscles in-patients with chronic moderate left ventricular failure (LVF), and its contribution to the pathophysiology of dyspnea and fatigue. We have studied 20 male patients with LVF, classes II and III of New York Heart Association (NYHA), mean age 66.9+/-10 years (GI) and 19 male aged-matched controls without cardiopulmonary disease mean age 64.6+/-8.4 years (GII). The evaluation included (a) methods derived from volitional manoeuvres, maximal inspiratory pressures at Functional Residual Capacity; maximal expiratory pressures at total lung capacity (TLC); nasal sniff; oesophageal sniff and transdiaphragmatic pressures; (b) methods derived from non-volitional manoeuvres, using bilateral cervical magnetic stimulation of the phrenic nerves, measuring the following twitch pressures (oesophageal, gastric and the transdiaphragmatic). With volitional manoeuvres we have not found statistically significant differences between the two groups: maximal expiratory pressures (cmH(2)O), GI 138+/-42; GII 152+/-40; P=NS and maximal inspiratory pressures (cmH(2)O), GI 74.1+/-22; GII 85+/-16; P=NS. However, these values were significantly lower than those obtained with sniff manoeuvres, nasal sniff (cmH(2)O), GI 95.6+/-22; GII 99.6+/-16; P=NS and oesophageal sniff (cmH(2)O), GI 96.2+/-20; GII 97.5+/-18; P=NS. There were no significant differences between nasal sniff and oesophageal sniff. Using cervical magnetic stimulation, we also didn't find a significant difference for transdiaphragmatic twitch between groups, but the contribution of the diaphragm to the transdiaphragmatic pressure was lower in patients with LVF since the oesophageal twitch was lower (cmH(2)O), GI 11.4+/-3.4; GII 16.3+/-6.8; P<0,004. In conclusion, the contribution of the diaphragm to total ventilation in-patients with moderate LVF is preserved. However, its capacity to generate negative intra-thoracic pressures is decreased since there is a significant decrease in oesophageal twitch. So, it seems that the diaphragm is the first inspiratory muscle to be affected in patients with moderate LVF.

Journal Article↗
PubMed1983

Maximal shortening of inspiratory muscles: effect of training.

Normal subjects can increase their vital capacity by appropriate training. We tested whether that change can be achieved by greater maximal shortening of the inspiratory muscles without concomitant increases in peak static inspiratory pressures. Sixteen healthy volunteers participated in the study: eight were randomly assigned to make 20 inhalations to total lung capacity, held for 10 s with the glottis open, each day for 6 wk; the remainder served as nontraining controls. Before and after the 6-wk study period, we made multiple determinations of lung volumes and of curves relating lung volume to maximal static inspiratory (and expiratory) pressure. Control subjects had no significant changes from base line in any variable. In the training group, the mean vital capacity increased 200 +/- 74 ml (P less than 0.05) or 3.9 +/- 1.3% (P less than 0.02), without a significant change in residual volume. After training, the mean maximal inspiratory pressure at the airway opening (PI) at a lung volume equal to the base-line total lung capacity was 27 +/- 8 cmH2O in this group (vs. zero before training; P less than 0.02). Values of PI in the mid-vital capacity range did not change. We conclude that in response to appropriate training stimuli inspiratory muscles can contract to shorter minimal lengths, a capacity potentially important in progressive pulmonary hyperinflation.

Adolescent↗
PubMed1999

Pulmonary function pre- and post-total laryngectomy.

Pulmonary function pre- and post-total laryngectomy was assessed in 16 patients without overt inspiratory stridor preoperatively. It could be shown that total laryngectomy is associated with a significant decrease in vital capacity and in an increase in inspiratory flow-volume values 9 days postoperatively. The inspiratory values tended to increase slightly over the next half year. The measured expiratory flow-volume values were preoperatively already significantly lower than the predicted values, and no significant changes could be observed immediately after the operation nor after 6 months. These alterations have to be taken into account when judging the pulmonary function after total laryngectomy.

Adult↗
PubMed2001

Volume of activation of the Hering-Breuer inflation reflex in the newborn infant.

Although the Hering-Breuer inflation reflex (HBIR) is active within tidal breathing range in the neonatal period, there is no information regarding whether a critical volume has to be exceeded before any effect can be observed. To explore this, effects of multiple airway occlusions on inspiratory and expiratory timing were measured throughout tidal breathing range using a face mask and shutter system. In 20 of the 22 healthy infants studied, there was significant shortening of inspiration because the volume at which occlusion occurred rose from functional residual capacity (FRC) to end-inspiratory volume [14.9% reduction in inspiratory time (per ml/kg increase in lung volume at occlusion)]. All infants showed a significant increase in expiratory time [17.1% increase (per ml/kg increase in lung volume at occlusion)]. Polynomial regression analyses revealed a progressive increase in strength of HBIR from FRC to approximately 4 ml/kg above FRC. Eighteen infants showed no further shortening of inspiratory time and 10 infants no further lengthening of expiratory time with increasing occlusion volumes, indicating maximal stimulation of the reflex had been achieved. There was a significant relationship between strength of HBIR and respiratory rate, suggesting that HBIR modifies the breathing pattern in the neonatal period.

Humans↗
PubMed1989

Reversible respiratory muscle weakness in hyperthyroidism.

Breathlessness is a common complaint in patients with hyperthyroidism, and respiratory failure requiring artificial ventilation, although rare, can occur. While a proximal myopathy is frequently recognized, diaphragm muscle function has not hitherto been studied in detail in thyrotoxicosis. The strength of the quadriceps femoris and respiratory muscles was therefore assessed in seven consecutive thyrotoxic patients, on presentation and during medical treatment, when euthyroid. Prior to therapy, reduced quadriceps muscle strength, vital capacity, and global expiratory and inspiratory muscle strength were found. Diaphragmatic weakness was present in one of four patients studied by measuring transdiaphragmatic pressures during maximal sniffs and during bilateral phrenic nerve stimulation at 1 Hz (twitch). After treatment, significant improvement occurred in quadriceps muscle strength, vital capacity, and global respiratory muscle strength. Sniff and twitch transdiaphragmatic pressures also increased significantly. These results indicate that respiratory muscle weakness occurs in hyperthyroidism and that such weakness is reversible with medical treatment. It is important to realize that respiratory muscles may be directly affected when assessing thyrotoxic patients with breathlessness, as severe involvement of the respiratory muscles may cause respiratory failure.

Chronic Disease↗
PubMed1987

Effect of theophylline on respiratory neuromuscular drive.

To investigate the possible mechanisms by which theophylline affects the control of ventilation, neuromuscular drive and ventilatory function were examined in 7 healthy men receiving an incremental intravenous aminophylline dosing schedule to achieve plasma theophylline concentrations of 5, 10, and 15 micrograms/ml. As compared with the baseline (predose) values, the 3 incremental aminophylline doses significantly (p less than 0.05 to 0.01) increased occlusion pressure (P0.1) and maximum inspiratory pressure static (MIPS) at functional residual capacity (FRC). This was not observed for ventilatory flow (V), tidal volume (VT), inspiratory time to total breathing cycle time ratio (Ti/Ttot) VT/Ti, and effective impedance [P0.1/VT/Ti)]. When maximum electrical activity of diaphragm (Edimax) and transdiaphragmatic pressure (Pdimax) were examined in 3 of the 7 subjects, Pdi/Edi tended to increase with increasing theophylline concentrations, while Edimax did not. Our results suggest that the increase in P0.1 during the increase in aminophylline dose is caused by an improvement in respiratory muscle contractility, rather than by a central effect or by an increase in neural drive.

Adult↗
PubMed1989

Changes in selected pulmonary functions in patients diagnosed with myasthenia gravis.

Patients with myasthenia gravis (MG) face major pulmonary problems as a part of the disease process. In this descriptive study, changes in selected pulmonary functions (respiratory rate, negative inspiratory force, tidal volume and forced vital capacity) in 14 patients diagnosed with mild or moderate MG were measured every two hours from 8:00 a.m. to 8:00 p.m. Females comprised 64% of the sample while 36% were males. All subjects received anticholinesterase medication, and some subjects received additional treatment modalities. Most of the subjects were nonsmokers or previous smokers, but two subjects continued to smoke. Ninety-three percent of the sample had forced vital capacities less than 60% of their predicted values. Myasthenic forced vital capacities were significantly lower (p = .0000) than those predicted for normal subjects. The inspiratory force for the sample was low at 8:00 a.m. as well as in females over 55 years of age. There was a wide variation in tidal volume. The comparison of myasthenic values for respiratory rate, inspiratory force and tidal volume to normal values derived from random tables and prediction equations was not significant. The major implications from this study are the need to assess pulmonary function in the hospitalized myasthenic every two hours, and the need for a program of coughing, deep breathing and sighing after medication administration when muscles are strongest.

Adolescent↗
PubMed1999

Nasal dilator strips increase maximum inspiratory flow via nasal wall stabilization.

OBJECTIVE: Inspiratory flow limitation associated with collapse of the nasal vestibular walls is a feature of nasal breathing at high ventilatory levels. We examined whether an external nasal dilator strip (ENDS) device (Breathe Right, CNS Inc., Chanhassen, MN) influences maximum inspiratory and expiratory flow rates. STUDY DESIGN: Prospective, randomized. METHODS: We studied 20 Caucasian subjects (13 female, 7 male; age range, 16-49 y) performing maximum-effort nasal flow-volume loop studies with (ENDS) and without ENDS (control) and following topical nasal decongestant (oxymetazoline hydrochloride, 0.2 mg per nostril). RESULTS: ENDS increased peak inspiratory flow from 2.55+/-0.24 L/s (mean+/-standard error [SE]) to 2.86+/-0.25 L/s and forced inspiratory flow at 50% of vital capacity from 2.23+/-0.24 L/s to 2.53+/-0.24 L/s (both, P<.0001), but had no effect on maximum expiratory flows. Nasal decongestant increased the forced expiratory volume in 1 second from 3.39+/-0.22 L/s to 3.59+/-0.22 L/s and the average forced expiratory flow over 25% to 75% of vital capacity from 3.31+/-0.31 L/s to 3.61+/-0.28 L/s (both, P< or = .008), but had no effect on maximum inspiratory flows. The combination of decongestant and ENDS increased both inspiratory and expiratory maximum flows. CONCLUSION: Since ENDS selectively increases maximum nasal inspiratory flow rates, we conclude that ENDS increases inspiratory nasal patency during maximum inspiratory efforts through the nose by supporting the lateral nasal vestibular walls and making them more resistant to collapse.

Adolescent↗
PubMed1981

Fixed performance oxygen masks. Hypoxic hazard of low-capacity drugs.

Four recently introduced low-capacity fixed performance oxygen therapy masks have been compared with the established Ventimask design. Under conditions of varying peak inspiratory flow rate the low-capacity devices all permit a variable amount of air admixture with a consequent fall in the inspired oxygen concentration. It is concluded that low-capacity venturi masks are not true fixed performance devices under all circumstances. The Ventimasks satisfy their specifications under all test conditions. A case is made for more rigorous assessment of new so-called "fixed performance" oxygen therapy devices before marketing is permitted.

Equipment Design↗
PubMed1988

Physiologic assessment of lung function in patients undergoing laser photoresection of tracheobronchial tumors.

We performed YAG laser photoresection in 11 patients with tracheal or mainstem bronchial obstruction due to malignant or benign disorders. We used maximal inspiratory-expiratory flow-volume loops and expiratory volume-time plots to assess air flow limitation. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow (PEF) and iso-volume maximal flows at 50 percent of forced inspiratory and expiratory volume were calculated. Spirograms and flow-volume loops were repeated within 12 to 72 hours of laser resection. All patients had flattened expiratory limbs on their flow-volume loops. All spirometric parameters increased significantly following laser photoresection. In particular, peak flow improved in all patients, and FEV1 improved in nine of 11 patients, even though four patients had moderate to severe obstructive ventilatory defects which persisted after resection and were probably due to longstanding chronic obstructive pulmonary disease. We conclude that flow-volume loops and spirometry are helpful in assessing the site and nature of malignant large airway obstructive processes and, moreover, provide reliable information for evaluating the efficacy of laser photoresection. Serial physiologic studies indicate changes in the caliber of the upper airways and can be used as a simple means of following these patients.

Adult↗
PubMed1994

The unweanable patient.

Inspiratory muscles can be exerted to their maximal limits during situations of: 1) high ventilatory demands, such as in exercise; and 2) during cases of high force demands, as in obstructive or restrictive diseases. In either circumstance, the level of sustainable activity (many hours) seems to be about half of the subject's maximal ventilatory capacity (MVC) or their maximal inspiratory pressure (MIP), respectively. The natural history of chronic hypercapnia in chronic obstructive pulmonary disease (COPD) or in neuromuscular disease suggests that spontaneous ventilation is set at a level below that which will trigger muscle fatigue, even if this lower level results in "chronic ventilatory failure". When this type of patient suffers a pathology that further decreases their global respiratory muscle function or increases their load, we have the makings of an unweanable patient; the mechanical ventilator ultimately replaces the lost inspiratory muscle function. Given time for the muscle to recover force and a reduction of the loads should, thus, be the therapeutic focus.

Humans↗