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PubMed2003

Predicting oxygen uptake for men and women with moderate to severe chronic obstructive pulmonary disease.

OBJECTIVE: To develop regression equations for estimating peak oxygen consumption (Vo(2)) for men and women with moderate to severe chronic obstructive pulmonary disease (COPD) from the 6-minute walk test (6MWT). DESIGN: Multivariate analysis of patient pulmonary function and exercise gas exchange indices to 2 outcomes for the 6MWT (distance ambulated, calculated work [6M(WORK)]). SETTING: A university hospital and clinics. PARTICIPANTS: A total of 124 patients (90 men 34 women; age range, 45\N81y), from the community, with moderate to very severe COPD. Forced expiratory volume in 1 second (FEV(1)) ranged from.70 to 2.79L/min, forced vital capacity (FVC) ranged from 1.73 to 5.77L, and FEV(1)/FVC ranged from 24% to 69%. All patients were in stable condition at the time of testing and were on a stable drug regimen. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Pulmonary function testing was completed according to American Thoracic Society criteria. Cycle ergometry with gas exchange, by using a ramp protocol, was completed. The 6MWT was done in the hospital corridor, with distances recorded after each minute. Work capacity by each method was reduced from the normal predicted. RESULTS: Peak oxygen uptake (Vo(2)) averaged 1184+/-302mL/min for men and 860+/-256mL/min for women (58%, 68% of predicted, respectively). Ventilatory reserve was limited at an achieved peak ventilation (Ve) of 79.9%+/-19.1% of predicted. Borg scores for dyspnea and leg fatigue were equivalent for each test modality, with leg fatigue being slightly higher for each gender. 6M(WORK) for the 6MWT was the strongest independent predictor of peak Vo(2) (r=.81, P<.0001), whereas that for distance ambulated was correlated at r equal to.54 (P<.0001). This is a 36% improvement in the variance accounted for by the application of 6M(WORK) as the outcome for the 6MWT. Generalized regression modeling was then used to develop equations for the estimation of peak Vo(2) for the 6MWT. Additional variables included in the model were diffusing capacity of lung for carbon dioxide, FVC, maximal inspiratory pressure, weight (in kilograms), and age, with their appropriate interactions. This derived regression model accounted for 79% on the variance for estimation of peak Vo(2) in the patients studied. CONCLUSION: Peak Vo(2) can be estimated for men and for women by using the generalized equations presented. The calculation of 6M(WORK) is an improvement over distance ambulated as the 6MWT outcome. These data build on the existing body of knowledge for the 6MWT and extend its application for patients with COPD. Knowledge of the peak Vo(2) can be used for patient assessment, serial monitoring, evaluating disability, and as a common index of function across modalities. The calculation of 6M(WORK) outperformed distance ambulated and is easily converted to other indices of caloric expenditure that are commonly used in the laboratory and clinical settings.

Aged↗
PubMed1976

Dynamics of the chest wall during speech production: function of the thorax, rib cage, diaphragm, and abdomen.

Anteroposterior diameters of the rib cage and abdomen and esophageal and gastric pressures were measured in normal subjects in upright and supine body positions during respiratory maneuvers and utterance tasks. Data were charted in relative motion diagrams and various motion-pressure diagrams which enabled graphic solution for muscular pressures exerted by the chest wall and individually by the thorax, rib cage, diaphragm, and abdomen during utterances. Behaviors of the chest wall and its parts were found to depend upon lung volume, utterance loudness, body position, and utterance task. For utterances encompassing most of the vital capacity, chest wall effort was at first net inspiratory and later net expiratory. The former was governed predominately by the rib cage and the abdomen in the upright body position and by the diaphragm in the supine position. For conversational speech, chest wall effort was continuously expiratory, control being vested in the rib cage and the abdomen in the upright body position and typically in the rib cage alone in the supine position. Mechanisms operating during the utterances are discussed, particularly those involved with conversational speech production. We conclude that the abdomen occupies an especially important role in running conversational speech in that it mechanically tunes the diaphragm to increase the latter's inspiratory efficiency and thus enables man to minimally interrupt his ongoing speech for needed inspiratory pauses. We also discuss the relevance of our findings to clinical endeavors.

Abdomen↗
PubMed1999

Conditions for laryngeal mask insertion. A comparison of propofol versus sevoflurane with or without alfentanil.

One hundred unpremedicated ASA 1 or 2 patients scheduled for elective surgery were divided equally into four groups and recruited into this prospective, randomised parallel groups study. Induction was with propofol 2.5 mg.kg-1 or vital-capacity breath induction with sevoflurane (> 7% in the inspiratory gas) in 65% nitrous oxide and oxygen, or gaseous induction with sevoflurane plus alfentanil 5 micrograms.kg-1 or propofol 2.5 mg.kg-1 and alfentanil 5 micrograms.kg-1. The conditions for laryngeal mask insertion were assessed and graded on a three-point scale using six variables. The overall condition for laryngeal mask insertion was assessed as excellent, satisfactory or poor on the basis of total score in each group. Excellent or satisfactory conditions were observed in 25 (100%) patients in the sevoflurane-alfentanil group, 22 (88%) in the propofol-alfentanil group and 16 (64%) patients each in the propofol and sevoflurane groups (p < 0.001). A sevoflurane-alfentanil combination provides better conditions for laryngeal mask insertion when compared with sevoflurane alone, or a propofol-alfentanil combination.

Adolescent↗
PubMed2003

The effects of prior cycling and a successive run on respiratory muscle performance in triathletes.

The aim of the present study was to compare the effects of prior cycling and a successive run on respiratory muscle performance during a cycle-run succession as performed in the triathlon. We hypothesized that despite the moderate intensity of exercise and the absence of exhaustion, the crouched cycling position would induce a decrease in respiratory muscle performance that would be reversed by the successive vertical run position. Ten male triathletes (22.6 +/- 1.1 yr) performed a four-trial protocol: (1) an incremental cycle test to assess maximal oxygen uptake (VO2max), (2) 20 min of cycling (C), (3) 20 min of running (R), and (4) 20 min of cycling followed by 20 min of running (C-R). Trials 2, 3 and 4 were performed at the same metabolic intensity, i. e., 75 % of VO2max. Respiratory muscle force was assessed by measuring maximal expiratory (P(Emax)) and inspiratory (P(Imax)) pressures from the functional residual capacity (FRC) before and 10 min after C, R, and C-R. Respiratory muscle endurance was assessed one day before and 30 min after C, R, and C-R, by measuring the time limit (T(lim)), which corresponds to the length of time a respiratory load can be sustained before the process of fatigue develops sufficiently to cause task failure. The results showed a similar significant decrease in P(Imax) (132.4 +/- 4.9 versus 125.7 +/- 5.6 cm H2O, p < 0.05) and T(lim) (5.22 +/- 0.28 versus 3.68 +/- 0.32 min, p < 0.05) post-C and post-C-R (133.7 +/- 4.0 versus 126.9 +/- 5.2 cm H2O, and 5.29 +/- 0.18 versus 3.49 +/- 0.41 min, respectively, p < 0.05) compared with the pre-trial values. In contrast, P(Imax) and T(lim) were not significantly decreased post-R (131.8 +/- 6.1 cm H2O versus 129.6 +/- 6.4 cm H2O, and 4.90 +/- 0.69 versus 4.40 +/- 0.56 min, respectively, p > 0.05). We concluded that moderate intensity exercise not performed to exhaustion induced a decrease in respiratory muscle performance. Moreover, the respiratory muscle fatigue induced by prior cycling was maintained, and neither reversed nor worsened, by the successive run.

Adaptation, Physiological↗
PubMed2000

Aerodynamic and acoustic parameters in CO2 laser posterior transverse cordotomy for bilateral vocal fold paralysis.

The aim of this prospective study was to analyse airway improvement and acoustic and aerodynamic parameters after CO2 laser posterior transverse cordotomy (LPTC) in bilateral vocal fold paralysis (BVFP). Four patients (2 males, 2 females) were recorded pre- and post-operatively at 1, 3, 6, 12 and 24 months. Forced inspiratory volume during the first second (FIV), vital capacity, peakflow, and forced expiratory volume during the first second (FEV) were measured with the Gould II spirometer. Acoustic frequency features (average fundamental frequency, standard deviation, jitter, shimmer and harmonic-to-noise ratio) and speech duration parameters (maximum phonation time, number of words read per minute, and number of words per breath) were measured. Aerodynamic parameters were measured with the Aerophone II. Three tasks were completed. Pneumo-phonatory parameters in "maximum sustained phonation" and in "comfortable phonation", and laryngeal aerodynamic parameters (intraoral air pressure, oral airflow and sound pressure level) were measured non-invasively. Glottal resistance and vocal efficiency were calculated. FIV increased significantly after LPTC (p = 0.01). Postoperatively, frequency features were undetectable by standard commercialized algorithms. Acoustic and aerodynamic parameters improved in the measures obtained at the 6th postoperative month. These results were stable 2 years postoperatively in all cases. We conclude that laryngeal aerodynamic parameters can be used objectively to follow patients longitudinally after LPTC.

Aged↗
PubMed1988

Pleural pressure between diaphragm and rib cage during inspiratory muscle activity.

We measured the changes in pleural surface pressure (delta Ppl) in the area of apposition of the rib cage to the diaphragm (Aap) in anesthetized dogs during spontaneous breathing, inspiratory efforts after airway occlusion at functional residual capacity, and phrenic stimulation. Intact dogs were in supine or lateral posture; partially eviscerated dogs were in lateral posture. delta Ppl,ap often differed significantly from changes in abdominal pressure (delta Pab); sometimes they differed in sign (except during phrenic stimulation). Changes in transdiaphragmatic pressure in Aap (delta Pdi,ap) could be positive or negative and were less in eviscerated than in intact dogs. delta Pdi,ap could differ in sign among respiratory maneuvers and over different parts of Aap. Hence average delta Pdi,ap should be closer to zero than delta Pdi,ap at a given site. Since delta Ppl,ap = delta Prc,ap, where Prc,ap represents rib cage pressure in Aap, delta Pdi,ap = delta Pab - delta Prc,ap. Hence, considering that delta Pab and delta Prc depend on different factors, delta Pdi,ap may differ from zero. This pressure difference seems related to the interaction between two semisolid structures (contracted diaphragm and rib cage in Aap) constrained to the same shape and position.

Animals↗
PubMedDate not supplied

Inhaled drug delivery: a practical guide to prescribing inhaler devices.

Direct delivery of medication to the target organ results in a high ratio of local to systemic bioavailability and has made aerosol delivery of respiratory medication the route of choice for the treatment of obstructive lung diseases. The most commonly prescribed device is the pressurized metered dose inhaler (pMDI); its major drawback is the requirement that inspiration and actuation of the device be well coordinated. Other requirements for effective drug delivery include an optimal inspiratory flow, a full inspiration from functional residual capacity and a breath hold of at least 6 s. Available pMDIs are to be gradually phased out due to their use of atmospheric ozone-depleting chlorofluorocarbons (CFCs) as propellants. Newer pMDI devices using non-CFC propellants are available; preliminary experience suggests these devices greatly increase systemic bioavailability of inhaled corticosteroids. The newer multidose dry powder inhalation devices (DPIs) are breath actuated, thus facilitating coordination with inspiration, and contain fewer ingredients. Furthermore, drug delivery is adequate even at low inspired flows, making their use appropriate in almost all situations. Equivalence of dosing among different devices for inhaled corticosteroids will remain imprecise, requiring the physician to adjust the dose of medication to the lowest dose that provides adequate control of asthma. Asthma education will be needed to instruct patients on the effective use of the numerous inhalation devices available.

Anti-Asthmatic Agents↗
PubMed2000

Hard metal alveolitis accompanied by rheumatoid arthritis.

Hard metal lung diseases (HML) are rare, and complex to diagnose. We describe the case of a patient with allergic alveolitis accompanied by rheumatoid arthritis. A sharpener of hard metal by trade, our patient was a 45-year-old, nonsmoking Caucasian female who experienced symptoms of cough and phlegm, and dyspnea on exertion. Preliminary lung findings were inspiratory rales in both basal areas, decreased diffusion capacity and a radiological picture resembling sarcoidosis. A high-resolution computed tomography scan indicated patchy alveolitis as well. An open lung biopsy revealed non-necrotizing granulomas consisting of epitheloid cells and surrounded by lymphocytes, plasma cells and a few eosinophils. These cells also occupied the thickened alveolar interstitium. Macrophages in the alveolar spaces, some of them multinuclear, contained dust particles. Hard metal alveolitis is clinically well known and, in this patient, has been described histologically. After the patient had quit working with hard metal and following corticosteroid therapy, pulmonary symptoms and signs were relieved. During this recovery period, however, she contracted rheumatoid arthritis.

Alloys↗
PubMed2004

Dyspnoea at rest and at the end of different exercises in patients with near-fatal asthma.

Blunted perception of dyspnoea under resistive loading has been observed in patients with a history of near-fatal asthma (NFA). The perception of dyspnoea at rest and at the end point of various exercises was assessed in such patients. Respiratory function and exercise capacity (6-min walking distance, incremental cycloergometry and inspiratory threshold loading) were assessed in seven NFA and eight non-NFA patients. Dyspnoea (Borg scale) was measured at rest and at the end point of the various exercises. Dyspnoea at rest was significantly lower in NFA patients. Although exercise tolerance was similarly reduced in both the NFA and non-NFA groups, dyspnoea at peak cycle exercise was significantly lower in the former (2.6+/-2 versus 6.1+/-3.8 (Borg scale; mean+/-SD)), who mainly (86%) stopped because of leg discomfort. A similar trend was observed in the 6-min walking distance and inspiratory threshold loading tests. Dyspnoea at peak exercise was the best indicator of the NFA condition, with a sensitivity of 100% and specificity of 63% for a Borg scale score of < or = 6. Perception of dyspnoea is blunted in near-fatal asthma patients at both rest and the end point of various forms of exercise. Dyspnoea at peak exercise is the best indicator of the near-fatal asthma condition.

Adolescent↗
PubMed1998

Acute oxygen supplementation does not relieve the impairment of respiratory muscle strength in hypoxemic COPD.

STUDY OBJECTIVES: To verify whether hypoxemia affects respiratory muscle strength in the absence of malnutrition and whether such effect, if present, is reversible with an acute oxygen supplementation. DESIGN: Case series analysis, before-after trial. SETTING: Outpatient pneumology departments of two university hospitals. PATIENTS: One hundred twenty patients affected by COPD in stable conditions having actual to ideal body weight ratio of > or =90%. MEASUREMENTS AND RESULTS: Maximal inspiratory pressure (MIP) was measured at functional residual capacity level in the whole sample of subjects and during oxygen supplementation in 58 patients having a PaO2< or =60 mm Hg when breathing in room air. Predictors of MIP were assessed by a multivariate analysis. MIP values before and after oxygen supplementation were compared by a paired t test. MIP was independently correlated with FVC (p<0.001), PaO2 (p<0.01), and age (p<0.01). In the subgroup of hypoxemic patients, MIP values did not change significantly after oxygen supplementation (3.08+/-1.74 vs 3.03+/-1.91 kPa, t=0.43, not significant). CONCLUSIONS: Hypoxemia is an important negative correlate of MIP even in well-nourished COPD patients. Its effect is not reversible with an acute oxygen supplementation.

Age Factors↗
PubMed2003

An automated approach to quantitative air trapping measurements in mild cystic fibrosis.

PURPOSE: To automatically derive the degree of air trapping in mild cystic fibrosis (CF) disease from high-resolution CT (HRCT) data, and to evaluate the discriminating power of the measurement. MATERIALS AND METHODS: The data consist of six pairs of anatomically matched tomographic slices, obtained during breath-holding in triggered HRCT acquisitions. The pairs consist of an inspiratory slice, at > or = 95% of slow vital capacity, and an expiratory slice at near residual volume (nRV). The subjects are 25 patients with mild CF and 10 age-matched, normal control subjects. SUBJECTS: Lung segmentation is automatic. The limits defining air trapping in the expiratory slices are determined by the distribution of densities in the expanded lung. They are modulated by density changes between expiration and inspiration. Air trapping defects consist of contiguous low-density voxels. The difference between patients and control subjects was evaluated in comparison to pulmonary function test (PFT) results and lung density distribution descriptors (global density descriptors). RESULTS: In mild CF, air trapping does not correlate with global PFT results, except for the ratio of residual volume (RV) to total lung capacity (TLC); however, the size of air trapping defects was the best discriminator between patients and control subjects (p < 0.005). Of PFT results, only RV/TLC reached significance at p < 0.05. The global density descriptors reached near significance in the nRV images only. CONCLUSION: Air trapping defined as defect size and measured in an objective automated manner is a powerful discriminator for mild CF.

Adolescent↗
PubMed2001

[Physiopathology of chronic respiratory insufficiency].

The host of chronic respiratory abnormalities responsible for an abnormal hematosis or for a handicap can be termed generically as chronic respiratory insufficiency. Hypoxemia can be the consequence of perturbations of oxygen transfer (fibrosis), of abnormal ventilation-perfusion ratios (venous admixture, chronic obstructive pulmonary disease [COPD]), or of hypoventilation (neuromuscular diseases). Hypercapnia can stem from hypoventilation (neuromuscular diseases), or from abnormal ventilation-perfusion ratios (dead space effect) (COPD). An imbalance between the capacity of the respiratory muscle to produce negative inspiratory pressures and the load they are faced with is a source of hypercapnia, and of dyspnoea and handicap independently of hematosis (COPD, neuromuscular diseases). The effects of hypoxemia on cellular functions make chronic respiratory insufficiency a systemic disease.

Chronic Disease↗
PubMed2006

[Physiopathology of respiratory muscles].

Different factors can have deleterious effect the inspiratory muscles: increased intrinsic mechanical loading of the inspiratory muscles, functional inspiratory muscle weakness, increased ventilatory demand related to capacity... These muscle changes influence exercise tolerance and contribute to dyspnea.

Dyspnea↗
PubMedDate not supplied

Pulmonary functions in air conditioner users.

Air conditioning may affect human health since it has profound effect on our environment, than just lowering temperature. The present study was planned to assess the effect of air conditioners (AC) on pulmonary functions in young healthy non-smoker males. The study group comprised of ten subjects who were using AC's in their cars for at least 1 hr daily since last 6 months. While ten subjects who did not use AC at all served as controls. The pulmonary functions were assessed using PK Morgan 232 spirometer in a closed room. The peak expiratory flow rate (PEFR) and Forced expiratory flow between 25-75% of vital capacity (FEF25-75) were significantly reduced in subjects using car AC's. Inspiratory flow rates also showed a trend towards decline in AC users but could not reach the level of significance. The lung volumes and capacities were not significantly different in the two groups except for forced expiratory volume in 0.5 sec (FEV 0.5 sec), which also decreased in AC users. The airway resistance and lung compliance did not show significant change. In the presence of normal FEV1, reduced FEF25-75% which is the flow rate over the middle half of vital capacity, is an evidence of mild airflow limitation. The result is suggestive of predisposition of AC users towards respiratory disorders in form of mild airflow restriction.

Adolescent↗
PubMed1990

Respiratory muscle insufficiency in acute respiratory failure of subjects with severe COPD: treatment with intermittent negative pressure ventilation.

Nine subjects with severe chronic obstructive pulmonary disease (COPD) in acute respiratory failure (ARF) and with marked weakness of the respiratory muscles (Group A) underwent intermittent negative pressure ventilation by means of an iron lung (8 h daily for 7 days). Seven subjects with COPD in stabilized chronic respiratory failure (Group B) were studied as controls and submitted to the same medical therapy without ventilator treatment. Functional respiratory tests were performed before and after 7 days of treatment. After ventilatory treatment, Group A showed an increase of maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), vital capacity (VC), arterial oxygen tension (PaO2), pH and a decrease of residual volume (RV), total lung capacity of (TLC) and arterial carbon dioxide tension (PaCO2) (all statistically significant). No improvement was ascertained in the functional parameters of Group B. The expiratory muscles seem to play a determining role in ARF. We conclude that the iron lung is a useful therapeutic defence in removing muscular fatigue and in restoring a good level of respiratory compensation of ARF in severe COPD.

Female↗
PubMed1994

[Effect of nasal CPAP on human diaphragm position and lung volume].

The cephalic margin of the zone of apposition (ZOA) was observed with ultrasonography at ambient pressure and during nasal continuous positive airway pressure (nasal CPAP) in nine awake healthy males in a supine position. In a relaxed state at ambient pressure, there was a significant (p < 0.001) linear relationship between lung volume and the movement of the cephalic margin of the ZOA over the range from maximum expiratory position (MEP) to maximum inspiratory position (MIP). With nasal CPAP, functional residual capacity increased significantly (p < 0.01) in proportion to the increase in CPAP. At 20 cmH2O CPAP, the mean increase in volume at end expiration was 36% of the vital capacity measured at ambient pressure. The cephalic margin of the ZOA moved significantly (p < 0.01) in a caudal direction as CPAP was increased. At 20 cmH2O CPAP, the cephalic margin of the ZOA at end expiratory position (EEP) had moved 55% of the difference from MIP to MEP measured at ambient pressure. The end expiratory diaphragm position during nasal CPAP was lower than the diaphragm position at ambient pressure when lung volumes were equal. These results suggest that during nasal CPAP the chest wall is distorted from its relaxed configuration, with a decrease in rib cage expansion and an increase in outward displacement of the abdominal wall.

Diaphragm↗
PubMed1993

An easy method of spirometry.

Recording of forced expiration from tidal inspiratory level-referred to as Forced Expiratory Capacity (FEC) is a simple and more convenient technique than the conventional forced vital capacity (FVC) manouvre. From FEC tracing, volume expelled in one second (FEC1) and its percentage (FEC1%) can be measured. Such spirometric recording obtained from tidal breathing to Residual Volume (RV) may be referred to as Spirometric Recording at low lung volume. Asthmatics as well as old subjects find this manouvre easier to perform than the conventional FVC technique. FEC recording becomes a simple, reliable and sensitive test for evaluation of early airway obstruction in asymptomatic smokers and therefore may be utilised in clinical and epidemiologic surveys.

Adolescent↗
PubMed1993

Factors contributing to dyspnoea during bronchoconstriction and exercise in asthmatic subjects.

The purpose of the present study was to identify: 1) whether dyspnoea during bronchoconstriction and exercise is related, in asthmatic subjects; and 2) to what extent baseline pulmonary function and respiratory muscle strength contribute to dyspnoea under both conditions. One hundred and seventy five consecutive subjects, referred with suspected asthma, rated the intensity of dyspnoea (Borg scale 0-10): 1) during the administration of doubling concentrations of methacholine to 32 mg.ml-1 methacholine, or until the baseline forced expiratory volume in one second (FEV1) was reduced by 20%; and 2) during incremental cycle ergometry (100 kpm.min-1 each minute) to maximal capacity. 138/175 subjects achieved a 20% reduction in their baseline FEV1; 18 of the 138 were excluded, 2 children and 16 with complicating pulmonary disorders (diffusing capacity of the lung for carbon monoxide (DLCO) and/or total lung capacity (TLC) < 70% predicted). The remaining 120 out of 175 constituted the study population. Dyspnoea following a 20% reduction in the baseline FEV1 (Dys20%) was linearly interpolated, using the rating of dyspnoea and the FEV1 at the two final concentrations of methacholine. In the 120 asthmatic subjects, the mean intensity of dyspnoea was "moderate" (2.9, SD 1.91; Borg 0-10) and the intensity across subjects was not significantly related to baseline FEV1, vital capacity (VC), FEV1/VC, DLCO, TLC and maximal static inspiratory pressure (MIP), alone or in combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗