Biomedical subjects

H T Folgering

Publications and source records attributed to H T Folgering.

At least 37 records · Page 2Linked to original sources

PubMed1999

Induction of acute metabolic acid/base changes in humans.

The aim of this study was to induce acute metabolic acid/base changes of > or = 2 mequiv.l-1 change in base excess (BE) to aid future investigations of respiratory parameters under these conditions. Ammonium chloride (NH4Cl) was administered to induce acidification and furosemide was used to induce alkalization. Nine healthy volunteers (six men and three women aged 35 +/- 18 years) ingested a calculated amount of NH4Cl at t = 0 and a repeat dose after 60 min. Eight healthy volunteers (three men and five women aged 37 +/- 16 years) consumed 40 mg of furosemide. Arterialized capillary blood gases were measured at t = 0, 30, 60, 90, 120 and 180 min. In the case of acute metabolic acidosis, the target acidification of 2 mequiv.l-1 was attained after 30 min and the greatest change was achieved at 90 min: -4.9 (2.2) mequiv.l-1. In the case of acute metabolic alkalosis, the target alkalization of 2 mequiv.l-1 was reached between 120 and 180 min and the greatest change was seen at 180 min: +2.2 (1.4) mequiv.l-1. Significant (P < 0.05) changes in acidification compared with baseline BE values were found between 60 and 180 min; significant (P < 0.05) changes in alkalization were found between 120 and 150 min. PaCO2 did not change significantly in either condition. We conclude that NH4Cl and furosemide induce a steady state of pure metabolic acid/base conditions in humans, which is buffered in an isocapnic manner.

Acid-Base Equilibrium↗

PubMed1999

Relation of the perception of airway obstruction to the severity of asthma.

BACKGROUND: Patients with a poor perception of their symptoms of asthma seem to have an increased risk of an asthma attack. The influence of factors such as airway calibre, bronchial hyperresponsiveness, age and sex on the "perceptiveness" of a patient are poorly understood. It is of clinical importance to identify patients who are likely to have a poor perception of their symptoms. We have studied the perception of bronchoconstriction by asthmatic patients during a histamine provocation test and analysed the influence of bronchial obstruction, hyperresponsiveness, sex, and age. We were particularly interested to establish whether there was any difference in perception between subjects with a greater or lesser severity of asthma (expressed as bronchial obstruction, hyperresponsiveness). METHODS: One hundred and thirty four patients with allergic asthma underwent a histamine provocation test. The FEV1 was measured after each inhalation of histamine. Subjects were asked to rate subjective quantification of the sensation of breathlessness on a visual analogue scale (VAS). The relationship between changes in VAS values and the reduction in FEV1 as a percentage of the baseline value was analysed by determining the linear regression slope (alpha) between the two parameters and indicates the perception of airway obstruction. Multiple regression analysis was performed to investigate the effect of baseline FEV1, bronchial hyperresponsiveness, sex and age on the "perceptiveness" for bronchoconstriction. RESULTS: The median value of the slope alpha (indicating the perception of airway obstruction) was 0.91 (25-75th percentile: 0.48-1.45). Age and sex had no influence on the perception of bronchoconstriction. Both initial bronchial tone (baseline FEV1) and bronchial hyperresponsiveness (PC20) showed a significant correlation with the perception of bronchoconstriction. The regression coefficients for FEV1 and 2log PC20 in the multiple regression model were 0.20 and 0.10. Patients who had a low baseline FEV1 and/or a high bronchial responsiveness to histamine were more likely to show a low perceptiveness for bronchoconstriction during the challenge test. CONCLUSIONS: Low baseline FEV1 and high bronchial responsiveness are associated with a low degree of "perceptiveness" for bronchoconstriction. This suggests that patients with a more severe degree of asthma either show adaptation of "perceptiveness" for airway obstruction or that low perceptiveness leads to more severe asthma.

Adolescent↗

PubMed1999

Xanthine oxidase is involved in exercise-induced oxidative stress in chronic obstructive pulmonary disease.

In the present study, we hypothesized that exhaustive exercise in patients with chronic obstructive pulmonary disease (COPD) results in glutathione oxidation and lipid peroxidation and that xanthine oxidase (XO) contributes to free radical generation during exercise. COPD patients performed incremental cycle ergometry until exhaustion with (n = 8) or without (n = 8) prior treatment with allopurinol, an XO inhibitor. Reduced (GSH) and oxidized glutathione (GSSG) and lipid peroxides [malondialdehyde (MDA)] were measured in arterial blood. In nontreated COPD patients, maximal exercise (approximately 75 W) resulted in a significant increase in the GSSG-to-GSH ratio (4. 6 +/- 0.9% at rest vs. 9.3 +/- 1.7% after exercise). In nontreated patients, MDA increased from 0.68 +/- 0.08 nmol/ml at rest up to 1. 32 +/- 0.13 nmol/ml 60 min after cessation of exercise. In contrast, in patients treated with allopurinol, GSSG-to-GSH ratio did not increase in response to exercise (5.0 +/- 1.2% preexercise vs. 4.6 +/- 1.1% after exercise). Plasma lipid peroxide formation was also inhibited by allopurinol pretreatment (0.72 +/- 0.15 nmol/ml preexercise vs. 0.64 +/- 0.09 nmol/ml 60 min after exercise). We conclude that strenuous exercise in COPD patients results in blood glutathione oxidation and lipid peroxidation. This can be inhibited by treatment with allopurinol, indicating that XO is an important source for free radical generation during exercise in COPD.

Adenosine Triphosphate↗

PubMed1999

Perception of bronchoconstriction in asthma patients measured during histamine challenge test.

This study investigated two aspects of the perception of bronchoconstriction ("sensitivity" and "absolute perceptual magnitude") in asthmatic patients and identified which clinical characteristics are related to these two aspects of perception of bronchoconstriction. The perception of histamine induced bronchoconstriction was measured in 128 asthmatic patients. Subjects quantified their breathlessness on a Visual Analogue Scale (VAS) before forced expiratory volume in one second (FEV1 was measured after each inhalation of histamine. The perceptive "sensitivity" for changes in FEV1 was analysed by the "VAS percentage fall in FEV1" slope. The "absolute perceptual magnitude" was determined by the VAS value at a 20% fall in FEV1. Spearman correlations were used for analysis between the two aspects of perception and asthma symptoms, peak flow variability, bronchial responsiveness and FEV1 % predicted. Patients with a low "sensitivity" for changes in FEV1 were more likely to show a frequent peak flow variability (Rs=-0.21; p<0.05), a high bronchial responsiveness (Rs= 0.37; p<0.001) and a low baseline FEV1 % pred (Rs=0.22; p<0.05). Patient's "absolute perceptual magnitude" correlated positively with symptoms during daily life (significant correlations varied 0.21-0.32) but not with the lung function parameters. The severity of asthma reflected by a low lung function and a high bronchial responsiveness, is associated with a low "sensitivity" for changes in forced expiratory volume in one second. A patient's "absolute perceptual magnitude" is positively related with asthma symptoms during daily life.

Adult↗

PubMed1998

Cardio-respiratory load of exercise training in patients with severe COPD.

The effect of physical training depends on the intensity at which exercise is performed. Patients with chronic obstructive pulmonary disease (COPD) may not tolerate high exercise intensities during training due to breathlessness. The purpose of the present study was to investigate the cardiorespiratory load of exercise training, during pulmonary rehabilitation, in patients with severe COPD. We also studied the effects of pulmonary rehabilitation on maximum exercise performance. Thirteen patients with stable COPD (FEV1 (S.D.) 1.0 (0.3) L) performed an incremental cycle exercise test at baseline and after a 10 week in-patient pulmonary rehabilitation programme. Exercise training consisted of dynamic and isometric strength training exercises, and training of specific daily life activities. Training sessions were held 5 days per week for 10 weeks. Heart rate (HR) and dyspnoea ratings (Borg scale) were measured during one session in the second or third week of training, and were compared with values obtained during incremental cycle exercise at baseline. The ventilatory load during the training was estimated by using the relationship between HR and minute ventilation (VE) during incremental cycle exercise at baseline. The duration of a training session was 80 (7) min, including periods of rest. The HR during various exercises of the training programme varied between 94 (17) and 103 (14)% of peak HR during incremental cycle exercise. Borg scores during the training varied between 2.0 and 5.7, and were lower than the Borg score at peak exercise (6.5 (2.0)). HR was more than 90% of peak HR during 36 (33) min of the whole training session, which corresponded with a VE of 81 (11)% of peak VE during incremental cycle exercise. Training significantly increased maximum work load (Wmax) from 62 (25) to 73 (21) W (P < 0.05), without any change in peak HR, VE and VO2. In patients with severe COPD, the training intensity in terms of cardio-respiratory load was high in relation to individual maximum values. Pulmonary rehabilitation, including exercise training, improved maximum exercise performance.

Aged↗

PubMed1998

Exertional dyspnoea in patients with airway obstruction, with and without CO2 retention.

BACKGROUND: Dyspnoea is a common and disabling symptom in patients with cardiopulmonary disease. Unfortunately the mechanisms that produce dyspnoea are still poorly understood. The relationship between dyspnoea and the load on the ventilatory muscles, chemical drive, and ventilatory indices was therefore assessed in patients with obstructive pulmonary disease during an incremental exercise test. METHODS: Fifty patients with a wide range of obstructive pulmonary disease (mean forced expiratory volume in one second (FEV1) 66.1 (28.8)% predicted) performed an incremental cycle ergometer test. A subdivision was made between subjects with CO2 retention (delta PaCO2 > or = 0, n = 22) and subjects without CO2 retention (delta PaCO2 < 0, n = 28) during exercise. During the test dyspnoea (Borg score), oesophageal pressures (mechanical load on the ventilatory muscles (time tension index (TTI), blood gas tensions, and minute ventilation were measured. Correlations for changes in mechanical and chemical factors with changes in dyspnoea score were calculated to assess relevant factors. An analysis of covariance was used to examine whether there was a relationship between dyspnoea score and each of these factors and whether this relationship was different between the subgroups with and without CO2 retention. Multiple regression analysis was used to assess the independent effect of each parameter on dyspnoea sensation. Furthermore, the amplitude of pleural pressure swing ((Pi + Pe)act) generated at maximal work load (Ptot, an indication of the load on all respiratory muscles) was calculated. Analysis of covariance was used to assess whether there was a relationship between tidal volume (VT) and Ptot and whether this relationship was different between the groups (slopes are an expression of the length-tension inappropriateness, LTI). RESULTS: In the total group and the group without CO2 retention a significant correlation between dyspnoea and the increase in the inspiratory time tension index (TTIi) was present. In the group with CO2 retention a significant correlation was seen between dyspnoea and delta PaCO2. The factors delta PaO2, delta VE%MVV and delta (VT/Ti) showed a correlation with a p value of < or = 0.10 both in the total group and in those without CO2 retention. In an analysis of covariance the relationship between dyspnoea score and delta PaCO2 appeared to be significantly different between the two subgroups, being more pronounced in the group with CO2 retention. No other relationships with change in dyspnoea score were found. There was no significant relationship between VT and Ptot in the total group nor in the two subgroups, indicating some length-tension inappropriateness in both groups. CONCLUSIONS: In patients with distinctive pulmonary disease who are normocapnic or hypocapnic the mechanical load (delta TTIi) and length-tension inappropriateness (LTI) on ventilatory muscles seem to be the main determinant of exertional dyspnoea. As soon as hypercapnia occurs, this seems to override all other inputs for dyspnoea.

Analysis of Variance↗

PubMed1998

Anabolic steroids in part reverse glucocorticoid-induced alterations in rat diaphragm.

Animal and clinical studies have shown respiratory muscle dysfunction caused by treatment with glucocorticoids. The present study was designed to investigate whether anabolic steroids are able to antagonize the loss of diaphragm force induced by long-term low-dose methylprednisolone (MP) administration. Male adult rats were randomized to receive saline or MP (0.2 mg . kg-1 .day-1 sc) during 9 mo, with or without nandrolone decanoate (ND; 1 mg . kg-1 . wm -1 im) during the last 3 mo. The approximately 10% reduction in force generation of isolated diaphragm bundles induced by MP was completely abolished by addition of ND. The MP-induced decrease in number of fibers expressing type IIb myosin heavy chains was not reversed by ND. MP slightly reduced type I, IIa, and IIx fiber cross-sectional areas (CSA), but not type IIb fiber CSA. Addition of ND abolished the reduction in IIa and IIx fiber CSA. The MP-induced alterations in glycogenolytic activity and fatty acid oxidation capacity were not reversed by ND. In conclusion, the marked reduction in diaphragm force caused by long-term low-dose MP was completely abolished by addition of ND. ND in part also antagonized the effects of MP on diaphragm morphology but showed no beneficial effects on biochemical changes.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1998

Long-term results after correction of anterior chest wall deformities.

BACKGROUND: Surgical correction of pectus deformities was mainly performed for cosmetic and psychologic reasons but eventual cardiopulmonary symptoms improved. Whether this results from alterations in cardiopulmonary physiology is still controversial METHODS: In 25 years 662 patients underwent correction (390 for pectus excavatum-funnel chest, 235 for pectus carinatum-chicken chest, 37 for pectus arcuatum-pouter pigeon chest). Surgical correction was mainly performed for cosmetic and psychologic reasons. Sternochondroplasty was performed without prosthetic material RESULTS: Clinical results for funnel chest were satisfactory in 83.6% (excellent 44.1%, good 39.5%) and were always good for protrusion deformities if enough deformed cartilages were resected. In a retrospective study the pulmonary function tests performed on 152 patients with funnel chest before surgery and at long-term follow-up demonstrated an eventual increased restriction at follow-up, despite symptomatic improvement and increased anteroposterior chest diameter on the X-ray, but restricted anterior chest wall motion. In a prospective study the exercise cardiorespiratory function tests on 35 patients with funnel chest before and one year after operation suggested unchanged work performance, but an increased oxygen consumption and acidification due to a higher work of breathing after operation, caused by decreased chest wall compliance. CONCLUSIONS: The subjective physical improvement after operation cannot be explained by changes in static lung volumes or in cardiorespiratory function at exercise, but is due to other unexplained factors. Satisfactory subjective long-term results of most patients justify surgical correction. Both physical as well as psychologic and cosmetic factors may allow operative correction.

Adolescent↗

PubMed1997

Effects of long-term low-dose methylprednisolone on rat diaphragm function and structure.

In animal studies, high dosages of corticosteroids cause changes in diaphragm structure and function. The present study was designed to investigate the effects of long-term low-dose methylprednisolone (MP) administration on rat diaphragm contractile properties and morphology. Thirty adult rats were treated with saline or MP (0.2 mg/kg/day s.c.) during 6 months. Contractile properties of isolated diaphragm strips, immunohistochemical characteristics analyzed by means of antibodies reactive with myosin heavy chain isoforms, and enzyme activities were determined in the diaphragm muscle. MP significantly reduced diaphragm force generation by -15% over a wide range of stimulation frequencies. The number of type IIb fibers was reduced by MP. There was a mild but significant decrease in type I and IIa fiber cross-sectional area (CSA), whereas type IIx and IIb CSA did not change. These changes resulted in a reduction in the relative contribution of type IIb fibers to total diaphragm muscle area. Biochemically, MP decreased glycogenolytic activity, while fatty acid oxidation and oxidative capacity were increased. In conclusion, long-term low-dose MP administration caused a marked impairment in diaphragm function. This is accompanied by changes in diaphragm muscle morphology and enzyme capacity.

Animals↗

PubMed1997

Ventilatory response to positive and negative work in patients with chronic obstructive pulmonary disease.

In healthy subjects, oxygen consumption and cardiorespiratory responses are lower during eccentric exercise (negative work, Wneg) than during concentric exercise (positive work, Wpos) at the same work load. The aim of the present study was to investigate the ventilatory response to Wneg in patients with chronic obstructive pulmonary disease (COPD). The study population consisted of 12 subjects with COPD [forced expiratory volume in 1 s (FEV1) mean (SD): 1.5 (0.4) 1, 46 (16)% of predicted]. Concentric and eccentric exercise tests (6 min exercise; interval > or = 1 h) were performed in random order at constant work loads of 25 and 50% of the individual maximal (positive) work capacity. Expired ventilation per minute (VE), oxygen consumption (VO2) and carbon dioxide production (VCO2) were 30% lower during Wneg than during Wpos for both work intensities. The breathing reserve during 25% Wneg was 11 (8)% and during 50% Wneg was 18 (14)% higher than during Wpos at corresponding work loads (P < 0.01). VE/VO2 and VE/VCO2 were similar during Wpos and Wneg. Arterial carbon dioxide tension (PaCO2) increased by 0.1 (0.4) kPa during 50% Wneg and by 0.7 (0.5) kPa during 50% Wpos (P < 0.01). During 50% Wneg' perceived leg effort (modified Borg scale) tended to be higher than perceived breathlessness (2.4 (1.2) vs. 2.0 (1.1). It was concluded that in subjects with COPD, the ventilatory requirements of Wneg were considerably lower than those of Wpos at similar work loads up to 50% of maximal work capacity. During Wneg, the ventilatory reserve was higher and gas exchange was less disturbed as a result of a lower VO2 and VCO2.

Carbon Dioxide↗

PubMed1997

Respiratory muscle strength and endurance in individuals with tetraplegia.

The purpose of this study was to assess the strength and endurance capacity of the respiratory muscles in individuals with tetraplegia and to compare these properties to those in able-bodied subjects. In addition, the relationship between respiratory muscle properties and respiratory function, ie, ventilation and gas exchange, was examined. Fifteen individuals with tetraplegia (TP) and 15 able-bodied controls (AB) participated in this study. Respiratory muscle strength was assessed by measuring static inspiratory (Pi-max) and expiratory (Pe-max) mouth pressure, whereas inspiratory endurance capacity (Pendu) was determined using an incremental ventilatory threshold loading test. Results were significantly lower in TP compared to AB: Pi-max (5.9 vs 8.4 kPa), Pre-max (5.6 vs 12.3 kPa), Pendu (2.7 vs 6.9 kPa), vital capacity (3.1 vs 5.5 l) and rest oxygen uptake (0.21 vs 0.29 ml/min) and significant correlations were found between the respiratory muscle properties and the respiratory function. Of note is the fact that the ratio Pendu/Pi-max was significantly lower in TP (0.49) compared to AB (0.82). This implies that the capacity to generate pressure during the endurance test was not fully used in TP, probably due to an early onset of muscle fatigue and an altered force-length relationship of the diaphragm muscle. Results of this study demonstrate a limited ability in individuals with tetraplegia to ventilate.

Adult↗

PubMed1997

Potassium and ventilation during positive and negative work in patients with chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD), reduced ventilatory reserves limit exercise tolerance. In these patients, the ventilatory requirements of eccentric exercise (negative work, Wneg) are lower than those of concentric exercise (positive work, Wpos) at similar workloads. In this study, we investigated the relationship between plasma potassium levels and ventilation during Wpos and Wneg in these patients. Twelve patients with stable COPD [mean (SD) FEV1 46% (16) of predicted] performed Wpos and Wneg on a cycle ergometer (6 min of exercise; interval > or = 1 h) in a randomized order at a constant workload of 50% of the individual maximum (positive) work capacity. Minute ventilation (VE) and arterial plasma potassium concentration ([K+]a) were measured at rest, and at 1-min intervals during exercise and during 3 min of recovery. VE increased less during Wneg than during Wpos [6 (range 3-26) vs. 18 (range 8-28) 1 min-1; P < 0.01]. VE during Wneg was reduced in proportion to VCO2. The increase in [K+]a during Wpos and Wneg [0.45 (range 0.26-0.75) and 0.34 (range 0.1-0.97) mM] did not differ significantly. VE was closely correlated with VCO2 during both types of exercise. VE was also closely correlated with [K+]a, but the slope of the relationship between [K+]a and VE was steeper during Wpos than during Wneg [39.1 (range 15.2-88.6) vs. 18.3 (range 7.2-37.3) 1 min-1 mM-1; P = 0.012]. In contrast, the slope of the relationship between VCO2 and VE was similar during both types of exercise [27.8 (range 19.2-37.1) vs. 32.1 (range 19.8-48.4)]. Thus, for a given increase in [K+]a, the increase in VE was significantly less during Wneg. In patients with COPD, potassium did not explain the difference in exercise ventilation between Wneg and Wpos, and may not play a significant role in the control of breathing during low-intensity exercise.

Adult↗

PubMed1997

Mini-Wright peak flow meters are reliable after 5 years use. Dutch CNSLD Study Group.

In studies with a long-term follow-up, peak expiratory flow (PEF) meters are often used to assess bronchial obstruction. The question arises whether data obtained with these frequently used meters are still reliable after several years of use, and whether the old meters should be renewed after a certain period. In the present study, we tested the reliability of PEF values measured with mini-Wright PEF meters that had been used frequently for 5 yrs. The values obtained with these meters were compared with values measured with identical but new meters, in 50 patients with obstructive airways disease. Though statistically significant, there was no clinically significant difference in mean PEF measured with the old and new meters in most patients (mean difference 10.2 L.min-1). However, on an individual basis, the differences between old and new meters could be large (upper and lower limits of agreement (mean +/- 2 SD) being 63.6 and -43.2 L.min-1, respectively). We conclude that mean peak expiratory flow values measured with frequently used mini-Wright peak expiratory flow meters are still reliable after 5 yrs. In long-term studies, renewal of peak expiratory flow meters should be restricted to cases of obvious malfunction.

Equipment Failure↗

PubMed1997

Breathing pattern during bronchial challenge in humans.

Increases in minute ventilation (V'E) have been observed during exacerbations of asthma and in response to administration of histamine. However, it is not yet clear how the breathing pattern is affected, and whether the increase in V'E is found in general. In the present study, the effects of inhalation of histamine on respiratory frequency (fR), tidal volume (VT), V'E, and on functional residual capacity (FRC) were evaluated in 63 humans. Forty four subjects were hyperresponsive (BHR+). In each of these subjects, the doses of histamine applied for the present study (mean 3.5 mg x mL(-1)) caused a decrease in forced expiratory volume in one second (FEV1) that was greater than 20% of the control value. The dose of histamine applied in the 19 nonhyperresponsive subjects (BHR-) was substantially larger (8.0 mg x mL(-1)) whilst for this dose the decrease in FEV1 was less than 20% of control value. After histamine, fR was significantly increased in both subgroups of subjects, BHR+ and BHR-. The increase in V'E was significant in BHR- but not significant in BHR+. In general, the changes in V'E,fR and VT were not uniform; comparable numbers of subjects responded with increases (n=33) and decreases (n=30) in V'E. For fR 40 subjects responded with an increase and 23 with a decrease, and for VT these numbers were 26 and 37, respectively. The increase in FRC after histamine was significantly larger in BHR+ subjects than in BHR-. These findings may be interpreted to indicate that different mechanisms with opposite effects may be operating simultaneously, e.g. excitation of central inspiratory activity by stimulation of rapidly-adapting pulmonary stretch receptors, which will promote increases in respiratory frequency, tidal volume and minute ventilation, and bronchoconstriction with increased airway resistance, which will promote decreases in these parameters. As a consequence, depending on the net result of these opposite contributions to, e.g. minute ventilation, administration of histamine will cause an increase in minute ventilation in one subject and a decrease in another.

Adult↗

PubMed1997

Training with supplemental oxygen in patients with COPD and hypoxaemia at peak exercise.

Supplemental oxygen has acute beneficial effects on exercise performance in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study was to investigate whether oxygen-supplemented training enhances the effects of training while breathing room air in patients with severe COPD. A randomized controlled trial was performed in 24 patients with severe COPD who developed hypoxaemia during incremental cycle exercise (arterial oxygen saturation (Sa,O2) <90% at peak exercise). All patients participated in an in-patient pulmonary rehabilitation programme of 10 weeks duration. They were assigned either to general exercise training while breathing room air (GET/RA group: forced expiratory volume in one second (FEV1) 38% of predicted; arterial oxygen tension (Pa,O2) 10.5 kPa at rest; Pa,O2 7.3 kPa at peak exercise), or to GET while breathing supplemental oxygen (GET/O2 group: FEV1 29% pred; Pa,O2 10.2 kPa at rest; Pa,O2 7.2 kPa at peak exercise). Sa,O2 was not allowed to fall below 90% during the training. The effects on exercise performance while breathing air and oxygen, and on quality of life were compared. Maximum workload (Wmax) significantly increased in the GET/RA group (mean (SD) 17 (15) W, p<0.01), but not in the GET/O2 group (7 (25) W). Six minute walking distance (6MWD), stair-climbing, weight-lifting exercise (all while breathing room air) and quality of life significantly increased in both groups. Acute administration of oxygen improved exercise performance before and after training. Training significantly increased Wmax, peak carbon dioxide production (V'CO2) and 6MWD while breathing oxygen in both groups. Differences between groups were not significant. Pulmonary rehabilitation improved exercise performance and quality of life in both groups. Supplementation of oxygen during the training did not add to the effects of training on room air.

Exercise Therapy↗

PubMed1997

Spirometry in general practice: the performance of practice assistants scored by lung function technicians.

Recently, spirometers have become available for use within general practice as an alternative to peak flow meters. This study investigates whether practice assistants, after comprehensive training, can effectively carry out spirometry with patients suffering from asthma and other chronic obstructive pulmonary diseases. A scoring system, consisting of 20 items, was devised to determine the effectiveness of the assistants' instructions and to assess the patient's subsequent use of the spirometer. About half the instructions and half the patient performance items were considered to be carried out satisfactorily.

Asthma↗

PubMed1996

Histamine induced bronchoconstriction and end tidal inspiratory activity in man.

BACKGROUND: End tidal inspiratory activity (ETIA) in diaphragm and parasternal intercostal muscles can be evoked in man and in animals by administration of histamine. Exacerbations of asthma and administration of histamine are often accompanied by hyperinflation. The aims of the study were to determine (1) the magnitude of ETIA in response to histamine in man, (2) the relative contributions of chemical and mechanical stimulation of airway receptors to ETIA, and (3) the importance of ETIA to hyperinflation. METHODS: The effects of inhalation of histamine on the electrical activities of the diaphragm and parasternal intercostal muscles measured with surface electrodes were studied in 21 subjects. The experiments were repeated after inhalation of 600 micrograms of salbutamol to prevent histamine induced bronchoconstriction and concomitant mechanical stimulation of airway receptors. Subjects were connected to a closed breathing circuit to measure the changes in functional residual capacity (FRC) for the different experiments. RESULTS: The mean values of histamine induced ETIA were 60.6% and 46.9% of peak inspiratory activities during control conditions for the diaphragm and intercostal muscles, respectively. After salbutamol histamine induced ETIA was reduced to about one quarter of pre-salbutamol values. FRC increased by 427 ml as a result of inhalation of histamine, but after salbutamol this increase was only 53 ml. The data for ETIA and FRC were interpreted as indicating that the contributions of airflow limitation and ETIA to histamine induced hyperinflation are comparable. CONCLUSIONS: Histamine is a forceful stimulus for inducing ETIA. Both chemical and mechanical stimulation of airway receptors contribute to evoke ETIA, of which the contribution of mechanical stimulation is the more important one. ETIA contributes substantially to histamine induced hyperinflation.

Adolescent↗

PubMed1996

Effects of salbutamol on rat diaphragm contractility.

The aim of this study was to investigate 1) the effects and time course of single doses of salbutamol on isometric contractile properties of isolated rat diaphragm strips and 2) whether these effects were caused by a direct effect on the muscle. Two experiments were performed. In one, salbutamol was administered subcutaneously in doses of 12.5, 25, 50, or 100 micrograms/kg (25 and 50 micrograms/kg sc resulted in serum concentrations of approximately 9 and approximately 15 micrograms/l, respectively, 0.5 h after injection) and in vitro contractile properties were determined 0.5, 1, 2, or 4 h after administration; in the other, salbutamol was added to the tissue bath in a concentration of < or = 2, approximately 10, approximately 20, and approximately 80 micrograms/l. Twice force, maximal tetanic force, and twitch force-to-tetanic force ratio all increased in a dose-dependent way in both experiments. The increases in force generation were slightly higher after subcutaneous administration. Force-frequency curves were shifted upward in both experiments. No significant effects of time of salbutamol administration were found, but the increase in force generation was most pronounced within 2 h after subcutaneous administration. In conclusion, in vitro force generation can be improved by low concentrations of salbutamol. The slightly higher increases in force generation after subcutaneous administration suggest that in vivo salbutamol may have additional positive inotropic actions on diaphragm contractility besides a direct beta 2-adrenergic effect on the muscle itself.

Albuterol↗