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Biomedical subjects

G Scano

Publications and source records attributed to G Scano.

At least 19 recordsLinked to original sources
PubMed2000

Mechanisms involved in airway obstruction: the role of smooth muscle.

Structural changes in the airway walls that are probably driven by mediators released as a consequence of chronic allergic inflammation are prominent features of asthma. However, it is not clear how each of the many changes that occur in the airway wall contribute to altered airway function in asthma. Collagen deposition in the subepithelial matrix, around and inside the smooth muscle, would be expected to oppose the effect of smooth-muscle contraction. Conversely, geometric factors would result in exaggerated airway narrowing for a given degree of smooth-muscle shortening; decreased airway wall stiffness and increased airway narrowing for a given amount of force generated by the smooth muscle. Degradation of the matrix may alter the coupling between muscle and lung recoil, allowing exaggerated smooth-muscle shortening. Increase in muscle mass associated with preservation of its contractile capacity could be the most important contributor to exaggerated airway narrowing.

Airway Obstruction↗
PubMed2000

Diagnostic accuracy of sputum outcomes in chronic stable asthma.

BACKGROUND: Asthma with non-remitting airflow obstruction may not always be differentiated from COPD with airway hyperreactivity. Many attempts have been made to find useful markers for the distinction between these two disorders. OBJECTIVE AND METHODS: In order to help the finding of a useful marker for the diagnosis of asthma in the population of patients with airway obstruction we analysed the diagnostic accuracy of sputum eosinophils and sputum ECP in 91 patients with asthma, 15 patients with chronic bronchitis, 32 patients with chronic obstructive pulmonary disease (COPD) and 20 controls subjects, by performing ROC analysis. RESULTS: Sputum eosinophils were above the normal range of our laboratory (0-3.7%) in 48 asthma patients and in six COPD patients, while sputum ECP (normal range < 85 microg/L) was high in 65 asthma patients, in 24 COPD patients and in nine chronic bronchitis patients. The ROC analysis revealed that sputum eosinophils count (AUC = 0.82) was more accurate than both sputum ECP levels (AUC = 0.56) (P < 0.0001) and beta2-reversibility (AUC = 0.53) (P = 0.0001) in differentiating asthmatic from non-asthmatic subjects (COPD, chronic bronchitis patients and normal subjects). The diagnostic accuracy of ECP was similar to that of bronchial reversibility (P = 0.76). When ROC analysis was performed by including only patients with airway obstruction (36 asthmatics with airway obstruction and COPD patients), both eosinophil count (AUC = 0.77) and beta2-reversibility (AUC = 0.66) were more accurate than ECP measurement (AUC = 0.39) in discriminating asthmatics from COPD patients (P < 0.00001 and P = 0.04, respectively). CONCLUSION: Sputum eosinophils seem to be valid markers for detecting asthma in a population of patients with airway obstruction. Moreover, the higher diagnostic accuracy of eosinophils in the sputum compared to sputum ECP and bronchial reversibility reinforces the role of cytological analysis of sputum in the diagnosis of chronic stable bronchial asthma.

Adolescent↗
PubMed2000

Airway obstruction and chronic exertional dyspnoea in patients with persistent bronchial asthma.

In patients with COPD, flow limitation (FL) predicts chronic exertional dyspnoea (CED) better than routine spirometry. Whether, and to what extent, FL and CED are overlapping quantities in chronic asthma has not yet been defined. Forty consecutive clinically stable asthmatic patients without smoking history or cardiopulmonary disorders, were studied. In each subject respiratory function, including static and dynamic pulmonary volumes, was evaluated; maximal (MEFV) and partial (PEFV) expiratory V'-V curves and isovolumic partial to maximal flow ratio (M/P). FL was assessed in a seated patient by comparing tidal and PEFV curves; FL was detected when tidal flows were superimposed or exceeded those obtained during PEFV curves, and was expressed as a percentage of the expired control tidal volume (V(T)) affected by flow limitation (FL% VT). Dyspnoea was assessed by both MRC scale and Baseline Dyspnoea Index (BDI) focal score. Half of the patients were found to have FL. They were older, more dyspnoeic and more obstructed (P<0.03 - P<0.000005) than the non-FL group. FEV1, vital capacity (VC), age, body mass index, FL and M/P ratio were all related to dyspnoea scores. FL was significantly related to FEV1 (r = - 0.59). Multiple regression analysis showed that FEV1 (P=0.003, r2= 15-3% and P = 0.004, r2= 20.3%) and age (P = 0.0006, r2 = 26.8% and P = 0.016, r2 = 11%) independently predicted a part of the variance of MRC (P = 0.0001, r2 = 42.1%) and BDI (P = 0.0008, r2 = 31.3%), respectively. With dyspnoea scale being the gold standard, diagnostic accuracy (sensitivity and specificity) by ROC (receiver operating characteristics) analysis was similar for FEV1 and FL. The results indicate that FL may be present in this subset of asthmatics. CED may not be easily explained by abnormalities of routine spirometry or FL, the largest part of the CED variance remained unexplained. Thus, routine spirometry, FL and CED in patients with bronchial asthma are only partially overlapping quantities which need to be assessed separately.

Adolescent↗
PubMed2000

Mechanism of CO(2) retention in patients with neuromuscular disease.

BACKGROUND: In many studies of patients with muscle weakness, chronic hypercapnia has appeared to be out of proportion to the severity of muscle disease, indicating that factors other than muscle weakness are involved in CO(2) retention. In patients with COPD, the unbalanced inspiratory muscle loading-to-strength ratio is thought to trigger the signal for the integrated response that leads to rapid and shallow breathing and eventually to chronic hypercapnia. This mechanism, although postulated, has not yet been assessed in patients with muscular dystrophy. SUBJECTS: Twenty consecutive patients (mean age, 47.6 years; range, 23 to 67 years) were studied: 11 patients with limb-girdle dystrophy, 3 with Duchenne muscular dystrophy, 1 with Charcot-Marie-Tooth syndrome, 1 with Becker muscular dystrophy, 1 with myotonic dystrophy, 1 with facioscapulohumeral dystrophy, and 2 with amyotrophic lateral sclerosis, without any respiratory complaints. Seventeen normal subjects matched for age and sex were studied as a control group. METHODS: Routine spirometry and arterial blood gases, maximal inspiratory and expiratory muscle pressures (MIP and MEP, respectively), and pleural pressure during maximal sniff test (Pplsn), were measured. Mechanical characteristics of the lung were assessed by evaluating lung resistance (RL) and dynamic elastance (Eldyn). Eldyn was assessed as absolute value and as percent of Pplsn; Eldyn (%Pplsn) indicates the elastic load per unit of inspiratory muscle force. Breathing pattern was assessed in terms of time (inspiratory time [TI]; respiratory frequency [Rf]) and volume (tidal volume [VT]) components of the respiratory cycle. RESULTS: A rapid shallow breathing pattern, as indicated by a greater Rf/VT ratio and a lower TI, was found in study patients compared to control subjects. Eldyn was greater in study patients, while MIP, MEP, and Pplsn were lower. PaCO(2) inversely related to VT, TI, and Pplsn (p = 0.012, p = 0.019, and p = 0.002, respectively), whereas it was directly related to Rf, Rf/VT, Eldyn, and Eldyn (%Pplsn) (p < 0.004 to p < 0.0001). Also Eldyn (%Pplsn) inversely related to TI, and the latter positively related to VT. In other words, increase in Eldyn (%Pplsn) was associated with decrease in TI, and the latter was associated with lower VT and greater PaCO(2). Mechanical and breathing pattern variables were introduced in a stepwise multiple regression that selected Eldyn (%Pplsn) (p < 0.0001; r(2) = 0.62) as a unique independent predictor of PaCO(2). CONCLUSIONS: The present study shows that in patients with neuromuscular disease, elastic load and respiratory muscle weakness are responsible for a rapid and shallow breathing pattern leading to chronic CO(2) retention.

Adult↗
PubMed2000

Hypoxic and hypercapnic breathlessness in patients with type I diabetes mellitus.

STUDY OBJECTIVES: The putative role of the performance of inspiratory muscles and breathing pattern in inducing dyspnea has been recently assessed during hypoxic stimulation in patients with type I diabetes (IDDM). Compared to a hypoxic stimulus, a hypercapnic stimulus, which may differently affect the pattern of breathing, could therefore modulate the coupling between respiratory effort and ventilatory output, which is involved in dyspnea sensation. SUBJECTS: Eight stable patients aged 19 to 48 years old, with IDDM (duration of disease, 36 to 240 months) and no smoking history, cardiopulmonary involvement, or autonomic neuropathy; and an age- and sex-matched control group. MEASUREMENTS: Pulmonary volumes, diffusing capacity of the lung for carbon monoxide, time and volume components (tidal volume [VT] and respiratory frequency), dynamic elastance (Eldyn), and swings in pleural pressure (Pessw) were measured. Maximal inspiratory pleural pressure (Pes) during a maximal sniff maneuver (Pessn), respiratory muscle effort or output (Pessw%Pessn), tension time index (TTI) = TI/total breathing cycle time x Pessw(%Pessn), and swing in Pes during VT as a percentage of Pessn were also evaluated. Dyspnea sensation was assessed by a modified Borg scale. Subjects were studied at baseline and during hypoxic and hypercapnic rebreathing tests. RESULTS: Compared to control subjects, patients exhibited normal routine spirometric function and Pessn, but a higher Eldyn, indicating peripheral airway involvement. In patients, but not in control subjects, Eldyn increased during both chemical stimuli and increased more during hypoxia than during hypercapnia. Also, changes in both VT and Pessw(%Pessn) on changes in PCO(2) were lower, while changes in Pessw(%Pessn)/VT, an index of neuroventilatory dissociation (NVD) of the ventilatory pump, on changes in PCO(2) were greater. Changes in VT and NVD for unit change in arterial oxygen saturation were lower and higher, respectively. Changes in Borg scale per changes in NVD were greater during both stimuli. Furthermore, compared to hypoxic conditions, a greater VT for any level of both minute volume and Pessw(%Pessn), and lower changes in Borg scale on changes in Pessw(%Pessn) and Pessw(%Pessn)/VT were found in hypercapnia. Changes in NVD and Borg scale related to changes in Eldyn with both chemical stimuli. CONCLUSIONS: In IDDM, the greater perception of dyspnea is associated with changes in inspiratory effort being out of proportion to changes in VT. The greater increase in Eldyn and the lower increase in VT may, in part, account for the greater perception of breathlessness during hypoxia.

Adult↗
PubMed2000

Perception of bronchoconstriction and bronchial hyper-responsiveness in asthma.

The inter-relationship between the perception of bronchoconstriction, bronchial hyper-responsiveness and temporal adaptation in asthma is still a matter of debate. In a total of 52 stable asthmatic patients, 32 without airway obstruction ¿forced expiratory volume in 1 s (FEV(1))/vital capacity (VC) 84.1% (S.D. 7.9%), and 20 with airway obstruction [FEV(1)/VC 60% (4%)], we assessed the perception of bronchoconstriction during methacholine inhalation by using: (i) the slope and intercept of the Borg and VAS (Visual Analog Scale) scores against the decrease in FEV(1), expressed as a percentage of the predicted value; and (ii) the Borg and VAS scores at a 20% decrease in FEV(1) from the lowest post-saline level (PB(20)). Bronchial hyper-responsiveness was assessed as the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)FEV(1)). The reduction in FEV(1) was significantly related to the Borg and VAS scores, with values for the group mean slope and intercept of this relationship of 0.13 (S.D. 0.08) and -1.1 (3.02) for Borg, and 1.5 (1.19) and -12.01 (35) for VAS. PB(20) was 3 (1.75) with Borg scores and 34.6 (20.5) with VAS scores. Compared with the subgroup without airway obstruction, the obstructed subgroup exhibited similar slopes, but lower Borg and VAS intercepts. For similar decreases in FEV(1) (5-20% decreases from the lowest post-saline values), the Borg and VAS scores were lower in the non-obstructed than in the obstructed subgroup. PC(20)FEV(1) was significantly related to both Borg PB(20) and VAS PB(20) when considering all patients. When assessing the subgroups, PC(20)FEV(1) was related to Borg PB(20) and VAS PB(20) in the non-obstructed subjects, but not in the obstructed subjects. In neither subgroup was the log of the cumulative dose related to the Borg and VAS scores at the end of the test. We conclude that, unlike in previous studies, the ability to perceive acute bronchoconstriction may be reduced as background airflow obstruction increases in asthma. Bronchial hyper-responsiveness did not play a major role in perceived breathlessness in patients without airway obstruction, and even less of a role in patients with obstruction. The cumulative dose of agonist did not appear to influence the perception of bronchoconstriction.

Adolescent↗
PubMed1999

Sputum analysis, bronchial hyperresponsiveness, and airway function in asthma: results of a factor analysis.

BACKGROUND: Recent studies have shown weak associations among FEV1, bronchial hyperresponsiveness (BHR), sputum eosinophils, and sputum eosinophil cationic protein (ECP), suggesting that they are nonoverlapping quantities. The statistical method of factor analysis enables reduction of many parameters that characterize the disease to a few independent factors, with each factor grouping associated parameters. OBJECTIVE: The purpose of this study was to demonstrate, by using factor analysis, that reversible airway obstruction, BHR, and eosinophilic inflammation of the bronchial tree, as assessed by cytologic and biochemical analysis of sputum, may be considered separate dimensions that characterize chronic bronchial asthma. METHODS: Ninety-nine clinically stable patients with a previous diagnosis of asthma underwent spirometry, sputum induction, and histamine inhalation tests. RESULTS: Most patients were nonobstructed (FEV1, 91% +/- 20%); a low level of bronchial reversibility (FEV1 increase after beta2 -agonist, 7.8% +/- 9.2%) and BHR (histamine PC20 FEV1 geometric mean, 0.98 mg/mL) were found. Sputum eosinophil differential count (12.4% +/- 17.7%) and sputum ECP (1305 +/- 3072 microg/mL) were in the normal range of our laboratory in 38 and 22 patients, respectively. Factor analysis selected 3 different factors, explaining 74.8% of variability. Measurements of airway function and age loaded on factor I, PC20 FEV1 and beta2 -response loaded on factor II, and sputum ECP and eosinophils loaded on factor III. Additional post hoc factor analyses provided similar results when the sample was divided into 2 subgroups by randomization, presence of airway obstruction, degree of BHR, percentage of sputum eosinophils, or concentration of sputum ECP. CONCLUSIONS: We conclude that airway function, baseline BHR, and airway inflammation may be considered separate dimensions in the description of chronic asthma. Such evidence supports the utility of routine measurement of all these dimensions.

Adolescent↗
PubMed1999

Chest wall kinematics and respiratory muscle action in walking healthy humans.

We studied chest wall kinematics and respiratory muscle action in five untrained healthy men walking on a motor-driven treadmill at 2 and 4 miles/h with constant grade (0%). The chest wall volume (Vcw), assessed by using the ELITE system, was modeled as the sum of the volumes of the lung-apposed rib cage (Vrc,p), diaphragm-apposed rib cage (Vrc,a), and abdomen (Vab). Esophageal and gastric pressures were measured simultaneously. Velocity of shortening (V(di)) and power [Wdi = diaphragm pressure (Pdi) x V(di)] of the diaphragm were also calculated. During walking, the progressive increase in end-inspiratory Vcw (P < 0.05) resulted from an increase in end-inspiratory Vrc,p and Vrc,a (P < 0.01). The progressive decrease (P < 0.05) in end-expiratory Vcw was entirely due to the decrease in end-expiratory Vab (P < 0.01). The increase in Vrc,a was proportionally slightly greater than the increase in Vrc,p, consistent with minimal rib cage distortion (2.5 +/- 0.2% at 4 miles/h). The Vcw end-inspiratory increase and end-expiratory decrease were accounted for by inspiratory rib cage (RCM,i) and abdominal (ABM) muscle action, respectively. The pressure developed by RCM,i and ABM and Pdi progressively increased (P < 0.05) from rest to the highest workload. The increase in V(di), more than the increase in the change in Pdi, accounted for the increase in Wdi. In conclusion, we found that, in walking healthy humans, the increase in ventilatory demand was met by the recruitment of the inspiratory and expiratory reserve volume. ABM action accounted for the expiratory reserve volume recruitment. We have also shown that the diaphragm acts mainly as a flow generator. The rib cage distortion, although measurable, is minimized by the coordinated action of respiratory muscles.

Abdominal Muscles↗
PubMed1999

Chest wall hyperinflation during acute bronchoconstriction in asthma.

The mechanics of the chest wall was studied in seven asthmatic patients before and during histamine-induced bronchoconstriction (B). The volume of the chest wall (VCW) was calculated by three-dimensional tracking of 89 chest wall markers. Pleural (Ppl) and gastric (Pga) pressures were simultaneously recorded. VCW was modeled as the sum of the volumes of the pulmonary-apposed rib cage (VRC,p), diaphragm-apposed rib cage (VRC,a), and abdomen (VAB). During B, hyperinflation was due to the increase in end-expiratory volume of the rib cage (0.63 +/- 0.09 L, p < 0.01), whereas change in VAB was inconsistent (0.09 +/- 0.07 L, NS) because of phasic recruitment of abdominal muscles during expiration. Changes in end-expiratory VRC,p and VRC,a were along the rib cage relaxation configuration, indicating that both compartments shared proportionally the hyperinflation. VRC,p-Ppl plot during B was displaced leftward of the relaxation curve, suggesting persistent activity of rib cage inspiratory muscles throughout expiration. Changes in end-expiratory VCW during B did not relate to changes in FEV(1) or time and volume components of the breathing cycle. We concluded that during B in asthmatic patients: (1) rib cage accounts largely for the volume of hyperinflation, whereas abdominal muscle recruitment during expiration limits the increase in VAB; (2) hyperinflation is influenced by sustained postinspiratory activity of the inspiratory muscles; (3) this pattern of respiratory muscle recruitment seems to minimize volume distortion of the rib cage at end-expiration and to preserve diaphragm length despite hyperinflation.

Abdominal Muscles↗
PubMed1999

Reduction in bronchodilation following a deep inhalation is poorly related to airway inflammation in asthma.

In patients with bronchial asthma, forced expiratory flows are differently sensitive to a previous volume history. A reduced ability of a deep inhalation (DI) to dilate obstructed airways has been hypothesized to be a physiological marker for the degree of airway responsiveness and to relate to the presence and magnitude of inflammation in the lung, even in mild stable asthma. However, there are at present doubts as to whether functional changes could be used as a substitute for airway inflammation studies. In order to investigate the interrelations among airway inflammation, bronchial hyperresponsiveness and effects of volume history, 58 consecutive asthmatics with mild to moderate asthma were studied. The effects of DI were assessed as the isovolumic ratio of flows from forced expiratory manoeuvres started from maximal (M) or partial (P) lung inflation. Airway inflammation was assessed by using induced sputum. Sputum was analysed for total and differential cell counts, and levels of eosinophil cationic protein (ECP) which reflects eosinophil activation. Airway responsiveness was assessed as the provocative concentration of histamine which caused a 20% fall in forced expiratory volume in one second (FEV1) from control (PC20). The M/P ratio was significantly related to ECP (r=-0.31, p<0.03) and eosinophils (r=-0.29, p<0.03), FEV1/vital capacity (VC) (r=0.32; p<0.01), clinical score (r=-0.33; p<0.03) and age (r=-0.41; p<0.0001). In a stepwise multiple regression analysis including age, score, baseline lung function, ECP, number of eosinophils and the response to beta2-agonist, age (p<0.037) predicted a small amount of the variance in M/P ratio (r2=0.12). It is concluded that volume history response is substantially independent of both sputum outcomes (inflammatory cell number and eosinophil cationic protein) and bronchial hyperresponsiveness; rather it seems to be associated with anthropometric characteristics. Functional aspects do not provide information on eosinophilic, probably central, airway inflammation.

Adult↗
PubMed1999

Respiratory muscle function and hypoxic ventilatory control in patients with type I diabetes.

STUDY OBJECTIVES: The interaction among pulmonary mechanics, respiratory muscle performance, and ventilatory control in subjects with insulin-dependent diabetes mellitus has so far received little attention. We therefore decided to assess the role of central factors and peripheral factors on the ventilatory response to a hypoxic stimulus in type I diabetic patients. SUBJECTS: Eight patients in stable condition aged 19 to 48 years old, with insulin-dependent diabetes mellitus (duration of the disease, 36 to 240 months) and no history of smoking, cardiopulmonary involvement, or autonomic neuropathy; and an age- and gender-matched control group. MEASUREMENTS: In each patient, we measured the following: pulmonary volumes; diffusing capacity of the lung for carbon monoxide (D(LCO)); time and volume components of ventilation (tidal volume [V(T)] and respiratory frequency); static compliance (Clstat) and dynamic compliance (Cldyn); swings in pleural pressure (Pes) and gastric pressure (Pg); and transdiaphragmatic pressure (Pdi), obtained by subtracting Pes from Pg. Maximal inspiratory Pes and Pdi during a maximal sniff maneuver were also measured. Swings in Pes and Pdi during V(T) as a percentage of Pes and Pdi during the maximal sniff maneuver [Pessw(%Pessn) and Pdisw(%Pdisn), respectively] were both considered as a measure of central respiratory output, and the Pessw(%Pessn)/V(T) ratio was considered as an index of neuroventilatory dissociation (NVD) of the inspiratory pump. Subjects were studied at baseline and during hypoxic rebreathing. RESULTS: Pulmonary volumes and D(LCO) were normal or slightly reduced. A lower Cldyn, higher central respiratory output, and NVD were found. During hypoxic rebreathing, patients had lower V(T), similar central respiratory output, and greater NVD per unit change in arterial oxygen saturation compared with values in control subjects. An increase in dynamic elastance, computed as 1/Cldyn, during hypoxia was found in patients, but not in normal subjects, and was directly related to concurrent changes in NVD. CONCLUSIONS: We have shown that the assessment of a normal Clstat and normal routine parameters of airway obstruction does not permit the definite exclusion of the role of peripheral airway involvement in insulin-dependent diabetes mellitus. Peripheral airway involvement is likely to influence indices of hypoxic ventilator) drive by modulating a normal central motor output into a rapid and shallow pattern of ventilatory response.

Adult↗
PubMed1999

Dyspnoea, peripheral airway involvement and respiratory muscle effort in patients with type I diabetes mellitus under good metabolic control.

Dyspnoea and pulmonary dysfunction have recently been associated with Type I (insulin-dependent) diabetes mellitus. The putative role of altered pulmonary mechanics and of performance of inspiratory muscles in inducing dyspnoea has not been yet assessed in Type I diabetes. To better focus on this topic we evaluated nine patients with Type I diabetes mellitus, aged 19 to 48 years with good and stable metabolic control, without a history of smoking and microvascular complications, alongside a group of 14 healthy control subjects. In each subject, pulmonary volumes, static and dynamic compliance, pleural pressure swings (Pplsw), maximal inspiratory pressures (Pplsn), Pplsw(%Pplsn), a measure of respiratory muscle effort, and tension-time index [TTI=TI/TTOTxPplsw(%Pplsn)] were measured (TI=inspiratory time;TTOT=total time of the respiratory cycle). All subjects were studied at baseline and during hypoxic rebreathing. Patients had normal pulmonary volumes. During hypoxic rebreathing, a normal change in respiratory muscle effort [DeltaPplsw(%Pplsn)/DeltaSaO2] and DeltaTTI/DeltaSaO2, and a lower change in tidal volume versus change in oxygen saturation [DeltaVT(% vital capacity)/DeltaSaO2], resulted in a higher ratio of respiratory effort to tidal volume [Pplsw(%Pplsn)/VT(% vital capacity)], a measure of neuroventilatory dissociation of the respiratory pump. Hypoxic dyspnoea, assessed by a modified Borg scale, showed a greater rate of rise (DeltaBorg/DeltaSaO2) and a greater increase for a given level of respiratory effort in patients. Moreover, neuroventilatory dissociation related to the expression of peripheral airway involvement, as assessed in terms of low dynamic compliance, and to concurrent change in dyspnoea sensation. Patients with Type I diabetes mellitus under good metabolic control and with normal lung volumes may have abnormal peripheral airway function. The latter is thought to be responsible for the association between dyspnoea sensation and neuroventilatory dissociation.

Adult↗
PubMed1999

Normal thoracoabdominal motion.

An optical reflectance motion analysis (ELITE) system for the kinematic analysis of chest wall motion has recently been developed. The ELITE system is based on a television image processor permitting the three-dimensional assessment of the chest wall by automatically computing the co-ordinates of passive markers placed on the thorax and abdomen. Tracking 86 chest wall markers allows the volume of the lung- and diaphragm-apposed ribcage compartments and the abdomen to be calculated. This system has been proven reliable and accurate in a number of experimental conditions. Dynamic measurements obtained by combining respiratory pressure measurements with chest wall compartment volumes, determined by means of the ELITE system, has recently permitted the assessment of changes in respiratory muscle action relative to changes in chest wall compartment volumes in humans during walking or cycling exercise.

Abdominal Muscles↗
PubMed1999

The ELITE system.

This report describes the technical limitations that affect the computation of thoraco-abdominal volume displacement and the characteristics that an ideal system should have. The elaboratore di immagini televisive (ELITE) system satisfies many of these characteristics. ELITE system is an optoelectronic device able to track the three-dimensional co-ordinates of a number of reflecting markers placed noninvasively on the skin of the subject. The simultaneous acquisition of kinematic signals with pleural and gastric pressures during a relaxation manoeuvre allows the representation of pressure-volume plots describing the mechanical characteristics of each compartment. The results of studies concerning chest-wall mechanics by applying the ELITE system are described.

Abdomen↗
PubMed1999

Respiratory muscles in internal medicine.

This review provides evidence that respiratory muscle abnormalities are present in many illnesses of internal medicine and emphasizes that clinicians should look for respiratory muscle weakness in many circumstances, particularly immunological disorders. Controversial results in hormonal diseases, metabolic diseases and abdominal disorders indicate areas for further research.

Humans↗
PubMed1999

Physiological changes during severe airflow obstruction in chronic obstructive pulmonary disease.

Chronic expiratory flow limitation and hyperinflation are the mechanical hallmarks of chronic obstructive pulmonary disease (COPD). Although carbon dioxide retention is dependent on the severity of airflow limitation, there is considerable variability in the relationships between arterial carbon dioxide tension (Pa,CO2) and forced expiratory volume in one second (FEV1) or total lung resistance (RL). In stable COPD patients with severe airflow obstruction, shallow breathing and inspiratory muscle weakness are the main factors associated with CO2 retention. In stable COPD patients, the diaphragm is less effective than in normal subjects and, with increasing airflow obstruction and hyperinflation, the contribution to the generation of ventilatory pressure of the ribcage inspiratory muscles increased. Abdominal muscles are recruited during expiration in severe COPD patients and the expiratory rise in gastric pressure is directly related to intrinsic positive end-expiratory (alveolar) pressure (PEEPi). During acute bronchoconstriction, COPD patients with severe airflow obstruction recruited the rib cage inspiratory muscles proportionally more than the diaphragm. The associated recruitment of abdominal muscles results in a reduction in abdominal volume at end-expiration and contributes to a significant extent to PEEPi. Dynamic hyperinflation can be overestimated during chronic and acute airway obstruction if abdominal muscle function is not evaluated.

Acute Disease↗
PubMed1998

HLA class II allele and haplotype frequencies in Ethiopian Amhara and Oromo populations.

HLA class II alleles were identified in 181 healthy unrelated Ethiopian children of both sexes and in 350 European controls from the South of France. The Ethiopian individuals belonged to the two major ethnic groups of the country: Oromo (N=83) and Amhara (N=98). In both panels, genetic polymorphism of HLA class II alleles was analysed for the first time by molecular typing of DRB1, DQA1 and DQB1 loci. Allelic and phenotypic frequencies were compared with those of European controls and other African populations. Construction of HLA class II three-locus haplotypes was also performed. The study revealed some differences between the two groups. Characteristic features of Central and North African populations appeared on the Ethiopian HLA genotypes. Surprisingly, DRB1*11 presented one of the lowest gene frequencies in both Ethiopian ethnic groups in contrast to Europeans and West Africans. Furthermore, this decrease was more marked than those observed using serological techniques in other geographically close East African countries. Oromo and Amhara only showed minor differences in spite of their different origins and histories. One significant difference consisted of a lower DRB1*01 gene frequency in Oromo as reported in most West African people. Some new or rare haplotypes were also observed in the Oromo group. Our results underline the distinctive features of the Ethiopian populations among the few HLA genotyping data available for East African groups and emphasise the major interest of such investigations in this region of Africa.

Alleles↗