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Biomedical subjects

C Lisboa

Publications and source records attributed to C Lisboa.

At least 19 recordsLinked to original sources
PubMed2005

[Limitations of the technique to determine hydrogen peroxide levels in exhaled breath condensate from patients with adult respiratory distress syndrome].

OBJECTIVE: Exhaled breath condensate represents an alternative to bronchoalveolar lavage for the analysis of markers of inflammation and oxidative stress in patients with adult respiratory distress syndrome (ARDS). However, analysis of hydrogen peroxide (H2O2) yields variable results that do not correlate with severity of the clinical presentation. In an attempt to explain this variability, the aim of the present study was to assess the possible limitations of the most commonly used technique for analyzing H2O2 in breath condensate. PATIENTS AND METHODS: H2O2 levels were analyzed using the Gallati technique (linear range between 0.3 and 10 microM, r=0.99; P<.05) in serial samples of condensate taken from the expiratory tube of a mechanical ventilator in 6 patients with ARDS. RESULTS: The volume of condensate obtained correlated to minute ventilation (r=0.96; P<.05). In 11 out of 23 samples, a spectrophotometer reading was obtained at 450 nm despite the absence of the characteristic color of the reaction and in some of these samples a spontaneous reading was obtained that was indicative of contamination. The absorbance spectrum of these samples did not contain the characteristic peak for H2O2 at 450 nm and pretreatment of some samples with catalase did not affect the absorbance at 450 nm. CONCLUSIONS: The spectrophotometric method commonly used to measure H2O2 levels in breath condensate lacks specificity in ARDS due to the presence of variable levels of contaminants in the samples, which lead to false positives.

Breath Tests↗
PubMed2005

Physiological and clinical effects of diurnal noninvasive ventilation in hypercapnic COPD.

To assess the clinical impact of noninvasive mechanical ventilation (NIMV) on stable hypercapnic chronic obstructive pulmonary disease, changes in exercise capacity, dyspnoea and simple physiological parameters were evaluated. The time course of these effects during treatment and recovery was also assessed. Patients were randomly allocated to NIMV (n=27) or sham-NIMV (n=15), applied 3 h.day-1, 5 days a week, for 3 weeks. A 6-min walking distance (6MWD), arterial blood gases, spirometry, pattern of breathing, mouth occlusion pressure (P0.1), and respiratory system impedance (P0.1/tidal volume (VT)/inspiratory time (tI)) were measured weekly during treatment and 2 weekly during follow-up. Transition dyspnoea index (TDI) was also measured. During NIMV, carbon dioxide arterial tension decreased progressively, concomitantly with a slow deep pattern of breathing, a proportional increase in the forced expiratory volume in one second (FEV1), the forced vital capacity and significant reductions of P0.1 and P0.1/VT/tI. The 6MWD improved by a mean of 76 m after NIMV, and by 73 m and 61 m 1 and 2 weeks, respectively, after treatment. Dyspnoea improved with a mean TDI of three points. Changes in 6MWD were highly related to TDI and to a lesser extent to changes in FEV1 (r=0.60). The current authors conclude that noninvasive mechanical ventilation has significant and sustained clinical impact in stable hypercapnic chronic obstructive pulmonary disease.

Aged↗
PubMed2003

Dermatological and ophthalmological sequels in toxic epidermal necrolysis.

BACKGROUND: Toxic epidermal necrolysis (TEN) is a rare, drug-induced disease characterized by epidermal detachment and mucosal involvement. After an acute period, potentially disabling cutaneous and ocular sequels may appear. Although long-term complications are not rare, only few outcome studies are published. OBJECTIVE: To evaluate the incidence of dermatological and ophthalmological sequels following TEN, to describe its clinical aspects and correlation with acute involvement. PATIENTS AND METHODS: Eight patients surviving to TEN were submitted to dermatological and ophthalmological observation ranging from 0.5 to 8 years after hospitalization. Cutaneous and ocular involvement, during the acute phase, was retrospectively analysed. RESULTS: Dermatological sequels were observed in 6 patients (75%) corresponding to those with more extensive skin involvement in the acute phase. The most frequent complications were cutaneous dyschromia (62.5%) and nail dystrophies (37.5%). Six patients (75%) had ocular complications with tarsal conjunctiva keratinization in 5 (62.5%) and keratoconjunctivitis sicca in 4 of them (50%). Trichiasis, corneal neovascularization and symblepharon were observed in 1 case. There was no correlation between the severity of acute ocular involvement and long-term complications. CONCLUSION: Following TEN, most patients have dermatological and ophthalmological sequels that persist for several years.

Adolescent↗
PubMed2002

Cd8(+)/V beta 5.1(+) large granular lymphocyte leukemia associated with autoimmune cytopenias, rheumatoid arthritis and vascular mammary skin lesions: successful response to 2-deoxycoformycin.

We report a case of CD8(+)/V beta 5.1(+) T-cell large granular lymphocyte leukemia (T-LGL leukemia) presenting with mild lymphocytosis, severe autoimmune neutropenia, thrombocytopenia, polyarthritis and recurrent infections with a chronic disease course. Immunophenotyping showed an expansion of CD3(+)/TCR alpha beta(+)/CD8(+bright)/CD11c(+)/CD57(-)/CD56(-) large granular lymphocytes with expression of the TCR-V beta 5.1 family. Southern blot analysis revealed a clonal rearrangement of the TCR beta-chain gene. Hematopoietic growth factors, high dose intravenous immunoglobulin and corticosteroids were of limited therapeutic benefit to correct the cytopenias. During the disease course, the patient developed a severe cutaneous leg ulcer and bilateral vascular mammary skin lesions. Treatment with 2-deoxycoformycin resulted in both clinical and hematological complete responses, including the resolution of vascular skin lesions. Combined immuno-staining with relevant T-cell associated and anti-TCR-V beta monoclonal antibodies proved to be a sensitive method to assess the therapeutic effect of 2-deoxycoformicin and to evaluate the residual disease.

Aged↗
PubMed2002

Effects of noninvasive ventilation on lung hyperinflation in stable hypercapnic COPD.

Two previous uncontrolled studies have suggested that noninvasive mechanical ventilation (NIMV) in patients with hypercapnic chronic obstructive pulmonary disease (COPD) improves arterial blood gas tensions by decreasing lung hyperinflation with the consequent reduction in inspiratory loads and changes in ventilatory pattern. The aim of this randomised placebo-controlled study was to determine whether these mechanisms play a pivotal role in the effects of NIMV on arterial blood gases. Thirty-six stable hypercapnic COPD patients were randomly allocated to NIMV or sham NIMV. A 2-week run-in period was followed by a 3-week study period, during which ventilation was applied 3 h x day(-1), 5 days a week. Arterial blood gases, spirometry, lung volumes, and respiratory mechanics were measured before and after application of NIMV. Patients submitted to NIMV showed changes (mean (95% confidence interval)) in daytime arterial carbon dioxide tension (Pa,CO2) and arterial oxygen tension of -1.12 (-1.52-0.73) kPa (-8.4 (-11.4-5.5) mmHg) and 1.14 (0.70-1.50) kPa (8.6 (5.3-11.9) mmHg), respectively. Total lung capacity, functional residual capacity (FRC) and residual volume were found to be reduced by 10 (7-13), 25 (18-31), and 36 (27-45)% of their predicted value, respectively, whereas forced expiratory volume in one second and forced vital capacity increased by 4 (1.5-6.9) and 9 (5-13)% pred, respectively. Tidal volume (VT) increased by 181 (110-252) mL. All of the above changes were significant compared with sham NIMV. Changes in Pa,CO2 were significantly related to changes in dynamic intrinsic positive end-expiratory pressure, inspiratory lung impedance, VT and FRC. It was concluded that the beneficial effects of noninvasive mechanical ventilation could be explained by a reduction in lung hyperinflation and inspiratory loads.

Aged↗
PubMed2001

Bleomycin-induced chronic lung damage does not resemble human idiopathic pulmonary fibrosis.

Administration of bleomycin into the lungs of experimental animals has been utilized as a model to understand human pulmonary fibrosis. Most of the studies, however, have focused on early stages of the lung reaction. We hypothesized that chronic stages of the model may not mimic idiopathic pulmonary fibrosis, since in preliminary studies, lung volume and compliance were not decreased. Eight male Sprague-Dawley rats receiving intratracheal bleomycin (0.5 U/100 g body weight) underwent measurement of FRC, inspiratory capacity, and lung compliance 120 d later. Lung histologic changes were evaluated using light microscopy. Eight rats without intervention served as controls. Results show that our model, in early stages, has histologic changes no different from those previously described elsewhere. In chronic stages, however, the model does not behave as a restrictive syndrome: FRC is normal or increased, whereas lung compliance is normal. Focal peribronchiolar inflammation and fibrosis associated with paracicatricial emphysematous changes are the main histologic features of long-term lung remodeling after bleomycin. We conclude that while the chronic stages of the model may be informative in understanding mechanisms of fibrosis, care should be taken not to extrapolate to human idiopathic pulmonary fibrosis. We speculate that the model might resemble a particular subgroup of human interstitial lung disease, namely, those involving peribronchiolar structures.

Animals↗
PubMed2001

Breathing pattern and gas exchange at peak exercise in COPD patients with and without tidal flow limitation at rest.

Expiratory flow limitation (FL) at rest is frequently present in chronic obstructive pulmonary disease (COPD) patients. It promotes dynamic hyperinflation with a consequent decrease in inspiratory capacity (IC). Since in COPD resting IC is strongly correlated with exercise tolerance, this study hypothesized that this is due to limitation of the maximal tidal volume (VT,max) during exercise by the reduced IC. The present study investigated the role of tidal FL at rest on: 1) the relationship of resting IC to VT,max; and 2) on gas exchange during peak exercise in COPD patients. Fifty-two stable COPD patients were studied at rest, using the negative expiratory pressure technique to assess the presence of FL, and during incremental symptom-limited cycling exercise to evaluate exercise performance. At rest, FL was present in 29 patients. In the 52 patients, a close relationship of VT,max to IC was found using non-normalized values (r=0.77; p < 0.0001), and stepwise regression analysis selected IC as the only significant predictor of VT,max. Subgroup analysis showed that this was also the case for patients both with and without FL (r=0.70 and 0.76, respectively). In addition, in FL patients there was an increase (p < 0.002) in arterial carbon dioxide partial pressure at peak exercise, mainly due to a relatively low VT,max and consequent increase in the physiological dead space (VD)/VT ratio. The arterial oxygen partial pressure also decreased at peak exercise in the FL patients (p < 0.05). In conclusion, in chronic obstructive pulmonary disease patients the maximal tidal volume, and hence maximal oxygen consumption, are closely related to the reduced inspiratory capacity. The flow limited patients also exhibit a significant increase in arterial carbon dioxide partial pressure and a decrease in arterial oxygen partial pressure during peak exercise.

Aged↗
PubMed2001

[Strength of inspiratory muscles in chronic heart failure and chronic pulmonary obstructive disease].

BACKGROUND: The maximal pressure generated by inspiratory muscles (PIMax) is an index of their strength which is diminished in both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). Although inspiratory muscle power output (IMPO), which includes both strength and velocity of shortening, has been shown to be reduced in COPD, there is no information regarding IMPO in CHF. AIM: To measure IMPO in patients with CHF and COPD. PATIENTS AND METHODS: We studied 9 CHF patients with functional capacity II and III and 9 patients with severe COPD. Eight normal subjects of similar ages were included as controls. Power output was measured using the incremental threshold loading test. RESULTS: Maximal IMPO was significantly reduced in both groups of patients. Power output developed with each increasing load was also diminished, basically as a consequence of a reduction in Vinsp. The degree of dyspnea at the end of the test was greater in COPD than in CHF patients and normal subjects. For a given level of power, dyspnea was also greater in patients than in normals subjects. There was no decrease in SpO2 during the test. CONCLUSIONS: IMPO is equally reduced in COPD and CHF patients. Power output is better related to dyspnea than PIMax, probably because of the inclusion of shortening velocity.

Analysis of Variance↗
PubMed2001

[Selective training of respiratory muscles in patients with chronic heart failure].

BACKGROUND: Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance. AIM: To assess the effects of selective training of respiratory muscles in patients with heart failure. PATIENTS AND METHODS: Twenty patients with stable chronic heart failure, aged 58.3 +/- 3 years with an ejection fraction of 28 +/- 9%, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30% of maximal inspiratory pressure (PImax) in 11 and in 10% of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training. RESULTS: Both training loads were associated to an improvement in dyspnea (+2.7 +/- 1.8 and +2.8 +/- 1.8 score points with 30% PImax and 10% PImax respectively), maximal oxygen uptake (from 19 +/- 3 to 21.6 +/- 5 and from 16 +/- 5 to 18.6 +/- 7 ml/kg/min with 30% PImax and 10% PImax respectively, p < 0.05), PImax (from 78 +/- 22 to 99 +/- 22 and from 72 +/- 34 to 82.3 cm H20 with 30% PImax and 10% PImax respectively), sustained PImax (from 63 +/- 18 to 90 +/- 22 and from 58 +/- 3 to 69 +/- 3 cm H20 with 30% PImax and 10% PImax respectively), and maximal sustained load (from 120 +/- 67 to 195 +/- 47 and from 139 +/- 120 to 192 +/- 154 g with 30% PImax and 10% PImax respectively). The distance walked in 6 min only increased in subjects trained at 30% PImax (from 451 +/- 78 to 486 +/- 68 m). CONCLUSIONS: Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure.

Breathing Exercises↗
PubMed2001

[Quality of life in patients with chronic obstructive pulmonary disease and the impact of physical training].

BACKGROUND: Health related quality of life (QoL) is severely impaired in COPD patients as a consequence of dyspnea and limited exercise tolerance, which lead to physical deconditioning and muscle atrophy resulting in weakness and fatigue. Psychosocial factors such as depression and anxiety also contribute to this impairment. AIM: To evaluate: a) the impact of COPD on quality of life, and b) the effect of 10 weeks of exercise training on exercise performance and on QoL. PATIENTS AND METHODS: The Spanish version of the Chronic Respiratory Questionnaire (CRQ) was applied to 55 COPD patients (FEV1 37 +/- 13% pred) for the assessment of QoL and in 30 of them submitted to exercise training for 10 weeks. Exercise performance was evaluated by measuring: six-minute walking distance, maximal workload (Wmax), maximal O2 consumption (VO2max) as well as endurance time, blood lactic acid, dyspnea and leg fatigue during a submaximal exercise. Trained patients were evaluated before and after training. RESULTS: COPD patients showed a reduction (mean +/- SD) in the four domains of the CRQ: dyspnea (3.1 +/- 0.9); fatigue (4.3 +/- 1.3); mastery (4.65 +/- 1.3), emotional function (4.1 +/- 0.97), and in Wmax and VO2max (52 +/- 16 Watt and 970 +/- 301 ml/min). No significant relationship between the impairment in exercise tolerance and in QoL was observed. Exercise training significantly improved the four domains of QoL (p < 0.0001), Wmax (p < 0.05), VO2max (p < 0.02) and endurance time (p < 0.001). Isotime exercise measurements of dyspnea, leg fatigue and lactic acid decreased after training (p < 0.001, each). No significant relation between changes in QoL and changes in exercise performance were observed. CONCLUSIONS: Our results demonstrate that QoL is seriously impaired in patients with COPD and confirm: (a) the lack of relationship of QoL to the usually measured physiological parameters, and (b) the beneficial effect of exercise training on QoL through the reduction of symptoms. These findings stresses the need of measuring quality of life in our patients if we want to evaluate the impact of therapeutic procedures on well-being from the patients' perspective.

Aged↗
PubMed2001

[The six minute walking test elicits lung hyperinflation in patients with severe chronic obstructive lung disease].

BACKGROUND: Exercise tolerance in patients with COPD is highly variable and poorly related to airways obstruction assessed by FEV1. These patients develop dynamic hyperinflation (DH) during an incremental exercise test which can be evaluated through a reduction in inspiratory capacity (IC). AIM: To evaluate: a) if the six minute walking test (6 MWD) induce DH reducing IC, b) if the reduction in IC is related to tidal expiratory flow limitation at rest (FL). SUBJECTS AND METHODS: Thirty eight stable COPD patients (28 FL and ten non FL during resting breathing, determined by the negative pressure technique). Inspiratory capacity was measured before and immediately after the 6 MWD test. Dyspnea, SpO2 and heart rate were measured before and after the test. RESULTS: Inspiratory capacity was lower in FL patients as compared to patients without FL (p < 0.005). Although no differences were found between groups in 6 MWD, dyspnea and HR, a significant reduction in IC after the walking test was observed only in FL patients (p < 0.0001). In addition, SpO2 fell significantly (p < 0.0001) after walking in the same group. CONCLUSIONS: Our results demonstrate that a moderate exercise such as the walking test induces DH and hypoxemia in patients with COPD and FL and stresses the importance of assessing DH by measuring IC in these patients.

Aged↗
PubMed2001

[Computer analysis of respiratory sounds in bronchial obstruction evaluation in small children that do not collaborate with spirometry tests].

BACKGROUND: There are changes in inspiratory breath sound intensity in patients with airway obstruction. Airway narrowing may change sound spectral characteristics. AIM: To define the characteristics of lung sounds at standardized air flow during methacholine challenge and to compare acoustic changes with transcutaneous oxygen tension (PtcO2) during induced airway narrowing. PATIENTS AND METHODS: Forty asthmatic children (20 male) aged 5.2 +/- 1 years and 40 normal children (18 male), aged 5.6 +/- 1 years were studied. All patients were free of respiratory tract infections one month before the study. A methacholine challenge from 0.06 to 8 mg/ml was performed; the test was ended when a fall in PtcO2 of > 20% from baseline was observed or if the final concentration was reached. Subjects breathed through a pneumotachograph aiming at flows of 0.4 to 0.6 l/s. Respiratory sounds were recorded using contact sensors at the suprasternal notch and at the posterior right lower lobe. From average spectra, power at low (100-200 Hz = P1) and high frequencies (400-2000 = P2) was calculated. Frequencies below which 50% (F50) and 99% (SEF90) of the spectral power between 100 and 2000 Hz was contained, were also calculated. RESULTS: In asthmatics, the metacholine concentration at which a 20% fall in PtcO2 was observed, was lower than in normal children (p < 0.05). There was an increase in P1 (p < 0.01) and a reduction in P2 (p < 0.01) during inspiration, in subjects that experienced a 20% reduction in PtcO2. Also, there was an increase in F50 and SEF99 during inspiration in lung sounds, but not over the trachea. CONCLUSIONS: Lung sounds analysis can be useful for the assessment of airway reactivity in asthmatic children.

Asthma↗
PubMed2000

Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest.

Expiratory flow limitation promotes dynamic hyperinflation during exercise in chronic obstructive pulmonary disease (COPD) patients with a consequent reduction in inspiratory capacity (IC), limiting their exercise tolerance. Therefore, the exercise capacity of patients with tidal expiratory flow limitation (FL) at rest should depend on the magnitude of IC. The presented study was designed to evaluate the role of FL on the relationship between resting IC, other respiratory function variables and exercise performance in COPD patients. Fifty-two patients were included in the study. Negative expiratory pressure (NEP) uptake (VO2,max) were measured during an incremental symptom-limited cycle exercise. Twenty-nine patients were FL at rest. The IC was normal in all non-FL patients, while in most FL subjects it was decreased. Both WRmax and VO2,max were lower in FL patients (p<0.001, each). A close relationship of WRmax and O2,max to IC was found (r=0.73 and 0.75, respectively; p<0.0001, each). In the whole group, stepwise regression analysis selected IC and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (% predicted) as the only significant contributors to exercise tolerance. Subgroup analysis showed that IC was the sole predictor in FL patients, and FEV1/FVC in non-FL patients. Detection of flow limitation provides useful information on the factors that influence exercise capacity in chronic obstructive pulmonary disease patients. Accordingly, in patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.

Aged↗