RESUMEN
BACKGROUND: Increased pulmonary epithelial permeability evaluated by the rate of clearance from lung to blood of the radioaerosol solute technetium-99m labelled diethylenetriamine pentaacetate (99mTc-DTPA) has been reported in smokers and in workers exposed to silica dust. A study was carried out to determine whether there are additive effects of cigarette smoke and exposure to silica dust on clearance rates of 99mTc-DTPA in ceramic workers. METHODS: Thirty one subjects with silicosis were studied, of whom 18 smoked cigarettes and 13 were non-smokers. They had similar histories of exposure to silica dust, and radiological alterations consistent with silicosis. The results from these patients were compared with those from normal subjects and smokers previously studied by the authors. RESULTS: Pulmonary function values were normal in most patients and not significantly different among groups. The median (range) rate of clearance of 99mTc-DTPA in smokers with silicosis was 4.1 (1.9-12.7) %/minute, which was higher than the rates in non-smoking patients with silicosis of 2.2 (1.1-6.6) %/minute and in smokers without exposure to silica dust of 2.9 (1.6-4.5) %/minute. These differences were more evident and significant when the clearance rates of the lower lobes of the three groups were compared. Clearance rates higher than 3%/minute were much more frequent in smokers with silicosis (85%) than in non-smoking patients with silicosis (15%) and in smokers (40%). CONCLUSION: In ceramic workers with radiographic changes resulting from exposure to silica dust, there is an additive effect of inhalation of silica dust and cigarette smoking on clearance rates of 99mTc-DTPA.
Asunto(s)
Polvo/efectos adversos , Pulmón/metabolismo , Exposición Profesional/efectos adversos , Dióxido de Silicio/efectos adversos , Fumar/efectos adversos , Adulto , Epitelio/metabolismo , Humanos , Permeabilidad , Fumar/metabolismo , Pentetato de Tecnecio Tc 99m/farmacocinéticaRESUMEN
A higher ventilatory drive evaluated by the inspiratory occlusion pressure (Poc) and a respiratory pattern characterized by smaller tidal volume (VT) and higher breathing frequency (f) was detected in patients with chronic obstructive pulmonary disease (COPD), in relation to normals. The purpose of this study was to identify the possible mechanisms involved in the development of hypercapnia in those patients, at rest and during exercise. We have studied 11 normocapnic (PaCO2 ( 45 mmHg) and 9 hypercapnic (PaCO2 > 45 mmHg) COPD patients. As expected, no difference in the ventilatory response and neural drive was detected between the two groups. However, the hypercapnic patients have higher values of serum HCO-3 and lower values of PaO2 at rest and values of the ratio dead volume to tidal volume (VD/VT) significantly higher at rest (0.67 vs. 0.55) and during exercise (0.54 vs. 0.38) in relation to normocapnic individuals. There was also a significant positive correlation at rest (r = 0.66*) and during exercise (r = 0.65*; *p < 0.05), between PaCO2 and VD/VT, identifying a decreased alveolar ventilatory efficiency, important in the development of hypercapnia in those patients. when the COPD patients were divided into two distinct groups (PaCO2 ( 40 and ( 50 mmHg), a respiratory pattern characterized by higher f and smaller VT was detected in the hypercapnic group during exercise. In conclusion, a higher VD/VT linked to alterations of the respiratory pattern (lower VT) and to inequalities of ventilation/perfusion (high V/Q areas), seems to explain the hypercapnia of our COPD patients, since the ventilatory response and neural drive were similar in normo and hypercapnic patients.
Asunto(s)
Humanos , Masculino , Prueba de Esfuerzo , Hipercapnia/etiología , Enfermedades Pulmonares Obstructivas/fisiopatología , Descanso , Enfermedades Pulmonares Obstructivas/complicaciones , Espirometría , Ventilación Voluntaria Máxima/fisiologíaRESUMEN
1. Pulmonary epithelial permeability (PEP) as evaluated by the clearance rate (K, %/min) of 99mTc-DTPA from lung to blood was measured in 4 groups of individuals: 10 normal controls; 10 smokers; 15 silica dust-exposed ceramic workers, 7 without chest X-ray alternations; and 8 with mild radiographic alterations, consistent with silicosis (small opacities of up to 1.5 mm diameter). 2. All subjects had normal pulmonary function tests. The mean clearance rates of smokers (3.0 %/min) and silica-exposed workers with X-ray changes (2.9 %/min) were accelerated compared to controls (1.2%/min) (P less than 0.05). Ceramic workers with normal X-rays had mean clearance rates (2.0 %/min) similar to controls. However, 3 of 7 (43%) had K values higher than the upper limit of the 95% confidence interval for the control mean. 3. Comparison of regional K (%/min) values with controls indicated faster clearance of 99mTc-DTPA in the upper lung regions of smokers. There was also increased clearance in the silicotic workers although of more uniform distribution over the lung regions analyzed. 4. Both smokers and ceramic workers exposed to a silica dust environment, with or without chest X-ray alterations, may show increased PEP compared to controls. As measurement of this parameter appears to be a sensitive index of lung injury, follow-up studies involving workers exposed to noxious dust are proposed to relate alterations in PEP to early silicosis and to the extent of lung injury.
Asunto(s)
Permeabilidad Capilar , Pulmón/metabolismo , Silicosis/metabolismo , Fumar/efectos adversos , Cerámica , Humanos , Pulmón/diagnóstico por imagen , Compuestos Organometálicos , Ácido Pentético , Cintigrafía , Pruebas de Función Respiratoria , Silicosis/diagnóstico por imagen , Pentetato de Tecnecio Tc 99mRESUMEN
The authors report a case of Guillain-Barrè syndrome (GBS) following a varicella infection in a 13 year-old boy. During his admission he developed respiratory insufficiency and dysautonomic events, as well as a severe sensitive peripheral neuropathy. Some aspects related to the etiology and pathogenesis of GBS are discussed.