Resumen

PIVA, Jefferson Pedro; MENNA BARRETO, Sérgio Saldanha; AMANTEA, Sérgio  y  ZELMANOVITZ, Flávio. The use of helium-oxygen mixture in the ventilation study of children with chronic obstructive lung disease. Rev. bol. ped. [online]. 2002, vol.41, n.3, pp.145-153. ISSN 1024-0675.

Objective: To study the distribution of the radioaerosol of 99mTc- DTPA when the heliox gas is used as an inhalation vehicle during the pulmonary ventilatory scintigraphy in children and adolescents with chronic obstructive lung disease (COPD). Material and methods: Clinical randomized and controlled trial. Patients (from 5 to 18 years old) with COPD needing pulmonary scintigraphic study, between March 1996 and September 1998, were included. The obstruction of the lower airway was measured by pulmonary function study. The patients were randomized in two groups: heliox (helium 80% and oxygen 20%) or oxygen, according to the gas used as a vehicle to nebulize the particles during the scintigraphic study. The results of the scintigraphic study were expressed by the slope of the curve (the inclination of the curve of cumulative pulmonary radioactivity) and by the maximal cumulative radioactivity achieved in the lungs areas. The mean diameter of the 99mTc-DTPA particles generated by heliox and oxygen were measured by laser diffraction. Results: Ten patients were allocated in each group, without any statistical difference (p>0.05) in respect to gender, main diagnosis, signs of undernutrition, the mean values of weight, height, body area and the results of the pulmonary function study. The mean slope in the heliox group (5.039 +1.652) showed a significant difference (p=0.018) when compared to the mean slope of the oxygen group (3,410 +1,100). The patients with reduction of the airway flow in the heliox group obtained a mean slope with significant difference (p=0.017) when compared to the mean slope of the patients in the oxygen group with the same reduction in airway flow. The patients of the heliox group and oxygen group without airway obstruction flow did not show any statistical difference when they were compared on the basis of either the means of the slopes (p= 0.507) or the means of the cumulative radiation in the lung fields (p=0.795). The mean diameter of the particles of 99mTc- DTPA generated by heliox was 2.13 (+0.62mm), with a statistical difference (p=0.004) when compared with the mean diameter of the particles generated when oxygen was used as a vehicle (0,88 +0,99 mm). Conclusions: When heliox was used as a vehicle in the scintigraphic study of children and adolescents with DPOC, it showed a better distribution and dispersion of the 99mTc-DTPA into the lungs than that obtained when oxygen was used. The benefits of heliox over oxygen are more evident in the presence of lower airway obstruction flow. Without airway obstruction flow we could not demonstrate any difference in the distribution and in the radiation activity into the lungs. The mean diameters of the particles of 99mTc-DTPA generated by heliox and oxygen showed a significant difference. In spite of this, the mean diameters observed in both groups were included in the recommended range (between 1 and 5 mm). Therefore, the observed differences between the particles generated by both gases could not justify the effects of heliox demonstrated in this study.

Palabras clave : J. pediatr. (Rio J.) 2000; 76 (1): 17-26; helium; oxygen inhalation therapy; respiratory therapy; obstructive lung diseases; asthma; administration by inhalation.