[Alveolar recruitment under high-pressure transpulmonary inflation. An experimental morphometric study]. / Reclutamiento alveolar por insuflación transpulmonar a alta presión. Estudio morfométrico experimental.

We describe an experimental study in which morphometric techniques are used to question traditional conceptions about the behavior of the alveolus under changes in pressure. An increase in inflation pressure in the lung results in alveolar recruitment (an increase in distal air spaces) due to stretching of its walls. To test this hypothesis, the lungs of rats were filled to 25 to 35 cm water pressure. Lungs filled to a higher pressure were expected to present a decrease in alveolar size along with thinning of its walls, and an increase of internal perimeter of the alveolus with no change in amount of tissue. Morphometric data were processed by computer and results were analyzed by statistical tests. The lungs of 10 Wistar rats were examined under light microscope. The following variables were recorded: mean linear intersection (Lm), alveolar cord, wall thickness, internal alveolar perimeter and tissue percentage. Lower Lm in lungs filled to 35 cm water pressure allows us to consider that the number of alveoli increased; lower Lm and alveolar cord indicate that alveolar size is smaller; alveolar wall thickness decreased; internal alveolar perimeter increased. All these differences were statistically significant (p < 0.001), tissue percentage being the only variable that did not change significantly. All results lead us to consider that an increase in lung inflation pressure leads to alveolar recruitment and stretching of its walls.

[Morphometric assessment of rat lungs insufflated with liquid fixative at different pressures close to total lung capacity]. / Valoración morfométrica de pulmones de rata insuflados con líquido fijador a diferentes presiones próximas a la capacidad pulmonar total.

INTRODUCTION: Liquid lung fixing through the trachea to a pressure of 25 cmH2O is currently accepted to be ideal. However, some studies do not seem to confirm that assumption. MATERIAL AND METHODS: The lungs of Fischer rats were filled with fixing liquid to four different pressures: 20 cm, 25 cm, 30 cm and 35 cmH2O. The fixed lungs were processed for inspection under a light microscope for morphometric study. The following variables were recorded: lung volume, tissue volume, air volume, internal alveolar surface (IAS), alveolar chord to measure the size of the distal air space, and the number of alveoli. Statistical comparisons were performed. RESULTS: Lung volume increased with insufflation pressure, with significant differences related to pressure increases from 20 cm to 25 cm and from 30 cm to 35 cmH2O. Air volume did not change, although tissue volume changed when pressure increased from 20 cm to 30 cmH2O and from 30 cm to 35 cmH2O. The increase of tissue volume was related to extravasation of interstitial fixer. The number of alveoli increased with pressure from 20 to 30 cm and from 30 to 35 cmH2O. IAS increased with pressure from 20 cm and all the other pressures. Alveolar chord, which is related to size of alveoli, decreased significantly as pressure increased from 20 cm to 25 cm. CONCLUSION: A pressure of 25 cmH2O is ideal for liquid fixing of lung volumes. With lower pressures the lung is partially distended and with higher pressures the fluid can pass into the interstitial space.

[Usefulness of the quantification of (99M)Tc-MIBI uptake in breast neoplasms in the preoperative assessment of tumor aggressiveness]. / Utilidad de la cuantificación de la captación de (99m)Tc-MIBI en neoplasias mamarias en la valoración preoperatoria de la agresividad tumoral.

UNLABELLED: (99m)Tc-MIBI has been proposed as an imaging diagnostic method in a large variety of human malignant tumors. At present, the mechanism by which (99m)Tc-MIBI is uptaken and concentrated by the malignant cells is not totally known. Some mammary neoplasms do not show any uptake of (99m)Tc-MIBI. This study aims to determine if there is any correlation between the uptake of (99m)Tc-MIBI by the tumor and the different histopathological parameters involved in tumoral aggressiveness. To do so, we have studied 100 patients with breast cancer. All of them underwent a breast scintimammography with (99m)Tc-MIBI with semiquantitative analysis by means of a tumor-to-background ratio calculated in every projection. After surgery, an experienced pathologist determined tumor size, axillary lymph node metastases, histological grade (Scarff Bloom Richardson) (SCBR), nuclear grade, mitotic index, presence of cellular atypia and estrogen and progesterone receptor expression. RESULTS: A statistically significant correlation (p < 0.005) has been found between tumor-to-background (T/B) ratios of (99m)Tc-MIBI uptake and tumor SCBR histological grade. A correlation between (99m)Tc-MIBI uptake and the mitotic index, cellular atypia and nuclear grade has also been found. No correlation was found in our study with tumor size, hormone receptor expression or axillary lymph node metastases. CONCLUSIONS: (99m)Tc-MIBI uptake in breast cancer is correlated with the tumoral differentiation grade: the smaller the tumoral cellular differentiation (greater aggressiveness), the greater the uptake. On the other hand, no correlation was found between the uptake of (99m)Tc-MIBI and the classical pathological parameters that define tumoral aggressiveness, such as size and axillary lymph node metastasis.