Hyperpolarized gas diffusion MRI of biphasic lung inflation in short- and long-term emphysema models

During lung inflation, airspace dimensions are affected nonlinearly by both alveolar expansion and recruitment, potentially confounding the identification of emphysematous lung by hyperpolarized helium-3 diffusion magnetic resonance imaging (HP MRI). This study aimed to characterize lung inflation over a broad range of inflation volume and pressure values in two different models of emphysema, as well as in normal lungs. Elastase-treated rats ( n = 7) and healthy controls ( n = 7) were imaged with HP MRI. Gradual inflation was achieved by incremental changes to both inflation volume and airway pressure. The apparent diffusion coefficient (ADC) was measured at each level of inflation and fitted to the corresponding airway pressures as the second-order response equation, with minimizing residue (χ2 < 0.001). A biphasic ADC response was detected, with an initial ADC increase followed by a decrease at airway pressures >18 cmH2O. Discrimination between treated and control rats was optimal when airway pressure was intermediate (between 10 and 11 cmH2O). Similar findings were confirmed in mice following long-term exposure to cigarette smoke, where optimal discrimination between treated and healthy mice occurred at a similar airway pressure as in the rats. We subsequently explored the evolution of ADC measured at the intermediate inflation level in mice after prolonged smoke exposure and found a significant increase ( P < 0.01) in ADC over time. Our results demonstrate that measuring ADC at intermediate inflation enhances the distinction between healthy and diseased lungs, thereby establishing a model that may improve the diagnostic accuracy of future HP gas diffusion studies.

Balloon tamponade for the management of postpartum uterine hemorrhage

To evaluate the use of the Bakri balloon in postpartum hemorrhage (PPH) resistant to medical treatment.The Bakri balloon was applied to 45 women with PPH after failure of initial management. Bilateral internal iliac artery ligation (BIIAL) and hysterectomy were performed if necessary.The Bakri balloon was applied in 45 women; an additional BIIAL was required in nine women. The mean inflation volume of the Bakri balloon was 571±264 mL (range: 240–1300 mL). Hemostasis was achieved in 34 (75.5%) women with the Bakri balloon alone, and in six women with an additional BIIAL. The Bakri balloon was effective with additional procedures overall in 40 of 45 (88.8%) women. In 34 women with uterine atony, the Bakri balloon was successful alone in 27 (79.4%) and with an additional BIIAL in 30 (88.2%) women. An inflation volume of >500 mL was necessary in 18 women with uterine atony.The Bakri balloon may be performed as a first line of treatment for PPH resistant to uterotonic agents, and can be used not only in tertiary centers but also in limited-resource centers. The inflation volume of the Bakri balloon should be adjusted according to the type of PPH; a volume exceeding 500 mL may be necessary in uterine atony.

Study on Floatability and Separation of High Ash and Difficult Floatable Coal

According to the actual demand of scare coal resources in our country, there is a vital significance in the study on strengthening separated process of high ash and difficult floatable coal. In terms of the limitations and deficiencies of process intensification and flotation efficiency at home and abroad, by means of experimental and analytical approaches, the surface properties of scarce coal slime separation process and process intensification were focused on in this paper. The association between mineral dissemination and variation during flotation process was also focused on. The superficial properties of difficult floatable coal slurry and the existing problems of the traditional reagents in the separating process of difficult floatable coal were analyzed. The reagents dosages suitable for coal slime with high ash were proposed. In the process, kerosene and octanol were respectively taken as collector and frother. The conclusions were obtained that kerosene dosage was 320g/t, Octanol dosage was 110g/t, flotation concentration was 100g/L, and inflation volume was 0.37m3/m2•min.

Respiratory system mechanics in sedated, paralyzed, morbidly obese patients

Pelosi, P., M. Croci, I. Ravagnan, M. Cerisara, P. Vicardi, A. Lissoni, and L. Gattinoni. Respiratory system mechanics in sedated, paralyzed, morbidly obese patients J. Appl. Physiol. 82(3): 811–818, 1997.—The effects of inspiratory flow and inflation volume on the mechanical properties of the respiratory system in eight sedated and paralyzed postoperative morbidly obese patients (aged 37.6 ± 11.8 yr who had never smoked and had normal preoperative seated spirometry) were investigated by using the technique of rapid airway occlusion during constant-flow inflation. With the patients in the supine position, we measured the interrupter resistance (Rint,rs), which in humans probably reflects airway resistance, the “additional” resistance (ΔRrs) due to viscoelastic pressure dissipation and time-constant inequalities, and static respiratory elastance (Est,rs). Intra-abdominal pressure (IAP) was measured by using a bladder catheter, and functional residual capacity was measured by the helium-dilution technique. The results were compared with a previous study on 16 normal anesthetized paralyzed humans. Compared with normal persons, we found that in obese subjects: 1) functional residual capacity was markedly lower (0.645 ± 0.208 liter) and IAP was higher (24 ± 2.2 cmH2O); 2) alveolar-arterial oxygenation gradient was increased (178 ± 59 mmHg); 3) the volume-pressure curve of the respiratory system was curvilinear with an “inflection” point; 4) Est,rs, Rint,rs, and ΔRrs were higher than normal (29.3 ± 5.04 cmH2O/l, 5.9 ± 2.4 cmH2O ⋅ l−1 ⋅ s, and 6.4 ± 1.6 cmH2O ⋅ l−1 ⋅ s, respectively); 5) Rint,rs increased with increasing inspiratory flow, Est,rs did not change, and ΔRrs decreased progressively; and 6) with increasing inflation volume, Rint,rs and Est,rs decreased, whereas ΔRrs rose progressively. Overall, our data suggest that obese subjects during sedation and paralysis are characterized by hypoxemia and marked alterations of the mechanical properties of the respiratory system, largely explained by a reduction in lung volume due to the excessive unopposed IAP.