No abstract

SummaryAnesthetized young rabbits were ventilated for 6 hr at 20 cm HzO peak airway pressure using air nebulized with water at 22OC (cold nebulized group, n = 11). at 36OC (warm nebulized group, n = 11) and humidified air at 36OC (warm humidified group. n = 10).Their biochemical status during ventilation and pulmonary morphology at autopsy were compared to those of ten control rabbits. Both nebulized groups had particulate water in the inspired air and water of condensation in the endotracheal tube.The rabbits ventilated with warm humidified air and the control group breathing spontaneously maintained their blood pressure and pHa within physiologic range. Rabbits ventilated with air nebulized with water at 22 and 36°C had a significant decline in mean blood pressure (% mm Hg -61 mm Hg in cold nebulized and 91 mm Hg -. 61 mm Hg in warm nebulized) and mean pHa (7.43 -. 7.23 in cold nebulized and 7.42 -+ 7.31 in warm nebulized).All rabbits in the control and warm humidified groups survived the study whereas 9 of 22 in the nebulized groups died before completion of study ( P < 0.005).Morphometric analysis revealed a significant increase in the mean vascular wall thickness in both nebulized groups of rabbits when compared to that in the control and warm humidified groups ( P < 0.05). The cold nebulized group also had significantly less air space and correspondingly more interstitial thickness and intraalveolar edema ( P < 0.05) compared to control and warm humidified groups. ~h e s e findings of bulmonary parenchymal damage in rabbits ventilated with air containine oarticulate water and the -.greater degree of both physiologic and anatomic change evident in the cold nebulized animals suggest that particulate water and low inspired air temperature may contribute to the genesis of pulmonary damage during intermittent positive pressure ventilation. SpeculationThe phenomenon of reflex pulmonary hypertension following instillation of small quantities of fresh water to the lung (5) might occur even if miniscule amounts of particulate water are delivered during intermittent positive pressure ventilation. Particulate water in inspired air could therefore play a role in the pulmonary parenchymal damage seen in babies treated with intermittent positive pressure ventilation. Failure to maintain temperature of the inspired air at body temperature during intermittent positive pressure ventilation (25) may also have a deleterious effect in the human infant.The observations made by Northway et al. (29) in humans and deLemos el al. (7) in lambs suggest that use of high concentrations of oxygen during intermittent positive pressure ventilation (IPPV) is responsible for parenchymal changes seen in lungs of humans subjected to IPPV. More recent studies suggest that barotrauma may be a contributing factor (36. 37). In a previous study. we demonstrated lesions similar to those described by deLemos et al.

A system for screening cervical cytological preparations is described which employs the Leitz Texture Analyzer System (E. Leitz, Rockleigh, N. J.) quantitative staining with acridine orange, and a fluorescence standard. The instrumentation scans cells on microscope slides and detects objects which it interprets to be nuclei with excess total nuclear green fluorescence intensity (Previous results employing manual measurements have indicated that normal nuclei do not produce total nuclear green fluorescence greater than a specific absolute intensity level). Detected objects are identified by visual observation. Cells (102,000) from 65 patients (29 normal, 36 abnormal) have been examined. In each abnormal sample, at least one abnormal cell was detected. In over half of the samples, three or fewer other objects (e.g. clumps of polymorphonuclear leukocytes) were detected. These are easily distinguishable from single nuclei, and could be discarded by someone with minimal cytological training.

The irreversible photochemical fading of fluorescence of acridine orange-heparin complexes indicates that fading involves the reaction of a "reactive" excited bound dye dimer with one in the ground state. A kinetic parameter, r", is derived, which has a constant value over a considerable range of conditions, and which is directly related to rate constants for photophysical and photochemical processes. This parameter appears to be characteristic for heparin and may serve to identify it in the presence of other glycosaminoglycans.