However, these studies may not reflect the extent of lung injury after milk product aspiration in the clinical setting because most fluids that are aspirated have been acidified after mixing with gastric fluid secretions. When we instilled 0.4 ml *symbol* kg sup -1 breast milk at its native pH level (6.6–7.4) into rabbits' lungs, we found no evidence of lung injury. More recently, Olson concluded that Similac (3 or 4 ml at its native pH level) injured rabbits' lungs to a greater extent than did distilled water. He also noted, however, that while smaller volumes of both human breast milk and cow's milk (3 or 4 ml) were not fatal, they did induce acute and delayed reactions in the lungs as evidenced by the presence of red cells, granulocytes, and macrophages. Moran reported that large volumes of milk products and hypertonic milk products at their native pH levels were often acutely fatal when instilled into the tracheas of rabbits. Previous studies of the pulmonary effects of the intratracheal instillation of milk products in rabbits identified several factors that predisposed to severe lung injury and/or death. The third issue and the least understood of the three, is the severity of lung injury that can be expected if milk products were aspirated. On the basis of these data, the fasting interval after breast milk is distinct from and should be greater than that after clear fluids if we intend for the stomach to be emptied of these products by the time anesthesia is induced. These data are supported by a report of large residual volumes of breast milk in the stomachs of infants who were fasted only 2 h before elective surgery. The rate of gastric emptying of breast milk is approximately one fifth that of water but twice as fast as infant formula. Few studies have addressed the rate of gastric emptying of milk products. The common milk products used in infancy are breast milk and infant formulas (such as SMA Wyeth, Windsor, Ontario). Your enquiry has been submitted.To develop meaningful fasting guidelines after ingestion of milk products, three issues must be addressed: first, a definition of milk products second, the rate of gastric fluid emptying and third, the severity of lung injury after aspiration of milk products. Please ask permission if you wish to re-use any of this website's content. Maker's Mark Leitz Wetzlar (on box) Specifications Materials Silk, glass, hair, brass, base metal, Weight 771 gms Size 90 × 110 × 420 mm © 2022 Phisick. Item History Date 1890-1930 Origin Germany Maker Leitz Wetzlar This instrument would have been used to determine refraction rather than used for fundoscopy per se which is why there are no retinal images. There is an eye of similar configuration shown in the Wellcome Images but with a painted background which is dated there as 1840-1900 Their lenses were world class and of the highest quality. Leitz Wetzlar were a German company formed in the late 19th Century who made microscopes and later cameras into the 20th century. The ring is set on an adjustable rod which is secured on a round brass pedestal. Lenses of various focal lengths and different mountings are contained in a separate case. The eye and lenses can be removed and is composed of two brass hemispheres which screw into each other, one of which is plated and has a central glass covering representing the cornea. The eye itself is mounted in a brass ring which on the front side is lined with silk and set in an orbit which is quaintly framed with upper and low eyelashes made from human hair which gives the model a surreal appearance and an amulet like quality. A beautiful antique German schematic eye.
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