Chu-Jeng Chiu

The pathophysiology of intramyocardial pressure and blood flow distribution—A surgical perspective☆

Abstract This review presents the recent advances in the study of intramyocardial pressure (IMP) and transmural coronary blood flow distribution. The evolution of the idea, and the current knowledge on this subject is summarized and critically analyzed. There is an increasing awareness that such information may shed light on the pathophysiology of a number of surgical conditions, including the hemorrhagic necrosis of the inner myocardium associated with shock, trauma and open heart operations. It may also have important implications in other surgical procedures such as the direct and indirect moycardial revascularization, counterpulsation, and coronary perfusion for open heart surgery or organ preservation. These problems, many still unexplored, are discussed in perspective.

Adenyl cyclase-cyclic AMP response during bowel obstruction

Abstract The massive intestinal secretion seen with cholera and other enterotoxins has been correlated with elevated mucosal adenyl cyclase and cyclic AMP levels. Bowel obstruction is associated with intestinal secretion, and it was of interest to investigate whether this secretion also involved an altered second messenger system. Sixteen rats were obstructed by tying a ligature around the mid-intestine. The bowel proximal to the obstruction showed decreased adenyl cyclase activity by 24 hr and decreased cyclic AMP levels by 48 hr. There was no change in sodium fluoride-stimulated adenyl cyclase activity, indicating normal functioning of the catalytic subunit of the enzyme. Thus, intestinal secretion seen during bowel obstruction is apparently not mediated in the same way as that of cholera, and the decreased adenyl cyclase activity may be ascribed to membrane alterations incurred by bowel distention.

Experimental aspiration pneumonia: Hemodynamics, ventilator and membrane oxygenator support

Abstract Cardiopulmonary hemodynamics were studied in anaesthetized mongrel dogs following massive aspiration. Severe hypoxia and acidosis, volume deficit, decreased cardiac output and increased pulmonary resistance were prominent findings, while overt left heart failure does not appear to play an important role in the early stage of aspiration pneumonia. The use of mechanical ventilator support, with added oxygen if needed, is associated with improved oxygenation, more stable hemodynamics and more prolonged survival. In situations where PPV is ineffective due to massive shunting of blood in the lung, effective oxygenation is possible using the membrane oxygenator.

A new method to study the healing dynamics of acute gastric erosions and its application on restrained rats.

Abstract The use of intravenous colloidal carbon particles to study the healing dynamics of acute gastric erosions in cold restrained rats is described. Application of this technique revealed that approximately one half of acute gastric erosions in cold restrained rats are completely healed by 5 days. Ninety percent healing is accomplished by day 10. Animals stressed, labeled with carbon and then restressed 8 days later developed acute gastric erosions randomly, without predilection to the sites of initial gastric mucosal damage. This would suggest that there are no anatomically predetermined sites for the formation of acute stress erosions in this model.

The roles of intraluminal chyme and vasomotor response in the pathogenesis of non-occlusive intestinal infarcts.

The purpose of this study is to clarify the role of intraluminal chyme and the splanchnic vasomotor reaction on the pathogenesis of non-occlusive intestinal infarcts. In 5 mongrel dogs, 3 types of intestinal loops were created. A cervical loop, which is a heterotopic autotransplant of a segment of intestine, contains no chyme and is disconnected from the splanchnic innervation. A Thiry-Vella loop simultaneously constructed in the abdomen is also devoid of intraluminal chyme, but is still innervated. The intestine-in-continuity possesses both splanchnic innervation and intraluminal chyme. Hemorrhagic shock was then induced and the morphological response of the three types of intestine examined. The results indicate that the cervical loop is least damaged, whereas both the Thiry-Vella loop and the intestine-incontinuity are both severely damaged. It is concluded that in the non-occlusive hemorrhagic infarction of the intestinal mucosa, the peculiar splanchnic vasomotor response plays the dominant role. The pathogenesis of non-occlusive intestinal infarcts and its clinical implications are discussed.

THE ROLES OF VENTILATION AND PERFUSION IN LUNG METABOLISM: SURGICAL IMPLICATIONS

The lung, like other viable organs, requires the adequate supply of oxygen and metabolic substrates for its functional and structural integrity. Therefore, we studied the metabolic and ultrastructural consequences in the canine lung following bronchial and/or pulmonary arterial occlusions. The results indicate that the lung can maintain its bioenergetic levels for 5 hours with either the ventilation or perfusion alone. Ultrastructural changes appear to precede metabolic alterations measured. When both the ventilation and perfusion were interrupted, rapid biochemical and structural deteriorations occurred, whereas the combinations of alveolar obliteration and hypoxemia, induced with low F102, produced intermediate damage. The implications of these findings on the pathogenesis and evolution of acute respiratory distress syndrome, on the lung preservation for transplantation, and on the rationale for membrane oxygenator support are discussed.

The Use of a Cholestyramine Glucose Solution to Prevent Vasopressin-Induced Gastric Erosions in Pigs

Abstract Selective intra-arterial vasopressin infusion produced moderate to severe gastric erosions in fasted, anesthetized piglets. Such erosions were prevented by the prophylactic intragastric administration of a cholestyramine glucose solution. The clinical implications of these findings in the management of patients receiving intra-arterial vasopressin infusion for upper gastrointestinal bleeding were discussed.