George D. Zuidema

Aspiration pneumonia: Results of treatment by positive-pressure ventilation in dogs

Abstract Unilateral right-sided pneumonia was produced in dogs by instilling hydrochloric acid into the right main stem bronchus. Untreated animals survived an average of 4 days following aspiration before dying of respiratory failure. Animals treated with immediate positive-pressure ventilation all survived. If treatment with a respirator was delayed for twenty-four hours after aspiration, survival was identical to that of the untreated controls. Pulmonary scans revealed that irreversible changes had probably taken place in the pulmonary circulation of those untreated animals that did not survive, despite occasional clearing of pneumonia radiographically.

Aspiration pneumonia: A clinical and experimental review

Abstract The history, clinical features, pathophysiology, and treatment of aspiration pneumonia have been briefly reviewed. Emphasis has been placed on the discussion of the aspiration of liquid gastric contents of low pH. Comments have been made on the efficacy of present therapy and areas of future clinical and experimental investigation explored.

Functional Evaluation of Esophageal Reconstructions

Abstract The fundic patch and colon interposition operations have been evaluated clinically and experimentally using manometric, pH reflux, acid clearing, and cinefluoroscopic techniques. The data indicate that the fundic patch operation is an adequate operation for the prevention of reflux only when combined with a Nissen fundoplication. Long-term results of leaving a diseased segment of esophagus have not been determined. Clinically and experimentally, colon interposition for benign esophageal stricture has proved an effective operation for the prevention of reflux and recurrent stricture. Rather than acting as a passive conduit for the passage of food into the stomach, the colon exhibits peristalsis that can be characterized as the Type II contraction previously described for the colon in normal position. The prevention of reflux and maintenance of neutral colonic pH seem to depend upon the ability of the colon periodically to evacuate its contents, respond vigorously to acid, and act as a valvular mechanism against reflux when an intraabdominal segment of colon is present.

Changes in portal circulation after biliary obstruction in dogs

Summary Eighteen mongrel dogs were studied before and at three and four week intervals after common bile duct ligation in regard to changes in results of hepatic function tests and histology, portal pressures, and the degree of portasystemic shunting of differently labelled 15 ± 5 and 25 ± 5 μ particles injected into the portal vein. The demonstration of sinusoidal dilatation and increased intrahepatic portasystemic shunting at the 15 μ level in the majority of dogs by the fourth week of biliary obstruction, and its correlation with changes in portal pressure, are discussed in the light of the irreversible decreases in effective liver blood flow previously reported by one of the authors.

The effect of biliary obstruction on hepatosplanchnic blood flow in dogs

Abstract The response of hepatosplanchnic and other regional blood flows to CBD ligation has been studied after 1 and 2 weeks of biliary obstruction by the fractional distribution of differently labeled 25-μ carbonized microspheres injected into the left atrium. After 1 week of biliary obstruction, there was a generalized increased in effective liver blood flow and its hepatic arterial and portal venous components. The increase in the latter reflected an increase in arterial inflow to all the individual splanchnic viscera which was least in the colon. By 2 weeks, these changes had essentially returned to preoperative levels, with the exception of splenic flow. Coincident with these changes was an apparent increase in systemic arteriovenous shunting, the site of which was not determined. Possible causes underlying this early hepatosplanchnic response to biliary obstruction are discussed.

Aspiration pneumonia: Pulmonary arteriography after experimental aspiration ☆ ☆☆

Abstract Changes in the pulmonary arterial tree after experimental aspiration pneumonia have been followed in the dog. Pulmonary arteriography demonstrated marked vasospasm and thrombosis of branches of the pulmonary artery 6 hours after aspiration in untreated animals. In animals treated by immediate positive-pressure ventilation for 6 hours after aspiration, these vascular changes did not occur. It is suggested that these vascular changes may be important events in the pathogenesis of aspiration pneumonia.

The Study on Surgical Services for the United States (SOSSUS) and its Impact on American Surgery

The effects of SOSSUS can be fairly judged to be highly significant. Although it is too early to determine its ultimate effect on the number of board-certified surgeons and the number of individuals in training, it is important for having drawn attention to the consideration of many aspects of the delivery of surgical care and surgical education and for having stimulated similar studies by other medical and surgical specialties. It is hoped that such subjects will continue to be studied.

Intraperitoneal xenon for the detection of early intestinal ischemia: Effect of ascites, adhesions, and misdirected injections

Significant delay in the washout of intraperitoneal xenon (133Xe) in rats and dogs with decreased splanchnic blood flow (bowel strangulation, superior mesenteric artery and vein occlusion) has been previously demonstrated as the basis for radionuclide imaging to detect early (prenecrotic) intestinal ischemia. In this study, the effect of ascites, adhesions, and misdirected injections on the validity of this technique is evaluated. Xenon-133 (0.6 mCi) in 3 ml saline was injected into the peritoneal cavity of anesthetized rats and the washout of gamma activity monitored externally for 90 min. Gamma camera images were obtained at 30-min intervals. After 60 min, only 12 +/- 2% of injected activity remained in the controls. Sham operation (13 +/- 1%) and simple obstruction (12 +/- 2%) had been previously shown not to significantly slow washout, but segmental strangulation had done so dramatically (32 +/- 2%, P less than 0.0001). In these experiments, ascitic fluid (Ringers lactate) in volumes of 10 ml (13 +/- 1%), 20 ml (13 +/- 1%), and 40 ml (13 +/- 1%), did not significantly slow washout in nonischemic rats. Sixty and eighty milliliters produced very tense ascites and slight but significant delay in washout (14 +/- 1%, 17 +/- 1%, respectively, P less than 0.05). Moderate (11 +/- 1%) and severe (11 +/- 1%) adhesions produced by serosal scarification did not delay washout nor affect imaging. Injections of isotope intentionally misdirected into the abdominal wall (32 +/- 2%), bowel wall (18 +/- 1%), and bowel lumen (19 +/- 2%), each significantly (P less than 0.001) slowed washout. However, such misdirected injections were easily recognizable as such on the 1-min gamma camera images and could thereby be excluded as artifactual. Therefore, no false positive readings were obtained. It is concluded that the intraperitoneal xenon technique is not invalidated by mild to moderate ascites nor by moderate to severe adhesions. Misdirected injections produce invalid studies that are recognizable as such and thus are not misinterpreted. This approach should therefore be applicable to most patients with suspected intestinal ischemia.