Joseph W. Baker

Inhibition of atherosclerosis associated with reduction of arterial intramural stress in rabbits.

Atherosclerotic lesions commonly develop at arterial branch sites, which are also the sites of high arterial Intramural stress produced by Intralumlnal pressure. We Investigated the effect of reduced Intramural stress on the development of atherosclerotic lesions. We exposed the origin of the left renal artery In five rabbits and the aortic bifurcation in another five, lowered the mean arterial pressure to 35 to 45 mm Hg, and poured a dental acrylic liquid around the branch to form a rigid cast When the rabbits recovered and the arterial pressure Increased to normal, the casts prevented the arteries from expanding, thereby maintaining a low Intramural stress. These rabbits plus two unoperated, two sham-operated, two with silicons rubber casts placed at similar pressures, and four with casts placed at 95 mm Hg pressure were given a 2% cholesterol-enriched diet for 7 to 11 weeks, and then their arteries were examined. In all rabbits, atherosclerotic lesions developed at the origins of the Intercostal, cellac, superior mesenterlc, and both renal arteries, and at the aortic bifurcation, with these notable exceptions: no lesions developed at the origins of casted renal arteries or at the casted aortic bifurcations when the cast was placed at a low pressure. Measurements of the diameter and thickness of the aorta In the left renal branch and aortic bifurcation areas, with and without the casts, indicated that there was no significant narrowing of the aortic lumen or thinning of the aorta due to the cast In conclusion, the Inhibition of the development of atherosclerotic lesions appears to be associated with the reduction of arterial Intramural stress.

Reduction of Perioperative Hemorrhage by Anterior Mediastinal Spray Application of Fibrin Glue during Cardiac Operations

A variety of published techniques for the production of concentrated fibrinogen from units of screened single-donor human plasma have led to increasing clinical use of fibrin glue in the United States. We have adapted a method of applying this material with a disposable plastic sprayer. In 20 consecutively treated patients, fibrin glue was sprayed on the anterior mediastinum before closure of the median sternotomy incision. A control group of 20 patients undergoing the identical cardiac operations (13 coronary artery bypass grafting procedures [CABG], 4 valve replacements [including 1 reoperative procedure], and 3 combined valve replacements and CABG) by the same surgeon within a one-year period was chosen for comparison of chest tube outputs. Specifically, chest tube outputs were as follows for treated and untreated patients, respectively: at 12 hours, 461 +/- 40 ml (mean +/- 1 standard error of the mean versus 731 +/- 80 ml; at 24 hours, 714 +/- 73 ml versus 1,016 +/- 109 ml; and at 48 hours, 863 +/- 93 ml versus 1,187 +/- 137 ml. The differences between control and spray chest tube output are statistically significant by unpaired t test (p less than 0.05) at both 12 and 24 hours. Thus, this method can reduce perioperative hemorrhage from the anterior mediastinum after cardiac operations.

A Technique for Spray Application of Fibrin Glue During Cardiac Operations

Fibrin glue can be a useful adjunct to hemostasis in surgical patients. An effective technique for spray application of fibrin glue during cardiac operations is described.

Mediastinal fibrin glue: Hemostatic effect and tissue response in calves

There is continued controversy regarding the effectiveness and potential adverse effects of fibrin glue. Thus, we chose to evaluate it in a model of experimental calf aortic valve replacement that has been previously well established. Concentrated fibrinogen and topical thrombin were sprayed to form a thin layer of fibrin glue over the mediastinal tissues of 20 consecutive calves undergoing aortic valve replacement. Chest tube outputs of these animals were compared with those of the preceding 20 consecutive calves undergoing aortic valve replacement without fibrin glue. All procedures were performed by the same surgeon, and no other technical changes were made between the two series. Total postoperative chest tube output (mean +/- standard error) was 553 +/- 50 mL for the calves treated with fibrin glue and 1,155 +/- 103 mL for the control calves (p less than 0.001). On histological examination of mediastinal tissues from 5 treated calves killed 6 weeks after operation, there was no evidence of inflammation, fibrosis, or residual fibrin. To our knowledge, this is the first controlled laboratory study to show that fibrin glue spray is an effective hemostatic agent and that it produces no long-term tissue reaction.

The reversal of amiodarone-induced perioperative reduction in cardiac systolic reserve in dogs

There is controversy about the myocardial depressant effects of amiodarone in patients with decreased cardiac function undergoing surgery. Some surgeons believe that these effects complicate the discontinuation of cardiopulmonary bypass. Accordingly, the hemodynamic effects of amiodarone were evaluated in two groups of anesthetized mongrel dogs that had undergone a median sternotomy. A control group of 10 dogs and an amiodarone-treated group (15 mg/kg per day for 3 weeks) of 10 dogs were studied, and serum (0.26 to 1.09 micrograms/ml) and tissue (cardiac 2.97 to 11.60 micrograms/ml) levels of amiodarone were measured by liquid chromatography. Hemodynamic measurements were made at baseline and after administration of routine therapeutic intravenous doses of dobutamine (10 micrograms/kg per min), isoproterenol (0.06 micrograms/kg per min) and epinephrine (2 micrograms/min). The amiodarone-treated dogs had a smaller increase in cardiac output compared with baseline than did control dogs. For each drug when the amiodarone-treated group was compared with the control group, increases in cardiac output (liters/min) were: dobutamine, 1.32 +/- 0.24 versus 1.73 +/- 0.31; isoproterenol, 0.84 +/- 0.26 versus 1.43 +/- 0.28; epinephrine, 0.25 +/- 0.15 versus 0.44 +/- 0.53. Amiodarone-treated dogs were also given higher doses of drugs, dobutamine (50 micrograms/kg per min), isoproterenol (1.2 micrograms/kg per min) and epinephrine (20 micrograms/min). Increases in cardiac output were 1.24 +/- 0.24, 1.62 +/- 0.25 and 2.82 +/- 0.64, respectively. All cardiac outputs were significantly increased from the baseline values (p less than 0.05) except those measured in the amiodarone group receiving the lower dose of epinephrine. Thus, amiodarone-treated dogs have a relative reduction of perioperative cardiac systolic reserve.(ABSTRACT TRUNCATED AT 250 WORDS)

Successful treatment of postoperative chylothorax using an external pleuroperitoneal shunt

We report 3 patients with chylothorax who were successfully managed as outpatients using external pleuroperitoneal shunts. This external shunt has the advantage over subcutaneously placed shunts of pumping large volumes of fluid with each compression of the pumping chamber, of not causing the discomfort associated with pumping a subcutaneous chamber, of not becoming difficult to find in the subcutaneous space, and of being constructed of larger components which do not kink or become easily clogged with fibrinous debris.

Change in endothelial cell morphology at arterial branch sites caused by a reduction of intramural stress

Arterial branch sites have very high intramural stresses at physiologic intraluminal pressures; the same sites have a predilection for atherosclerosis. The effect of intramural stress on endothelial cell morphology was investigated. Five rabbits had permanent casts placed around a segment of the abdominal aorta-left renal artery branch area during controlled hypotension, thus reducing intramural stress without narrowing the lumen. These five animals, and three normal rabbits, were sacrificed after 4-8 weeks, and the vessels were perfused with buffered 2.5% glutaraldehyde for 2 h at 100 mm Hg pressure. The aortas were examined by scanning electron microscopy. In normal aortas, the distal region of the ostia of the left renal and celiac arteries just beyond the flow divider displayed many morphologically altered endothelial cells ranging from spindle shape to cobble-stone shape. The same aortic area of casted rabbits, as well as the straight abdominal aorta in all rabbits, showed a smooth surface of endothelial cells with intact cell borders and no morphologically altered cells. At branch sites, the occurrence of morphologically altered endothelial cells may be due to increased intramural stress. When intramural stress is reduced, the morphology of branch endothelial cells changes to resemble that of the unbranched regions. In conclusion, endothelial cell morphology changes in response to changes in intramural stress.

Pleural anesthetics given through an epidural catheter secured inside a chest tube

Pain management after thoracic surgical procedures is a difficult clinical problem. A variety of pain management methods are used with variable efficacy. This paper presents an effective method of pleural anesthetic administration using a pleural catheter inserted through a chest tube.