Macromolecules reduce abnormal microvascular permeability in rat limb ischemia-reperfusion injury

We studied the effect of iv administration of biodegradable macromolecules on microvascular permeability after ischemia-reperfusion injury in a rat gastrocnemius model. After 2 h of tourniquet ischemia of the rats' hind limb, groups of animals were given iv lactated Ringer's solution (RL), serum albumin 5%, or varying MW fractions of biodegradable macromolecules of hydroxyethyl starch (HES), glycogen, and dextran. At the conclusion of the 24-h reperfusion period, the rat gastrocnemius muscles were collected. Water and K+ differences between the ischemic and control muscles were compared. Rats given a 100,000 to 300,000-dalton fraction of HES had significantly decreased water content (5.1 +/- 3.4%) when compared to rats receiving RL (8.3 +/- 2.2, p less than .01), less than 100,000 dalton HES (8.3 +/- 3.2, p less than .05), less than 300,000 glycogen (7.9 +/- 2.5, p less than .01), or dextran 150,000 (8.3 +/- 1.5, p less than .05). Rats given 100,000 to 300,000-dalton HES also had significantly higher ischemic muscle K+ content as compared to the nontourniquet control (difference 14.2 +/- 9.7 mEq/g) than rats receiving any of the other solutions (range 32.5 to 39.3) except the 300,000 to 1,000,000-dalton fraction of HES. Regression analysis comparison of K+ difference to the histologic evaluation of the muscles on the criteria of polymorphonuclear infiltration and interstitial edema (0, best; 3, worst) had a Pearson correlation coefficient of r = .73. Reduction of abnormally increased microvascular permeability may be accomplished by the iv use of appropriate sized biodegradable macromolecules.     

Hydroxyethyl starch macromolecules reduce myocardial reperfusion injury.

We assessed the value of a fraction of hydroxyethyl starch (HES Pz) in reducing the myocardial reperfusion injury in a canine open-chest model in which 1 hour of left anterior descending coronary artery occlusion was followed by 24 hours of reperfusion. Three treatment infusions (5% of blood volume) were compared: Ringer's lactate, serum albumin, and HES Pz (70% of the macromolecules between 100,000 and 1,000,000 d). When compared with Ringer's lactate and albumin, HES Pz significantly reduced the ratio of 24-hour infarct size to pretreatment area at risk (3% vs 19% and 16%, respectively) and myocardial water content (0.5% vs 3% and 1%). Potassium content differences between injured and normal myocardium were significantly less in the infarct regions of animals receiving HES Pz. In the canine model, HES Pz reduced 1-hour myocardial ischemia reperfusion injury significantly.     

Aortocoronary Gore-Tex Graft: 18-Month Patency

Despite widespread success with Gore-Tex (polytetrafluoroethylene) vascular grafts in peripheral artery operations, very little use has been made of this material in aortocoronary bypasses. We present the case of a 61-year-old woman with a 6-month history of angina who was found to have no suitable saphenous vein available at operation and who therefore underwent Gore-Tex bypass grafting to the right coronary artery. Coronary angiograms made 6 months and 18 months postoperatively showed patency of the 6 mm Gore-Tex replacement graft as well as the internal mammary artery placed to the left anterior descending coronary artery.Although frequent follow-up and close observation are recommended in patients with aortocoronary Gore-Tex grafting, the unique design of this material has made it the best alternative for synthetic coronary bypass conduit in the absence of the saphenous veins, particularly when these veins are found to be inadequate only at the time of operation.     

Concomitant prophylactic inferior vena caval clipping.

Fatal pulmonary embolism is a common complication of any major surgery, especially in high risk patients. Experimental work in animals showed definite impairment of myocardial function after inferior vena caval ligation, but no changes after clipping. During the last four years, we have used concomitant vena caval clipping as a prophylactic measure in major abdominal vascular procedures. No added mortality or morbidity has occurred because of clipping per se and no deaths were due to pulmonary embolism. We recommend concomitant prophylactic clipping as an adjunctive procedure for all laparotomy patients who are prone to pulmonary embolism.