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Salvage of the injured spleen is important in the trauma patient. Loss of the spleen can result in both early and late infectious complications due to immunologic and phagocytic deficits. Splenic salvage techniques include the use of polyglycolic acid (PGA) mesh to wrap and tamponade the damaged and bleeding spleen. However, the use of mesh may increase the incidence of infection in the presence of intraperitoneal contamination. We examined whether mesh in the contaminated field increases the infection rate compared to splenectomy in a murine model. Sixty male Sprague-Dawley rats were divided into three groups of 20 each: splenectomy, splenic wrap with PGA, and control (with splenic mobilization). All rats were subjected to a standard inoculum of enteric bacteria at the time of celiotomy. Sixteen (80%) of the splenectomy rats, 10 (50%) of the PGA mesh wrapped rats, and four (20%) of the control rats expired (P < 0.5). In surviving rats, necropsy at 7 days demonstrated abscess formation in all four (100%) of splenectomy, four of 10 (40%) in PGA mesh wrapped, and two of 16 (13%) of control rats. All of the abscesses in the wrap group involved the mesh. Overall infection rates (including fatal peritonitis, abscess formation, and empyema) were 100% for splenectomy, 75% for PGA mesh wrapped, and 30% for control rats (P < 0.05). We conclude in this experimental model that the use of PGA mesh wrap does increase susceptibility to infection, but much less so than splenectomy in the presence of intraperitoneal contamination.

This study compares nerve repair following tissue expansion with nerve repair using an interposed graft in the rat. Group I had expansion conducted over 2 weeks at 40 mmHg. A 4 mm segment was excised from the lengthened nerve and repaired primarily. Group II had a 4 mm segment of nerve excised and then replaced as an interposition graft. Group III was sham-operated controls. Thirteen weeks postoperatively, all animals were evaluated using walking track analysis. Thirty-five rats finished the study: Eleven in group 1, 10 in group II, and 14 in group III. The Sciatic Functional Index (SFI) was calculated for each group as follows: group l, −57 ± 11 (mean ± standard deviation); group II, −59 ± 25; group III, −13 ± 6.5. The control group was significantly better than either experimental group (P < 0.01). The two experimental groups were not statistically different. Nerve repair following expansion allowed only one coaptation to be used. Functional results were the same as with interposition grafting. Repair by the expansion technique would eliminate the need to harvest a nerve graft, and the subsequent donor defect. © 1994 Wiley-Liss, Inc.

Elongation of peripheral nerves would facilitate the repair of peripheral nerve injuries. The purpose of this study was to determine the efficacy of nerve expansion and the effect of different levels of intraluminal expander pressure upon nerve conduction. A 2-mL Silastic expander was placed under one sciatic nerve of adult male rats. The other nerve served as a control. Electroneuromyography (ENMG) was done at the time of initial expansion in seven animals. At 40 mm Hg expansion pressure a significant change in latency was found with an increase of 17% +/- 5%. Expansion was carried out for 14 days in two groups of seven rats, group I at 20 mm Hg and group II at 40 mm Hg. Length gain on the expanded side was 30% in group I and 40% in group II. No significant changes in latency or velocity were found after expansion. We conclude that nerves can be expanded at low pressures with no significant conduction changes but long-term recovery of histologic changes needs to be evaluated.

This is a retrospective study designed to evaluate the pattern and severity of injuries that result from low falls, defined as falls from less than 20 ft, subsequent mortality, and requirements of hospital resources. Our hypothesis is that many of these injuries, even without cardiopulmonary instability, are worthy of trauma center care.The records of all patients entered into the hospital trauma registry at an urban Level I trauma center during the years 1991 through 1997 who suffered low falls and who either died after admission or were hospitalized for at least 3 days were reviewed. Patients suffering isolated hip fractures were excluded. One hundred seventy-six patients constituted the study population. This group accounts for about 2% of all admissions for falls at our institution. Patterns of injury were examined. Age, mechanism of injury, Injury Severity Score (ISS), and cardiopulmonary or neurologic instability on admission were documented. Mortality, length of intensive care unit and hospital stays, as well as billed hospital charges, were reviewed.The majority of patients (62%) were younger than 50 years. Sixty patients had ISS15 and 116 patients had ISS9. Sixty patients had multisystem injuries requiring specialty care. Head injuries were found in 81 patients (35%), and vertebral fractures or spinal cord injuries were found in 49 patients (22%), including 9 quadriplegics and 5 paraplegics. There were seven patients with intra-abdominal injuries (five spleen and two bowel injuries). There was one patient with a rupture of the thoracic aorta. Seventeen patients had deteriorating neurologic or pulmonary function on arrival, but the majority (90%) were stable. Of the 159 "stable" patients, 48 suffered head injuries, 7 were quadriplegic, and 3 were paraplegic. All intra-abdominal injuries were in this group. Overall, 14 of 176 patients (8%) died. Seven deaths were in patients older than 60 years, and seven deaths were in younger patients (p = 0.04). The majority of deaths (9 of 14) were from head trauma. Care in the intensive care unit was required in 92 of 176 patients. Nine patients had billed charges exceeding $100,000.Low falls can cause significant injuries, most commonly to the head and spine. Based on mechanism of injury alone, patients injured in low falls might not be taken to trauma centers. We have found, however, that many of these patients sustain serious multisystem injuries, even though they are stable initially. Although these patients represent only a fraction of those who fall, our study would support adjustment of triage guidelines to recommend transport of such patients, particularly elderly patients, to trauma centers.

A patient with a delayed aorto-right ventricular fistula and aortic valve injury after penetrating trauma is reported, and 17 similar additional cases from the literature reviewed. By examining the aortic root of adults with normal cardiac anatomy at autopsy, we defined the target area for these injuries as a 2 X 2 cm contact surface between the aorta above the right coronary cusp and the right ventricular outflow tract below the pulmonary valve. Five of the 18 patients required emergency exploration due to hemodynamic instability. Life-threatening sequelae (hemorrhage and cardiac tamponade) result from the external injury rather than the intracardiac component. Intracardiac damage is most commonly manifested as the delayed recognition of a cardiac murmur and some degree of congestive heart failure, and when these appear one must suspect intracardiac trauma. We recommend cardiac catheterization and elective repair, maintaining control of both ends of the intracardiac fistula with bolstered suture. Aortic valve injury can often be primarily repaired. Patients with combination aortic valve and aortocardiac fistula injuries, more so than those with a single intracardiac lesion, fail with nonoperative management. Of the 18 patients, 17 underwent surgery. One of these died: the others did well during short-term followup (less than 1 year).

Haemorrhagic shock was induced in anaesthetized, open-chest dogs by controlled arterial bleeding, sufficient to reduce and maintain mean arterial blood pressure at 40 mmHg for 30 min. The blood volume was then restored to the pre-shock level by rapid, intravenous reinfusion of the blood shed during the shock period. Haemorrhagic shock produced significant haemodynamic changes, characterized by a marked depression of myocardial function. Cardiac output (1226 +/- 57 ml min-1), peak aortic blood flow (6030 +/- 383 ml min-1) and maximum rate of rise of left ventricular pressure (2708 +/- 264 mmHg s-1) were all reduced by more than 50%. The haemodynamic profile was markedly improved by reinfusion of shed blood but this improvement was not sustained. There was a gradual decline such that 50% of the untreated animals suffered complete circulatory collapse and death between 60 and 120 min following reinfusion. Neither haemorrhagic shock, nor reinfusion of shed blood produced any consistent or significant changes in the myocardial adenine nucleotide pool. The ATP, ADP and AMP levels were, respectively, 25.9 +/- 4.2; 15.6 +/- 1.0; 4.3 +/- 1.9 nmol g-1 protein, before haemorrhagic shock; 21.6 +/- 3.4; 21.5 +/- 2.5; 10.2 +/- 2.7 nmol g-1 protein, after 30 min haemorrhagic shock; and 29.9 +/- 3.9; 16.5 +/- 1.2; 4.2 +/- 1.1 nmol g-1 protein, 60 min following reinfusion of shed blood. Pretreatment with allopurinol (50.0 mg kg-1 i.v.), 60 min before inducing haemorrhagic shock, had no significant effect upon the haemodynamic response to shock, but did prevent the gradual decline seen following reinfusion in the untreated animals. All of the allopurinol-treated animals displayed significantly better haemodynamic profiles than the untreated animals, furthermore, there was a 100% survival rate in this group. 5 Allopurinol had no significant effect upon the myocardial adenine nucleotide pool either during haemorrhagic shock or following reinfusion of shed blood.

IN RECENT YEARS, the role of nutrition in the management of surgical patients has been extensively reappraised. Patients undergoing major operative procedures, or those with burns or other major trauma, have nutritional requirements far in excess of what can be given with conventional intravenous fluid therapy. In an effort to meet these requirements, the use of total parenteral alimentation (TPA) has been investigated in a number of institutions.2,7'8'10'17'18'24 Between 1969 and 1971, a total of 102 patients have been given TPA at Vanderbilt University Hospital as an adjunct to surgical treatment of the underlying diseases (Table 1). The present communication summarizes what has been learned from this experience about the management of surgical patients with total parenteral alimentation using crystalline amino acids as the sole source of nitrogen.

venous thrombosis. The entity is simply defined. If one considers all instances of thrombosis of the mesenteric veins and subtracts those cases in which the thrombosis has an obvious cause, such as pylephlebitis, portal venous stasis, hypercoagulable states, or trauma, those remaining form a group which is defined as having no known cause. This group has variously been called primary mesenteric venous thrombosis,7 agnogenic venous mesenteric thrombosis,' and mesenteric venous occlusion of undetermined origin.2 Since this disease is defined in an entirely negative manner, the question arises as to whether it is a distinct clinical and pathologic condition or simply an accident of classification. Naitove and Weismann 7 recently reported three cases of their own and reviewed 34 collected from the literature. They concluded that there are certain characteristics which many cases shared and that the disease thus could be classed

Twenty-one patients with multiple organ failure were studied with hemodynamic monitoring. The five survivors were compared with the 16 nonsurvivors. Significant differences were found in the cardiac index (CI), the left ventricular stroke work index (LVSWI), and the pulmonary vascular resistance index (PVRI). The CI was higher in survivors (4.38 +/- 1.71) than in nonsurvivors (3.43 +/- 1.49). The LVSWI was also higher (43.0 +/- 16.8, 28.7 +/- 12.8) than in nonsurvivors (47.4 +/- 2.91). The PVRI was lower in survivors (168 +/- 122) than in nonsurvivors (474 +/- 291). It is postulated that the elevated PVRI in MOF is related to the adult respiratory distress syndrome.

This study was designed to test the hypothesis that the rapidity with which the heart rewarms following cold cardioplegic arrest depends upon the technique of cannulation. In dogs, temperatures were monitored at multiple myocardial sites during rewarming, using four different cannulation techniques: caval cannulation with total bypass, caval cannulation with partial bypass, atrioventricular cannulation, and atrial cannulation. A mathematical model was constructed to facilitate analysis of the data, assuming that the rewarming process can be described by first order kinetics. Using this model, the half time of rewarming was defined as the time required for the myocardium to rewarm halfway from initial temperature to core temperature. Analyzing the several cannulation techniques in terms of the half time of rewarming, several conclusions were drawn: myocardial temperature distribution is non-homogeneous, rewarming is relatively rapid, partial bypass produces more rapid rewarming than total bypass, atrioventricular cannulation produces more rapid rewarming than either caval or atrial cannulation, and the principle routes of rewarming were from the posterior parieties and from blood entering the right side of the heart during partial bypass.

Gastric suction has traditionally been available in three modes: continuous, sump, and intermittent. An intermittent air injection suction system (IAIS) has been developed in which small (20 to 30 mm) amounts of air are injected two to three times a minute. Very low (20 mm Hg) suction levels are applied. The hypothesis of the present study is that such a device will prevent suction-induced gastric mucosal damage, probably produced by suctioning of mucosa into the holes of the NG tube. IAIS should prevent this by physically expelling the mucosa out of the holes and allowing use of much lower suction levels. In 25 animals, gastric suction for 24 h in anesthetized dogs routinely produced ulcers. However, IAIS produced significantly fewer ulcers and in fewer animals. In 37 animals, the effectiveness of suction, measured by recovery of fluid instilled in the stomach, and the tendency of the tube to block were studied. Effectiveness was the same for all modes studied. Blockage was significantly less with IAIS.

A new fat emulsion for intravenous use, derived from safflower oil (Abbott Laboratories), was studied. The clotting mechanism was compared with a battery of tests performed during the infusion of total parenteral nutrition (TPN) using glucose alone and during infusion of TPN using both glucose and fat. Five adult surgical patients underwent TPN with 7.0 per cent amino acid solution for ten days, receiving glucose as their only nonprotein calorie source on days one, two, nine, and ten (40 kcal/kg/day). On days three through eight, 10 per cent fat emulsion (600-900 ml/day) was given each day to provide one-third of the nonprotein calories. Simplate bleeding time, prothrombin time, activated partial thromboplastin time, fibrinogen (Biuret method), platelet count, platelet aggregation, serum functional antithrombin, and viscoelastic curves were measured on days one, three, six, and ten. Some of these studies were abnormal at baseline and during the study. No significant changes were seen with fat emulsion infusion. The patients did not exhibit any evidence of clinical bleeding. This new intravenous fat emulsion did not appear to be associated with alterations in the clotting mechanism. However, two of five patients showed increases in serum triglycerides and one patient died during the study.

Most foreign bodies in the chest do their damage at the time of injury. While needle-like objects may migrate (6), delayed intrathoracic injury is rare. Delayed transthoracic penetration of the heart by a staple is reported, and is felt to be unique because acute hemopericardium resulted 30 days after the time of initial injury. The principles of recognition of pericardial tamponade, initial stabilization with periocardiocentesis, and immediate exploration are emphasized.

To evaluate a new low lint, nonwoven surgical sponge material, a prospective, stratified, randomized, single blind study of 232 patients was carried out. Patients studied underwent thoracic, upper abdominal or lower abdominal operations. The new material, in the form of laparotomy pads and sponges, was compared with cotton gauze. Safety of the material was evaluated by a battery of biochemical and hematologic tests. No clinically significant differences were seen. Effectiveness was evaluated by measuring fluid absorption. The new material was significantly more effective than cotton gauze in both configurations studied. Since this article was completed, the sponge material has been refabricated into laparotomy pads which are appreciably softer and more comformable than the study pads. The newest revision has been cleared by the Food and Drug Administration for clinical use.

Administration of total parenteral nutrition (TPN) solutions high in branched chain amino acids (BCAA) is thought to improve metabolic support during stress. This prospective, randomized, double blind study compared 45 per cent BCAA with 25 per cent BCAA in 12 patients. Seven patients had multiple trauma; two, gastrointestinal surgery; one, pancreatitis; and two, cirrhosis. The TPN regimen was 1.0-1.5 gm/kg/day amino acids and 30-45 glucose kcal/kg/day. The BCAA formula used was high in isoleucine and valine, but not leucine. Amino acid plasma levels, blood chemistries, 3-methylhistidine excretion, and nitrogen balance were studied. Control studies showed negative nitrogen balance (-7.1 +/- 2.9 gm) (mean +/- SEM), elevated insulin (61 +/- 21 microunit/ml), and elevated 3-methylhistidine (3MH) excretion (688 +/- 309 micromol); plasma leucine (93 +/- 11 nmol/ml) and isoleucine (37 +/- 23) were low, and valine (155 +/- 20) was elevated. Plasma methionine (40 +/- 9) and tyrosine (70 +/- 12) were high normal. Phenylalanine (85 +/- 5) was elevated. Both groups showed increased nitrogen excretion and positive nitrogen balance during the study (25 per cent, 2.0 +/- 1.4 gm/day; 45 per cent, 1.2 +/- 2.6 gm/day). Three-methylhistidine excretion changed little in either group (557 +/- 149, 414 +/- 91), insulin rose (135 +/- 27, 65 +/- 19), and plasma leucine (82 +/- 4, 71 +/- 9) changed little. Plasma isoleucine (51 +/- 3, 155 +/- 16) and valine (173 +/- 11, 691 +/- 23) both rose, more in the 45 per cent group. Methionine (67 +/- 12, 37 +/- 4) and tyrosine (51 +/- 6, 50 +/- 10) changed little.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum concentrations of amikacin following operative wound irrigation were studied in 17 patients having laporatomy and in eight patients having thoracotomy. Irrigation was done with 500 mg of amikacin in 200 ml of saline. The irrigant was reaspirated after 3 minutes. Measurement of amikacin in the irrigant allowed calculation of the retained dose. Serum levels were measured before surgery, and at 30 minutes, 60 minutes, 6 hours, and 12 hours following irrigation. Amikacin was assayed by a microbiological technique. The retained dose after peritoneal irrigation was 350 +/- 128 mg, and after pleural irrigation was 100 +/- 79 mg. The average maximum serum level in the peritoneal irrigation group was 9.4 +/- 6.7 gm/ml; in the thoracotomy group it was 3.5 +/- 1.7. Fourteen of the 17 laparotomy patients but only one of the eight thoracotomy patients had measurable plasma levels at 6 hours. Plasma half-life in the laparotomy group was 2.81 +/- 1.34 hours, and in the thoracotomy group 1.53 +/- 0.83 hours. Interoperative amikacin irrigation, even with immediate aspiration, results in significant absorption in both thoracotomy and laporatomy patients. There was less absorption and a shorter serum half-life in the thoracotomy patients.

Because clinical assessment of bowel viability is unreliable, other methods of determining intestinal perfusion have been recommended. Since none of these quantifies intestinal blood flow, we measured flow at the detection thresholds of Doppler ultrasound, photoplethysmography, and intravenously administered fluorescein, perfused the intestines at these threshold levels, and assessed histologic evidence of ischemic damage. The intestines of five anesthetized dogs were perfused for 4 hours via an in-line pulsatile extra-corporeal circuit assembled between the iliac and superior mesenteric arteries at either relatively physiologic (approximately 20 ml/min/kg body weight) levels or reduced levels representing the flow detection thresholds of Doppler ultrasound or photoplethysmographic probes (approximately 4 ml/min/kg). Intravenously administered fluorescein was detected at even lower perfusion levels (approximately 2.1 ml/min/kg). Clear-cut ischemic changes were documented histologically in all subjects perfused at Doppler/PPG flow detection thresholds but in none of those perfused at normal levels. We conclude that threshold blood flow detection by any one of these methods, especially fluorescein, occurs at levels inadequate to guarantee tissue viability.

A case of ruptured pheochromocytoma is presented, the pathophysiology discussed, and the literature reviewed. Evidence is presented that the use of alpha-adrenergic blockade in general, and phentolamine in particular, may predispose to this complication. Twelve cases of massive hemorrhagic necrosis with or without rupture were found in the literature, including the present case. Six had no operation; one survived. Six had immediate operation; 4 survived. An additional case of hemorrhage into a small pheochromocytoma following phentolamine is presented. This tumor was neither ruptured nor massively necrotic, but the case supports the hypothesis that alpha-adrenergic blockade may cause hemorrhage within the pheochromocytoma.

PHEOCHROMOCYTOMA and renal arterial stenosis are each important and surgically significant causes of hypertension. The combination of pheochromocytoma with renal arterial stenosis is rare, but it has been observed in a small number of patients. Table 1 lists eight such cases reported by other investigators.6' 7, 8, 16, 17, 19 Measurements of catecholamines and their metabolites are established criteria for diagnosis of pheochromocytoma.14 Recent reports from our laboratory 11 and by others 5 show that measurement of renal venous plasma renin activity is a useful diagnostic test in renovascular hypertension. If the ratio between renin activity in plasma from the side with anatomic stenosis and that from the opposite renal vein is 1.5 or greater, our experience indicates that the patient is likely to be relieved of hypertension or significantly improved by appropriate surgical correction of the lesion." It has further been shown.10,12 that assumption of an upright posture enhances renin plasma activity on the involved side far more than on the uninvolved side, and increases the ratio of the two. Studies of catecholamine and renal venous plasma renin activity were performed and were of assistance in the evaluation of a patient with the combination of left renal hilar pheochromocytoma and left renal arterial stenosis.