Polypropylene mesh closure after emergency laparotomy: morbidity and outcome.

BACKGROUND: Alternative methods for abdominal wall closure may be necessary after emergency laparotomy. The purpose of this study was to determine the morbidity and outcome of emergency fascial closure with polypropylene mesh. METHODS: A retrospective review was performed of all patients undergoing emergency fascial closure with polypropylene mesh from January 1990 to March 1994. RESULTS: Seventy patients were identified. Indications for mesh placement included visceral edema (40), infected/necrotic fascia (21), and planned reexploration (7). Enteric fistulas developed in five patients (7.1%). When omentum was interposed between intestine and mesh, the incidence of fistula was significantly reduced (0 of 51 vs 5 of 19, p < 0.01). Forty-two patients (60%) survived with wound closure, accomplished by skin flaps in 19 (45%), skin grafting in 11 (26%), and secondary healing in 6 (14%). The mesh was removed in six patients (14%). Complications of mesh extrusion and hernia occurred less often after skin flap closure compared with skin grafting or secondary healing (1 of 19 vs 9 of 17, p < 0.01). No mesh infection occurred. CONCLUSIONS: Polypropylene mesh placement is an effective alternative for abdominal closure after emergency laparotomy, even when intraabdominal sepsis is present. Fistulas associated with its use may be effectively eliminated by the interposition of omentum between bowel and mesh. Wound closure with full-thickness skin flaps is the preferred method for soft tissue coverage when mesh is used.

Infrainguinal bypass in patients with end-stage renal disease.

BACKGROUND: This study was undertaken to evaluate the outcome of infrainguinal arterial reconstruction in a high-risk subset of patients with end-stage renal disease. METHODS: We reviewed the medical records of 44 patients requiring maintenance dialysis and undergoing 57 infrainguinal bypass procedures for limb salvage from 1986 to 1992. These included 16 (28%) femoropopliteal and 41 (72%) tibial or pedal bypasses with autogenous (82%), prosthetic (12%), or composite (6%) graft materials. The principal indications for operation were ischemic ulceration or gangrene (79%) and rest pain (21%). Angiographic evaluation most frequently showed single-vessel runoff (56%). Risk factors included age (mean, 63 years), diabetes (75%), hypertension (93%), coronary artery disease (52%), smoking (39%), previous myocardial infarction (20%), and contralateral amputation (18%). Infection was present in 22 limbs (39%). RESULTS: Early (30-day) surgical morbidity rate was 39%, including wound breakdown (19%), graft thrombosis (9%), and major amputation (4%). Perioperative mortality rate was 9%. Cumulative primary graft patency rates were 71% and 63%, secondary patency rates were 80% and 66%, and limb salvage rates were 70% and 52% at 1 and 2 years, respectively. Limb loss correlated most highly with the presence of preoperative infection (p = 0.036; log-rank method). Patient survival rate was 52% at 2 years. CONCLUSIONS: Life-table analysis confirms a poor life expectancy for this population but indicates that an acceptable level of limb salvage may be achieved with arterial reconstruction in properly selected patients.

Chronic alcohol ingestion increases aortic lipid levels in rats.

We evaluated the effects of alcohol ingestion on aortic lipid concentrations in 15 pair-fed Sprague-Dawley rats divided into three groups of five animals each. Control rats were fed a liquid diet, with 36% of their energy provided by maltose-dextrin for 28 days, and the remaining two groups of rats were fed an equivalent proportion of their energy as alcohol for 28 days or 18 months. Alcohol-fed rats exhaled significantly greater quantities of ethane than did controls at 28 days and 18 months. Serum cholesterol levels increased by 40% and triglyceride levels increased by 80%, but phospholipid levels remained unchanged in alcohol-fed rats compared with controls. Aortic concentrations of cholesterol and phospholipids increased twofold and threefold, respectively, in alcohol-fed rats, with a corresponding alteration of the cholesterol-phospholipid ratio at both time intervals. Tissue triglyceride levels were only elevated at 28 days, and no differences in aortic lipid peroxide levels were detected between alcohol-fed rats and controls. The results of the study indicate that alcohol ingestion increases aortic cholesterol, phospholipid, and triglyceride levels at 28 days and cholesterol and phospholipid but not triglyceride levels at 18 months. The mechanisms underlying the accumulation of lipids in aortic tissue need further elucidation.

Mature human atherosclerotic plaque contains peroxidized phosphatidylcholine as a major lipid peroxide.

The initial stage of atherosclerotic plaque formation involves oxidation of the phosphatidyl-choline moiety of low density lipoprotein (LDL) and subsequent uptake by macrophages. Ongoing uptake in developing plaque also may involve oxidized LDL and would require an oxidizing environment in plaque lipids. Atherosclerotic plaque lipids from 12 patients undergoing peripheral vascular procedures were extracted in chloroform: methanol (2:1). This extract was applied to a 25 cm 5 micron silica HPLC column and eluted with a ternary gradient mobile phase utilizing a laser light scattering (ELSD) mass detector. Individual lipid fractions were then analyzed. Cholesterol, both free and esterified, was the most prominent lipid in plaque (104 +/- 74 mg/gm tissue. However, lipid peroxides were present in much higher concentrations (3.52 +/- 2.84 FU X 10(4)/mg phospholipid) and overall level (21.27 +/- 10.10 FU X 10(4)/gm plaque) in the phospholipid component (*p< 0.05). Phosphatidyl-choline (PC) accounted for 63% of the total phospholipid peroxides recovered (6.31 +/- 5.09 mg/gm plaque; *p<0.05). PC and phosphatidylinositol (PI) content were linearly related to lipid peroxide fluorescence (PC; r=0.696; p=0.01) (PI; r=0.809; p=0.001). Lipid peroxides in human atherosclerotic plaque are present primarily in the phospholipid component and phosphatidyl-choline forms the bulk of these peroxides. PC may play an important role in ongoing plaque lipid accumulation.

Evidence for lipid peroxidation in atherosclerosis.

Lipid peroxidation may play a significant role in the initiation and progression of atherosclerotic plaque. Freshly harvested normal and atherosclerotic human aortic tissue, coronary arteries and explanted vein grafts were snap frozen at -70 degrees C. Folch reagent (chloroform-methanol 2:1, v/v) was used to extract lipids from the homogenates. These extracts were assayed for cholesterol, phospholipid and triglyceride content. Lipid peroxide complexes in vessels were measured fluorometrically. Atherosclerotic plaque from patients with aortic aneurysmal and occlusive disease and coronary artery disease contained significantly greater amounts of cholesterol (15.54 +/- 9.71 vs 3.39 +/- 1.14 mg/g tissue) than controls (p less than 0.01). Lipid peroxide fluorochromes were similarly elevated in all atherosclerotic tissue (4.159 +/- 1.065 vs 3.087 +/- 0.497 fluoro units/g tissue) compared to control (p less than 0.01) with significant elevations in saphenous vein grafts and occlusive aortic disease. Although lipid peroxidation and lipid accumulation occur in close association in atherosclerotic plaque, the role of lipid peroxides in the pathogenesis of atherosclerosis remains to be determined.

Is the increasing use of prophylactic percutaneous IVC filters justified?

To determine whether the ease of percutaneous inferior vena cava (IVC) filter placement has led to an alteration of procedural indications, we reviewed the medical records of 150 patients who underwent 156 filter insertions from January 1986 through June 1993. Thirty-nine Greenfield filters were surgically inserted, while 117 percutaneous devices were placed in 111 patients. A comparison of these two groups showed that they had similar thromboembolic risks. Indications for surgical filter placement included pulmonary embolism (PE) prophylaxis (23%), PE with a contraindication to anticoagulation therapy (28%), and complication (26%) or failure (20%) of anticoagulation therapy. Indications for initial percutaneous placement included PE prophylaxis (56%), PE with a contraindication to anticoagulation therapy (27%), and complication (7%) or failure (9%) of anticoagulation therapy. Early mortality in the surgical and percutaneous groups was 26% and 27%, respectively. Ten percent of early deaths in the surgical group and 50% in the percutaneous group were associated with prophylactic insertions (P = 0.032). Associated morbidity was 8% in the surgical versus 24% in the percutaneous group (P = 0.036). The unrestricted use of prophylactic percutaneous IVC filters appears to have resulted in an increased procedure-related morbidity with no clear benefit in early patient survival. These findings suggest a need for improved patient selection.

Outcome of complex vascular and orthopedic injuries of the lower extremity.

Thirty-two patients undergoing limb salvage procedures for complex vascular and orthopedic injuries of the lower extremity were studied in order to identify prognostic indicators for delayed amputation in this select group. A high incidence of nerve (38%), soft tissue (66%), and remote injury (47%) was noted. A comprehensive and integrated approach to vascular, orthopedic, and plastic reconstruction was utilized. Of the 32 patients studied, 1 (3.1%) died as a result of remote injury and sepsis. Amputation was required in 9 patients (28%), while 13 (56%) of the patients with limb salvage showed persistent functional or neurologic deficits. Infection was the most significant factor associated with amputation (p less than 0.0005) and was not avoided by the perioperative use of antibiotics. Delayed amputation resulted in a significant extension of total hospitalization (p less than 0.005). The authors favor an aggressive approach to limb salvage with IIIC injury but recommend early amputation in the presence of significant nerve disruption. An attentive use of tissue debridement, intravenous antibiotics, and early wound coverage is needed to limit infection.

The role of composite sequential bypass in the treatment of multilevel infrainguinal arterial occlusive disease.

BACKGROUND: In this study, the efficacy of composite sequential bypass is compared to that of standard in situ bypass, and to alternate prosthetic graft systems which have been used for the treatment of multilevel infrainguinal arterial occlusive disease in the absence of suitable autogenous vein. PATIENTS AND METHODS: A retrospective review of graft patency and limb salvage included 197 patients undergoing 211 bypass procedures consisting of in situ femoral-tibial (IS; n = 119); composite sequential (CS; n = 35), prosthetic femoropopliteal with single (PFP-1; n = 30) or no vessel runoff (PFP-O; n = 9), and prosthetic femoral-tibial (PFT; n = 18) bypass. RESULTS: By life-table analysis, IS bypass provided superior primary (P < 0.005) and secondary (P < 0.0005) patency over the other groups. CS bypass was similar to PFP-1, with a 2-two year primary patency of 35% and 44% (NS), respectively, and limb salvage rates of 60% and 80% (P = 0.01). PFP-O and PFT bypass procedures did considerably worse, with a 1-year patency of 19% and 22%, respectively, and associated limb salvage rates of 25% and 41% (NS). CONCLUSIONS: Composite sequential bypass is an acceptable procedure for infrainguinal arterial reconstruction when absence of autogenous vein prevents either in situ or secondary vein graft bypass procedures.

Value of radiographs and bone scans in determining the need for therapy in diabetic patients with foot ulcers.

Thirty-two diabetic patients with foot ulcers were evaluated. Twenty-five patients had foot radiographs, technetium-99m bone scans, and wound and bone cultures; the remaining seven patients had all the studies except bone scanning. Bone changes compatible with osteitis were present on 15 of 32 foot radiographs (47 percent) and on 16 of 25 bone scans (64 percent). Bacterial growth was present in 27 of 32 wounds (84 percent) and 23 of 32 bone cultures (72 percent). Twelve of 23 patients (52 percent) with positive bone cultures had evidence of bone destruction and periosteal reaction on radiographs. The remaining 11 of 23 patients (48 percent) without radiographic signs of osteitis had bacterial growth from their bone cultures. Bone scans were positive in 12 of 18 patients (67 percent) with positive bone cultures and negative in 6 of 18 positive bone cultures (33 percent). We conclude that neither foot radiographs, technetium-99m bone scans, nor wound cultures should be used as the sole criterion for determining the use of antibiotic therapy or amputation in diabetic patients with foot ulcers.

Is deep vein thrombosis surveillance warranted in high-risk trauma patients?

BACKGROUND: Deep vein thrombosis (DVT) has been reported to occur in 20% to 40% of high-risk trauma patients if no prophylaxis is used. The purpose of this study was to determine the incidence of DVT and utility of a screening program in a high-risk group of trauma patients for whom routine DVT prophylaxis was utilized. PATIENTS AND METHODS: Of 3,154 trauma admissions over a 20-month period, 343 patients (10.9%) identified as high risk based on established criteria (prolonged bed rest, Glasgow coma score (GCS) of 7, spinal injury, lower extremity or pelvic fracture) were placed on a prospective surveillance protocol using color-flow duplex scanning and received thromboembolic prophylaxis. RESULTS: Twenty-three thromboembolic complications occurred, including 20 DVTs (5.8%) and 3 pulmonary emboli ([PE] 1%). Univariate analysis showed that the risk of DVT was related to age (52.6 + 19.9 years versus 38.1 + 18.5; P = 0.001), a longer hospital stay (31.4 versus 17.8 days; P = 0.001), or the presence of spinal fracture (12.6% versus 3.5%; P = 0.01). Discriminant function analysis revealed that length of stay, intensive care unit days, age, and GCS allowed correct classification of those who did not develop DVT in 97% of cases but was only correct in 15% of cases in predicting those who would develop DVT. Injury severity score (ISS) was not predictive in this multivariate analysis. Seventeen (85%) DVTs were unsuspected clinically. Study patients received an average of 3.5 studies at an overall charge of $313,330 to detect 17 clinically unsuspected DVTs (5%). This represents about 5% of the total bed charges for these patients, or $18,000 per DVT. CONCLUSIONS: These results suggest that standard use of DVT prophylaxis in a high-risk trauma population leads to a low incidence of DVT and that a screening protocol is effective in detecting unsuspected DVTs. Use of a surveillance protocol, however, may reduce but will not eliminate the incidence of pulmonary emboli in this patient population.

Selection of grafts currently available for repair of abdominal aortic aneurysms.

The ideal vascular graft has not yet been developed. However, in the aortic position, excellent results can be obtained using a variety of currently available grafts, which offer similar patency rates and durability. Therefore, graft selection depends on other considerations, such as the ease of handling and preclotting requirements.

Thyroidectomy in patients with marked thyroid enlargement: airway management, morbidity, and outcome.

The medical records of 91 patients who underwent thyroidectomy from 1990 to 1993 were reviewed to evaluate airway management and operative morbidity in patients with marked thyroid enlargement. Twenty-nine patients with marked thyroid enlargement were identified: 13 unilateral, defined by a weight of > or = 40 g (mean 122 g, range 41-380 g), and 16 bilateral, defined by a weight of > or = 80 g (mean 160 g, range 82-404 g). Twenty-five patients had compressive symptomatology, 18 had tracheal narrowing and/or displacement, 19 had substernal extension, and one had superior vena cava syndrome. Unilateral vocal cord dysfunction was present in two of three patients with carcinoma and one of 26 patients with benign disease (P = 0.03). Pathology consisted of nodular goiter (11), adenoma (5), carcinoma (3), Grave's disease (5), and toxic multinodular goiter (5). All patients had an uncomplicated endotracheal intubation without the use of a fiberoptic bronchoscope as predicted on the basis of preoperative laryngoscopic findings. Ease of intubation was unrelated to the extent of abnormality seen on imaging studies of the neck. Thyroidectomy alone was effective in relieving compressive symptoms with no incidence of nerve injury, permanent hypoparathyroidism, or tracheomalacia. Six (21%) of 29 patients had temporary hypocalcemia compared to eight (13%) of 62 patients with lesser thyroid enlargement (P = 0.36). One patient with an unresectable follicular carcinoma died from aspiration pneumonia three weeks following tracheostomy placement. Marked thyroid enlargement and upper airway compression is predominantly caused by benign disease; however, when there is associated recurrent laryngeal nerve dysfunction, carcinoma is more common.(ABSTRACT TRUNCATED AT 250 WORDS)

Idiopathic necrotizing fasciitis: recognition, incidence, and outcome of therapy.

Early recognition and treatment of necrotizing fasciitis (NF) is essential for survival. The diagnosis of primary or idiopathic NF may be particularly challenging because it occurs in the absence of a known causative factor or portal of entry for bacteria. Patients with NF treated between 1989 and 1993 were reviewed to determine the incidence, clinical features, bacteriology, and results of treatment in patients with idiopathic NF. Idiopathic NF occurred in nine (18%) of 51 patients, five men and four women, ranging in age from 21 to 67 years. Associated conditions included diabetes mellitus (4), alcoholism (3), remote infection (3), and pregnancy (2). NF affected the lower extremity in eight and the perineum in one patient. Pain and tenderness occurred in all patients, soft tissue gas was recognized in two, and the presence of erythema and edema was variable. Idiopathic NF was monomicrobial in seven (78%) patients, compared to 21 per cent of patients with secondary NF (P = 0.003). S. pyogenes was the causative organism in five of seven monomicrobial infections. Time from admission to operation was significantly longer (62.3 +/- 54.8 hours) in patients with idiopathic NF compared to patients with secondary NF (17.0 +/- 16.6 hours) (P = 0.001). Treatment included operative debridement (means = 3.3) and limb amputation (n = 1) to control infection. Three patients (33%) with idiopathic NF died. Primary or idiopathic NF is principally a monomicrobial infection usually caused by S. pyogenes that most commonly occurs in the extremities. Mortality is high but is comparable to secondary NF. It is important to recognize that NF may occur spontaneously, and it should be suspected in patients with unexplained soft tissue pain and tenderness.

Transcranial gunshot wounds: cost and consequences.

Poor outcomes following transcranial gunshot wounds (TC-GSW) and the perception of significant financial loss have led some institutions to adopt a fatalistic attitude towards these patients. This study was undertaken to define those factors predictive of mortality following TC-GSW as well as to determine the costs and benefits associated with providing care to these individuals. We reviewed the medical records of 57 TC-GSW patients seen at our Level I Trauma Center between January 1990 and December 1992. Overall mortality was 75 percent, and was statistically associated with an admission Glasgow Coma Score of 4 or less, a respiratory rate of less than 10, and self-inflicted wounds. Complete financial information was available for 37 of the 57 patients. Reimbursements for this group were $306,156 and exceeded costs by $62,257. Organ donation efforts were successful in 44.2 per cent of the nonsurvivors (19/43), yielding 60 organs and 29 tissues for transplantation. Nonsurvivors who became organ donors were clinically and demographically indistinguishable from those in whom organs/tissues could not be retrieved. Despite the poor outcome following TC-GSW, vigorous resuscitation and stabilization is justified in all patients, in that nearly one half of nonsurvivors will become organ and/or tissue donors. Concerns regarding excessive monetary looses by treating facilities are unfounded.

Rupture of known abdominal aortic aneurysms: an ethical dilemma.

Elderly patients with abdominal aortic aneurysms (AAA) may be deemed inoperable due to the presence of comorbid conditions. Presentation of these patients with acute rupture can then result in difficult ethical decisions regarding surgical treatment. Over six years, 80 patients were treated emergently for ruptured AAA. Of these patients, 26 (32.5%) had known aneurysms. This study was performed to determine outcome and factors affecting mortality in patients with known AAAs. There were no significant differences between known and unknown AAA groups with regard to operative risk. In the overall group (n = 80), patient delay in seeking treatment averaged 20.4 hours with a trend towards shorter times in those with known AAAs (13.8 hours) compared with the unknown group (23.6 hours; p = 0.09). Medical transport delay, however, was significantly shorter for patients with known AAA (124 minutes versus 230 minutes; p = 0.04). Overall mortality was 56 per cent (n = 45). Those patients with known AAAs had a higher mortality (69%; n = 18) than those with unknown AAAs (50%, n = 27) but this was not statistically significant (P = 0.10). In patients with known AAAs, operative death was related to patient delay, with an average delay in seeking medical advice of 21.3 hours in nonsurvivors compared with 8.6 hours in survivors (P = 0.04). No other risk or demographic factors correlated with mortality. Despite a known AAA, significant delay in seeking medical advice occurred, and this delay resulted in decreased survival. Patient education is imperative if nonoperative treatment is chosen.(ABSTRACT TRUNCATED AT 250 WORDS)

Colonic ischemia: the Achilles heel of ruptured aortic aneurysm repair.

Colonic ischemia is an often fatal complication of abdominal aortic aneurysm (AAA) repair. In elective AAA repair, patency of the inferior mesenteric artery (IMA) has been shown to be an important contributing factor. The purpose of this study was to determine which clinical and operative factors are important in the development of colonic ischemia in ruptured AAA repair. A retrospective review of all patients treated for ruptured AAA over a 7-year period was performed. Of 101 patients who were treated for ruptured AAA, 71 (70 per cent) survived for longer than 24 hours postoperatively, and these patients are the basis for this study. Colonic ischemia, primarily left sided, was a common perioperative complication (n = 24; 35 per cent) requiring colectomy in 11 patients (44 per cent). It carried a 44 per cent mortality compared to 20 per cent in patients without this complication (P = 0.07). Colonic ischemia occurred more frequently in patients with preoperative shock (P = 0.01) and a greater intraoperative blood loss (P = 0.003), but showed no correlation with patient age, co-morbid medical conditions, laboratory values, time to operation, or treatment of the IMA. Most patients with postoperative bowel ischemia were found to have chronic IMA occlusion, including 8 of the 11 patients requiring colectomy. Revascularization would not be feasible in this group. Revascularization of patent IMAs had little effect on outcome. Of the 17 patent IMAs, 9 were reimplanted and 5 (55 per cent) developed bowel ischemia, two of which required colectomy. Eight were ligated and 3 (38 per cent) developed bowel ischemia, one requiring colectomy. The presence of preoperative shock is the most important factor predicting the development of colonic ischemia following ruptured AAA. The incidence of ischemia is not altered by the presence of a patent IMA or with attempts at IMA revascularization. Colonic ischemia remains a significant source of morbidity and mortality in these patients.

Effect of chronic consumption of ethanol and vitamin E on fatty acid composition and lipid peroxidation in rat heart tissue.

Lipid peroxidation products and the fatty acid composition of phospholipids were studied in the hearts of rats chronically consuming ethanol supplemented with large amounts of vitamin E. Ethanol representing 36% of the total calories was ingested for 7 weeks in a modified Lieber-DeCarli liquid diet that contained vitamin E at 30 IU/L in the control or 172 IU/L in the supplemental dietary group. Ethanol and/or vitamin E did not change the absolute content (micrograms per mg of phospholipids) of the main fatty acids (C18:0, C18:2, and C20:4) of heart phospholipids but increased the amount of the minor C20-C22 fatty acids. Cardiac phospholipid levels increased in rats chronically consuming excess vitamin E and/or alcohol. Chronic ethanol consumption caused elevations of the relative content (percent of total fatty acids) of tri-, tetra-, and hexaenoic acids and peroxidizability index (PI) of the cardiac phospholipids. Supplementation with vitamin E blocked this ethanol-induced shift in the fatty acid profile toward unsaturation and decreased the PI. Ethanol enhanced accumulation of vitamin E in heart tissue by 30% irrespective of the vitamin E content in the diet. Enrichment of the diet with vitamin E coincided with the low levels of fluorescent products in heart lipids. A positive correlation (r = 0.36; p = 2%) was found between vitamin E and diene conjugates in the heart cells. Thus, vitamin E has a stabilizing effect on heart phospholipids by preventing changes in their fatty acid composition and peroxidative deterioration.

Outcome of intraarterial urokinase for acute vascular occlusion.

Intraarterial urokinase (IAUK) was administered to 33 patients on 40 occasions for the treatment of acute extremity ischemia and long-term patency was assessed. Lysis was successful in 39 of the 40 cases (95%). Occlusive thrombus was cleared in 12 of 13 patients with native artery occlusion (7 complete, 5 partial), 8 of 9 with autologous vein grafts (5 complete, 3 partial), and in all 18 patients with synthetic grafts (17 complete, 1 partial). The primary cumulative patency following successful IAUK was 100% for native arteries and 47% for synthetic grafts at 12 months, and 23% for autologous grafts at 9 months. The difference in rethrombosis rate between autologous vein (67%) and native artery (0%) was significant (p = 0.02) as was the difference between infrainguinal prosthetic grafts (63%) and native artery (p = 0.025). IAUK is most effective for the treatment of native artery occlusion, but is significantly less effective for thrombosed infrainguinal autologous vein or synthetic grafts due to the likelihood of reocclusion, despite the high immediate success rate. For autologous vein grafts, lysis is frequently incomplete and patency rapidly deteriorates regardless of adjunctive therapy to relieve the underlying obstruction.

Emergency department tracheostomy.

Emergency Department tracheostomy is performed in the rare instances of extensive laryngeal trauma in the adult and emergent airway access in the infant. This article reviews indications, anatomy, technique, and complications of this challenging life-saving procedure.

The preventative effect of pyridine on stress ulcers: a microvascular and morphological study.

The effect of pyridine in the prevention of cold restraint-induced stress ulcers in rats was investigated. After fasting, rats were administered the appropriate dosage of pyridine and were promptly placed into stress cages for cold room stress. The rats were sacrificed and bleeding, ulceration and vascular patency were examined. At doses of 0.01 mg/kg and 0.20 mg/kg, pyridine significantly decreased the amount of gastric hemorrhage and ulceration (p less than 0.01), as compared with the controls. In addition, microvascular dye, injected after stress, revealed perfused mucosal capillaries in the pyridine group, and occlusion of mucosal capillaries in the control group. These results suggest that the antiplatelet effect of pyridine reduced thrombus formation in the mucosal capillaries with subsequent reduction in mucosal ulceration.