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Internal hernias are the causes of 0.5 to 5.8 per cent of all cases of small bowel obstruction. Left paraduodenal hernia (PDH) is the most common congenital internal hernia encountered in adults. The symptoms and physical findings associated with PDH are vague and nonspecific before the onset of complicated intestinal obstruction. Diagnoses are most commonly established by CT. This case presentation and review is intended to promote clinicians’ awareness of this unusual but potentially highly morbid condition, discuss CT findings associated with PDH, and illustrate the importance of timing in the acquisition of diagnostic abdominal CT scans.

Pan computed tomography (PCT) of the head, cervical spine, chest, abdomen, and pelvis is a valuable approach for rapid evaluation of severely injured blunt trauma patients. A PCT strategy has also been applied for the evaluation of patients with lower injury severity; however, the cost-utility of this approach is undetermined. The advantage of rapidly identifying all injuries via PCT must be weighed against the risk of radiation-induced cancer (RIC). Our objective was to compare the cost-utility of PCT with selective computed tomography (SCT) in the management of blunt trauma patients with low injury severity.A Markov model-based, cost-utility analysis of a hypothetical cohort of hemodynamically stable, 30-year-old males evaluated in a trauma center after motor vehicle crash was used. CT scans are performed based on the mechanism of injury. The analysis compared PCT with SCT over a 1-year time frame with an analytic horizon over the lifespan of the patients. The possible outcomes, utilities of health states, and health care costs including RIC were derived from the published medical literature and public data. Costs were measured in US 2010 dollars, and incremental effectiveness was measured in quality-adjusted life-years (QALYs) with 3% annual discounted rates. Multiway sensitivity analyses were performed on all variables.The total cost for blunt trauma patients undergoing PCT was $15,682 versus $17,673 for SCT. There was no difference in QALYs between the two populations (26.42 vs. 26.40). However, there was a cost savings of $75 per QALY for patients receiving PCT versus SCT ($594 per QALY vs. $669 per QALY).PCT enables surgeons to identify and rule out injuries promptly, thereby reducing the need for inpatient observation. The risk of RIC is low following a single PCT. This cost-utility analysis finds PCT based on mechanism to be a cost-effective use of resources.Economic and value-based evaluations, level II.

Trauma patients receive emergency transfusions of unmatched Type O Rh-negative (Rh-) blood until matched blood is available. We hypothesized that patients given uncrossmatched blood may develop alloantibodies, placing them at risk for hemolytic transfusion reactions (HTRs).Data regarding alloantibody profiles and HTR occurrence were collected from the records of trauma patients at our university-based trauma center who received emergency uncrossmatched blood from July 2008 to August 2010.A total of 132 patients received 1,570 units of packed red blood cells. Mean injury severity score was 28 ± 1.3. Forty-five (34%) patients died: 27 on hospital day 1; the remaining 18 had no evidence of HTR before death. Four Rh- female patients received Rh+ fresh frozen plasma, but none received Rh+ packed red blood cells. Three Rh- male patients received both Rh+ packed red blood cells and fresh frozen plasma, and one received Rh+ fresh frozen plasma. One patient developed anti-Rh D antibodies. None experienced HTR. One female patient had HTR from reactivation of anamnestic JK antibodies. Thirteen (33%) of 39 patients met criteria for HTR based on urinalysis and 29 (40%) of 72 patients tested met criteria for HTR based on hemoglobin and bilirubin values. Only one patient had confirmed HTR.High rates of injury recidivism in trauma patients increase the likelihood of multiple blood transfusions during their lifetime. Rh- patients who receive Rh+ blood are at risk of developing anti-Rh antibodies, putting them at risk for HTR. The conservation of Rh- blood for use in female patients may be detrimental to Rh- male patients. Laboratory diagnostic criteria for HTR are nonspecific in the trauma population and should be used with caution.

Background We have used single-contrast (intravenous contrast only) computed tomography (SCCT) for triaging hemodynamically stable patients with penetrating torso trauma. We hypothesized that SCCT safely determines the need for operative exploration. Furthermore, trauma surgeons without specialized training in body imaging can accurately apply this modality. Methods We retrospectively reviewed the records of patients with penetrating torso injuries at a university-based urban trauma center to establish the accuracy of SCCT in determining the need for exploratory laparotomy. The scan was considered positive or negative with respect to the need for exploratory laparotomy as documented by the attending surgeon, who may have considered the read of the on call radiologist if available. In a separate study, four trauma surgeons independently reviewed 42 SCCT scans to establish whether the scans alone could be used to determine whether operative exploration was necessary. Results Between 1997 and 2008, 306 hemodynamically stable patients with penetrating torso trauma were triaged by SCCT. Overall, SCCT predicted the need for laparotomy with 98% sensitivity and 90% specificity. The positive predictive value was 84% and the negative predictive value (NPV) was 99%. In the 222 patients with gunshot wounds, SCCT had 100% sensitivity and 100% NPV. In the 84 patients with stab wounds, SCCT had 92% sensitivity and 97% NPV. Trauma surgeon agreement in the retrospective review of 42 computed tomography scans was "nearly perfect": positive predictive value was 93% and NPV was 92% for determining the need for exploratory laparotomy surgery. Conclusions SCCT is safe and effective for triaging hemodynamically stable patients with penetrating torso trauma. It successfully determined the need for operative intervention with appropriate clinical accuracy without the additional costs, morbidity, and delay of oral and rectal contrast. Trauma surgeons can reproducibly interpret SCCT with high-predictive accuracy as to whether patients with penetrating torso trauma require operative exploration.

We hypothesized that surgical resident stress involves both psychologic and physiologic components that manifest as changes in heart rate (HR) and circulating white blood cell (WBC) count. The purposes of this series of experiments were to monitor HR as a measure of stress "on call"; to monitor WBC count (1,000 cells/microL) during "on call" periods as a measure of stress; and to relate maximum HR and WBC count "on call" to surgical resident training level.HR was continuously documented by Holter monitor for 24hours "on call" in interns (n = 6), junior residents (n = 5), and senior residents (n = 5). Interns (n = 4), junior residents (n = 4), and senior residents (n = 4) during periods devoid of clinical responsibilities served as controls. WBC counts were obtained from residents "off" and "on call" for interns (n = 5) and junior residents (n = 5).Mean HR "on call" increased in all resident groups as compared with controls: intern mean HR increased from 71 +/- 3 to 87 +/- 2 beats per minute (bpm) (p = 0.003), junior resident mean HR increased from 74 +/- 3 to 88 +/- 4 bpm (p = 0.03), and senior resident mean HR increased from 69 +/- 2 to 80 +/- 2 bpm (p = 0.004). Intern maximum control HR was 119 +/- 3 and increased to 149 +/- 6 bpm (p = 0.005). The increase in maximum HR (control versus "on call") did not reach significance in junior residents (123 +/- 5 to 136 +/- 6 bpm, p = 0.14) and senior residents (115 +/- 6 to 116 +/- 3 bpm, p = 0.9). WBC count in interns increased from control values of 5.2 +/- 0.6 x 1,000 cells/microL to 7.5 +/- 0.9 x 1,000 cells/microL"on call" (p = 0.005). The WBC change in juniors was not significant (control: 6.8 +/- 0.7 x 1,000 cells/microL, "on call": 7.1 +/- 0.7 x 1,000 cells/microL; p = 0.37).When heart rate is used as an indicator of combined physiologic and psychologic stress, surgical residents achieve stress levels of tachycardia "on call." Surgical residents also exhibit an increase in circulating WBC count "on call." Both the degree of tachycardia and the increase in WBC count are inversely related to the level of training. Senior residents cope better with stress "on call" than junior residents and interns.

Purpose: The surgical resident experience with trauma has changed. Many residents are exposed to predominantly nonoperative patient care experiences while on trauma rotations. Data from a large multicenter study were analyzed to estimate surgical resident exposure to trauma laparotomy, diagnostic peritoneal lavage (DPL), and focused abdominal sonography for trauma (U/S). Methods: Centers completed a self-report questionnaire on their institutional demographics, admissions, and procedure for a 2-year period (1998-1999). Results: A total of 82 trauma centers that provide resident teaching were included. The included centers represent over 247,000 trauma admissions. The majority of trauma centers (65.9%) had > 80% blunt injury. Although all centers performed laparotomies, other results were more variable. For U/S, 24.2% performed none at all and 47.0% performed fewer than two U/S examinations per month. For DPLs, 3.8% performed none and 66.7% performed fewer than two per month. Assuming 1 night of 4 on call, the average surgical resident training at a trauma center performing > 80% blunt trauma has the potential to participate in only 15 trauma laparotomies, 6 diagnostic peritoneal lavages, and 45 ultrasound examinations per year. In addition, the resident will care for an average of 500 blunt trauma patients before performing a splenectomy or liver repair. Conclusion: Surgical resident experience on most trauma services is heavily weighted to nonoperative management, with a relatively low number of procedures, little experience with DPL, and highly variable experience with ultrasound. These data have serious implications for resident training and recruitment into the specialty.

Lipopolysaccharide (LPS) and gut ischemia/reperfusion (I/R) injury cause reversible liver injury. Because nitric oxide (NO) can have both beneficial and deleterious effects in the gastrointestinal tract, and because the role of NO in gut I/R-induced hepatic injury is unknown, this study examined its role in LPS and gut I/R-induced hepatic injury in the rat. Both LPS and gut I/R caused a similar increase in serum hepatocellular enzymes. LPS but not gut I/R caused a significant increase in upregulation of hepatic inducible NO synthase (iNOS) according to quantitative real-time RT-PCR and Western immunoblot analysis. Aminoguanidine, a selective iNOS inhibitor, attenuated LPS-induced hepatic injury and hypotension, but did not prevent gut I/R-induced hepatic injury. In contrast, the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester aggravated liver damage from both LPS and gut I/R. These data indicate that iNOS plays a role in mediating LPS-induced hepatic injury, but not gut I/R-induced hepatic injury. The data also suggest that the constitutive isoforms of NOS play a hepatoprotective role in both models of hepatic injury.

Background: Surgical wound infection and intra-abdominal abscess remain common infectious complications after appendectomy, especially in the setting of a perforated or gangrenous appendix. We therefore developed a clinical protocol for the management of appendicitis to decrease postoperative infectious complications. Methods: Between January 1, 1999, and December 31, 1999, 206 patients with appendicitis were treated on protocol. Retrospectively, the charts were reviewed for all protocol patients as well as for 232 patients with appendicitis treated in the year prior to protocol initiation. Data were collected on surgical wound infections and intra-abdominal abscesses. Results: There were significantly fewer infectious complications in the protocol group than in the nonprotocol group (20 [9%] versus 8 [4%]; P

Laparoscopic cholecystectomy (LC) is the preferred method of treatment for patients with gallbladder disease in the elective setting. Despite being technically more difficult, LC performed during the early course of acute cholecystitis can be safe and cost-effective. The current review discusses the diagnostic and therapeutic strategies that may help promote the safe and successful laparoscopic treatment of patients with acute cholecystitis. Copyright 2002, Elsevier Science (USA). All rights reserved.

Background Hospital-centered violence intervention programs (HVIPs) reduce violent injury recidivism. However, dedicated cost analyses of such programs have not yet been published. We hypothesized that the HVIP at our urban trauma center is a cost-effective means for reducing violent injury recidivism. Methods We conducted a cost-utility analysis using a state-transition (Markov) decision model, comparing participation in our HVIP with standard risk reduction for patients injured because of firearm violence. Model inputs were derived from our trauma registry and published literature. Results The 1-year recidivism rate for participants in our HVIP was 2.5%, compared with 4% for those receiving standard risk reduction resources. Total per-person costs of each violence prevention arm were similar: $3,574 for our HVIP and $3,515 for standard referrals. The incremental cost effectiveness ratio for our HVIP was $2,941. Conclusion Our HVIP is a cost-effective means of preventing recurrent episodes of violent injury in patients hurt by firearms.

SummaryBackground The role of routine prophylactic central neck dissection (CND) in papillary thyroid cancer (PTC) remains controversial. The aim of this study was to evaluate the cost utility of the addition of routine CND in patients with low-risk PTC compared with total thyroidectomy (TT) alone. Methods A Markov model for low-risk PTC was constructed with a treatment algorithm based on the American Thyroid Association guidelines for well-differentiated thyroid carcinoma. Utilities and outcome probabilities were derived from published medical literature. US 2010 costs were examined from a society perspective using Medicare reimbursement rates and opportunity loss based on published US government data. Monte Carlo simulation and sensitivity analysis were used to examine the uncertainty of probability, cost and utility estimates. Results Initial TT alone is more cost-effective than TT with CND, resulting in a cost savings of US $5763 per patient with slightly higher effectiveness per patient (0·03 QALY) for a cost savings of $285 per QALY. Sensitivity analysis shows that TT alone offers no advantage when radioactive iodine (RAI) becomes more detrimental to a patient's state of health, when the incidence of non-neck recurrence increases above 5% in patients undergoing TT alone or decreases below 3·9% in patients undergoing TT with CND or when the rate of permanent hypocalcaemia rises above 4%. Conclusions TT with CND is not a cost-effective strategy in low-risk PTC. Initial TT alone is favourable because of the low complication rates and low recurrence rates associated with the initial surgery. Alternative strategies such as unilateral prophylactic neck dissection require additional study to assess their cost-effectiveness.

Background Papillary thyroid carcinoma (PTC) with BRAF mutation carries a poorer prognosis. Prophylactic central neck dissection (CND) reduces locoregional recurrences, and we hypothesize that initial total thyroidectomy (TT) with CND in patients with BRAF-mutated PTC is cost effective. Methods This cost-utility analysis is based on a hypothetical cohort of 40-year-old women with small PTC [2 cm, confined to the thyroid, node(−)]. We compared preoperative BRAF testing and TT+CND if BRAF-mutated or TT alone if BRAF-wild type, versus no testing with TT. This analysis took into account treatment costs and opportunity losses. Key variables were subjected to sensitivity analysis. Results Both approaches produced comparable outcomes, with costs of not testing being lower (−$801.51/patient). Preoperative BRAF testing carried an excess expense of $33.96 per quality-adjusted life-year per patient. Sensitivity analyses revealed that when BRAF positivity in the testing population decreases to 30%, or if the overall noncervical recurrence in the population increases above 11.9%, preoperative BRAF testing becomes the more cost-effective strategy. Conclusion Outcomes with or without preoperative BRAF testing are comparable, with no testing being the slightly more cost-effective strategy. Although preoperative BRAF testing helps to identify patients with higher recurrence rates, implementing a more aggressive initial operation does not seem to offer a cost advantage.

The American College of Surgeons' Committee on Trauma's recent prehospital trauma life support recommendations against prehospital spine immobilization (PHSI) after penetrating trauma are based on a low incidence of unstable spine injuries after penetrating injuries. However, given the chronic and costly nature of devastating spine injuries, the cost-utility of PHSI is unclear. Our hypothesis was that the cost-utility of PHSI in penetrating trauma precludes routine use of this prevention strategy.A Markov model based cost-utility analysis was performed from a society perspective of a hypothetical cohort of 20-year-old males presenting with penetrating trauma and transported to a US hospital. The analysis compared PHSI with observation alone. The probabilities of spine injuries, costs (US 2010 dollars), and utility of the two groups were derived from published studies and public data. Incremental effectiveness was measured in quality-adjusted life-years. Subset analyses of isolated head and neck injuries as well as sensitivity analyses were performed to assess the strength of the recommendations.Only 0.2% of penetrating trauma produced unstable spine injury, and only 7.4% of the patients with unstable spine injury who underwent spine stabilization had neurologic improvement. The total lifetime per-patient cost was $930,446 for the PHSI group versus $929,883 for the nonimmobilization group, with no difference in overall quality-adjusted life-years. Subset analysis demonstrated that PHSI for patients with isolated head or neck injuries provided equivocal benefit over nonimmobilization.PHSI was not cost-effective for patients with torso or extremity penetrating trauma. Despite increased incidence of unstable spine injures produced by penetrating head or neck injuries, the cost-benefit of PHSI in these patients is equivocal, and further studies may be needed before omitting PHSI in patients with penetrating head and neck injuries.Economic and value-based evaluation, level II.

Gallstone disease poses a major health problem in the United States. More than 600,000 cholecystectomies are performed yearly, with estimated direct costs for the diagnosis and treatment of gallstones exceeding $5 billion annually. 1 Choledocholithiasis is detected in 8% to 20% of patients undergoing cholecystectomy. 2–4 Several options are available for the diagnosis and treatment of choledocholithiasis, but there is no consensus on the optimal management strategy for these patients. 5 The selection of diagnostic and treatment approaches depends on multiple factors, including the level of suspicion for choledocholithiasis, patient and physician preferences, resource availability, and the expertise of the surgeons, endoscopists, and radiologists. Clinical, ultrasonographic, and serum chemistry data commonly acquired during patient evaluations are sensitive in 96% to 98% and specific in 40% to 75% of the patients for the determination of choledocholithiasis. 2–4 Therefore, when these indicators are used for the selection of patients for endoscopic retrograde cholangiopancreatography (ERCP), up to 75% of the patients have no common bile duct (CBD) stones found during the procedure. Even though ERCP is effective for the diagnosis and clearance of CBD stones, this procedure can be associated with patient discomfort, inconvenience, and complications. 6 Magnetic resonance cholangiography (MRC) has been shown to possess diagnostic accuracy comparable to that of ERCP. 7–12 In a previous study, we selected patients for MRC imaging on the basis of clinical evaluation, serum liver enzyme elevations, and CBD dilatation as detected by abdominal ultrasonography 11 (Fig. 1 contains our previous management algorithm). Whereas MRC application resulted in accurate diagnosis of choledocholithiasis, we believed the approach was associated with overuse. Subsequently, we modified the approach to the management of patients with gallstone disease at our institution. The management approach categorized patients into four groups based on the level of suspicion for choledocholithiasis, which then directed patient evaluation and management. We hypothesized that with the implementation of these triage guidelines, there would be a reduction in redundant and unnecessary diagnostic testing, thus leading to improvements in magnetic resonance imaging and ERCP utilization. The utility of the new management guidelines was evaluated in this prospective nonrandomized study involving 440 patients. Figure 1. Previous patient management algorithm: AST, aspartate transaminase; ALT, alanine transaminase; MRC, magnetic resonance cholangiography; ERCP, endoscopic retrograde cholangiopan-creatography.

Common bile duct stones are generally classified as primary or secondary stones based on the locations of origin. The vast majority of the stones found in the biliary tree are secondary stones. The current review discusses the pathogenesis and presentations of primary and secondary biliary stones. Based on discussion of disease pathogenesis and presentation, recommendations for the evaluation and management of common and uncommon disease processes associated with choledocholithiasis are proposed.

Inflammatory pseudotumor (IPT) of the pancreas occurs rarely. Eighteen cases have been described in the English literature. In all previous patients IPT of the pancreas presented as solid pancreatic mass. We are reporting a case of IPT presenting as a cystic mass of the pancreas, which has not been described previously. A review of IPT of the pancreas and a discussion regarding the management of pancreatic cystic neoplasm is provided.

Background: Endoscopic retrograde cholangiography is the most commonly utilized tool for the identification of common bile duct stones (CBDS) before laparoscopic cholecystectomy, whereas the role of magnetic resonance cholangiography (MRC) for patient evaluation before laparoscopic cholecystectomy is currently undefined. Methods: We prospectively evaluated the efficacy of MRC for the identification of CBDS among patients with high risk for choledocholithiasis. Patient selection was based on clinical, sonographic, and laboratory criteria. Standard cholangiograms were obtained when possible for verification of MRC results. Results: Ninety-nine patients underwent evaluation with preoperative MRC. CBDS was visualized in 30% of patients. MRC sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 85%, 90%, 77%, 94%, and 89%, respectively. Conclusions: MRC is useful for the evaluation of patients with suspected choledocholithiasis. Advantages of MRC include its noninvasive nature, ease of application, and accuracy in identifying and estimating the size of CBDS. Application of MRC in this setting reduces the need for diagnostic endoscopic retrograde cholangiography. Future investigations should be directed at the development of cost-effective utilization strategies for MRC application.

Laparoscopic cholecystectomy (LC) is the preferred method of treatment for patients with gallbladder disease in the elective setting. Despite being technically more difficult, LC performed during the early course of acute cholecystitis can be safe and cost-effective. The current review discusses the diagnostic and therapeutic strategies that may help promote the safe and successful laparoscopic treatment of patients with acute cholecystitis.

Introduction. Surgical resident stress includes psychological and physiological components which relate linearly to heart rate (HR), oxygen consumption (VO 2 ), and neutrophil demargination. The purposes of this series of experiments were (1) To relate HR to VO 2 in surgical residents during exercise; (2) to monitor HR as a measure of stress on call; (3) to relate maximum HR on call by surgical resident training level; and (4) to monitor white blood cell (WBC) count as a measure of stress during call. Methods. HR and VO 2 were monitored in surgeons ( n = 5) during bicycle ergometry. HR was continuously monitored (Holter) for 24 h on call for interns ( n = 6), and junior ( n = 5) and chief residents ( n = 5). WBC counts were obtained from residents off and on call ( n = 6). Results. HR (72 ± 5 to 124 ± 4 BPM) correlates with VO 2 (273 ± 24 to 1535 ± 103 mlO 2 /min) R 2 = 0.843. Control maximal HR was 110 ± 3. Compared to controls, on call maximal HR was elevated for interns and junior residents to 149 ± 6 ( P = 0.0003) and 136 ± 6 ( P = 0.009), respectively, but was unchanged in chief residents at 116 ± 3 ( P = 0.5). There were no 1-h time periods during which the HR was above 120 bpm in controls. This number of 1-h time periods increased to 7 ± 1 in the interns ( P = 0.01) and 6 ± 3 in the junior residents ( P = 0.03), but was unchanged in senior residents, 0.4 ± 0.2 ( P = 0.8). WBC increased from 5.7 ± 0.4 to on call values of 7.2 ± 0.6 (p = 0.04). Neutrophils decreased from 58 to 49% ( P = 0.005). This was offset by an increase in lymphocytes from 33 to 40% ( P = 0.009). Conclusion. We conclude that HR correlates with VO 2 as an objective measure of stress. Surgical residents achieve stress levels of tachycardia during on-call periods that inversely reflect the training level of the residents. Phenotypic change was documented as an increase in leukocyte count. The stress of being “on call” is substantial enough to provoke measurable physiologic and phenotypic changes in surgery residents.

Introduction: The conventional view that admission lactate levels predict outcome in trauma patients stems from simple comparisons of mean blood levels between groups and small sample sizes. To better address this question, we performed more rigorous statistical analyses of lactate in a larger patient sample. Methods: We prospectively collected data on admission lactate and outcomes in 5,995 patients admitted to an urban, university-based trauma center. The ability of admission lactate to predict mortality was assessed by logistic regression, calculation of positive predictive values (PPV), and measurement of areas under receiver operating characteristic (ROC) curves. Results: Differences between survivors and nonsurvivors in means of most proposed prognosticators was again demonstrated. However, the large overlap in these variables between survivors and nonsurvivors prevented clinically useful predictions. The overall PPV of elevated lactate was only 5.4%. Even in severely injured patients (Injury Severity Score >20; mortality 23%), elevated admission lactate level was a poor predictor of outcome. ROC analyses found no useful sensitivity threshold overall or after stratification by age, sex, Glasgow Coma Scale score, revised trauma score, or mechanism of injury. Conclusions: This large retrospective examination of admission lactate levels failed to show useful predictive accuracy for hospital death. Serum lactate levels need not be obtained routinely but can be reserved for patients who will be admitted to the intensive care unit and/or require an emergency operation.

LPS stimulates gastric bicarbonate secretion and prevents gastric injury from acidified ethanol, possibly due to dilution and/or neutralization of this irritant. This study was conducted to determine the time course of LPS-induced alkaline secretion and its relationship with gastroprotection. The role of endogenous prostaglandins in gastroprotection was also examined. When compared to control conscious rats receiving saline, LPS (20 mg/kg IP) for 1, 2, or 3 hours, time dependently increased gastric luminal fluid accumulation (0A ± 0.08 vs. 0.55 ± 0.13, 2.1 ± 0,21, 2.6 ± 0.32 ml) and augmented gastric bicarbonate secretion (0.2 -+ 0.1 vs. 0.4 -+ 0.2, 1.6 ± 0.5, 2.3 ± 0.4 ~tEq). These LPS-induced effects were significantly (p -5/group) different from controls at 2 and 3 hours, but not at 1 hour. Thus, conscious rats received either saline or LPS for 1 hour and then were challenged with 1 ml of the luminal irritant acidified ethanol (150 mM HCI/50% ethanol) for 5 minutes. LPS reduced the magnitude of gastric mncosa involved with macroscopic damage (4.7 ± 1 vs. 15.3 ± 2%, p = 0.01) when analyzed by computerized planimetry. The gastroprotective effect of LPS was in turn negated by administration of the cyclooxygenase inhibitor aspirin (100 mg/kg IP) given 1 hour prior to LPS (14.4±2.6 vs. 4.5±0.1%, p=0.01). In the absence of acidified ethanol and using an enzyme linked immunoassay to measure endogenous prostaglandins, a 1-hour pretreatment with LPS also increased gastric mucosal levels of the prostacyclin metabolite, 6-keto-PGFla (1280±219 vs. 610~-186 pg/mg protein, p = 0.03) but did not enhance prostaglandin E 2 levels (2823 ± 437 vs. 2328 ± 230 pg/mg protein, p = NS) when compared to controls. Aspirin resulted in a 98% reduction in gastric mucosai prostaglandin levels. Consequently, these data suggest that LPSinduced gastroprotection cannot be fully explained by dilution as the protective response is present prior to any significant effect on bicarbonate secretion. Moreover, the mechanism responsible for this action is mediated in part by release of endogenous prostaglandins. This research was funded by NIGMS Grant GM 38529.