Dramatic Shift in the Primary Management of Traumatic Thoracic Aortic Rupture

HYPOTHESIS

Traumatic thoracic aortic injury (TAI) is traditionally treated with immediate surgery. Previously published studies have established the safety and efficacy of treating TAI with endovascular stents. Our hypothesis was that stents are supplanting operative repair as the primary therapy for TAI.

DESIGN

Retrospective cohort.

SETTING

University level I trauma center.

PATIENTS AND METHODS

Blunt trauma patients admitted to a level I trauma center diagnosed with TAI between September 1997 and November 2003 were identified from an institutional trauma registry (N = 25). Data were abstracted from medical records and analyzed. Three groups were defined: surgical repair (cardiopulmonary bypass or clamp and sew) (n = 10); medical management (n = 8); and endovascular stent (n = 7).

RESULTS

Prior to 2002, 9 (75%) of 12 patients were treated by surgical repair, 2 (17%) by medical management, and 1 (8%) by endovascular stent. Since 2002, 1 patient (8%) was treated by surgical repair, 6 (46%) by medical management, and 6 (46%) by endovascular stent. Injury Severity Scores were comparable between the surgical cohort (mean +/- SEM score, 34.9 +/- 3.4), stent placement (35.1 +/- 3.7), and medical management (29.9 +/- 2.8) (P = .48). Overall survival was 80% with no differences in morbidity or mortality. The stented group had shorter hospital lengths of stay compared with surgical management (28 vs 46 days) (P<.05). The 1 operative case since 2002 was a combined arch/innominate injury that anatomically precluded stent placement.

CONCLUSION

Initial reports suggested thoracic aortic stents as an alternative for injured patients with prohibitive operative risks. Our data suggest stent placement is quickly evolving into the primary therapy for TAI across all Injury Severity Score profiles.

Are temporary inferior vena cava filters really temporary?

BACKGROUND

Despite significant risk for venous thromboembolism, severely injured trauma patients often are not candidates for prophylaxis or treatment with anticoagulation. Long-term inferior vena cava (IVC) filters are associated with increased risk of postphlebitic syndrome. Retrievable IVC filters potentially offer a better solution, but only if the filter is removed; our hypothesis is that the most of them are not.

METHODS

This retrospective study queried a level I trauma registry for IVC filter insertion from September 1997 through June 2004.

RESULTS

One IVC filter was placed before the availability of retrievable filters in 2001. Since 2001, 27 filters have been placed, indicating a change in practice patterns. Filters were placed for prophylaxis (n = 11) or for therapy in patients with pulmonary embolism or deep vein thrombosis (n = 17). Of 23 temporary filters, only 8 (35%) were removed.

CONCLUSIONS

Surgeons must critically evaluate indications for IVC filter insertion, develop standard criteria for placement, and implement protocols to ensure timely removal of temporary IVC filters.

Education and training of the future trauma surgeon in acute care surgery: trauma, critical care, and emergency surgery

BACKGROUND

Trauma surgery as a specialty in the United States is at a crossroads. Currently, less than 100 residents per year pursue additional specialty training in trauma and surgical critical care. Many forces have converged to place serious challenges and obstacles to the training of future trauma surgeons. In order for the field to flourish, the training of future trauma surgeons must be modified to compensate for these changes.

DATA SOURCES

Recent medical literature regarding the training of trauma surgeons and report of the Future of Trauma Surgery/Trauma Specialization Committee of the American Association for the Surgery of Trauma.

CONCLUSIONS

The new post-graduate trauma training fellowship of the future should be built on a foundation of general surgery. The goal of this program will be to train a surgeon with broad expertise in trauma, critical care, and emergency general surgery. This new emphasis on non-trauma emergency surgery required an image change and thus a new name; Acute Care Surgery: Trauma, Critical Care, and Emergency Surgery.

Potential Targets to Encourage a Surgical Career

BACKGROUND

Our goal was to identify factors that can be targeted during medical education to encourage a career in surgery.

STUDY DESIGN

We conducted a cross-sectional survey of first and fourth year classes in a Liaison Committee on Medical Education-accredited medical school. Students scored 19 items about perceptions of surgery using a Likert-type scale. Students also indicated their gender and ranked their top three career choices.

RESULTS

There were 121 of 210 (58%) first year and 110 of 212 (52%) fourth year students who completed the survey. First year students expressed a positive correlation between surgery and career opportunities, intellectual challenge, performing technical procedures, and obtaining a residency position, although length of training, work hours, and lifestyle during and after training were negatively correlated with choosing surgery. Fourth year student responses correlated positively with career and academic opportunities, intellectual challenge, technical skills, role models, prestige, and financial rewards. Factors that correlated negatively were length of training, residency lifestyle, hours, call schedule, and female gender of the student respondent. Forty-four percent of first year male students expressed an interest in surgery versus 27% of fourth year male students (p < 0.04). Eighteen percent of first year female students expressed an interest in surgery versus 5% of fourth year female students (p < 0.006).

CONCLUSIONS

Lifestyle issues remain at the forefront of student concerns. Intellectual challenge, career opportunities, and technical skills are consistently recognized as strengths of surgery. Additionally, fourth year students identify role models, prestige, and financial rewards as positive attributes. Emphasizing positive aspects may facilitate attracting quality students to future careers in surgery.

Poor validity of residual volumes as a marker for risk of aspiration in critically ill patients

BACKGROUND AND AIMS

Elevated residual volumes (RV), considered a marker for the risk of aspiration, are used to regulate the delivery of enteral tube feeding. We designed this prospective study to validate such use.

METHODS

Critically ill patients undergoing mechanical ventilation in the medical, coronary, or surgical intensive care units in a university-based tertiary care hospital, placed on intragastric enteral tube feeding through nasogastric or percutaneous endoscopic gastrostomy tubes, were included in this study. Patients were fed Probalance (Nestle USA) to provide 25 kcal/kg per day (to which 10 yellow microscopic beads and 4.5 mL of blue food coloring per 1,500 mL was added). Patients were randomized to one of two groups based on management of RV: cessation of enteral tube feeding for RV >400 mL in study patients or for RV >200 mL in controls. Acute Physiology and Chronic Health Evaluation (APACHE) III, bowel function score, and aspiration risk score were determined. Bedside evaluations were done every 4 hrs for 3 days to measure RV, to detect blue food coloring, to check patient position, and to collect secretions from the trachea and oropharynx. Aspiration/regurgitation events were defined by the detection of yellow color in tracheal/oropharyngeal samples by fluorometry. Analysis was done by analysis of variance, Spearman's correlation, Student's t-test, Tukey's method, and Cochran-Armitage test.

RESULTS

Forty patients (mean age, 44.6 yrs; range, 18-88 yrs; 70% male; mean APACHE III score, 40.9 [range, 12-85]) were evaluated (21 on nasogastric, 19 on percutaneous endoscopic gastrostomy feeds) and entered into the study. Based on 1,118 samples (531 oral, 587 tracheal), the mean frequency of regurgitation per patient was 31.3% (range, 0% to 94%), with a mean RV for all regurgitation events of 35.1 mL (range, 0-700 mL). The mean frequency of aspiration per patient was 22.1% (range, 0% to 94%), with a mean RV for all aspiration events of 30.6 mL (range, 0-700 mL). The median RV for both regurgitation and aspiration events was 5 mL. Over a wide range of RV, increasing from 0 mL to >400 mL, the frequency of regurgitation and aspiration did not change appreciably. Aspiration risk and bowel function scores did not correlate with the incidence of aspiration or regurgitation. Blue food coloring was detected on only three of the 1,118 (0.27%) samples. RV was < or =50 mL on 84.1% and >400 mL on 1.4% of bedside evaluations. Sensitivities for detecting aspiration per designated RV were as follows: 400 mL = 1.5%; 300 mL = 2.3%; 200 mL = 3.0%; and 150 mL = 4.5%. Low RV did not assure the absence of events, because the frequency of aspiration was 23.0% when RV was <150 mL. Raising the designated RV for cessation of enteral tube feeding from 200 mL to 400 mL did not increase the risk, because the frequency of aspiration was no different between controls (21.6%) and study patients (22.6%). The frequency of regurgitation was significantly less for patients with percutaneous endoscopic gastrostomy tubes compared with those with nasogastric tubes (20.3% vs. 40.7%, respectively; p = .046). There was no correlation between the incidence of pneumonia and the frequency of regurgitation or aspiration.

CONCLUSIONS

Blue food coloring should not be used as a clinical monitor. Converting nasogastric tubes to percutaneous endoscopic gastrostomy tubes may be a successful strategy to reduce the risk of aspiration. No appropriate designated RV level to identify aspiration could be derived as a result of poor sensitivity over a wide range of RV. Study results do not support the conventional use of RV as a marker for the risk of aspiration.

Interleukin-6 Infusion Blunts Proinflammatory Cytokine Production Without Causing Systematic Toxicity in a Swine Model of Uncontrolled Hemorrhagic Shock

BACKGROUND

Serum elevations of interleukin-6 (IL-6) correlate with multiple organ dysfunction syndrome and mortality in critically injured trauma patients. Data from rodent models of controlled hemorrhage suggest that recombinant IL-6 (rIL-6) infusion protects tissue at risk for ischemia-reperfusion injury. Exogenous rIL-6 administered during shock appears to abrogate inflammation, providing a protective rather than a deleterious influence. In an examination of this paradox, the current study aimed to determine whether rIL-6 decreases inflammation in a clinically relevant large animal model of uncontrolled hemorrhagic shock, (UHS), and to investigate the mechanism of protection.

METHODS

Swine were randomized to four groups (8 animals in each): (1) sacrifice, (2) sham (splenectomy followed by hemodilution and cooling to 33 degrees C), (3) rIL-6 infusion (sham plus UHS using grade 5 liver injury with packing and resuscitation plus blinded infusion of rIL-6 [10 mcg/kg]), and (4) placebo (UHS plus blinded vehicle). After 4 hours, blood was sampled, estimated blood loss determined, animals sacrificed, and lung harvested for RNA isolation. Quantitative reverse transcriptase-polymerase chain reaction was used to assess granulocyte colony-stimulating factor (G-CSF), IL-6, and tumor necrosis factor-alpha (TNFalpha) messenger ribonucleic acid (mRNA) levels. Serum levels of IL-6 and TNFalpha were measured by enzyme-linked immunoassay (ELISA).

RESULTS

As compared with placebo, IL-6 infusion in UHS did not increase estimated blood loss or white blood cell counts, nor decrease hematocrit or platelet levels. As compared with the sham condition, lung G-CSF mRNA production in UHS plus placebo increased eightfold (*p < 0.05). In contrast, rIL-6 infusion plus UHS blunted G-CSF mRNA levels, which were not significantly higher than sham levels (p = 0.1). Infusion of rIL-6 did not significantly affect endogenous production of either lung IL-6 or mRNA. As determined by ELISA, rIL-6 infusion did not increase final serum levels of IL-6 or TNFalpha over those of sham and placebo conditions.

CONCLUSIONS

Exogenous rIL-6 blunts lung mRNA levels of the proinflammatory cytokine G-CSF. The administration of rIL-6 does not increase the local expression of IL-6 nor TNFalpha mRNA in the lung. Additionally, rIL-6 infusion does not appear to cause systemic toxicity.

Impairment of endothelium-dependent dilation response after resuscitation from hemorrhagic shock involved postreceptor mechanisms

Resuscitation from hemorrhagic shock is associated with impairment of the endothelium-dependent dilation response, whereas the dilation response induced by the endothelium-independent pathway, which is mediated by nitroprusside, a nitric oxide (NO) donor and a direct activator of guanylate cyclase, remains unaltered. Whether the impairment of the endothelium-dependent dilation response is caused by a specific receptor alteration or generally a defect in signal transduction pathway remains undetermined. Anesthetized rats were monitored for hemodynamics, and the terminal ileum was prepared for intravital videomicroscopy. Hemorrhage was 50% of mean arterial pressure for 60 min followed by resuscitation with the shed blood returned plus 2 volumes of normal saline. Intestinal microvascular reactivity to the endothelium-dependent receptor-dependent agonists acetylcholine or substance P (10(-8) or 10(-6) M), as well as the endothelium-dependent receptor-independent calcium ionophore, was determined at baseline and at 2 h postresuscitation from hemorrhagic shock. Measured vascular diameters for premucosal A3 arterioles (pA3 and dA3) were normalized and expressed as percentage of the maximal dilation capacity, as obtained from the response to the endothelium-independent NO donor sodium nitroprusside (10(-4) M). At 2 h postresuscitation, there was a marked constriction of pA3 (-70.1 +/- 20) and dA3 (-61.5 +/- 11.6) from maximal dilation capacity. Baseline premucosal arteriolar response to substance P (10(-8) M) was 30.68 +/- 4.19% and 34.66 +/- 5.82% for pA3 and dA3 arterioles, respectively. This was significantly reduced to 20.97 +/- 2.41% and 17.94 +/- 3.60% at 2 h postresuscitation. However, no significant difference between baseline and postresuscitation arteriolar responses was observed at the higher dose of substance P (10(-6) M). Postresuscitation premucosal arteriolar response to the endothelium-dependent receptor-independent calcium ionophore (10(-9) to 10(-5) M) is characterized by a marked decrease in sensitivity and an enhanced threshold for calcium ionophore-mediated dilation. The logEC50 was -7.62 +/- 0.39 and -7.75 +/- 0.32 for the pA3 and dA3 at baseline, respectively. This was significantly (P < 0.01) reduced to -5.15 +/- 0.14 and -4.39 +/- 0.71 at 2 h postresuscitation. These data suggest that impairment of the endothelium-dependent dilation response after resuscitation from hemorrhagic shock is not mediated by specific receptor alteration. Cellular mechanisms that participate in or are part of oxygen free radical formation after resuscitation from hemorrhagic shock such as Ca2+ and leukocytes, appear to have a pivotal role in the mechanism of cellular dysfunction.

The continuing challenge of intra-abdominal infection

Intra-abdominal infection is common and frequently seen by the surgeon. Mortality is related to disease acuity and organ failure. This report, based on medical literature and personal experience, is a brief review of this subject, highlighting important historical milestones and recent advances in surgical and antibiotic therapy. Peritonitis remains a clinical challenge. Aggressive resuscitation, diagnostic imaging, and surgical treatment are the mainstays of appropriate therapy. Percutaneous drainage of intra-abdominal collections has increased over time and is particularly helpful in certain postoperative patients. Adjunctive antibiotic therapy against gram-negative aerobes and anaerobes should be limited to a 7- to 10-day course, except in selected patients, such as those with inadequate source controls.

Intraperitoneal resuscitation improves intestinal blood flow following hemorrhagic shock

OBJECTIVE

To study the effects of peritoneal resuscitation from hemorrhagic shock.

SUMMARY BACKGROUND DATA

Methods for conventional resuscitation (CR) from hemorrhagic shock (HS) often fail to restore adequate intestinal blood flow, and intestinal ischemia has been implicated in the activation of the inflammatory response. There is clinical evidence that intestinal hypoperfusion is a major factor in progressive organ failure following HS. This study presents a novel technique of peritoneal resuscitation (PR) that improves visceral perfusion.

METHODS

Male Sprague-Dawley rats were bled to 50% of baseline mean arterial pressure (MAP) and resuscitated with shed blood plus 2 equal volumes of saline (CR). Groups were 1) sham, 2) HS + CR, and 3) HS + CR + PR with a hyperosmolar dextrose-based solution (Delflex 2.5%). Groups 1 and 2 had normal saline PR. In vivo videomicroscopy and Doppler velocimetry were used to assess terminal ileal microvascular blood flow. Endothelial cell function was assessed by the endothelium-dependent vasodilator acetylcholine.

RESULTS

Despite restored heart rate and MAP to baseline values, CR animals developed a progressive intestinal vasoconstriction and tissue hypoperfusion compared to baseline flow. PR induced an immediate and sustained vasodilation compared to baseline and a marked increase in average intestinal blood flow during the entire 2-hour post-resuscitation period. Endothelial-dependent dilator function was preserved with PR.

CONCLUSIONS

Despite the restoration of MAP with blood and saline infusions, progressive vasoconstriction and compromised intestinal blood flow occurs following HS/CR. Hyperosmolar PR during CR maintains intestinal blood flow and endothelial function. This is thought to be a direct effect of hyperosmolar solutions on the visceral microvessels. The addition of PR to a CR protocol prevents the splanchnic ischemia that initiates systemic inflammation.

Immune-enhancing enteral diet increases blood flow and proinflammatory cytokines in the rat ileum

BACKGROUND

Enteral feeding improves outcome following surgery. Benefits depend on timing, route (enteral vs parenteral), and nutrient composition (standard vs immune-enhancing diets; IED). IED augments intestinal immunity and stimulates gut blood flow during absorption in a nutrient-specific manner. We hypothesize that a mechanism for the gut protective effect of IED is augmentation of blood flow to the gut-associated lymphoid tissue (GALT) in the terminal ileum.

METHODS

Male Sprague-Dawley rats (200-230 g) were fed for 5 days either an IED (Impact, Novartis) or an isocaloric, isonitrogenous control diet (CD, Boost, Mead-Johnson) matched to the daily caloric intake (rat chow). Rats were then anesthetized and cannulated for microsphere determination of whole organ blood flow. Blood glucose levels and blood flow to abdominal organs were determined at baseline and 30, 60, 90, and 120 min after gastric gavage (2 ml) with IED or CD. Intestinal tissues were harvested for cytokine levels (ELISA: IL-4, IL-10, IFN-gamma, and IgA).

RESULTS

Chronic IED increased baseline blood flow in the distal third of the small intestine compared to chow-fed and CD. Baseline blood flow was comparable between IED and CD in all other organs. CD and IED produced different blood flow patterns after gavage. CD increased blood flow compared to baseline and IED in antrum, duodenum, and jejunum. Ileal blood flow remained elevated in IED rats for 2 h, perhaps suggesting maximal blood flow. IED increased blood glucose compared to CD. Chronic IED increased IL-4 and decreased IL-10 in the terminal ileum.

CONCLUSIONS

Chronic IED exposure increases and sustains ileal blood flow compared to CD with altered proinflammatory cytokine expression. Our data suggest that a mechanism for the IED effect involves the selective perfusion of the terminal ileum and contiguous GALT during IED nutrient absorption.

Achievement of steady state optimizes results when performing indirect calorimetry

BACKGROUND

The use of steady state as the endpoint for performance of indirect calorimetry (IC) is controversial. We designed this prospective study to evaluate the necessity and significance of achieving steady state.

METHODS

Patients with respiratory failure placed on mechanical ventilation in a short- or long-term acute care unit at any 1 of 3 university-based urban hospitals were eligible for the study. The 24-hour total energy expenditure (TEE) was determined by a Nellcor Puritan Bennett 7250 continuous IC monitor. Measured gas exchange parameters were obtained and averaged every 1 minute for the initial hour and then every 15 minutes for the next 23 hours. Over the initial hour, resting energy expenditure (REE) was averaged for intervals over the first 20, 30, 40, and 60 minutes, and for various definitions of steady state where oxygen consumption (VO2) and carbon dioxide production (VCO2) changed by <10%, 15%, and 20%. Coefficient of variation (CV) was calculated for VO2 over the first 30 minutes of study.

RESULTS

Twenty-two patients (mean age, 52.8 years, 59% male, mean Acute Physiology and Chronic Health Evaluation (APACHE III) score 42.0) were entered in the study. The best correlation between short-term "snapshot" REE and the 24-hour TEE was achieved by the steady-state period defined by the most stringent criteria (change in VO2 and VCO2 by <10%). The average REE for all steady-state and interval periods correlated significantly to TEE with no significant difference in the absolute values for REE and TEE. Adding 10% for an activity factor to the average REE for each steady-state and interval period again correlated to TEE in a similar fashion with the same R value, but the absolute values for REE + 10% for all steady-state and interval periods were significantly different than the corresponding TEE. In those patients with less variation (CV for VO2 < or = 9.0), the REE obtained for the steady-state period defined by the most stringent criteria still had the best correlation, but similar correlation could be obtained by interval testing of > or = 30-minute duration. In those patients with greater variation (CV for VO2 >9.0), interval testing of at least 60 minutes or more was required to attain levels of correlation similar to that achieved by the steady-state period defined by the most stringent criteria.

CONCLUSIONS

These data support the use of steady state, best defined as an interval of 5 consecutive minutes whereby VO2 and VCO2 change by <10%. The mean REE from this period correlates best to the 24-hour TEE regardless of CV. IC testing can be completed after achievement of steady state. Activity factors of 10% to 15% should not be added to the steady-state REE, because this practice significantly decreases the accuracy. In patients who fail to achieve steady state, the CV helps to determine the appropriate duration of IC testing. In those patients with a low CV (< or = 9.0), 30-minute test duration is adequate. In patients with CV >9.0, test duration of at least 60 minutes may be required. These latter patients should be considered for 24-hour IC testing.

Resuscitation regimens for hemorrhagic shock must contain blood

Endothelial cell dysfunction occurs during hemorrhagic shock (HS) and persists despite adequate resuscitation (RES) that restores and maintains hemodynamics. We hypothesize that RES from HS with crystalloid solutions alone aggravate the endothelial cell dysfunction. To test this hypothesis, anesthetized nonheparinized rats were monitored for hemodynamics, and the terminal ileum was studied with intravital video microscopy. HS was 50% of mean arterial pressure (MAP) for 60 min. Four hemorrhaged groups (10 animals in each group) were randomized for RES: group I with shed blood returned + equal volume of normal saline (NS); group II with shed blood returned + 2x NS; group III with 2x NS only; and group IV with 4x NS only. Two hours post-RES, endothelial cell function was assessed with the endothelial-dependent agonist acetylcholine (ACh, 10(-9)-10(-4) M). Maximum arteriolar diameter was elicited by the endothelial-independent agonist sodium nitroprusside (NTP, 10(-4) M). HS caused a selective vasoconstriction associated with low blood flow in inflow A1 arterioles in all hemorrhaged groups. Post-RES vasoconstriction developed in A1 and premucosal arterioles (pA3 and dA3) In all hemorrhaged groups regardless of the RES regimen. However, A1 vasoconstriction and flow were significantly worst in the animals RES with NS alone (-43% and -75%, respectively) compared with those resuscitated with blood and NS (-27% and -57%). Impaired dilation response to ACh was noted in all hemorrhaged animals. However, a significant shift to the right of the dose-response curve (decreased sensitivity) was observed in the animals resuscitated with NS alone irrespective of the RES volume. These animals required at least two orders of magnitude greater ACh concentration to produce a 20% dilation response. For all vessel types, Group II had the best preservation of endothelial cell function. In conclusion, HS causes a selective vasoconstriction of A1 arterioles, which was not observed in A3 vessels. RES from HS results in progressive vasoconstriction in all intestinal arterioles irrespective of the RES regimen. Crystalloid RES after HS does not restore hemodynamics to baseline and is associated with a marked endothelial cell dysfunction. Blood-containing RES regimens preserve and maintain hemodynamics and are associated with the least microvascular dysfunction. Therefore, regimens for RES from HS must contain blood. Endothelial cell dysfunction is not the sole etiologic factor of post-RES microvascular impairment.

Risk factors for delirium tremens in trauma patients

BACKGROUND

The development of delirium tremens (DT) is associated with significant morbidity and mortality. This study identifies characteristics in trauma patients that are predictive of DT.

METHODS

Data from 1,856 trauma patients who either developed DT (n = 105) or had a positive blood alcohol concentration but did not develop DT (n = 1,751) were collected from the trauma registry of a Level I trauma center. Odds ratios were used to measure the association between predictors and DT as an outcome and between DT and length of stay as an outcome.

RESULTS

Of seven significant (p < 0.05) predictors of DT, four were retained after stepwise logistic regression: age >40, white race, burn as a mechanism of injury and, as a negative predictor, motor vehicle collision as a mechanism of injury. The DT group stayed an average of 6.5 and 5.2 days longer in the hospital and the intensive care unit, respectively, than those in the control group.

CONCLUSION

It is possible to determine which intoxicated trauma patients are at increased risk for DT using the above predictors. Patients who develop DT have worse outcomes than those who do not. Whether routine DT prophylaxis would improve outcomes among those at increased risk for DT is unknown, but deserves further study.

North American Summit on Aspiration in the Critically Ill Patient: consensus statement

Aspiration is the leading cause of pneumonia in the intensive care unit and the most serious complication of enteral tube feeding (ETF). Although aspiration is common, the clinical consequences are variable because of differences in nature of the aspirated material and individual host responses. A number of defense mechanisms normally present in the upper aerodigestive system that protect against aspiration become compromised by clinical events that occur frequently in the critical care setting, subjecting the patient to increased risk. The true incidence of aspiration has been difficult to determine in the past because of vague definitions, poor assessment monitors, and varying levels of clinical recognition. Standardization of terminology is an important step in helping to define the problem, design appropriate research studies, and develop strategies to reduce risk. Traditional clinical monitors of glucose oxidase strips and blue food coloring (BFC) should no longer be used. A modified approach to use of gastric residual volumes and identification of clinical factors that predispose to aspiration allow for risk stratification and an algorhythm approach to the management of the critically ill patient on ETF. Although the patient with confirmed aspiration should be monitored for clinical consequences and receive supportive pulmonary care, ETF may be continued when accompanied by appropriate steps to reduce risk of further aspiration. Management strategies for treating aspiration pneumonia are based on degree of diagnostic certainty, time of onset, and host factors.

When is the seriously ill patient ready to be fed?

BACKGROUND

After assessing the critically ill patient for risk of aspiration, the clinician still must decide if the patient is ready to be fed. The goal is to identify critically ill patients who are likely to tolerate enteral nutrition and attempt to minimize complications.

METHODS

A synthesis of the both clinical and animal studies to identify factors related to patient readiness for enteral nutrition.

RESULTS

The key issue to be resolved is adequacy of resuscitation and restoration of mesenteric perfusion. Currently, there is no reliable clinical tool to measure gut perfusion. The best indicators currently are stabilization of vital signs, decreasing fluid and blood requirements, normalization of the base deficit, and lactate and removal of inotropic or vasopressor support.

CONCLUSIONS

Most critically ill patients should be ready for enteral nutrition within 24 to 48 hours of intensive care unit admission. Critically ill patients who need catecholamine support, heavy sedation, or therapeutic neuromuscular blockade should probably not receive enteral nutrition until they have been stabilized.

Examination of the role of abdominal computed tomography in the evaluation of victims of trauma with increased aspartate aminotransferase in the era of focused abdominal sonography for trauma

BACKGROUND

Current evaluation of patients with negative findings on a focused abdominal sonography for trauma scan and an isolated increase of admission hepatic enzymes includes abdominal computed tomography (CT). Many of these patients do not have clinically important hepatic injuries. The purpose of this study was to establish the admission aspartate aminotransferase (AST) level below which patients do not need an abdominal CT for injury evaluation and treatment.

METHODS

Patients who were hemodynamically stable, had a focused abdominal sonography for trauma scan with negative findings, and an AST level greater than 200 IU/L were identified over a 1-year period. Medical records were reviewed for demographics, injuries sustained, mechanism, evaluation, interventions, and complications.

RESULTS

A total of 67 patients, mostly with blunt trauma, were identified; 42 (63%) had an AST level < 360 IU/L, and 25 (37%) had an AST level > 360 IU/L. Patients with an AST level > 360 IU/L had a 88% chance of having any hepatic injury and a 44% chance of having an injury of grade III or greater (P =.0001). Patients with an AST level of < 360 IU/L only had a 14% chance of having a liver injury and no chance of having an injury of grade III or greater (P =.036).

CONCLUSIONS

Clinically important hepatic injuries are not missed if an abdominal CT is only performed for patients with a focused abdominal sonography for trauma scan with negative findings and an AST level of > 360 IU/L. Eliminating unnecessary CT allows for more cost-effective use of resources.

Reevaluation of diagnostic procedures for transmediastinal gunshot wounds

BACKGROUND

Little controversy surrounds the treatment of hemodynamically unstable patients with transmediastinal gunshot wounds (TMGSWs). These patients generally have cardiac or major vascular injuries and require immediate operation. In hemodynamically stable patients, debate surrounds the extent and order of the diagnostic evaluation. These patients can be uninjured, or can have occult vascular, esophageal, or tracheobronchial injuries. Evaluation has traditionally often included angiography, bronchoscopy, esophagoscopy, esophagography, and pericardial evaluation (i.e., pericardial window) for all hemodynamically stable patients with TMGSWs. Expansion of the use of computed tomographic (CT) scanning in penetrating injury led to a modification of our protocol. Currently, our TMGSW evaluation algorithm for stable patients consists of chest radiograph, focused abdominal sonography for trauma, and contrast-enhanced helical CT scan of the chest with directed further evaluation. The purpose of this study is to evaluate the efficiency of contrast-enhanced helical CT scan for evaluating potential mediastinal injuries and to determine whether patients can be simply observed or require further investigational studies.

METHODS

Medical records of hemodynamically stable patients admitted with TMGSWs over a 2-year period were reviewed for demographics, mechanism of injury, method of evaluation, operative interventions, injuries, length of stay, and complications. CT scans were considered positive if they contained a mediastinal hematoma or pneumomediastinum, or demonstrated proximity of the missile track to major mediastinal structures.

RESULTS

Twenty-two stable patients were studied. CT scans were positive in seven patients. Directed further diagnostic evaluation in those seven patients revealed two patients who required operative intervention. Sixty-eight percent of patients had negative CT scans and were observed in a monitored setting without further evaluation. There were no missed injuries. The hospital charges generated with the CT scan-based protocol are significantly less than with the standard evaluation.

CONCLUSION

Contrast-enhanced helical CT scanning is a safe, efficient, and cost-effective diagnostic tool for evaluating hemodynamically stable patients with mediastinal gunshot wounds. Positive CT scan results direct the further evaluation of potentially injured structures. Patients with negative results can safely be observed in a monitored setting without further evaluation.

Generalized dilation of the visceral microvasculature by peritoneal dialysis solutions

OBJECTIVES

Conventional peritoneal dialysis solutions are vasoactive. This vasoactivity is attributed to hyperosmolality and lactate buffer system. This study was conducted to determine if the vasodilator property of commercial peritoneal dialysis solutions is a global phenomenon across microvascular levels, or if this vasodilation property is localized to certain vessel types in the small intestine.

DESIGN

Experimental study in a standard laboratory facility.

INTERVENTIONS

Hemodynamics of anesthetized rats were monitored while the terminal ileum was prepared for in vivo intravital microscopy. Vascular reactivity of inflow arterioles (A1), branching (A2), and arcade, as well as pre-mucosal (A3) arterioles was assessed after suffusion of the terminal ileum with a non-vasoactive solution or a commercial 4.25% glucose-based solution (Delflex; Fresenius USA, Ogden, Utah, USA). Vascular reactivity of three different level venules was also assessed. Maximum dilation response was obtained from sequential applications of the endothelial-dependent dilator, acetylcholine (10(-5) mol/L), and the endothelial-independent nitric oxide donor, sodium nitroprusside (NTP; 10(-4) mol/L).

RESULTS

Delflex induced an instant and sustained vasodilation that averaged 28.2% +/- 2.4% of baseline diameter in five different-level arterioles, ranging in size between 7 mu and 100 mu. No significant vascular reactivity was observed in three different-level venules. Delflex increased intestinal A1 blood flow from baseline 568 +/- 31 nL/ second to 1,049 +/- 46 nL/sec (F= 24.7, p< 0.001). Similarly, intestinal venous outflow increased to 435 +/- 17 nL/sec from a baseline outflow of 253 +/- 59 nL/sec (F= 4.7, p < 0.05). Adjustment of the initial pH of Delflex from 5.5 to 7.4 resulted in similar microvascular responses before pH adjustment.

CONCLUSIONS

Ex vivo exposure of intestinal arterioles to conventional peritoneal dialysis solutions produces a sustained and generalized vasodilation. This vasoactivity is independent of arteriolar level and the pH of the solution. Dialysis solution-mediated vasodilation is associated with doubling of A1 intestinal arteriolar blood flow. Addition of NTP at an apparent clinical dose does not appear to produce any further significant arteriolar dilation than that induced by dialysis solution alone. Experimental data that estimate the exchange vessel surface area per unit volume of tissue will be required to make a correlation with permeability in order to extrapolate our findings to clinical in vivo conditions.

A novel approach to the problem of intestinal fistulization arising in patients managed with open peritoneal cavities

Open management of the peritoneal cavity is an efficacious technique for controlling fulminant intraabdominal sepsis. A significant proportion of these patients develop intestinal fistulae for which there are few good treatment options. We propose a novel technique for preventing and potentially treating intestinal fistulas that involves patching intestinal deserosalizations and fistulas with acellular dermal matrix (Alloderm) and fibrin glue. We report our experience with this technique in 2 patients who developed small bowel deserosalizations, neither of whom went on to develop fistulas. We additionally describe 1 patient who developed an intestinal fistula for whom we were able to affect closure with this technique. We propose that our method is a useful temporizing measure to prevent fistulae formation. Furthermore, we believe this technique may be a useful option for treating intestinal fistulae arising in patients managed with open abdominal wounds.

Immune-enhancing enteral diet selectively augments ileal blood flow in the rat

BACKGROUND

Clinical studies show that immune-enhancing enteral diets (IED; with L-arginine, fish oil, and RNA fragments) decrease the rate of sepsis and shorten the length of hospital stay after the start of enteral feeding. These beneficial effects are dependent on the route of administration (enteral vs parenteral) and on the nutrient composition (IED vs standard diets). Gut exposure to an IED seems to preserve and/or augment intestinal mucosal immunity. However, nutrient absorption stimulates gut blood flow in a nutrient-specific manner (i.e., postprandial hyperemia). We hypothesized that an IED would initiate a different pattern of whole organ blood flow compared to a standard diet. This suggests that a mechanism for the protective effect of IED might be the preferential augmentation of gut blood flow to gut-associated lymphoid tissue (GALT) or mucosa-associated lymphoid tissue (MALT).

METHODS

Male Sprague-Dawley rats (200-225 g) were anesthetized and cannulated for colorimetric microsphere determination of blood flow distribution (with the phantom organ technique). Animals received gastric gavage (2 ml) of an IED (Impact; Novartis) or an isocaloric, isonitrogenous control diet (Boost; Mead-Johnson). Blood flow to the antrum, duodenum, jejunum, ileum, colon, liver, kidneys, and spleen was determined at baseline and 30, 60, 90, and 120 min after gavage.

RESULTS

Baseline blood flows to the left and right kidneys were within 10%, indicating the technical integrity of the microsphere technique and assay. Control diet augmented blood flow compared to IED in the antrum, duodenum, jejunum, and spleen. Conversely, IED gavage stimulated a delayed and sustained hyperemic response in the ileum. IED also increased hepatic blood flow early (30 min). IED increased blood glucose levels compared to control diet at 30, 60, and 90 min, suggesting enhanced nutrient absorption.

CONCLUSIONS

These data show that blood flow distribution depends on nutrient composition and that IED preferentially augments blood flow to the ileum. Since the terminal jejunum and ileum contain much of the GALT, our data suggest that a mechanism for enterally stimulated mucosal immunity involves selective perfusion of the terminal ileum during IED nutrient absorption.

Abdominal seat belt marks in the era of focused abdominal sonography for trauma

HYPOTHESIS

Focused abdominal sonography for trauma (FAST) is an unreliable method for assessing intra-abdominal injury in patients with seat belt marks.

DESIGN

Retrospective review of trauma patients with intestinal injury and seat belt marks during a 3-year period. Records were reviewed for patient demographics, FAST results, computed tomographic (CT) scan results, and operative findings. The CT scan results were considered positive if bowel wall thickening, extraluminal air, or free fluid without solid organ injury were present.

SETTING

University hospital designated as a level I trauma center.

PATIENTS

Twenty-three patients who required operation for intestinal or mesenteric injury and who had an abdominal seat belt mark.

MAIN OUTCOME MEASURE

Sensitivity of FAST in these patients.

RESULTS

All patients were evaluated using both FAST and CT scan of the abdomen and pelvis. Eighteen patients (78%) had either negative or equivocal FAST results when significant intestinal injury was present. All 23 patients had CT scan findings suggestive of bowel or mesenteric injury. Moderate-to-large free intraperitoneal fluid without solid organ injury was the most common finding (n = 21, 91%). Operative findings included small-bowel perforation (n = 18, 78%), colonic perforation (n = 7, 30%), bowel deserosalization (n = 8, 35%), and isolated mesenteric injury (n = 5, 22%). Sixteen patients (70%) had multiple intra-abdominal injuries. All patients were taken directly from the emergency department to the operating room. Seventeen percent of operative explorations (4/23) were nontherapeutic (no repairs required).

CONCLUSION

This study confirms that FAST cannot reliably exclude intestinal injury in patients with seat belt marks.

A comparison of alcohol-positive and alcohol-negative trauma patients

OBJECTIVE

Hospital admission for an alcohol-related traumatic injury may offer a "teachable moment" to address a patient's alcohol problem. Although trauma teams provide a number of other health-related services, there may be characteristics of alcohol-positive victims that act as barriers toward providing alcohol counseling. The purpose of this study was to compare the characteristics and hospital outcomes of trauma patients who tested positive for alcohol at the time of hospital admission with those who did not. This information is useful for planning interventions and referrals for treatment.

METHOD

The study was a retrospective comparison of alcohol-positive and alcohol-negative patients who were admitted for at least 48 hours to a Level-I trauma center. Data from 1,049 trauma victims (736 male, 742 alcohol-negative) were abstracted from clinical records.

RESULTS

Several characteristics were found to be associated with alcohol-related injuries: being male, aged 40 years or less, having a toxicology screen positive for illicit drugs, lacking health insurance, being indigent and sustaining an injury related to violence. Alcohol-positive patients were also found to spend fewer days in a critical care unit, to be less likely to die and to be less likely to be transferred to another hospital than alcohol-negative patients, despite having similar injury severity.

CONCLUSIONS

Patient characteristics suggest that there are obstacles to providing interventions and referrals by healthcare professionals for victims of alcohol-related injuries. Less expensive options that consider the demographic features of this patient population need to be developed as an alternative to expensive, professional interventions.

Do Facial Fractures Protect the Brain or are they a Marker for Severe Head Injury?

Facial fractures (FF) have been suggested to protect the brain from severe injury. However, others have stated that facial fractures are a marker for increased risk of brain injury. The aim of this study is to evaluate the association between facial fractures, brain injury, and functional outcome. A retrospective review of our prospective trauma database was performed for blunt trauma patients during a 7-year period (January 1993 through December 1999) at the University of Louisville Hospital. We identified 7324 blunt trauma patients at a Level 1 trauma center. Severity of head injury in patients with and without FF was compared. The severity of brain injury was evaluated by admission Glasgow Coma Score (GCS) as well as specific head, neck, cervical spine, and face Acute Injury Score (AIS). Length of intensive care unit (ICU) stay, hospital stay, and Functional Independence Measures (FIM) score were also identified. A total of 1068 (14.6%) patients were diagnosed with FF; of these 848 (79.4%) patients suffered some form of brain injury by CT abnormality, clinical examination, or both. A total of 2192 patients were treated for head injury without FF; 220 patients were treated for FF without head injury. FF with traumatic brain injury (TBI) were found to occur significantly greater than FFs without TBI ( P < 0.001). The mean GCS on admission for FF with head injury was 12, which was similar to that of patients with head injury alone with a GCS of 10 but was significantly less than that of patients with FF alone with a GCS of 15 ( P < 0.05). Injury Severity Score for patients with FF and head injury was significantly worse compared with patients with head injury alone and those with FF alone ( P < 0.0001). Mean ICU stay and hospital stay were similar for all three groups (ranges 3–6 and 6–12 days); and were not significant ( P < 0.06). FIM score was significantly lower for patients with FF and head injury compared with FF alone ( P = 0.0003) and similar to that of patients with head injury. FF were found to have a significantly greater incidence of TBI. FF with TBI had a similar severity of head injury when compared with patients with head injury alone by demonstrating similar GCS, AIS of the head and neck, and early functional recovery. This analysis does not support the hypothesis that the face provides a protective effect for the brain and therefore leading to a more favorable short-term outcome. Thus patients with facial fractures should be treated with the same caution as patients with significant blunt head trauma.

Do facial fractures protect the brain or are they a marker for severe head injury?

Facial fractures (FF) have been suggested to protect the brain from severe injury. However, others have stated that facial fractures are a marker for increased risk of brain injury. The aim of this study is to evaluate the association between facial fractures, brain injury, and functional outcome. A retrospective review of our prospective trauma database was performed for blunt trauma patients during a 7-year period (January 1993 through December 1999) at the University of Louisville Hospital. We identified 7324 blunt trauma patients at a Level 1 trauma center. Severity of head injury in patients with and without FF was compared. The severity of brain injury was evaluated by admission Glasgow Coma Score (GCS) as well as specific head, neck, cervical spine, and face Acute Injury Score (AIS). Length of intensive care unit (ICU) stay, hospital stay, and Functional Independence Measures (FIM) score were also identified. A total of 1068 (14.6%) patients were diagnosed with FF; of these 848 (79.4%) patients suffered some form of brain injury by CT abnormality, clinical examination, or both. A total of 2192 patients were treated for head injury without FF; 220 patients were treated for FF without head injury. FF with traumatic brain injury (TBI) were found to occur significantly greater than FFs without TBI (P < 0.001). The mean GCS on admission for FF with head injury was 12, which was similar to that of patients with head injury alone with a GCS of 10 but was significantly less than that of patients with FF alone with a GCS of 15 (P < 0.05). Injury Severity Score for patients with FF and head injury was significantly worse compared with patients with head injury alone and those with FF alone (P < 0.0001). Mean ICU stay and hospital stay were similar for all three groups (ranges 3-6 and 6-12 days); and were not significant (P < 0.06). FIM score was significantly lower for patients with FF and head injury compared with FF alone (P = 0.0003) and similar to that of patients with head injury. FF were found to have a significantly greater incidence of TBI. FF with TBI had a similar severity of head injury when compared with patients with head injury alone by demonstrating similar GCS, AIS of the head and neck, and early functional recovery. This analysis does not support the hypothesis that the face provides a protective effect for the brain and therefore leading to a more favorable short-term outcome. Thus patients with facial fractures should be treated with the same caution as patients with significant blunt head trauma.

Femoral vessel injuries

Early diagnosis, expeditious vascular repair, and aggressive management of complications have resulted in an amputation rate of less than 9%. Repair rather than ligation of an associated femoral vein injury is commonly practiced by experienced trauma surgeons. In most circumstances, a reversed autogenous saphenous vein graft from the contralateral extremity is the conduit of choice; however, if a saphenous vein cannot be used because of size discrepancies, multiple associated trauma, or extensive contamination, polytetrafluoroethylene can be used with good results. If vein ligation is performed, early fasciotomy is indicated for close and meticulous monitoring of the compartmental pressures. Clearly, the most crucial components for a successful outcome are a thorough evaluation, early operation, and a flawless vascular repair.

Handsewn versus stapled anastomosis in penetrating colon injuries requiring resection: a multicenter study

BACKGROUND

Although the use of stapling devices in elective colon surgery has been shown to be as safe as handsewn techniques, there have been concerns about their safety in emergency trauma surgery. The purpose of this study was to compare stapled with handsewn colonic anastomosis following penetrating trauma.

METHODS

This was a prospective multicenter study and included patients who underwent colon resection and anastomosis following penetrating trauma. Multivariate logistic regression analysis was used to identify independent risk factors for abdominal complications and compare outcomes between stapled and handsewn repairs.

RESULTS

Two hundred seven patients underwent colon resection and primary anastomosis. In 128 patients (61.8%) the anastomosis was performed with handsewing and in the remaining 79 (38.2%) with stapling devices. There were no colon-related deaths and the overall incidence of colon-related abdominal complications was 22.7% (26.6% in the stapled group and 20.3% in the handsewn group, p = 0.30). The incidence of anastomotic leak was 6.3% in the stapled group and 7.8% in the handsewn group (p = 0.69). Multivariate analysis adjusting for blood transfusions, fecal contamination, and type of antibiotic prophylaxis showed that the adjusted odds ratio (OR) of complications in the stapled group was 0.83 (95% CI, 0.38-1.74, p = 0.63). In a second multivariate analysis adjusting for blood transfusions, hypotension, fecal contamination, Penetrating Abdominal Trauma Index, and preoperative delays the adjusted OR in the stapled group was 0.99 (95% CI, 0.46-2.11, p = 0.99).

CONCLUSION

The results of this study suggest that the method of anastomosis following colon resection for penetrating trauma does not affect the incidence of abdominal complications and the choice should be surgeon's preference.

Thermal injury in the elderly: when is comfort care the right choice?

The factors contributing to a higher mortality rate in elderly thermal injury victims are not well delineated. The purpose of this study is to determine the impact of the initial injury, medical comorbidities, and burn size on patient outcome and to determine a level of injury in this population when comfort care is an appropriate first choice. Individual medical records of patients over 65 years of age admitted to our burn center over a 10-year interval were reviewed for patient demographics, mechanism of injury, total body surface area (TBSA) burned, medical comorbidities, use of Swan-Ganz catheters, evidence of inhalation injury, level of support, and patient outcome. The mechanisms of thermal injury were flame (68%), scald (21%) and electrical or chemical contact (11%). Twenty-six preventable bathing, cooking, and smoking-related injuries were seen (33%). The average TBSA was 25 per cent. Average length of stay varied depending on outcome. The overall mortality rate for this group was 45 per cent. Patients older than 80 years with 40 per cent or greater TBSA burned had a 100 per cent mortality rate despite aggressive treatment. Burn wound size correlated better with probability of poor outcome than age. Thermal injuries in the elderly are becoming more important with the aging of our population. Underlying medical problems--specifically chronic obstructive pulmonary disease--do play a role in increased patient morbidity and mortality. This study shows that age greater than 80 years in combination with burns greater than 40 per cent TBSA are uniformly fatal despite aggressive therapy. We believe that delaying the start of comfort-only measures in this situation only prolongs the pain and suffering for the patient, the family, and the physician.

Progressive decrease in constrictor reactivity of the non-absorbing intestine during chronic sepsis

Chronic sepsis leads to an impaired intestinal microcirculation, which might reflect altered microvascular control. We hypothesized that intestinal microvascular sensitivity to norepinephrine (NE) is decreased during chronic sepsis. Chronic sepsis was induced by a polymicrobial inoculation of implanted subcutaneous sponges in rats. Septic rats were studied either 24 or 72 h after a single inoculation (1-hit) of bacteria. Other rats received a second inoculation (2-hit) of bacteria 48 h later and were studied at 24 h after the second inoculation. NE (0.01-1.0 microM) responses in the non-absorbing terminal ileal arterioles (inflow A1, proximal-p and distal-d premucosal A3) were measured by video microscopy. NE threshold sensitivity (pD(T20) = -log of 20% response dose) was analyzed. pD(T20) was significantly decreased in A1, pA3, and dA3 of 1-hit 24-h septic rats (P < 0.05), and was further decreased in all vessels of 2-hit 72-h septic rats (P < 0.05). In contrast, the pDT(T20) of all three vessels significantly returned toward normal values after 72 h in rats that had only 1 bacteria inoculation. We conclude that an initial bacterial challenge decreases vasoconstrictor reactivity of the intestinal microcirculation and that subsequent repeated bacterial challenge exacerbates this defect in vasoconstrictor control in the non-absorbing intestine.

Thermal Injury in the Elderly: When is Comfort Care the Right Choice?

The factors contributing to a higher mortality rate in elderly thermal injury victims are not well delineated. The purpose of this study is to determine the impact of the initial injury, medical comorbidities, and burn size on patient outcome and to determine a level of injury in this population when comfort care is an appropriate first choice. Individual medical records of patients over 65 years of age admitted to our burn center over a 10-year interval were reviewed for patient demographics, mechanism of injury, total body surface area (TBSA) burned, medical comorbidities, use of Swan-Ganz catheters, evidence of inhalation injury, level of support, and patient outcome. The mechanisms of thermal injury were flame (68%), scald (21%) and electrical or chemical contact (11%). Twenty-six preventable bathing, cooking, and smoking-related injuries were seen (33%). The average TBSA was 25 per cent. Average length of stay varied depending on outcome. The overall mortality rate for this group was 45 per cent. Patients older than 80 years with 40 per cent or greater TBSA burned had a 100 per cent mortality rate despite aggressive treatment. Burn wound size correlated better with probability of poor outcome than age. Thermal injuries in the elderly are becoming more important with the aging of our population. Underlying medical problems—specifically chronic obstructive pulmonary disease—do play a role in increased patient morbidity and mortality. This study shows that age greater than 80 years in combination with burns greater than 40 per cent TBSA are uniformly fatal despite aggressive therapy. We believe that delaying the start of comfort-only measures in this situation only prolongs the pain and suffering for the patient, the family, and the physician.

Penetrating colon injuries requiring resection: diversion or primary anastomosis? An AAST prospective multicenter study

BACKGROUND

The management of colon injuries that require resection is an unresolved issue because the existing practices are derived mainly from class III evidence. Because of the inability of any single trauma center to accumulate enough cases for meaningful statistical analysis, a multicenter prospective study was performed to compare primary anastomosis with diversion and identify the risk factors for colon-related abdominal complications.

METHODS

This was a prospective study from 19 trauma centers and included patients with colon resection because of penetrating trauma, who survived at least 72 hours. Multivariate logistic regression analysis was used to compare outcomes in patients with primary anastomosis or diversion and identify independent risk factors for the development of abdominal complications.

RESULTS

Two hundred ninety-seven patients fulfilled the criteria for inclusion and analysis. Overall, 197 patients (66.3%) were managed by primary anastomosis and 100 (33.7%) by diversion. The overall colon-related mortality was 1.3% (four deaths in the diversion group, no deaths in the primary anastomosis group, p = 0.012). Colon-related abdominal complications occurred in 24% of all patients (primary repair, 22%; diversion, 27%; p = 0.373). Multivariate analysis including all potential risk factors with p values < 0.2 identified three independent risk factors for abdominal complications: severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis. The type of colon management was not found to be a risk factor. Comparison of primary anastomosis with diversion using multivariate analysis adjusting for the above three identified risk factors or the risk factors previously described in the literature (shock at admission, delay > 6 hours to operating room, penetrating abdominal trauma index > 25, severe fecal contamination, and transfusion of > 6 units blood) showed no statistically significant difference in outcome. Similarly, multivariate analysis and comparison of the two methods of colon management in high-risk patients showed no difference in outcome.

CONCLUSION

The surgical method of colon management after resection for penetrating trauma does not affect the incidence of abdominal complications, irrespective of associated risk factors. Severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis are independent risk factors for abdominal complications. In view of these findings, the reduced quality of life, and the need for a subsequent operation in colostomy patients, primary anastomosis should be considered in all such patients.

Impact of recent trends of noninvasive trauma evaluation and nonoperative management in surgical resident education

BACKGROUND

The use of ultrasonography and nonoperative management of solid organ injury has become standard practice in many trauma centers. Little is known about the effects of these changes on resident educational experience.

METHODS

We retrospectively reviewed resident evaluation of abdominal trauma and trauma operative experience as reported to the residency review committee between 1994 and 1999.

RESULTS

A total of 4,052 patients underwent one or more of three diagnostic modalities. The nontherapeutic laparotomy rate as a result of positive diagnostic peritoneal lavages decreased from 35% to 14%. Although resident operative trauma experience was stable because of increases in operative burns and nonabdominal trauma, the number of abdominal procedures declined.

CONCLUSION

Noninvasive diagnostic tests have allowed more rapid trauma evaluation and fewer nontherapeutic laparotomies. As nonoperative experience grows, the opportunity for operative experience decreases. These trends may adversely affect the education of residents and suggest that novel approaches are needed to ensure adequate operative experience in trauma.

Development and implementation of a clinical pathway for spinal cord injuries

The authors have developed a clinical pathway for the treatment of spinal cord injuries to help improve patient care. A clinical pathway for the treatment of patients with spinal cord injury was developed through a multidisciplinary approach. The control group (group 1) consisted of patients who were treated in the 2 years before the initiation of the pathway. Data from patients treated in conjunction with this pathway were collected prospectively (group 2). Thirty-six patients were treated in conjunction with the pathway compared with 22 in the control group. Group 2 had 6.8 fewer intensive care unit days, 11.5 fewer hospital days, 6 fewer ventilator days (p < 0.05), and a lower rate of complications. The use of a clinical care pathway for spinal cord injuries has resulted in improved patient care and fewer complications.

Successful incorporation of the Severe Head Injury Guidelines into a phased-outcome clinical pathway

Clinical pathways have been proven to be valuable tools in improving outcomes in patients with neurological diagnoses. However, their use with trauma populations has been limited. The unpredictable nature of trauma makes it difficult to develop a day-by-day plan of care that would be applicable to all patients with the same trauma diagnosis. Nevertheless, a severe traumatic brain injury (TBI) clinical pathway was developed and implemented at a Level 1 Trauma Center with significant reductions in length of stay and number of ventilator days. With the publication of the Guidelines for the Management of Severe Head Injury, this pathway was refashioned into a severe TBI phased-outcome pathway. Rather than a day-by-day plan of care, this clinical pathway consists of four phases of care: (a) admission to the intensive care unit, (b) acute critical care, (c) mobility and weaning, and (d) pre-rehabilitation. After 12 months, the improvements accomplished by the original pathway have been maintained or exceeded.

A multicenter evaluation of whether gender dimorphism affects survival after trauma

BACKGROUND

The frequency of women who have sustained severe injuries has increased over the past 30 years. The purpose of this study was to evaluate whether severely injured women have a survival advantage over men. To address this issue, we undertook a multicenter evaluation of the effects of gender dimorphism on survival in trauma patients.

METHODS

Patient information was collected from the databases of three level I trauma centers. We included all consecutive patients who were admitted to these centers over a 4-year period. We evaluated the effects of age, gender, mechanism of injury, pattern of injury, Abbreviated Injury Score (AIS), and Injury Severity Score (ISS) on survival.

RESULTS

A total of 20,261 patients were admitted to the three trauma centers. Women who were younger than 50 years of age (mortality rate 5%) experienced a survival advantage over men (mortality rate 7%) of equal age (odds ratio 1.27, P <0.002). This advantage was most notably found in the more severely injured (ISS >25) group (mortality rate 28% in women versus 33% in men). This difference was not attributable to mechanism of injury, severity of injury, or pattern of injury.

CONCLUSIONS

Severely injured women younger than 50 years of age have a survival advantage when compared with men of equal age and injury severity. Young men have a 27% greater chance of dying than women after trauma. We conclude that gender dimorphism affects the survival of patients after trauma.

Sepsis increases NOS-2 activity and decreases non-NOS-mediated acetylcholine-induced dilation in rat aorta

INTRODUCTION

Acetylcholine (Ach) is frequently used to assess endothelium-dependent vasodilation during sepsis. However, the effects of sepsis on constitutive nitric oxide synthase activity (NOS-1 and -3) and other non-NOS effects of Ach are unclear.

METHODS

Sepsis was induced in rats by inoculation of an implanted sponge with Escherichia coli and Bacteroides fragilis (10(9) CFU each). Thoracic aortic rings (2 mm) were harvested at 24 h from septic (N = 9) and control (N = 9) rats and were suspended in physiological salt solution (PSS), PSS + l-N(6)-(1-iminoethyl)lysine (l-NIL: NOS-2 inhibitor, 10 microM), or PSS + l-N(G)-monomethylarginine (l-NMMA: NOS-1, -2, and -3 inhibitor, 60 microM). Rings were set at 1-g preload and precontracted with phenlyephrine (10(-8) M). Relaxation dose-response curves were generated with six doses of Ach (3 x 10(-8) to 10(-5) M).

RESULTS

Sepsis increased the maximal relaxation to Ach under basal conditions. NOS 2 inhibition with l-NIL decreased Ach-induced relaxation in controls (66% vs 84%, P < 0.05, two-way ANOVA) and more so in septic rats (44% vs 93%, P < 0.05). Total NOS inhibition with l-NMMA decreased Ach-induced relaxation to 45% (P < 0.05) in controls and to 30% (P < 0.05) in septic animals.

CONCLUSIONS

Inhibition of NOS-1, -2, and -3 failed to abolish Ach-induced relaxation, suggesting the presence of other Ach-induced vasodilator mechanisms. NOS-2 inhibition reduced Ach-induced relaxation by 20-25% in the normal thoracic aorta, but by 50% in septic animals. The remaining Ach-induced non-NOS vasodilation (after inhibition of NOS-1 + NOS-2 + NOS-3) was reduced from 45% in normals to 30% in septic animals. Vascular dysregulation in sepsis is a complex event involving increased NOS-2, decreased NOS-1 + NOS-3, and decreased Ach-induced non-NOS vasodilator mechanisms.

Delayed laparoscopy facilitates the management of biliary peritonitis in patients with complex liver injuries

BACKGROUND

Nonoperative management is now regarded as the best alternative for the treatment of patients with complex blunt liver injuries. However, some patients still require surgical treatment for complications that were formerly managed with laparotomy and a combination of image-guided studies.

METHODS

We reviewed the medical records of 15 patients who had complex blunt liver injuries that were managed nonoperatively and in which biliary peritonitis developed.

RESULTS

Delayed laparoscopy was performed 2-9 days after admission in patients with extensive liver injuries. All 15 patients had developed local signs of peritonitis or a systemic inflammatory response. Laparoscopy was indicated to drain a large retained hemoperitoneum (eight patients), bile peritonitis (four patients), or an infected perihepatic collection (three patients). Laparoscopy was successful in all patients, and there was no need for further interventions.

CONCLUSION

The data indicate that as more patients with complex liver injuries are treated nonoperatively and the criteria for nonoperative management continue to expand, more patients will need some type of interventional procedure to treat complications that historically were managed by laparotomy. At this point, laparoscopy is an excellent alternative that should become part of the armamentarium of the trauma surgeons who treat these patients.

Does Cell-Saver Blood Administration and Free Hemoglobin Load Cause Renal Dysfunction?

Our aim was to evaluate the impact of cell-saver volume and free hemoglobin load on renal dysfunction. Intraoperative blood salvage was conducted in standard fashion, and in each case a sample of the blood was removed for testing. Outcome data on individual patients were collected during a 6-year period (1992–1998). The total amount of free hemoglobin each patient received was calculated. Renal dysfunction was defined as a rise in creatinine level of 1.0 mg/dL above baseline. There were a total of 125 patients who received salvaged blood. The free hemoglobin concentration ranged from 19 to 304 mg/dL (mean, 87.5 mg/dL). Patients were stratified into groups on the basis of the total free hemoglobin received, and the Kruskal-Wallis test demonstrated a difference between groups in the prevalence of renal dysfunction ( P < 0.001). A total of 15 patients (12%) had significant postoperative renal dysfunction. There was an association between the amount of free hemoglobin load and subsequent renal dysfunction. This may warrant further study toward establishing policies and limits regarding maximal free hemoglobin blood.

Does cell-saver blood administration and free hemoglobin load cause renal dysfunction?

Our aim was to evaluate the impact of cell-saver volume and free hemoglobin load on renal dysfunction. Intraoperative blood salvage was conducted in standard fashion, and in each case a sample of the blood was removed for testing. Outcome data on individual patients were collected during a 6-year period (1992-1998). The total amount of free hemoglobin each patient received was calculated. Renal dysfunction was defined as a rise in creatinine level of 1.0 mg/dL above baseline. There were a total of 125 patients who received salvaged blood. The free hemoglobin concentration ranged from 19 to 304 mg/dL (mean, 87.5 mg/dL). Patients were stratified into groups on the basis of the total free hemoglobin received, and the Kruskal-Wallis test demonstrated a difference between groups in the prevalence of renal dysfunction (P < 0.001). A total of 15 patients (12%) had significant postoperative renal dysfunction. There was an association between the amount of free hemoglobin load and subsequent renal dysfunction. This may warrant further study toward establishing policies and limits regarding maximal free hemoglobin blood.

Sustained infection induces 2 distinct microvascular mechanisms in the splanchnic circulation

BACKGROUND

Altered intestinal blood flow during systemic inflammation leads to organ dysfunction. Mucosal ischemia occurs during sepsis despite an increase in portal blood flow. We hypothesized that separate mechanisms are active in the large resistance and small mucosal microvessels to account for this dichotomy.

METHODS

Chronic infection was induced in rats by bacterial inoculation (Escherichia coli and Bacteroides fragilis) of an implanted subcutaneous sponge. Separate groups were studied at 24 and 72 hours after a single inoculation of bacterium or 24 hours after a second inoculation (ie, 72 hours of sepsis). Time-matched controls were used for each group. Intravital microscopy of the terminal ileum was used to assess endothelial-dependent vasodilation to acetylcholine (10(-9) to 10(-5) mol/L) in resistance (A(1)) and premucosal (A(3)) arterioles. Threshold sensitivity (-log of 20% response dose) was calculated from dose response curves for each animal.

RESULTS

Vasodilator sensitivity to acetylcholine in A(1) arterioles was significantly decreased at 24 hours, and these changes persisted up to 72 hours after a single bacterial inoculation. There was no change in the dilator sensitivity of A(3) arterioles after a single inoculation. When there was a challenge with a second bacterial inoculation, there was a reversal of the A(1) dilator response and an increase in A(3) sensitivity.

CONCLUSIONS

An initial septic event results in a decrease in dilator reactivity in the resistance A1 arterioles that persists for at least 72 hours. A sustained septic challenge results in increased dilator reactivity in both A(1) and A(3) vessels. This enhanced sensitivity during sepsis suggests that more than 1 therapeutic approach to preservation of intestinal blood flow will be necessary.

Lazaroid and pentoxifylline suppress sepsis-induced increases in renal vascular resistance via altered arachidonic acid metabolism

Early sepsis leads to renal hypoperfusion, despite a hyperdynamic systemic circulation. It is thought that failure of local control of the renal microcirculation leads to hypoperfusion and organ dysfunction. Of the many mediators implicated in the pathogenesis of microvascular vasoconstriction, arachidonic acid metabolites are thought to be important. Vasoconstriction may be due to excess production of vasoconstrictors or loss of vasodilators. Using the isolated perfused kidney model, we describe a sepsis-induced rise in renal vascular resistance and increased production of key arachidonic acid metabolites, both vasoconstrictors and vasodilators, suggesting excessive production of vasoconstrictors as a cause for microcirculatory hypoperfusion. There is evidence of increased enzymatic production of arachidonic acid metabolites as well as nonenzymatic, free radical, catalyzed conversion of arachidonic acid. Pentoxifylline (a phosphodiesterase inhibitor) and U74389G (an antioxidant) both have a protective effect on the renal microcirculation during sepsis. Both drugs appear to alter the renal microvascular response to sepsis by altering renal arachidonic acid metabolism. This study demonstrates that sepsis leads to increased renal vascular resistance. This response is in part mediated by metabolites produced by metabolism of arachidonic acid within the kidney. The ability of drugs to modulate arachidonic acid metabolism and so alter the renal response to sepsis suggests a possible role for these agents in protecting the renal microcirculation during sepsis.

Evolution in the management of hepatic trauma: a 25-year perspective

OBJECTIVE

To define the changes in demographics of liver injury during the past 25 years and to document the impact of treatment changes on death rates.

SUMMARY BACKGROUND DATA

No study has presented a long-term review of a large series of hepatic injuries, documenting the effect of treatment changes on outcome. A 25-year review from a concurrently collected database of liver injuries documented changes in treatment and outcome.

METHODS

A database of hepatic injuries from 1975 to 1999 was studied for changes in demographics, treatment patterns, and outcome. Factors potentially responsible for outcome differences were examined.

RESULTS

A total of 1,842 liver injuries were treated. Blunt injuries have dramatically increased; the proportion of major injuries is approximately 16% annually. Nonsurgical therapy is now used in more than 80% of blunt injuries. The death rates from both blunt and penetrating trauma have improved significantly through each successive decade of the study. The improved death rates are due to decreased death from hemorrhage. Factors responsible include fewer major venous injuries requiring surgery, improved outcome with vein injuries, better results with packing, and effective arterial hemorrhage control with arteriographic embolization.

CONCLUSIONS

The treatment and outcome of liver injuries have changed dramatically in 25 years. Multiple modes of therapy are available for hemorrhage control, which has improved outcome.

Prehospital hypotension as a valid indicator of trauma team activation

BACKGROUND

Criteria for trauma team activation are continually being evaluated to ensure proper utilization of resources. We examined the impact of prehospital (PH) hypotension (systolic blood pressure < or = 90) on outcome (operative intervention and mortality) and its usefulness as an indicator for trauma team activation.

METHODS

A database was created by using the trauma registry for all nonburned, injured patients from July of 1993 through October of 1998 at our Level I trauma center.

RESULTS

Of 6,976 patients (83% blunt injury) in the database, 4,437 had a PH blood pressure recorded. Documented PH hypotension was present in 791 patients. Hypotension persisted in the emergency department (ED) in 299 patients, but 193 of them showed minimal or no signs of life on arrival. Four hundred ninety-two patients had PH hypotension but normal ED systolic blood pressure, and 130 patients developed ED hypotension after normal PH systolic blood pressure. Nearly half of the patients with hypotension were taken from the ED directly to the operating room primarily for hemorrhage control procedures. The early and late mortality rates of patients with PH and ED hypotension were 12% and 32%, respectively. Other PH interventions had minimal effect on mortality in the hypotensive patient.

CONCLUSION

Prehospital hypotension remains a valid indicator for trauma team activation. Even though most of the non-DOA patients (492 of 598) were stable on arrival to the ED, nearly 50% required operative intervention, and an additional 25% required intensive care unit admission. The trauma team should be activated and involved with these patients early.