Insurance type is a determinant of 2-year mortality after non-neurologic trauma

BACKGROUND

Lack of health insurance (NO-INS) is associated with increased long-term mortality after head and spinal cord injuries (NEURO-TRA). Less is known about the influence of insurance type and long-term mortality following non-NEURO-TRA. We hypothesized that NO-INS would be associated with 2-y mortality after moderate to severe injury.

METHODS

Adults (>or=18) treated at a level-I trauma center following a moderate to severe blunt injury (ISS>15) and without NEURO-TRA from 2000-2005 and discharged alive were eligible for the study. Two-y mortality was determined utilizing the Social Security Administration Death Master File. Logistic regression analysis was used to determine if type of insurance [NO-INS, Private (PRIV-INS), Medicare/Medicaid; GOV-INS), or Other (OTH-INS)] was related to 2-y mortality.

RESULTS

One thousand nine hundred fifty-eight patients met study inclusion/exclusion criteria. Two-y risk of death was 2.96%. On univariate analysis, admission age, lactate, and insurance type were associated with 2-y mortality (P<0.25). However, race was not. After adjusting for admission age and lactate, compared with PRIV-INS, having either NO-INS or GOV-INS was significantly associated with increased 2-y mortality. The analysis was repeated without patients eligible for Medicare (Age>or=65), and GOV-INS was still associated with increased 2-y mortality (OR 4.47 P<0.05).

CONCLUSION

Following moderate to severe blunt, non-NEURO-TRA, having GOVT-INS or NO-INS was associated with increased 2-y mortality. The mechanism by which this association may be explained is unclear. Future research focused on elucidating mechanisms behind poor long-term outcomes should include an examination of socioeconomic status as a potential contributor to reduced long-term mortality after injury.

The "July phenomenon": is trauma the exception?

BACKGROUND

The concept of increased medical errors in July, secondary to new residents (the "July phenomenon"), often receives considerable attention without supporting evidence. A recent study reported a 41% increase in mortality during July and August in general surgery patients. The objective of this study was to determine if a July phenomenon existed in a Level I trauma center with an attending present at all times.

STUDY DESIGN

A retrospective cohort study was conducted at an academic, tertiary Level I trauma center. Blunt trauma patients admitted during a 5-year period were compared for differences in outcomes by month and quarter. Chi-square and analysis of variance were used for categorical and continuous variables where appropriate. Linear regression was used to examine the effect of month on ventilator support days, ICU days, and minutes in the resuscitation room. Multivariable linear regression was used to examine the effect of month and quarter on mortality.

RESULTS

A total of 12,525 patients were analyzed by month and 14,798 patients were analyzed by quarter. Overall, 68% were men and 32% women, with a mean age of 39.5 years. Mean Injury Severity Score was 12.4. Mean 24-hour transfusion requirement was 0.5 U. Mean emergency department Glasgow Coma Scale score was 14. Multivariable logistic regression failed to show month or quarter of the year to be an independent predictor of mortality after adjusting for age, Injury Severity Score, emergency department Glasgow Coma Scale score, and 24-hour transfusion requirement (c = 0.97). Linear regression failed to show any monthly variation on ventilator-support days, ICU days, or minutes in the resuscitation room.

CONCLUSIONS

The July phenomenon does not exist at this Level I trauma center with in-hospital attending supervision.

Prosthetic Vascular Conduit in Contaminated Fields: A New Technology to Decrease ePTFE Infections

Vascular reconstruction using prosthetic materials in contaminated fields can lead to infection, graft loss, and subsequent amputation. We hypothesized that minocycline and rifampin bound to an ePTFE graft using a unique methacrylate technology would provide for resistance from infection and controlled antibiotic elution. Kirby Bauer susceptibility testing was performed on plates overlaid with Staph aureus (SA) and Staph epidermidis (SE) using 6 mm diameter discs of uncoated graft or antibiotic coated graft (ABX). Zones of inhibition (ZIH) were determined after 24 hours. ABX grafts were then placed in a continuous water bath and a recirculating, pulsatile flow device. Susceptibility testing and high performance liquid chromatography with mass spectroscopy was performed to determine graft performance and antibiotic elution rate. ABX grafts had an average ZIH of 35 mm for SA and 44 mm for SE (each P < 0.0001). After the 1 week water bath, the ZIH of the ABX grafts was 23 mm on both the SA and SE plates. The high performance liquid chromatography with mass spectroscopy revealed that after 24 hours, 50 per cent of the antibiotics remained on the graft, and there was a sustained elution for 7 days. Minocycline and rifampin can be bound to ePTFE vascular grafts using a unique methacrylate method. In vitro, the grafts provide a slow elution of antibiotics that provide resistance from infection by SA and SE for up to 2 weeks after graft insertion.

Reduction in Inadequate Empiric Antibiotic Therapy for Ventilator-Associated Pneumonia: Impact of a Unit-Specific Treatment Pathway

Empiric antibiotic therapy is routinely initiated for patients with presumed ventilator-associated pneumonia (VAP). Reported mortality rates for inadequate empiric antibiotic therapy (IEAT) for VAP range from 45 to 91 per cent. The purpose of this study was to determine the effect of a unit-specific pathway for the empiric management of VAP on reducing IEAT episodes and improving outcomes in trauma patients. Patients admitted with VAP over 36-months were identified and stratified by gender, age, severity of shock, and injury severity. Outcomes included number of IEAT episodes, ventilator days, intensive care unit days, hospital days, and mortality. Three hundred and ninety-three patients with 668 VAP episodes were identified. There were 144 (22%) IEAT episodes: significantly reduced compared with our previous study (39%) ( P < 0.001). Patients were classified by number of IEAT episodes: 0 (n = 271), 1 (n = 98) and ≥ 2 (n = 24). Mortality was 12 per cent, 13 per cent, and 38 per cent ( P < 0.001), respectively. Multivariable logistic regression identified multiple IEAT episodes as an independent predictor of mortality (odds ratio = 4.7; 95% confidence interval: 1.684–13.162). Multiple IEAT episodes were also associated with prolonged mechanical ventilation and intensive care unit stay ( P < 0.001). Trauma patients with multiple IEAT episodes for VAP have increased morbidity and mortality. Adherence to a unit-specific pathway for the empiric management of VAP reduces multiple IEAT episodes. By limiting IEAT episodes, resource utilization and hospital mortality are significantly decreased.

Prosthetic vascular conduit in contaminated fields: a new technology to decrease ePTFE infections

Vascular reconstruction using prosthetic materials in contaminated fields can lead to infection, graft loss, and subsequent amputation. We hypothesized that minocycline and rifampin bound to an ePTFE graft using a unique methacrylate technology would provide for resistance from infection and controlled antibiotic elution. Kirby Bauer susceptibility testing was performed on plates overlaid with Staph aureus (SA) and Staph epidermidis (SE) using 6 mm diameter discs of uncoated graft or antibiotic coated graft (ABX). Zones of inhibition (ZIH) were determined after 24 hours. ABX grafts were then placed in a continuous water bath and a recirculating, pulsatile flow device. Susceptibility testing and high performance liquid chromatography with mass spectroscopy was performed to determine graft performance and antibiotic elution rate. ABX grafts had an average ZIH of 35 mm for SA and 44 mm for SE (each P < 0.0001). After the 1 week water bath, the ZIH of the ABX grafts was 23 mm on both the SA and SE plates. The high performance liquid chromatography with mass spectroscopy revealed that after 24 hours, 50 per cent of the antibiotics remained on the graft, and there was a sustained elution for 7 days. Minocycline and rifampin can be bound to ePTFE vascular grafts using a unique methacrylate method. In vitro, the grafts provide a slow elution of antibiotics that provide resistance from infection by SA and SE for up to 2 weeks after graft insertion.

Reduction in inadequate empiric antibiotic therapy for ventilator-associated pneumonia: impact of a unit-specific treatment pathway

Empiric antibiotic therapy is routinely initiated for patients with presumed ventilator-associated pneumonia (VAP). Reported mortality rates for inadequate empiric antibiotic therapy (IEAT) for VAP range from 45 to 91 per cent. The purpose of this study was to determine the effect of a unit-specific pathway for the empiric management of VAP on reducing IEAT episodes and improving outcomes in trauma patients. Patients admitted with VAP over 36-months were identified and stratified by gender, age, severity of shock, and injury severity. Outcomes included number of IEAT episodes, ventilator days, intensive care unit days, hospital days, and mortality. Three hundred and ninety-three patients with 668 VAP episodes were identified. There were 144 (22%) IEAT episodes: significantly reduced compared with our previous study (39%) (P < 0.001). Patients were classified by number of IEAT episodes: 0 (n = 271), 1 (n = 98) and > or = 2 (n = 24). Mortality was 12 per cent, 13 per cent, and 38 per cent (P < 0.001), respectively. Multivariable logistic regression identified multiple IEAT episodes as an independent predictor of mortality (odds ratio = 4.7; 95% confidence interval: 1.684-13.162). Multiple IEAT episodes were also associated with prolonged mechanical ventilation and intensive care unit stay (P < 0.001). Trauma patients with multiple IEAT episodes for VAP have increased morbidity and mortality. Adherence to a unit-specific pathway for the empiric management of VAP reduces multiple IEAT episodes. By limiting IEAT episodes, resource utilization and hospital mortality are significantly decreased.

Diagnostic laparoscopy for the evaluation of occult diaphragmatic injury following penetrating thoracoabdominal trauma

BACKGROUND

Occult diaphragmatic injury following penetrating thoracoabdominal trauma can be difficult to diagnose. Radiographic findings are often non-specific or absent. Undetected injuries may remain clinically silent, only to present later with life-threatening complications associated with diaphragmatic herniation. Diagnostic laparoscopy allows for the evaluation of trauma patients lacking clinical indications for a formal laparotomy. The purpose of this study was to evaluate the incidence of occult diaphragmatic injury and investigate the role of laparoscopy in patients with penetrating thoracoabdominal trauma who lack indications for exploratory laparotomy except the potential for a diaphragmatic injury.

METHODS

Haemodynamically stable patients with penetrating thoracoabdominal trauma without indications for laparotomy (haemodynamic instability, evisceration, or peritonitis on exam) and evaluated with diagnostic laparoscopy to determine the presence of a diaphragmatic injury were retrospectively reviewed. Thoracoabdominal wounds were defined as wounds bounded by the nipple line over the anterior and posterior chest superiorly and the costal margin inferiorly.

RESULTS

One hundred and eight patients were evaluated for penetrating thoracoabdominal injuries (80 stabs and 28 gunshots) over the study period. 22 (20%) diaphragmatic injuries were identified. These were associated with injuries to the spleen (5), stomach (3) and liver (2). There was a greater incidence of haemopneumothorax (HPTX) in patients with diaphragmatic injury (32%) compared to those without injury (20%). 29% of patients with a HPTX had a diaphragmatic injury. However, 18% of patients with a normal chest radiograph were also found to have a diaphragmatic injury.

CONCLUSIONS

The incidence of diaphragmatic injury associated with penetrating thoracoabdominal trauma is high. Clinical and radiographic findings can be unreliable for detecting occult diaphragmatic injury. Diagnostic laparoscopy provides a vital tool for detecting occult diaphragmatic injury among patients who have no other indications for formal laparotomy.

Impact of gender on outcomes after blunt injury: a definitive analysis of more than 36,000 trauma patients

BACKGROUND

The concept that premenopausal female patients are more resistant to shock than male patients has been shown in numerous preclinical models. The more relevant effect of gender on clinically important outcomes after trauma is less clear. Clinical studies have been conflicting, both supporting and refuting the protective effects of gender on outcomes, primarily because of limitations in sample size and patient stratification. In an attempt to resolve this ongoing dispute, we evaluated the effect of gender on various outcomes in the largest single institutional series of trauma patients reported in the literature after blunt injury.

STUDY DESIGN

All patients sustaining blunt trauma during a 10-year period were identified from the trauma registry and stratified by gender, age, and severity of shock and injury. Outcomes included ventilator-associated pneumonia, ARDS, bacteremia, ventilator days, ICU days, hospital length of stay, and mortality. Multivariable logistic regression was performed to determine whether gender was an independent predictor of mortality, morbidity, or both.

RESULTS

There were 36,010 patients identified; 304 died in the resuscitation area, leaving 24,331 men and 11,375 women for analysis. Logistic regression identified gender as an independent predictor of morbidity but failed to show gender as an independent predictor of early (48-hour and 7-day) and overall mortality.

CONCLUSIONS

Multivariable logistic regression analysis of a large trauma cohort definitively establishes that gender is not independently associated with mortality after blunt trauma in humans. In contrast, male gender was shown to be associated with increased morbidity. Unlike rodent studies, gender alone offers no survival advantage in humans after blunt trauma.

Descending necrotizing mediastinitis: unique complication of central venous catheterization

BACKGROUND

Central venous catheter placement is a common procedure in the intensive care unit. However, these devices are not without complications. We describe the first reported case of descending necrotizing mediastinitis secondary to central venous catheterization without evidence of associated vascular perforation.

METHODS

Case report and literature review.

RESULTS

A 24-year-old man developed descending necrotizing mediastinitis after exploratory laparotomy for a gunshot wound. A central venous catheter was presumed to be the source because blood, intraoperative, and catheter tip cultures grew the same Klebsiella organism, and there was no evidence of venous perforation at the initial operation.

CONCLUSIONS

Prompt recognition, adequate operative drainage, and appropriate antibiotics remain the best treatment for descending necrotizing mediastinitis.

Emergent pelvic fixation in patients with exsanguinating pelvic fractures

BACKGROUND

An alternative to embolization or external pelvic fixation (EPF) in patients with multiple pelvic fractures and hemorrhage is a pelvic orthotic device (POD), which may easily be placed in the resuscitation area. Little published information is available about its effectiveness. This study evaluated the efficacy of the POD compared with EPF in patients with life-threatening pelvic fractures.

STUDY DESIGN

We evaluated patients with blunt pelvic fractures over a 10-year period. Inclusion required multiple pelvic fractures with vascular disruption and severe retroperitoneal hematoma, open book fracture with symphysis diastasis, or sacroiliac disruption with vertical shear. Patients with EPF were compared with those in whom a POD was used. Outcomes included transfusions, hospital stay, and mortality.

RESULTS

There were 3,359 patients with pelvic fractures who were admitted: 186 (6%) met entry criteria; 93 had EPF and 93 had POD. There were no differences in age or shock severity. Both 24-hour (4.9 versus 17.1 U, p < 0.0001) and 48-hour transfusions (6.0 versus 18.6 U, p < 0.0001) were reduced with POD. Twenty-three percent of each group underwent pelvic angiography, and 24-hour transfusion amounts for those patients were also reduced with POD (9.9 versus 21.5 U, p < 0.007). Hospital length of stay (16.5 versus 24.4 days, p < 0.03) was less with POD. Although there was decreased mortality with POD (26%) versus EPF (37%), it was not statistically significant (p=0.11).

CONCLUSIONS

The therapeutic shift to POD has substantially reduced transfusion requirements and length of hospital stay, and has reduced mortality in patients with unstable pelvic fractures. POD has made a major contribution to the care of critically injured patients with the most severe pelvic fractures.

Initial chest CT obviates the need for repeat chest radiograph after penetrating thoracic trauma

The use of serial chest radiographs (CXRs) to evaluate patients with penetrating thoracic trauma is common practice. However, the time interval between these studies and the duration of observation remains uncertain. The purpose of this study was to evaluate whether a noncontrast chest CT is as reliable as a 6-hour CXR for detecting delayed pneumothorax (PTX) after penetrating thoracic trauma. Hemodynamically stable patients with isolated penetrating thoracic trauma were prospectively evaluated with a CXR and a noncontrast chest CT. If there was no PTX or hemothorax, or a finding that did not require immediate intervention, a 6-hour CXR was obtained. Findings were treated as clinically indicated and patients were discharged if all three studies were negative. One hundred eighteen patients were evaluated (89 stab wounds and 29 gunshot wounds). All initial CXRs were negative. CT identified six PTXs and one hemothorax. Two patients required operative intervention. There were no delayed findings on CXR provided the CT was negative. The mean time to CT and before disposition was 19 minutes and 8 hours, respectively, with a potential decrease in charges of $313.32 per patient. The use of serial CXRs provided no additional information that was not available on the initial chest CT, allowing for expedited discharge, decompressing overcrowded emergency areas, and reducing the number of patients leaving before completion of their work-up.

Initial Chest CT Obviates the Need for Repeat Chest Radiograph after Penetrating Thoracic Trauma

The use of serial chest radiographs (CXRs) to evaluate patients with penetrating thoracic trauma is common practice. However, the time interval between these studies and the duration of observation remains uncertain. The purpose of this study was to evaluate whether a noncontrast chest CT is as reliable as a 6-hour CXR for detecting delayed pneumothorax (PTX) after penetrating thoracic trauma. Hemodynamically stable patients with isolated penetrating thoracic trauma were prospectively evaluated with a CXR and a noncontrast chest CT. If there was no PTX or hemothorax, or a finding that did not require immediate intervention, a 6-hour CXR was obtained. Findings were treated as clinically indicated and patients were discharged if all three studies were negative. One hundred eighteen patients were evaluated (89 stab wounds and 29 gunshot wounds). All initial CXRs were negative. CT identified six PTXs and one hemothorax. Two patients required operative intervention. There were no delayed findings on CXR provided the CT was negative. The mean time to CT and before disposition was 19 minutes and 8 hours, respectively, with a potential decrease in charges of $313.32 per patient. The use of serial CXRs provided no additional information that was not available on the initial chest CT, allowing for expedited discharge, decompressing overcrowded emergency areas, and reducing the number of patients leaving before completion of their work-up.

The Utility of Serial Computed Tomography Imaging of Blunt Splenic Injury: Still Worth a Second Look?

BACKGROUND

Serial computed tomography (CT) imaging of blunt splenic injury (BSI) can identify the latent formation of splenic artery pseudoaneurysms (PSAs), contributing to improved success in splenic salvage. The practice of serial CT imaging, however, has not been embraced. The purpose of this study was to reevaluate the clinical practice of serial CT imaging within the context of an institutional protocol for the nonoperative management (NOM) of BSI.

METHOD

Consecutive patients with BSI selected for NOM were identified from our trauma registry. Patients were managed according to protocol, whereby hemodynamically stable patients with PSA on initial or follow-up CT imaging were referred for angiography. Follow-up CT was performed 24 to 48 hours after the initial CT. Data were abstracted from hospital, clinic, and radiology records, and included age, Injury Severity Score, splenic injury grade (SIG), and CT findings. The incidence and timing of PSA identification with respect to subsequent management and outcome were reviewed.

RESULTS

Of 426 BSI admissions during a 2.5-year period, 341 (80%) were selected for NOM. Mean follow-up was 39 days, with 76% followed for >or=7 days. Serial CT imaging resulted in the angiographic detection of 14 (4%) early PSAs and 11 (3%) latent PSAs. PSAs were associated with increasing SIG (p<0.001); however, 24% of PSAs were observed in SIG 1 and 2. Embolization was successful in 13 of 14 (93%) patients with early PSAs and 10 of 11 (91%) with latent PSAs. The splenic salvage rate for all patients selected for NOM during the study period was 329 of 341 (97%).

CONCLUSIONS

Adherence to a NOM protocol guided by serial CT imaging has resulted in one of the highest splenic salvage rates reported to date. Identification and embolization of latent PSA likely contributes to NOM success, given the unfavorable natural history of these lesions. Although PSA formation is correlated with increasing SIG, PSAs are not exclusive to higher-grade injury, warranting serial CT surveillance regardless of SIG.

Relationship between disruption of the unstirred mucus layer and intestinal restitution in loss of gut barrier function after trauma hemorrhagic shock

BACKGROUND

The factors involved in shock-induced loss of gut barrier function remain to be defined fully and studies investigating gut injury have focused primarily on the systemic side of the intestine.

METHODS

Male Sprague-Dawley rats were subjected to a laparotomy (trauma) and 90 minutes of trauma sham shock (T/SS) or actual trauma (laparotomy) hemorrhagic shock (T/HS) (30 mm Hg). At 0, 30, 60, or 180 minutes after the end of shock and volume resuscitation (reperfusion), the animals were killed and samples of the ileum were collected for intestinal morphologic analysis, analysis of the unstirred mucus layer, and for barrier function by measuring permeability to flourescein dextran.

RESULTS

T/HS-induced morphologic evidence of mucosal injury as well as epithelial apoptosis was present at the end of the shock period and maximal after 60 minutes of reperfusion. At 3 hours after reperfusion, the degree of villous injury and enterocyte apoptosis had decreased. In contrast to the morphologic appearance of the villi, disruption of the mucus layer became progressively more severe over time and was manifest as a decrease in mucus thickness, progressive loss of coverage of the luminal surface by the mucus layer, and a change in mucus appearance from a dense to a loose structure. Studies of intestinal permeability documented that T/HS-induced loss of gut barrier function persisted throughout the 3-hour reperfusion period and were associated with injury to the mucus layer as well as the villi.

CONCLUSIONS

T/HS leads to changes in the intestinal mucus layer as well as increased villous injury, apoptosis, and gut permeability. Additionally, increased gut permeability was associated with loss of the intestinal mucus layer suggesting that T/HS-induced injury to the mucus layer may contribute to the loss of gut barrier function.

"Awake" laparoscopy for the evaluation of equivocal penetrating abdominal wounds

BACKGROUND

Diagnostic laparoscopy is useful for the assessment of equivocal penetrating abdominal wounds, and has become the modality of choice for the evaluation of such wounds at our institution. We hypothesised that, in appropriate patients, diagnostic "awake" laparoscopy (AL) could be performed under local anaesthesia in the emergency department (ED), allowing for expedited discharge and potential cost savings.

METHODS

Selected haemodynamically stable patients with penetrating abdominal injury underwent AL. Suitability for AL was at the discretion of the attending surgeon. Identification of peritoneal penetration by AL led to exploratory laparotomy in the operating room. Patients with no evidence of peritoneal penetration were discharged from the ED (ALneg). These patients were matched to a cohort of 24 patients who underwent diagnostic laparoscopy in the OR which was negative for peritoneal penetration (DLneg). Length of stay and hospital charges were compared.

RESULTS

Over a 30-month period, 15 patients underwent AL without complication. No peritoneal penetration was found in 11 patients. The remaining four patients underwent exploratory laparotomy, of which two were positive for intra-abdominal injury. Mean time to discharge was 7h in the ALneg group versus 18 h in the DLneg group (p=0.0003). Cost savings on hospital charges averaged 2227 US dollars per patient in the ALneg group compared with the DLneg group.

CONCLUSIONS

AL may be safely performed in the ED, allowing for expedited patient discharge. Cost savings are achieved by the avoidance of charges inherent to diagnostic laparoscopy performed in the operating room.

Penetrating rectal trauma: management by anatomic distinction improves outcome

BACKGROUND

Controversy persists regarding the optimal management of penetrating rectal injuries, specifically with respect to the routine application of diversion and presacral drainage. Our previous experience suggested that management decisions based on precise anatomic characterization of injury relative to retroperitoneal involvement might improve outcome. A clinical pathway was developed and implemented. Patients managed by the pathway (PATH) were compared with the previous study (PREV, n=58) to determine the impact of the clinical pathway on outcome.

METHODS

Consecutive patients with full-thickness penetrating rectal injury subsequent to the development of the pathway were evaluated. Intraperitoneal rectal injuries (IP) were treated with primary repair. Injuries to the proximal two-thirds and accessible distal one-third of the extraperitoneal rectum (EP) were treated with repair and selective fecal diversion. Inaccessible distal EP injuries were treated with diversion and presacral drainage. Infectious complications (wound infection, bacteremia, intraabdominal abscess, retroperitoneal abscess) were compared between the PATH and PREV groups.

RESULTS

In all, 54 patients were identified. Demographics, injury severity, and preventive antibiotics (24-hour) were similar between groups. Overall infectious complication rate was 13% in the PATH group versus 31% in the PREV group (p<0.05). There was a zero incidence of retrorectal abscess in the PATH group versus 11% of the total complications in the PREV group.

CONCLUSIONS

Implementation of the pathway resulted in a significant decrease in infectious morbidity. Management by anatomic distinction allows for omission of colostomy in most IP injuries and select EP injuries, while diminishing the risk of retrorectal abscess in EP injuries with the judicious application of presacral drainage.

The futility of the clinical pulmonary infection score in trauma patients

INTRODUCTION

The Clinical Pulmonary Infection Score (CPIS) has received much attention recently. Advocates have touted its use for the diagnosis and duration of therapy in patients with ventilator-associated pneumonia (VAP). However, little has been written about its utility in trauma patients. The clinical, physiologic, and radiologic components of the CPIS may be difficult to differentiate from the systemic effects of injury. Quantitative cultures of the lower airway have been shown to be efficacious in differentiating VAP from the systemic inflammatory response syndrome (SIRS). In this study, we evaluated the potential use of CPIS as the sole means for diagnosis of VAP in critically injured patients.

METHODS

Patients were identified from the VAP database maintained in our Level I trauma center. Only those who had CPIS calculated at the time of bronchoscopy with BAL were included. VAP required >or=10 colonies/mL on quantitative BAL for diagnosis. Antibiotic therapy was based on quantitative BAL results. Patients with <10 colonies/mL were diagnosed with SIRS. Sensitivity and specificity of a CPIS>6 for VAP diagnosis (confirmed by BAL) were calculated.

RESULTS

In all, 158 patients underwent 285 BALs. The overall incidence for VAP was 42%. Patients with episodes of VAP and SIRS were well matched for age, Injury Severity Score, APACHE II score, and Glasgow Coma Scale score. The average CPIS was 6.8 in patients with SIRS and 6.9 for those with VAP. Using a CPIS>6 as the threshold for VAP only yielded a sensitivity of 61% and a specificity of 43%.

CONCLUSIONS

CPIS cannot differentiate VAP from SIRS in critically injured patients. Using CPIS to initiate antibiotic therapy in trauma patients could be harmful. Whether CPIS is useful to determine duration of antibiotic therapy is unknown.

Burns, bacterial translocation, gut barrier function, and failure

The development of systemic inflammation, acute lung injury, and multiple organ failure after a major thermal injury, as well as nonthermal forms of trauma, remain relatively common causes of morbidity and mortality. During the past two decades, increasing recognition that the ischemic gut may contribute to the development of sepsis and organ failure in burn patients, as well as other critically ill patient populations, has led to new hypotheses to explain burn-induced multiple organ failure as well as highlighted the importance of early enteral nutrition. Thus, the goal of this review will be to provide a perspective on the evolution of the gut hypothesis of systemic inflammation and distant organ dysfunction.

Is ventilator-associated pneumonia in trauma patients an epiphenomenon or a cause of death?

BACKGROUND

Ventilator-associated pneumonia (VAP) is a common infection among patients in trauma intensive care units (ICUs). It has been suggested by different investigators that VAP is an indicator of injury severity and not necessarily associated with mortality. Crude mortality rates approximating 20% have been reported for trauma patients with VAP. Most studies have involved the most severely injured patients, making it difficult to determine the relative contribution of either VAP or injury severity to death. If VAP is independently associated with mortality, this relationship should be most evident in less severely injured patients. We studied patients with less severe injuries (Injury Severity Score, ISS < 25) to determine the impact of VAP on outcomes.

METHODS

Patients admitted to the trauma ICU with ISS < 25 were identified from the trauma registry of a level I trauma center. Patients with penetrating injuries and those who died within 48 h of injury were excluded. Pneumonia was diagnosed using quantitative cultures of bronchoalveolar lavage effluent (>/= 10(5) colony forming units/mL). Risk factors for VAP, including age, transfusions with 24 h of admission, brain injury, and chest injury severity were analyzed. Logistic regression analysis was then performed to determine independent factors for death.Results: There were 15,492 blunt admissions over a 5.5 year study period who survived >48 h. Of these, 5,860 (38%) were admitted to the ICU, and 4,111 (70% of ICU admissions) had ISS < 25. The incidence of VAP in this group was 8%. Patients with VAP were older (47 vs 39 years), had more transfusions within 24 h (2.5 vs 0.9 units of red blood cell concentrates) and had greater injury severity by ISS (16.7 vs 12.6 points), GCS (Glasgow Coma Scale) score (11.8 vs. 13.7 points) and chest AIS (Abbreviated Injury Scale) (1.7 vs 0.9 points; all p < 0.001). Overall mortality was 4%. Mortality was 16% in patients with VAP compared to 3% in those without VAP (p < 0.0001). Logistic regression analysis identified transfusions, age, and VAP as independent predictors of mortality. Other descriptors of injury severity (ISS, GCS, or chest AIS) were not associated with death.

RESULTS

There were 15,492 blunt admissions over a 5.5 year study period who survived . 48 h. Of these, 5,860 (38%) were admitted to the ICU, and 4,111 (70% of ICU admissions) had ISS , 25. The incidence of VAP in this group was 8%. Patients with VAP were older (47 vs 39 years), had more transfusions within 24 h (2.5 vs 0.9 units of red blood cell concentrates) and had greater injury severity by ISS (16.7 vs 12.6 points), GCS (Glasgow Coma Scale) score (11.8 vs. 13.7 points) and chest AIS (Abbreviated Injury Scale) (1.7 vs 0.9 points; all p , 0.001). Overall mortality was 4%. Mortality was 16% in patients with VAP compared to 3% in those without VAP (p , 0.0001). Logistic regression analysis identified transfusions, age, and VAP as independent predictors of mortality. Other descriptors of injury severity (ISS, GCS, or chest AIS) were not associated with death.

CONCLUSIONS

Ventilator-associated pneumonia is independently associated with death in less severely injured trauma patients. This demonstrates the need for effective diagnostic techniques so that adequate therapy may be initiated. Prevention of VAP in less severely injured trauma patients should increase survival.

Pancreatic duct ligation reduces lung injury following trauma and hemorrhagic shock

OBJECTIVE

To determine whether pancreatic digestive enzymes released into the ischemic gut during an episode of T/HS are involved in the generation of distant organ injury. This hypothesis was tested by examining the effect of PDL on T/HS-induced intestinal injury, lung injury, and RBC deformability.

SUMMARY BACKGROUND DATA

The effect of pancreatic duct ligation (PDL) on distant organ injury following trauma/hemorrhagic shock (T/HS) was examined. PDL before T/HS decreases lung and red blood cell (RBC) injury and exerts a limited protective effect on the gut. Pancreatic proteases in the ischemic gut appear to be involved in gut-induced lung and RBC injury. Based on recent work, it appears that proinflammatory and/or toxic factors, which are generated by the ischemic intestine, play an important role in the pathogenesis of multiple organ failure. The process by which these toxic factors are generated remains unknown. Previous experimental work has clearly documented that intraluminal inhibition of pancreatic proteases decreases the degree of T/HS-induced lung injury and neutrophil activation. One possible explanation for this observation is that the toxic factors present in intestinal lymph are byproducts of interactions between pancreatic proteases and the ischemic gut.

METHODS

Male Sprague-Dawley rats were subjected to a laparotomy (trauma) and 90 minutes of sham (T/SS) or T/HS with or without PDL. At 3 and 24 hours following resuscitation, animals were killed and samples of gut, lung, and blood were collected for analysis. Lung permeability, pulmonary myeloperoxidase levels, and bronchoalveolar fluid protein content were used to quantitate lung injury. Intestinal injury was determined by histologic analysis of terminal ileum (% villi injured). To assess RBC injury, RBC deformability was measured, as the RBC elongation index (RBC-EI), using a LORCA device.

RESULTS

At 3 and 24 hours following resuscitation, PDL prevented shock-induced increases in lung permeability to both Evans blue dye and protein in addition to preventing an increase in pulmonary myeloperoxidase levels. T/HS-induced impairments in RBC deformability were significantly reduced at both time points in the PDL + T/HS group, but deformability did not return to T/SS levels. PDL did reduce the magnitude of ileal injury at 3 hours after T/HS, but the protective effect was lost at 24 hours after T/HS.

CONCLUSIONS

PDL prior to T/HS decreases lung injury and improves RBC deformability but exerts a limited protective effect on the gut. Thus, the presence of pancreatic digestive enzymes in the ischemic gut appears to be involved in gut-induced lung and RBC injury.

Angiographic Embolization for Liver Injuries: Low Mortality, High Morbidity

OBJECTIVE

Angiographic embolization (AE) is a safe and effective method for controlling hemorrhage in both blunt and penetrating liver injuries. Improved survival after hepatic injuries has been documented using a multimodality approach; however, patients still have significant long-term morbidity. This study examines further the role of AE in both blunt and penetrating liver injuries and the outcomes of its use.

METHODS

The medical records of 37 consecutive patients admitted from 1995 to 2002 to a Level I trauma center who underwent hepatic angiography with the intent to embolize were reviewed. Demographic and clinical information including Injury Severity Score, length of stay, mortality, intra-abdominal complications, admission physiologic variables, and the number and type of abdominal operations performed were collected.

RESULTS

Thirty-seven patients underwent hepatic angiography and 26 patients had hepatic embolization performed. Eleven patients underwent early-AE, immediately after computed tomographic scanning, and 15 underwent late-AE, after liver-related operations or later in their hospital course. There was a 27% mortality rate overall. There were 11 liver-related complications in the 26 embolizations. Excluding the early deaths, the associated morbidity was 58%, which included hepatic necrosis, hepatic abscesses, and bile leaks.

CONCLUSION

There is increasing adjunctive use of AE in patients managed both operatively and nonoperatively. Intra-abdominal complications are common in these salvaged patients with severe liver injuries. Those patients that underwent early-AE received significantly fewer blood transfusions and more commonly had sterile hepatic collections. Only 26% of patients required liver-related surgery after AE. Therefore, the integration of AE as an adjunctive modality for patients with high-grade liver injuries is a safe and effective therapeutic option.

Influence of gut microflora on mesenteric lymph cytokine production in rats with hemorrhagic shock

OBJECTIVE

The aim of the present study was to test the hypothesis that the resident gut microflora play a role in modulating gut cytokine production under normal circumstances and in response to tissue injury with or without hemorrhagic shock.

METHODS

The postnodal lymph was collected from the main mesenteric lymphatic channel 1 hour before, during (1.5 hours), and hourly for 6 hours after 90 minutes of sham or actual hemorrhagic shock (30 mm Hg) in the following three groups of rats, all of which had laparotomies and vascular instrumentation: rats with a normal gut flora (NF), rats whose gut flora had been decontaminated with oral antibiotics (AD), and rats with Escherichia coli C25 intestinal overgrowth (MA). Interleukin (IL)-6 and TNF levels in the mesenteric lymph were measured using cytokine-dependent cellular assays. Endotoxin levels and endotoxin-neutralizing capacity in the lymph were also measured.

RESULTS

Mesenteric lymph IL-6 levels in the laparotomized MA-sham animals were significantly elevated compared with NF-sham animals at 2 to 4 hours (p < 0.05) and at 5 and 6 hours after sham shock (p < 0.01). Similarly, IL-6 levels in laparotomized AD-shock animals were increased when compared with NF-shock animals 3 hours after shock (p < 0.001). Lymph tumor necrosis factor bioactivity, although present in all surgically manipulated groups, was scarcely detectable in untouched animals. Endotoxin-neutralizing capacity was significantly impaired in shocked animals compared with untouched animals.

CONCLUSION

Changes in the gut microflora modulate the gut cytokine production after tissue injury with or without hemorrhagic shock, with intestinal bacterial overgrowth leading to the greatest increase in mesenteric lymph IL-6 levels.

Improving outcomes following penetrating colon wounds: application of a clinical pathway

INTRODUCTION

During World War II, failure to treat penetrating colon injuries with diversion could result in court martial. Based on this wartime experience, colostomy for civilian colon wounds became the standard of care for the next 4 decades. Previous work from our institution demonstrated that primary repair was the optimal management for nondestructive colon wounds. Optimal management of destructive wounds requiring resection remains controversial. To address this issue, we performed a study that demonstrated risk factors (pre or intraoperative transfusion requirement of more than 6 units of packed red blood cells, significant comorbid diseases) that were associated with a suture line failure rate of 14%, and of whom 33% died. Based on these outcomes, a clinical pathway for management of destructive colon wounds was developed. The results of the implementation of this pathway are the focus of this report.

METHODS

Patients with penetrating colon injury were identified from the registry of a level I trauma center over a 5-year period. Records were reviewed for demographics, injury characteristics, and outcome. Patients with nondestructive injuries underwent primary repair. Patients with destructive wounds but no comorbidities or large transfusion requirement underwent resection and anastomosis, while patients with destructive wounds and significant medical illness or transfusion requirements of more than 6 units/blood received end colostomy. The current patients (CP) were compared to the previous study (PS) to determine the impact of the clinical pathway. Outcomes examined included colon related mortality and morbidity (suture line leak and abscess).

RESULTS

Over a 5.5-year period, 231 patients had penetrating colon wounds. 209 survived more 24 hours and comprise the study population. Primary repair was performed on 153 (73%) patients, and 56 patients had destructive injuries (27%). Of these, 40 (71%) had resection and anastomosis and 16 (29%) had diversion. More destructive injuries were managed in the CP group (27% vs. 19%). Abscess rate was lower in the CP group (27% vs. 37%), as was suture line leak rate (7% vs. 14%). Colon related mortality in the CP group was 5% as compared with 12% in the PS group.

CONCLUSIONS

The clinical pathway for destructive colon wound management has improved outcomes as measured by anastomotic leak rates and colon related mortality. The data demonstrated the need for colostomy in the face of shock and comorbidities. Institution of this pathway results in colostomy for only 7% of all colon wounds.

Hypoxia combined with Escherichia coli produces irreversible gut mucosal injury characterized by increased intestinal cytokine production and DNA degradation

The objective of the present study was to determine whether hypoxia/reoxygenation in the absence or presence of intestinal bacteria would affect the integrity of the gut mucosal epithelium (as evidenced by histologic changes) and increase the local production of cytokines (interleukin 6 [IL-6] and tumor necrosis factor [TNF]). Rat ileal mucosal membranes were harvested and their electrophysiologic properties and barrier function were measured ex vivo in the Ussing chamber system. Membranes were exposed to normoxia, normoxia + Escherichia coli, hypoxia for 40 min followed by normoxia, or hypoxia for 40 min + E. coli followed by normoxia for 3 h. IL-6 and TNF levels were measured using cytokine-dependent cellular assays. Morphological changes and the degree of DNA fragmentation were used as quantitative markers of gut mucosal injury. Mucosal integrity was maintained in the normoxia group. The addition of bacteria increased the IL-6 response and reduced mucosal integrity. During the hypoxic period, a transient decline in resistance (R) occurred and cytokine production was reduced. In the hypoxic ileal membranes not exposed to E coli, reoxygenation reversed the change in R and increased IL-6 production. The combination of hypoxia/reoxygenation plus E. coli bacterial challenge resulted in the greatest extent of gut mucosal injury and increase in TNF production. The results of this study support the hypothesis that the combination of increased intestinal bacterial levels superimposed on an ischemia/reperfusion injury increases the magnitude of gut mucosal injury and the production and subsequent release of proinflammatory cytokines.

Acute lung injury after hemorrhagic shock is dependent on gut injury and sex

Recent studies have established gut-derived lymph rather than portal blood as the major source of toxic mediators after hemorrhagic shock that causes distant organ injury. Similarly, emerging data have identified sex as a major modifier of the response to injury and illness. Thus we tested the hypothesis that female rats would be more resistant to shock-induced lung injury than male rats because females are more resistant to shock-induced gut injury and produce mesenteric lymph that is less toxic to endothelial cells. Male and female rats were subjected to sham or hemorrhagic shock and lung permeability was quantitated by Evans blue dye and protein extravasation into the alveolar space. Next, mesenteric lymph collected from shocked and sham-shocked rats of both sexes was incubated with human umbilical vein endothelial cells (HUVECs) and assayed for toxicity. Trypan blue dye exclusion and the release of lactate dehydrogenase assessed HUVEC viability and injury respectively. Lastly, sections of the terminal ileum were histologically examined for evidence of shock-induced mucosal injury. Male rats but not female rats subjected to hemorrhagic shock had evidence of increased lung permeability and produced mesenteric lymph that was cytotoxic to HUVECs. Shock caused gut injury in the male rats whereas histological evidence of gut injury was not observed in the female rats. Hemorrhagic shock-induced lung injury depends on gut injury and mesenteric lymph appears to be the route by which gut-derived toxic factors exit the gut to cause lung injury. The resistance of female rats to shock-induced lung injury appears to be secondary to their resistance to shock-induced gut injury.

Mesenteric lymph duct ligation provides long term protection against hemorrhagic shock-induced lung injury

Recently we have shown that ligation of the main mesenteric lymph (MLN) duct prior to an episode of hemorrhagic shock (HS) prevents shock-induced lung injury. Yet, ligation or diversion of intestinal lymph immediately prior to injury is not clinically feasible. Diversion of intestinally derived lymph after injury to protect against secondary insults is possible, but it is not known how long the protective effects of lymph ligation would last. Thus, we tested whether ligation of the MLN duct seven days prior to HS would still be protective. Male Sprague-Dawley rats were subjected to laparotomy with or without MLN duct ligation. Seven days later, half of the sham and actual MLN duct ligated animals randomly were selected to undergo HS (30 mmHG for 90 min). The other half of the animals was subjected to sham shock. Lung permeability, pulmonary myeloperoxidase (MPO) activity, and bronchoalveolar fluid (BALF) protein content were used to determine lung injury. Lymphatic division 7 days prior to HS continued to prevent shock induced lung injury as assessed by a lower Evans Blue dye concentration, BALF protein and MPO activity. In addition, there was no evidence of Patent Blue dye in the previously ligated MLN duct. Since ligation of the main mesenteric lymphatic duct continues to protect against shock-induced lung injury 1 week after duct ligation, it is feasible that lymphatic ligation performed after an injury remains protective against certain secondary insults for at least 1 week.

Gut-derived mesenteric lymph: a link between burn and lung injury

BACKGROUND

Previously, we showed that mesenteric lymph generated following hemorrhagic shock increases endothelial cell permeability and contributes to lung injury. It has also been shown that lymph produced at the site of burn injury plays a role in altering pulmonary vascular hemodynamics. In addition, previous experimental work has suggested that organs and tissues distant from the injury site may contribute to pulmonary dysfunction. One explanation would be that gut-derived inflammatory factors (in addition to those produced locally at the site of injury) are reaching the pulmonary circulation, where they exert their effects via the gut lymphatics.

HYPOTHESES

The 2 hypotheses herein were that (1) gut-derived factors carried in the mesenteric lymph of rats generated following thermal injury will contribute to lung injury and (2) intestinal bacterial overgrowth will potentiate the degree of burn-induced lung injury. These hypotheses were tested by examining the effect of mesenteric lymph flow interruption prior to thermal injury on burn-induced lung injury in rats with a normal intestinal bacterial flora and in rats with intestinal Escherichia coli overgrowth. These rats were termed E. coli-monoassociated rats.

METHODS

Normal intestinal bacterial flora and monoassociated male Sprague-Dawley rats were subjected to sham burn, 40% total body surface area burn, or lymphatic division plus burn. After 3 hours, 10 mg of Evans blue was injected to measure lung permeability. After the rats were killed, a bronchoalveolar lavage was performed and the fluid analyzed spectrophotometrically. Bronchoalveolar lavage fluid protein content, pulmonary myeloperoxidase activity, and alveolar apoptosis served to further quantitate lung injury.

RESULTS

Both normal intestinal bacterial flora and monoassociated-burned rats exhibited significant increases in lung permeability, bronchoalveolar lavage fluid protein content, myeloperoxidase activity, and alveolar apoptosis. The combination of monoassociation and thermal injury resulted in even further increases in lung injury over thermal injury alone. Lymphatic division prior to thermal injury ameliorated burn-induced increases in lung permeability, bronchoalveolar lavage fluid protein content, pulmonary myeloperoxidase accumulation, and alveolar apoptosis in both normal intestinal bacterial flora and monoassociated rats.

CONCLUSIONS

The results of this study support the hypothesis that gut-derived factors carried in the mesenteric lymph contribute to burn-induced lung injury and may therefore play a role in postburn respiratory failure and suggest that intestinal bacterial overgrowth primes the host such that when animals are exposed to a second stimulus (such as thermal injury) an exaggerated response occurs.

Gut-derived mesenteric lymph but not portal blood increases endothelial cell permeability and promotes lung injury after hemorrhagic shock

OBJECTIVE

To determine whether gut-derived factors leading to organ injury and increased endothelial cell permeability would be present in the mesenteric lymph at higher levels than in the portal blood of rats subjected to hemorrhagic shock. This hypothesis was tested by examining the effect of portal blood plasma and mesenteric lymph on endothelial cell monolayers and the interruption of mesenteric lymph flow on shock-induced lung injury.

SUMMARY BACKGROUND DATA

The absence of detectable bacteremia or endotoxemia in the portal blood of trauma victims casts doubt on the role of the gut in the generation of multiple organ failure. Nevertheless, previous experimental work has clearly documented the connection between shock and gut injury as well as the concept of gut-induced sepsis and distant organ failure. One explanation for this apparent paradox would be that gut-derived inflammatory factors are reaching the lung and systemic circulation via the gut lymphatics rather than the portal circulation.

METHODS

Human umbilical vein endothelial cell monolayers, grown in two-compartment systems, were exposed to media, sham-shock, or postshock portal blood plasma or lymph, and permeability to rhodamine (10K) was measured. Sprague-Dawley rats were subjected to 90 minutes of sham or actual shock and shock plus lymphatic division (before and after shock). Lung permeability, pulmonary myeloperoxidase levels, alveolar apoptosis, and bronchoalveolar fluid protein content were used to quantitate lung injury.

RESULTS

Postshock lymph increased endothelial cell monolayer permeability but not postshock plasma, sham-shock lymph/plasma, or medium. Lymphatic division before hemorrhagic shock prevented shock-induced increases in lung permeability to Evans blue dye and alveolar apoptosis and reduced pulmonary MPO levels. In contrast, division of the mesenteric lymphatics at the end of the shock period but before reperfusion ameliorated but failed to prevent increased lung permeability, alveolar apoptosis, and MPO accumulation.

CONCLUSIONS

Gut barrier failure after hemorrhagic shock may be involved in the pathogenesis of shock-induced distant organ injury via gut-derived factors carried in the mesenteric lymph rather than the portal circulation.