Impact of Chemoprophylaxis on Thromboembolism Following Operative Fixation of Pelvic Fractures

BACKGROUND

Venous thromboembolism (VTE) is a common cause of serious morbidity and mortality. While chemoprophylaxis decreases VTE, there is the theoretical risk of increased hemorrhagic complications. The purpose of this study was to evaluate the impact of preoperative anticoagulation on VTE and bleeding complications in patients with blunt pelvic fractures requiring operative fixation.

METHODS

Patients with blunt pelvic fractures requiring operative fixation over 10.5 years were identified. Patients were stratified by age, severity of shock, operative management, and timing and duration of anticoagulation. Outcomes were evaluated to determine risk factors for bleeding complications and VTE.

RESULTS

310 patients were identified: 212 patients received at least one dose of preoperative anticoagulation and 98 received no preoperative anticoagulation. 68% were male with a mean injury severity score and Glasgow Coma Scale of 26 and 13, respectively. Bleeding complications occurred in 24 patients and 21 patients suffered VTE. Patients with VTE had a greater initial severity of shock (resuscitation transfusions, 4 vs. 2 units, P = .02). Despite longer time to mobilization (4 vs. 3 days, P = .001), patients who received their scheduled preoperative doses within 48 hours of arrival had no significant differences in the number of deep vein thrombosis events (5.2% vs. 5.7%, P = .99), but fewer episodes of pulmonary embolism (PE) (1.5% vs. 6.8%, P = .03) with no difference in bleeding complications (7.5% vs. 8%, P = .87) compared to either patients who had their doses held until after 48 hours of arrival or received no preoperative anticoagulation.

DISCUSSION

Preoperative anticoagulation prior to pelvic fixation reduced the risk of PE without increasing bleeding complications. Preoperative anticoagulation is safe and beneficial in this group of patients.

Is NBATS-2 up to the Task? Actual vs. Predicted Patient Volume Shifts With the Addition of Another Trauma Center

INTRODUCTION

Version 2 of the Needs-Based Assessment of Trauma Systems (NBATS) tool quantifies the impact of an additional trauma center on a region. This study applies NBATS-2 to a system where an additional trauma center was added to compare the tool's predictions to actual patient volumes.

METHODS

Injury data were collected from the trauma registry of the initial (legacy) center and analyzed geographically using ArcGIS. From 2012 to 2014 ("pre-"period), one Level 1 trauma center existed. From 2016 to 2018 ("post-"period), an additional Level 2 center existed. Emergency medical service (EMS) destination guidelines did not change and favored the legacy center for severely injured patients (Injury Severity Score (ISS) >15). NBATS-2 predicted volume was compared to the actual volume received at the legacy center in the post-period.

RESULTS

4068 patients were identified across 14 counties. In the pre-period, 72% of the population and 90% of injuries were within a 45-minute drive of the legacy trauma center. In the post-period, 75% of the total population and 90% of injuries were within 45 minutes of either trauma center. The post-predicted volume of severely injured patients at the legacy center was 434, but the actual number was 809. For minor injuries (ISS £15), NBATS-2 predicted 581 vs. 1677 actual.

CONCLUSION

NBATS-2 failed to predict the post-period volume changes. Without a change in EMS destination guidelines, this finding was not surprising for severely injured patients. However, the 288% increase in volume of minor injuries was unexpected. NBATS-2 must be refined to assess the impact of local factors on patient volume.

Long-Term Analysis of Functional Outcomes in Traumatic Brain Injury Patients

INTRODUCTION

Traumatic brain injury (TBI) remains a significant cause of morbidity and mortality. The purpose of this study is to examine outcomes after discharge and identify factors from the index admission that may contribute to long-term mortality.

METHODS

The study population is composed of patients who survived to discharge from a previously published study examining TBI. Demographics, injury severity, and length of stay were abstracted from the index study. Phone surveys of surviving patients were performed to evaluate each patient's Glasgow Outcome Scale-Extended (GOSE). Patients who were deceased at the time of the survey were compared with those who were alive.

RESULTS

1615 patients were alive at the end of the first study period and 211 (13%) comprised the study population. Overall, the median age was 54 years, and the majority were male (74%). The median time to follow-up was 80 months. The population was severely injured, with a median injury severity score (ISS) of 25 and a median head abbreviated injury score (AIS) of 4. Overall mortality was 57%. The group that survived at the time of the survey was younger, more injured, less likely to have received beta-blockers (BB) during the index admission, and had a longer time to follow-up. After adjusting for ISS, age, base deficit, and BB, age was the only variable predictive of mortality (HR 1.03; HL 1.02-1.04).

CONCLUSION

Despite being more severely injured, younger patients were more likely to survive to follow-up. Further investigation is needed to determine if aggressive care in older TBI patients in the acute phase leads to good long-term outcomes.

They only come out at night: Impact of time of day on outcomes after penetrating abdominal trauma

Background

Patients who present at night following penetrating abdominal trauma are thought to have more severe injuries and increased risk for morbidity and mortality. The current literature is at odds regarding this belief. The purpose of this study was to evaluate time of day on outcomes following laparotomy for penetrating abdominal trauma.

Methods

Patients undergoing laparotomy following penetrating abdominal trauma over a 12-month period at a level I trauma center were stratified by age, sex, severity of shock, injury, operative complexity, and time of day (DAY = 0700-1900, NIGHT = 1901-0659). Outcomes of damage control laparotomy, ventilator days, intensive care unit length of stay, hospital length of stay, morbidity, and mortality were compared between DAY and NIGHT.

Results

A total of 210 patients were identified: 145 (69%) comprised NIGHT, and 65 (31%) comprised DAY. Overall mortality was 2.9%. Both injury severity and intraoperative transfusions were increased with NIGHT with no difference in morbidity (37% vs 40%, P = 0.63) or mortality (2.1% vs 4.6%, P = 0.31). Adjusting for sex, time of day, injury severity, and operative complexity, only abdominal abbreviated injury severity (odds ratio 1.46; 95% confidence interval 1.07-1.99, P = .019) and operative transfusions (odds ratio 1.18; 95% confidence interval 1.09-1.28, P < .0001) were identified as independent predictors of damage control laparotomy using multivariable logistic regression (area under the curve 0.96).

Conclusion

The majority of operative penetrating abdominal trauma occurs at night with increased injury burden, more operative transfusions, and increased use of damage control laparotomy with no difference in morbidity and mortality. Outcomes at a fully staffed and operational trauma center should not be impacted by time of day.

How to Increase the Burden on Trauma Centers: Implement the 80-hour Work Week

The 80-hour week was implemented in 2003 to improve outcomes and limit errors. We hypothesize that there has been no change in outcomes postimplementation of the restrictions. Outcomes were queried from the trauma registry from 1997 to 2002 (PRE) and 2004 to 2009 (POST). Primary outcomes were mortality, intensive care unit length of stay (ICU LOS), and length of stay (LOS). Patients were stratified based on demographics, blood pressure, heart rate, and injury severity (Injury Severity Score, Glasgow Coma Score, base deficit). Outcomes were then compared PRE with POST. A total of 41,770 patients were admitted during the study period. The mean age was 38 years with most being male (73%) and blunt mechanism (78%). Although patients admitted in the POST period had a slightly higher blood pressure, they were older and had higher injury severity. ICU LOS, LOS, self-pay, and mortality were higher in the POST period. After adjusted analysis, admission in the POST period was no longer a predictor of mortality (odds ratio, 1.02; confidence interval, 0.92 to 1.14). Whereas patients were more slightly more injured in the POST period, the adjusted analysis shows no difference in mortality and both a longer LOS and ICU LOS. Whether the increase is the result of more severe injury in the POST period or less efficient disposition remains to be elucidated. This study adds to the mounting evidence that the implementation of the limits on work hours does not lead to better outcomes.

Radiographic predictors of therapeutic operative intervention after blunt abdominal trauma: the RAPTOR score

PURPOSE

Bowel and mesenteric injuries are rare in patients following blunt abdominal trauma. Computed tomography (CT) imaging has become a mainstay in the work-up of the stable trauma patient. The purpose of this study was to identify radiographic predictors of therapeutic operative intervention for mesenteric and/or bowel injuries in patients after blunt abdominal trauma.

METHODS

All patients with a discharge diagnosis of bowel and/or mesenteric injury after blunt trauma were identified over a 5-year period. Admission CT scans were reviewed to identify potential predictors of bowel and/or mesenteric injury. Patients were then stratified by operative intervention [therapeutic laparotomy (TL) vs. non-therapeutic laparotomy (NTL)] and compared. All potential predictors included in the initial regression model were assigned one point and a score based on the number of predictors was calculated: the radiographic predictors of therapeutic operative intervention (RAPTOR) score.

RESULTS

151 patients were identified. 114 (76%) patients underwent operative intervention. Of these, 75 patients (66%) underwent TL. Multifocal hematoma, acute arterial extravasation, bowel wall hematoma, bowel devascularization, fecalization, pneumoperitoneum and fat pad injury, identified as potential predictors on univariable analysis, were included in the initial regression model and comprised the RAPTOR score. The optimal RAPTOR score was identified as ≥ 3, with a sensitivity, specificity and positive predictive value of 67%, 85% and 86%, respectively. Acute arterial extravasation (OR 3.8; 95% CI 1.2-4.3), bowel devascularization (OR 14.5; 95% CI 11.8-18.4) and fat pad injury (OR 4.5 95% CI 1.6-6.2) were identified as independent predictors of TL (AUC 0.91).

CONCLUSIONS

CT imaging remains vital in assessing for potential bowel and/or mesenteric injuries following blunt abdominal trauma. The RAPTOR score provides a simplified approach to predict the need for early therapeutic operative intervention.

Rectal Injury After Foreign Body Insertion: Secondary Analysis From the AAST Contemporary Management of Rectal Injuries Study Group

BACKGROUND

Retained rectal foreign bodies are a common but incompletely studied problem. This study defined the epidemiology, injury severity, and outcomes after rectal injuries following foreign body insertion.

METHODS

Twenty-two level I trauma centers retrospectively identified all patients sustaining a rectal injury in this AAST multi-institutional trial (2005-2014). Only patients injured by foreign body insertion were included in this secondary analysis. Exclusion criteria were death before rectal injury management or ≤48 h of admission. Demographics, clinical data, and outcomes were collected. Study groups were defined as partial thickness (AAST grade I) versus full thickness (AAST grades II-V) injuries. Subgroup analysis was performed by management strategy (nonoperative versus operative).

RESULTS

After exclusions, 33 patients were identified. Mean age was 41 y (range 18-57), and 85% (n = 28) were male. Eleven (33%) had full thickness injuries and 22 (67%) had partial thickness injuries, of which 14 (64%) were managed nonoperatively and 8 (36%) operatively (proximal diversion alone [n = 3, 14%]; direct repair with proximal diversion [n = 2, 9%]; laparotomy without rectal intervention [n = 2, 9%]; and direct repair alone [n = 1, 5%]). Subgroup analysis of outcomes after partial thickness injury demonstrated significantly shorter hospital length of stay (2 ± 1; 2 [1-5] versus 5 ± 2; 4 [2-8] d, P = 0.0001) after nonoperative versus operative management.

CONCLUSIONS

Although partial thickness rectal injuries do not require intervention, difficulty excluding full thickness injuries led some surgeons in this series to manage partial thickness injuries operatively. This was associated with significantly longer hospital length of stay. Therefore, we recommend nonoperative management after a retained rectal foreign body unless full thickness injury is conclusively identified.

Beta-adrenergic blockade for attenuation of catecholamine surge after traumatic brain injury: a randomized pilot trial

Background

Beta-blockers have been proven in multiple studies to be beneficial in patients with traumatic brain injury. Few prospective studies have verified this and no randomized controlled trials. Additionally, most studies do not titrate the dose of beta-blockers to therapeutic effect. We hypothesize that propranolol titrated to effect will confer a survival benefit in patients with traumatic brain injury.

Methods

A randomized controlled pilot trial was performed during a 24-month period. Patients with traumatic brain injury were randomized to propranolol or control group for a 14-day study period. Variables collected included demographics, injury severity, physiologic parameters, urinary catecholamines, and outcomes. Patients receiving propranolol were compared with the control group.

Results

Over the study period, 525 patients were screened, 26 were randomized, and 25 were analyzed. Overall, the mean age was 51.3 years and the majority were male with blunt mechanism. The mean Injury Severity Score was 21.8 and median head Abbreviated Injury Scale score was 4. Overall mortality was 20.0%. Mean arterial pressure was higher in the treatment arm as compared with control (p=0.021), but no other differences were found between the groups in demographics, severity of injury, severity of illness, physiologic parameters, or mortality (7.7% vs. 33%; p=0.109). No difference was detected over time in any variables with respect to treatment, urinary catecholamines, or physiologic parameters. Glasgow Coma Scale (GCS), Sequential Organ Failure Assessment, and Acute Physiology and Chronic Health Evaluation scores all improved over time. GCS at study end was significantly higher in the treatment arm (11.7 vs. 8.9; p=0.044). Finally, no difference was detected with survival analysis over time between groups.

Conclusions

Despite not being powered to show statistical differences between groups, GCS at study end was significantly improved in the treatment arm and mortality was improved although not at a traditional level of significance. The study protocol was safe and feasible to apply to an appropriately powered larger multicenter study.

Level of evidence

Level 2—therapeutic.

Does lack of thoracic trauma attenuate the severity of pulmonary failure? An 8-year analysis of critically injured patients

PURPOSE

Patients with thoracic trauma are presumed to be at higher risk for pulmonary dysfunction, but adult respiratory distress syndrome (ARDS) may develop in any patient, regardless of associated chest injury. This study evaluated the impact of thoracic trauma and pulmonary failure on outcomes in trauma patients admitted to the intensive-care unit (ICU).

METHODS

All trauma patients admitted to the ICU over an 8-year period were identified. Patients that died within 48 h of arrival were excluded. Patients were stratified by baseline characteristics, injury severity, development of ARDS, and infectious complications. Multiple logistic regression was used to determine variables significantly associated with the development of ARDS.

RESULTS

10,362 patients were identified. After exclusions, 4898 (50%) patients had chest injury and 4975 (50%) did not. 200 (2%) patients developed ARDS (3.6% of patients with chest injury and 0.5% of patients without chest injury). Patients with ARDS were more likely to have chest injury than those without ARDS (87% vs 49%, p < 0.001). However, of the patients without chest injury, the development of ARDS still led to a significant increase in mortality compared to those patients without ARDS (58% vs 5%, p < 0.001). Multiple logistic regression found ventilator-associated pneumonia (VAP) to be the only independent predictor for the development of ARDS in ICU patients without chest injury.

CONCLUSIONS

ARDS development was more common in patients with thoracic trauma. Nevertheless, the development of ARDS in patients without chest injury was associated with a tenfold higher risk of death. The presence of VAP was found to be the only potentially preventable and treatable risk factor for the development of ARDS in ICU patients without chest injury.

Use of Aerosolized Antibiotics in Gram-Negative Ventilator-Associated Pneumonia in Trauma Patients

Ventilator-associated pneumonia (VAP) is associated with significant morbidity (ventilator days, ICU days, and cost) and mortality increase in trauma patients. Multidrug-resistant strains of causative VAP pathogens are becoming increasingly common. Aerosolized antibiotics achieve high alveolar concentrations and provide valuable adjuncts in the treatment of VAP. This study examined the impact of aerosolized antibiotics in the treatment of VAP in trauma patients. Patients with either Acinetobacter baumannii or Pseudomonas aeruginosa VAP over 10 years treated with aerosolized antibiotics (cases) were stratified by age, severity of shock, and injury severity. A frequency-matched (by causative pathogen) control group treated without aerosolized antibiotics was used for comparison. Multivariable logistic regression was used to identify predictors for the use of aerosolized antibiotics. One hundred twenty VAP episodes were identified in 100 patients. Microbiologic resolution was achieved in all patients treated with aerosolized antibiotics. There was no difference in mortality (14.5% vs 15.7%, P = 0.87) and no antibiotic-related complications in either group. Multivariable logistic regression identified VAP persistence and relapse as independent predictors for the use of aerosolized antibiotics. Combined with systemic therapy, aerosolized antibiotics broaden the spectrum of therapy. They are valuable adjuncts with minimal risk of antibiotic resistance and/or systemic complications.

Use of Aerosolized Antibiotics in Gram-Negative Ventilator-Associated Pneumonia in Trauma Patients

Ventilator-associated pneumonia (VAP) is associated with significant morbidity (ventilator days, ICU days, and cost) and mortality increase in trauma patients. Multidrug-resistant strains of causative VAP pathogens are becoming increasingly common. Aerosolized antibiotics achieve high alveolar concentrations and provide valuable adjuncts in the treatment of VAP. This study examined the impact of aerosolized antibiotics in the treatment of VAP in trauma patients. Patients with either Acinetobacter baumannii or Pseudomonas aeruginosa VAP over 10 years treated with aerosolized antibiotics (cases) were stratified by age, severity of shock, and injury severity. A frequency-matched (by causative pathogen) control group treated without aerosolized antibiotics was used for comparison. Multivariable logistic regression was used to identify predictors for the use of aerosolized antibiotics. One hundred twenty VAP episodes were identified in 100 patients. Microbiologic resolution was achieved in all patients treated with aerosolized antibiotics. There was no difference in mortality (14.5% vs 15.7%, P = 0.87) and no antibiotic-related complications in either group. Multivariable logistic regression identified VAP persistence and relapse as independent predictors for the use of aerosolized antibiotics. Combined with systemic therapy, aerosolized antibiotics broaden the spectrum of therapy. They are valuable adjuncts with minimal risk of antibiotic resistance and/or systemic complications.

Chemical venous thromboembolism prophylaxis in neurosurgical patients: an updated systematic review and meta-analysis

OBJECTIVE

Venous thromboembolism (VTE) is a common and potentially life-threatening complication. The risk of serious hemorrhagic complications when starting chemical prophylaxis for VTE prevention is a substantial concern for neurosurgeons. The objective of this study was to perform an updated systematic review and meta-analysis to determine if the rates of VTE and bleeding complications are different in patients undergoing chemoprophylaxis compared with placebo or mechanical prophylaxis alone following cranial or spinal procedures.

METHODS

In February 2016 a systematic literature review was performed identifying 3944 articles from 4 different databases. A random-effects meta-analysis was performed after identifying the articles that met inclusion criteria.

RESULTS

Nine articles that met the inclusion criteria were included. The quality of the studies was good, with all of them being classified as Level 2 evidence, with moderate Jadad scores. A meta-analysis comparing chemoprophylaxis with placebo in the prevention of deep venous thrombosis showed a significant benefit to chemical prophylaxis (OR 0.51, 95% CI 0.37–0.71; p < 0.0001). No significant increase in major intracranial hemorrhage (p = 0.60), major extracranial hemorrhage (p = 0.98), or minor bleeding complications (p = 0.60) was found.

CONCLUSIONS

Based on moderate-to-good quality of evidence, chemoprophylaxis is beneficial in preventing VTE, with no significant increase in either major or minor bleeding complications in patients undergoing cranial and spinal procedures. Further research is needed to determine whether this conclusion holds true for more specific subpopulations.

Faraday-Talbot effect: Alternating phase and circular arrays

A hydrodynamic analog to the optical Talbot effect may be realized on the surface of a vertically shaken fluid bath when a periodic array of pillars protrudes from the fluid surface. When the pillar spacing is twice or one and a half times the Faraday wavelength, we observe repeated images of the pillars projected in front of the array. Sloshing inter-pillar ridges act as sources of Faraday waves, giving rise to self-images. Here, we explore the emergence of Faraday-Talbot patterns when the sloshing ridges between pillars have alternating phases. We present a simple model of linear wave superposition and use it to calculate the expected self-image locations, comparing them to experimental observations. We explore how alternating phase sources affect the Faraday-Talbot patterns for linear and circular arrays of pillars, where curvature allows for magnification and demagnification of the self-imaging pattern. The use of an underlying wavefield is a subject of current interest in hydrodynamic quantum analog experiments, as it may provide a means to trap walking droplets.

Propofol Infusion Syndrome: Efficacy of a Prospective Screening Protocol

Propofol infusion syndrome (PIS) is a potentially lethal complication of propofol marked by rhabdomyolysis, metabolic acidosis, and cardiac arrhythmias or collapse. The objective of this study was to determine the effectiveness of a prospective screening protocol to prevent PIS. All trauma patients admitted who received propofol as a continuous infusion were prospectively screened from November 1, 2013 to December 31, 2015. Variables studied included demographics, injury severity, laboratory values, infusion rates, and mortality. Serum creatine phosphokinase (CPK) and lactate were drawn daily. Propofol was stopped for a positive screen defined as an increase in CPK to greater than 5000 IU/L or lactate greater than 4 mmol/L. Positive and negative cohorts were compared. Two hundred and twenty-five patients met the inclusion criteria and 12 patients (5.3%) had propofol stopped because of elevated CPK. No differences were identified in demographics, transfusions, injury severity, hospital length of stay, or propofol dose. The positive screened group had longer intensive care unit length of stay (20 vs 13 days; P = 0.002) and increased vent days (14.5 vs 10 days; P = 0.008). Max serum osmolality (334 vs 305 mosm/kg; P = 0.049) and max serum CPK (6782 vs 1058 IU/L; P < 0.0001) were higher in the positive cohort. No cases of PIS occurred, and mortality (16.7 vs 15.5%; P = 0.999) was not different between the cohorts. The screening protocol was effective in eliminating PIS. Serial CPK evaluations provided an effective screening tool and serum lactate can be dropped from screening.

Propofol Infusion Syndrome: Efficacy of a Prospective Screening Protocol

Propofol infusion syndrome (PIS) is a potentially lethal complication of propofol marked by rhabdomyolysis, metabolic acidosis, and cardiac arrhythmias or collapse. The objective of this study was to determine the effectiveness of a prospective screening protocol to prevent PIS. All trauma patients admitted who received propofol as a continuous infusion were prospectively screened from November 1, 2013 to December 31, 2015. Variables studied included demographics, injury severity, laboratory values, infusion rates, and mortality. Serum creatine phosphokinase (CPK) and lactate were drawn daily. Propofol was stopped for a positive screen defined as an increase in CPK to greater than 5000 IU/L or lactate greater than 4 mmol/L. Positive and negative cohorts were compared. Two hundred and twenty-five patients met the inclusion criteria and 12 patients (5.3%) had propofol stopped because of elevated CPK. No differences were identified in demographics, transfusions, injury severity, hospital length of stay, or propofol dose. The positive screened group had longer intensive care unit length of stay (20 vs 13 days; P = 0.002) and increased vent days (14.5 vs 10 days; P = 0.008). Max serum osmolality (334 vs 305 mosm/kg; P = 0.049) and max serum CPK (6782 vs 1058 IU/L; P < 0.0001) were higher in the positive cohort. No cases of PIS occurred, and mortality (16.7 vs 15.5%; P = 0.999) was not different between the cohorts. The screening protocol was effective in eliminating PIS. Serial CPK evaluations provided an effective screening tool and serum lactate can be dropped from screening.

Factors Contributing to Morbidity after Combined Arterial and Venous Lower Extremity Trauma

The purpose of this study was to evaluate the impact of management of venous injury on clinical outcomes in patients with combined lower extremity arterial and venous trauma. Patients with common and external iliac, common and superficial femoral, and popliteal artery injuries were identified. Patients who underwent vein repair and those who received vein ligation were compared. The analysis was repeated for those patients who required secondary intervention for their arterial injury and those who did not require secondary intervention. Seventy patients were identified with both arterial and venous injuries: 40 underwent vein ligation and 30 received vein repair. There was no difference in ischemic time between patients undergoing vein repair compared with ligation. Vein ligation did not produce a higher incidence of muscle debridement (10% vs 15%, P = 0.72), necessity for secondary intervention (10% vs 7.5%, P = 0.99), or amputation (3.3% vs 7.5%, P = 0.63). Patients who required secondary intervention had a greater degree of shock on presentation (packed red blood cells (PRBC), 13 units vs 6 units, P = 0.02) and were more likely to require muscle debridement (50% vs 9%, P = 0.02) and amputation (33% vs 3%, P = 0.03). Vein ligation did not impact muscle ischemia or success of arterial repair in patients with combined venous and arterial trauma in the lower extremities. Patient morbidity after extremity vascular trauma is most related to degree of shock.

Factors Contributing to Morbidity after Combined Arterial and Venous Lower Extremity Trauma

The purpose of this study was to evaluate the impact of management of venous injury on clinical outcomes in patients with combined lower extremity arterial and venous trauma. Patients with common and external iliac, common and superficial femoral, and popliteal artery injuries were identified. Patients who underwent vein repair and those who received vein ligation were compared. The analysis was repeated for those patients who required secondary intervention for their arterial injury and those who did not require secondary intervention. Seventy patients were identified with both arterial and venous injuries: 40 underwent vein ligation and 30 received vein repair. There was no difference in ischemic time between patients undergoing vein repair compared with ligation. Vein ligation did not produce a higher incidence of muscle debridement (10% vs 15%, P = 0.72), necessity for secondary intervention (10% vs 7.5%, P = 0.99), or amputation (3.3% vs 7.5%, P = 0.63). Patients who required secondary intervention had a greater degree of shock on presentation (packed red blood cells (PRBC), 13 units vs 6 units, P = 0.02) and were more likely to require muscle debridement (50% vs 9%, P = 0.02) and amputation (33% vs 3%, P = 0.03). Vein ligation did not impact muscle ischemia or success of arterial repair in patients with combined venous and arterial trauma in the lower extremities. Patient morbidity after extremity vascular trauma is most related to degree of shock.

Evolution of the operative management of colon trauma

For any trauma surgeon, colon wounds remain a relatively common, yet sometimes challenging, clinical problem. Evolution in operative technique and improvements in antimicrobial therapy during the past two centuries have brought remarkable improvements in both morbidity and mortality after injury to the colon. Much of the early progress in management and patient survival after colon trauma evolved from wartime experience. Multiple evidence-based studies during the last several decades have allowed for more aggressive management, with most wounds undergoing primary repair or resection and anastomosis with an acceptably low suture line failure rate. Despite the abundance of quality evidence regarding management of colon trauma obtained from both military and civilian experience, there remains some debate among institutions regarding management of specific injuries. This is especially true with respect to destructive wounds, injuries to the left colon, blunt colon trauma and those wounds requiring colonic discontinuity during an abbreviated laparotomy. Some programs have developed data-driven protocols that have simplified management of destructive colon wounds, clearly identifying those high-risk patients who should undergo diversion, regardless of mechanism or anatomic location. This update will describe the progression in the approach to colon injuries through history while providing a current review of the literature regarding management of the more controversial wounds.

The Impact of Early Recurrence on Quality of Life after Cytoreduction with HIPEC

Improved oncological outcomes after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) in highly selected patients have been well documented. The extensive nature of the procedure adversely affects quality of life (QoL). The aim of this study is to longitudinally evaluate QoL following CRS/HIPEC. This is a retrospective review of a prospectively maintained database of patients with peritoneal malignancies undergoing CRS/HIPEC. Clinicopathological data, oncologic outcomes, and QoL were analyzed preoperatively and post-operatively at 2 weeks, and 1, 3, 6, and 12 months. The Functional Assessment of Cancer Therapy-Colorectal instrument was used to determine changes in QoL after CRS/HIPEC and the impact of early recurrence (<12 months) on QoL. Thirty-six patients underwent CRS/HIPEC over 36 months. The median peritoneal cancer index score was 18 and the completeness of cytoreduction-0/1 rate was 97.2 per cent. Postoperative major morbidity was 16.7 per cent with one perioperative death. Disease-free survival was 12.6 months in patients with high-grade tumors versus 31.0 months in those with low-grade tumors (P = 0.03). QoL decreased postoperatively and improved to baseline in six months. Patients with early recurrence had a decrease in global QoL compared with preoperative QoL at 6 (P < 0.03) and 12 months (P < 0.05). This correlation was not found in patients who had not recurred. Patients who undergo CRS/HIPEC have a decrease in QoL that plateaus in 3 to 6 months. Early recurrence adversely impacts QoL at 6 and 12 months. This study emphasizes the importance of patient selection for CRS/HIPEC. The expected QoL trajectory in patients at risk for early recurrence must be carefully weighed against the potential oncological benefit of CRS/HIPEC.

Investigating Cyclooxygenase Inhibition in a Rat Pulmonary Contusion Model: A Laboratory Study Finding No Improvement with Ibuprofen

Minimal advances have been made in the management of pulmonary contusions (PCs). The purpose of this study was to evaluate the impact of cyclooxygenase inhibition on outcomes following PC in a rat model. PC was induced in anesthetized adult rats. Ibuprofen was given to the treatment group (TG) and water was given to the control group (CG). Lung injury was assessed with pulse oximetry, arterial blood gases, CT, and histopathologic examination. Inflammation was measured with both serum and bronchoalveolar lavage (BAL) levels of tumor necrosis factor a and interleukin-6. Rats in the TG did not differ from rats in the CG with respect to oxygenation. Pathologic examination demonstrated a trend toward more inflammatory infiltrate in the CG, yet the sizes of the contusions were larger in the TG. The CG trended toward decreased levels of interleukin-6 in the serum and BAL at both three and seven days. While BAL levels of tumor necrosis factor a were increased in the TG at three days compared to the CG, they trended toward a reduced amount at seven days. Our data do not support cyclooxygenase inhibition for treatment to decrease the respiratory compromise associated with PC in this model of rat PCs.

Impact of Beta-Blockers on Nonhead Injured Trauma Patients

Catecholamine surge after traumatic injury may lead to dysautonomia with increased morbidity. Small retrospective studies have shown potential benefit of beta-blockers (BB) in trauma patients with and without traumatic brain injury (TBI). This study evaluates a large multiply injured cohort without TBI that received BB. Patients were identified from the trauma registry from January 1, 2003 to December 31, 2011. Patients who received >1 dose of BB were compared to controls. Patients with TBI, length of stay (LOS) < 2 days, and prehospital BB were excluded. Outcomes were mortality, intensive care unit (ICU) LOS, and LOS. Stepwise multivariable regression was used to identify variables significantly associated with mortality. During the study period, 19,151 eligible patients were admitted. The mean age was 39 years. Most were male (74%) and most sustained blunt mechanism (75%). A total of 1854 (11%) patients received BB. BB patients had longer LOS (16 vs 6 days), ICU LOS (7 vs 1 days), and higher mortality (2.8 vs 0.5%) (all P < 0.001). Multivariable regression demonstrated no benefit to BB after adjusting for potential confounding characteristics [odds ratio (OR) 0.952; confidence interval (CI) 0.620–1.461]. In conclusion, in this largest study to date, patients receiving BB were older, more severely injured, and had a higher mortality. Unlike TBI patients, multivariable regression showed no benefit from BB in this population.

Impact of Beta-Blockers on Nonhead Injured Trauma Patients

Catecholamine surge after traumatic injury may lead to dysautonomia with increased morbidity. Small retrospective studies have shown potential benefit of beta-blockers (BB) in trauma patients with and without traumatic brain injury (TBI). This study evaluates a large multiply injured cohort without TBI that received BB. Patients were identified from the trauma registry from January 1, 2003 to December 31, 2011. Patients who received >1 dose of BB were compared to controls. Patients with TBI, length of stay (LOS) < 2 days, and prehospital BB were excluded. Outcomes were mortality, intensive care unit (ICU) LOS, and LOS. Stepwise multivariable regression was used to identify variables significantly associated with mortality. During the study period, 19,151 eligible patients were admitted. The mean age was 39 years. Most were male (74%) and most sustained blunt mechanism (75%). A total of 1854 (11%) patients received BB. BB patients had longer LOS (16 vs 6 days), ICU LOS (7 vs 1 days), and higher mortality (2.8 vs 0.5%) (all P < 0.001). Multivariable regression demonstrated no benefit to BB after adjusting for potential confounding characteristics [odds ratio (OR) 0.952; confidence interval (CI) 0.620-1.461]. In conclusion, in this largest study to date, patients receiving BB were older, more severely injured, and had a higher mortality. Unlike TBI patients, multivariable regression showed no benefit from BB in this population.

How to Further Decrease the Efficiency of Care at a Level I Trauma Center: Implement the Amended Resident Work Hours

Work-hour restrictions were amended in 2011 to limit interns to 16 continuous duty hours, essentially requiring a night float system of 12-hour shifts. We hypothesize that there has been no improvement in outcomes after implementation of the amended work-hour restrictions. Outcomes from trauma admissions were queried from the trauma registry from 2009 to 2011 (PRE) and 2011 to 2013 (POST). The primary outcome was mortality with secondary outcomes intensive care unit length of stay (LOS) and LOS. Patients were stratified based on age, mechanism, gender, blood pressure, heart rate, and injury severity (Injury Severity Score, Glasgow Coma Scale, Base Deficit). Outcomes were then compared from admissions PRE to POST. A total of 9178 patients were included in the study population. The mean age was 42 with most being male (72%) and blunt mechanism (81%). Patient populations were well matched except patients in the POST period were slightly older (43 vs 42 years; P = 0.01). Intensive care unit LOS and LOS were higher in the POST period. After adjusted analysis, admission in the POST period was not a predictor of mortality (odds ratio 0.857; confidence interval 0.655–1.12). The POST period was an independent predictor for LOS (β = 0.74; P = 0.002). This study adds to the mounting evidence that the implementation of the amended limits on work hours leads to furthermore decreased efficiency of care.

Synergistic Effect of Combined Hollow Viscus Injuries on Intra-Abdominal Abscess Formation

The strong association between penetrating colon injuries and intra-abdominal abscess (IAA) formation is well established and attributed to high colon bacterial counts. Since trauma patients are rarely fasting at injury, stomach and small bowel colony counts are also elevated. We hypothesized that there is a synergistic effect of increased IAA formation with concomitant stomach and/or colon injuries when compared to small bowel injuries alone. Consecutive patients at a level one trauma center with penetrating small bowel (SB), stomach (S), and/or colon (C) injuries from 1996 to 2012 were reviewed. Logistic regression determined associations with IAA, adjusting for age, gender, Injury Severity Score (ISS), admission Glasgow Coma Score, transfusions, and concurrent pancreas or liver injury. A total of 1518 patients (91% male, ISS = 15.9 ± 8.4) were identified: 496 (33%) SB, 231 (15%) S, 288 (19%) C, 40 (3%) S + SB, 69 (5%) S + C, 338 (22%) C + SB, and 56 (4%) S + C + SB. 148 (10%) patients developed IAA: 4 per cent SB, 9 per cent S, 10 per cent C, 5 per cent S + SB, 22 per cent S + C, 13 per cent C + SB, and 25 per cent S + C + SB. Multiple logistic regression demonstrated that ISS, 24 hour blood transfusions, and concomitant pancreatic or liver injuries were associated with IAA. Compared with reference SB, S or S + SB injuries were no more likely to develop IAA. However, S + C, SB + C, and S + C + SB injuries were significantly more likely to have IAA. In conclusion, combined stomach + colon, small bowel + colon, and stomach, colon, + small bowel injuries have a synergistic effect leading to increased IAA formation after penetrating injuries. Heightened clinical suspicion for IAA formation is necessary in these combined hollow viscus injury patients.

How to Further Decrease the Efficiency of Care at a Level I Trauma Center: Implement the Amended Resident Work Hours

Work-hour restrictions were amended in 2011 to limit interns to 16 continuous duty hours, essentially requiring a night float system of 12-hour shifts. We hypothesize that there has been no improvement in outcomes after implementation of the amended work-hour restrictions. Outcomes from trauma admissions were queried from the trauma registry from 2009 to 2011 (PRE) and 2011 to 2013 (POST). The primary outcome was mortality with secondary outcomes intensive care unit length of stay (LOS)and LOS. Patients were stratified based on age, mechanism, gender, blood pressure, heart rate, and injury severity (Injury Severity Score, Glasgow Coma Scale, Base Deficit). Outcomes were then compared from admissions PRE to POST. A total of 9178 patients were included in the study population. The mean age was 42 with most being male (72%) and blunt mechanism (81%). Patient populations were well matched except patients in the POST period were slightly older (43 vs 42 years; P = 0.01). Intensive care unit LOS and LOS were higher in the POST period. After adjusted analysis, admission in the POST period was not a predictor of mortality (odds ratio 0.857; confidence interval 0.655-1.12). The POST period was an independent predictor for LOS (β = 0.74; P = 0.002). This study adds to the mounting evidence that the implementation of the amended limits on work hours leads to furthermore decreased efficiency of care.

Impact of pathogen-directed antimicrobial therapy for ventilator-associated pneumonia in trauma patients on charges and recurrence

BACKGROUND

Ventilator-associated pneumonia (VAP) represents one of the driving forces behind antibiotic use in the ICU. In a previous study, we established a defined algorithm for treatment of hospital-acquired VAP dictated by the causative pathogen. The purpose of the current study was to evaluate the impact of this algorithm for hospital-acquired VAP on recurrence and charges in trauma patients.

STUDY DESIGN

Patients with VAP secondary to MRSA, Acinetobacter baumannii, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, or Enterobacteriaceae during 5 years subsequent to the previous study were evaluated. All VAP were diagnosed using quantitative cultures of the bronchoalveolar lavage effluent. Duration of antimicrobial therapy was dictated by the causative pathogen. If microbiologic resolution, defined as <10(3) colony-forming units/mL, was achieved, therapy was stopped by day 10. The remainder received 14 days of therapy. Recurrence was defined as >10(5) colony-forming units/mL on subsequent bronchoalveolar lavage performed within 2 weeks after completion of appropriate therapy.

RESULTS

Five hundred and twenty-nine VAP episodes were identified in 381 patients. Overall recurrence was unchanged compared with the previous study (1.5% vs 2%; p = 0.3). There was a decrease in the number of bronchoalveolar lavages performed per patient compared with the previous study (1.6 vs 2.3; p = 0.24) and a reduction of 4.8 antibiotic days per VAP episode compared with the previous study. Both changes resulted in a cumulative reduction of $3,535.04 per patient, for a savings of $1.35 million during the study period.

CONCLUSIONS

Hospital-acquired VAP can be managed effectively by a defined course of therapy dictated by the causative pathogen. Adherence to an established algorithm simplified the management of VAP and contributed to a cumulative reduction in patient charges without impacting recurrence.

Does the mechanism of injury in pediatric blunt trauma patients correlate with the severity of genitourinary organ injury?

INTRODUCTION

Blunt abdominal trauma can result in injury to genitourinary (GU) organs. Children may be more susceptible to some GU injuries due to anatomic differences compared to adults. Mechanism of injury (MOI) has been thought to relate to both the likelihood and severity of GU injury in children, although this has not definitively been proven. Our purpose was to determine if MOI has any correlation to the severity of GU injury in children treated at our institution.

MATERIALS AND METHODS

We reviewed records of all pediatric blunt trauma patients presenting to our institution from January 2005-December 2010 using the LeBonheur Children's Hospital Trauma Registry. All patients with GU injuries were included in this study. Data collected included demographic information, MOI, type and grade of GU injury, associated injuries, and clinical outcome. Continuous variables were tested with ANOVA and categorical variables were tested with chi-square test.

RESULTS

Records of 5151 children with blunt trauma were reviewed; 76 patients were found to have GU organ injury. There were 47 males (61.8%) and 29 females (38.2%). Categories of MOI included motor vehicle accident, sports injury, bicycle accident, all-terrain vehicle accident (ATV), pedestrian struck accident, falls, and animal injury. MOI did not have any statistically significant association with the severity of GU organ injury (p = 0.5159). In addition, there was no association between MOI and either gender or side of injury. There was a statistically significant association between MOI and patient age (p = 0.04); older pediatric patients were more likely to experience GU injury due to sports injury and ATV accidents, where as younger patients were more likely to experience GU injury due to pedestrian struck, bicycle accidents or animal bite.

CONCLUSIONS

Although specific MOI would seem to relate to presence and severity of injury in children, MOI alone does not correlate with the severity of GU organ injury in our pediatric trauma population. Age of pediatric patients is associated with the type of MOI that results in GU organ injury. The possibility of GU injury should be considered in all symptomatic pediatric patients with clinically significant blunt trauma regardless of the exact MOI.

Admission red cell distribution width: a novel predictor of massive transfusion after injury

Admission red cell distribution width (aRDW) has been shown to predict mortality in trauma patients by an unclear mechanism. It has been speculated that aRDW is a marker of chronic health status, but elevated RDW may also reflect recent hemorrhage. We hypothesized that aRDW is a predictor of major hemorrhage in trauma patients. Shock trauma patients at a Level I trauma center over 6.5 years were evaluated. Patients were stratified by aRDW quintile (Q1: less than 13%, Q2: 13.1 to 13.5%, Q3: 13.6 to 14.0%, Q4: 14.1 to 14.9%, Q5: 15.0% or greater). Massive transfusion (MT) was defined as 10 or more packed red blood cells in the first 24 hours. From multiple logistic regression, odds ratios with 95 per cent confidence intervals (CIs) were determined to evaluate the association between aRDW quintile and MT. Three thousand nine hundred ninety-four met study criteria. Overall MT incidence was 10 per cent and in-hospital mortality was 17 per cent. MT and mortality increased in a stepwise fashion by aRDW quintile (P < 0.0001). From logistic regression, a threefold increased odds of MT was associated with aRDW Q4 (CI, 1.81 to 4.92), and a 3.5-fold increased odds of MT was associated with aRDW Q5 (CI, 2.70 to 5.83). aRDW independently predicted MT, suggesting that elevated aRDW is an indicator of major hemorrhage in trauma patients. The association between aRDW and mortality in trauma patients may be explained by acute hemorrhage rather than chronic health status.

Admission Red Cell Distribution Width: A Novel Predictor of Massive Transfusion after Injury

Admission red cell distribution width (aRDW) has been shown to predict mortality in trauma patients by an unclear mechanism. It has been speculated that aRDW is a marker of chronic health status, but elevated RDW may also reflect recent hemorrhage. We hypothesized that aRDW is a predictor of major hemorrhage in trauma patients. Shock trauma patients at a Level I trauma center over 6.5 years were evaluated. Patients were stratified by aRDW quintile (Q1: less than 13%, Q2: 13.1 to 13.5%, Q3: 13.6 to 14.0%, Q4: 14.1 to 14.9%, Q5: 15.0% or greater). Massive transfusion (MT) was defined as 10 or more packed red blood cells in the first 24 hours. From multiple logistic regression, odds ratios with 95 per cent confidence intervals (CIs) were determined to evaluate the association between aRDW quintile and MT. Three thousand nine hundred ninety-four met study criteria. Overall MT incidence was 10 per cent and in-hospital mortality was 17 per cent. MT and mortality increased in a stepwise fashion by aRDW quintile ( P < 0.0001). From logistic regression, a threefold increased odds of MT was associated with aRDW Q4 (CI, 1.81 to 4.92), and a 3.5-fold increased odds of MT was associated with aRDW Q5 (CI, 2.70 to 5.83). aRDW independently predicted MT, suggesting that elevated aRDW is an indicator of major hemorrhage in trauma patients. The association between aRDW and mortality in trauma patients may be explained by acute hemorrhage rather than chronic health status.

How to increase the burden on trauma centers: implement the 80-hour work week

The 80-hour week was implemented in 2003 to improve outcomes and limit errors. We hypothesize that there has been no change in outcomes postimplementation of the restrictions. Outcomes were queried from the trauma registry from 1997 to 2002 (PRE) and 2004 to 2009 (POST). Primary outcomes were mortality, intensive care unit length of stay (ICU LOS), and length of stay (LOS). Patients were stratified based on demographics, blood pressure, heart rate, and injury severity (Injury Severity Score, Glasgow Coma Score, base deficit). Outcomes were then compared PRE with POST. A total of 41,770 patients were admitted during the study period. The mean age was 38 years with most being male (73%) and blunt mechanism (78%). Although patients admitted in the POST period had a slightly higher blood pressure, they were older and had higher injury severity. ICU LOS, LOS, self-pay, and mortality were higher in the POST period. After adjusted analysis, admission in the POST period was no longer a predictor of mortality (odds ratio, 1.02; confidence interval, 0.92 to 1.14). Whereas patients were more slightly more injured in the POST period, the adjusted analysis shows no difference in mortality and both a longer LOS and ICU LOS. Whether the increase is the result of more severe injury in the POST period or less efficient disposition remains to be elucidated. This study adds to the mounting evidence that the implementation of the limits on work hours does not lead to better outcomes.

Propofol infusion syndrome: a lethal condition in critically injured patients eliminated by a simple screening protocol

Propofol infusion syndrome (PIS) is defined by arrhythmia, rhabdomyolysis, lactic acidosis, and unrecognized leads to death. We sought to determine the incidence of PIS in trauma patients and evaluate the efficacy of a prospective screening protocol in this patient population.

MATERIALS AND METHODS

In Phase I of the before-and-after study (1st January, 2005-31st December, 2005), trauma patients who received propofol were evaluated. Records were reviewed for demographics, injury severity, propofol time, dose, and rates, laboratory values, and adverse events. Patients were identified with PIS based on two of the following criteria: (1) cardiac arrhythmia/collapse, (2) metabolic acidosis, (3) rhabdomyolysis, and (4) acute kidney injury. Phase II (1st January, 2006-31st December, 2011) consisted of a prospective screening protocol (elevated lactate or creatine phosphokinase (CPK)) to identify patients at risk for PIS.

RESULTS

207 patients were identified in Phase I. 6 (2.9%) developed PIS with a 50% mortality. No differences were seen in age, gender, or mechanism. PIS patients were more injured (median ISS 44 vs 26, p=0.04; median head AIS 5 vs 4, p=0.003) and received more propofol (median 50,350 vs 9770 mg, p=0.001) with longer infusion times (413 vs 65 h, p=0.001). Sodium, creatinine, and CPK levels were higher in those that developed PIS (160 vs 145 mmol/L, p=0.001; 4.3 vs 1.1mg/dL, p=0.005; 59,871 vs 520 U/L; p=0.002). Pre-screening PIS incidence was 2.9% (6/207), but after screening (January 2006) the incidence dropped to 0.19% (2/1038, p<0.001).

CONCLUSIONS

PIS is a morbid and lethal entity associated with sedation of critically injured patients. A simple screening procedure utilizing serum CPK (<5000 U/L) can essentially eliminate the development of PIS.

Outcomes of operations performed by attending surgeons after overnight trauma shifts

BACKGROUND

To date, work-hour restrictions have not been imposed on attending surgeons in the United States. The purpose of this study was to investigate the impact of working an overnight trauma shift on outcomes of general surgery operations performed the next day by the post-call attending physician.

STUDY DESIGN

Consecutive patients over a 3.5-year period undergoing elective general surgical procedures were reviewed. Procedures were limited to hernia repairs (inguinal and ventral), cholecystectomies, and intestinal operations. Any operations that were performed the day after the attending surgeon had taken an overnight trauma shift were considered post-call (PC) cases; all other cases were considered nonpost-call (NP). Outcomes from the PC operations were compared with those from the NP operations.

RESULTS

There were 869 patients identified; 132 operations were performed PC and 737 were NP. The majority of operations included hernia repairs (46%), followed by cholecystectomies (35%), and intestinal procedures (19%). Overall, the PC operations did not differ from the NP operations with respect to complication rate (13.7% vs 13.5%, p = 0.93) or readmission within 30 days (5% vs 6%, p = 0.84). Additionally, multivariable logistic regression failed to identify an association between PC operations and the development of adverse outcomes. Follow-up was obtained for an average of 3 months.

CONCLUSIONS

Performance of general surgery operations the day after an overnight in-hospital trauma shift did not affect complication rates or readmission rates. At this time, there is no compelling evidence to mandate work-hour restrictions for attending general surgeons.

Characterization of Lactobacillus reuteri interaction with milk fat globule membrane components in dairy products

A set of methods has been developed to study the adhesion between four Lactobacillus reuteri strains and the milk fat globule membrane (MFGM) components in dairy products. By combining sucrose density gradient (SDG) centrifugation and bacterial DNA quantification it was found which strains of L. reuteri were more strongly associated with the dairy products, and the results were corroborated by direct binding rate and force measurements made with optical tweezers. It was determined that strong binding was associated with hydrophobicity of the bacteria and that this hydrophobicity is correlated with the presence of LiCl-extractable protein on the surface of the bacteria. Confocal laser scanning microscopy (CLSM) allowed for the visualization of interactions between bacteria and MFGM. This study demonstrates that these methods can be used in combination to characterize, both qualitatively and quantitatively, the adhesion of lactic acid bacteria strains in dairy products.

Pattern stabilization through parameter alternation in a nonlinear optical system

We report the first experimental realization of pattern formation in a spatially extended nonlinear system when the system is alternated between two states, neither of which exhibits patterning. Dynamical equations modeling the system are used for both numerical simulations and a weakly nonlinear analysis of the patterned states. The simulations show excellent agreement with the experiment. The nonlinear analysis provides an explanation of the patterning under alternation and accurately predicts both the observed dependence of the patterning on the frequency of alternation and the measured spatial frequencies of the patterns.

Stochastic resonance on two-dimensional arrays of bistable oscillators in a nonlinear optical system

We describe an experimental realization of stochastic resonance in two-dimensional arrays of coupled nonlinear oscillators. The experiment is implemented using an optoelectronic system composed of a liquid crystal light valve in a feedback loop with external, spatially variable noise being added through a liquid crystal display. The behavior of the system differs from previously studied uniform arrays, showing a high signal-to-noise ratio at the output for a broad range of input noise. We show that this behavior is qualitatively the same as that exhibited by computer models where the nonlinear elements of the array have a distribution of biases applied to their switching thresholds.

Spiritual well-being and personality

The hypothesis that High and Low Spiritual Well-being groups have different personality profiles was tested with 319 psychology undergraduates (132 men and 187 women who completed the Revised NEO Personality Inventory and the Spiritual Well-being Scale for partial course credit. Univariate analyses of variance indicated that the High Spiritual Well-being group scored lower on Neuroticism and higher or Extraversion, Agreeableness. and Conscientiousness than the Low Spiritual Well-being group. Multivariate analysis of variance indicated that the two groups had significantly different personality profiles, supporting the hypothesis.

Personality profiles of environmentally responsible groups

The hypothesis that groups high and low on environmental responsibility have different personality profiles was tested using responses of 319 introductory psychology students (132 men and 187 women) who completed the ECOSCALE and the Revised NEO Personality Inventory for partial course credit. Results of discriminant function analysis supported the hypothesis, indicating that groups scoring high and low on Environmental Responsibility had significantly different personality profiles and that the standard discriminant function coefficients were quite substantial (> or = .50) for Openness (.72) and Agreeableness (.50).

Stochastic resonance in two-dimensional arrays of coupled nonlinear oscillators

In this Brief Report we report the results of computer simulations on the periodic and noise driving of two-dimensional square arrays of coupled nonlinear oscillators. We find significant improvement in the output of these arrays over their one-dimensional counterparts (quantified by signal-to-noise ratio in the power spectrum at the frequency of the periodic driving). We also find that, within the limited resolution of our simulations, the one-dimensional scaling laws proposed by Lindner et al. [Phys. Rev. E 53, 2081 (1996)] seem to hold quite well for two-dimensional arrays.

Hardiness and major personality factors

This study tested Maddi and Khoshaba's 1994 hypothesis that Hardiness is an index of mental health. A sample of 241 undergraduates (103 men and 138 women) completed the Dispositional Resilience Scale, the Revised NEO Personality Inventory, and the Psychopathology-5 Scales. Using the individual median scores on the three subscales (Commitment, Control, and Challenge) of the Dispositional Resilience Scale, the High Hardiness group was obtained by identifying the individuals who scored above the medians on all the three subscales, whereas the Low Hardiness group were those who scored consistently below the medians on all the three subscales. Multivariate analysis of variance performed for the two hardiness groups using the scales from each personality inventory indicated that the two groups had significantly different mean profiles on the NEO Personality Inventory as well as the Psychopathology-5 Scales. Combined discriminant function analysis performed for the two hardiness groups using all the 10 scales from the two personality inventories indicated that the two groups had significantly different mean profiles and that the standard discriminant function coefficients were substantial (> .3) for the NEO Personality Inventory Openness (.65) and Conscientiousness (.49) scales and the Psychopathology-5 Positive Emotionality (.56) and Psychoticism (-.36) scales, supporting the tested hypothesis.

Type A behavior and the five-factor model of personality

The hypothesis that people classified as Type A and Type B have different personality profiles based on five major personality factors (Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness) was tested using the Student Jenkins Activity Survey and the Revised NEO Personality Inventory. Results based on discriminant function analysis of data from 243 psychology undergraduates (105 males and 138 females) strongly supported the hypothesis indicating that Type A and Type B groups have significantly different Revised NEO Personality Inventory profiles and that the standardized discriminant function coefficients were large for Agreeableness and Conscientiousness and moderately large for Extraversion.