Disparate potential for readmission prevention exists among inpatient and outpatient procedures in a minimally invasive surgery practice

BACKGROUND

Administrators have focused on decreasing postoperative readmissions for cost reduction without fully understanding their preventability. This study describes the development and implementation of a surgeon-led readmission review process that assessed preventability.

METHODS

A gastrointestinal surgical group at a tertiary referral hospital developed and implemented a template to analyze inpatient and outpatient readmissions. Monthly stakeholder assessments reviewed and categorized readmissions as potentially preventable or not preventable. Continuous variables were examined by the Student's t test and reported as means and standard deviations. Categorical variables were examined by the Pearson χ2 statistic and Fisher's exact test.

RESULTS

There were 61 readmission events after 849 inpatient operations (7.2%) and 16 after 856 outpatient operations (1.9%), the latter of which were all classified as potentially preventable. Colorectal procedures represented 65.6% of readmissions despite being only 37.2% of all cases. The majority (67.2%) of readmission events were not preventable. Compared to the not-preventable group, the potentially preventable group experienced more dehydration (30.0% vs 9.8%, P = .045) and ileostomy creation (78.6% vs 33.3%, P = .017). The potential for outpatient management to prevent readmission was significantly higher in the potentially preventable group (40.0% vs 0.0%, P < .001), as was premature discharge prevention (35.0% vs 0.0%, P < .001).

CONCLUSION

The use of the standardized template developed for analyzing readmission events after inpatient and outpatient procedures identified a disparate potential for readmission prevention. This finding suggests that a singular focus on readmission reduction is misguided, with further work needed to evaluate and implement appropriate quality-based strategies.

A resident robotic curriculum utilizing self-selection and a web-based feedback tool

To describe an obstetrics and gynecology residency robotic curriculum, facilitated by a web-based feedback and case-tracking tool, allowing for self-selection into advanced training. Phase I (Basic) was required for all residents and included online training modules, online assessment, and robotic bedside assistant dry lab. Phase II (Advanced) was elective console training. Before live surgery, 10 simulation drills completed to proficiency were required. A web-based tool was used for surgical feedback and case-tracking. Online assessments, drill reports, objective GEARS assessments, subjective feedback, and case-logs were reviewed (7/2018-6/2019). A satisfaction survey was reviewed. Twenty four residents completed Phase I training and 10 completed Phase II. To reach simulation proficiency, residents spent a median of 4.1 h performing required simulation drills (median of 10 (3, 26) attempts per drill) before live surgery. 128 post-surgical feedback entries were completed after performance as bedside assistant (75%, n = 96) and console surgeon (5.5%, n = 7). The most common procedure was hysterectomy 111/193 (58%). Resident console surgeons performed portions of 32 cases with a mean console time of 34.6 ± 19.5 min. Mean GEARS score 20.6 ± 3.7 (n = 28). Mean non-technical feedback results: communication (4.2 ± 0.8, n = 61), workload management (3.9 ± 0.9, n = 54), team skills (4.3 ± 0.8, n = 60). Residents completing > 50% of case assessed as "apprentice" 38.5% or "competent" 23% (n = 13). After curriculum change, 100% of surveyed attendings considered residents prepared for live surgical training, vs 17% (n = 6) prior to curriculum change [survey response rate 27/44 (61%)]. Attendings and residents were satisfied with curriculum; 95% and recommended continued use 90% (n = 19).This two-phase robotic curriculum allows residents to self-select into advanced training, alleviating many challenges of graduated robotic training.

Unseen Burden of Injury: Post-Hospitalization Mortality in Geriatric Trauma Patients

BACKGROUND/OBJECTIVES

Older adults are at risk for adverse outcomes after trauma, but little is known about post-acute survival as state and national trauma registries collect only inpatient or 30-day outcomes. This study investigates long-term, out-of-hospital mortality in geriatric trauma patients.

METHODS

Level I Trauma Center registry data were matched to the US Social Security Death Index (SSDI) to determine long-term and out-of-hospital outcomes of older patients. Blunt trauma patients aged ≥65 were identified from 2009 to 2015 in an American College of Surgeons Level 1 Trauma Center registry, n = 6289 patients with an age range 65-105 years, mean age 78.5 ± 8.4 years. Dates of death were queried using social security numbers and unique patient identifiers. Demographics, injury, treatments, and outcomes were compared using descriptive and univariate statistics.

RESULTS

Of 6289 geriatric trauma patients, 505 (8.0%) died as an inpatient following trauma. Fall was the most common mechanism of injury (n = 4757, 76%) with mortality rate of 46.5% at long-term follow-up; motor vehicle crash (MVC) (n = 1212, 19%) had long-term mortality of 27.6%. Overall, 24.1% of patients died within 1 year of trauma. Only 8 of 488 patients who died between 1 and 6 months post-trauma were inpatient. Mortality rate varied by discharge location: 25.1% home, 36.4% acute rehabilitation, and 51.5% skilled nursing facility, P < .0001.

CONCLUSION

Inpatient and 30-day mortality rates in national outcome registries fail to fully capture the burden of trauma on older patients. Though 92% of geriatric trauma patients survived to discharge, almost one-quarter had died by 1 year following their injuries.

Complicated Diverticular Disease

The modern management of colonic diverticular disease involves grouping patients into uncomplicated or complicated diverticulitis, after which the correct treatment paradigm is instituted. Recent controversies suggest overlap in management strategies between these two groups. While most reports still support surgical intervention for the treatment of complicated diverticular disease, more data are forthcoming suggesting complicated diverticulitis does not merit surgical resection in all scenarios. Given the significant risk for complication in surgery for diverticulitis, careful attention should be paid to patient and procedure selection. Here, we define complicated diverticulitis, discuss options for surgical intervention, and explain strategies for avoiding operative pitfalls that result in early and late postoperative complications.

Chronic immunosuppressant use in colorectal cancer patients worsens postoperative morbidity and mortality through septic complications in a propensity-matched analysis

AIM

Chronic immunosuppressant use increases the risk of septic complications after colectomy; however, adverse effects on other organ systems remain poorly understood. The aim of this study was to evaluate the multisystem organ effect(s) of chronic immunosuppressant(s) in colorectal cancer patients.

METHODS

This was a retrospective study. The American College of Surgeons National Surgical Quality Improvement database (2005-2012) was queried. The primary end-points were 30-day mortality and 30-day morbidity after colectomy in patients on chronic immunosuppressant(s) compared to a non-immunosuppressant cohort.

RESULTS

In total, 50 766 patients were identified, with 1203 (2.4%) taking chronic immunosuppressant(s). After propensity matching, 1197 patients in each cohort were evaluated with no differences seen in age, body mass index, male sex, wound classification, emergency case status, the presence of preoperative sepsis or operative time. On outcome analysis, 30-day mortality (5.7% vs 3.4%, P < 0.001) and 30-day overall morbidity (35.4% vs 29.0%, P = 0.001) were higher in patients on chronic immunosuppressant(s). Septic complications (10.6% vs 7.9%, P = 0.02) and surgical site infections (15.3% vs 12.3%, P = 0.03) were elevated with chronic immunosuppressant(s). There were no differences in cardiovascular, pulmonary, renal or neurological complications. Chronic immunosuppressant patients demonstrated longer total hospital stay (11.4 ± 11.7 vs 9.5 ± 9.4 days, P < 0.001) and postoperative length of stay (9.4 ± 9.2 vs 8.1 ± 7.6 days, P < 0.001). The limitation was that this was a retrospective study using a clinical dataset.

CONCLUSION

In this study, immunosuppressant use is associated with worsened infective complications, without contributing to organ-specific complications following colectomy. Significant thought should be given to anastomosis vs stoma creation to possibly prevent worsened morbidity and mortality. Future study is required to determine specific pathways for risk reduction.

Perforated diverticulitis in the setting of ulcerative colitis: An unusual case report

INTRODUCTION

The association of diverticulitis with ulcerative colitis (UC) is rare and not well described. The sequelae of inflammatory bowel disease (IBD) such as perforation and fistula formation can mimic diverticular complications. Therefore, in an IBD patient, it can be difficult to distinguish the etiology of such complications and render definitive care.

PRESENTATION OF CASE

A 43-year-old man with a long history of UC presented with spontaneous sigmoid perforation and subsequent complications of colovesicular and colocutaneous fistulae requiring multiple procedural interventions. Ultimately, the etiology was confirmed as perforated diverticulitis superimposed on severe ulcerative colitis.

DISCUSSION

As perforated diverticulitis superimposed on UC is a rare entity in the current literature and there are many diagnostic difficulties that complicate this scenario. It is important to rule out other entities such as misdiagnosis of IBD or segmental colitis associated with diverticula (SCAD) that may have overlapping features.

CONCLUSION

Although diverticulitis in the setting of UC is an uncommon presentation, it remains important for medical practitioners to consider this scenario when encountering patients who may present in a similar fashion. As such, we put forth a process to aid in a diagnosis and management such that definitive care may not be delayed.

Post-operative morbidity, but not mortality, is worsened by operative delay in septic diverticulitis

PURPOSE

Optimal timing of surgery for acute diverticulitis remains unclear. A non-operative approach followed by elective surgery 6-week post-resolution is favored. However, a subset of patients fail on the non-operative management during index admission. Here, we examine patients requiring emergent operation to evaluate the effect of surgical delay on patient outcomes.

METHODS

Patients undergoing emergent operative intervention for acute diverticulitis were queried using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2005 to 2012. Primary endpoints of 30-day overall morbidity and mortality were evaluated via univariate and multivariate analysis.

RESULTS

Of the 2,119 patients identified for study inclusion, 57.2 % (n = 1212) underwent emergent operative intervention within 24 h, 26.3 % (n = 558) between days 1-3, 12.9 % (n = 273) between days 3-7, and 3.6 % (n = 76) greater than 7 days from admission. End colostomy was performed in 77.4 % (n = 1,640) of cases. Unadjusted age and presence of major comorbidities increased with operative delay. Further, unadjusted 30-day overall morbidity, mortality, septic complications, and post-operative length of stay increased significantly with operative delay. On multivariate analysis, operative delay was not associated with increased 30-day mortality but was associated with increased 30-day overall morbidity.

CONCLUSIONS

Hartmann's procedure has remained the standard operation in emergent surgical management of acute diverticulitis. Delay in definitive surgical therapy greater than 24 h from admission is associated with higher rates of morbidity and protracted post-operative length of stay, but there is no increase in 30-day mortality. Prospective study is necessary to further answer the question of surgical timing in acute diverticulitis.

Elucidating Trainee Effect on Outcomes for General, Gynecologic, and Urologic Oncology Procedures

BACKGROUND AND OBJECTIVES

Surgical complications delay adjuvant therapy in oncology patients. Current literature remains unclear regarding resident effect on postoperative outcomes, with inappropriate coverage possibly endangering patients in spite of attending oversight. We assessed resident postgraduate year (PGY) effect on 30-day overall morbidity in cancer patients undergoing major intra-abdominal and non-abdominal surgery.

METHODS

Patients undergoing non-emergent major intra- and extra-abdominal operations from 2005-2012 were queried using the American College of Surgeons' National Surgical Quality Improvement Program. Attending alone and resident PGY cohorts were compared for demographics, 30-day overall morbidity, mortality, and relevant outcomes.

RESULTS

A total of 156,941 cancer patients undergoing major intra-abdominal (n = 76,385) or major non-abdominal (n = 80,556) procedures were captured. Demographics were clinically similar across attending and PGY levels. Rates of overall morbidity increased significantly with PGY level, along with operative time and length of stay. For major intra-abdominal procedures, all resident levels except PGY2 level adversely affected overall morbidity. Above PGY4 level, resident involvement had a stronger association with adverse outcome than preoperative comorbidities and preoperative chemotherapy. Interestingly, gastric, gall bladder, liver, pancreas, esophageal, and thyroid procedures demonstrated no effect of resident involvement on overall morbidity.

CONCLUSIONS

Resident PGY is independently associated with increased overall morbidity in patients undergoing selected major surgical procedures. Understanding surgical procedures affected by resident involvement will maximize outcomes.

Comparative effectiveness of Roux-en-Y gastric bypass and sleeve gastrectomy in super obese patients

BACKGROUND

The disproportionate increase in the super obese (SO) is a hidden component of the current obesity pandemic. Data on the safety and efficacy of bariatric procedures in this specific patient population are limited. Our aim is to assess the comparative effectiveness of the two most common bariatric procedures in the SO.

METHODS

Using the Bariatric Outcomes Longitudinal Database from 2007 to 2012, we compared SO patients (BMI ≥ 50) undergoing laparoscopic Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Stepwise logistic regression modeling was used to calculate a propensity score to adjust for patient demographics and comorbidities.

RESULTS

We identified 50,987 SO patients who underwent RYGB (N = 42,119) or SG (N = 8868). There was no difference in adjusted overall 30-day complication rate comparing RYGB and SG patients (11.5 vs. 11.1 %, p = 0.250). RYGB patients had higher adjusted rates of 30-day mortality (0.3 vs. 0.2 %, p = 0.042), reoperation (4.0 vs. 2.4 %, p < 0.001), and readmission (6.9 vs. 5.5 %, p < 0.001) compared to SG patients. The percent of total weight loss (%TWL) was significantly higher for RYGB patients compared to SG at 3 months (14.1 vs. 13.1 %, p < 0.001), 6 months (25.2 vs. 22.4 %, p < 0.001), and 12 months (34.5 vs. 29.7 %, p < 0.001). RYGB patients had increased resolution of all measured comorbidities: diabetes mellitus (61.6 vs. 50.8 %, p < 0.001), hypertension (43.1 vs. 34.5 %, p < 0.001), gastroesophageal reflux disease (53.9 vs. 32.5 %, p < 0.001), hyperlipidemia (39.7 vs. 32.5 %, p < 0.001), and obstructive sleep apnea (42.8 vs. 40.6 %, p = 0.058) at 12 months compared to SG patients.

CONCLUSIONS

There are significant differences in comorbidity improvement and resolution as well as weight loss between RYGB and SG in the SO population. There was no difference in overall 30-day complications, but more RYGB patients required readmission and reoperation. However, RYGB was considerably more effective in controlling obesity-related comorbidities. Our results favor performance of RYGB in SO patients of appropriate risk.

Synchronous Ventral Hernia Repair in Patients Undergoing Bariatric Surgery

BACKGROUND

Obesity predisposes patients to abdominal wall hernias. Patients undergoing bariatric surgery are not uncommonly found to have ventral hernias. Synchronous ventral hernia repair (S-VHR) has been reported in 2-5% of patients undergoing bariatric surgery. Studies reporting on the outcomes of S-VHR are limited by sample size. The aim of this study was to assess the effect of S-VHR on surgical site infection (SSI) rate.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database from 2010 to 2011 was queried using Current Procedural Terminology codes for bariatric surgery. Data on patient demographics, comorbidities, procedural events, and postoperative occurrences were analyzed. Thirty-day mortality and morbidity were assessed. Comparisons between laparoscopic Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) were performed.

RESULTS

We identified 17,117 patients who underwent RYGB or SG. S-VHR was performed in 503 (2.94%) patients. S-VHR was independently associated with SSI (odds ratios (OR) 1.65, 95% confidence interval (CI) 1.06-2.58), but not overall morbidity (OR 1.33, 95% CI 0.96-1.86). Four hundred thirty-three patients with RYGB and 70 with SG had S-VHR. Serious morbidity (3.5 vs. 5.7%, p = 0.32) and overall morbidity (8.3 vs. 8.6%, p = 0.942) were similar. After controlling for baseline comorbidities, there was no significant effect of procedure type on SSI (OR 0.38, 95% CI 0.05-2.91).

CONCLUSIONS

S-VHR is associated with an increase in SSI but not overall morbidity. There is no significant difference in the SSI rate between RYGB and SG. Larger studies are needed to definitively assess a potential difference in the wound infection rate between RYGB and SG.

Obstructing ventral hernias are not independently associated with surgical site infections

BACKGROUND

Delayed operative intervention in the setting of adhesive bowel obstruction has been recently shown to increase the rate of surgical site infection (SSI), raising the concern for bacterial translocation. The effect of obstruction on SSI rate in patients with ventral hernia is unknown. The aim of this study was to assess the association between bowel obstruction and SSI in patients undergoing ventral hernia repair (VHR).

MATERIALS AND METHODS

This study is a retrospective database review. Patients undergoing isolated VHR from 2005-2011 were identified from the American College of Surgeons' National Surgical Quality Improvement Program database. Demographics, comorbidities, and 30-d outcomes were analyzed. Multivariate logistic regression was used for variables with a P value of <0.1.

RESULTS

A total of 68,811 patients underwent isolated VHR; 53.1% were male with mean age of 53 ± 15 y and body mass index of 32 ± 8. Hernia-related obstruction was found in 17,058 (24.8%). In patients with obstruction, SSI was more frequent (3.2% versus 2.6%, P < 0.001). Obesity, advanced age, vascular, pulmonary, hepatic, renal disease, and diabetes were more prevalent. After controlling for confounding baseline variables, bowel obstruction was not independently associated with SSI (odds ratio, 0.983, 95% confidence interval, 0.872-1.107). Subgroup analysis of clean classified cases also demonstrated the lack of independent association between obstruction and SSI.

CONCLUSIONS

Obstruction in patients undergoing VHR is not independently associated with SSI. Our results suggest that mesh implantation remains a viable option in this setting. Other confounding comorbid conditions should be assessed at the time of surgical intervention to identify patients appropriate for mesh repair.

Delayed repair of obstructing ventral hernias is associated with higher mortality and morbidity

BACKGROUND

Patients presenting with ventral hernia-related obstruction are commonly managed with emergent ventral hernia repair (VHR). Selected patients with resolution of obstruction may be managed in a delayed manner. This study sought to assess the effect of delay on VHR outcomes.

METHODS

The American College of Surgeons' National Surgical Quality Improvement Program database from 2005 to 2011 was queried using diagnosis codes for ventral hernia with obstruction. Those who underwent repair over 24 hours after admission were classified as delayed repair. Preoperative comorbid conditions, American Society of Anesthesiology (ASA) scores, and 30-day outcomes were evaluated.

RESULTS

We identified 16,881 patients with a mean age of 58 ± 15 years and body mass index of 36 ± 10. Delayed repair occurred in 27.7% of the patients. After controlling for comorbidities and ASA score, delayed VHR was independently associated with mortality (odds ratio [OR] 1.9, 95% confidence interval [CI] 1.41 to 2.48, P < .001), morbidity (OR 1.4, 95% CI 1.24 to 1.50, P < .001), surgical site infection (OR 1.2, 95% CI 1.03 to 1.35, P = .016), and concurrent bowel resection (OR 1.2, 95% CI 1.03 to 1.34, P = .016).

CONCLUSIONS

VHR for obstructed patients is frequently performed over 24 hours after admission. After adjusting for comorbid conditions and ASA score, delayed VHR is independently associated with worse outcomes. Prompt repair after appropriate resuscitation should be the management of choice.

What are the results of colonic volvulus surgery?

BACKGROUND

Operative results of volvulus are largely unknown because of infrequent diagnosis.

OBJECTIVE

We examined the results of operative intervention for colonic volvulus.

DESIGN

We merged trackable data from the California Inpatient Database with Supplemental Files for Revisit Analyses between January 1, 2005, and December 31, 2007.

SETTINGS

Trackable data from California discharge records.

PATIENTS

We identified all of the patients with colonic volvulus who underwent 1 of 4 surgical procedures, including manipulation/fixation of the colon, right colectomy, left colectomy, or total colectomy.

MAIN OUTCOME MEASURES

During the 36-month study period, we identified recurrence risk, recurrence requiring reoperation, time to reoperation, stoma formation, disposition on discharge, and in-hospital mortality. Fisher exact, χ(2), and ANOVA tests were used when appropriate.

RESULTS

We identified 2141 patients with colonic volvulus who were undergoing intraoperative manipulation/fixation of the colon (n = 209 (12%)), right (n = 728 (41%)), left (n = 781 (44%)), or total colectomy (n = 56 (3%)). Patients treated with intraoperative manipulation/fixation were younger, more likely to be women, and more likely to have private insurance. Patients who underwent total colectomy had the highest risk of mortality (21%), highest risk of stoma creation (64%), and longest length of stay (18 days); were more likely to be readmitted (9%); and were the most likely to be discharged to a skilled nursing facility (48%). Patients treated with intraoperative manipulation/fixation had the lowest mortality, risk of stoma formation, length of stay, and likelihood of discharge to skilled nursing facility but the highest risk of subsequent procedures for volvulus (26%) over a follow-up ranging from 0 to 687 days.

LIMITATIONS

This study was limited by retrospective study design, heterogeneous patient factors, and inability to identify the time of last follow-up.

CONCLUSIONS

The majority of patients with volvulus underwent a resectional procedure. A subset without resection had favorable initial outcomes but remained at high risk for subsequent procedures. There may be a potential role for evaluating intraoperative manipulation/fixation in a small subset of patients with colonic volvulus.

All things not being equal: readmission associated with procedure type

BACKGROUND

There is an accelerated effort to reduce hospital readmissions despite minimal data detailing risk factors associated with this outcome.

MATERIALS AND METHODS

We analyzed National Surgical Quality Improvement Project data from January 1, 2011-December 31, 2011, evaluating all patients undergoing one of 34 targeted operative procedures across all surgical specialties. Multivariate regression models of risk for readmission were developed including targeted procedure codes, demographic variables, preoperative variables, intraoperative variables, and postoperative adverse events. Our main outcome measure was hospital readmission.

RESULTS

A total of 217, 389 patients met study inclusion criteria. Minimal associations existed between patient factors and risk of readmission. Adverse events including unplanned operating room return (odds ratio [OR] 8.5; confidence interval [CI] 8.0-9.0), pulmonary embolism (OR 8.2; CI 7.1-9.6), deep incisional infection (OR 7.5; CI 6.7-8.5), and organ space infection (OR 5.8; CI 5.3-6.3) were associated with increased risk of readmission. Our data suggest the type of procedure performed is significantly associated with risk of readmission. Furthermore, multivariate analysis revealed procedures, involving the pancreas, rectum, bladder, and lower extremity vascular bypass, were associated with the highest risk of readmission.

CONCLUSIONS

Postoperative complications demonstrated stronger association with readmission than patient factors. Focused analysis of higher risk procedures may provide insight into strategies for risk reduction.

Update on the critical care management of severe burns

Care of the severely injured patient with burn requires correct diagnosis, appropriately tailored resuscitation, and definitive surgical management to reduce morbidity and mortality. Currently, mortality rates related to severe burn injuries continue to steadily decline due to the standardization of a multidisciplinary approach instituted at tertiary health care centers. Prompt and accurate diagnoses of burn wounds utilizing Lund-Browder diagrams allow for appropriate operative and nonoperative management. Coupled with diagnostic improvements, advances in resuscitation strategies involving rates, volumes, and fluid types have yielded demonstrable benefits related to all aspects of burn care. More recently, identification of comorbid conditions such as inhalation injury and malnutrition have produced appropriate protocols that aid the healing process in severely injured patients with burn. As more patients survive larger burn injuries, the early diagnosis and successful treatment of secondary and tertiary complications are becoming commonplace. While advances in this area are exciting, much work to elucidate immune pathways, diagnostic tests, and effective treatment regimens still remain. This review will provide an update on the critical care management of severe burns, touching on accurate diagnosis, resuscitation, and acute management of this difficult patient population.

The leptin system: a potential target for sepsis induced immune suppression

Sepsis, which is defined as a systemic inflammatory response syndrome that occurs during infection, is associated with several clinical conditions and high mortality rates. As sepsis progresses immune paralysis can become severe, leaving an already vulnerable patient ill equipped to eradicate primary or secondary infections. At present the predominant treatments for sepsis have not demonstrated convincing efficacy of decreased mortality. During sepsis, it has been observed that leptin levels initially increase but subsequently decline. A body of evidence has demonstrated that central or systemic leptin can beneficially regulate immune function. In this report expression of leptin and its receptor, signaling, and function on leukocytes will be reviewed. Furthermore, the effects mediated by central and systemic leptin during sepsis will be reviewed. Altogether, the ability of leptin to beneficially enhance inflammation and the host response during sepsis supports its use as a therapeutic agent, particularly during the latter phases of the syndrome.

CXC chemokine receptor-1 is expressed by hepatocytes and regulates liver recovery after hepatic ischemia/reperfusion injury

CXC chemokines mediate hepatic inflammation and injury following ischemia/reperfusion (I/R). More recently, signaling through CXC chemokine receptor-2 (CXCR2) was shown to delay liver recovery and repair after I/R injury. The chemokine receptor CXCR1 shares ligands with CXCR2, yet nothing is known about its potential role in liver pathology. In the present study, we examined the role of CXCR1 in the injury and recovery responses to I/R using a murine model. CXCR1 expression was undetectable in livers of sham-operated mice. However, after ischemia CXCR1 expression increased 24 hours after reperfusion and was maximal after 96 hours of reperfusion. CXCR1 expression was localized largely to hepatocytes. In order to assess the function of CXCR1, CXCR2(-/-) mice were treated with the CXCR1/CXCR2 antagonist, repertaxin. Prophylactic treatment with repertaxin had no effect on acute inflammation or liver injury. However, when repertaxin was administered 24 hours postreperfusion there was a significant increase in hepatocellular injury and a delay in recovery compared to control-treated mice. CXCR1(-/-) mice also demonstrated delayed recovery and regeneration after I/R when compared to wild-type mice. In vitro, hepatocytes from CXCR2(-/-) mice that were stimulated to express CXCR1 showed increased proliferation in response to ligand. Hepatocyte proliferation was decreased in CXCR1(-/-) mice in vivo.

CONCLUSION

This is the first report to show that CXCR1 expression is induced in hepatocytes after injury. Furthermore, the data suggest that CXCR1 has divergent effects from CXCR2 and appears to facilitate repair and regenerative responses after I/R injury.

Early infection during burn-induced inflammatory response results in increased mortality and p38-mediated neutrophil dysfunction

Following burn injury, the host is susceptible to bacterial infections normally cleared by healthy patients. We hypothesized that during the systemic immune response that follows scald injury, the host's altered immune status increases infection susceptibility. Using a murine model of scald injury under inhaled anesthesia followed by intraperitoneal infection, we observed increased neutrophil numbers and function at postburn day (PBD) 1 compared with sham-burned and PBD4 mice. Further, increased mortality, bacteremia, and serum IL-6 were observed in PBD1 mice after Pseudomonas aeruginosa (PA) infection compared with sham-burned and PBD4 mice infected with PA. To examine these disparate responses, we investigated neutrophils isolated at 5 and 24 h following PA infection from PBD1 and sham-burned mice. Five hours after infection, there was no significant difference in number of recruited neutrophils; however, neutrophils from injured mice had decreased activation, active-p38, and oxidative burst compared with sham-burned mice. In direct contrast, 24 h after infection, we observed increased numbers, active-p38, and oxidative burst of neutrophils from PBD1 mice. Finally, we demonstrated that in neutrophils isolated from PBD1 mice, the observed increase in oxidative burst was p38 dependent. Altogether, neutrophil activation and function from thermally injured mice are initially delayed and later exacerbated by a p38-dependent mechanism. This mechanism is likely key to the observed increase in bacterial load and mortality of PBD1 mice infected with PA.

IL-7 promotes T cell viability, trafficking, and functionality and improves survival in sepsis

Sepsis is a highly lethal disorder characterized by widespread apoptosis-induced depletion of immune cells and the development of a profound immunosuppressive state. IL-7 is a potent antiapoptotic cytokine that enhances immune effector cell function and is essential for lymphocyte survival. In this study, recombinant human IL-7 (rhIL-7) efficacy and potential mechanisms of action were tested in a murine peritonitis model. Studies at two independent laboratories showed that rhIL-7 markedly improved host survival, blocked apoptosis of CD4 and CD8 T cells, restored IFN-gamma production, and improved immune effector cell recruitment to the infected site. Importantly, rhIL-7 also prevented a hallmark of sepsis (i.e., the loss of delayed-type hypersensitivity), which is an IFN-gamma- and T cell-dependent response. Mechanistically, rhIL-7 significantly increased the expression of the leukocyte adhesion markers LFA-1 and VLA-4, consistent with its ability to improve leukocyte function and trafficking to the infectious focus. rhIL-7 also increased the expression of CD8. The potent antiapoptotic effect of rhIL-7 was due to increased Bcl-2, as well as to a dramatic decrease in sepsis-induced PUMA, a heretofore unreported effect of IL-7. If additional animal studies support its efficacy in sepsis and if current clinical trials continue to confirm its safety in diverse settings, rhIL-7 should be strongly considered for clinical trials in sepsis.

Neutrophils are significant producers of IL-10 during sepsis

Sepsis is a syndrome involving systemic inflammation as well as an infectious focus. Accordingly, the host immune response to sepsis involves complex leukocyte interplay that is incompletely understood. It is known that the immunoregulatory cytokine, IL-10, is rapidly expressed during the early stages of sepsis. In a murine model of sepsis, we sought to elucidate which leukocytes are early IL-10 producers. Using a novel IL-10 transcriptional reporter mouse, we observed that splenic leukocytes produced little IL-10. At the site of infection, peritoneal neutrophils produced the highest levels of IL-10 among leukocytes. Using cytokine antibody labeling, we further show that peritoneal neutrophils had high amounts of intracellular IL-10. We next depleted neutrophils and found a 40% decrease in peritoneal IL-10 levels. Altogether, this report demonstrates that among leukocytes, neutrophils are significant contributors of IL-10 at the site of infection during sepsis.

Divergent adaptive and innate immunological responses are observed in humans following blunt trauma

BACKGROUND

The immune response to trauma has traditionally been modeled to consist of the systemic inflammatory response syndrome (SIRS) followed by the compensatory anti-inflammatory response syndrome (CARS). We investigated these responses in a homogenous cohort of male, severe blunt trauma patients admitted to a University Hospital surgical intensive care unit (SICU). After obtaining consent, peripheral blood was drawn up to 96 hours following injury. The enumeration and functionality of both myeloid and lymphocyte cell populations were determined.

RESULTS

Neutrophil numbers were observed to be elevated in trauma patients as compared to healthy controls. Further, neutrophils isolated from trauma patients had increased raft formation and phospho-Akt. Consistent with this, the neutrophils had increased oxidative burst compared to healthy controls. In direct contrast, blood from trauma patients contained decreased naïve T cell numbers. Upon activation with a T cell specific mitogen, trauma patient T cells produced less IFN-gamma as compared to those from healthy controls. Consistent with these results, upon activation, trauma patient T cells were observed to have decreased T cell receptor mediated signaling.

CONCLUSIONS

These results suggest that following trauma, there are concurrent and divergent immunological responses. These consist of a hyper-inflammatory response by the innate arm of the immune system concurrent with a hypo-inflammatory response by the adaptive arm.

The cannabinoid receptor 2 is critical for the host response to sepsis

Leukocyte function can be modulated through the cannabinoid receptor 2 (CB2R). Using a cecal ligation and puncture (CLP) model of sepsis, we examined the role of the CB2R during the immune response to an overwhelming infection. CB2R-knock out (KO) mice showed decreased survival as compared with wild-type mice. CB2R-KO mice also had increased serum IL-6 and bacteremia. Twenty-four hours after CLP, the CB2R-deficient mice had increased lung injury. Additionally, CB2R-deficiency led to increased neutrophil recruitment, decreased neutrophil activation, and decreased p38 activity at the site of infection. Consistent with a novel role for CB2R in sepsis, CB2R-agonist treatment in wild-type mice increased the mean survival time in response to CLP. Treatment with CB2R-agonist also decreased serum IL-6 levels, bacteremia, and damage to the lungs compared with vehicle-treated mice. Finally, the CB2R agonist decreased neutrophil recruitment, while increasing neutrophil activation and p38 activity at the site of infection compared with vehicle-treated mice. These data suggest that CB2R is a critical regulator of the immune response to sepsis and may be a novel therapeutic target.