Host Microbiome Threats in the Intensive Care Unit

Human microbiota demonstrate diversity and balance that is adaptive for the host and supports maintaining homeostasis. Although acute illness or injury may derange microbiota diversity and the proportion of potentially pathogenic microbes, that derangement may be further exacerbated by commonly deployed intensive care unit (ICU) therapeutic and practices. These include antibiotic administration, delayed luminal nutrition, acid suppression, and vasopressor infusion. Furthermore, the local ICU microbial ecology, regardless of disinfection practices, shapes the patient's microbiota, especially with the acquisition of multi-drug-resistant pathogens. Current approaches to protect a normal microbiome, or restore a deranged one, are part of a multifaceted approach that may include antibiotic stewardship and infection control practices as microbiome-directed therapeutics emerge.

Sepsis and postoperative surgical site infections

Surgical site infections remain a significant cause of morbidity and mortality. High-quality evidence supports several measures to prevent surgical site infections that should be applied with high compliance, although effective application remains suboptimal. Recognizing high-risk patients and avoiding potential pitfalls in the diagnosis of surgical site infections is paramount in preventing progression to sepsis, particularly in emergency surgical patients with physiologic derangement. A high index of suspicion postoperatively is critical to identify patients with surgical site infections and to prevent failure to rescue.

Emergencies do not shut down during a pandemic: COVID pandemic impact on Acute Care Surgery volume and mortality at a level I trauma center

BACKGROUND

The aim of this study was to evaluate the impact of the COVID-19 pandemic on volume and outcomes of Acute Care Surgery patients, and we hypothesized that inpatient mortality would increase due to COVID+ and resource constraints.

METHODS

An American College of Surgeons verified Level I Trauma Center's trauma and operative emergency general surgery (EGS) registries were queried for all patients from Jan. 2019 to Dec. 2020. April 1st, 2020, was the demarcation date for pre- and during COVID pandemic. Primary outcome was inpatient mortality.

RESULTS

There were 14,460 trauma and 3091 EGS patients, and month-over-month volumes of both remained similar (p > 0.05). Blunt trauma decreased by 7.4% and penetrating increased by 31%, with a concomitant 25% increase in initial operative management (p < 0.001). Despite this, trauma (3.7%) and EGS (2.9-3.0%) mortality rates remained stable which was confirmed on multivariate analysis; p > 0.05. COVID + mortality was 8.8% and 3.7% in trauma and EGS patients, respectively.

CONCLUSION

Acute Care Surgeons provided high quality care to trauma and EGS patients during the pandemic without allowing excess mortality despite many hardships and resource constraints.

Prior Antibiotic Exposure Is Associated With Reoperation After Elective Non-colorectal Surgery

BACKGROUND

Recent antibiotic exposure has previously been associated with poor outcomes following elective surgery. The purpose of this study is to evaluate the impact of prior recent antibiotic exposure in a multicenter cohort of Veterans Affairs patients undergoing elective non-colorectal surgery.

METHODS

This is a retrospective cohort study of the Veterans Affairs Surgical Quality Improvement Program, including elective, non-cardiovascular, non-colorectal surgery from 2013 to 2017. Outpatient antibiotic exposure within 90 days prior to surgery was identified from the Veterans Affairs outpatient pharmacy database and matched with each case. Primary outcomes included serious complication, any complication, any infection, or surgical site infection. Secondary outcomes included 30-day mortality, length of stay, and Clostridioides difficile infection.

RESULTS

Of 21,112 eligible patients, 2885 (13.7%) were exposed to antibiotics within 90 days prior to surgery with a duration of 7 (IQR: 5-10) days and prescribed 42 (IQR: 21-64) days prior to surgical intervention. Compared to non-exposed patients, exposed patients had higher unadjusted complication rates, increased length of stay, and rates of return to the operating. Exposure was independently associated with return to the operating room (OR: 1.39; 99% CI: 1.05-1.84).

CONCLUSIONS

Among Veterans, recent antibiotic exposure within 90 days of elective surgery was associated with a 39% increase in the odds of return to the operating room. Further work is needed to evaluate the effects of antibiotic exposure and dysbiosis on surgical outcomes.

Laparoscopy is associated with decreased all-cause mortality in patients undergoing emergency general surgery procedures in a regional health system

BACKGROUND

The aim of this study was to evaluate the use of laparoscopic surgery for common emergency general surgery (EGS) procedures within an integrated Acute Care Surgery (ACS) network. We hypothesized that laparoscopy would be associated with improved outcomes.

METHODS

Our integrated health care system's EGS registry created from AAST EGS ICD-9 codes was queried from January 2013 to October 2015. Procedures were grouped as laparoscopic or open. Standard descriptive and univariate tests were performed, and a multivariable logistic regression controlling for open status, age, BMI, Charlson Comorbidity Index (CCI), trauma tier, and resuscitation diagnosis was performed. Laparoscopic procedures converted to open were identified and analyzed using concurrent procedure billing codes across episodes of care.

RESULTS

Of 60,604 EGS patients identified over the 33-month period, 7280 (12.0%) had an operation and 6914 (11.4%) included AAST-defined EGS procedures. There were 4813 (69.6%) surgeries performed laparoscopically. Patients undergoing a laparoscopic procedure tended to be younger (45.7 ± 18.0 years vs. 57.2 ± 17.6, p < 0.001) with similar BMI (29.7 ± 9.0 kg/m² vs. 28.8 ± 8.3, p < 0.001). Patients in the laparoscopic group had lower mean CCI score (1.6 ± 2.3 vs. 3.4 ± 3.2, p ≤ 0.0001). On multivariable analysis, open surgery had the highest association with inpatient mortality (OR 8.67, 4.23-17.75, p < 0.0001) and at all time points (30-, 90-day, 1-, 3-year). At all time points, conversion to open was found to be a statistically significant protective factor.

CONCLUSION

Use of laparoscopy in EGS is common and associated with a decreased risk of all-cause mortality at all time points compared to open procedures. Conversion to open was protective at all time points compared to open procedures.

Factors Associated With Prolonged Antibiotic Use in the Setting of Suspected Pneumonia and Negative Bronchoalveolar Lavage Cultures

Background: Diagnostic criterion for pneumonia includes clinical data and bronchoalveolar lavage cultures (BALCx) to identify pathogens. Although ~60% of BALCx are negative, there may be reluctance to discontinue antibiotics, leading to prolonged antibiotic use (PAU). Objective: The purpose of this study is to compare outcomes of subjects with negative BALCx with PAU versus without prolonged antibiotic use (nPAU). Methods: A retrospective cohort study was conducted including subjects admitted to the intensive care unit (ICU), with suspected pneumonia, and negative BALCx. Data were compared based on length of exposure to antibiotics, PAU (antibiotics >4 days) versus nPAU (antibiotics <4 days). Results: A total of 128 subjects were included, 57 in the PAU group and 71 in the nPAU group. Baseline demographics were similar between groups. Severity of illness measured by multiple organ dysfunction scores at time of bronchoalveolar lavage (BAL) collection to final result showed a statistically significant decrease in the PAU group but not in the nPAU group. No differences were found in ICU days, ventilator-free days, or mortality; however, length of stay was longer for PAU (23 vs. 17, p = .04). In the PAU group, there were fewer BALCx results of "no growth" (23% vs. 45%, p = .04), more positive gram stains (83% vs. 60%, p = .01) and more positive non-BALCx (40% vs. 14%, p = .01). In a multivariate analysis, factors associated with PAU were positive BAL gram stains (adjusted odds ratio [aOR] 3.1, p = .037) and positive non-BALCx (aOR 4.7, p = .002). Conclusion: For subjects with suspected pneumonia and negative BALCx, positive non-BALCx and positive BALCx gram stain influenced the length of exposure of antibiotics.

Emergency General Surgery Regionalization: Retrospective Cohort Study of Emergency General Surgery Patients at a Tertiary Care Center

BACKGROUND

Emergency general surgery (EGS) patients presenting at tertiary care hospitals may bypass local hospitals with adequate resources. However, many tertiary care hospitals frequently operate at capacity. We hypothesized that understanding patient geographic origin could identify opportunities for enhanced system triage and optimization and be an important first step for EGS regionalization and care coordination that could potentially lead to improved utilization of resources.

METHODS

We analyzed patient zip code and categorized EGS patients who were cared for at our tertiary care hospital as potentially divertible if the southern region hospital was geographically closer to their home, regional hospital admission (RHA) patients, or local admission (LA) patients if the tertiary care facility was closer. Baseline characteristics and outcomes were compared for RHA and LA patients.

RESULTS

Of 14 714 EGS patients presenting to the tertiary care hospital, 30.2% were categorized as RHA patients. Overall, 1526 (10.4%) patients required an operation including 527 (34.5%) patients who were potentially divertible. Appendectomy and cholecystectomy comprised 66% of the operations for potentially divertible patients. Length of stay was not significantly different (P = .06) for RHA patients, but they did have lower measured short-term and long-term mortality when compared to their LA counterparts (P < .05).

CONCLUSIONS

EGS diagnoses and patient geocode analysis can identify opportunities to optimize regional operating room and bed utilization. Understanding where EGS patients are cared for and factors that influenced care facility will be critical for next steps in developing EGS regionalization within our system.

Resolution of organ dysfunction as a predictor of long-term survival in necrotizing soft tissue infections: Analysis of the AB103 Clinical Composite Endpoint Study in Necrotizing Soft Tissue Infections trial and a retrospective claims database-linked chart study

BACKGROUND

Necrotizing soft tissue infections (NSTIs) are an acute surgical condition with high morbidity and mortality. Timely identification, resuscitation, and aggressive surgical management have significantly decreased inpatient mortality. However, reduced inpatient mortality has shifted the burden of disease to long-term mortality associated with persistent organ dysfunction.

METHODS

We performed a combined analysis of NSTI patients from the AB103 Clinical Composite Endpoint Study in Necrotizing Soft Tissue Infections randomized-controlled interventional trial (ATB-202) and comprehensive administrative database (ATB-204) to determine the association of persistent organ dysfunction on inpatient and long-term outcomes. Persistent organ dysfunction was defined as a modified Sequential Organ Failure Assessment (mSOFA) score of 2 or greater at Day 14 (D14) after NSTI diagnosis, and resolution of organ dysfunction defined as mSOFA score of 1 or less.

RESULTS

The analysis included 506 hospitalized NSTI patients requiring surgical debridement, including 247 from ATB-202, and 259 from ATB-204. In both study cohorts, age and comorbidity burden were higher in the D14 mSOFA ≥2 group. Patients with D14 mSOFA score of 1 or less had significantly lower 90-day mortality than those with mSOFA score of 2 or higher in both ATB-202 (2.4% vs. 21.5%; p < 0.001) and ATB-204 (6% vs. 16%: p = 0.008) studies. In addition, in an adjusted covariate analysis of the combined study data sets D14 mSOFA score of 1 or lesss was an independent predictor of lower 90-day mortality (odds ratio, 0.26; 95% confidence interval, 0.13-0.53; p = 0.001). In both studies, D14 mSOFA score of 1 or less was associated with more favorable discharge status and decreased resource utilization.

CONCLUSION

For patients with NSTI undergoing surgical management, persistent organ dysfunction at 14 days, strongly predicts higher resource utilization, poor discharge disposition, and higher long-term mortality. Promoting the resolution of acute organ dysfunction after NSTI should be considered as a target for investigational therapies to improve long-term outcomes after NSTI.

LEVEL OF EVIDENCE

Prognostic/epidemiology study, level III.

The Obesity Paradox in Emergency General Surgery Patients

Operative management of emergency general surgery (EGS) diagnoses involves a range of procedures which can carry high morbidity and mortality. Little is known about the impact of obesity on patient outcomes. The aim of this study was to examine the association between body mass index (BMI) >30 kg/m² and mortality for EGS patients. We hypothesized that obese patients would have increased mortality rates.

A regional integrated health system EGS registry derived from The American Association for the Surgery of Trauma EGS ICD-9 codes was analyzed from January 2013 to October 2015. Patients were stratified into BMI categories based on WHO classifications. The primary outcome was 30-day mortality. Longer-term mortality with linkage to the Social Security Death Index was also examined. Univariate and multivariable analyses were performed.

A total of 60 604 encounters were identified and 7183 (11.9%) underwent operative intervention. Patient characteristics include 53% women, mean age 58.2 ± 18.7 years, 64.2% >BMI 30 kg/m², 30.2% with chronic obstructive pulmonary disease, 19% with congestive heart failure, and 31.1% with diabetes. The most common procedure was laparoscopic cholecystectomy (36.4%). Overall, 90-day mortality was 10.9%. In multivariable analysis, all classes of obesity were protective against mortality compared to normal BMI. Underweight patients had increased risk of inpatient (OR = 1.9, CI = 1.7-2.3), 30-day (OR = 1.9, CI = 1.7-2.1), 90-day (OR = 1.8, CI 1.6-2.0), 1-year (OR = 1.8, CI = 1.7-2.0), and 3-year mortality (OR = 1.7, CI = 1.6-1.9).

When stratified by BMI, underweight EGS patients have the highest odds of death. Paradoxically, obesity appears protective against death, even when controlling for potentially confounding factors. Increased rates of nonoperative management in the obese population may impact these findings.

Readmission After Emergency General Surgery: NSQIP Review of Risk, Cause and Ideal Follow-Up

BACKGROUND

The Emergency General Surgery (EGS) population is particularly at high risk for readmission. Currently, no system exists to predict which EGS patients are most at risk. We hypothesized that a subset of EGS patients could be identified with increased 30-day unplanned readmission. We also hypothesized that a majority of readmissions occur sooner than the conventional 2-week follow-up period.

METHODS

National Surgical Quality Improvement Program (NSQIP) nonelective general surgery patients were analyzed. Multivariable logistic regression identified factors with increased odds of unplanned readmission. AAST EGS Diagnosis Categories were used to categorize postop ICD-9 codes, and the top 10 CPT codes in each group were analyzed. Readmission rate, the reason for unplanned readmission, and time to readmission were analyzed.

RESULTS

A total of 383,726 patients were identified with a readmission rate of 8.1% within 30 d of their primary procedure. The top 50 CPT codes accounted for 84% of EGS readmissions. Increased readmission risk was demonstrated for underweight patients (OR = 1.15, P < 0.05). High-risk hospital characteristics were LOS >2 d, any inpatient pulmonary complications, and discharge to any facility or rehab (all P < 0.05). Surgical site infections cause nearly 25% of readmissions. Intestinal procedures are most frequently readmitted (22% of EGS readmissions), with colorectal procedures having the higher odds of readmission. Most readmissions occur <10 d after discharge.

CONCLUSIONS

A high-risk subpopulation exists within EGS, and most readmissions occur sooner than a typical 2-week follow-up. Early interventions for high-risk EGS subpopulations may allow for early intervention and reduction of unnecessary healthcare utilization.

Antibiotic Exposure Is Not Associated With Clearance of Bronchoalveolar Growth: Results From a Prospective Ventilator-Associated Pneumonia Study

BACKGROUND

Ventilator-associated pneumonia is poorly understood in trauma. Ventilated trauma patients can develop bacterial burden without symptoms; the factors that influence this are unknown.

METHODS

Injured adults ventilated for > 2 days were enrolled. Mini-bronchoalveolar lavage was performed for 14 days or until extubation. Semi-quantitative cultures were blinded from clinicians. All cultures with > 104 colony forming units (CFU) were assessed for antibiotic exposure (ABXE) and spectrum of coverage. mBAL CFU was assessed daily.

RESULTS

60 patients were ventilated for 9 days (median). There were 75 with > 104 CFU. 46 had > 104 CFU and no ABXE on the sample day. 74% had clearance or a decrease (CoD) in CFU without ABXE. 29 had > 104 CFU and ABXE on the sample day. 19 had ABXE with pathogen coverage. 84% had CoD in CFU. 10 had ABXE with no spectrum of coverage. 1/10 had increased CFU and the remaining 9/10 CoD in CFU. The three groups were not statistically different on chi-squared analysis.

CONCLUSION

Clearance of pathogens on surveillance cultures was unaffected by ABXE.

Estimating the Impact of Necrotizing Soft Tissue Infections in the United States: Incidence and Re-Admissions

Background: Previous estimates of the incidence of necrotizing soft tissue infections (NSTI) in the United States have substantial limitations and underestimate its occurrence. Improvements in hospital mortality after NSTI have increased the number of survivors at risk for long-term sequelae. This study estimates the incidence of NSTI and the burden of re-admission and associated healthcare spending in patients who survived admission for NSTI. Methods: Index admissions for NSTI were identified using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes combined with either Current Procedural Technology (CPT) or diagnosis-related group codes to increase specificity. Two separate datasets were used to provide primary and secondary estimates of the annual incidence of NSTIs in the United States: the National Inpatient Sample (NIS) for the years 2012-2016 and the Watson Health dataset for 2009-2013, respectively, and extrapolated to estimate the incidence for 2018. The Nationwide Readmissions Database (NRD) from 2013-2015 was used to estimate of the risk for re-admission, cost of re-admissions, and to compare 90-day re-admission rates for NSTI to common medical conditions. Results: National Inpatient Sample and Watson Health datasets demonstrated an increasing annual incidence and estimated 33,600 and 28,500 cases in 2018, respectively. The estimated annual incidences in the United States in 2018 were 10.3 and 8.7 per 100,000 persons, respectively. Risk of 90-day re-admission ranged from 24%-29% over the 3 years, 89% of which were unplanned. Of those re-admitted, 90% had one or more comorbidities, the most common diagnoses associated with re-admission were infection in 65%, acute kidney injury in 22%, and shock in 10%. The median re-admission length of stay was seven days (interquartile range [IQR]: 4-13 days) with a median cost of re-admission of $13,590 (IQR: $7186-$27440). Conclusion: The incidence of NSTI is more common than generally reported. Re-admission within 90 days is common, occurring in more than one in four survivors resulting in high healthcare costs.

Pro-Con Perspectives on Ethics in Surgical Research: Update from the 39th Annual Surgical Infection Society Meeting

Background: Surgical research is potentially invasive, high-risk, and costly. Research that advances medical dogma must justify both its ends and its means. Although ethical questions do not always have simple answers, it is critically important for the clinician, researcher, and patient to approach these dilemmas and surgical research in a thoughtful, conscientious manner. Methods: We present four ethical issues in surgical research and discuss the opposing viewpoints. These topics were presented and discussed at the 39th Annual Meeting of the Surgical Infection Society as pro-con debates. The presenters of each opinion developed a succinct summary of their respective reviews for this publication. Results: The key subjects for these pro-con debates were: (1) Should patients be enrolled for time-sensitive surgical infection research using an opt-out or an opt-in strategy? (2) Should patients who are being enrolled in a randomized controlled trial (RCT) comparing surgery with a non-operative intervention pay the costs of their treatment arm? (3) Should the scientific community embrace open access journals as the future of scientific publishing? (4) Should the majority of funding go to clinical or basic science research? Important points were illustrated in each of the pro-con presentations and illustrated the difficulties that are facing the performance and payment of infection research in the future. Conclusions: Surgical research is ethically complex, with conflicting demands between individual patients, society, and healthcare economics. At present, there are no clear answers to these and the many other ethical issues facing research in the future. Answers will only come from continued robust dialogue among all stakeholders in surgical research.

Maximizing the Calm before the Storm: Tiered Surgical Response Plan for Novel Coronavirus (COVID-19)

The novel coronavirus (COVID-19) was first diagnosed in Wuhan, China in December 2019 and has now spread throughout the world, being verified by the World Health Organization as a pandemic on March 11. This had led to the calling of a national emergency on March 13 in the US. Many hospitals, healthcare networks, and specifically, departments of surgery, are asking the same questions about how to cope and plan for surge capacity, personnel attrition, novel infrastructure utilization, and resource exhaustion. Herein, we present a tiered plan for surgical department planning based on incident command levels. This includes acute care surgeon deployment (given their critical care training and vertically integrated position in the hospital), recommended infrastructure and transfer utilization, triage principles, and faculty, resident, and advanced care practitioner deployment.

Role of heat shock protein and cytokine expression as markers of clinical outcomes with glutamine-supplemented parenteral nutrition in surgical ICU patients

BACKGROUND

Nutrients, such as glutamine (GLN), have been shown to effect levels of a family of protective proteins termed heat shock proteins (HSPs) in experimental and clinical critical illness. HSPs are believed to serve as extracellular inflammatory messengers and intracellular cytoprotective molecules. Extracellular HSP70 (eHSP70) has been termed a chaperokine due to ability to modulate the immune response. Altered levels of eHSP70 are associated with various disease states. Larger clinical trial data on GLN effect on eHSP expression and eHSP70's association with inflammatory mediators and clinical outcomes in critical illness are limited.

OBJECTIVE

Explore effect of longitudinal change in serum eHSP70, eHSP27 and inflammatory cytokine levels on clinical outcomes such as pneumonia and mortality in adult surgical intensive care unit (SICU) patients. Further, evaluate effect of parenteral nutrition (PN) supplemented with GLN (GLN-PN) versus GLN-free, standard PN (STD-PN) on serum eHSP70 and eHSP27 concentrations.

METHODS

Secondary observational analysis of a multicenter clinical trial in 150 adults after cardiac, vascular, or gastrointestinal surgery requiring PN support and SICU care conducted at five academic medical centers. Patients received isocaloric, isonitrogenous PN, with or without GLN dipeptide. Serum eHSP70 and eHSP27, interleukin-6 (IL-6), and 8 (IL-8) concentrations were analyzed in patient serum at baseline (prior to study PN) and over 28 days of follow up.

RESULTS

eHSP70 declined over time in survivors during 28 days follow-up, but non-survivors had significantly higher eHSP70 concentrations compared to survivors. In patients developing pneumonia, eHSP70, eHSP27, IL-8, and IL-6 were significantly elevated. Adjusted relative risk for hospital mortality was reduced 75% (RR = 0.25, p = 0.001) for SICU patients with a faster decline in eHSP70. The area under the receiver operating characteristic curve was 0.85 (95% CI: 0.76 to 0.94) for the final model suggesting excellent discrimination between SICU survivors and non-survivors. GLN-PN did not alter eHSP70 or eHSP27 serum concentrations over time compared to STD-PN.

CONCLUSION

Our results suggest that serum HSP70 concentration may be an important marker for severity of illness and likelihood of recovery in the SICU. GLN-supplemented-PN did not increase eHSP70.

Knowledge, awareness, and attitude towards infection prevention and management among surgeons: identifying the surgeon champion

Despite evidence supporting the effectiveness of best practices of infection prevention and management, many surgeons worldwide fail to implement them. Evidence-based practices tend to be underused in routine practice. Surgeons with knowledge in surgical infections should provide feedback to prescribers and integrate best practices among surgeons and implement changes within their team. Identifying a local opinion leader to serve as a champion within the surgical department may be important. The “surgeon champion” can integrate best clinical practices of infection prevention and management, drive behavior change in their colleagues, and interact with both infection control teams in promoting antimicrobial stewardship.

Bacterial Burden in Critically Injured Ventilated Patients Does Not Correlate with Progression to Pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) is common in critically injured patients. The pathogenesis of VAP is not completely understood. We hypothesized that mechanically ventilated trauma patients who develop pneumonia have a progressive increase in pathogen burden over the course of ventilation until a threshold for symptomatic pneumonia is reached, leading to clinical suspicion of VAP.

METHODS

Critically injured adults ventilated for more than two successive days were enrolled. Patients underwent daily surveillance mini-bronchoscopic alveolar lavage (mBAL) while ventilated for 14 days or until extubation. Standard semi-quantitative cultures were performed, and the investigators were blinded to the results. Standard patient management was performed by the clinical team. Patients suspected of having VAP by the clinical team underwent bronchoscopic bronchoalveolar lavage (bBAL) and semi-quantitative culture, with VAP defined as clinical symptoms plus >10⁴ colony-forming units (CFU) of bacteria. Standard statistical analysis for non-parametric data was performed.

RESULTS

The 37 patients enrolled were ventilated for a median of nine days. While ventilated, 23 patients met the criteria for a clinical suspicion of VAP, of which two were too ill for bronchoscopy. Thus, 21 patients underwent bBALs because of a suspicion of VAP, and 13 (35%) were positive, with >10⁴ CFU of one or more pathogens, and were treated for pneumonia. The bacterial burden on mBAL remained <10⁴ CFU during ventilation for 32% of patients. None developed clinical symptoms of VAP. Two-thirds (67%) had an mBAL bacterial burden of >10⁴ CFU without clinical suspicion of VAP. Half (56%) of positive surveillance cultures were followed by clinical VAP, confirmed by bBAL, all of which had identical pathogens on mBAL and bBAL. Almost half (44%) of the patients with positive surveillance mBALs never developed clinical VAP.

CONCLUSION

A significant percentage of critically injured, ventilated adults develop high bacterial burdens in the lungs early in their course, and many clear these bacteria without developing VAP. Further study is needed to identify the factors causing progression to VAP.

Balanced Crystalloids versus Saline in Critically Ill Adults

BACKGROUND

Both balanced crystalloids and saline are used for intravenous fluid administration in critically ill adults, but it is not known which results in better clinical outcomes.

METHODS

In a pragmatic, cluster-randomized, multiple-crossover trial conducted in five intensive care units at an academic center, we assigned 15,802 adults to receive saline (0.9% sodium chloride) or balanced crystalloids (lactated Ringer's solution or Plasma-Lyte A) according to the randomization of the unit to which they were admitted. The primary outcome was a major adverse kidney event within 30 days - a composite of death from any cause, new renal-replacement therapy, or persistent renal dysfunction (defined as an elevation of the creatinine level to ≥200% of baseline) - all censored at hospital discharge or 30 days, whichever occurred first.

RESULTS

Among the 7942 patients in the balanced-crystalloids group, 1139 (14.3%) had a major adverse kidney event, as compared with 1211 of 7860 patients (15.4%) in the saline group (marginal odds ratio, 0.91; 95% confidence interval [CI], 0.84 to 0.99; conditional odds ratio, 0.90; 95% CI, 0.82 to 0.99; P=0.04). In-hospital mortality at 30 days was 10.3% in the balanced-crystalloids group and 11.1% in the saline group (P=0.06). The incidence of new renal-replacement therapy was 2.5% and 2.9%, respectively (P=0.08), and the incidence of persistent renal dysfunction was 6.4% and 6.6%, respectively (P=0.60).

CONCLUSIONS

Among critically ill adults, the use of balanced crystalloids for intravenous fluid administration resulted in a lower rate of the composite outcome of death from any cause, new renal-replacement therapy, or persistent renal dysfunction than the use of saline. (Funded by the Vanderbilt Institute for Clinical and Translational Research and others; SMART-MED and SMART-SURG ClinicalTrials.gov numbers, NCT02444988 and NCT02547779 .).

A Global Declaration on Appropriate Use of Antimicrobial Agents across the Surgical Pathway

This declaration, signed by an interdisciplinary task force of 234 experts from 83 different countries with different backgrounds, highlights the threat posed by antimicrobial resistance and the need for appropriate use of antibiotic agents and antifungal agents in hospitals worldwide especially focusing on surgical infections. As such, it is our intent to raise awareness among healthcare workers and improve antimicrobial prescribing. To facilitate its dissemination, the declaration was translated in different languages.

Evaluation of a Short Course of Antimicrobial Therapy for Complicated Intra-Abdominal Infections in Critically Ill Surgical Patients

BACKGROUND

The optimal duration of antimicrobial therapy for treatment of complicated intra-abdominal infections (cIAI) in critically ill surgical patients is unknown. Recent evidence suggests that a short (four-day) course of therapy may be effective, however data in severely critically ill patients are limited.

PATIENTS AND METHODS

A single-center, retrospective, cohort study was conducted at a tertiary academic medical center. Adult patients admitted to the surgical intensive care unit (SICU) with cIAI between December 2011 and July 2015 were enrolled. Patients undergoing transplantation and those with less than 24 h in the SICU were excluded. Patients were divided into two groups, short (≤ 7 d) and long (> 7 d) antimicrobial therapy. The primary outcome was treatment failure, which was defined as a composite of recurrent cIAI, secondary extra-abdominal infection, and/or in-hospital mortality from any cause. Categorical and continuous data were analyzed with χ² and Mann-Whitney U tests, respectively. Binary logistic regression was performed to determine factors associated with treatment failure and mortality.

RESULTS

Of 1,679 patients screened, 240 were included, 103 in the short and 137 in the long group. Patients in the short and long groups received a median of 5 and 14 d of therapy, respectively (p < 0.001). Treatment failure occurred less frequently with a short duration of therapy (39% versus 63%, p < 0.001) and it occurred two days sooner after source control in patients receiving the shorter courses of antimicrobial therapy (short, median 6 d, interquartile range [IQR] 3-9; long, 8 d, IQR 6-14; p < 0.001). Logistic regression demonstrated that a long duration of therapy was associated with treatment failure (odds ratio [OR] 2.186, 95% confidence interval [CI] 1.251-3.820, p = 0.006), but not with mortality (OR 0.738, 95% CI 0.329-1.655, p = 0.461).

CONCLUSIONS

In critically ill surgical patients with cIAI, a short duration of antimicrobial therapy after source control resulted in similar outcomes to previously published studies, providing support for the safety of this approach in critically ill patients.

Endothelial glycocalyx degradation is more severe in patients with non-pulmonary sepsis compared to pulmonary sepsis and associates with risk of ARDS and other organ dysfunction

BACKGROUND

Disruption of the endothelial glycocalyx contributes to acute lung injury in experimental sepsis but has not been well studied in humans. To study glycocalyx degradation in sepsis-induced ARDS, we measured plasma levels of syndecan-1, a marker for glycocalyx degradation.

METHODS

The present study is a retrospective observational study of 262 ventilated medical ICU patients at risk of ARDS due to severe sepsis and APACHE II ≥ 25. Plasma syndecan-1 was measured at study enrollment. Primary analysis focused on the association between syndecan-1 levels and the development of ARDS, other organ dysfunction (Brussels criteria), or in-hospital mortality.

RESULTS

Overall, 135 (52%) patients developed ARDS. In patients with non-pulmonary sepsis, syndecan-1 levels were associated with ARDS (p = 0.05). Regardless of etiology of sepsis, higher syndecan-1 levels were associated with hepatic (p < 0.001), renal (p = 0.003), coagulation (p = 0.001), and circulatory (p = 0.02) failure as well as in-hospital mortality (p = 0.001), and there was a significant association between syndecan-1 levels and the number of vasopressors required in the first 24 h (p < 0.001). In addition, elevated syndecan levels were independently predictive of mortality in multivariable logistic regression adjusted for age and APACHE II score (odds ratio 1.85 per log increase in syndecan-1, 95% CI 1.056-3.241, p = 0.03).

CONCLUSION

The extent of endothelial glycocalyx degradation is associated with non-pulmonary organ dysfunction in subjects with sepsis and is associated with ARDS but only in the subgroup with non-pulmonary sepsis. Measurement of syndecan-1 levels in sepsis patients might be useful for identifying patients at high risk of organ dysfunction and mortality as well as those who could benefit from therapies targeted at protecting or restoring the glycocalyx.

Sepsis and Septic Shock Strategies

Three therapeutic principles most substantially improve organ dysfunction and survival in sepsis: early, appropriate antimicrobial therapy; restoration of adequate cellular perfusion; timely source control. The new definitions of sepsis and septic shock reflect the inadequate sensitivity, specify, and lack of prognostication of systemic inflammatory response syndrome criteria. Sequential (sepsis-related) organ failure assessment more effectively prognosticates in sepsis and critical illness. Inadequate cellular perfusion accelerates injury and reestablishing perfusion limits injury. Multiple organ systems are affected by sepsis and septic shock and an evidence-based multipronged approach to systems-based therapy in critical illness results in improve outcomes.

Creating a Global Acute Care Surgery Fellowship to Meet International Need

INTRODUCTION

Existing Acute Care Surgery (ACS) fellowships are positioned to develop well-trained surgeons with specific skills to facilitate improvements in care delivery in Global ACS. Many resident and fellowship programs offer clinical electives that expose trainees to operative experiences, exposing trainees to the needs in resource-challenged settings. However, most lack a focus on long-term development and research designed to enhance the country's local skills, capability, and capacity. The Global Acute Care Surgery (Global ACS) fellowship produces a surgeon who focuses on capacity building and systems development across the world.

METHODS

At Vanderbilt University, the current American Association for the Surgery of Trauma-Acute Care Surgery (AAST-ACS) fellowship was adapted to create an academic Global Acute Care Surgery (Global ACS) fellowship. This fellowship specifically enhances fellowship trainee's skills in needs assessment and performing research to facilitate the development and implementation of trauma and acute care surgery systems in low- and middle income countries. This research will foster context-appropriate data, collected and based in low- and middle-income countries, to guide practice and policy.

RESULTS AND CONCLUSION

Two fellows have completed the Global ACS fellowship at Vanderbilt University. The fellowship requirements, clinical skills, project development and overall goals are outlined within the article. Challenges, funding, and mentorship must also be addressed to develop a comprehensive fellowship. A sample two-year timeline is provided to complete the fellowship track and meet the defined goals. A structured global acute care surgery fellowship enables fellows to reduce the surgical burden of disease and contribute to surgical systems development at both local and international levels by creating meaningful research and developing sustainable change in LMIC countries.

Derivation and validation of a two-biomarker panel for diagnosis of ARDS in patients with severe traumatic injuries

Background

Acute respiratory distress syndrome (ARDS) is common after severe traumatic injuries but is underdiagnosed and undertreated. We hypothesized that a panel of plasma biomarkers could be used to diagnose ARDS in severe trauma. To test this hypothesis, we derived and validated a biomarker panel in three independent cohorts and compared the diagnostic performance to clinician recognition of ARDS.

Methods

Eleven plasma biomarkers of inflammation, lung epithelial and endothelial injury were measured in a derivation cohort of 439 severe trauma patients. ARDS status was analyzed by two-investigator consensus, and cases were required to meet Berlin criteria on intensive care unit (ICU) day 1. Controls were subjects without ARDS during the first 4 days of study enrollment. A multivariable logistic regression model was used to generate probabilities for ARDS. A reduced model with the top two performing markers was then tested in two independent validation cohorts. To assess clinical diagnosis of ARDS, medical records in the derivation cohort were systematically searched for documentation of ARDS diagnosis made by a clinical provider.

Results

Among 11 biomarkers, the combination of the endothelial injury marker angiopoietin-2 (Ang-2) and the lung epithelial injury marker receptor for advanced glycation endproducts (RAGE) provided good discrimination for ARDS in the derivation cohort (area under the curve (AUC)=0.74 (95% CI 0.67 to 0.80). In the validation cohorts, the AUCs for this model were 0.70 (0.61 to 0.77) and 0.78 (0.71 to 0.84). In contrast, provider assessment demonstrated poor diagnostic accuracy for ARDS, with AUC of 0.55 (0.51 to 0.60).

Discussion

A two-biomarker panel consisting of Ang-2 and RAGE performed well across multiple patient cohorts and outperformed clinical providers for diagnosing ARDS in severe trauma. Clinical application of this model could improve both diagnosis and treatment of ARDS in patients with severe trauma.

Level of evidence

Diagnostic study, level II.

The role of open abdomen in non-trauma patient: WSES Consensus Paper

The open abdomen (OA) is defined as intentional decision to leave the fascial edges of the abdomen un-approximated after laparotomy (laparostomy). The abdominal contents are potentially exposed and therefore must be protected with a temporary coverage, which is referred to as temporal abdominal closure (TAC). OA use remains widely debated with many specific details deserving detailed assessment and clarification. To date, in patients with intra-abdominal emergencies, the OA has not been formally endorsed for routine utilization; although, utilization is seemingly increasing. Therefore, the World Society of Emergency Surgery (WSES), Abdominal Compartment Society (WSACS) and the Donegal Research Academy united a worldwide group of experts in an international consensus conference to review and thereafter propose the basis for evidence-directed utilization of OA management in non-trauma emergency surgery and critically ill patients. In addition to utilization recommendations, questions with insufficient evidence urgently requiring future study were identified.

External validation of a biomarker and clinical prediction model for hospital mortality in acute respiratory distress syndrome

PURPOSE

Mortality prediction in ARDS is important for prognostication and risk stratification. However, no prediction models have been independently validated. A combination of two biomarkers with age and APACHE III was superior in predicting mortality in the NHLBI ARDSNet ALVEOLI trial. We validated this prediction tool in two clinical trials and an observational cohort.

METHODS

The validation cohorts included 849 patients from the NHLBI ARDSNet Fluid and Catheter Treatment Trial (FACTT), 144 patients from a clinical trial of sivelestat for ARDS (STRIVE), and 545 ARDS patients from the VALID observational cohort study. To evaluate the performance of the prediction model, the area under the receiver operating characteristic curve (AUC), model discrimination, and calibration were assessed, and recalibration methods were applied.

RESULTS

The biomarker/clinical prediction model performed well in all cohorts. Performance was better in the clinical trials with an AUC of 0.74 (95% CI 0.70-0.79) in FACTT, compared to 0.72 (95% CI 0.67-0.77) in VALID, a more heterogeneous observational cohort. The AUC was 0.73 (95% CI 0.70-0.76) when FACTT and VALID were combined.

CONCLUSION

We validated a mortality prediction model for ARDS that includes age, APACHE III, surfactant protein D, and interleukin-8 in a variety of clinical settings. Although the model performance as measured by AUC was lower than in the original model derivation cohort, the biomarker/clinical model still performed well and may be useful for risk assessment for clinical trial enrollment, an issue of increasing importance as ARDS mortality declines, and better methods are needed for selection of the most severely ill patients for inclusion.

The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection

BACKGROUND

Previous evidence-based guidelines on the management of intra-abdominal infection (IAI) were published by the Surgical Infection Society (SIS) in 1992, 2002, and 2010. At the time the most recent guideline was released, the plan was to update the guideline every five years to ensure the timeliness and appropriateness of the recommendations.

METHODS

Based on the previous guidelines, the task force outlined a number of topics related to the treatment of patients with IAI and then developed key questions on these various topics. All questions were approached using general and specific literature searches, focusing on articles and other information published since 2008. These publications and additional materials published before 2008 were reviewed by the task force as a whole or by individual subgroups as to relevance to individual questions. Recommendations were developed by a process of iterative consensus, with all task force members voting to accept or reject each recommendation. Grading was based on the GRADE (Grades of Recommendation Assessment, Development, and Evaluation) system; the quality of the evidence was graded as high, moderate, or weak, and the strength of the recommendation was graded as strong or weak. Review of the document was performed by members of the SIS who were not on the task force. After responses were made to all critiques, the document was approved as an official guideline of the SIS by the Executive Council.

RESULTS

This guideline summarizes the current recommendations developed by the task force on the treatment of patients who have IAI. Evidence-based recommendations have been made regarding risk assessment in individual patients; source control; the timing, selection, and duration of antimicrobial therapy; and suggested approaches to patients who fail initial therapy. Additional recommendations related to the treatment of pediatric patients with IAI have been included.

SUMMARY

The current recommendations of the SIS regarding the treatment of patients with IAI are provided in this guideline.

Management of intra-abdominal infections: recommendations by the WSES 2016 consensus conference

This paper reports on the consensus conference on the management of intra-abdominal infections (IAIs) which was held on July 23, 2016, in Dublin, Ireland, as a part of the annual World Society of Emergency Surgery (WSES) meeting. This document covers all aspects of the management of IAIs. The Grading of Recommendations Assessment, Development and Evaluation recommendation is used, and this document represents the executive summary of the consensus conference findings.

Balanced crystalloids versus saline in the intensive care unit: study protocol for a cluster-randomized, multiple-crossover trial

Background

Saline, the intravenous fluid most commonly administered to critically ill adults, contains a high chloride content, which may be associated with acute kidney injury and death. Whether using balanced crystalloids rather than saline decreases the risk of acute kidney injury and death among critically ill adults remains unknown.

Methods

The Isotonic Solutions and Major Adverse Renal Events Trial (SMART) is a pragmatic, cluster-level allocation, cluster-level crossover trial being conducted between 1 June 2015 and 30 April 2017 in five intensive care units at Vanderbilt University Medical Center in Nashville, TN, USA. SMART compares saline (0.9% sodium chloride) with balanced crystalloids (clinician’s choice of lactated Ringer’s solution or Plasma-Lyte A®). Each intensive care unit is assigned to provide either saline or balanced crystalloids each month, with the assigned crystalloid alternating monthly over the course of the trial. All adults admitted to participating intensive care units during the study period are enrolled and followed until hospital discharge or 30 days after enrollment. The anticipated enrollment is approximately 14,000 patients. The primary outcome is Major Adverse Kidney Events within 30 days—the composite of in-hospital death, receipt of new renal replacement therapy, or persistent renal dysfunction (discharge creatinine ≥200% of baseline creatinine). Secondary clinical outcomes include in-hospital mortality, intensive care unit-free days, ventilator-free days, vasopressor-free days, and renal replacement therapy-free days. Secondary renal outcomes include new renal replacement therapy receipt, persistent renal dysfunction, and incidence of stage 2 or higher acute kidney injury.

Discussion

This ongoing pragmatic trial will provide the largest and most comprehensive comparison to date of clinical outcomes with saline versus balanced crystalloids among critically ill adults.

Trial registration

For logistical reasons, SMART was prospectively registered separately for the medical ICU (SMART-MED; ClinicalTrials.gov identifier: NCT02444988; registered on 11 May 2015; date of first patient enrollment: 1 June 2015) and the nonmedical ICUs (SMART-SURG; ClinicalTrials.gov identifier: NCT02547779; registered on 9 September 2015; date of first patient enrollment: 1 October 2015).

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1871-1) contains supplementary material, which is available to authorized users.

Early exposure to hyperoxia and mortality in critically ill patients with severe traumatic injuries

BACKGROUND

Hyperoxia is common early in the course of resuscitation of critically ill patients. It has been associated with mortality in some, but not all, studies of cardiac arrest patients and other critically ill cohorts. Reasons for the inconsistency are unclear and may depend on unmeasured patient confounders, the timing and duration of hyperoxia, population characteristics, or the way that hyperoxia is defined and measured. We sought to determine whether, in a prospectively collected cohort of mechanically ventilated patients with traumatic injuries with and without head trauma, higher maximum partial pressure of arterial oxygen (PaO2) within 24 hours of admission would be associated with increased risk of in-hospital mortality.

METHODS

Critically ill patients with traumatic injuries undergoing invasive mechanical ventilation enrolled in the Validating Acute Lung Injury biomarkers for Diagnosis (VALID) study were included in this study. All arterial blood gases (ABGs) from the first 24 hours of admission were recorded. Primary analysis was comparison of the highest PaO2 between hospital survivors and non-survivors.

RESULTS

A total of 653 patients were evaluated for inclusion. Of these, 182 were not mechanically ventilated or did not have an ABG measured in the first 24 hours, leaving 471 patients in the primary analysis. In survivors, the maximum PaO2 was 141 mmHg (median, interquartile range 103 - 212) compared to 148 mmHg (IQR 105 - 209) in non-survivors (p = 0.82). In the subgroup with head trauma (n = 266), the maximum PaO2 was 133 mmHg (IQR 97 - 187) among survivors and 152 mmHg (108 - 229) among nonsurvivors (p = 0.19). After controlling for age, injury severity score, number of arterial blood gases, and fraction of inspired oxygen, maximum PaO2 was not associated with increased mortality (OR 1.27 for every fold increase of PaO2 (95% CI 0.72 - 2.25).

CONCLUSIONS

In mechanically ventilated patients with severe traumatic injuries, hyperoxia in the first 24 hours of admission was not associated with increased risk of death or worsened neurological outcomes in a setting without brain tissue oxygenation monitoring.

The Global Alliance for Infections in Surgery: defining a model for antimicrobial stewardship-results from an international cross-sectional survey

BACKGROUND

Antimicrobial Stewardship Programs (ASPs) have been promoted to optimize antimicrobial usage and patient outcomes, and to reduce the emergence of antimicrobial-resistant organisms. However, the best strategies for an ASP are not definitively established and are likely to vary based on local culture, policy, and routine clinical practice, and probably limited resources in middle-income countries. The aim of this study is to evaluate structures and resources of antimicrobial stewardship teams (ASTs) in surgical departments from different regions of the world.

METHODS

A cross-sectional web-based survey was conducted in 2016 on 173 physicians who participated in the AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections) project and on 658 international experts in the fields of ASPs, infection control, and infections in surgery.

RESULTS

The response rate was 19.4%. One hundred fifty-six (98.7%) participants stated their hospital had a multidisciplinary AST. The median number of physicians working inside the team was five [interquartile range 4-6]. An infectious disease specialist, a microbiologist and an infection control specialist were, respectively, present in 80.1, 76.3, and 67.9% of the ASTs. A surgeon was a component in 59.0% of cases and was significantly more likely to be present in university hospitals (89.5%, p < 0.05) compared to community teaching (83.3%) and community hospitals (66.7%). Protocols for pre-operative prophylaxis and for antimicrobial treatment of surgical infections were respectively implemented in 96.2 and 82.3% of the hospitals. The majority of the surgical departments implemented both persuasive and restrictive interventions (72.8%). The most common types of interventions in surgical departments were dissemination of educational materials (62.5%), expert approval (61.0%), audit and feedback (55.1%), educational outreach (53.7%), and compulsory order forms (51.5%).

CONCLUSION

The survey showed a heterogeneous organization of ASPs worldwide, demonstrating the necessity of a multidisciplinary and collaborative approach in the battle against antimicrobial resistance in surgical infections, and the importance of educational efforts towards this goal.

Antimicrobial Stewardship: A Call to Action for Surgeons

Despite current antimicrobial stewardship programs (ASPs) being advocated by infectious disease specialists and discussed by national and international policy makers, ASPs coverage remains limited to only certain hospitals as well as specific service lines within hospitals. The ASPs incorporate a variety of strategies to optimize antimicrobial agent use in the hospital, yet the exact set of interventions essential to ASP success remains unknown. Promotion of ASPs across clinical practice is crucial to their success to ensure standardization of antimicrobial agent use within an institution. To effectively accomplish this standardization, providers who actively engage in antimicrobial agent prescribing should participate in the establishment and support of these programs. Hence, surgeons need to play a major role in these collaborations. Surgeons must be aware that judicious antibiotic utilization is an integral part of any stewardship program and necessary to maximize clinical cure and minimize emergence of antimicrobial resistance. The battle against antibiotic resistance should be fought by all healthcare professionals. If surgeons around the world participate in this global fight and demonstrate awareness of the major problem of antimicrobial resistance, they will be pivotal leaders. If surgeons fail to actively engage and use antibiotics judiciously, they will find themselves deprived of the autonomy to treat their patients.

A surgeon's guide to anticoagulant and antiplatelet medications part one: warfarin and new direct oral anticoagulant medications

An increasing number of potent antiplatelet and anticoagulant medications are being used for the long-term management of cardiac, cerebrovascular, and peripheral vascular conditions. Management of these medications in the perioperative and peri-injury settings can be challenging for surgeons, mandating an understanding of these agents and the risks and benefits of various management strategies. In this two-part review, agents commonly encounter by surgeons in the perioperative and peri-injury settings are discussed and management strategies for patients on long-term antiplatelet and anticoagulant therapy reviewed. In part I, we review warfarin and the new direct oral anticoagulants. In part II, we review antiplatelet agents and assessment of platelet function and the perioperative management of long-term anticoagulant and antiplatelet therapy.

Surgeon's guide to anticoagulant and antiplatelet medications part two: antiplatelet agents and perioperative management of long-term anticoagulation

An increasing number of potent antiplatelet and anticoagulant medications are being used for the long-term management of cardiac, cerebrovascular, and peripheral vascular conditions. Management of these medications in the perioperative and peri-injury settings can be challenging for surgeons, mandating an understanding of these agents and the risks and benefits of various management strategies. In this two part review, agents commonly encountered by surgeons in the perioperative and peri-injury settings are discussed and management strategies for patients on long-term antiplatelet and anticoagulant therapy reviewed. In part one, we review warfarin and the new direct oral anticoagulants. In part two, we review antiplatelet agents and assessment of platelet function and the perioperative management of long-term anticoagulation and antiplatelet therapy.

Long-Term Ozone Exposure Increases the Risk of Developing the Acute Respiratory Distress Syndrome

RATIONALE

The contribution of air pollution to the risk of acute respiratory distress syndrome (ARDS) is unknown.

METHODS

We studied 1,558 critically ill patients enrolled in a prospective observational study at a tertiary medical center who lived less than 50 km from an air quality monitor and had an ARDS risk factor. Pollutant exposures (ozone, NO2, SO2, particulate matter < 2.5 μm, particulate matter < 10 μm) were assessed by weighted average of daily levels from the closest monitors for the prior 3 years. Associations between pollutant exposure and ARDS risk were evaluated by logistic regression controlling for age, race, sex, smoking, alcohol, insurance status, rural versus urban residence, distance to study hospital, and Acute Physiology and Chronic Health Evaluation II.

MEASUREMENTS AND MAIN RESULTS

The incidence of ARDS increased with increasing ozone exposure: 28% in the lowest exposure quartile versus 32, 40, and 42% in the second, third, and fourth quartiles (P < 0.001). In a logistic regression model controlling for potential confounders, ozone exposure was associated with risk of ARDS in the entire cohort (odds ratio, 1.58 [95% confidence interval, 1.27-1.96]) and more strongly associated in the subgroup with trauma as their ARDS risk factor (odds ratio, 2.26 [95% confidence interval, 1.46-3.50]). There was a strong interaction between ozone exposure and current smoking status (P = 0.007). NO2 exposure was also associated with ARDS but not independently of ozone exposure. SO2, particulate matter less than 2.5 μm, and particulate matter less than 10 μm were not associated with ARDS.

CONCLUSIONS

Long-term ozone exposure is associated with development of ARDS in at-risk critically ill patients, particularly in trauma patients and current smokers. Ozone exposure may represent a previously unrecognized environmental risk factor for ARDS.

An Argument for the Use of Aminoglycosides in the Empiric Treatment of Ventilator-Associated Pneumonia

BACKGROUND

Appropriate empiric antibiotic therapy for ventilator-associated pneumonia improves outcomes. Controversy exists regarding the inclusion of aminoglycosides in empiric therapeutic regimens.

METHODS

The Ovid and Cochrane databases were searched for relevant literature regarding the use of aminoglycosides in combination therapy for ventilator-associated pneumonia. The data supporting the use of aminoglycosides in certain populations and strategies to limit toxicity are summarized.

RESULTS

In patients at high risk of infection with antibiotic-resistant gram-negative bacilli and in those with severe illness, aminoglycosides improve clinical outcomes. In critically ill populations, short-duration therapy and high-dose extended-interval dosing of aminoglycosides can improve therapeutic efficacy while limiting nephrotoxicity.

CONCLUSIONS

In selected populations using appropriate dosing strategies, aminoglycosides should be considered for empiric treatment of ventilator-associated pneumonia.

Antimicrobials: a global alliance for optimizing their rational use in intra-abdominal infections (AGORA)

Intra-abdominal infections (IAI) are an important cause of morbidity and are frequently associated with poor prognosis, particularly in high-risk patients. The cornerstones in the management of complicated IAIs are timely effective source control with appropriate antimicrobial therapy. Empiric antimicrobial therapy is important in the management of intra-abdominal infections and must be broad enough to cover all likely organisms because inappropriate initial antimicrobial therapy is associated with poor patient outcomes and the development of bacterial resistance. The overuse of antimicrobials is widely accepted as a major driver of some emerging infections (such as C. difficile), the selection of resistant pathogens in individual patients, and for the continued development of antimicrobial resistance globally. The growing emergence of multi-drug resistant organisms and the limited development of new agents available to counteract them have caused an impending crisis with alarming implications, especially with regards to Gram-negative bacteria. An international task force from 79 different countries has joined this project by sharing a document on the rational use of antimicrobials for patients with IAIs. The project has been termed AGORA (Antimicrobials: A Global Alliance for Optimizing their Rational Use in Intra-Abdominal Infections). The authors hope that AGORA, involving many of the world's leading experts, can actively raise awareness in health workers and can improve prescribing behavior in treating IAIs.

Insulin resistance increases before ventilator-associated pneumonia in euglycemic trauma patients

BACKGROUND

Hyperglycemia caused by stress-induced insulin resistance is associated with both infection and mortality in critically injured patients. The onset of infection may increase stress-induced insulin resistance, leading to hyperglycemia. Hyperglycemia has been shown to precede the diagnosis of ventilator-associated pneumonia (VAP) in critically injured adults and has been suggested to have potential diagnostic importance. However, glycemic control (GC) protocols in critically ill patients limit the development of hyperglycemia despite increasing insulin resistance. Our computer-assisted GC protocol achieves excellent GC, limiting infection-related hyperglycemia while capturing prospectively all glucose values, insulin infusion rates, and the multiplier (M) used to calculate the insulin rate. We hypothesized that surrogate measures of insulin resistance, the insulin infusion rate and multiplier M, would increase prior to the clinical suspicion of VAP, even in euglycemic critically injured patients.

METHODS

All critically injured patients (2,656) on the computerized glycemic control protocol were included in the analysis and categorized by those developing VAP and those without pneumonia on days 3-10 of their intensive care unit (ICU) stay. Median blood glucose concentration (BG), insulin infusion rate (IDR), and multiplier (M) [Insulin Drip Rate=M*(BG-60)] were determined for VAP patients (n=329) and non-infected ventilated (NIV) patients (n=2,327) on each day of mechanical ventilation. The day of VAP diagnosis according to U.S. Centers for Disease Control and Prevention (CDC) criteria was defined as day zero and VAP patients matched with NIV patients according to ventilator day from -10 to +10. Comparisons were conducted using the Mann-Whitney U test.

RESULTS

Baseline characteristics between VAP and NIV groups did not differ. Measures of insulin resistance increased from the time of injury in both groups. Patients with VAP had significantly greater change in both measures of insulin resistance, IDR and M, in the 48 hours preceding the diagnosis of VAP. These changes occurred despite the fact that the computer-assisted GC protocol achieved lower glucose values in VAP patients for the majority of study days.

CONCLUSIONS

Measures of insulin resistance increase in the two days prior to the clinical suspicion of VAP for critically injured patients on the GC protocol. These changes occur despite the protocol maintaining euglycemia. This data suggests that markers of insulin resistance may provide clinically useful information in the early diagnosis of VAP.

Distinct molecular phenotypes of direct vs indirect ARDS in single-center and multicenter studies

BACKGROUND

ARDS is a heterogeneous syndrome that encompasses lung injury from both direct and indirect sources. Direct ARDS (pneumonia, aspiration) has been hypothesized to cause more severe lung epithelial injury than indirect ARDS (eg, nonpulmonary sepsis); however, this hypothesis has not been well studied in humans.

METHODS

We measured plasma biomarkers of lung epithelial and endothelial injury and inflammation in a single-center study of 100 patients with ARDS and severe sepsis and in a secondary analysis of 853 patients with ARDS drawn from a multicenter randomized controlled trial. Biomarker levels in patients with direct vs indirect ARDS were compared in both cohorts.

RESULTS

In both studies, patients with direct ARDS had significantly higher levels of a biomarker of lung epithelial injury (surfactant protein D) and significantly lower levels of a biomarker of endothelial injury (angiopoietin-2) than those with indirect ARDS. These associations were robust to adjustment for severity of illness and ARDS severity. In the multicenter study, patients with direct ARDS also had lower levels of von Willebrand factor antigen and IL-6 and IL-8, markers of endothelial injury and inflammation, respectively. The prognostic value of the biomarkers was similar in direct and indirect ARDS.

CONCLUSIONS

Direct lung injury in humans is characterized by a molecular phenotype consistent with more severe lung epithelial injury and less severe endothelial injury. The opposite pattern was identified in indirect lung injury. Clinical trials of novel therapies targeted specifically at the lung epithelium or endothelium may benefit from preferentially enrolling patients with direct and indirect ARDS, respectively.

A pilot study of the noninvasive assessment of the lung microbiota as a potential tool for the early diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) remains a common complication in critically ill surgical patients, and its diagnosis remains problematic. Exhaled breath contains aerosolized droplets that reflect the lung microbiota. We hypothesized that exhaled breath condensate fluid (EBCF) in hygroscopic condenser humidifier/heat and moisture exchanger (HCH/HME) filters would contain bacterial DNA that qualitatively and quantitatively correlate with pathogens isolated from quantitative BAL samples obtained for clinical suspicion of pneumonia.

METHODS

Forty-eight adult patients who were mechanically ventilated and undergoing quantitative BAL (n = 51) for suspected pneumonia in the surgical ICU were enrolled. Per protocol, patients fulfilling VAP clinical criteria undergo quantitative BAL bacterial culture. Immediately prior to BAL, time-matched HCH/HME filters were collected for study of EBCF by real-time polymerase chain reaction. Additionally, convenience samples of serially collected filters in patients with BAL-diagnosed VAP were analyzed.

RESULTS

Forty-nine of 51 time-matched EBCF/BAL fluid samples were fully concordant (concordance > 95% by κ statistic) relative to identified pathogens and strongly correlated with clinical cultures. Regression analysis of quantitative bacterial DNA in paired samples revealed a statistically significant positive correlation (r = 0.85). In a convenience sample, qualitative and quantitative polymerase chain reaction analysis of serial HCH/HME samples for bacterial DNA demonstrated an increase in load that preceded the suspicion of pneumonia.

CONCLUSIONS

Bacterial DNA within EBCF demonstrates a high correlation with BAL fluid and clinical cultures. Bacterial DNA within EBCF increases prior to the suspicion of pneumonia. Further study of this novel approach may allow development of a noninvasive tool for the early diagnosis of VAP.

Insulin Resistance in Critically Injured Adults: Contribution of Pneumonia, Diabetes, Nutrition, and Acuity

PURPOSE

Changes in insulin resistance (IR) cause stress-induced hyperglycemia after trauma, but the numerous factors involved in IR have not been delineated clearly. We hypothesized that a statistical model could help determine the relative contribution of different clinical co-variates to IR in critically injured patients.

PATIENTS AND METHODS

We retrospectively studied 726 critically injured patients managed with a computer-assisted glycemic protocol at an academic level I trauma center (639 ventilated controls without pneumonia (VWP) and 87 patients with ventilator-associated pneumonia (VAP). Linear regression using age, gender, body mass index (BMI), diabetes mellitus, pneumonia, and glycemic provision was used to estimate M, a marker of IR that incorporates both the serum blood glucose concentration (BG) and insulin dose.

RESULTS

Increasing M (p<0.001) was associated with age (1.62%; 95% confidence interval [CI] 1.27%-1.97% per decade), male gender (9.78%; 95% CI 8.28%-12.6%), BMI (4.32% [95% CI 4.02%-4.62%] per 5 points), diabetes mellitus (21.2%; 95% CI 19.2%-23.2%), pneumonia (10.9%; 95% CI 9.31%-12.6%), and glycemic provision (27.3% [95% CI 6.6%-28.1%] per 100 g of glucose). Total parenteral nutrition was associated with a decrease in M of 10.3%; 95% CI 8.52%-12.1%; p<0.001.

CONCLUSIONS

Clinical factors can be used to construct a model of IR. Prospective validation might enable early detection and treatment of infection or other conditions associated with increased IR.

Impact of advanced practice providers (nurse practitioners and physician assistants) on surgical residents' critical care experience

BACKGROUND

Teaching hospitals often employ advanced practice providers (nurse practitioners and physician assistants or APPs) to counteract residents' work-hour restrictions. With increased utilization of APPs in labor-intense areas, such as intensive care units (ICUs), APPs may have an impact on resident education and experience. No studies have investigated the direct role an APP plays on the training experience of a surgical resident in the ICU.

MATERIALS AND METHODS

An institutional review board-approved survey was emailed to residents in Accreditation Council for Graduate Medical Education-accredited general surgery programs. Surveys asked about demographics, residency and/or ICU characteristics, and the effects of APPs on patient care, workflow, and educational experience. Regression analysis determined predictors of resident perception.

RESULTS

A total of 354 of 1178 residents responded to the survey (30%). Some residents felt that nurses calling APPs preferentially for patient-care issues interfered with education (17%) and residents' ability to follow patients (12%) and was associated with overall detrimental effects to ICU experience on regression (odds ratio, 3.7; confidence interval, 1.5-9.1). Most residents reported positive effects of APPs, such as reduced resident workload (79.8%), teaching protocols and/or guidelines (60.3%), enhanced patient care (60.3%), and enhanced communication (50.5%). When asked how APPs affected their overall ICU experience, 48.4% reported positive effects, 20.6% reported "no effect," and 31% reported detrimental effects.

CONCLUSIONS

Only a minority of residents perceived that APPs detract from training, particularly those who felt excluded when nurses preferentially contact APPs with patient-care issues. APPs have the potential to enhance training and ICU experience, as reflected in many of the responses. Strategies to maintain direct nurse and resident communication might preserve residents' perception of the educational value of APPs.