Effectiveness of Negative Pressure Wound Therapy During Aeromedical Evacuation Following Soft Tissue Injury and Infection.

INTRODUCTION: Negative pressure wound therapy (NPWT) is utilized early after soft tissue injury to promote tissue granulation and wound contraction. Early post-injury transfers via aeromedical evacuation (AE) to definitive care centers may actually induce wound bacterial proliferation. However, the effectiveness of NPWT or instillation NPWT in limiting bacterial proliferation during post-injury AE has not been studied. We hypothesized that instillation NPWT during simulated AE would decrease bacterial colonization within simple and complex soft tissue wounds. METHODS: The porcine models were anesthetized before any experiments. For the simple tissue wound model, two 4-cm dorsal wounds were created in 34.9 ± 0.6 kg pigs and were inoculated with Acinetobacter baumannii (AB) or Staphylococcus aureus 24 hours before a 4-hour simulated AE or ground control. During AE, animals were randomized to one of the five groups: wet-to-dry (WTD) dressing, NPWT, instillation NPWT with normal saline (NS-NPWT), instillation NPWT with Normosol-R® (NM-NPWT), and RX-4-NPWT with the RX-4 system. For the complex musculoskeletal wound, hind-limb wounds in the skin, subcutaneous tissue, peroneus tertius muscle, and tibia were created and inoculated with AB 24 hours before simulated AE with WTD or RX-4-NPWT dressings. Blood samples were collected at baseline, pre-flight, and 72 hours post-flight for inflammatory cytokines interleukin (IL)-1ß, IL-6, IL-8 and tumor necrosis factor alpha. Wound biopsies were obtained at 24 hours and 72 hours post-flight, and the bacteria were quantified. Vital signs were measured continuously during simulated AE and at each wound reassessment. RESULTS: No significant differences in hemodynamics or serum cytokines were noted between ground or simulated flight groups or over time in either wound model. Simulated AE alone did not affect bacterial proliferation compared to ground controls. The simple tissue wound arm demonstrated a significant decrease in Staphylococcus aureus and AB colony-forming units at 72 hours after simulated AE using RX-4-NPWT. NS-NPWT during AE more effectively prevented bacterial proliferation than the WTD dressing. There was no difference in colony-forming units among the various treatment groups at the ground level. CONCLUSION: The hypoxic, hypobaric environment of AE did not independently affect the bacterial growth after simple tissue wound or complex musculoskeletal wound. RX-4-NPWT provided the most effective bacterial reduction following simulated AE, followed by NS-NPWT. Future research will be necessary to determine ideal instillation fluids, negative pressure settings, and dressing change frequency before and during AE.

How Informed Is Your Informed Consent: Evaluating Differences Between Resident and Attending Obtained Consents for Cholecystectomy.

OBJECTIVE: There is considerable variability in surgeons' approach to write and obtain informed consent for surgery, particularly among resident trainees. We analyzed differences in procedures and complications described in documented surgical consents for cholecystectomy between residents and attendings. We hypothesized that attending consents would describe more comprehensive procedures and complications than those done by residents. DESIGN: This is a retrospective analysis of 334 patients who underwent cholecystectomy. Charts were queried for demographics, surgical approach, whether the consent was completed electronically, and which provider completed the consent. Specifically, consents were evaluated for inclusion of possible conversion to open procedure, intraoperative cholangiogram, bile duct injury, injury to nearby structures, reoperation, bile leak, as well as if the consent matched the actual procedure performed. SETTING: This study was conducted at an accredited general surgery training program at an academic tertiary care center in the Midwest. PARTICIPANTS: This was a review of 334 patients who underwent cholecystectomy over a 1 year period. RESULTS: Of all documented consents analyzed, 153 (47%) specifically included possible intraoperative cholangiogram, 156 (47%) included bile duct injury, 76 (23%) included injury to nearby structures, 22 (7%) included reoperation, and 62 (19%) included bile leak. In comparing residents and attendings, residents were more likely to consent for bile duct injury (p = 0.002), possible intraoperative cholangiogram (p = 0.0007), injury to nearby structures (p < 0.0001), reoperation (p < 0.0001), and bile leak (p < 0.0001). CONCLUSIONS: Significant variation exists between documentation between resident and attending cholecystectomy consents, with residents including more complications than attendings on their consent forms. These data suggest that experience alone does not predict content of written consents, particularly for common ambulatory procedures. Education regarding the purpose of informed consent and what should be included in one may lead to a reduction in variability between providers.

Postinjury Treatment to Mitigate the Effects of Aeromedical Evacuation After Traumatic Brain Injury in a Porcine Model.

INTRODUCTION: Early aeromedical evacuation after traumatic brain injury (TBI) has been associated with worse neurologic outcomes in murine studies and military populations. The goal of this study was to determine if commonly utilized medications, including allopurinol, propranolol, or tranexamic acid (TXA), could mitigate the secondary traumatic brain injury experienced during the hypobaric and hypoxic environment of aeromedical evacuation. METHODS: Porcine TBI was induced via controlled cortical injury. Twenty nonsurvival pigs were separated into four groups (n = 5 each): TBI+25 mL normal saline (NS), TBI+4 mg propranolol, TBI+100 mg allopurinol, and TBI+1g TXA. The pigs then underwent simulated AE to an altitude of 8000 ft for 4 h with an SpO2 of 82-85% and were sacrificed 4 h later. Hemodynamics, serum cytokines, and hippocampal p-tau accumulation were assessed. An additional survival cohort was partially completed with TBI/NS (n = 5), TBI/propranolol (n = 2) and TBI/allopurinol groups (n = 2) survived to postinjury day 7. RESULTS: There were no significant differences in hemodynamics, tissue oxygenation, cerebral blood flow, or physiologic markers between treatment groups and saline controls. Transient differences in IL-1b and IL-6 were noted but did not persist. Neurological Severity Score (NSS) was significantly lower in the TBI + allopurinol group on POD one compared to NS and propranolol groups. P-tau accumulation was decreased in the nonsurvival animals treated with allopurinol and TXA compared to the TBI/NS group. CONCLUSIONS: Allopurinol, propranolol, and TXA, following TBI, do not induce adverse changes in systemic or cerebral hemodynamics during or after a simulated postinjury flight. While transient changes were noted in systemic cytokines and p-tau accumulation, further investigation will be needed to determine any persistent neurological effects of injury, flight, and pharmacologic treatment.

Tracheostomy decreases continuous analgesia and sedation requirements.

BACKGROUND: The goals of sedation in the critically ill surgical patient are to minimize pain, anxiety, and agitation without hindering cardiopulmonary function. One potential benefit of tracheostomy during endotracheal intubation is the reduction of sedation and analgesia; however, there are little data to support this supposition. We hypothesized that patients undergoing tracheostomy would have a rapid reduction in sedation and analgesia following tracheostomy. METHODS: A retrospective review of tracheostomies performed at a single Level I trauma center from January 2013 to June 2018 was completed. An evaluation of Glasgow Coma Scale, Richmond Agitation-Sedation Scale, and Confusion Assessment Method for the intensive care unit 72 hours pretracheostomy to 72 hours posttracheostomy was performed. The total daily dose of sedation, anxiolytic, and analgesic medications administered were recorded. Mixed-effects models were used to evaluate longitudinal drug does over time (hours). RESULTS: Four hundred sixty-eight patients included for analysis with a mean age of 58.8 ± 18.3 years. There was a significant decrease in propofol and fentanyl utilization from 24 hours pretracheostomy to 24 hours posttracheostomy in both dose and number of patients receiving these continuous intravenous medications. Similarly, total morphine milligram equivalents (MME) use and continuous midazolam significantly decreased from 24 hours pretracheostomy to 24 hours posttracheostomy. By contrast, intermittent enteral quetiapine and methadone administration increased after tracheostomy. Importantly, Richmond Agitation-Sedation Scale, Glasgow Coma Scale, and Confusion Assessment Method scoring were also significantly improved as early as 24 hours posttracheostomy. Total MME use was significantly elevated in patients younger than 65 years and in male patients pretracheostomy compared with female patients. Patients admitted to the medical intensive care unit had significantly higher MME use compared with those in the surgical intensive care unit pretracheostomy. CONCLUSION: Tracheostomy allows for a rapid and significant reduction in intravenous sedation and analgesia medication utilization. Posttracheostomy sedation can transition to intermittent enteral medications, potentially contributing to the observed improvements in postoperative mental status and agitation. LEVEL OF EVIDENCE: Therapeutic/Care Management; Level III.

Effects of antifibrinolytics on systemic and cerebral inflammation after traumatic brain injury.

BACKGROUND: Administration of antifibrinolytic medications, including tranexamic acid (TXA), may reduce head injury-related mortality. The effect of these medications on post-traumatic brain injury (TBI) inflammatory response is unknown. The goal of this study was to investigate the role of available antifibrinolytic medications on both systemic and cerebral inflammation after TBI. METHODS: An established murine weight drop model was used to induce a moderate TBI. Mice were administered 1, 10, or 100 mg/kg of TXA, 400 mg/kg of aminocaproic acid (Amicar, Hospira, Lake Forest, IL), 100 kIU/kg of aprotonin, or equivalent volume of normal saline (NS) 10 minutes after recovery. Mice were euthanized at 1, 6, or 24 hours. Serum and cerebral tissue were analyzed for neuron-specific enolase and inflammatory cytokines. Hippocampal histology was evaluated at 30 days for phosphorylated tau accumulation. RESULTS: One hour after TBI, mice given TXA displayed decreased cerebral cytokine concentrations of tumor necrosis factor α (TNF-α) and, by 24 hours, displayed decreased concentrations of cerebral TNF-α, interleukin (IL)-6, and monocyte chemoattractant protein 1 compared with TBI-NS. However, serum concentrations of TNF-α and macrophage inflammatory protein 1α (MIP-1α) were significantly elevated from 1 to 24 hours in TBI-TXA groups compared with TBI-NS. The concentration of phosphorylated tau was significantly decreased in a dose-dependent manner in TBI-TXA groups compared with TBI-NS. By contrast, Amicar administration increased cerebral cytokine levels of IL-6 1 hour after TBI, with serum elevations noted in TNF-α, MIP-1α, and monocyte chemoattractant protein 1 at 24 hours compared with TBI-NS. Aprotonin administration increased serum TNF-α, IL-6, and MIP-1α from 1 to 24 hours without differences in cerebral cytokines compared with TBI-NS. CONCLUSION: Tranexamic acid administration may provide acute neuroinflammatory protection in a dose-dependent manner. Amicar administration may be detrimental after TBI with increased cerebral and systemic inflammatory effects. Aprotonin administration may increase systemic inflammation without significant contributions to neuroinflammation. While no antifibrinolytic medication improved systemic inflammation, these data suggest that TXA may provide the most beneficial inflammatory modulation after TBI.

Intercostal liposomal bupivacaine injection for rib fractures: A prospective randomized controlled trial.

BACKGROUND: Blunt chest wall injury accounts for 15% of trauma admissions. Previous studies have shown that the number of rib fractures predicts inpatient opioid requirements, raising concerns for pharmacologic consequences, including hypotension, delirium, and opioid dependence. We hypothesized that intercostal injection of liposomal bupivacaine would reduce analgesia needs and improve spirometry metrics in trauma patients with rib fractures. METHODS: A prospective, double-blinded, randomized placebo-control study was conducted at a Level I trauma center as a Food and Drug Administration investigational new drug study. Enrollment criteria included patients 18 years or older admitted to the intensive care unit with blunt chest wall trauma who could not achieve greater than 50% goal inspiratory capacity. Patients were randomized to liposomal bupivacaine or saline injections in up to six intercostal spaces. Primary outcome was to examine pain scores and breakthrough pain medications for 96-hour duration. The secondary endpoint was to evaluate the effects of analgesia on pulmonary physiology. RESULTS: One hundred patients were enrolled, 50 per cohort, with similar demographics (Injury Severity Score, 17.9 bupivacaine 17.6 control) and comorbidities. Enrolled patients had a mean age of 60.5 years, and 47% were female. Rib fracture number, distribution, and targets for injection were similar between groups. While both groups displayed a decrease in opioid use over time, there was no change in mean daily pain scores. The bupivacaine group achieved higher incentive spirometry volumes over Days 1 and 2 (1095 mL, 1063 mL bupivacaine vs. 900 mL, 866 mL control). Hospital and intensive care unit lengths of stay were similar and there were no differences in postinjection pneumonia, use of epidural catheters or adverse events bet ween groups. CONCLUSION: While intercostal liposomal bupivacaine injection is a safe method for rib fracture-related analgesia, it was not effective in reducing pain scores, opioid requirements, or hospital length of stay. Bupivacaine injection transiently improved incentive spirometry volumes, but without a reduction in the development of pneumonia. LEVEL OF EVIDENCE: Therapeutic/care management, Level II.

Blood product resuscitation mitigates the effects of aeromedical evacuation after polytrauma.

BACKGROUND: The combined injury of traumatic brain injury and hemorrhagic shock has been shown to worsen coagulopathy and systemic inflammation, thereby increasing posttraumatic morbidity and mortality. Aeromedical evacuation to definitive care may exacerbate postinjury morbidity because of the inherent hypobaric hypoxic environment. We hypothesized that blood product resuscitation may mitigate the adverse physiologic effects of postinjury flight. METHODS: An established porcine model of controlled cortical injury was used to induce traumatic brain injury. Intracerebral monitors were placed to record intracranial pressure, brain tissue oxygenation, and cerebral perfusion. Each of the 42 pigs was hemorrhaged to a goal mean arterial pressure of 40 ± 5 mm Hg for 1 hour. Pigs were grouped according to resuscitation strategy used-Lactated Ringer's (LR) or shed whole blood (WB)-then placed in an altitude chamber for 2 hours at ground, 8,000 ft, or 22,000 ft, and then observed for 4 hours. Hourly blood samples were analyzed for proinflammatory cytokines and lactate. Internal jugular vein blood flow was monitored continuously for microbubble formation with altitude changes. RESULTS: Cerebral perfusion, tissue oxygenation, and intracranial pressure were unchanged among the six study groups. Venous microbubbles were not observed even with differing altitude or resuscitation strategy. Serum lactate levels from hour 2 of flight to the end of observation were significantly elevated in 22,000 + LR compared with 8,000 + LR and 22,000 + WB. Serum IL-6 levels were significantly elevated in 22,000 + LR compared with 22,000 + WB, 8,000 + LR and ground+LR at hour 1 of observation. Serum tumor necrosis factor-α was significantly elevated at hour 2 of flight in 8,000 + LR versus ground+LR, and in 22,000 + LR vs. 22,000 + WB at hour 1 of observation. Serum IL-1ß was significantly elevated hour 1 of flight between 8,000 + LR and ground+LR. CONCLUSION: Crystalloid resuscitation during aeromedical transport may cause a prolonged lactic acidosis and proinflammatory response that can predispose multiple-injury patients to secondary cellular injury. This physiologic insult may be prevented by using blood product resuscitation strategies.

Impact of a Multimodal Analgesia Protocol on Inpatient and Outpatient Opioid Use in Acute Trauma.

BACKGROUND: Multimodal analgesia protocols have been implemented after elective surgery to reduce opioid use, however there is limited data on utility after polytrauma. Therefore, we investigated the impact of a multimodal analgesia protocol on inpatient and post-discharge outpatient opioid use after polytrauma. METHODS: A retrospective review of patients admitted to a Level I trauma center between September 2017-February 2018 (prior to multimodal protocol; "pre-cohort") and October 2018-April 2019 (after multimodal protocol; "post-cohort") was performed. An outpatient controlled substance registry was utilized to capture morphine milligram equivalents (MME) and gabapentin dispensed in the 6 mo after injury. RESULTS: 620 patients were included (295 pre-cohort, 325 post-cohort). Total inpatient MME decreased from 177.5 mg-130 mg (P= 0.01) between the cohorts. Daily inpatient MME decreased from 70.8 mg-44.7 mg (P< 0.01). Intravenous hydromorphone decreased from 2 mg in the pre-cohort to 1 mg in the post-cohort (P= 0.02). Inpatient oxycodone decreased from 45 mg-30 mg (P= 0.01). Concurrently, gabapentin increased from 0 mg-400 mg in the post-cohort (P< 0.01). Patients in the post-cohort were prescribed fewer MMEs than the pre-cohort at discharge (P< 0.05). However, the number of patients prescribed gabapentin increased from 6.1%-16% (P< 0.01). CONCLUSION: Implementation of an updated multimodal analgesia protocol decreased total MME, daily MME, hydromorphone, and oxycodone consumed while increasing gabapentin use. This suggests that while reducing opioid usage in-hospital is critical to reducing outpatient usage, multimodal pain protocols may lead to an increase in gabapentin prescriptions and utilization after discharge.

Acute and Chronic Hematologic Implications of Emergency and Elective Splenectomy.

INTRODUCTION: Thrombocytosis and leukocytosis are common after splenectomy. The potential effect of emergency surgery on these postoperative findings is unknown. We hypothesized that emergency splenectomy leads to a more profound and persistent hematologic change as compared to elective splenectomy. METHODS: A retrospective review was conducted of patients who underwent elective or trauma splenectomy. Records were queried for platelet (PLT) and white blood cell (WBC) count prior to splenectomy, on postoperative days 1-5, and at day 14, 1 month, 3 months, 6 months, and 1 year. Complications, including thromboembolic events, infection, need for repeat operation, and readmission within 30 days of discharge, were recorded. RESULTS: 463 patients were identified as being eligible for the study, with 173 patients in the elective cohort and 145 patients in each of the isolated trauma splenectomy and polytrauma cohorts. Both cohorts had peak thrombocytosis at week 2 postoperatively. However, polytrauma patients had a significantly higher peak platelet count (P < 0.01). The PLT:WBC ratio was lower in both trauma cohorts pre-operatively and postoperative day 1. Trauma splenectomy had a higher PLT:WBC ratio on days 2 and 3 whereas polytrauma had a lower ratio on days 4 and 5. Emergency cases had greater reoperation and infection rates, whereas elective cases were more likely to require readmission. Postoperative thromboembolic events were only higher in the polytrauma cohort. CONCLUSIONS: While trauma splenectomy resulted in more profound postoperative leukocytosis and thrombocytosis, there was no correlation with timing of infection or risk of thromboembolic events. These findings suggest that thrombocytosis and leukocytosis may be associated with thrombotic and infectious events but their presence alone does not indicate direct risks of concomitant infection or thrombosis.

Postinjury treatments to make early tactical aeromedical evacuation practical for the brain after TBI.

BACKGROUND: Traumatic brain injury (TBI) is common in civilians and military personnel. No potential therapeutics have been evaluated to prevent secondary injury induced by the hypobaric hypoxia (HH) environment integral to postinjury aeromedical evacuation (AE). We examined the role of allopurinol, propranolol, adenosine/lidocaine/magnesium (ALM), or amitriptyline administration prior to simulated flight following murine TBI. METHODS: Mice underwent TBI and were given allopurinol, propranolol, amitriptyline, or ALM prior to simulated AE or normobaric normoxia (NN) control. Heart rate (HR), respiratory rate, and oxygen saturation (Spo2) were recorded throughout simulated AE. Mice were sacrificed at 24 hours, 7 days, or 30 days. Serum and cerebral cytokines were assessed by enzyme-linked immunosorbent assay. Motor function testing was performed with Rotarod ambulation. Immunohistochemistry was conducted to examine phosphorylated tau (p-tau) accumulation in the hippocampus at 30 days. RESULTS: While all treatments improved oxygen saturation, propranolol, amitriptyline, and allopurinol improved AE-induced tachycardia. At 24 hours, both propranolol and amitriptyline reduced tumor necrosis factor alpha levels while allopurinol and ALM reduced tumor necrosis factor alpha levels only in NN mice. Propranolol, amitriptyline, and ALM demonstrated lower serum monocyte chemoattractant protein-1 7 days after AE. Both amitriptyline and allopurinol improved Rotarod times for AE mice while only allopurinol improved Rotarod times for NN mice. Propranolol was able to reduce p-tau accumulation under both HH and NN conditions while ALM only reduced p-tau in hypobaric hypoxic conditions. CONCLUSION: Propranolol lowered post-TBI HR with reduced proinflammatory effects, including p-tau reduction. Amitriptyline-induced lower post-TBI HR and improved functional outcomes without affecting inflammatory response. Allopurinol did not affect vital signs but improved late post-TBI systemic inflammation and functional outcomes. Adenosine/lidocaine/magnesium provided no short-term improvements but reduced p-tau accumulation at 30 days in the HH cohort. Allopurinol may be the best of the four treatments to help prevent short-term functional deficits while propranolol may address long-term effects. LEVEL OF EVIDENCE: Basic science article.

Acquisition and retention of surgical skills taught during intern surgical boot camp.

BACKGROUND: Surgical residencies have implemented boot-camps for early acquisition of basic technical skills for interns. However, educators worry that retention is poor. We hypothesized that a structured boot-camp curriculum would improve skills. METHODS: Interns underwent eight boot-camp sessions at the beginning of residency. Interns completed pre-, post-boot-camp, and end-of-year skills assessments, as well as post-boot camp and end-of-year porcine procedure labs. Proficiency was measured on a 5-point scale and by completion time. RESULTS: After boot-camp, interns improved all domains of knot-tying. Median time decreased for skin-closure (8.3 vs 9.9 min, p < 0.01), peg transfer (57 vs 87 s, p < 0.01), intracorporeal (178 vs 300 s, p < 0.01), and extracorporeal knot-tying (140 vs 259 s, p < 0.01). At the end-of-year assessment, interns exhibited retention of all skills and improved in knot-tying and central line skills. During the retention porcine lab, interns progressed basic but not complex skills. CONCLUSIONS: An eight-week boot-camp effectively improved technical skills among surgery interns. Interns retained all skills and improved upon techniques frequently practiced during intern year.

Mortality From Burns Sustained on Home Oxygen Therapy Exceeds Predicted Mortality.

The Boston Criteria and the Abbreviated Burn Severity Index are two widely accepted models for predicting mortality in burn patients. We aimed to elucidate whether these models are able to predict the risk of mortality in patients who sustain burns while smoking on home oxygen given their clinical fragility. We conducted a retrospective chart review of 48 patients admitted to our burn center from November 2013 to September 2017 who sustained a burn while smoking on home oxygen. Yearlong mortality was the primary outcome of the investigation; secondary outcomes included discharge to facility, length of stay, and need for tracheostomy. We calculated the expected mortality rate for each patient based on Boston Criteria and Abbreviated Burn Severity Index and compared the mortality rate observed in our cohort. Patients in our cohort suffered a 54% mortality rate within a year of injury, compared to a 23.5% mortality predicted by Boston Criteria, which was found to be statistically significant by chi-square analysis (P < .05). Abbreviated Burn Severity Index predicted mortality was 19.7%. While the absolute value of the difference in mortality was greater, this was not significant on chi-square analysis due to sample size. Our secondary outcomes revealed 42% discharge to facility, the average length of stay of 6.2 days, and 6.25% required tracheostomy. Patients whose burns are attributable to smoking on home oxygen may have an increased risk of mortality than prognostication models would suggest. This bears significant clinical impact, particularly regarding family and provider decision making in pursuing aggressive management.

Enhanced Recovery Protocol for Laparoscopic Sleeve Gastrectomy: Are Narcotics Necessary?

BACKGROUND: Enhanced recovery after surgery (ERAS) protocols have improved patient experience and outcomes in a variety of fields, including bariatric surgery. Given the increasing opioid epidemic in the USA, we sought to determine the impact of our own ERAS protocol on narcotic usage following laparoscopic sleeve gastrectomy. METHODS: Retrospective chart review was performed on patients undergoing primary laparoscopic sleeve gastrectomy for 6 months before and after implementation of an ERAS protocol. Our protocol strongly discouraged the use of narcotics in the postoperative period. Specific outcomes of interest were postoperative narcotic usage, length of stay, complications, and readmissions. RESULTS: Patient characteristics were similar in the two groups. ERAS implementation did not correlate with changes in length of stay, complications, or readmissions. However, ERAS implementation was associated with dramatic reductions in the use of intravenous narcotics (100% vs 47%, p < 0.01) and oral schedule 2 narcotics (56% vs 6%, p < 0.01), with an increase in the usage of tramadol (0% vs 36%, p < 0.01). After ERAS implementation, 52% of patients were managed without the use of schedule 2 narcotics (0% pre-ERAS, p < 0.01) and 33% received no narcotics of any kind (0% pre-ERAS, p < 0.01). CONCLUSION: Implementation of an ERAS protocol for laparoscopic sleeve gastrectomy is associated with a dramatic reduction in the use of narcotics in the postoperative period. This has implementation for the usage of narcotics for laparoscopic surgery and potential elimination of narcotics for certain patients and procedures.

Outpatient beta-blockers and survival from sepsis: Results from a national cohort of Medicare beneficiaries.

BACKGROUND: Elderly Americans suffer increased mortality from sepsis. Given that beta-blockers have been shown to be cardioprotective in critical care, we investigated outpatient beta-blocker prescriptions and mortality among Medicare beneficiaries admitted for sepsis. METHODS: We queried a 5% random sample of Medicare beneficiaries for patients admitted with sepsis. We used in-hospital and outpatient prescription drug claims to compare in-hospital and 30-day mortality based on pre-admission beta-blocker prescription and class of beta-blocker prescribed using univariate tests of comparison and multivariable logistic regression models and another class of medications for control. RESULTS: Outpatient beta-blocker prescription was associated with a statistically significant decrease in in-hospital and 30-day mortality. In multivariable modeling, beta-blocker prescription was associated with 31% decrease in in-hospital mortality and 41% decrease in 30-day mortality. Both cardioselective and non-selective beta-blockers conferred mortality benefit. CONCLUSIONS: Our data suggests that there may be a role for preadmission beta-blockers in reducing sepsis-related mortality.

Hypoxia enhances the phosphorylation and cytotoxicity of ganciclovir and zidovudine in Kaposi's sarcoma-associated herpesvirus infected cells.

Primary effusion lymphoma (PEL) is a rare B-cell lymphoma caused by Kaposi's sarcoma-associated herpesvirus (KSHV). PEL is poorly responsive to standard cytotoxic chemotherapy and portends a poor survival. Consequently, new effective treatment options are urgently needed. It is known that KSHV encodes two lytic genes, ORF36 (phosphotransferase) and KSHV ORF21 (thymidine kinase), which can phosphorylate ganciclovir and azidothymidine, respectively. Here, we have explored whether these genes can be used as therapeutic targets for PEL. PEL arises in pleural spaces and other effusions that provide a hypoxic environment. Based on Northern blot analysis, exposure of PEL cells to hypoxia up-regulated the expression of both ORF36 and ORF21. Using a newly developed nonradioactive reverse-phase high-performance liquid chromatography/mass spectrometry method to separate and quantify the phosphorylated forms of ganciclovir and azidothymidine, we found that PEL cells exposed to hypoxia produced increased amounts of the toxic triphosphates of these drugs. Moreover, we found that hypoxia increased the cell toxicity of ganciclovir and azidothymidine in PEL cells but had no significant effect on the herpesvirus-negative cell line CA46. These findings may have clinical applicability in the development of effective therapies for PEL or other KSHV-related malignancies.

Inhibition of HIV-1 replication by a peptide dimerization inhibitor of HIV-1 protease.

Peptides based on the amino (N) and carboxy (C)-terminal regions of human immunodeficiency virus type-1 (HIV-1) protease and on the C-terminus of p6* can inhibit HIV-1 protease activity by preventing dimerization. We developed a peptide dimerization inhibitor, P27, that included these domains and a cell permeable domain derived from HIV-1 Tat. P27 inhibited wild type (WT) and protease inhibitor (PI)-resistant HIV-1 protease (IC50: 0.23-0.32 microM). Kinetic and biochemical assays confirmed that P27 inhibits protease dimerization. Fluorescein-labeled peptide accumulated in MT-2 cells and protected acutely infected MT-2 cells from HIV-1-induced cytotoxicity (IC50: 5.1 microM). P27 also inhibited p24 accumulation from H9 and U937 cells chronically infected with WT or PI-resistant HIV-1. Immunoblot analysis on the supernatants and infected cells revealed a block in virus release by P27 rather than an inhibition of polyprotein processing. However, inhibition of p55 Gag processing by active-site inhibitors was enhanced when combined with P27, suggesting that P27 can affect protease function in maturing virions. Although P27 was rationally designed to block dimerization of the mature HIV-1 protease, the effects of P27 on HIV-1 replication may be related to partial inhibition of Gag-Pol processing leading to a disruption in virus release.

Identification of carboxypeptidase N as an enzyme responsible for C-terminal cleavage of stromal cell-derived factor-1alpha in the circulation.

The chemokine stromal-derived factor-1alpha (SDF-1alpha) is an essential regulator of hematopoiesis, lymphocyte homing, pre-B-cell growth, and angiogenesis. As SDF-1alpha is constitutively expressed in many tissues, chemokine function is mostly regulated by proteolytic degradation. Human serum cleaves the 68-amino acid chemokine, SDF-1alpha, at both termini. The enzyme or enzymes responsible for the removal of the carboxy-terminal lysine from SDF-1alpha, leading to significant reduction in biologic activity, have not been identified. Using a new biochemical assay for measuring the carboxy-terminal cleavage activity, we purified from serum and plasma a peptidase that specifically removes the carboxy-terminal lysine from SDF-1alpha and identified it as carboxypeptidase N (CPN, also known as kininase I, arginine carboxypeptidase, and anaphylotoxin inactivator). We demonstrate that SDF-1alpha in serum and plasma lacks the carboxy terminal lysine, and depletion of CPN from serum and plasma significantly reduces the SDF-1alpha carboxypeptidase activity. Purified CPN effectively and specifically removes the carboxy-terminal lysine from SDF-1alpha and significantly reduces the chemokine's biologic activity as a pre-B-cell growth factor and chemoattractant. Thus, in addition to its role as a regulator of the biologic activity of kinins and anaphylatoxins, CPN is an important regulator of the biologic activity of SDF-1alpha by reducing the chemokine-specific activity.