摘要:

BackgroundSplanchnic hypoperfusion is believed to be central in the pathogenesis of hemorrhagic shock–induced acute respiratory distress syndrome and multiple organ failure. Our previous work focused on the portal circulation as the conduit for gut-derived mediators of acute respiratory distress syndrome. Our current focus is the proinflammatory effects of postshock mesenteric lymph. We hypothesize that postshock lymph induces neutrophil (PMN)-mediated endothelial cell damage in an intercellular adhesion molecule-1 (ICAM-1)–dependent fashion, and devised a two-insult model to test this hypothesis.MethodsRats (n ≥ 5) underwent hemorrhagic shock (mean arterial pressure, 40 mm Hg for 30 minutes) and resuscitation (shed blood plus two times crystalloid) with lymph collection. Human pulmonary microvascular endothelial cells (HMVECs) were divided into three groups and grown to near confluence. Group 1 was incubated for 6 hours in 1% preshock or postshock lymph and ICAM-1 was measured by flow cytometry. Group 2 consisted of coculture of HMVECs and PMNs after endothelial cell activation to determine whether postshock lymph would stimulate PMN adherence. Group 3 was incubated under identical conditions, but PMNs were added for 30 minutes, and then activated with 4.5 &mgr;mol/L lysophosphatidylcholine (lyso-PC) for 1 hour to ascertain cytotoxicity. HMVEC density was measured using microscopy and recorded as HMVECs per millimeter squared. ICAM-1–blocking antibody and isotype control were used to assess the effects of ICAM-1 on PMN cytotoxicity. A buffer control was used for comparison using analysis of variance with Tukey’s correction.ResultsPostshock lymph activated HMVECs for increased surface expression of ICAM-1 and stimulated PMNs to adhere to endothelial cell monolayers. Activation of PMNs with lyso-PC in the presence of postshock lymph resulted in marked HMVEC death. The addition of an ICAM-1–blocking antibody abrogated this effect. Neither postshock lymph alone (758 ± 35 HMVECs/mm2), nor postshock lymph in the presence of quiescent PMNs alone (734 ± 28 HMVECs/mm2), nor lymph plus lyso-PC (834 ± 21 HMVECs/mm2) provoked endothelial cell damage.ConclusionPostshock mesenteric lymph activates endothelial cells for increased ICAM-1 expression and PMN adherence. Furthermore, postshock lymph acts as an inciting event in a two-event in vitro model of PMN-mediated endothelial cell injury. These findings further substantiate the key mechanistic role of mesenteric lymph in hemorrhagic shock–induced acute lung injury and suggest that ICAM-1 expression is pivotal in the two-event model of multiple organ failure.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundThe purpose of this study was to evaluate the relative importance of systemic hypercoagulability, preexisting and acquired risk factors, and specific injury patterns in the development of venous thromboembolism (VTE) after injury.MethodsInjured patients with an Injury Severity Score ≥ 15 were followed with lower extremity venous duplex ultrasonography, prothrombin fragment 1 + 2, and quantitative D-dimer levels at 1 and 3 days and then weekly until discharge.ResultsAmong 101 patients with a mean Injury Severity Score of 27.3 ± 10.5 followed for 12.4 ± 8.7 days, 28 (27.7%) developed a lower extremity thrombosis, 2 (1.9%) sustained a pulmonary embolism, and 1 (0.9%) had a symptomatic upper extremity thrombosis. Although admission fragment 1 + 2 and D-dimer levels were elevated in 81.4% and 100% of patients, respectively, mean levels were not significantly different in those with or without VTE. VTE was more common (p< 0.05) among those with obesity, age > 40 years, immobilization for > 3 days, spine fractures, and lower extremity fractures. However, only obesity (p= 0.004) and immobilization > 3 days (p= 0.05) were independent predictors of VTE in a multivariate analysis.ConclusionAlthough elevated in seriously injured patients, neither markers of activated coagulation nor specific injury patterns are predictive of VTE. Associations with immobilization and obesity suggest that VTE after injury is a systemic hypercoagulable disorder with local manifestations of thrombosis related to lower extremity stasis.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ObjectiveWith rising health care costs, methods to decrease length of hospital stay without compromising care are necessary. One area that extends length of stay in trauma patients is inpatient anticoagulation to a therapeutic international normalized ratio. The 1998 American College of Chest Physicians guidelines recommend thromboprophylaxis with low-molecular-weight heparin (LMWH) and oral warfarin in this population. The LMWH Expedited Anticoagulation Program (LEAP) was created with the following goals: to decrease the number of inpatient warfarin days and to reduce overall number of hospital days.MethodsInpatient anticoagulation was initiated with warfarin and LMWH. LEAP included early multidisciplinary collaboration to ensure third-party approval, outpatient primary care physician follow-up, and LMWH self-injection before discharge. Patients were discharged on LMWH (discontinued by primary care provider when a therapeutic international normalized ratio was attained) and warfarin (continued until resolution of orthopedic injuries). From August 2000 to August 2001, adult patients were included in the prospective study. Primary inclusion criteria were blunt acetabular fracture, bilateral lower extremity fracture, and contralateral upper and lower extremity fractures. Patients with similar injuries receiving warfarin for deep venous thrombosis prophylaxis between June 1999 and June 2000 were the control population. Anticoagulation care was similar for the study and control subjects.ResultsThere were 182 patients evaluated for LEAP inclusion. After initial evaluation, 108 patients were enrolled in LEAP (Injury Severity Score of 13). There were 69 control subjects (Injury Severity Score of 13). The average number of inpatient warfarin days was decreased from 8.8 days to 5.0 days in the control and study populations, respectively (p< 0.0001). The average length of hospitalization was shortened from 17.3 days in the control group to 12.9 days in the study (LEAP) population (p< 0.002).ConclusionLEAP has successfully decreased the number of inpatient days on warfarin and total hospital days for trauma patients requiring deep venous thrombosis prophylaxis. These results have substantially decreased health care costs and increased available hospital beds in this era of high hospital occupancy.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundMixed venous saturation (Svo2) represents the oxygen extraction ratio (O2ER) through the following relationship: Svo2≈ 1 − O2ER, assuming a negligible contribution of dissolved oxygen to blood oxygen content. We sought to determine whether altered Fio2levels would affect the correlation between Svo2and O2ER.MethodsA theoretical analysis was performed to determine the extent to which Svo2should be affected by different Fio2levels at various ranges of O2ER using several linked spreadsheets. The relationships obtained were compared with actual patient data stored in a large patient data set.ResultsTheoretical analysis indicated that increases in Fio2should produce a small stepwise increase in the observed Svo2that is independent of O2ER. However, analysis of 8,324 simultaneous data points for Svo2and O2ER failed to demonstrate this pattern, primarily because patients with higher Fio2concentrations tend to have higher O2ERs, and hence lower Svo2.ConclusionSvo2measurements are not significantly affected by Fio2levels in critically ill patients.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundThe ideal resuscitation fluid for the trauma patient would be readily available to prehospital personnel, universally compatible, effective when given in small volumes, and capable of reversing tissue hypoxia in critical organ beds. Recently developed hemoglobin-based oxygen-carrying solutions possess many of these properties, but their ability to restore tissue oxygen after hemorrhagic shock has not been established. We postulated that a small-volume resuscitation with HBOC-201 (Biopure) would be more effective than either lactated Ringer’s (LR) solution or hypertonic saline dextran (HSD) in restoring baseline tissue oxygen tension levels in selected tissue beds after hemorrhagic shock. We further hypothesized that changes in tissue oxygen tension measurements in the deltoid muscle would reflect the changes seen in the liver and could thus be used as a monitor of splanchnic resuscitation.MethodsThis study was a prospective, blinded, randomized resuscitation protocol using anesthetized swine (n = 30), and was modeled to approximate an urban prehospital clinical time course. After instrumentation and splenectomy, polarographic tissue oxygen probes were placed into the liver (liver Po2) and deltoid muscle (muscle Po2) for continuous tissue oxygen monitoring. Swine were hemorrhaged to a mean arterial pressure (MAP) of 40 mm Hg over 20 minutes, shock was maintained for another 20 minutes, and then 100% oxygen was administered. Animals were then randomized to receive one of three solutions: LR (12 mL/kg), HSD (4 mL/kg), or HBOC-201 (6 mL/kg). Physiologic variables were monitored continuously during all phases of the experiment and for 2 hours postresuscitation.ResultsAt a MAP of 40 mm Hg, tissue Po2was 20 mm Hg or less in both the liver and muscle beds. There were no significant differences in measured liver or muscle Po2values after resuscitation with any of the three solutions in this model of hemorrhagic shock. When comparing the hemodynamic effects of resuscitation, the cardiac output was increased from shock values in all three animal groups with resuscitation, but was significantly higher in the animals resuscitated with HSD. Similarly, MAP was increased by all solutions during resuscitation, but remained significantly below baseline except in the group of animals receiving HBOC-201 (p< 0.01). HBOC-201 was most effective in both restoring and sustaining MAP and systolic blood pressure. There was excellent correlation between liver and deltoid muscle tissue oxygen values (r= 0.8,p< 0.0001).ConclusionHBOC-201 can be administered safely in small doses and compared favorably to resuscitation with HSD and LR solution in this prehospital model of hemorrhagic shock. HBOC-201 is significantly more effective than HSD and LR solution in restoring MAP and systolic blood pressure to normal values. Deltoid muscle Po2reflects liver Po2and thus may serve as an index of the adequacy of resuscitation in critical tissue beds.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundNuclear factor-kappa B (NF-&kgr;B) plays a critical role in the cellular response to a variety of stimuli, and it regulates the production of various inflammatory cytokines, adhesion molecules, and enzymes. Polymorphonuclear leukocytes (PMNLs) play a central role in systemic inflammatory response after severe insult. The role of NF-&kgr;B in activation of PMNLs, however, has not been clear. We developed a simple flow cytometric method for quantifying expression of intranuclear NF-&kgr;B in PMNLs, and we used it to evaluate NF-&kgr;B activity in patients with systemic inflammatory response syndrome (SIRS).MethodsThirty patients who fulfilled the criteria for SIRS and 24 healthy volunteers were included as study subjects. Expression of intranuclear NF-&kgr;B with and without stimulation by lipopolysaccharide was quantified by our new method. Oxidative activity in PMNLs with and without formylmethionyl-leucyl-phenylalanine stimulation was measured by flow cytometry. Levels of interleukin-6, interleukin-8, PMNL elastase, and nitric oxide metabolites in blood were also measured.ResultsExpression of intranuclear NF-&kgr;B in PMNLs both with and without LPS stimulation was significantly elevated in SIRS patients in comparison with that of healthy volunteers. PMNL oxidative activity was significantly elevated in SIRS patients. Positive correlation was observed between intranuclear NF-&kgr;B expression and PMNL oxidative activity, whereas no relation was observed between intranuclear NF-&kgr;B expression and serum concentrations of chemical mediators.ConclusionOur new flow cytometric method proved useful for quantifying intranuclear NF-&kgr;B expression in PMNLs. In PMNLs from SIRS patients, intranuclear NF-&kgr;B expression and oxidative activity were significantly elevated with positive correlation, and enhanced expression of NF-&kgr;B may play an important role in PMNL activation in SIRS.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundOlder adults (aged ≥ 65 years) represent the single fastest growing segment of the United States population and will comprise one in five Americans during the third decade of this century. As this population segment rapidly expands, lower extremity fractures (LE Fx) and their associated disability will become a greater public health concern. The purpose of this study was to quantify the risk for LE Fx from motor vehicle collisions (MVCs) according to age.MethodsThe 1995 to 2000 National Automotive Sampling System data files were used. Study entry was limited to front-seat occupants involved in frontal MVCs. Risk ratios for LE Fx and age were adjusted for gender, driver versus passenger, seat belt use, airbag deployment, delta-V, intrusion, and vehicle type.ResultsBeginning in the fourth decade, there was a trend of higher relative risk for LE Fx with age that reached statistical significance in the seventh decade of life.ConclusionThis study documented an increased risk of LE Fx in older MVC occupants. Efforts to prevent these disabling injuries and to better protect occupants’ lower extremities in MVCs should include improved vehicle design and reevaluation of the existing federal motor vehicle safety standards.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundThe purpose of this study was to identify and analyze factors contributing to both airbag deployment and resulting head injuries (HIs) and to quantify the effect of airbag deployment on head injuries, in terms of odds of head injury and severity, in severe motor vehicle collisions (MVCs).MethodsData were derived from severely injured (Injury Severity Score [ISS] > 12) drivers treated at Ontario’s lead trauma hospitals (n = 1,272), and included all MVC driver deaths in the province (n = 665) from 1997–98. We conducted an epidemiologic description and a case-control study to compare drivers with and without HIs. Statistical analysis included Pearson’s &khgr;2, Wilcoxon rank-sum, and multiple logistic regression tests.ResultsSeventy-one percent of drivers were men, peaking in the 25- to 34-year age group. The most common impact involved multiple vehicles (62%) approaching each other. Overall, 59% of crashes had a frontal location of impact. HIs were significantly associated with a lower age (median, 36 vs. 43 years), seat belt use (53% vs. 59%), and airbag deployment (7% vs. 10%), with higher ISS (median, 34 vs. 22), ejection (20% vs. 10%), and mortality rate (44% vs. 35%). Airbag deployment was associated with higher age and seat belt use, and lower ISS, ejection, and deaths. Importantly, there were fewer HIs with the deployment of an airbag (64% vs. 73%) and a lower severity of HI. When logistic regression was used to control for the effects of possible confounders, airbag deployment was not statistically associated with one’s odds of HI (odds ratio, 0.827; 95% confidence interval, 0.560–1.220), but ISS, age, and ejection were.ConclusionAirbag deployment did not significantly lower a driver’s odds of head injury in a severe MVC, but it did significantly lower the severity of head injury. This is a significant finding, given that 72% of our study population sustained a head injury and the importance of lowering the severity of these head injuries in terms of patients’ ultimate outcome. The most important factor associated with head injuries was ejection, which nearly doubled a driver’s odds of head injury (odds ratio, 1.759; 95% confidence interval, 1.201–2.577). This reinforces the supplementary protective effect of an airbag and that “buckling up” and keeping occupants in the vehicle is of primary importance in the prevention of head injuries.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundTo date, attempts to assess the relationship between motor vehicle collision (MVC)-related mortality and medical resources availability have largely been unsuccessful.MethodsInformation regarding sociodemographic characteristics, prehospital resources, and hospital-based resources for each county (n = 67) in the state of Alabama was obtained. MVC-related mortality rates (deaths per 1,000 collisions) by county were calculated and compared according to prehospital and hospital-based resource availability within each county after correcting for sociodemographic factors.ResultsCounties with 24-hour availability of a general surgeon, orthopedic surgeon, neurosurgeon, computed tomographic scanner, and operating room were shown to have decreased MVC-related mortality (relative risk [RR], 0.88). The same was true for those counties with hospitals classified as Level I-II (RR, 0.71) and Level III-IV (RR, 0.83) trauma centers compared with counties with no trauma centers.ConclusionAppropriate, readily available hospital-based resources are associated with lower MVC-related mortality rates. This information may be useful in trauma system planning and development.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

BackgroundUncontrolled hemorrhage is the leading preventable cause of death on the battlefield. Similarly, hemorrhage accounts for 80% of all deaths within the first 48 hours of injury in civilian trauma patients. New methods of hemostasis are required to reduce hemorrhagic mortality. The purpose of this study was to compare nine hemostatic dressings for their efficacy in controlling bleeding from an otherwise fatal aortic injury in a pig model. Each hemostatic dressing was compared with the current standard U.S. Army field gauze dressing for a 1-hour period.MethodsFifty-nine anesthetized pigs were instrumented with catheters and splenectomized. Nine test dressings (n = 5 per group) and two control groups (gauze, n = 9; suture, n = 5) were applied to a 4.4-mm aortotomy through the spraying jet of blood, and direct pressure was held for 4 minutes and then released. Survival, blood loss, and other variables were measured over a 1-hour period.ResultsAll animals with fibrin dressing and those receiving suture repair (five of five in both groups) survived the 1-hour observation period with minimal bleeding in the postocclusion period (< 37 mL). Those in the other dressing groups exsanguinated within 10 minutes, except for two animals in the gauze group surviving 1 hour.ConclusionWith one 4-minute application, a single fibrin dressing stopped bleeding from an aortotomy, which was equivalent to sutured repair. No other test group exhibited any evidence of significant hemostatic efficacy.

ISSN:0022-5282    

出版商:OVID    

年代:2003

数据来源: OVID