Search PubMed⌕ Search

Biomedical subjects

R V Maier

Publications and source records attributed to R V Maier.

At least 73 records · Page 4Linked to original sources
PubMed1996

Limiting computed tomography to patients with peritoneal lavage-positive results reduces cost and unnecessary celiotomies in blunt trauma.

OBJECTIVE: To determine if computed tomographic (CT) scanning can be used to identify patients with blunt trauma, positive results of diagnostic peritoneal lavage (DPL), and a stable hemodynamic status who could be managed safely and cost-effectively without celiotomy. DESIGN: Patients with blunt trauma who required an abdominal evaluation underwent DPL. Patients with a red blood cell count greater than 10(11)/L (10(5)/mm3) on lavage then underwent CT. Patients with solid organ injury alone, as detected on CT scan, were observed; those with evidence of hollow viscus injury underwent celiotomy. RESULTS: Sixty-seven hemodynamically stable patients had a red blood cell count greater than 10(11)/L on DPL; 38 patients underwent subsequent CT scanning, and 29 underwent immediate celiotomy in violation of the protocol. Eleven patients in the protocol group ultimately underwent celiotomy. Overall, there were significantly fewer nontherapeutic celiotomies performed in the protocol group (2/38 vs 9/29, P < .01). There were no deaths in either group. Because DPL is less expensive than CT, limiting CT to patients with DPL-positive results and hemodynamic stability reduced the charges associated with abdominal evaluation by $580,594 over a period of 2 years. CONCLUSION: Limiting CT to the evaluation of patients with DPL-positive results and hemodynamic stability is safe, reduces charges, and results in a lower rate of nontherapeutic celiotomies compared with DPL alone.

Abdominal Injuries↗
PubMed1996

Prostaglandin E2 production by endotoxin-stimulated alveolar macrophages is regulated by phospholipase C pathways.

BACKGROUND: Eicosanoids play an important role in many aspects of systemic inflammatory responses and host defense. Although the synthesis of eicosanoids by different enzymes has been elucidated, the regulatory mechanism of eicosanoid production is not clear. We designed this study to investigate the hypothesis that PGE2 production by endotoxin (lipopolysaccharide; LPS)-stimulated macrophages (MO) is dependent on phospholipase C (PLC) signaling pathways. METHODS: Rabbit alveolar macrophages (MO) were obtained by bronchoalveolar lavage. MO were suspended in RPMI-1640 medium at 1 x 10(6)/mL and were exposed to Escherichia coli LPS (10 ng/mL) +/- various agonists and antagonists of PLC and its secondary messengers. After 24 hours of incubation, prostaglandin E2 (PGE2) production was measured by ELISA. RESULTS: LPS-activated MO produced four times as much PGE2 as did control unstimulated MO. The increase in PGE2 production was inhibited by PLC inhibitors (U73122 or D609) and a low-molecular-weight PLA2 inhibitor, manoalide. An increase in intracellular calcium and activation of both the calmodulin and protein kinase C kinase pathways increase PGE2 production. CONCLUSIONS: PGE2 production is intimately dependent on several phospholipases. Production is not only dependent on low-molecular-weight PLA2 cleavage of arachidonic acid from membrane phospholipids, but also by-products of PLC activation. PLC-dependent intracellular Ca-calmodulin signaling and protein kinase C activation provide significant modulation of PGE2 production.

Animals↗
PubMed1996

Trauma recidivism in the elderly.

BACKGROUND: The incidence of recurrent trauma in the elderly is unknown. This study evaluated the risk of readmission for injury among elderly trauma patients compared with an uninjured geriatric cohort. The effects of age, sex, race, preexisting illness, and ISS on trauma recidivism were determined. METHODS: Population based retrospective cohort analysis of the elderly using administrative data from the Health Care Financing Administration was performed. The measured outcome was trauma admission within 5 years. The injured were identified using hospital discharge data and the Injury Severity Score generated by ICD-Map. The uninjured were identified from Medicare eligibility files. Comorbid illness was assessed using ICD-9CM codes from outpatient and inpatient data files. RESULTS: The injured members of the cohort had increased risk of subsequent new trauma admission (p < 0.001). Increasing Injury Severity Score, age, and comorbid illness are associated with trauma recidivism. CONCLUSION: Trauma in the elderly is recurrent. Further study is required to develop age and injury specific interventions to prevent recurrent injury.

Age Distribution↗
PubMed1996

Effects of supplemental dietary arginine, canola oil, and trace elements on cellular immune function in critically injured patients.

Dietary nutrients may have pharmacological value in modulating the immune system. We studied the effects of two enteral diets, which differed in their content of arginine, fat source, and select trace elements, on immune function in critically injured patients. Leukocytes were isolated from healthy volunteers and severely injured (ISS > 13) patients on the first, sixth, and tenth day of receiving either a standard diet or experimental diet. Monocytes were assayed for tumor necrosis factor, procoagulant activity, and prostaglandin E2 following endotoxin exposure. Neutrophil oxidant production and lymphocyte blastogenesis was assessed. Leukocyte function was uniformly depressed compared to normal patients on day 1. The response of leukocytes from patients receiving experimental diet improved or "normalized" by day 6, while remaining depressed in patients receiving standard diet. Dietary nutrient modification can effect cellular immune responses to inflammatory stimuli in severely injured patients.

Adolescent↗
PubMed1996

Surgical treatment of myasthenia gravis in two major Middle East teaching hospitals: factors influencing outcome.

BACKGROUND: The results of thymectomy on patients with generalised myasthenia gravis have been widely reported. However, there is no information on whether the experience of western countries can be generalised to the population of the Middle East. The purpose of this study was to evaluate the safety and efficacy of thymectomy in patients with myasthenia gravis in a Middle East patient population and to identify clinical and histopathological factors associated with improved long term outcome of surgery. METHODS: In a prospective study, sixty three patients (aged 1.5-51 years) were treated in two university teaching hospitals between 1984 and 1991 and followed up for a mean of four years. Close communication was established with neurologists to obtain early referral. Radical anterior mediastinal dissection through a median sternotomy was performed in all patients. The response was evaluated by modified Osserman's classification. RESULTS: Eighteen patients achieved complete remission and a further 39 improved, producing an overall response rate of 90.5%. Patients with milder disease (stage II) had a higher response rate (97%) than those with more advanced disease (78%). Patients operated on with less than three years of symptoms had a better outcome (94%) than those with longer duration of preoperative symptoms, especially in non-thymomatous patients. Age and sex had no effect on the outcome. There was no effect on response rate if patients had hyperplastic or non-specific thymic histological findings, but patients with thymoma fared worse. CONCLUSIONS: These results are comparable with reports from the western world and represent the first prospective study from the Middle East. Thymectomy is indicated for all patients suffering from generalised myasthenia gravis soon after the diagnosis is made, regardless of age, stage, thymic pathology, and preoperative clinical status.

Adolescent↗
PubMed1996

Assessment of two clinical trials: interferon-gamma therapy in severe injury.

Two recent studies have examined the efficacy of interferon-gamma in reducing infection and death in patients sustaining severe injury. Both included multi-center, randomized, double-blinded placebo-control design. The first trial, conducted at four university trauma centers, enrolled 213 patients, while the second trial involved nine university trauma centers and 416 subjects. Recombinant human interferon-gamma (100 micrograms) was administered subcutaneously daily for 10 days in the first trial and 21 days in the second, in addition to standard supportive therapy. In both trials infection rates were similar in the treatment arms. Although the death rate related to infection was not affected in the first study, the second trial suggested an improved outcome from this complication. The outcome of the larger trial was flawed by dominant findings at one center that had the highest enrollment, infection, and death rates. Confounding variable analysis presented here explains much of the difference between center findings in the larger trial. Thus, the benefit of interferon-gamma as an immune adjuvant in severe injury is clouded by study design flaws evaluating its use and by the inability to identify appropriate subjects using clinical criteria.

Adolescent↗
PubMed1996

Endothelial changes after shock and injury.

The endothelial cell (EC) was once though to be a passive bystander in the inflammatory response to shock and injury. We now know, however, that these cells play a central role in the coordination of the response to injury. Hypovolemic shock following traumatic injury initiates two primary mechanisms of cellular damage. These include ischemia/reperfusion injury and acute inflammation. The EC has four key functions that are altered by these states: a) control of coagulation, b) regulation of vascular tone, c) control of vascular permeability, and d) regulation of leukocyte adhesion and trafficking. In the settings of ischemia/reperfusion and acute inflammation, the EC takes on a proinflammatory phenotype and as such becomes prothrombotic, demonstrates enhanced vascular permeability, and becomes chemoattractant, facilitating leukocyte adhesion, activation, and migration. In this article, we explore each of the four EC functions in detail along with the alterations that occur when the proinflammatory phenotype becomes manifest. In addition, we elucidate novel therapeutic strategies that have arisen from this research.

Animals↗
PubMed1996

Oxidants augment endotoxin-induced activation of alveolar macrophages.

Endotoxin (lipopolysaccharide) stimulation of macrophages (M phi) induces the generation of toxic reactive oxygen intermediates (ROI); however, recent studies implicate intracellular redox changes in signal transduction pathways for cytokines. To test whether oxidant stress modulates M phi activation, rabbit alveolar M phi were exposed to the following: diamide (oxidizes intracellular glutathione); glucose oxidase (generates hydrogen peroxide); or xanthine oxidase (generates superoxide), before lipopolysaccharide. Supernatants were assayed for tumor necrosis factor (TNF) and cell lysates were assayed for procoagulant activity (PCA). TNF mRNA was analyzed by Northern blot. M phi exposure to diamide and glucose oxidase augmented TNF production, PCA expression, and TNF mRNA accumulation; however, xanthine oxidase exposure inhibited TNF production while augmenting PCA expression. M phi signal transduction can be enhanced by increasing cellular oxidant stress. The differential response of TNF versus PCA suggests the existence of distinct redox-sensitive signal transduction pathways. These data define a mechanism by which oxidants generated during inflammation may modulate M phi function.

Animals↗
PubMed1995

Progress in the development of trauma systems in the United States. Results of a national survey.

OBJECTIVE: To examine the status of trauma system development and key structural and operational characteristics of these systems. DESIGN AND SETTING: National survey of trauma systems with enabling state statute, regulation, or executive orders and for which designated trauma centers were present. PARTICIPANTS: Trauma system administrators and directors of 37 state and regional organizations that had legal authority to administer trauma systems, which represented a response rate of 90.2%. MAIN OUTCOME MEASURES: Trauma system components that had been implemented or were under development. RESULTS: From 1988 to 1993, the number of states meeting one set of criteria for a complete trauma system criteria increased from two to five. The most common deficiency in establishing trauma systems was failure to limit the number of designated trauma centers based on community need. Although most existing trauma systems have developed formal processes for designating trauma centers, prehospital triage protocols to allow hospital bypass, and centralized trauma registries, several systems lack standardized policies for interhospital transfer and systemwide evaluation. CONCLUSION: State and regional organizations have accomplished a great deal but still have substantial work ahead in developing comprehensive trauma systems. Research is needed to better understand the relationship between trauma volume and outcomes of care as well as the impact of trauma system structure and operational characteristics on care delivery. Improved measures of patient outcome are also needed so that effective system evaluation can take place.

Clinical Protocols↗
PubMed1995

Do prehospital trauma center triage criteria identify major trauma victims?

OBJECTIVE: To evaluate anatomic, physiologic, and mechanism-of-injury prehospital triage criteria as well as the subjective criterion of provider "gut feeling." DESIGN: Prospective analysis. SETTING: A state without a trauma system or official trauma center designation. PATIENTS: Patients treated by emergency medical services personnel statewide over a 1-year period who were injured and met at least one prehospital triage criterion for treatment at a trauma center. MAIN OUTCOME MEASURES: Outcome was analyzed for injury severity using the Injury Severity Score and mortality rates. A major trauma victim (MTV) was defined as a patient having an Injury Severity Score of 16 or greater. The yield of MTV and mortality associated with each criterion was determined. RESULTS: Of 5028 patients entered into the study, 3006 exhibited a singular entry criterion. Triage criteria tended to stratify into high-, intermediate-, and low-yield groups for MTV identification. Physiologic criteria were high yield and anatomic criteria were intermediate yield. Provider gut feeling alone was a low-yield criterion but served to enhance the yield of mechanism of injury criteria when the two criteria were applied in the same patient. CONCLUSIONS: A limited set of high-yield prehospital criteria are acceptable indicators of MTV. Isolated low- and intermediate-yield criteria may not be useful for initiating trauma center triage or full activation of hospital trauma teams.

Adolescent↗
PubMed1995

TPN-induced sympathetic activation is related to diet, bacterial translocation, and an intravenous line.

OBJECTIVE: To investigate the effects of an intravenous line and the administration of a total parenteral nutrition (TPN) formula by the parenteral and oral routes on bacterial translocation and urinary catecholamine excretion in rodents. METHODS: Rats were fed chow with or without an intravenous line and a fat-free TPN solution either orally or intravenously for 5 consecutive days. Urine was collected on the first, third, and fifth days of feeding and quantitatively analyzed for norepinephrine and epinephrine excretion. Mesenteric lymph nodes were cultured for bacteria at the end of the study (day 5). RESULTS: Oral and intravenous TPN diets significantly increased norepinephrine excretion over time (P < .0001) compared with excretion in rats fed chow. Oral TPN diets increased epinephrine secretion after 5 days of feeding. The route of feeding TPN solution had no effect on norepinephrine or epinephrine excretion. Chow-fed rats with intravenous lines tended to have increased norepinephrine excretion over 5 days of feeding compared with chow-fed rats without intravenous lines (55% vs 13%, P = .08). Rats with bacterial translocation had greater norepinephrine excretion (mean +/- SEM, 136 +/- 23 pmol/mumol of creatinine) than rats without bacterial translocation (64 +/- 14 pmol/mumol of creatinine) (P < .05). CONCLUSIONS: Intravenous and oral fat-free, hypertonic glucose diets increase sympathetic nervous activity. This diet-induced sympathetic activity may be related to the presence of an intravenous line, bacterial translocation, the thermic effects of hypertonic glucose, and/or the absence of orally ingested food substances in rodent chow. In this model of rodent feeding, increased sympathetic activity may account for alterations in intestinal and immunologic defenses.

Administration, Oral↗
PubMed1995

Clinical significance of antibiotic endotoxin-releasing properties in trauma patients.

OBJECTIVE: To test the hypothesis that antibiotics leading to greater endotoxin release are associated with greater mortality in septic trauma patients. DESIGN: Post hoc analysis of data from a previously conducted prospective, randomized, multicenter study designed to evaluate the efficacy of interferon gamma in preventing infection and death in trauma patients. SETTING: Nine level I trauma centers. PATIENTS: Severely injured trauma patients at high risk for sepsis. Eighty percent (N = 334) of the enrolled patients developed some manifestation of gram-negative sepsis, defined by the administration of gram-negative specific antibiotics. MAIN OUTCOME MEASURES: The in-hospital mortality rate of patients who received penicillin-binding protein 3/tumor necrosis factor (PBP3/TNF)-specific antibiotics associated with the greatest degree of endotoxin release and TNF production (PBP3/TNF group, n = 78: aztreonam, ceftazidime, and cefotaxime sodium) was compared with that of patients not receiving these agents (non-PBP3/TNF group, n = 256). RESULTS: Mortality in the PBP3/TNF group (17%) was higher than in the non-PBP3/TNF group (8%, P = .02). The two groups were similar in their mean (+/- SD) Injury Severity Scores (34 +/- 9), ages (31 +/- 12 years), and initial degree of bacterial contamination. CONCLUSIONS: Antibiotics that are associated with greater release of endotoxin and production of TNF are also associated with greater mortality in septic trauma patients. Decisions regarding antibiotic administration may need to consider the endotoxin-releasing properties of antibiotics in addition to their antibacterial sensitivity spectrum. Prospective studies of the effect of endotoxin-releasing properties of antibiotics on mortality are warranted.

Adult↗
PubMed1995

Factors influencing outcome in stab wounds of the heart.

BACKGROUND: The purpose of this study was to identify factors associated with unfavorable outcome following stab wounds to the heart in order to improve selection of patients who may benefit from aggressive resuscitative efforts. METHODS: Preoperative and operative variables were reviewed for all patients treated for cardiac stab wounds at a level I trauma center from 1987 to 1993 in an attempt to identify factors influencing survival. RESULTS: Twenty-nine (53%) of the 55 patients who were resuscitated following stab wounds to the heart during the study period survived. Although profound hypotension (systolic blood pressure < 40 mm Hg), cardiopulmonary resuscitation, and emergency room thoracotomies were associated with poor outcome, none were uniformly predictive of death. Some patients survived with each of these characteristics. CONCLUSIONS: We recommend that all patients suspected of having cardiac stab wounds be fully resuscitated and undergo thoracotomy, as significant survival can be achieved and death is not always the outcome.

Adult↗
PubMed1995

Antioxidants attenuate endotoxin-induced activation of alveolar macrophages.

BACKGROUND: Endotoxin (lipopolysaccharide [LPS]) stimulation of tissue-fixed macrophages induces the generation of toxic oxidants. However, recent studies also implicate redox changes in both the signal transduction pathways for cytokine genes and the generation of physiologically active arachidonic acid metabolites. Because cytokines and arachidonic acid metabolites initiate and perpetuate deleterious systemic inflammatory responses, we tested whether macrophage activation could be modulated by antioxidants. METHODS: Rabbit alveolar macrophages were obtained by bronchoalveolar lavage, isolated, treated with the antioxidants vitamin E or N-acetylcysteine (NAC), and stimulated with an optimal dose of LPS (10 ng/ml). Assays were performed for tumor necrosis factor (TNF), procoagulant activity, and prostaglandin E2. Total cellular RNA was extracted for Northern blot analysis of TNF messenger RNA. RESULTS: Exposure of the macrophage to the antioxidants vitamin E and NAC inhibited TNF production, accumulation of TNF messenger RNA, procoagulant activity expression, and prostaglandin E2 production. CONCLUSIONS: Macrophage signal transduction of LPS is dependent on the generation of reactive oxygen intermediates that can be blocked both at the level of the lipid membrane (vitamin E) and at the intracellular level (NAC). This suggests a potential therapeutic role for antioxidants is disease states such as adult respiratory distress syndrome and multiple organ failure syndrome, which are characterized by excessive macrophage activation.

Acetylcysteine↗
PubMed1995

From roadside to bedside: the regionalization of trauma care in a remote rural county.

OBJECTIVE: To determine the current role of rural hospitals and prehospital agencies in the care of motor vehicle crash victims in a remote, rural county prior to the statewide regionalization of trauma care. Specifically, we determined the proportion of crashes that required a response by emergency medical services (EMSs), the timeliness of the response, the proportion of patients treated in local hospitals, and the factors that predicted referral to trauma centers. DESIGN: Population-based retrospective cohort study linking emergency medical services, emergency department, and hospital discharge data to police motor vehicle crash reports and coroner data. SETTING: Okanogan County, Washington. SUBJECTS: All motor vehicle occupants, pedestrians or pedalcyclists who were involved in a motor vehicle collision with a response by emergency medical system personnel or the county coroner. INTERVENTION: None. MAIN OUTCOME MEASURES: EMS response times, emergency department and hospital discharge disposition, Injury Severity Scores, hospital length of stay, procedures, deaths. RESULTS: Twelve percent of 669 crashes reported to the police led to the dispatch of EMS. Crashes with EMS involvement were more likely to include occupants without restraints, who were ejected from the vehicle or who had alcohol as a contributing circumstance. The median interval between crash and EMS dispatch was 5 minutes (95th percentile: 40 minutes), the median scene time was 15 minutes (95th percentile: 35 minutes), and the median interval between dispatch and emergency department arrival was 48 minutes (95th percentile: 95 minutes). Among the 210 patients treated by EMSs, 67 (32%) were admitted to local hospitals, and 19 (9%) were referred to a distant trauma center. Of these, 17 were referred directly from the emergency department, one from the scene, and one after local admission. Compared with patients who were admitted locally, referred patients had a significantly higher mean Injury Severity Score (14.4 vs. 5.1), hospital length of stay (9.1 vs. 1.8 days), and rate of operative procedures (37% vs. 9%). Of the 13 crash-related deaths during the year, nine were declared dead at the scene before EMS arrival, three were asystolic at the time of EMS arrival at the scene, and one died at a referral hospital. CONCLUSIONS: The linkage of data from police, prehospital agencies, and hospitals can reveal important information about the sequence of health care for trauma patients. The rural hospitals in this county currently play a major role in the stabilization and treatment of motor vehicle crash victims.

Accidents, Traffic↗
PubMed1995

Traumatic visceral artery aneurysm: presentation as massive hemorrhage from perforation into an adjacent hollow viscus.

BACKGROUND: While diagnosis of extremity pseudoaneurysm is usually straightforward, pseudoaneurysms arising from visceral arteries may be occult. Perforation of a visceral artery pseudoaneurysm into an adjacent hollow viscus with subsequent hemorrhage has been rarely reported. OBJECTIVE AND DESIGN: To retrospectively evaluate the cause, clinical presentation, and outcome of patients with bleeding traumatic visceral artery aneurysms. MATERIALS AND METHODS: Records of nine patients with visceral hemorrhage due to posttraumatic arterial aneurysms. RESULTS: All had penetrating torso trauma 2 to 52 (mean, 12.3) weeks before presentation to our facility and had undergone 1 to 5 (mean, 2.2) prior operations. They had 2 to 15 episodes of hemorrhage into the gastrointestinal (seven cases), respiratory (one case), and urinary (one case) tracts. All underwent emergent surgery with ligation of the involved artery and resection of the corresponding portion of viscus. Evidence of prior attempts at hemostasis with multiple heavy ligatures was evident in all cases. All patients recovered without further complications. CONCLUSIONS: Traumatic visceral artery aneurysms are usually due to penetrating trauma. They present as episodes of massive bleeding through one of the hollow viscera, and may stop bleeding without direct intervention only to occur again. Prompt operative therapy is usually necessary.

Adolescent↗
PubMed1995

Injury prevention strategies to promote helmet use decrease severe head injuries at a level I trauma center.

Head injuries (HIs) remain a major contributor to trauma mortality, with many deaths occurring despite optimal use of available therapy. Injury prevention is vital to decrease the impact of HIs. Helmets can decrease the severity of HIs in both bicycle crashes (BCs) and motorcycle crashes (MCCs). A major challenge is to increase helmet use. A mandatory motorcycle helmet law in 1990 and information campaigns aimed at bicyclists have increased the percentage of riders wearing helmets in Washington State. We hypothesized that there would be an associated decrease in the proportion of severe HIs in BC and MCC admissions to the state's only level I trauma center. We analyzed injury region and outcomes for all 466 BC and 992 MCC instate admissions from 1986 to 1993. For BCs, the proportion of severe HIs (Abbreviated Injury Scale score of 4 or 5) declined from 29% in 1986 to 11% in 1993 (p = 0.02). BC trends paralleled helmet use in observations on 8,860 bicycle riders in the area, in which the percentage of helmeted riders rose from 5% in 1987 to 62% in 1993 (p < 0.001). For MCCs, severe HIs declined from 20% before passage of the helmet law to 9% afterward (p < 0.001). Mortality decreased for BCs and MCCs (p < 0.05), and length of hospital stay and ICU stay decreased for BCs (p < 0.05). The percentage of helmeted BC admissions rose from 0% to 32% (p = 0.009), and helmeted MCC admissions rose from 41% to 80% (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Accidents, Traffic↗