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Biomedical subjects

S R Shackford

Publications and source records attributed to S R Shackford.

At least 37 records · Page 2Linked to original sources
PubMed1997

Trauma deaths in a mature urban vs rural trauma system. A comparison.

OBJECTIVE: To compare the timing, severity, and injury characteristics of patients dying from trauma in an urban vs a rural setting. DESIGN: Retrospective review of autopsy database (urban) and medical examiner database (rural), with selected medical chart review. SETTING: An organized urban trauma system with 6 trauma centers and a rural state with no formal trauma system and 1 trauma center. PATIENTS: All trauma fatalities occurring in an urban (n = 612) and a rural (n = 143) setting during a 1-year period. RESULTS: In the urban system, 248 patients (40.5%) died at the scene of injury compared with 103 (72%) patients in a rural environment. During the first 24 hours of hospitalization 243 (39.7%) urban patients died compared with 23 (16%) rural patients. Eighty-nine urban patients (14.5%) and 17 rural patients (11.8%) survived for more than 24 hours but later died in the hospital. The mean age of those who died was significantly greater in the rural trauma system than in the urban trauma system (P < .001), and the Injury Severity Score was significantly less in the rural trauma system than in the urban trauma system (P < .01). In the patients who died after being admitted to the hospital for more than 24 hours there was a significantly higher rate of preexisting comorbidity in the rural patients than in the urban patients (P < .05). The most frequent cause of death in the rural setting was multisystem organ failure; head injury was the most common cause of death in the urban setting. CONCLUSIONS: Patients who die in a rural area without a formal trauma system are more likely to die at the scene, are less severely injured, and are older. Rural trauma patients who are admitted to a hospital and who survived for at least 24 hours before dying are older, less severely injured, have significantly more comorbidities, and are more likely to die of multisystem organ dysfunction than their urban counterparts. These differences reflect the different patient populations and injury patterns that confront urban and rural trauma centers. The higher proportion of scene deaths in the rural environment may reflect the longer discovery and transport times that occur in a rural setting.

Adolescent↗
PubMed1997

Prophylactic vena cava filter insertion in selected high-risk orthopaedic trauma patients.

OBJECTIVES: (a) To determine the incidence and risk factors for the development of pulmonary embolism in orthopaedic trauma patients and (b) to determine whether prophylactic vena cava filters are efficacious against pulmonary edema in high-risk patients. DESIGNS: Before and after trial on the incidence of pulmonary embolism in the orthopaedic trauma population before and after the introduction of prophylactic vena cava filters. SETTING: Tertiary care level I trauma center. PATIENTS: Thirty-five patients received prophylactic vena cava filters. These patients had a long bone and pelvic, multiple long bone fractures, or a complex (Kane's III or IV) pelvic fracture with at least one additional risk-factor at an age of > 55 years and an Injury Severity Score of > 16 or requiring prolonged (> 6 weeks) immobilization. INTERVENTION: Thirty-five patients had vena cava filters placed (32 titanium Greenfield filters, Medi-tech/Boston Scientific, Watertown, MA; and three Bird's Nest filters, Cook Bloomington, IN). Most filters (n = 33) were placed percutaneously in radiology. MAIN OUTCOME MEASURES: (a) Morbidity related to filter insertion, (b) incidence of pulmonary embolism in orthopaedic trauma population compared with historical controls who did not receive filters, and (c) patency of filters. RESULTS AND CONCLUSIONS: Minimal morbidity was related to prophylactic vena cava filter insertion. There was a significant (p < 0.04); (Fisher's exact) decrease in the incidence of pulmonary embolism in the orthopaedic trauma population as a whole after the use of prophylactic vena cava filters. Follow-up ultrasound showed a 1 and 2-year inferior vena cava patency rate of 93.6% +/- 6.2% by life table analysis. We conclude that selected use of prophylactic vena cava filters in orthopaedic trauma is safe and decreases the incidence of pulmonary embolism.

Fractures, Bone↗
PubMed1997

Effect of small-volume resuscitation on intracranial pressure and related cerebral variables.

BACKGROUND: Head injury outcome is adversely affected by the presence of hypotension. Therapies directed at rapidly correcting hypotension may improve outcome. METHODS: In two separate studies, we investigated small-volume resuscitation (4 mL/kg) using Ringer's lactate, hypertonic saline and dextran, and diaspirin cross-linked hemoglobin in a porcine model of cryogenic brain injury and shock. RESULTS: Small-volume resuscitation with hypertonic saline and dextran and diaspirin cross-linked hemoglobin significantly improved mean arterial pressure and cerebral perfusion pressure compared with Ringer's lactate. These data suggest that small-volume resuscitation with hypertonic saline and dextran or diaspirin cross-linked hemoglobin may effectively limit or prevent secondary ischemic brain injury after head injury and shock.

Animals↗
PubMed1997

Production of tumor necrosis factor-alpha and interleukin-1beta by human cerebral microvascular endothelium after percussive trauma.

Intracerebral cytokine production is thought to be partially responsible for the brain edema and increased leukocyte adhesion seen after head injury by both a direct effect on vascular permeability and by causing leukocyte activation. Cerebrospinal fluid concentrations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 are elevated after traumatic brain injury. The cerebral endothelium has not been investigated as a de novo source of cytokines after injury. We have found that conditioned media from cultured human cerebral microvascular endothelium (HCME) subjected to percussion trauma increases neutrophil chemotaxis. To test the hypothesis that percussive trauma increases the production of TNF-alpha and IL-1beta by HCME, serial supernatant samples from passage 2 HCME were collected for 24 hours and analyzed for TNF-alpha and IL-1beta concentration by enzyme-linked immunosorbent assay after trauma. HCME subjected to percussion injury secreted significantly more TNF-alpha at 8 and 24 hours and significantly more IL-1beta at 4 and 24 hours compared with uninjured controls (p < 0.05, Student's t test). These data suggest that HCME production of inflammatory cytokines occurs after traumatic brain injury independent of systemic influences. In situ cytokine production by HCME after percussion trauma may mediate the increased cerebral leukocyte accumulation and cerebrovascular dysfunction observed after focal brain injury.

Brain Injuries↗
PubMed1997

Financial outcome of treating trauma in a rural environment.

The financial plight of the urban trauma center is well documented. However, the financial status of the rural trauma center is largely unknown. We hypothesized that our rural trauma center with a high number of blunt trauma patients, a wide spectrum of injury severity, and a large percentage of insured patients would prove to be financially advantageous to the institution. From January 1994 to June 1995, 1,119 consecutive trauma admissions had a complete financial profile compiled including actual costs, reimbursements, and reimbursement ratio (RR = reimbursement/actual costs). Our injury severity profile was very skewed with a preponderance of less severely injured patients (mean Injury Severity Score = 9.6 +/- 7.8). The payor profile of these patients included 49.2% fee-for-service (RR = 1.43), 25.4% diagnosis-related group-based (RR = 0.92), 8.77% per diem (RR = 0.51), and 1.25% capitated (RR = 0.47). Overall, the RR for the trauma unit was 1.11, representing a net profit overall. Cost closely tracked both hospital and intensive-care unit length of stay (R2 = 0.925). Likewise, reimbursement also was reflected in both hospital and intensive-care unit length of stay (R2 = 0.735). We conclude that our rural trauma center, with a favorable payor mix and low injury severity, is financially profitable.

Adult↗
PubMed1997

Trauma registry injury coding is superfluous: a comparison of outcome prediction based on trauma registry International Classification of Diseases-Ninth Revision (ICD-9) and hospital information system ICD-9 codes.

BACKGROUND: Trauma registries are an essential but expensive tool for monitoring trauma system performance. The time required to catalog patients' injuries is the source of much of this expense. Typically, 15 minutes of chart review per patient are required, which in a busy trauma center may represent 25% of a full-time employee. We hypothesized that International Classification of Disease-Ninth Revision (ICD-9) codes generated by the hospital information system (HI) would be similar to those coded by a dedicated trauma registrar (TR) and would be as accurate as TR ICD-9 codes in predicting outcome. METHODS: One thousand eight hundred twelve patients admitted to a Level I trauma center during 2 years had International Classification of Disease Injury Severity Scores (ICISS) calculated based on HI and TR ICD-9 codes. The relative predictive powers of these two ICISSs were then compared for every patient using Receiver Operator Characteristic Curve Area (ROC) and Hosmer Lemeshow Statistics. RESULTS: Eighty-nine percent of patients (1,608 of 1,812) had identical HI and TR ICISSs. Eleven patients' ICISSs differed by >0.1, and only two patients' scores differed by >0.2. ICISS proved to be a powerful predictor of outcome whether derived from HI (ROC = 0.884; 95% confidence interval (CI) = 0.850-0.917) or TR (ROC = 0.872; 95% CI = 0.837-0.908). Although these predictive powers were not significantly different (p = 0.076), the trend was for HI to perform better than TR. ISS calculated for the same data set using the MacKenzie dictionary proved significantly less predictive of outcome than either ICISS (ROC(MacKenzie) = 0.843; 95% CI = 0.792-0.884; p = 0.034). CONCLUSION: We conclude that in our hospital TR data on individual injuries can be replaced by HI data without loss of predictive power. ISS based on the MacKenzie dictionary should be abandoned because it is much less predictive of outcome than ICISS.

Adolescent↗
PubMed1997

Outcome after blunt traumatic thoracic aortic laceration: identification of a high-risk cohort. Western Trauma Association Multicenter Study Group.

BACKGROUND: Specific cohorts of patients with blunt traumatic thoracic aortic laceration (BTTAL) might benefit from conservative or delayed management. We hypothesized that age and comorbidities would predict outcome. METHODS: BTTAL data from 14 trauma centers over 11 years. Hospital and autopsy records of confirmed BTTAL were retrospectively reviewed. Regression analysis evaluated outcome by trauma indices, age, premorbidities, interventions, adjuvant therapy, and delay of repair. RESULTS: Three hundred ninety-five cases of BTTAL were identified, 233 who were stable. Stable cohort survival was 71.9%. No trauma indices predicted outcome. Comorbidities, especially coronary artery disease (CAD), were associated with mortality. The use of beta-blocking agents and maintenance of normal blood pressure were associated with survival. Delay of >4 hours to operative repair was not associated with increased mortality. Increasing age was associated with higher mortality. Multivariate regression found CAD and AGE predictive of mortality (log odds formula: exp [-2.0858 + 0.0253(AGE) + 2.0428(CAD)]). CONCLUSIONS: AGE and CAD are associated with worse outcome in stable BTTAL patients undergoing operative repair. Treating comorbidities and managing associated injuries should be undertaken in stable BTTAL patients. Physiologic stability should be established before repair of BTTAL.

Adult↗
PubMed1997

Effect of hemodilution with diaspirin cross-linked hemoglobin on intracranial pressure, cerebral perfusion pressure, and fluid requirements after head injury and shock.

Hemodilution has been shown to increase cerebral blood flow (CBF) and reduce lesion volume in models of occlusive cerebral ischemia, but it has not been evaluated in the setting of head trauma and shock in which ischemia is thought to play a role in the evolution of secondary injury. In a porcine model of brain injury and shock the authors compared hemodilution with diaspirin cross-linked hemoglobin (DCLHb) to a standard resuscitation regimen using Ringer's lactate solution and shed blood. After creation of a cryogenic brain injury followed by hemorrhage, the animals received a bolus of either 4 ml/kg of Ringer's lactate solution (Group 1, six animals) or DCLHb (Group 2, six animals), followed by infusion of Ringer's lactate solution to restore mean arterial pressure (MAP) to baseline. Group 1 received shed blood 1 hour after hemorrhage (R1) in the form of packed red blood cells. Group 2 received shed blood only for an Hb count of less than 5 g/dl. The animals were monitored for 24 hours. At R1, Group 2 had a significantly greater cerebral perfusion pressure ([CPP] 88 +/- 5.7 vs. 68 +/- 2.4 mm Hg, p < 0.05). By 3 hours after hemorrhage (R3) Group 2 had a significantly lower Hb concentration (8.5 +/- 0.4 vs. 12.1 +/- 0.3 g/dl, p < 0.05) and a significantly lower intracranial pressure ([ICP] 9 +/- 0.8 vs. 14 +/- 0.6 mm Hg, p < 0.05). The total 24-hour fluid requirement was significantly less in Group 2 (10,654 +/- 505 ml vs. 15,542 +/- 1094 ml, p < 0.05) There was no difference between the groups regarding levels of regional CBF in the injured hemisphere. Cerebral O2 delivery was not significantly different between groups at any time. Lesion volume as determined at postmortem examination was not significantly different between the groups. The increased MAP and CPP and lower ICP observed in the Group 2 animals indicate that hemodilution with DCLHb may be beneficial in the treatment of head injury and shock.

Animals↗
PubMed1996

Selective nonoperative management of liver and spleen injuries in neurologically impaired adult patients.

BACKGROUND: Nonoperative management of blunt liver and spleen injuries in hemodynamically stable, neurologically intact patients has become an accepted treatment in recent years. OBJECTIVE: To determine the morbidity and mortality in neurologically impaired adult patients who had sustained blunt liver or spleen injuries and who had been managed nonoperatively in a monitored setting, owing to the preponderance of blunt trauma and associated head injuries in Vermont. DESIGN: Case-control study. SETTING: Regional level I trauma center in northern Vermont. PATIENTS: One hundred eighty-seven consecutive patients with documented blunt splenic or hepatic trauma who were admitted to a regional rural trauma referral center in Vermont during an 8-year period, beginning in January 1987, were studied. Hemodynamically stable patients underwent diagnostic imaging studies and were classified by mental status as either normal or altered. Patients who required operative intervention were excluded. MAIN OUTCOME MEASURES: Morbidity and mortality rates for each group were recorded and compared to determine if statistically significant differences between the two groups existed. RESULTS: The groups were similar in age, systolic blood pressure, and hematocrit at admission. The group of patients with an altered mental status were more severely injured and had a longer hospital stay. Intensive care unit stays were not significantly different. Transfusion requirements for both groups were minimal; however, the group of patients with an altered mental status received more blood transfusions compared with the group of patients with a normal mental status. There was no significant difference in morbidity and mortality between the two groups. There were no failures of nonoperative management, no complications, and no missed visceral injuries in the group of patients with an altered mental status. Patients older than 50 years had higher morbidity and mortality. CONCLUSIONS: Nonoperative management in patients with an altered mental status can be done safely in a monitored setting. This challenges the current criteria of excluding neurologically impaired patients with liver or spleen trauma from nonoperative management.

Adolescent↗
PubMed1996

The effects of hyperosmolarity on the viability and function of endothelial cells.

Hypertonic solutions have been demonstrated to be efficacious in the treatment of hypovolemic shock. Their continued use when serum osmolarity is elevated may be harmful because they induce cellular dehydration. Because the hyperosmotic tolerance of cells is largely unknown, we determined the effects of increased media osmolarity on in vitro endothelial cell viability and function following periods of normoxia, anoxia, and anoxia with reoxygenation. Bovine aortic endothelial cells were exposed to hypertonic media of 330-570 mOsm/liter for 6-30 hr. Cell viability and function were ascertained utilizing trypan blue exclusion, lactate dehydrogenase (LDH) enzyme release, and cell replating assays. Endothelial cells exposed to media of 460 mOsm/liter demonstrated no significant decrease in the percentage of viable cells (69.81 +/- 6.03 vs 70.64 +/- 4.62% for controls), LDH activity (334.67 +/- 7.91 vs 228.03 +/- 191.28 Berger-Broida U/ml), and replating efficiency (58.27 +/- 42.07 vs 59.10 +/- 5.79%) after 30 hr of normoxic incubation. Hypertonic media up to 570 mOsm/liter did not adversely affect cell viability following a 6-hr anoxic insult. A 6-hr anoxic insult followed by 24 hr of reoxygenation in media of 530 and 570 mOsm/liter resulted in significantly increased viability and replating efficiency compared to 30 hr of normoxia. Our data demonstrate that in vitro endothelial cells tolerate media osmolarity of up to 460 mOsm/liter without apparent decrement in viability or replating efficiency even in adverse conditions of anoxia and reoxygenation. Our data also suggest that exposure to anoxia may induce tolerance of endothelial cells to hyperosmotic media.

Animals↗
PubMed1996

The effect of lesion volume on cerebral vasomotor tone after focal brain injury and shock.

We have previously shown that the volume of a focal brain injury influences cerebral blood flow. We hypothesized that the cerebral vasomotor tone after traumatic brain injury and shock is related to lesion volume and that the size of the lesion would affect vasomotor reactivity. Swine were randomized to receive either a large or small cryogenic injury followed by shock, and were studied for 5 h postresuscitation. A small brain injury and shock produced a significant and sustained increase in bihemispheric pial arteriolar diameter when compared to the large lesion group and controls. A large brain injury and shock resulted in a significant decrease in the pial arteriolar diameter in the injured hemisphere. We also noted significant differences between and within groups in interhemispheric pial arteriolar diameter and pial arteriolar reactivity to acetylcholine and hypocarbia. These data suggest that the volume of injured tissue influences cerebral blood flow by a vascular mechanism, which may be due in part to an alteration in cerebral endothelial cell function.

Animals↗
PubMed1996

Influence of percussion trauma on expression of intercellular adhesion molecule-1 (ICAM-1) by human cerebral microvascular endothelium.

OBJECTIVES: Brain injury is associated with the production of oxygen free radicals (OFR) and the accumulation of polymorphonuclear leukocytes (PMN) at the site of injury, both of which may be involved in the evolution of secondary cerebral injury. Intercellular adhesion molecule-1 (ICAM-1) is responsible for adherence of PMNs. We sought to determine whether percussion trauma altered the expression of ICAM-1 and to determine the effect of OFR scavengers on ICAM-1 expression after percussion trauma. DESIGN: Prospective controlled laboratory research using passage 2 human cerebral microvascular endothelium (HCME). MATERIALS AND METHODS: Cell lysates were collected over 24 hours and analyzed for ICAM-1 by enzyme-linked immunosorbent assay (ELISA) after trauma or incubation with tumor necrosis factor (TNF)-alpha. OFR scavengers were added immediately after trauma with or without previous incubation with TNF-alpha. MEASUREMENTS AND MAIN RESULTS: Sublethal percussion trauma did not alter ICAM-1 expression by HCME. TNF-alpha upregulated ICAM-1 in percussed and nonpercussed cells with maximal ICAM-1 expression at 24 hours (p < 0.01, ANOVA). However, percussion trauma significantly blunted the response of HCME to TNF-alpha. The addition of OFR scavengers after percussion trauma alone had no effect on ICAM-1 expression at 24 hours, but restored the response of percussed HCME to TNF-alpha. CONCLUSIONS: Percussion trauma alters the response of HCME to cytokine-induced ICAM-1 upregulation, and the normal response is restored by OFR scavengers. This suggests that HCME become dysfunctional after percussion trauma and this dysfunction may be mediated by OFR.

Barotrauma↗
PubMed1996

Diaspirin cross-linked hemoglobin resuscitation improves cerebral perfusion after head injury and shock.

BACKGROUND: Shock associated with traumatic brain injury (TBI) doubles the mortality of TBI alone by inducing a secondary ischemic injury. Rapid correction of cerebral perfusion pressure (CPP) is thought to be essential to improving outcome. Diaspirin cross-linked hemoglobin (DCLHb) has been shown to improve cerebral blood flow, increase mean arterial pressure (MAP), and reduce lesion size in models of occlusive cerebral ischemia but has not been evaluated in a model of TBI combined with hemorrhagic shock. METHODS: We studied the effects of DCLHb resuscitation in a porcine model of cryogenic TBI and hemorrhagic shock (MAP = 50 mmHg). After combined insults, animals were randomized to receive a bolus of 4 mliters/kg of either lactated Ringer's solution (n = 5) or DCLHb (n = 6). Lactated Ringer's solution was then infused in both groups to maintain MAP at baseline. Shed blood was returned 1 hour after the initiation of resuscitation (R1). Animals were studied for 24 hours. RESULTS: DCLHb infusion resulted in a significantly greater MAP at R1 and R24 (95 +/- 4 vs. 82 +/- 2 and 99 +/- 3 vs. 85 +/- 3 mm Hg, respectively) and a significantly greater CPP at R1 and R24 (83 +/- 10 vs. 68 +/- 5 and 89 +/- 6 vs. 71 +/- 11 mm Hg, respectively). Intracranial pressure was lower in the DCLHb group, but this difference was not significant. There was no significant difference between the groups in cerebral oxygen delivery. DCLHb animals required less fluid to maintain MAP (12,094 +/- 552 vs. 15,542 +/- 1094 mliters, p < 0.05). CONCLUSION: These data suggest that DCLHb is beneficial in the early resuscitation of head injury and shock and that further investigation is warranted. Key Words: Diaspirin cross-linked hemoglobin, Head injury, Shock, Cerebral perfusion pressure.

Animals↗