Biomedical subjects

D Hoyt

Publications and source records attributed to D Hoyt.

14 recordsLinked to original sources

PubMed2001

Use of vascularized fibular grafts as a salvage procedure for previously failed spinal arthrodesis.

STUDY DESIGN: A case series of spinal arthrodesis performed with vascularized fibular grafts is presented. OBJECTIVES: The use of vascularized fibular grafts to obtain anterior spinal fusion in patients with complex spinal disorders and poor fusion environments is described. SUMMARY OF BACKGROUND DATA: The fusion success of spinal arthrodesis is dependent on numerous factors, such as the substrate used for arthrodesis (i.e., graft), the biology of the fusion bed, and local host factors. Vascularized grafts have higher success rates for union and can better overcome a poor fusion bed than nonvascular grafts. However, they are associated with higher donor site morbidity and greater technical difficulty. METHODS: Three patients with complex medical histories portending a difficult spinal fusion were treated with anterior arthrodesis using vascularized fibular autografts. Vascular patency was confirmed by bone scintigraphy, and osseous union by radiography and computed tomography. RESULTS: All patients had successful osseous fusion in 3 to 6 months. Deformity was improved. Patients reported decreased pain and resumption to previous activities at 24 months follow-up. There were no complications. CONCLUSIONS: A vascularized fibular graft is a useful alternative to standard grafts for spinal arthrodesis. Vascularized fibular grafts provide high fusion rates, rapid incorporation, and increased mechanical strength, and thus heal better in a suboptimal graft bed. The procedure is technically demanding, often requiring the expertise of a microvascular surgeon for obtaining the graft and achieving anastomosis. It is best suited in cases where significant difficulty in obtaining a spinal fusion is anticipated.

Adult↗

PubMed2001

Penetrating esophageal injuries: multicenter study of the American Association for the Surgery of Trauma.

OBJECTIVE: The purpose of this study was to define the period of time after which delays in management incurred by investigations cause increased morbidity and mortality. The outcome study is intended to correlate time with death from esophageal causes, overall complications, esophageal related complications, and surgical intensive care unit length of stay. METHODS: This was a retrospective multicenter study involving 34 trauma centers in the United States, under the auspices of the American Association for the Surgery of Trauma Multi-institutional Trials Committee over a span of 10.5 years. Patients surviving to reach the operating room (OR) were divided into two groups: those that underwent diagnostic studies to identify their injuries (preoperative evaluation group) and those that went immediately to the OR (no preoperative evaluation group). Statistical methods included Fisher's exact test, Student's T test, and logistic regression analysis. RESULTS: The study involved 405 patients: 355 male patients (86.5%) and 50 female patients (13.5%). The mean Revised Trauma Score was 6.3, the mean Injury Severity Score was 28, and the mean time interval to the OR was 6.5 hours. There were associated injuries in 356 patients (88%), and an overall complication rate of 53.5%. Overall mortality was 78 of 405 (19%). Three hundred forty-six patients survived to reach the OR: 171 in the preoperative evaluation group and 175 in the no preoperative evaluation group. No statistically significant differences were noted in the two groups in the following parameters: number of patients, age, Injury Severity Score, admission blood pressure, anatomic location of injury (cervical or thoracic), surgical management (primary repair, resection and anastomosis, resection and diversion, flaps), number of associated injuries, and mortality. Average length of time to the OR was 13 hours in the preoperative evaluation group versus 1 hour in the no preoperative evaluation group (p < 0.001). Overall complications occurred in 134 in the preoperative evaluation group versus 87 in the no preoperative evaluation group (p < 0.001), and 74 (41%) esophageal related complications occurred in the preoperative evaluation group versus 32 (19%) in the no preoperative evaluation group (p = 0.003). Mean surgical intensive care unit length of stay was 11 days in the preoperative evaluation group versus 7 days in the no preoperative evaluation group (p = 0.012). Logistic regression analysis identified as independent risk factors for the development of esophageal related complications included time delays in preoperative evaluation (odds ratio, 3.13), American Association for the Surgery of Trauma Organ Injury Scale grade >2 (odds ratio, 2.62), and resection and diversion (odds ratio, 4.47). CONCLUSION: Esophageal injuries carry a high morbidity and mortality. Increased esophageal related morbidity occurs with the diagnostic workup and its inherent delay in operative repair of these injuries. For centers practicing selective management of penetrating neck injuries and transmediastinal gunshot wounds, rapid diagnosis and definitive repair should be made a high priority.

Adolescent↗

PubMed2001

The 15-year evolution of an urban trauma center: what does the future hold for the trauma surgeon?

BACKGROUND: Safer cars, decreased violence, and nonoperative management have changed the trauma patient's nature. We evaluated changes in a Level I trauma center over 15 years and considered their effect on trauma surgeons. METHODS: From January 1985 through August 1999, 16,799 trauma registry patients were analyzed for mechanism of injury, Injury Severity Score, and procedures. RESULTS: Mean Injury Severity Score decreased from 15.9 to 10.7 and length of stay fell from 8.0 days to 5.9 days. There were significant decreases in penetrating trauma admissions and percentage of patients with Abbreviated Injury Scale score > 3 for head, chest, and abdomen. Frequency of craniotomy, thoracotomy, and laparotomy dropped dramatically. CONCLUSION: Significant decreases in injury severity, penetrating violence, and operations have occurred over 15 years. These changes will have profound effects on the practice of trauma surgeons and on surgical education.

Abdominal Injuries↗

PubMed1996

The ongoing challenge of retroperitoneal vascular injuries.

BACKGROUND: Retroperitoneal vascular injury remains one of the most frequent causes of death following abdominal trauma. A risk analysis of the association between potential outcome predictors and mortality following abdominal aorta and inferior vena cava injuries was performed. METHODS: Eighty-nine patients sustaining abdominal aortic or inferior vena cava injury were concurrently evaluated for a 10-year period and retrospectively reviewed. A multiple logistic regression model evaluated the following variables:presence of shock on admission, base deficit (< -10 or > or = -10), classification by the organ injury scale (OIS), blood transfusion, crystalloid infusion, total infusion volume, associated injuries, site of injury, and presence of retroperitoneal tamponade. RESULTS: Overall mortality for all injuries was 57%. Excluding all death on arrival (DOA) patients, the mortality rate decreased to 45.7%. Death following abdominal aortic injuries was significantly associated with free bleeding in the peritoneal cavity, acidosis, and an injury in the suprarenal location (OIS > 4). For inferior vena cava injuries and combined abdominal aortic and inferior vena cava injuries, death was associated with free bleeding, the suprarenal location (OIS = 4), and the presence of shock on admission as well. CONCLUSIONS: Despite advances in transport and resuscitation, mortality of aortic and vena cava injuries remains unchanged. Shock on admission, bleeding without retroperitoneal tamponade, acidosis, and the suprarenal location each play a significant role in mortality. Immediate identification associated with a rapid surgical approach are the only factors that may improve survival of such devastating injuries.

Adolescent↗

PubMed1996

Overlooked spine injuries associated with lumbar transverse process fractures.

Transverse process fractures of the lumbar spine often are considered benign fractures related to direct trauma or psoas muscle avulsion. Treatment of these usually stable injuries is primarily administered when the patient becomes symptomatic. However, significant force often is required to cause these injuries, and other injuries may occur concomitantly. For this study, all patients who presented with identified lumbar transverse process fractures were further evaluated radiographically with computed tomography for the detection of other possible spine injuries. Medical and radiology records of 28 consecutive patients who had plain radiographs and computed tomography scans taken of their lumbar spine were reviewed retrospectively; these patients presented with lumbar spine transverse process fractures between January 1, 1989 and June 30, 1992. Three of the 28 patients (11%) had a lumbar spine fracture that was identified by computed tomography but overlooked on plain radiographs. Approximately 11% of patients with major injuries may be misdiagnosed if only plain radiographs are used in the evaluation of transverse process fractures. Computed tomography scanning of all lumbar spine transverse process fractures resulting from acute trauma should be considered because this diagnostic measure decreases the risk of overlooking potentially serious injuries.

Diagnostic Errors↗

PubMed1996

Status of nonoperative management of blunt hepatic injuries in 1995: a multicenter experience with 404 patients.

INTRODUCTION: Nonoperative management is presently considered the treatment modality of choice in over 50% of adult patients sustaining blunt hepatic trauma who meet inclusion criteria. A multicenter study was retrospectively undertaken to assess whether the combined experiences at level I trauma centers could validate the currently reported high success rate, low morbidity, and virtually nonexistent mortality associated with this approach. Thirteen level I trauma centers accrued 404 adult patients sustaining blunt hepatic injuries managed nonoperatively over the last 5 years. Seventy-two percent of the injuries resulted from motor vehicle crashes. The mean injury severity score for the entire group was 20.2 (range, 4-75), and the American Association for the Surgery of Trauma-computerized axial tomography scan grading was as follows: grade I, 19% (n = 76); grade II, 31% (n = 124); grade III, 36% (n = 146); grade IV, 10% (n = 42); and grade V, 4% (n = 16). There were 27 deaths (7%) in the series, with 59% directly related to head trauma. Only two deaths (0.4%) could be attributed to hepatic injury. Twenty-one (5%) complications were documented, with the most common being hemorrhage, occurring in 14 (3.5%). Only 3 (0.7%) of these 14 patients required surgical intervention, 6 were treated by transfusions alone (0.5 to 5 U), 4 underwent angio-embolization, and 1 was further observed. Other complications included 2 bilomas and 3 perihepatic abscesses (all drained percutaneously). Two small bowel injuries were initially missed (0.5%), and diagnosed 2 and 3 days after admission. Overall, 6 patients required operative intervention: 3 for hemorrhage, 2 for missed enteric injuries, and 1 for persistent sepsis after unsuccessful percutaneous drainage. Average length of stay was 13 days. Nonoperative management of blunt hepatic injuries is clearly the treatment modality of choice in hemodynamically stable patients, irrespective of grade of injury or degree of hemoperitoneum. Current data would suggest that 50 to 80% (47% in this series) of all adult patients with blunt hepatic injuries are candidates for this form of therapy. Exactly 98.5% of patients analyzed in this study successfully avoided operative intervention. Bleeding complications are infrequently encountered (3.5%) and can often be managed nonoperatively. Although grades IV and V injuries composed 14% of the series, they represented 66.6% of the patients requiring operative intervention and thus merit constant re-evaluation and close observation in critical care units. The optimal time for follow-up computerized axial tomography scanning seems to be within 7 to 10 days after injury.

Adolescent↗

PubMed1990

Postburn immune suppression: an inflammatory response to the burn wound?

In an effort to elucidate the causes of immune suppression which follows severe burn injury, we studied the immunologic effects of subcutaneous implantation of burned skin, as well as implantation of other materials, in mice. Ten days following the implantation, splenic lymphocyte proliferation and lymphocyte surface expression of activation antigens (IL-2R and Ia) were analyzed following a 3-day culture period. In addition, peritoneal neutrophils were analyzed for oxidative burst activity using flow cytometry and a dye which reacts with intracellular hydrogen peroxide. Implantation of a 2 x 2 cm section of burned/unburned skin as well as implantation of a similar-sized piece of cotton gauze or collagen sheet resulted in subsequent suppression of both lymphocyte activation proliferation and neutrophil oxidative burst activity. An intense local inflammatory response to the burn wound may play a role leading to the profound systemic immune suppression which follows severe burn injury.

Animals↗

PubMed1989

Cholestatic effect of carmustine in rats.

A single i.p. dose of 20 mg/kg of carmustine [1,3-bis-(2-chloroethyl)-1-nitrosourea; BCNU] caused intrahepatic cholestasis in rats within 48 hr of administration. Cholestasis was characterized by a selective reduction of the bile salt independent fraction of bile flow. Increased plasma K+ and decreased plasma Na+ concentrations, consistent with this effect, were observed. Because bile: plasma osmolality and biliary bile salt concentrations were elevated, increased permeability to bile salts and other osmotically active solutes between bile and plasma is unlikely. Bile salt excretion was normal despite the reduced bile flow because biliary bile salt concentration was increased. In contrast, the treated rats were unable to concentrate bromosulfophthalein in bile before, during and after the onset of cholestasis. Because no reduction in hepatic perfusion was observed in vivo in BCNU-treated rats, reduced xenobiotic organic anion excretion may be a selective effect of the drug. The cholestatic effects of BCNU appear to be different from either alpha-naphthylisothiocyanate or estrogenic steroids.

Animals↗

PubMed1989

Effect of 1,3-bis-(2-chloroethyl)-1-nitrosourea on cholephilic dye metabolism and excretion in anesthetized rats.

The maximal biliary excretion of sulfobromophthalein (BSP) during constant i.v. infusion (2.5 mg/min/kg) was inhibited 45% in pentobarbital-anesthetized Sprague-Dawley rats, 48 hr after treatment with 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU; 20 mg/kg i.p.). Thirty-six to 48 hr after treatment, BCNU also inhibited the biliary excretion of an i.v. bolus of indocyanine green (24 mg/kg) by 75 to 85%. This suggested that inhibition of glutathione-S-transferase activity was not the main site of action of BCNU in its interference with cholephilic dye excretion. Indeed, it was found that conjugation of BSP with reduced glutathione (GSH) mediated by liver cytosol isolated from BCNU-pretreated rats was unaltered. In addition, BCNU did not deplete hepatic GSH. On the contrary, the hepatic concentration of GSH was increased by 60% 48 hr after treatment with BCNU. Thus, the ability of BCNU to block BSP excretion is probably not due to decreased conjugation of BSP with GSH. Inhibition of excretion under the saturating conditions of constant infusion strongly suggests an effect on canalicular excretion.

Anesthesia↗

PubMed1986

Immunomodulating drugs increase resistance against sepsis in traumatized mice.

Immune suppression occurs frequently after major injury and undoubtedly contributes to infection and mortality in trauma patients. Prevention of such suppression may lead to decreased infection and improved survival in trauma patients surviving the immediate insult of injury. Suppressor-cell activation appears to play a key role in immune suppression after major injury. For several years we have studied the effects on immune functions after injury of various drugs which have been shown in the immunologic literature to have inhibitory effects on suppressor cell populations. H2-antagonists may inhibit suppressor cell activation by blocking surface H2-receptors, which are present in higher numbers on suppressor cells than on helper cells. Prostaglandin inhibitors may block the multiple immune suppressive effects of prostaglandins, particularly PGE2. Immunological studies suggest that low-dose cyclophosphamide selectively inhibits the proliferation of suppressor T cells. Our previous work suggested that such drugs preserve cell-mediated immune functions after injury. In experiments reported here, we utilized a standard hindlimb crush injury and amputation in mice, followed in 24 hrs by polymicrobial septic challenge using cecal ligation and 23-gauge needle puncture (CLP). Nontraumatized (control) mice had a 36.2% mortality after CLP; when crush injury/amputation was followed by CLP in 24 hrs the mortality rose to 63.8% (p less than 0.0035). When mice were given 24 hrs before crush/amputation: cimetidine, an H2-antagonist (10 mg/kg/day); ibuprofen, a prostaglandin blocker (5 mg/kg/day); or cyclophosphamide (2.5 mg/kg/day), and a second dose on the day of trauma, with CLP 24 hrs later, subsequent mortality was not different from the mortality in nontraumatized, control mice (p less than 0.0035).(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗

PubMed1984

Impaired biliary excretion of taurocholate associated with increased biliary tree permeability in mirex- or chlordecone-pretreated rats.

Impaired biliary excretion of exogenously provided xenobiotic metabolites was demonstrated previously after pre-exposure of rats to mirex (MX) or chlordecone (CD). This toxicity was studied further in pentobarbital-anesthetized rats, cannulated at the common bile duct. We found reduced biliary excretion rates for exogenous [14C]taurocholic acid (3 or 10 mumol/kg bolus) after 15-day dietary pretreatment of male rats with 20 or 100 ppm of MX or CD. Hepatobiliary dysfunction was dose-dependent. Maximal reduction in excretory rate on a per gram of liver basis (50%) followed treatment with 100 ppm of MX. Biliary tree permeability was estimated to ascertain whether efflux of canalicular bile into the hepatic circulation explained hepatobiliary dysfunction. Bile-to-plasma concentration ratios for [3H]sucrose increased in parallel with MX- and CD-impaired biliary excretion. Modeling the relationship between bile flow and bile-to-plasma [3H]sucrose ratio indicated the site of increased permeability involved a paracellular pathway. Bile flow (on a per gram of liver basis) and biliary clearance of [14C]erythritol were both reduced by 100 ppm of these toxicants. The above effects occurred in the absence of substantial hepatocellular necrosis, whereas liver enlargement increased in a dose-dependent manner. Maximal liver enlargement (doubling of liver weight) resulted from 100 ppm of MX treatment. These results indicated that hepatobiliary dysfunction induced by MX and CD was at least partially explained by increased permeability of the biliary tree.

Animals↗

PubMed1983

Impact of choice of anesthetic with vagotomy testing.

Incomplete vagotomy is the most important cause of recurrent ulcer disease. Despite this, intraoperative vagotomy testing has not gained widespread acceptance. We used a technique with Congo red, a nontoxic azine dye that turns black (pH, 3.0) intraoperatively. The vagolytic effects of various general anesthetics has been shown. We found that halothane, used as a general anesthetic, combined with pentagastrin administration as a vagally synergistic stimulant, produced the most reliable, safe, and reproducible result when using Congo red intraoperatively.

Anesthesia, General↗

PubMedDate not supplied

Distal cervical spine evaluation using swimmer's flexion-extension radiographs.

Radiographic evaluation of the cervical spine begins with anteroposterior, lateral, and odontoid views. Unless the junction of C7-T1 can be adequately visualized on the cross-table lateral view, a swimmer's view is often performed. After fractures and subluxations have been excluded with these nonstressed views, spinal stability may be evaluated with stressed view radiographs such as a flexion-extension series. However, there is currently no protocol for evaluating the distal spinal stability in patients in whom traditional flexion-extension radiographs fail to visualize the important distal C7-T1 juncture. The present case study describes a trauma patient suffering from neck pain in whom cervical spine instability was ruled out using a swimmer's flexion-extension technique. Further study of this technique as a supplement to the conventional flexion and extension views in the stressed assessment of the entire cervical spine is recommended.

Adult↗

PubMedDate not supplied

Making the transition to topical anesthesia.

The transition to topical anesthesia and clear corneal cataract surgery can be made safe, effective, and less stressful through proper preparation and training as a surgical team. Sharing experiences with other practices will help in this process, as will visiting other practices and seeing them in action.

Administration, Topical↗