Biomedical subjects

R A Read

Publications and source records attributed to R A Read.

At least 37 records · Page 2Linked to original sources

PubMed1995

Epidemiology of trauma deaths: a reassessment.

OBJECTIVE: Recognizing the impact of the 1977 San Francisco study of trauma deaths in trauma care, our purpose was to reassess those findings in a contemporary trauma system. DESIGN: Cross-sectional. MATERIAL AND METHODS: All trauma deaths occurring in Denver City and County during 1992 were reviewed; data were obtained by cross-referencing four databases: paramedic trip reports, trauma registries, coroner autopsy reports and police reports. MEASUREMENTS AND MAIN RESULTS: There were 289 postinjury fatalities; mean age was 36.8 +/- 1.2 years and mean Injury Severity Score (ISS) was 35.7 +/- 1.2. Predominant injury mechanisms were gunshot wounds in 121 (42%), motorvehicle accidents in 75 (38%) and falls in 23 (8%) cases. Seven (2%) individuals sustained lethal burns. Ninety eight (34%) deaths occurred in the pre-hospital setting. The remaining 191 (66%) patients were transported to the hospital. Of these, 154 (81%) died in the first 48 hours (acute), 11 (6%) within three to seven days (early) and 26 (14%) after seven days (late). Central nervous system injuries were the most frequent cause of death (42%), followed by exsanguination (39%) and organ failure (7%). While acute and early deaths were mostly due to the first two causes, organ failure was the most common cause of late death (61%). CONCLUSIONS: In comparison with the previous report, we observed similar injury mechanisms, demographics and causes of death. However, in our experience, there was an improved access to the medical system, greater proportion of late deaths due to brain injury and lack of the classic trimodal distribution.

Accidents, Traffic↗

PubMed1995

Treatment of canine nictitans plasmacytic conjunctivitis with 0.2 per cent cyclosporin ointment.

Nictitans plasmacytic conjunctivitis, commonly referred to as plasma cell infiltrate of the nictitans or plasmoma, was diagnosed in 12 dogs (23 eyes) on the basis of clinical signs and nictitans conjunctival biopsy specimens. These dogs underwent a clinical therapeutic trial with twice daily 0.2 per cent cyclosporin ophthalmic ointment. Response to therapy was monitored over a six-week period and repeat biopsy specimens were then taken. Significant (P < 0.05) reductions between pre- and post trial scores were recorded for: mucopurulent ocular discharge quantity; degree of bulbar conjunctival hyperaemia; areas of nictitans hyperaemia, thickening and depigmentation. Schirmer tear test values significantly increased between the start and end of treatment. Biopsy specimens were subjected to selective detection procedures for plasma cells (methyl green-pyronin staining) and T lymphocytes (CD3 antigen labelling). Mean cell counts showed a significant reduction in plasma cell numbers, but the trend towards reduced T lymphocyte numbers was not significant.

Animals↗

PubMed1995

Distant abdominal and thoracic pedicle skin flaps for treatment of distal limb skin defects.

The treatment of large skin defects of the distal limbs of dogs and cats can be difficult due to the lack of skin available for primary wound closure or the creation of local skin flaps. Distant pedicle skin flaps provide an acceptable alternative for wound closure with full thickness skin and provide a cosmetic result. Fourteen animals (10 dogs and four cats) that had distant pedicle skin flaps are reviewed. The technique allowed 100 per cent wound coverage in 10 of 14 animals and greater than 95 per cent skin flap survival occurred in 12 to 14 animals. complications associated with the procedure were most commonly wound infection and partial suture line dehiscence, however these did not detract from the final outcome. Flap release was in one or two stages, however the outcomes did not appear to be affected by the release protocol.

Animals↗

PubMed1995

Cranial cruciate ligament rupture in the dog--a retrospective study comparing surgical techniques.

Three surgical techniques, grouped as intra-articular techniques, extracapsular techniques and fibular head transposition, were used for repair of the cranial cruciate ligament (CCL)-deficient stifle in 113 dogs over a 4 year 4 month period. The clinical outcome of the techniques were compared using information provided by the owners and physical examination. Regardless of surgical technique, 85.7 to 91.0% of dogs showed clinical improvement after surgery. However, less than 50% of dogs became clinically sound on the operated leg and 9.0 to 14.3% of dogs remained persistently lame on the operated leg. No statistical association was found between result after surgery and age, body weight, sex, duration of injury before surgery, association with injury, tibial plateau angle, degree of radiographic osteoarthritis before surgery or the presence of concurrent medial meniscal injury. On physical examination, extra-capsular techniques appeared superior to the fibular head transposition in terms of joint stability and limb function. Concurrent medial meniscal injury necessitating meniscectomy existed in 48.0% of cases. Twenty-two percent of dogs ruptured their contralateral CCL at an average of 14 months after the first.

Animals↗

PubMed1994

Early predictors of postinjury multiple organ failure.

OBJECTIVE: To find a predictive model for postinjury multiple organ failure (MOF). DESIGN: A 3-year cohort study ending December 1992 (first year: retrospective; last 2 years: prospective). SETTING: Denver General Hospital (Colo) is a regional level I trauma center. PATIENTS: Consecutive trauma patients with an Injury Severity Score (ISS) greater than 15, with an age greater than 16 years, and who survived longer than 24 hours. Stepwise logistic regression analysis was performed in all patients (n = 394), in the subgroup of patients with 0 to 12 hours, plus 12 to 24 hours base deficit (BD) results (n = 220), and in a second subgroup of patients with BD plus lactate results at 0 to 12 hours and 12 to 24 hours (n = 106). MAIN OUTCOME: Postinjury MOF. RESULTS: The following variables were identified as independent predictors of MOF in the analysis of all patients: age more than 55 years, ISS greater than or equal to 25, and more than 6 U of red blood cells in the first 12 hours after admission (U RBC/12 hours). In the subgroup with BD results, the same analysis identified age greater than 55 years, greater than 6 U RBC/12 hours, and BD greater than 8 mEq/L (0 to 12 hours), while in the last subgroup analysis including BD and lactate results, greater than 6 U RBC/12 hours, BD greater than 8 mEq/L (0 to 12 hours), and lactate greater than 2.5 mmol/L (12 to 24 hours) were independently associated with MOF. CONCLUSIONS: Age greater than 55 years, ISS greater than or equal to 25, and greater than 6 U RBC/12 hours are early independent predictors of MOF. Subgroup analyses indicate that BD and lactate levels may add substantial predictive value. Moreover, these results emphasize the predominant role of the initial insult in the pathogenesis of postinjury MOF.

Adolescent↗

PubMed1994

Cardiac enzymes are irrelevant in the patient with suspected myocardial contusion.

BACKGROUND: Myocardial contusion is commonly diagnosed following blunt chest trauma, and has potentially lethal complications. Cost-effective case management in patients with suspected myocardial contusion is confounded by the low incidence of complications and the lack of a reliable test to predict them. The clinical usefulness of elevated cardiac enzyme levels is controversial. METHODS: We analyzed a 4-year experience of 359 patients with high-risk blunt chest trauma who were assessed using an established practice guideline. Our multivariate statistical model evaluated all of the early risk factors included in the guideline, specifically focusing on cardiac enzyme levels. RESULTS: Myocardial contusion was diagnosed in 30% of patients, and complications (dysrhythmias and cardiogenic shock) occurred in 5%. In no case was cardiac enzyme elevation the sole predictor of a complication. The cost of routine cardiac enzyme assay was substantial. CONCLUSION: Cardiac enzyme determinations have no useful role in the evaluation of patients with suspected myocardial contusion. They should be eliminated from current practice guidelines.

Adolescent↗

PubMed1994

Gut ischemia/reperfusion produces lung injury independent of endotoxin.

OBJECTIVE: Bacterial translocation from the gut has been invoked as a common inciting event for postinjury multiple organ failure. We previously showed that gut ischemia/reperfusion induces remote organ injury. The purpose of this study was to ascertain if endotoxin has a pivotal mechanistic role in this process. DESIGN: Prospective, randomized study. SETTING: Animal laboratory. SUBJECTS: Sprague-Dawley rats weighing 300 to 350 g. INTERVENTIONS: Anesthetized animals underwent 45 mins of superior mesenteric artery occlusion and 2 hrs of reperfusion; sham laparotomy served as controls. Endotoxin was eliminated with the murine immunoglobulin (Ig) M antibody E5, 3 mg/kg i.v. before the study. MEASUREMENTS AND MAIN RESULTS: Plasma endotoxin was measured by the limulus amebocyte lysate assay. At 2 hrs of reperfusion, circulating neutrophil priming was determined by the difference in superoxide generation with and without the activating stimulus, N-formyl-Met-Leu-Phe. Neutrophil sequestration in the lung was quantitated by myeloperoxidase activity, and by lung endothelial permeability by 125I albumin lung/blood ratio. Endotoxin concentrations were not significantly (significance determined as p < .05) different between the gut ischemia/reperfusion and laparotomy groups (n = > or = 5) during ischemia or reperfusion. Circulating neutrophil priming, neutrophil accumulation in the lung, and lung injury were provoked by gut ischemia/reperfusion, but not altered by endotoxin elimination. CONCLUSION: Gut ischemia/reperfusion primes circulating neutrophils and produces lung injury by a mechanism independent of endotoxin.

Animals↗

PubMed1994

Trauma surgeons can render definitive surgical care for major thoracic injuries.

Restrictions on the operative domain of general surgeons threaten the viability of trauma surgery as a career choice. Our study hypothesis is that an experienced trauma surgeon can provide definitive care for life-threatening thoracic trauma. This analysis is based on clinical outcomes at an ACS-verified level I center in which there are more than 3000 trauma admissions managed annually under the direction of four academic trauma surgeons. We selected penetrating cardiac wounds and blunt tears of the thoracic aorta because these injuries are managed exclusively by the trauma service and the endpoints are distinct. During the past 4 years, 40 patients with cardiac wounds were delivered to the ED; 23 patients arrived dead. In the remaining 17, injury mechanisms were 15 stab wounds (SW), one gunshot wound (GSW), and one shotgun (SGW). Four of these patients required ED thoracotomy, and the remaining 13 underwent some form of prethoracotomy pericardial decompression. Survival rate without neurologic deficit was 94% (16 of 17). During this same period, 19 patients with a torn thoracic aorta from blunt injuries arrived with signs of life. In this group the injury mechanisms were automobile crash in 15, and the mean ISS was 39.7 +/- 2.3. One patient was transferred for total cardiopulmonary bypass; 17 of the remaining patients underwent aortic repair employing partial left heart bypass. Sixteen of our 18 patients lived and none developed paraplegia. In summary, excluding patients who arrived dead, survival for penetrating cardiac wounds was 94% and for blunt thoracic aortic tears 89%. In conclusion, these data support our contention that trauma surgeons can render definitive care for thoracic injuries with survival rates comparable to those reported by cardiothoracic surgeons.

Adolescent↗

PubMed1994

Lipopolysaccharide-induced CD11B-mediated neutrophil-endothelial adhesion is not required for polymorphonuclear cell priming.

Previous work has implicated both neutrophil-endothelial cell (PMN-EC) adhesion and PMN priming (enhanced superoxide production following activation) in the development of postinjury adult respiratory distress syndrome (ARDS) and multiple organ failure (MOF). CD11B, a member of the integrin family of PMN surface receptors, has been alleged to have a prominent role in these inflammatory PMN-EC processes. The purpose of the present study was to test the hypothesis that CD11B-mediated PMN-EC adhesion is necessary for endotoxin (LPS)-induced PMN priming. Human neutrophils, isolated by Percoll gradient centrifugation, were exposed to LPS (100 ng/mL). At fixed times over 120 minutes (a) superoxide following fMLP activation (i.e., priming), (b) PMN-EC adhesion, and (c) expression of CD11B were assayed. Superoxide production was measured by cytochrome c reduction, PMN-EC adhesion with indium-labelled PMN adherence to human umbilical vein endothelial cell (HUVEC) monolayer cultures, and CD11B expression with fluorescent labelled anti-CD11B (60.1) antibodies. The PMN-EC adhesion was biphasic, with an early maximum at 15 minutes followed by a nadir at 60 minutes and secondary rise through 120 minutes of LPS exposure. CD11B expression changed dramatically in temporal association with early PMN-EC adhesion, but the secondary increase in adhesion was associated with only a mild rise in CD11B expression. PMN priming increased after a latency of 15 minutes to a maximum of 800 nmol/10(6) cells/min after 60 minutes of LPS exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Adhesion↗

PubMed1993

Partial left heart bypass for thoracic aorta repair. Survival without paraplegia.

OBJECTIVE: Emergency repair of the torn descending thoracic aorta has been associated with an almost 15% incidence of paraplegia. The literature to date suggests that the incidence of paraplegia is not influenced by mechanical adjuncts to enhance distal aortic perfusion during cross-clamping and therefore, "clamp and sew" has been considered an acceptable technique. The purpose of the present study was to review our experience with repair of descending thoracic aortas using partial left heart bypass and to compare this favorable initial experience with the available data on the use of the heparinless centrifugal pump. DESIGN: A retrospective review of the routine use of partial left heart bypass in 16 consecutive patients with descending thoracic aorta disruptions. Results were compared with similar reports in the recent literature on trauma. SETTING: A level 1 trauma facility in the Denver, Colo, metropolitan area. PATIENTS: All patients with multisystem blunt trauma with a mean injury severity score of 36. INTERVENTION: Repair of the descending thoracic aorta disruption using partial left heart bypass with a heparinless centrifugal pump. MAIN OUTCOME MEASURES: Primary outcome measures were survival and paraplegia; other monitored variables included proximal and distal aortic pressure, flow rates, and oxygen transport. RESULTS: Among the 14 survivors (88%) there were no cases of paraplegia, and intraoperative hemodynamics and oxygen transport were well maintained with partial left heart bypass. This experience is added to the available reported data on the use of the centrifugal pump. In these additional 42 patients, the mortality rate was 7%, with no incidence of paraplegia. CONCLUSIONS: This collective experience failed to disclose a single case of paraplegia when partial left heart bypass was employed for repair of descending thoracic aorta. Moreover, the use of partial left heart bypass in this cohort of critically injured patients is associated with survival and perioperative morbidity rates comparable with the best recent reports of emergency thoracic aortic repair.

Abdominal Injuries↗

PubMed1993

Gut ischemia mediates lung injury by a xanthine oxidase-dependent neutrophil mechanism.

Neutrophils (PMNs) are believed to play a key role in the pathogenesis of postinjury adult respiratory distress syndrome. We have previously shown that gut ischemia/reperfusion (I/R) produces lung injury by a process that requires PMNs. More recently, we have shown that xanthine oxidase (XO) plays a role. The purpose of this study was to characterize the mechanistic sequencing of XO activity versus the PMN in this model of gut I/R-induced lung injury. Normal and XO-inactivated (tungsten enriched, molybdenum depleted diet) rats underwent 45 min of superior mesenteric artery occlusion. After 6 hr reperfusion, blood was sampled and gut and lungs harvested. Myeloperoxidase (MPO) was used to quantitate PMN presence in the gut and lungs, while circulating PMN priming was measured as the difference in superoxide production with and without the activating stimulus, fMLP. 125I-labeled albumin leak was used as a marker for lung endothelial permeability. We observed that the gut I/R increased gut MPO levels, primed circulating PMNs, increased lung MPO levels, and provoked distant lung leak. XO inactivation abolished gut MPO activity, attenuated circulating PMN priming, and blocked lung leak. In conclusion, XO plays a proximal role in the pathogenesis of remote organ injury following splanchnic hypoperfusion.

Animals↗

PubMed1993

Pneumonia: cause or symptom of postinjury multiple organ failure?

Recent studies have shown that selective gut decontamination can reduce the incidence of pneumonia, but this does not decrease multiple organ failure (MOF) or mortality. These findings have prompted the hypothesis that pneumonia is an inconsequential symptom of MOF. To test this, we prospectively evaluated 123 high-risk trauma patients (mean Injury Severity Score = 36.2 +/- 1.5). Organ dysfunction, scored daily according to a 12-point scale, ultimately developed in 28 (23%) patients. Major infections were diagnosed, based on strict criteria, in 59 patients (48%), and pneumonia developed in 52 patients (43%). Pneumonia was significantly associated with MOF (82% of patients with MOF versus 30% of patients without MOF, p < 0.0001). In 14 (50%) of the patients with MOF, pneumonia preceded a significant rise (greater than or equal to 3) in serial MOF scoring. Of note, 10 (71%) of these patients died. Among the remaining 14 patients with MOF, 10 developed pneumonia, but this was associated with a minimal increase (less than or equal to 2) in MOF scoring (3 patients died). These data, by temporal association with MOF scoring, implicate pneumonia in precipitating or significantly worsening organ failure in 50% of the patients who developed MOF.

Adolescent↗

PubMed1993

Moderate exercise exacerbates the osteoarthritic lesions produced in cartilage by meniscectomy: a morphological study.

Unilateral medial meniscectomy was performed on two groups of sheep. At 1 week post-operatively, one group (N = 5) underwent a regimen of moderate walking exercise (24 km/week), while the other group (N = 5) received no exercise. Two groups (N = 6 and 8) of unoperated sheep were used as exercised and unexercised controls for the respective meniscectomized groups. Six months post-surgery all groups were sacrificed and their knee joints were examined macroscopically using established scoring systems. In both groups, meniscectomy induced cartilage and bone changes typical of early hypertrophic osteoarthritis. However, meniscectomized animals subjected to the exercise program developed more severe cartilage lesions and osteophytes than their unexercised counterparts. While the cell density in femoral cartilage of the meniscectomized and exercised group was similar to controls, that of the meniscectomized but unexercised animals was higher. We conclude form these data that in this animal model exercise exacerbated the lesions induced in articular cartilage by meniscectomy.

Animals↗

PubMed1993

Medicare's resource-based relative value scale fee schedule portends a gloomy future for trauma surgery.

Medicare's resource-based relative value scale (RBRVS) fee schedule dramatically restructures physician reimbursement; providers of cognitive-based services are projected to gain at the expense of those with procedure-based services. In this study, we computed the impact of the new payment system for Medicare comparing trauma surgery to four other surgical specialties. Plastic surgery will see a 4% increase in revenue, but the other specialties will experience a cut (trauma, minus 14%; general, minus 4%; vascular, minus 5%; cardiothoracic, minus 10%). As expected, with the exception of plastic surgery, there was a decrease in procedure reimbursement (trauma, minus 13%; general, minus 12%; vascular, minus 8%; cardiothoracic, minus 10%). However, when analyzing cognitive services, trauma is the only group that will sustain a reduction. This is largely explained by the fact that trauma cognitive services are inpatient based, whereas the RBRVS fee schedule is biased toward outpatient cognitive services. In conclusion, the RBRVS fee schedule will challenge the economic stability of trauma surgeons. Because Medicare reform will set future standards for other forms of physician reimbursement, trauma system planners need to take a proactive role in this evolving process.

Cardiac Surgical Procedures↗

PubMed1993

Diagnosing pneumonia in mechanically ventilated trauma patients: endotracheal aspirate versus bronchoalveolar lavage.

We prospectively investigated the diagnostic value of semiquantitative (semiQC) and quantitative (QC) cultures of endotracheal aspirate (ETA) compared with QC of bronchoalveolar lavage (BAL) fluids in 18 mechanically ventilated trauma patients with clinical signs of pneumonia. The general agreement between QC of ETA and BAL was 89% when conventional cutoffs for the QC were used and 94% if the cutoffs were adjusted for previous antibiotic therapy. In all six patients whose clinical diagnoses of pneumonia were considered definite, both QC of ETA and QC of BAL were positive; however, standard semiQC of ETA showed comparable results in this group. On the contrary, in the 12 patients whose clinical diagnoses were uncertain, QC of BAL and ETA were negative in ten patients and in five (50%) of these, pneumonia was eventually excluded. Semiquantitative cultures of ETA were positive in all these patients. Five (28%) patients experienced a decrease in PaO2/FiO2 (> 15% of previous value) 2 hours after BAL, and in three (17%) this derangement persisted for 24 hours. These data suggest that BAL may be hazardous in mechanically ventilated trauma patients and that its use should be restricted to patients in whom the diagnosis is in doubt.

Adult↗

PubMed1993

Postinjury multiple organ failure: role of extrathoracic injury and sepsis in adult respiratory distress syndrome.

Adult respiratory distress syndrome (ARDS) and multiple organ failure (MOF) occur as a result of an unbridled systemic inflammatory response (i.e., severe systemic inflammatory response syndrome [SIRS]). Early epidemiologic studies concluded that infection with systemic sepsis was the common pathway for the development of ARDS and eventual MOF. As a consequence, research investigation from 1977 to 1987 focused on later clinical events (e.g., immunosuppression, persistent hypercatabolism, and bacterial translocation). Now, it is believed that an initial massive traumatic insult can create severe SIRS independent of infection (one-hit model). Alternatively, a less severe traumatic insult can create an inflammatory environment (i.e., primes the host) such that a later, otherwise innocuous, secondary inflammatory insult precipitates severe SIRS (two-hit model). As a result of these newer inflammatory models, research interest over the last 5 yrs has shifted to investigating earlier clinical events (e.g., unrecognized flow-dependent oxygen consumption, ischemia/reperfusion, and priming/activation of the inflammatory response). The traditional infection models of ARDS and MOF are applicable to current research and patient care efforts. However, the inflammatory models emphasize the pivotal role of the initial traumatic insult. Moreover, while ARDS occurs earlier than other types of overt organ failure, it is now believed that simultaneous organ injury is occurring, presumably via similar inflammatory mechanisms.

Adult↗

PubMed1993

Platelet-activating factor-induced polymorphonuclear neutrophil priming independent of CD11b adhesion.

BACKGROUND: Our previous studies have implicated phospholipase A2-dependent platelet-activating factor (PAF) production in the genesis of polymorphonuclear neutrophil (PMN)-mediated tissue injury after gut ischemia-reperfusion. Further, these studies have suggested a discordance of PMN sequestration and tissue injury. CD11B-dependent PMN-endothelial cell adhesion has been purported to play a dominant role in PMN-mediated tissue injury. We therefore undertook this study with the hypothesis that PAF-induced PMN superoxide production requires CD11B-mediated PMN-endothelial cell adherence. METHODS: Human PMNs, isolated by Percoll gradient centrifugation, were exposed to PAF (10 ng/ml). At fixed times of exposure during 120 minutes, (1) superoxide production, (2) CD11B receptor expression, and (3) PMN adhesion to unstimulated human umbilical vein endothelial cell cultures were assayed. RESULTS: PAF induced prompt changes in PMN priming (increased superoxide production after N-formyl-methyl-leucyl-phenylalanine activation), adhesion to unstimulated endothelial cells, and CD11B receptor expression. Priming was temporally concordant with the rise and fall of CD11B expression but appeared to precede adhesion. CD11B blockade (F(Ab') 2 anti-CD11B [60.1] antibodies), before or at maximal PAF priming, reduced PMN adhesion but had no effect on superoxide production. CONCLUSIONS: In summary, PAF-induced PMN priming occurs in temporal concordance with the expression of CD11B and subsequent endothelial cell adherence, but CD11B-mediated adherence is not essential for this process.

Cell Adhesion↗

PubMed1993

Intravascular ultrasonography for the diagnosis of traumatic aortic disruption: a case report.

Thoracic aortic disruptions after blunt trauma are highly lethal injuries. Diagnosis of these injuries has traditionally been based on clinical suspicion, chest radiographs, and aortography. The roles of dynamic computed tomography and transesophageal echocardiography are currently under investigation. Intravascular ultrasonography is a new technology with potential as a diagnostic adjunct in the evaluation of these injuries. We present a case of traumatic aortic disruption identified by intravascular ultrasonography after nondiagnostic aortography and dynamic computed tomography studies.

Accidents, Traffic↗