MEDB-74. Serial assessment of measurable residual disease in medulloblastoma liquid biopsies

Nearly one-third of children with medulloblastoma, a malignant embryonal tumor of the cerebellum, succumb to their disease. Conventional response monitoring by imaging and cerebrospinal fluid (CSF) cytology remains challenging and a marker for measurable residual disease (MRD) is lacking. Here, we show the clinical utility of CSF-derived cell-free DNA (cfDNA) as a biomarker of MRD in serial samples collected from children with medulloblastoma (123 patients, 476 samples) enrolled on a prospective trial. Using low-coverage whole-genome sequencing, tumor-associated copy-number variations (CNVs) in CSF-derived cfDNA are investigated as an MRD surrogate. MRD is detected at baseline in 85% and 54% of patients with metastatic and localized disease, respectively. The number of MRD-positive patients decline with therapy, yet those with persistent MRD have significantly higher risk of progression. Importantly, MRD detection precedes radiographic progression in half who relapse. Our findings advocate for the prospective assessment of CSF-derived liquid biopsies in future trials for medulloblastoma.

Clinical impact of combined epigenetic and molecular analysis of pediatric low-grade gliomas

BACKGROUND

Both genetic and methylation analysis have been shown to provide insight into the diagnosis and prognosis of many brain tumors. However, the implication of methylation profiling and its interaction with genetic alterations in pediatric low-grade gliomas (PLGGs) are unclear.

METHODS

We performed a comprehensive analysis of PLGG with long-term clinical follow-up. In total 152 PLGGs were analyzed from a range of pathological subtypes, including 40 gangliogliomas. Complete molecular analysis was compared with genome-wide methylation data and outcome in all patients. For further analysis of specific PLGG groups, including BRAF p.V600E mutant gliomas, we compiled an additional cohort of clinically and genetically defined tumors from 3 large centers.

RESULTS

Unsupervised hierarchical clustering revealed 5 novel subgroups of PLGG. These were dominated by nonneoplastic factors such as tumor location and lymphocytic infiltration. Midline PLGG clustered together while deep hemispheric lesions differed from lesions in the periphery. Mutations were distributed throughout these location-driven clusters of PLGG. A novel methylation cluster suggesting high lymphocyte infiltration was confirmed pathologically and exhibited worse progression-free survival compared with PLGG harboring similar molecular alterations (P = 0.008; multivariate analysis: P = 0.035). Although the current methylation classifier revealed low confidence in 44% of cases and failed to add information in most PLGG, it was helpful in reclassifying rare cases. The addition of histopathological and molecular information to specific methylation subgroups such as pleomorphic xanthoastrocytoma-like tumors could stratify these tumors into low and high risk (P = 0.0014).

CONCLUSION

The PLGG methylome is affected by multiple nonneoplastic factors. Combined molecular and pathological analysis is key to provide additional information when methylation classification is used for PLGG in the clinical setting.

MBCL-21. GERMLINE ELONGATOR MUTATIONS IN SONIC HEDGEHOG MEDULLOBLASTOMA

BACKGROUND

Our previous analysis of established cancer predisposition genes in medulloblastoma (MB) identified pathogenic germline variants in ~5% of all patients. Here, we extended our analysis to include all protein-coding genes.

METHODS

Case-control analysis performed on 795 MB patients against >118,000 cancer-free children and adults was performed to identify an association between rare germline variants and MB.

RESULTS

Germline loss-of-function variants of Elongator Complex Protein 1 (ELP1; 9q31.3) were strongly associated with SHH subgroup (MB_SHH). ELP1-associated-MBs accounted for ~15% (29/202) of pediatric MB_SHH cases and were restricted to the SHHα subtype. ELP1-associated-MBs demonstrated biallelic inactivation of ELP1 due to somatic chromosome 9q loss and most tumors exhibited co-occurring somatic PTCH1 (9q22.32) alterations. Inheritance was verified by parent-offspring sequencing (n=3) and pedigree analysis identified two families with a history of pediatric MB. ELP1-associated-MB_SHH were characterized by desmoplastic/nodular histology (76%; 13/17) and demonstrated a favorable clinical outcome when compared to TP53-associated-MB_SHH (5-yr OS 92% vs 20%; p-value=1.3e-6) despite both belonging to the SHHα subtype. ELP1 is a subunit of the Elongator complex, that promotes efficient translational elongation through tRNA modifications at the wobble (U₃₄) position. Biochemical, transcriptional, and proteomic analyses revealed ELP1-associated-MBs exhibit destabilization of the core Elongator complex, loss of tRNA wobble modifications, codon-dependent translational reprogramming, and induction of the unfolded protein response.

CONCLUSIONS

We identified ELP1 as the most common MB predisposition gene, increasing the total genetic predisposition for pediatric MB_SHH to 40%. These results mark MB_SHH as an overwhelmingly genetically-predisposed disease and implicate disruption of protein homeostasis in MB_SHH development.

Therapeutic and Prognostic Implications of BRAF V600E in Pediatric Low-Grade Gliomas

Purpose BRAF V600E is a potentially highly targetable mutation detected in a subset of pediatric low-grade gliomas (PLGGs). Its biologic and clinical effect within this diverse group of tumors remains unknown. Patients and Methods A combined clinical and genetic institutional study of patients with PLGGs with long-term follow-up was performed (N = 510). Clinical and treatment data of patients with BRAF V600E mutated PLGG (n = 99) were compared with a large international independent cohort of patients with BRAF V600E mutated-PLGG (n = 180). Results BRAF V600E mutation was detected in 69 of 405 patients (17%) with PLGG across a broad spectrum of histologies and sites, including midline locations, which are not often routinely biopsied in clinical practice. Patients with BRAF V600E PLGG exhibited poor outcomes after chemotherapy and radiation therapies that resulted in a 10-year progression-free survival of 27% (95% CI, 12.1% to 41.9%) and 60.2% (95% CI, 53.3% to 67.1%) for BRAF V600E and wild-type PLGG, respectively ( P < .001). Additional multivariable clinical and molecular stratification revealed that the extent of resection and CDKN2A deletion contributed independently to poor outcome in BRAF V600E PLGG. A similar independent role for CDKN2A and resection on outcome were observed in the independent cohort. Quantitative imaging analysis revealed progressive disease and a lack of response to conventional chemotherapy in most patients with BRAF V600E PLGG. Conclusion BRAF V600E PLGG constitutes a distinct entity with poor prognosis when treated with current adjuvant therapy.

Abstract 5352: Optimization of library and enrichment procedures for RNASeq using RNA from formalin fixed paraffin embedded tissue

Large repositories of diagnostic formalin-fixed, paraffin-embedded (FFPE) tissue remain underutilized for transcriptome sequence analysis due to degradation of the RNA from the fixation process, which makes the samples unsuitable for traditional mRNA sequencing (mRNASeq). The use of random primers to generate cDNA, and biotinylated exon baits to enrich for coding regions allows for the generation of RNASeq data, but still yields data of variable quality, in part due to differences in FFPE sample processing. We performed a systematic analysis to determine which aspects of library construction and the enrichment process can be optimized to provide the best RNASeq data from FFPE samples.

The TruSeq RNA Access Library Prep Kit (Illumina) protocol was selected to evaluate optimization procedures for RNASeq from FFPE material. RNA was isolated from FFPE tissue using the Maxwell automated system (Promega). RNA libraries were also prepared with RNA extracted from frozen tissue of the matching samples using the TruSeq V2 mRNASeq Library Prep Kit (Illumina) for a comparison of exon coverage metrics. Samples derived from different types of pediatric cancer were selected for evaluation, including 2 low-grade gliomas, 2 ependymomas, 9 melanomas and 1 Ewing sarcoma. All of the FF tumor samples selected contained oncogenic gene fusions, previously identified by analysis of mRNASeq data. The parameters investigated included the initial amount of RNA input (10ng-400ng), library amplification PCR cycle number (9 cycles-15 cycles), and the duration of time for exon probe hybridization (1.5 hours vs 16 hours). The quality of the data was based on the overall library complexity and exon coverage. The complexity of the sequencing was measured using duplication rate (DupRate) defined as a library inserts from different sequence reads mapping to the same location in the reference genome; while the coverage was measured using the percentage of coding bases with coverage &gt;=20x (PCB20x).

Using the RNA Access protocol, we found that the PCB20x metrics were comparable between the FFPE samples and matched FF mRNASeq controls under the non-optimized conditions of 20ng of RNA input, 1.6 hour hybridization, and 15 cycles of PCR for library amplification. However, optimizing the protocol by increasing the input of RNA to 400ng, reducing the PCR to between 9-11 cycles, and extending the hybridization time to 16 hours increased library diversity, reduced the DupRate from greater than 80% to less than 44%, and increased coding region coverage PCB20x by at least 10%. All expected gene fusions identified in the RNASEQ data from the FF samples were also detected in the FFPE samples.

We have shown that increasing RNA input, reducing PCR cycles and extending the length of hybridization can significantly improve data quality and maximize library diversity, allowing for greater utilization of archival FFPE material for RNASeq.

Citation Format: Ji Wen, Ying Shao, Ruth Tatevossian, Yongjin Li, David W. Ellison, Gang Wu, Jinghui Zhang, John B. Easton. Optimization of library and enrichment procedures for RNASeq using RNA from formalin fixed paraffin embedded tissue [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5352. doi:10.1158/1538-7445.AM2017-5352

Molecular Classification of Ependymal Tumors across All CNS Compartments, Histopathological Grades, and Age Groups

Ependymal tumors across age groups are currently classified and graded solely by histopathology. It is, however, commonly accepted that this classification scheme has limited clinical utility based on its lack of reproducibility in predicting patients' outcome. We aimed at establishing a uniform molecular classification using DNA methylation profiling. Nine molecular subgroups were identified in a large cohort of 500 tumors, 3 in each anatomical compartment of the CNS, spine, posterior fossa, supratentorial. Two supratentorial subgroups are characterized by prototypic fusion genes involving RELA and YAP1, respectively. Regarding clinical associations, the molecular classification proposed herein outperforms the current histopathological classification and thus might serve as a basis for the next World Health Organization classification of CNS tumors.

Molecular characterization of choroid plexus tumors reveals novel clinically relevant subgroups

PURPOSE

To investigate molecular alterations in choroid plexus tumors (CPT) using a genome-wide high-throughput approach to identify diagnostic and prognostic signatures that will refine tumor stratification and guide therapeutic options.

EXPERIMENTAL DESIGN

One hundred CPTs were obtained from a multi-institutional tissue and clinical database. Copy-number (CN), DNA methylation, and gene expression signatures were assessed for 74, 36, and 40 samples, respectively. Molecular subgroups were correlated with clinical parameters and outcomes.

RESULTS

Unique molecular signatures distinguished choroid plexus carcinomas (CPC) from choroid plexus papillomas (CPP) and atypical choroid plexus papillomas (aCPP); however, no significantly distinct molecular alterations between CPPs and aCPPs were observed. Allele-specific CN analysis of CPCs revealed two novel subgroups according to DNA content: hypodiploid and hyperdiploid CPCs. Hyperdiploid CPCs exhibited recurrent acquired uniparental disomy events. Somatic mutations in TP53 were observed in 60% of CPCs. Investigating the number of mutated copies of p53 per sample revealed a high-risk group of patients with CPC carrying two copies of mutant p53, who exhibited poor 5-year event-free (EFS) and overall survival (OS) compared with patients with CPC carrying one copy of mutant p53 (OS: 14.3%, 95% confidence interval, 0.71%-46.5% vs. 66.7%, 28.2%-87.8%, respectively, P = 0.04; EFS: 0% vs. 44.4%, 13.6%-71.9%, respectively, P = 0.03). CPPs and aCPPs exhibited favorable survival.

DISCUSSION

Our data demonstrate that differences in CN, gene expression, and DNA methylation signatures distinguish CPCs from CPPs and aCPPs; however, molecular similarities among the papillomas suggest that these two histologic subgroups are indeed a single molecular entity. A greater number of copies of mutated TP53 were significantly associated to increased tumor aggressiveness and a worse survival outcome in CPCs. Collectively, these findings will facilitate stratified approaches to the clinical management of CPTs.

Comparative expression analysis reveals lineage relationships between human and murine gliomas and a dominance of glial signatures during tumor propagation in vitro

Brain tumors are thought to originate from stem/progenitor cell populations that acquire specific genetic mutations. Although current preclinical models have relevance to human pathogenesis, most do not recapitulate the histogenesis of the human disease. Recently, a large series of human gliomas and medulloblastomas were analyzed for genetic signatures of prognosis and therapeutic response. Using a mouse model system that generates three distinct types of intrinsic brain tumors, we correlated RNA and protein expression levels with human brain tumors. A combination of genetic mutations and cellular environment during tumor propagation defined the incidence and phenotype of intrinsic murine tumors. Importantly, in vitro passage of cancer stem cells uniformly promoted a glial expression profile in culture and in brain tumors. Gene expression profiling revealed that experimental gliomas corresponded to distinct subclasses of human glioblastoma, whereas experimental supratentorial primitive neuroectodermal tumors (sPNET) correspond to atypical teratoid/rhabdoid tumor (AT/RT), a rare childhood tumor.

High incidence of hearing loss in long-term survivors of multisystem Langerhans cell histiocytosis

BACKGROUND

Ear involvement in the acute phase of Langerhans cell histiocytosis (LCH) is commonly seen and well documented, but the long-term sequelae are less well described, particularly in relation to hearing loss.

METHODS

We investigated 40 patients with biopsy-proven multisystem LCH >5 years from the end of treatment, using detailed audiological assessment and CT/MRI imaging of the petrous temporal bones.

RESULTS

The incidence of ear involvement in the acute phase of disease was 70%. Fifteen of the 39 patients tested (38%) had residual permanent hearing loss at long-term follow-up.

CONCLUSIONS

The incidence of hearing loss is much higher than has previously been reported in LCH, and may reflect a referral bias of young (<2 years) and more complex patients to our tertiary centre. However, the hearing loss appears to be highly specific to this patient group when compared to other long-term survivors of childhood cancers, probably due to the propensity of LCH to involve the ears. We therefore recommend audiology testing as an important part of long-term follow-up for patients with multisystem LCH.

Thyrotoxicosis after matched unrelated bone marrow transplantation

Acquired hyperthyroidism is most commonly autoimmune in etiology. In the setting of allogeneic bone marrow transplantation (BMT), the use of radiotherapy (total body irradiation) as part of the regimen prior to BMT is known to cause endocrine dysfunction, especially hypopituitarism and hypothyroidism, but hyperthyroidism is rare. The authors report this unusual and late complication in a young boy after BMT for relapsed childhood lymphoblastic leukemia and discuss the possible etiologies.

Penetrating trauma in patients older than 55 years: a case-control study

BACKGROUND

Multiple studies have compared young and elderly blunt trauma patients, and concluded that, because elderly patients have outcomes similar to young patients, aggressive resuscitation should be offered regardless of age. Similar data on penetrating trauma patients are limited.

STUDY DESIGN

In a retrospective review, 79 patients with penetrating injuries and age > or =55 were blindly matched for Injury Severity Score (ISS) and Abbreviated Injury Scores (AIS) with 79 penetrating trauma patients aged 15-35 years, who were admitted to the hospital over the same 4 year period (June 1994-June 1998). Mortality rates and length of stay in the intensive care unit (ICU) and the hospital were compared between the two groups.

RESULTS

The average ISS for all patients was 12 (range 1-75) and identical for both groups. Both groups had similar injuries and were evaluated by an equal number and type of diagnostic studies. The mean ISS was not different between severely injured older and younger patients who required ICU admission or died. Among 32 nonsurvivors (18 older and 14 younger), older patients were more likely than younger patients to present with normal vital signs, although the comparison did not reach statistical significance (50% vs. 13%, P=0.25). There was a clinically significant trend for longer ICU (15+/-30 vs. 3+/-2 days, P=0.096) and hospital stay (10+/-18 vs. 6+/-8 days, P=0.08) among older patients, but mortality rates were similar (23% in older vs. 18% in younger, P=NS). Furthermore, these outcome parameters showed no difference when both groups were classified according to severity of injury or physiologic response.

CONCLUSIONS

Following penetrating trauma, older patients arriving alive and admitted to the hospital are as likely to survive as younger patients who have injuries of similar severity, but at the expense of longer ICU and hospital stays.

Endpoints of resuscitation of critically injured patients: normal or supranormal? A prospective randomized trial

OBJECTIVE

To evaluate the effect of early optimization in the survival of severely injured patients.

SUMMARY BACKGROUND DATA

It is unclear whether supranormal ("optimal") hemodynamic values should serve as endpoints of resuscitation or simply as markers of the physiologic reserve of critically injured patients. The failure of optimization to produce improved survival in some randomized controlled trials may be associated with delays in starting the attempt to reach optimal goals. There are limited controlled data on trauma patients.

METHODS

Seventy-five consecutive severely injured patients with shock resulting from bleeding and without major intracranial or spinal cord trauma were randomized to resuscitation, starting immediately after admission, to either normal values of systolic blood pressure, urine output, base deficit, hemoglobin, and cardiac index (control group, 35 patients) or optimal values (cardiac index >4.5 L/min/m2, ratio of transcutaneous oxygen tension to fractional inspired oxygen >200, oxygen delivery index >600 mL/min/m2, and oxygen consumption index >170 mL/min/m2; optimal group, 40 patients). Initial cardiac output monitoring was done noninvasively by bioimpedance and, subsequently, invasively by thermodilution. Crystalloids, colloids, blood, inotropes, and vasopressors were used by predetermined algorithms.

RESULTS

Optimal values were reached intentionally by 70% of the optimal patients and spontaneously by 40% of the control patients. There was no difference in rates of death (15% optimal vs. 11% control), organ failure, sepsis, or the length of intensive care unit or hospital stay between the two groups. Patients from both groups who achieved optimal values had better outcomes than patients who did not. The death rate was 0% among patients who achieved optimal values compared with 30% among patients who did not. Age younger than 40 years was the only independent predictive factor of the ability to reach optimal values.

CONCLUSIONS

Severely injured patients who can achieve optimal hemodynamic values are more likely to survive than those who cannot, regardless of the resuscitation technique. In this study, attempts at early optimization did not improve the outcome of the examined subgroup of severely injured patients.

Fetal death after trauma in pregnancy

Trauma in pregnancy places the mother and fetus at risk. The objective of this study is to identify risk factors independently associated with acute termination of pregnancy and/or fetal mortality after trauma. The medical and trauma registry records of 80 injured pregnant patients were reviewed. Data were collected and then analyzed by univariate and multivariate analysis. Three patients died (3.7%), 23 had the pregnancy acutely terminated (30%), and 14 suffered fetal death (17.5%). The only independent risk factors for fetal mortality were an Injury Severity Score (ISS) > or =9 and a nonviable pregnancy (<23 weeks). The combination of both risk factors increased the likelihood of fetal mortality by fivefold over that of patients without either risk factor. Maternal hemodynamic parameters did not predict fetal loss. Two patients lost their fetuses despite insignificant trauma (ISS = 1) and normal hemodynamic parameters, whereas eight delivered normal babies despite major trauma (ISS > or = 16). Hemodynamic stability on admission does not predict fetal mortality. Although the presence of moderate to severe injuries (ISS > or = 9) increases the likelihood of fetal mortality, this complication may occur even with insignificant trauma. Close maternal and fetal monitoring is justified, regardless of maternal hemodynamic presentation or severity of injury.

High-frequency percussive ventilation improves oxygenation in patients with ARDS

STUDY OBJECTIVES

To evaluate changes in respiratory and hemodynamic function of patients with ARDS and requiring high-frequency percussive ventilation (HFPV) after failure of conventional ventilation (CV).

DESIGN

Retrospective case series.

SETTING

Surgical ICU (SICU) and medical ICU (MICU) of an academic county facility.

MEASUREMENTS AND RESULTS

Thirty-two consecutive patients with ARDS (20 from SICU, 12 from MICU) who were unresponsive to at least 48 h of CV and were switched to HFPV were studied. Data on respiratory and hemodynamic parameters were collected during the 48 h preceding and the 48 h after institution of HFPV and compared. Between the period of CV and the period of HFPV, the ratio of PaO2 to the fraction of inspired oxygen (F(IO2)) increased ([mean+/-SE] 130+/-8 vs. 172+/-17; p = 0.027), peak inspiratory pressure (PIP) decreased (39.5+/-1.7 vs. 32.5+/-1.9 mm Hg; p = 0.002), and mean airway pressure(MAP) increased (19.2+/-1.2 vs. 27.5+/-1.4 mm Hg; p<0.001). The rate of change of PaO2/F(IO2) per hour was also significantly improved between the two periods. The same changes in PaO2/F(IO2), PIP, and MAP were observed when the last value recorded while the patients were on CV was compared with the first value recorded after 1 h of HFPV. This improvement was sustained but not amplified during the hours of HFPV. The patterns of improvement in these three parameters were similar in SICU and MICU patients as well as in volume-control and pressure-control patients. There were no changes in hemodynamic parameters.

CONCLUSION

The HFPV improves oxygenation by increasing MAP and decreasing PIP. This improvement is achieved soon after institution of HFPV and is maintained without affecting hemodynamics.

The "seat belt mark" sign: a call for increased vigilance among physicians treating victims of motor vehicle accidents

The use of seat belts is shown to cause a specific pattern of internal injuries. Skin bruise corresponding to the site of the seat belt is known as the "seat belt mark" (SBM) sign and is associated with a high incidence of significant organ injuries. No study has yet defined the exact incidence of injuries requiring intervention at the presence of this sign. The objective of this study was to find the incidence of surgically correctable injuries in belted car occupants with a SBM sign and to define strategies of early detection and treatment of such injuries. The prospective study included consecutive patients involved in road traffic accidents who were admitted at an academic Level I trauma center. Of 650 car occupants, 410 (63%) were restrained and 77 (12%) had a SBM across the abdomen, chest or neck. The injuries of these 77 patients were compared with the injuries of belted patients without an SBM sign. Of patients with SBMs, 9 per cent had neck bruises, 32 per cent had chest bruises, 40 per cent had abdominal bruises, and 19 per cent had bruises in multiple sites. No significant neck injuries were detected. Three patients were found to have myocardial contusion, and 10 patients had intra-abdominal injuries (predominantly bowel and mesenteric lacerations) requiring laparotomy. There was a near 4-fold increase in thoracic trauma (22.5% versus 6%; P=0.01) and a near 8-fold increase in intra-abdominal trauma (23% versus 3%; P < 0.0001) between the groups of patients with and without SBMs. The presence of the SBM sign should alert the physician to the high likelihood of specific internal injuries. Routine laparotomy or mandatory evaluation by specific diagnostic tests is not justified; rather, a high index of suspicion with a low threshold for appropriate diagnostic evaluation and/or surgical exploration should be maintained for the optimal management of such patients.

Predicting the need for thoracoscopic evacuation of residual traumatic hemothorax: chest radiograph is insufficient

BACKGROUND

The early removal of large residual posttraumatic hemothorax by videothoracoscopy is increasingly used to avoid the late sequelae of trapped lung and empyema. Plain chest radiography (CXR) is the tool most frequently used to select such cases for operation. Our recent experience has demonstrated that what appears to be a large retained hemothorax on CXR may turn out to be intrapulmonary or extrapleural conditions not amenable to thoracoscopic removal. Our objective was to evaluate the accuracy of CXR in detecting significant residual hemothorax and compare its clinical value to thoracic computed tomography (CT) when used to select patients for thoracoscopic evacuation.

METHODS

All patients requiring tube thoracostomy for traumatic hemothorax were prospectively evaluated during a 22-month period (n = 703). Patients who, on the second day after admission, demonstrated opacification on CXR involving more than the costophrenic angle were evaluated by thoracic computed tomography for the presence of undrained fluid. Second-day CXR (CXR2) results were compared with the CT findings. Incorrect interpretation was defined as a difference of more than 300 mL between the two readings. All CXR2 and CT results were reviewed in the same fashion by a radiologist blinded to the surgeon's interpretations. Data on injury mechanism, hemodynamic status, laboratory values, interventions, and outcome were collected prospectively.

RESULTS

Fifty-eight patients had clinically significant opacifications on CXR2. The surgeon's and radiologist's CXR2 interpretations were incorrect in 48 and 47% of the cases, respectively. The CT interpretations by the two specialists were in agreement in 97% of the cases. Management that would have been instituted on the basis of CXR2 findings was changed in 18 cases (31%). Twelve patients (21%) required early thoracoscopic evacuation of undrained collections. There was good correlation between the CT estimation and the thoracoscopically retrieved amount of blood.

CONCLUSION

Although CXR is useful as a screening tool, it cannot be used to reliably select patients for surgical evacuation of retained traumatic hemothorax. Decision-making should be based on thoracic CT findings.

Inability of an aggressive policy of thromboprophylaxis to prevent deep venous thrombosis (DVT) in critically injured patients: are current methods of DVT prophylaxis insufficient?

BACKGROUND

Deep venous thrombosis (DVT) in severely injured patients is a life-threatening complication. Effective and safe thromboprophylaxis is highly desirable to prevent DVT. Low-dose heparin (LDH) and sequential compression device (SCDs) are the most frequently used methods. Inappropriate use of these methods because of the nature or site of critical injuries (eg, brain lesion, solid visceral or retroperitoneal hematoma, extremity fractures) may lead to failure of DVT prophylaxis.

STUDY DESIGN

A prospective study was performed to evaluate the efficacy of a policy of aggressive use of LDH and SCDs in patients who are at very high risk for DVT. From January 1996 to August 1997, 200 critically injured patients were followed by weekly Doppler examinations to detect DVT at the proximal lower extremities. Only 3 patients did not receive any thromboprophylaxis. SCDs were applied in 97.5% and LDH was administered to 46% of the patients; 45% had both.

RESULTS

DVT was found in 26 patients (13%). The majority (58%) developed DVT within the first 2 weeks, but new cases were found as late as 12 weeks after admission. The incidence of DVT was the same among patients who had SCDs only or a combination of LDH and SCDs. Mechanism of injury, type and number of operations, site of injury, Injury Severity Score, and the incidence of femoral lines were not different between patients with and without DVT. Differences were found in the severity of injury to the chest and the extremities and the need for high-level respiratory support. Patients with DVT had prolonged ICU and hospital stays (on average, 34 and 49 days, respectively) and a high mortality rate (31%).

CONCLUSIONS

The incidence of DVT remains high among severely injured patients despite aggressive thromboprophylaxis. A combination of LDH and an SCD showed no advantage over SCD alone in decreasing DVT rates. Risk factors in this group of patients who are already at very high risk are hard to detect; Doppler examinations are justified for surveillance in all critically injured patients. Current methods of thromboprophylaxis seem to offer limited efficacy, and the search for more effective methods should continue.

Is there a limit to massive blood transfusion after severe trauma?

OBJECTIVE

To examine the hypothesis that the futility of short-term care for trauma patients requiring emergency operation can be determined based on the number of units of blood transfused and associated risk factors.

DESIGN

A 4-year retrospective review of a cohort of critically injured patients who underwent an emergency operation.

SETTING

A large-volume, academic level I, urban trauma center.

PATIENTS

One hundred forty-one consecutive patients received massive blood transfusions of 20 U or more of blood during preoperative and intraoperative resuscitation (highest, 68 U). There were 43 survivors (30.5%) and 98 nonsurvivors (69.5%).

MAIN OUTCOME MEASURES

Mortality.

RESULTS

The number of blood units transfused did not differ between survivors and nonsurvivors (mean +/- SD, 31 +/- 11 vs 32 +/- 10; P = .52). Stepwise multiple regression analysis identified 3 independent variables associated with mortality: need for aortic clamping, intraoperative use of inotropes, and intraoperative time with a systolic blood pressure of 90 mm Hg or less. However, blood usage was not different among the subgroups of patients who had 1 or more of these risk factors. When patients were stratified according to the amount of massive blood transfusion (20-29, 30-39, 40-49, and 50-68 U), the incidence of risk factors was not different across the 4 subgroups. Survival in the presence of risk factors was not affected by the amount of blood transfused.

CONCLUSIONS

Although mortality among critically injured patients requiring operation and massive blood transfusion can be correlated with independent risk factors, discontinuation of short-term care cannot be justified based on the need for massive blood transfusion of up to 68 units.

Lethal abdominal gunshot wounds at a level I trauma center: analysis of TRISS (Revised Trauma Score and Injury Severity Score) fallouts

BACKGROUND

The TRISS methodology (composite index of the Revised Trauma Score and the Injury Severity Score) has become widely used by trauma centers to assess quality of care. The American College of Surgeons recommends including negative TRISS fallouts (fatally injured patients predicted to survive by the TRISS methodology) as a filter to select patients for peer review. The purpose of this study was to analyze the TRISS fallouts among patients with lethal abdominal gunshot wounds admitted to a level I trauma center.

STUDY DESIGN

All patients categorized as TRISS fallouts admitted from January 1995 through December 1996 were analyzed.

RESULTS

During the study period, 848 patients with abdominal gunshot wounds were admitted. Of the 108 patients with any sign of life on admission who subsequently died, 39 (36%) were TRISS fallouts. The patients were largely young (mean age, 29 years) and male (87%), received rapid transport (mean scene time, 11 minutes), and had an attending-led trauma-team response (<5 minutes, 87%). Major vascular (80%) and multiple intraabdominal injuries (90%) predominated. The mean Penetrating Abdominal Trauma Index was 40.3. The mean TRISS probability of survival was 89%. The peer-review process deemed the deaths to be nonpreventable in 38 patients (97%) and potentially preventable in one patient (3%).

CONCLUSIONS

"TRISS fallouts" were predominantly patients who died despite receiving rapid prehospital transport, rapid senior-level trauma-team response, and surgical intervention for a serious complex of injuries. We conclude that without regional adjustment of coefficients used to predict the probability of survival, the TRISS methodology is of limited use in patients with abdominal gunshot wounds.

A selective approach to the management of gunshot wounds to the back

BACKGROUND

Gunshot wounds to the back with retroperitoneal trajectories have been traditionally managed under the same guidelines as anterior gunshot wounds. Recent work has suggested that selective nonoperative management of anterior abdominal gunshot wounds is safe. The role of this policy in gunshot wounds to the back, where retroperitoneal organ injuries may be more difficult to detect clinically, has not been investigated.

OBJECTIVE

To examine if selective nonoperative management based on clinical assessment is a safe alternative to mandatory exploration for gunshot wounds to the back.

DESIGN

Prospective study.

SETTING

Large-volume level-1 university affiliated trauma center.

PATIENTS AND METHODS

Two hundred and three consecutive patients with gunshot wounds to the back were managed according to a protocol during a 12-month period. Patients with hemodynamic instability or peritonitis underwent urgent operation. The rest of the patients were observed with careful serial clinical examinations.

RESULTS

Eleven patients underwent an emergency room thoracotomy and were excluded. Four more patients were operated upon, despite the absence of abdominal findings, because of associated spinal cord injuries (2 patients), inability to observe due to need for repair of an associated peripheral vascular injury (1 patient), and participation in another protocol of aggressive evaluation of asymptomatic patients with suspected diaphragmatic injuries (1 patient). Of the remaining 188 patients, 58 (31%) underwent laparotomy (56 therapeutic, 2 negative) and 130 (69%) were initially observed owing to negative clinical examination. Following the development of increasing abdominal tenderness, 4 of these 130 (3%) underwent delayed explorations, which were all nontherapeutic. The sensitivity and specificity of initial clinical examination in detecting significant intraabdominal injuries were 100% and 95%, respectively.

CONCLUSIONS

Mandatory laparotomy is not necessary for gunshot wounds of the back. Clinical examination is a safe method of selecting patients for nonoperative management. An observation period of 24 hours is adequate for patients with no abdominal symptoms.

Radiographic cervical spine evaluation in the alert asymptomatic blunt trauma victim: much ado about nothing

OBJECTIVE

To evaluate the hypothesis that alert nonintoxicated trauma patients with negative clinical examinations are at no risk of cervical spine injury and do not need any radiographic investigation.

DESIGN

Prospective study.

SETTING

A university-affiliated teaching county hospital.

PATIENTS

Five hundred and forty-nine consecutive alert, oriented, and clinically nonintoxicated blunt trauma victims with no neck symptoms.

RESULTS

All patients had negative clinical neck examinations. After radiographic assessment, no cervical spine injuries were identified. Less than half the patients could be evaluated adequately with the three standard initial views (anteroposterior, lateral, and odontoid). All the rest needed more radiographs and/or computed tomographic scans. A total of 2,27 cervical spine radiographs, 78 computed tomographic scans and magnetic resonance imagings were performed. Seventeen patients stayed one day in the hospital for no other reason but radiographic clearance of an asymptomatic neck. The total cost for x-rays and extra hospital days was $242,000. These patients stayed in the collar for an average of 3.3 hours (range, 0.5-72 hours). There was never an injury missed.

CONCLUSIONS

Clinical examination alone can reliably assess all blunt trauma patients who are alert, nonintoxicated, and report no neck symptoms. In the absence of any palpation or motion neck tenderness during examination, the patient may be released from cervical spine precautions without any radiographic investigations.