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Dive into the research topics where Margaret M. Knudson is active.

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Featured researches published by Margaret M. Knudson.


Journal of Trauma-injury Infection and Critical Care | 1997

Multicenter, randomized, prospective trial of early tracheostomy

Harvey J. Sugerman; Luke G. Wolfe; Michael D. Pasquale; Frederick B. Rogers; Keith F. O'Malley; Margaret M. Knudson; Laurence J. DiNardo; Michael Gordon; Scott Schaffer

OBJECTIVES Determine the effect of early (days 3-5) or late (days 10-14) tracheostomy on intensive care unit length of stay (ICU LOS), frequency of pneumonia, and mortality, and evidence of short-term or long-term pharyngeal, laryngeal, or tracheal injury in head trauma, non-head trauma, and critically ill nontrauma patients. STUDY DESIGN Randomized, prospective. SETTING Five Level I trauma centers. METHODS Data were obtained prospectively and included Acute Physiology and Chronic Health Evaluation III score (AIII), Glasgow Coma Scale score, Emergency Room Trauma Score, Injury Severity Score, Acute Injury Score, type of endotracheal tube or tracheostomy, level of positive end-expiratory pressure, and peak inspiratory pressure. Patients were to undergo laryngoscopy for detection of injury according to the Lindholm criteria at the time of endotracheal tube or tracheostomy removal and be reevaluated at 3 to 5 months after discharge. RESULTS One hundred fifty-seven patients were entered, 127 to early randomization (3-5 days) and 28 to late randomization (10-14 days); however, only 112 patients with early and 14 with late randomization had completed data forms for the primary study goals. An additional 22 patients from the early entry groups were rerandomized late. Early randomization data: the AIII score was higher (p < 0.05) in the head trauma tracheostomy (65 +/- 4) than in the nontracheostomy group (51 +/- 4) and in the nontrauma tracheostomy (92 +/- 6) than in the nontracheostomy group (68 +/- 7), but was equivalent in the non-head trauma group. Glasgow Coma Scale score, Emergency Room Trauma Score, Injury Severity Score, Acute Injury Score, positive end-expiratory pressure, and peak inspiratory pressure were not significantly different in any of the groups. There were no significant differences in ICU LOS, frequency of pneumonia, or death in any of the groups after either early or late tracheostomy compared with continued endotracheal intubation. Only 83 patients underwent postextubation laryngoscopy. There were no significant differences between the groups; however, there were trends to more vocal cord ulceration and subglottic inflammation in the continued intubation group. No patient was seen in this study with late vocal cord or laryngeal stenosis; there were no tracheal-innominate artery fistulae. Seven of the patients with abnormal findings at extubation had normal 3- to 5-month postextubation laryngoscopy. CONCLUSION Physician bias limited patient entry into the study. Although there were higher AIII scores in the head trauma early tracheostomy patients, there were no differences in the primary end points of ICU LOS, pneumonia, or death in any of the groups studied. Long-term endoscopic follow-up was poor, but no known late tracheal stenosis was seen.


Journal of Trauma-injury Infection and Critical Care | 1994

Death in the operating room: An analysis of a multi-center experience

David B. Hoyt; Bulger Em; Margaret M. Knudson; James L. Morris; Ierardi R; Sugerman Hj; Shackford; Landercasper J; Robert J. Winchell; Jurkovich G

To characterize causes of death in the operating room (OR) following major trauma, a retrospective review of admissions to eight academic trauma centers was conducted to define the etiology of death and challenges for improvement in outcome. Five hundred thirty seven OR deaths of 72,151 admissions were reviewed for mechanism of injury, physiologic findings, resuscitation, patterns of injury, surgical procedures, cause of death, and preventability. Blunt injuries accounted for 61% of all injuries, gunshot wounds (GSW) accounted for 74% of penetrating injuries. Sixty two percent of all patients arrived in shock. Average blood pressure (BP) was 52 mm Hg at the scene and 60 mm Hg on admission, with the period of shock > 10 minutes in 74%. Only 56% were resuscitated to a BP > 90 mm Hg before surgery. Average time to the OR was 30.1 minutes and mean best postresuscitation pH was 7.18. Mean best OR temperature was 32.2 degrees C. Recurrent injury patterns judged as the primary cause of patient death included head/neck injury (16.4%), chest injury (27.4%), and abdominal injury (53.4%). Actual cause of death was bleeding (82%), cerebral herniation (14.5%), and air emboli (2.2%). A different strategy for improved outcome was identified in 54 patients with the following conclusions: (1) delayed transfer to the OR remains a problem with significant BP deterioration during delay, particularly following interfacility transfer; (2) staged injury isolation and repair to allow better resuscitation and warming may lead to improved results; (3) combined thoraco-abdominal injuries, particularly with thoracic aortic disruption, often require a different sequence of management; (4) aggressive evaluation of retroperitoneal hematomas is essential; (5) OR management of severe liver injuries remains a technical challenge with better endpoints for packing needed; and (6) resuscitative thoracotomy applied to OR patients in extremis from exsanguination offers little.


Journal of Trauma-injury Infection and Critical Care | 2004

The effect of age on functional outcome in mild traumatic brain injury: 6-month report of a prospective multicenter trial

Anne C. Mosenthal; David H. Livingston; Robert F. Lavery; Margaret M. Knudson; Seong K. Lee; Diane Morabito; Geoffrey T. Manley; Avery B. Nathens; Gregory J. Jurkovich; David B. Hoyt; Raul Coimbra

OBJECTIVE Elderly patients (aged 60 years and older) have been demonstrated to have an increased mortality after isolated traumatic brain injury (TBI); however, the prognosis of those patients surviving their hospitalization is unknown. We hypothesized that surviving elderly patients would also have decreased functional outcome, and this study examined the functional outcome of patients with isolated TBI at discharge and at 6 months posthospitalization. METHODS This was a multicenter prospective study of all patients with isolated moderate to severe TBI defined as Head Abbreviated Injury Scale score of 3 with an Abbreviated Injury Scale score in any other body area of 1. Patients surviving to discharge gave their consent and were enrolled. Data collected included demographics, Glasgow Coma Scale (GCS) score at admission, and neurosurgical interventions. Outcome data included discharge disposition and Glasgow Outcome Scale score and modified Functional Independence Measure (FIM) score at discharge and at 6 months. RESULTS Two hundred thirty-five patients were enrolled, with 44 (19%) aged greater than or equal to 65 years. Mechanisms of injury were falls (34%), assaults (28%), motor vehicle collisions (14%), pedestrian (11%), and other (12%). Falls were more common in the older patients and assaults in the younger group. The mean admitting GCS score was 12.8 (95% confidence interval [CI], 12.4-13.3), with older patients having a higher mean GCS score, 14.1 (95% CI, 13.6-14.6) versus 12.5 (95% CI, 12.0-13.1; p = 0.03). There were no differences in the percentage of patients admitted to the intensive care unit or requiring neurosurgical intervention between younger and older patients. Because there were few elderly patients with low GCS scores who survived to discharge, outcome measures focused on those patients with GCS scores of 13 to 15. A greater percentage of elderly were discharged to rehabilitation (28% vs. 16%, p =0.08). The mean discharge FIM score was 10.4 (95% CI, 9.8-11.0) for the elderly versus 11.4 (95% CI, 11.1-11.7) for the young (p =0.001), with 68% elderly and 89% young discharged with total independent scores of 11 to 12. At 6 months, the difference narrowed, but the mean FIM score was still greater for the young group, 11.7 (95% CI, 11.6-11.9) versus 11.0 (95% CI, 10.6-11.4; p < 0.001). CONCLUSION Functional outcome after isolated mild TBI as measured by the Glasgow Outcome Scale and modified FIM is generally good to excellent for both elderly and younger patients. Older patients required more inpatient rehabilitation and lagged behind their younger counterparts but continued to recover and improve after discharge. Although there were statistically significant differences in the FIM score at both discharge and 6 months, the clinical importance of these small differences in the mean FIM score to the patients quality of life is less clear. Measurable improvement in functional status during the first 6 months after injury is observed in both groups. Aggressive management and care of older patients with TBI is warranted, and efforts should be made to decrease inpatient mortality. Continued follow-up is ongoing to determine whether these outcomes persist at 12 months.


Annals of Surgery | 1996

Infant survival after cesarean section for trauma

John A. Morris; T.J. Rosenbower; Gregory J. Jurkovich; David B. Hoyt; J.D. Harviel; Margaret M. Knudson; Richard S. Miller; Jon M. Burch; J. W. Meredith; Steven E. Ross; Judith M. Jenkins; John G. Bass

HYPOTHESIS Emergency cesarean sections in trauma patients are not justified and should be abandoned. SETTING AND DESIGN A multi-institutional, retrospective cohort study was conducted of level 1 trauma centers. METHODS Trauma admissions from nine level 1 trauma centers from January 1986 through December 1994 were reviewed. Pregnant women who underwent emergency cesarean sections were identified. Demographic and clinical data were obtained on all patients undergoing a cesarean section. Fetal distress was defined by bradycardia, deceleration, or lack of fetal heart tones (FHTs). Maternal distress was defined by shock (systolic blood pressure < 90) or acute decompensation. Statistical analyses were performed. RESULTS Of the 114,952 consecutive trauma admissions, more than 441 pregnant women required 32 emergency cesarean sections. All were performed for fetal distress, maternal distress, or both. Overall, 15 (45%) of the fetuses and 23 (72%) of the mothers survived. Of 33 fetuses delivered, 13 had no FHTs and none survived. Twenty infants (potential survivors) had FHTs and an estimated gestational age (EGA) of greater than or equal to 26 weeks, and 75% survived. Infant survival was independent of maternal distress or maternal Injury Severity Score. The five infant deaths in the group of potential survivors resulted from delayed recognition of fetal distress, and 60% of these deaths were in mothers with mild to moderate injuries (Injury Severity Score < 16). CONCLUSIONS In pregnant trauma patients, infant viability is defined by the presence of FHTs, estimated gestational age greater than or equal to 26 weeks. In viable infants, survival after emergency cesarean section is acceptable (75%). Infant survival is independent of maternal distress or Injury Severity Score. Sixty percent of infant deaths resulted from delay in recognition of fetal distress and cesarean section. These were potentially preventable. Given the definition of fetal viability, our initial hypothesis is invalid.


Journal of Trauma-injury Infection and Critical Care | 2000

Significance of minimal or no intraperitoneal fluid visible on CT scan associated with blunt liver and splenic injuries: A multicenter analysis

M. Gage Ochsner; Margaret M. Knudson; H. Leon Pachter; David B. Hoyt; Thomas H. Cogbill; Clyde E. McAuley; Frank E. Davis; Stan Rogers; Amber A. Guth; Joan Garcia; Pam Lambert; Norman Thomson; Scott Evans; Emil J. Balthazar; Giovanna Casola; Mark A. Nigogosyan; Richard Barr

BACKGROUND The use of ultrasound (U/S) for the evaluation of patients with blunt abdominal trauma is gaining increasing acceptance. Patients who would have undergone computed tomographic (CT) scan may now be evaluated solely with U/S. Solid organ injuries with minimal or no free fluid may be missed by surgeon sonographers. OBJECTIVE The purpose of this study was to describe the incidence and clinical importance of liver and splenic injuries with minimal or no free intraperitoneal fluid visible on CT scan. We hypothesized that these solid organ injuries occur infrequently and are of minor clinical significance. METHODS Patient records and CT scans were reviewed for the presence of and outcome associated with blunt liver and splenic injuries with minimal (<250 mL) or no free fluid detected by an attending radiologist. Data were collected from six major trauma centers during a 4-year period before the introduction of U/S and included demographics, grade of injury (American Association for the Surgery of Trauma scale), need for operative intervention, and outcome. RESULTS A total of 938 patients with liver and splenic injuries were identified. In this group, 11% of liver injuries and 12% of splenic injuries had no free fluid visible on CT scan and could be missed by diagnostic peritoneal lavage or U/S. Of the 938 patients, 267 (28%) met the inclusion criteria; 161 had injury to the spleen and 125 had injury to the liver. In the 267 patients studied, 97% of the injuries were managed nonoperatively. However, 8 patients (3%) required operative intervention for bleeding. Compared with the liver, the spleen was significantly more likely to bleed (p = 0.01), but the grade of splenic injury was not related to the risk for hemorrhage (p = 0.051). CONCLUSION Data from this study suggest that injuries to the liver or spleen with minimal or no intraperitoneal fluid visible on CT scan occur more frequently than predicted but usually are of minimal clinical significance. However, patients with splenic injuries may be missed by abdominal U/S. We found a 5% associated risk of bleeding. Therefore, abdominal U/S should not be used as the sole diagnostic modality in all stable patients at risk for blunt abdominal injury.


Journal of Trauma-injury Infection and Critical Care | 1995

Extraluminal, transluminal, and observational treatment for vertebral artery injuries

L. F. Yee; Eric W. Olcott; Margaret M. Knudson; Robert C. Lim; D. H. Wisner; J. A. Weigelt; J. A. Asensio; Steven N. Parks

Injury to the vertebral artery following penetrating trauma is rare and treatment is usually surgical ligation. Recent liberal use of angiography in the evaluation of penetrating neck trauma has identified increasing numbers of patients with this challenging injury. This report describes our recent experience in treating patients with vertebral artery injuries. The purposes of this study were (1) to review the outcome of our patients with vertebral artery injuries, and (2) to develop an approach for managing these patients. Sixteen patients were treated over a 9-year period. Three patients underwent emergent operative exploration for bleeding, three underwent transcatheter embolization alone, and ten were managed conservatively by close clinical observation. No deaths occurred. Ligation was performed for injuries discovered during neck exploration, however, bleeding was sometimes persistent despite proximal control. In our center, where radiological support is readily available, temporary control of bleeding by packing with hemostatic agents allowed subsequent transcatheter embolization of the injured artery. Pseudoaneurysms, arteriovenous fistulae, and extravasations discovered angiographically were usually managed by transcatheter embolization. Patients with vertebral artery narrowings or occlusions were managed by close clinical observation.


Journal of Trauma-injury Infection and Critical Care | 2012

Future of acute care surgery: a perspective from the next generation.

Hunter B. Moore; Peter K. Moore; Abigail R. Grant; Tiffany L. Tello; Margaret M. Knudson; Lucy Z. Kornblith; Tara E. Song; Angela Sauaia; Brian Zuckerbahn; Ernest E. Moore

Background: Access to emergent surgical care has been identified as a crisis in the United States. To address this challenge, the American Association for Surgery of Trauma has developed a fellowship in acute care surgery (ACS) to reestablish broad-based surgical capabilities. But the viability of this new discipline will rest on the interests of the next generation of surgeons. The objective of this study was to determine key factors influencing the choice of surgical specialties among medical students with a focus on their interest in trauma/ACS (T/ACS). Methods: An online questionnaire was distributed to students at four medical schools affiliated with Level I trauma centers, one of which also has an ACS fellowship. The survey was sent to medical students at all levels (first to fourth year). Students with an interest in surgery as a career were asked to complete the survey and rank factors and experiences influencing career selection on a scale of 1 (no influence) to 10 (critical). Students were also asked to select their top five surgical specialties. Results: Three hundred thirty-seven students interested in surgery responded. Mean age was 26 years ± 0.2 years (range, 20–37 years), 58% were men, and 86% were single. Respondents were distributed evenly over medical schools and medical school years. The three most popular career choices were orthopedics (16%), T/ACS (12%), and pediatric surgery (8%). As students progressed through medical school, lifestyle factors such as predictable hours and family time became more important in influencing their career choice. Overall, 115 students (34%) selected emergent surgery (T/ACS) as one of their top three career choices. Factors that were ranked significantly higher by students interested in T/ACS were related to professional satisfaction. These students also placed less emphasis on lifestyle factors when choosing a surgical career. Conclusions: Our results indicate that there is a reassuring interest to address the growing demand for emergency surgery among current medical students exposed to a broad range of T/ACS patients in Level I trauma centers. The T/ACS model is in accordance with the drives of these students looking for a diverse and challenging profession. Academic societies should make further efforts to encourage medical students to pursue T/ACS.


Journal of Trauma-injury Infection and Critical Care | 2014

Randomized controlled trial to evaluate the effectiveness of a video game as a child pedestrian educational tool

Helen Arbogast; Rita V. Burke; Valerie M. Muller; Pearl Ruiz; Margaret M. Knudson; Jeffrey S. Upperman

BACKGROUND Injury is the number one cause of death and disability in children in the United States and an increasingly important public health problem globally. While prevention of injuries is an important goal, prevention efforts are currently fragmented, poorly funded, and rarely studied. Among school-aged children, pedestrian crashes are a major mechanism of injury. We hypothesized that we could develop a game-based educational tool that would be effective in teaching elementary school children the principles of pedestrian safety. METHODS Between November 2011 and June 2013, second- and third-grade children in Los Angeles Unified School District were randomly assigned to play a unique interactive video game (Ace’s Adventure) about pedestrian safety or to a traditional didactic session about pedestrian safety. A pretest and posttest were administered to the study participants. Afterward, study participants were observed for appropriate pedestrian behavior on a simulated street set called Street Smarts. All statistical analyses were performed using SAS version 9.2. RESULTS A total of 348 study participants took the pretest and posttest. There were 180 who were randomized to the didactic and 168 who were randomized to the video game. The didactic group demonstrated a higher mean score increase (1.01, p < 0.0001) as compared with the video game group (0.44, p < 0.0001). However, observation of study participants revealed that participants who played the video game, as compared with the didactic group, more frequently exhibited appropriate behavior during the following: exiting a parked car (p = 0.01), signaling to a car that was backing up (p = 0.01), signaling to a stopped car (p = 0.0002), and crossing the street (p = 0.01). CONCLUSION Students who played the educational video game about pedestrian safety performed similarly to those who attended a more traditional and labor-intensive didactic learning. Innovative educational methods, such as game playing, could significantly change our approach to injury prevention and have the potential to decrease the burden of injury among children worldwide.


Journal of Trauma-injury Infection and Critical Care | 2017

Routine computed tomography after recent operative exploration for penetrating trauma: what injuries do we miss?

April Mendoza; Christopher A. Wybourn; Anthony G. Charles; Andre R. Campbell; Bruce A. Cairns; Margaret M. Knudson

BACKGROUND Patients with penetrating trauma who cannot be stabilized undergo operative intervention without preoperative imaging. In such cases, postoperative imaging may reveal additional injuries not identified during the initial operative exploration. The purpose of this study is to explore the utility of postoperative CT imaging in the setting of penetrating trauma. METHODS This was a retrospective analysis of patients with penetrating trauma treated at an urban Level 1 trauma center between 2010 and 2015. Patients were included if they underwent an emergent laparotomy without preoperative imaging. Patients were excluded if they had prior imaging or concomitant blunt injury. For the purposes of this study, occult injury was defined as a CT scan finding not mentioned in the first operative report. Descriptive statistics were used to compare patient characteristics who had received imaging immediately postoperatively with those who had not. RESULTS During the 5-year study period, 328 patients who had a laparotomy for penetrating trauma over the study period, 225 patients met the inclusion criteria. Seventy-three (32%) patients underwent CT scanning immediately postoperatively with occult injuries identified in 38 (52%) patients. The most frequent occult injuries were orthopedic (20 of 43) and genitourinary (9 of 43). Importantly, 10 (26%) of the 38 patients required an intervention for these occult injuries. Those selected for immediate postoperative imaging were more likely to have sustained gunshot wounds and were significantly more severely injured (higher Injury Severity Score and longer length of hospital stay) when compared to patients who did not receive immediate imaging. CONCLUSION We recommend the use of immediate postoperative CT after emergent laparotomy especially when there is a high index of suspicion for spine or genitourinary injuries and in patients who have sustained ballistic penetrating injuries. LEVEL OF EVIDENCE Therapeutic/care management, level IV; diagnostic tests or criteria, level IV.


Trauma | 2017

High-risk mechanism of injury: A new indication for screening for blunt cerebrovascular injury?

April Mendoza; Christopher A. Wybourn; Margaret M. Knudson

Blunt cerebrovascular injury is a rare but catastrophic injury. Screening for blunt cerebrovascular injury after high-impact mechanism remains ill-defined but several associated lesions have been identified as high risk for concomitant blunt cerebrovascular injury and are used to prompt further investigation for early identification and intervention. We describe a case of a large cerebral infarction caused by a high cervical internal carotid dissection after a motorcycle collision. Upon presentation, the patient had a Glasgow coma scale of 14 and an open pelvic fracture, which was immediately addressed in the operating room. His subsequent imaging revealed a nasal fracture, bilateral rib fractures, bilateral pubic rami fractures and left acetabular fracture without evidence of traumatic brain injury, cervical spine injury or extensive facial fractures. After 48 h, he displayed a depressed sensorium and an abnormal pupillary exam. He was diagnosed by computed tomography angiogram with a carotid dissection resulting in a large infarct of the right hemisphere with herniation requiring emergent craniectomy. This case suggests screening for blunt cerebrovascular injury beyond the current recommendations especially in patients with high-impact mechanism.

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Diane Morabito

University of California

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David B. Hoyt

American College of Surgeons

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Nikita Derugin

University of California

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Raul Coimbra

University of California

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Robert F. Lavery

University of Medicine and Dentistry of New Jersey

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Seong K. Lee

University of California

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