Preston R. Miller

Prospective screening for blunt cerebrovascular injuries: analysis of diagnostic modalities and outcomes.

ObjectiveTo prospectively examine outcomes associated with an aggressive screening protocol for blunt cerebrovascular injury (BCVI), and to compare the accuracy of computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) versus conventional angiography with respect to BCVI diagnosis. Summary Background DataIn the past 5 years, BCVI (carotid and vertebral arteries) has been recognized with increasing frequency. Initial studies described blunt carotid injuries and their associated morbidity, while more recent reports have established the devastating potential of blunt vertebral injuries. It has been suggested that early diagnosis and anticoagulation will improve outcomes and that less-invasive diagnostic techniques than conventional angiography are desirable for screening. However, there are neither established screening criteria nor studies comparing optimal diagnostic modalities. MethodsThe screened population included all patients with cervical spine fractures, LeFort II or III facial fractures, Horner’s syndrome, skull base fractures involving the foramen lacerum, neck soft tissue injury, or neurological abnormalities unexplained by intracranial injuries. Patients underwent screening with four-vessel cerebral angiography. During the first half of the study, patients also underwent helical CTA. Selected patients during this same period underwent MRA. At the time of diagnosis, anticoagulant or antiplatelet therapy was instituted unless clinically contraindicated. Results of this screening protocol were compared to a previously published cohort with cerebrovascular injuries (1995–1999) from the authors’ institution. ResultsTwo hundred sixteen patients were screened over a 2-year period (3.5% of all blunt trauma admissions). Angiography identified 24 patients with carotid artery injuries (CAI) and 43 patients with vertebral artery injuries (VAI) for an overall screening yield of 29%. While the incidence of CAI remained similar between the current study and the previous study group, the incidence of VAI diagnosis increased. Stroke rates in those with CAI were also similar between the two periods. The stroke rate in VAI, however, was markedly lower at 0% as compared to 14% in the previous group. Comparison of CTA and MRA with cerebral angiography in 143 patients demonstrated sensitivities of 47% and 50%, respectively, for CAI; sensitivities were 53% (CTA) and 47% (MRA) for VAI. ConclusionsAggressive screening of patients with blunt head and neck trauma identified an incidence of BCVI in 1.03% of blunt admissions. Early identification, which led to early treatment, significantly reduced stroke rates in patients with VAI, but provided no outcome improvement with CAI. More encompassing screening may be required to improve outcomes for patients with CAI. However, less-invasive diagnostic techniques (CTA and MRA) are inadequate for screening. Technological advances are necessary before abandonment of conventional angiography, which remains the standard for diagnosis.

Prospective evaluation of vacuum-assisted fascial closure after open abdomen: planned ventral hernia rate is substantially reduced.

Objective:The goal of this report is to examine the success of vacuum-assisted fascial closure (VAFC) under a carefully applied protocol in abdominal closure after open abdomen. Summary Background Data:With the development of damage control techniques and the understanding of abdominal compartment syndrome, the open abdomen has become commonplace in trauma patients. If the abdomen is not closed in the early postoperative period, the combination of adhesions and fascial retraction frequently make primary fascial closure impossible and creation of a planned ventral hernia is required. We have previously reported our experience with the development of a technique for VAFC that allowed for closure of the fascia in many such patients long after initial operation. During this previous study, during which the technique was being developed, VAFC was successful in 69% of patients in whom it was applied, and 22 patients were successfully closed at ≥ 9 days after initial surgery (range, 9 to 49 days). A protocol for the use of VAFC in patients with open abdomen was developed on the basis of these data and has been employed since October 2001. The outcome of this protocols use is examined. Methods:This is a prospective evaluation of all trauma patients admitted to Wake Forest University Baptist Medical Center over a 19-month period who required management with an open abdomen. VAFC employs suction applied to a large polyurethane sponge under an occlusive dressing in the wound and allows for constant medial traction of the abdominal fascia. It is attempted in all patients in whom the rectus muscles and fascia are intact. Studied variables include fascial closure rate, time to closure, incidence of wound dehiscence, and hernia development after closure. Results:From November 1, 2001, through May 31, 2003, 212 laparotomies were performed in injured patients; 53 (25%) of these patients required open abdomen management. Mean injury severity score for the group was 34, with an average abdominal abbreviated injury score of 2.9. Forty-five (78%) survived until abdominal closure. Vacuum dressings were used in all 45 but VAFC was not attempted in 2 patients (1 due to development of enterocutaneous fistula, 1 because a rectus flap was used for another wound). Closure rate in those undergoing VAFC was 88% (38), with mean time to closure being 9.5 days. This is significantly higher than the 69% rate of fascial closure during the time in which the technique was developed (P = 0.03). Twenty-one patients (48%) were closed at ≥ 9 days (range, 9 to 21 days). Two patients (4.6%) developed wound dehiscence and underwent successful reclosure. One patient (2.3%) developed a ventral hernia on follow-up, which has since been repaired Conclusions:The use of VAFC under a carefully defined protocol has resulted in significantly higher fascial closure rates, obviating the need for subsequent hernia repair in most patients. The utility of this technique is not limited to the early postoperative period, but it can be successful as much as 3 to 4 weeks after initial operation.

Blunt cerebrovascular injuries: diagnosis and treatment.

BACKGROUND Blunt cerebrovascular injuries (BCVIs), once thought to be rare, have been recognized with increasing frequency in recent years. An incidence of 0.33% for carotid artery injury (CAI) was noted from our institution, with 24% stroke-related mortality. Vertebral artery injury (VAI) has been thought both rare and of questionable significance. Incidence, associated injury patterns, and outcomes were examined during a period of aggressive screening (four-vessel angiography). METHODS Patients with BCVI were identified from the registry of a Level I trauma center over a 5-year period (1995-1999). RESULTS One hundred thirty-nine BCVIs were identified in 96 patients: 75 were CAIs (14 bilateral), 64 were VAIs (14 bilateral), and 15 patients had both CAI and VAI. The incidence of CAI was 0.5% of all blunt trauma admissions, significantly higher than our earlier experience (p < 0.0002), whereas that for VAI was 0.4%. Thirty-four percent of CAIs were diagnosed because of ischemic changes and 38% because of injury pattern (neck, Horner syndrome, basilar skull fracture); only 12% of VAIs were diagnosed because of posterior circulation ischemia, with 64% because of injury pattern (cervical spine, soft tissue, facial fracture). Stroke-related mortality for CAI was 13%, and that for VAI was 4%. Forty-three of the 75 CAIs were treated (anticoagulation/antiplatelet) before development of ischemia. Thirty-nine of the 50 VAI patients were treated before development of ischemia. Stroke rate for CAI was 31% (hemiplegia/hemiparesis) and for VAI was 14% (brain stem dysfunction). Stroke rate for treated vessels (heparin, antiplatelet therapy) with CAI was 6.8% compared with 64% in untreated vessels (p < 0.001). Treated patients with VAI had a stroke rate of 2.6%, whereas untreated patients developed stroke 54% of the time. CONCLUSION Increased awareness and aggressive screening have resulted in significantly increased incidence of diagnosis of CAI, with associated lower stroke-related mortality. VAIs have been noted with similar incidence, and though the stroke rate is lower with VAI, stroke outcomes are generally catastrophic. Anticoagulation therapy is effective for both varieties of BCVI.

External fixation or arteriogram in bleeding pelvic fracture: initial therapy guided by markers of arterial hemorrhage.

BACKGROUND Bleeding pelvic fractures (BPF) carry mortality as high as 60%, yet controversy remains over optimal initial management. Some base initial intervention on fracture pattern, with immediate external fixation (EX FIX) in amenable fractures aimed at controlling venous bleeding. Others feel ongoing hemodynamic instability indicates arterial bleeding, and prefer early angiography (ANGIO) before EX-FIX. Our aim was to evaluate markers of arterial bleeding in patients with BPF, thus identifying patients requiring early ANGIO regardless of fracture pattern. METHODS Patients with pelvis fracture were identified from a Level I trauma center registry over a 7-year period and records reviewed. From this group, two subsets were analyzed: those with initial hypotension related to pelvic fracture, and those without hypotension who underwent pelvic ANGIO. Data included hemodynamics, response to resuscitation, presence of contrast blush on CT, fracture treatment and outcome. Adequate response to initial resuscitation (R) was defined as a sustained (>2 hours) improvement of systolic blood pressure to >90 mm Hg systolic after the administration of < or = 2 units packed red blood cells. Those with repeated episodes of hypotension despite resuscitation were classified as non-responders (NR) RESULTS: From 1/94-1/01, 1171 patients were admitted with pelvic ring fracture. Thirty-five (0.3%) had hypotension attributable to pelvis fracture. 28 fell into the NR group, and 26 of these underwent ANGIO. Nineteen (73%) showed arterial bleeding while 3 resuscitation response patients underwent ANGIO with none demonstrating bleeding (p = 0.03). Sensitivity and specificity of inadequate response to initial resuscitation for predicting the presence of arterial bleeding on ANGIO were 100% and 30% respectively while negative and positive predictive value were 100% and 73%. In patients with fractures amenable to external fixation (n = 16), 44% had arterial bleeding on ANGIO, and all were in the NR group. An additional 17 patients without hypotension also underwent ANGIO. Contrast blush on admission CT was seen in 4, 3 of which had arterial bleeding seen on ANGIO (75%). Sensitivity and specificity for contrast blush in predicting bleeding on ANGIO were 60% and 92% with positive and negative predictive value being 75% and 85%. CONCLUSIONS In patients with hypotension and pelvic fracture, therapy selection based on initial response to resuscitation in BPF yields a 73% positive ANGIO rate in NR patients. Delay in ANGIO for EX FIX in patients with amenable fractures would have delayed embolization in the face of ongoing arterial bleeding in 44% of patients. In stable patients with pelvic fracture, contrast blush also indicates a high likelihood of arterial injury and ANGIO is indicated. Optimal therapy in the face of BPF requires early determination of the presence of arterial bleeding so that ANGIO can be rapidly obtained, and response to initial resuscitation as well as the presence of contrast blush aid in this decision.

ARDS after pulmonary contusion: accurate measurement of contusion volume identifies high-risk patients.

BACKGROUND The pathophysiology of pulmonary contusion (PC) is poorly understood, and only minimal advances have been made in management of this entity over the past 20 years. Improvement in understanding of PC has been hindered by the fact that there has been no accurate way to quantitate the amount of pulmonary injury. With this project, we examine a method of accurately measuring degree of PC by quantifying contusion volume relative to pulmonary function and outcome. METHODS Patients with PC from isolated chest trauma who had admission chest computed tomographic scan were identified from the registry of a Level I trauma center over a 1.5-year period. Subsequently, prospective data on all patients admitted to the intensive care unit with PC during a 5-month period were collected and added to the retrospective database. Using computer-generated three-dimensional reconstruction from admission chest computed tomographic scan, contusion volume was measured and expressed as a percentage of total lung volume. Admission pulmonary function variables (Pao2/FiO2, static compliance), injury descriptors (chest Abbreviated Injury Score, Injury Severity Score, injury distribution), and indicators of degree of shock (admission systolic blood pressure, admission base deficit) were documented. Outcomes included maximum positive end-expiratory pressure, ventilator days, pneumonia, and acute respiratory distress syndrome (ARDS). RESULTS Forty-nine patients with PC (35 bilateral) were identified. The average severity of contusion was 18% (range, 5-55%). Patients were classified using contusion volume as severe PC (> or =20%, n = 17) and moderate PC (< 20%, n = 32). Injury Severity Score was similar in the severe and moderate groups (23.3 vs. 26.5, p = 0.33), as were admission Glasgow Coma Scale score (12 vs. 13, p = 0.30), admission blood pressure (131 vs. 129 mm Hg, p = 0.90), and admission Pao2/Fio2 (197 vs. 255, p = 0.14). However, there was a much higher rate of ARDS in the severe group as compared with the moderate group (82% vs. 22%, p < 0.001). There was a trend toward higher pneumonia rate in the severe group, with 50% of patients in the severe group developing pneumonia as compared with 28% in the moderate group (p = 0.20). CONCLUSION Extent of contusion volumes measured using three-dimensional reconstruction allows identification of patients at high risk of pulmonary dysfunction as characterized by development of ARDS. This method of measurement may provide a useful tool for the further study of PC as well as for the identification of patients at high risk of complications at whom future advances in therapy may be directed.

Trial of Short-Course Antimicrobial Therapy for Intraabdominal Infection

BACKGROUND The successful treatment of intraabdominal infection requires a combination of anatomical source control and antibiotics. The appropriate duration of antimicrobial therapy remains unclear. METHODS We randomly assigned 518 patients with complicated intraabdominal infection and adequate source control to receive antibiotics until 2 days after the resolution of fever, leukocytosis, and ileus, with a maximum of 10 days of therapy (control group), or to receive a fixed course of antibiotics (experimental group) for 4±1 calendar days. The primary outcome was a composite of surgical-site infection, recurrent intraabdominal infection, or death within 30 days after the index source-control procedure, according to treatment group. Secondary outcomes included the duration of therapy and rates of subsequent infections. RESULTS Surgical-site infection, recurrent intraabdominal infection, or death occurred in 56 of 257 patients in the experimental group (21.8%), as compared with 58 of 260 patients in the control group (22.3%) (absolute difference, -0.5 percentage point; 95% confidence interval [CI], -7.0 to 8.0; P=0.92). The median duration of antibiotic therapy was 4.0 days (interquartile range, 4.0 to 5.0) in the experimental group, as compared with 8.0 days (interquartile range, 5.0 to 10.0) in the control group (absolute difference, -4.0 days; 95% CI, -4.7 to -3.3; P<0.001). No significant between-group differences were found in the individual rates of the components of the primary outcome or in other secondary outcomes. CONCLUSIONS In patients with intraabdominal infections who had undergone an adequate source-control procedure, the outcomes after fixed-duration antibiotic therapy (approximately 4 days) were similar to those after a longer course of antibiotics (approximately 8 days) that extended until after the resolution of physiological abnormalities. (Funded by the National Institutes of Health; STOP-IT ClinicalTrials.gov number, NCT00657566.).

Injury-associated hypothermia: an analysis of the 2004 National Trauma Data Bank.

Severe injury and shock are frequently associated with abnormalities in patient body temperature. Substantial increases in mortality have been associated with profound hypothermia, especially below 35°C. The purpose of this study was to further characterize the impact of hypothermia in a large dataset of trauma patients. This study was a retrospective analysis of the 2004 version of the National Trauma Data Bank (NTDB), which contains approximately 1.1 million patients from over 400 trauma centers. Admission temperature was analyzed with respect to mortality, injury severity score (ISS), base deficit (BD), Glasgow Coma Score (GCS), and hospital outcomes. The NTDB contained 701,491 patients with temperatures recorded upon trauma center admission. Of these, 11,026 patients had admission temperatures <35°C, and 802 had temperatures <32°C. Comparison of core temperature versus mortality revealed that as temperature decreased, the mortality rate increased, reaching approximately 39% at 32°C, and remained constant at lower temperatures. Surprisingly, 477 patients (59.5%) survived with temperatures <32°C. Similarly, BD increased as hypothermia worsened until body temperature reached 31°C, below which there was little further increase. Patients with admission temperatures less than 35°C had significantly greater mortality (25.5% vs. 3.0%, P < 0.001) and BD (7.8 vs. 3.7, P < 0.001) when compared with patients with temperatures ≥35°C. In survivors, average ventilator days and intensive care unit (ICU) days were 14.4 and 12.8, respectively, for patients with temperatures <35°C as opposed to more normothermic patients who demonstrated an average of 9.5 ventilator days and 9.1 ICU days (P < 0.001). When grouped by individual ISS, BD level, and GCS motor score, mortality was significantly greater when admission temperature was below 35°C (ISS mean difference = 11.4%, BD mean difference = 22.8%, and GCS motor mean difference = 9.85%). Logistic regression revealed that hypothermia remains an independent determinant of mortality after correction for confounding variables (odds ratio = 1.54, 95% confidence interval 1.40-1.71). Admission hypothermia is associated with greater mortality, increased injury severity, more profound acidosis, and prolonged ICU/ventilator courses. However, although mortality at <32°C is high, patients with temperatures this low do survive. As temperatures drop below 32°C, mortality rates remain constant, which may indicate a threshold below which physiologic mechanisms are unable to correct body temperature regardless of injury severity. Although shock severity is highly indicative of outcome, hypothermia independently contributes to the substantial mortality associated with severe injury.

Elevated arterial base deficit in trauma patients: a marker of impaired oxygen utilization

BACKGROUND In trauma patients, the admission value of arterial base deficit stratifies injury severity, predicts complications, and is correlated with arterial lactate concentration. In theory, elevated base deficit and lactate concentrations after shock are related to oxygen transport imbalance at the cellular level. The purpose of this study was to test the hypothesis that an elevated base deficit in trauma patients is indicative of impaired systemic oxygen utilization and portends poor outcomes. METHODS This study was a retrospective analysis of a prospectively collected database. The study population included all patients admitted to the trauma intensive care unit at a Level 1 trauma center during a 12-month period who were monitored with a pulmonary artery catheter and serial measurements of lactate and base deficit, and who achieved a normal arterial lactate concentration (< 2.2 mmol/L) with resuscitation. The patients were divided into those who maintained a persistently high base deficit (> or = 4 mmol/L) and those who achieved a low base deficit (< 4 mmol/L) during resuscitation. RESULTS One-hundred patients (mortality 20%) were monitored with a pulmonary artery catheter and achieved a normal arterial lactate concentration. The mean age+/-SD (SEM) of the group was 37+/-17 years and the Injury Severity Score was 25+/-11. Subgroup analysis revealed that patients with a persistently high base deficit (n=26) had higher rates of multiple organ failure (35% versus 5%, p < 0.001) and death (50% versus 9%, p < 0.00001) compared with patients who achieved a low base deficit. Patients with a persistently high base deficit also had lower oxygen consumption (126+/-40 mL/m2 versus 156+/-30 mL/m2, p=0.01 at 48 hours) and a lower oxygen utilization coefficient (0.20+/-0.05 versus 0.24+/-0.03, p=0.01 at 48 hours) compared with patients with a low base deficit. At 48 hours, both oxygen consumption (r=-0.44, [r, correlation coefficient] p=0.002) and oxygen utilization (r=-0.46, p=0.001) had a significant negative correlation with base deficit. CONCLUSIONS In trauma patients, a persistently high arterial base deficit is associated with altered oxygen utilization and an increased risk of multiple organ failure and mortality. Serial monitoring of base deficit may be useful in assessing the adequacy of oxygen transport and resuscitation.

Does Optimal Timing for Spine Fracture Fixation Exist

ObjectiveTo evaluate the effect of timing of spine fracture fixation on outcome in multiply injured patients. Summary Background DataThere is little consensus regarding the optimal timing of spine fracture fixation after blunt trauma. Potential advantages of early fixation include earlier patient mobilization and fewer septic complications; disadvantages include compounded complications from associated injuries and inconvenience of surgical scheduling. MethodsPatients with spine fractures from blunt trauma admitted to an urban level 1 trauma center during a 42-month period who required surgical spine fracture fixation were identified from the registry. Patients were analyzed according to timing of fixation, level of spine injury, and impact of associated injuries (measured by injury severity score). Early fixation was defined as within 3 days of injury, and late fixation was after 3 days. Outcomes analyzed were intensive care unit and hospital stay, ventilator days, pneumonia, survival, and hospital charges. ResultsTwo hundred ninety-one patients had spine fracture fixation, 142 (49%) early and 149 (51%) late. Patients were clinically similar relative to age, admission blood pressure, injury severity score, and chest abbreviated injury scale score. The intensive care unit stay was shorter for patients with early fixation. The incidence of pneumonia was lower for patients with early fixation. Charges were lower for patients with early fixation. Patients were stratified by level of spine injury. There were 163 cervical (83 early, 80 late), 79 thoracic (30 early, 49 late), and 49 lumbar fractures (29 early, 20 late). There were no differences in injury severity between early and late groups for each fracture site. The most striking differences occurred in the thoracic fracture group. Early fixation was associated with a lower incidence of pneumonia, a shorter intensive care unit stay, fewer ventilator days, and lower charges. High-risk patients had lower pneumonia rates and less hospital resource utilization with early fixation. ConclusionsEarly spine fracture fixation is safely performed in multiply injured patients. Early fixation is preferred in patients with thoracic spine fractures because it allows earlier mobilization and reduces the incidence of pneumonia. Although delaying fixation in the less severely injured may be convenient for scheduling, it increases hospital resource utilization and patient complications.

Effects of Abdominal Decompression on Cardiopulmonary Function and Visceral Perfusion in Patients with Intra-abdominal Hypertension

OBJECTIVE Increased intra-abdominal pressure (IAP) compromises cardiopulmonary function and visceral perfusion. Our goal was to characterize acute changes in these subsystems associated with operative abdominal decompression. PATIENT POPULATION A series of 11 consecutive injured patients monitored with a pulmonary artery catheter and nasogastric tonometer in whom operative decompression was performed. Indications for decompression included oliguria or progressive acidosis despite aggressive resuscitation in the presence of elevated IAP (>25 mm Hg). MAIN OUTCOME MEASURES Studied hemodynamic variables included pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic volume index (RVEDVI), and cardiac index (CI). Pulmonary variables included shunt fraction (Qs/Qt) and dynamic compliance (Cdyn). Visceral perfusion was assessed using hourly urine output 4 hours before and after decompression (UOP) and gastric intramucosal pH (pHi). Mean values before and after decompression were compared using the paired t test. Linear regression and Fishers z transformation were used to evaluate the relationships between RVEDVI, PAOP, CI, and IAP. IAP was transduced via bladder pressures. Significance was defined as p < 0.05. Data are expressed as means+/-SD. RESULTS IAP decreased with decompression (49+/-11 to 19+/-6.8 mm Hg; p < 0.0001). RVEDVI improved independent of CI and correlated better (p < 0.01) with CI (r =0.49, p=0.04) than PAOP did (r=-0.36, p=0.09). PAOP correlated significantly with IAP (r=0.45, p=0.04). Decompression resulted in significant improvements in Qs/Qt, Cdyn, UOP, and pHi. CONCLUSION Abdominal decompression in patients with increased IAP improves preload, pulmonary function, and visceral perfusion. Elevated IAP has important effects on PAOP, which makes the PAOP an unreliable index of preload in these patients.