Roxanne R. Roberts

The utility of head computed tomography after minimal head injury

OBJECTIVE To determine if patients who present with a history of loss of consciousness who are neurologically intact (minimal head injury) should be managed with head computed tomography (CT), observation, or both. METHODS We prospectively studied patients who presented to our urban Level I trauma center with a history of loss of consciousness after blunt trauma and a Glasgow Coma Scale score of 15. All patients underwent CT of the head and were subsequently admitted for 24 hours of observation. RESULTS A total of 1,170 patients with minimal head injury were studied during a 35-month period. All patients had Glasgow Coma Scale scores of 15 on arrival and had a history of either loss of consciousness or amnesia to the event. Two hundred forty-seven patients (21.1%) were intoxicated with drugs or alcohol on admission; 39 patients (3.3%) had abnormalities detected by CT, including 18 intracranial bleeds; 21 patients (1.8%) had changes in therapy as a direct result of their CT results, including 4 operative procedures. No patient with negative CT results deteriorated during the subsequent observation period. CONCLUSION CT is a useful test in patients with minimal head injury because it may lead to a change in therapy in a small but significant number of patients. Subsequent hospital observation adds nothing to the CT results and is not necessary in patients with isolated minimal head injury.

Transfusions result in pulmonary morbidity and death after a moderate degree of injury.

BACKGROUND Prior studies have suggested that blood transfusion (Tx) is associated with infectious and respiratory complications in trauma patients. However, these studies are difficult to interpret because of small sample size, inclusion of severely injured patients in traumatic shock, and combination of a variety of unrelated low-morbidity/mortality infections, such as wound, catheter-related, and urinary tract infection as outcomes. To eliminate these confounding variables, this study evaluates the association between delayed Tx and serious, well-defined respiratory complications (ventilator-associated pneumonia [VAP] and acute respiratory distress syndrome [ARDS]) and death in a cohort of intensive care unit (ICU) admissions with less severe (Injury Severity Score [ISS] < 25) blunt trauma who received no Tx within the initial 48 hours after admission. METHODS Patients with blunt injury and ISS < 25 admitted to the ICU over a 7-year period were identified from the registry and excluded if within 48 hours from admission they received any Tx or if they died. VAP required quantitative bronchoalveolar lavage culture (> or =10(5) colonies/mL), and ARDS required Pao2/Fio2 ratio < 200 mm Hg, *** no congestive heart failure, diffuse bilateral infiltrates, and peak airway pressure > 50 cm H2O for diagnosis. Outcomes were VAP, ARDS, and death. RESULTS Nine thousand one hundred twenty-six with blunt injury were ICU admissions, and 5,260 (58%) met study criteria (72% male). Means for age, ISS, and Glasgow Coma Scale score were 39, 12, and 14, respectively. There were 778 (15%) who received delayed Tx. Incidences of VAP, ARDS, and death were 5%, 1%, and 1%, respectively. Logistic regression analysis identified age, base excess, chest Abbreviated Injury Scale score, ISS, and any transfusion as significant predictors for VAP; chest Abbreviated Injury Scale score and transfusion as significant predictors for ARDS; and age and transfusion as significant predictors for death. CONCLUSION Delayed transfusion is independently associated with VAP, ARDS, and death in trauma patients regardless of injury severity. These data mandate a judicious transfusion policy after resuscitation and emphasize the need for safe and effective blood substitutes and transfusion alternatives.

CT should replace three-view radiographs as the initial screening test in patients at high, moderate, and low risk for blunt cervical spine injury: a prospective comparison.

BACKGROUND An estimated 10,000 Americans suffer cervical spine injuries each year. More than 800,000 cervical spine radiographs (CSR) are ordered annually. The human and healthcare costs associated with these injuries are enormous especially when diagnosis is delayed. Controversy exists in the literature concerning the diagnostic accuracy of CSR, with reported sensitivity ranging from 32% to 89%. We sought to compare prospectively the sensitivity of cervical CT (CCT) to CSR in the initial diagnosis of blunt cervical spine injury for patients meeting one or more of the NEXUS criteria. METHODS The study prospectively compared the diagnostic accuracy of CSR to CCT in consecutive patients evaluated for blunt trauma during 23 months at an urban, public teaching hospital and Level I Trauma Center. Inclusion criteria were adult patient, evaluated for blunt cervical spine injury, meeting one or more of the NEXUS criteria. All patients received both three-view CSR and CCT as part of a standard diagnostic protocol. Each CSR and CCT study was interpreted independently by a different radiology attending who was blinded to the results of the other study. Clinically significant injuries were defined as those requiring one or more of the following interventions: operative procedure, halo application, and/or rigid cervical collar. RESULTS Of 1,583 consecutive patients evaluated for blunt cervical spine trauma, 78 (4.9%) patients received only CCT or CSR and were excluded from the study. Of the remaining 1,505 patients, 78 (4.9%) had evidence of a radiographic injury by CSR or CCT. Of these 78 patients with radiographic injury, 50 (3.3%) patients had clinically significant injuries. CCT detected all patients with clinically significant injuries (100% sensitive), whereas CSR detected only 18 (36% sensitive). Of the 50 patients, 15 were at high risk, 19 at moderate risk, and 16 at low risk for cervical spine injury according to previously published risk stratification. CSR detected clinically significant injury in 7 high risk (46% sensitive), 7 moderate risk (37% sensitive), and 4 low risk patients (25% sensitive). CONCLUSION Our results demonstrate the superiority of CCT compared with CSR for the detection of clinically significant cervical spine injury. The improved ability to exclude injury rapidly provides further evidence that CCT should replace CSR for the initial evaluation of blunt cervical spine injury in patients at any risk for injury.

TASER X26 Discharges in Swine Produce Potentially Fatal Ventricular Arrhythmias

OBJECTIVES Data from the authors and others suggest that TASER X26 stun devices can acutely alter cardiac function in swine. The authors hypothesized that TASER discharges degrade cardiac performance through a mechanism not involving concurrent acidosis. METHODS Using an Institutional Animal Care and Use Committee (IACUC)-approved protocol, Yorkshire pigs (25-71 kg) were anesthetized, paralyzed with succinylcholine (SCh; 2 mg/kg), and then exposed to two 40-second discharges from a TASER X26 with a transcardiac vector. Vital signs, blood chemistry, and electrolyte levels were obtained before exposure and periodically for 48 hours postdischarge. Electrocardiograms and echocardiography (echo) were performed before, during, and after the discharges. p-Values < 0.05 were considered significant. RESULTS Electrocardiograms were unreadable during the discharges due to electrical interference, but echo images showed unmistakably that cardiac rhythm was captured immediately at a rate of 301 +/- 18 beats/min (n = 8) in all animals tested. Capture continued for the duration of the discharge and in one animal degenerated into fatal ventricular fibrillation (VF). In the remaining animals, ventricular tachycardia (VT) occurred postdischarge for 1-17 seconds, whereupon sinus rhythm was regained spontaneously. Blood chemistry values and vital signs were minimally altered postdischarge and no significant acidosis was seen. CONCLUSIONS Extreme acid-base disturbances usually seen after lengthy TASER discharges were absent with SCh, but TASER X26 discharges immediately and invariably produced myocardial capture. This usually reverted spontaneously to sinus rhythm postdischarge, but fatal VF was seen in one animal. Thus, in the absence of systemic acidosis, lengthy transcardiac TASER X26 discharges (2 x 40 seconds) captured myocardial rhythm, potentially resulting in VT or VF in swine.

Mild hypothermia increases survival from severe pressure-controlled hemorrhagic shock in rats

BACKGROUND In previous studies, mild hypothermia (34 degrees C) during uncontrolled hemorrhagic shock (HS) increased survival. Hypothermia also increased mean arterial pressure (MAP), which may have contributed to its beneficial effect. We hypothesized that hypothermia would improve survival in a pressure-controlled HS model and that prolonged hypothermia would further improve survival. METHODS Thirty rats were prepared under light nitrous oxide/halothane anesthesia with spontaneous breathing. The rats underwent HS with an initial blood withdrawal of 2 mL/100 g over 10 minutes and pressure-controlled HS at a MAP of 40 mm Hg over 90 minutes (without anticoagulation), followed by return of shed blood and additional lactated Ringers solution to achieve normotension. Hemodynamic monitoring and anesthesia were continued to 1 hour, temperature control to 12 hours, and observation without anesthesia to 72 hours. After HS of 15 minutes, 10 rats each were randomized to group 1, with normothermia (38 degrees C) throughout; group 2, with brief mild hypothermia (34 degrees C during HS 15-90 minutes plus 30 minutes after reperfusion); and group 3, with prolonged mild hypothermia (same as group 2, then 35 degrees C [possible without shivering] from 30 minutes after reperfusion to 12 hours). RESULTS MAP during HS and initial resuscitation was the same in all three groups, but was higher in the hypothermia groups 2 and 3, compared with the normothermia group 1, at 45 and 60 minutes after reperfusion. Group 1 required less blood withdrawal to maintain MAP 40 mm Hg during HS and more lactated Ringers solution for resuscitation. At end of HS, lactate levels were higher in group 1 than in groups 2 and 3 (p < 0.02). Temperatures were according to protocol. Survival to 72 hours was achieved in group 1 by 3 of 10 rats, in group 2 by 7 of 10 rats (p = 0.18 vs. group 1), and in group 3 by 9 of 10 rats (p = 0.02 vs. group 1, p = 0.58 vs. group 2). Survival time was longer in group 2 (p = 0.09) and group 3 (p = 0.007) compared with group 1. CONCLUSION Brief hypothermia had physiologic benefit and a trend toward improved survival. Prolonged mild hypothermia significantly increased survival after severe HS even with controlled MAP. Extending the duration of hypothermia beyond the acute phases of shock and resuscitation may be needed to ensure improved outcome after prolonged HS.

Evisceration after Abdominal Stab Wounds: Is Laparotomy Required?

OBJECTIVES To determine the incidence of intra-abdominal injury requiring laparotomy after an abdominal stab wound with evisceration. To identify clinical signs that increase the likelihood of an intra-abdominal injury in the presence of such a wound. METHODS Information was collected prospectively over an 8-year period on all patients who presented to our urban level I trauma center with an abdominal stab wound and evisceration. This information included which organ eviscerated, presence of other indications for laparotomy, organs injured, and postoperative complications. All comparisons used the Fishers exact chi2. RESULTS A total of 81 patients were admitted with evisceration after an abdominal stab wound. Sixty-one patients (75%) had eviscerated omentum, 18 patients (22%) had eviscerated small bowel, and 2 patients (2%) had eviscerated colon. Sixty-two patients (76%) had evisceration as the sole indication for laparotomy, the remaining 19 patients (24%) had another indication such as hypotension or peritonitis. Overall, 63 patients (78%) had an intra-abdominal injury that required repair. This was true regardless of organ eviscerated (omentum = 77% vs. viscus = 80%, not significant) or clinical presentation (no other indication = 76% vs. another indication = 84%, not significant). CONCLUSION The majority of patients who present with an evisceration after a stab wound to the abdomen require a laparotomy. This is true regardless of what has eviscerated or the presence of other clinical indications to operate. Evisceration should continue to prompt operative intervention.

Determining which patients require evaluation for blunt cardiac injury following blunt chest trauma.

Abstract. The objective of this study was to determine prospectively which risk factors require cardiac monitoring for blunt cardiac injury (BCI) following blunt chest trauma. All patients who sustained blunt chest trauma had an electrocardiogram (ECG) on admission to our urban level I trauma center. Those with ST segment changes, dysrhythmias, hemodynamic instability, history of cardiac disease, age >55 years, or a need for general anesthesia within 24 hours (group 1) were admitted to the intensive care unit (ICU) for 24 hours where they were subjected to serial ECGs, creatinine phosphokinase (CPK) assays, and echocardiography (ECHO). Those with only mechanism for BCI, i.e., none of the above risk factors (group 2), were admitted to a nonmonitored bed and had a follow-up ECG 24 hours later. A series of 315 patients were admitted with blunt chest trauma during a 17-month period; 144 patients were in group 1 and 171 in group 2. Overall, 22 patients were diagnosed as BCI (+BCI), defined as evolving ST segment changes, dysrhythmias, a CPK-MB index of >2.5, or hemodynamic instability. Of the 18 +BCI patients in group 1, all were symptomatic (i.e., none was included solely for a cardiac history, age, or need for general anesthesia). Six of these patients required treatment for dysrhythmias, hypotension, or pulmonary edema; one of whom died. Four patients with +BCI were in group 2 and had ECG changes at 24 hours; none of these four had any sequelae from their +BCI. None of the ECHOs demonstrated abnormal wall motion. Patients who sustain blunt chest trauma with a normal ECG, normal blood pressure, and no dysrhythmias on admission require no further intervention for BCI. Patients with ST segment changes, dysrhythmias, or hypotension following blunt chest trauma should be monitored for 24 hours, as this subgroup occasionally requires further treatment for complications of BCI. ECHO adds nothing as a screening test.

Taser X26 Discharges in Swine: Ventricular Rhythm Capture is Dependent on Discharge Vector

BACKGROUND Data from our previous studies indicate that Taser X26 stun devices can acutely alter cardiac function in swine. We hypothesized that most transcardiac discharge vectors would capture ventricular rhythm, but that other vectors, not traversing the heart, would fail to capture the ventricular rhythm. METHODS Using an Institutional Animal Care and Use Committee (IACUC) approved protocol, four Yorkshire pigs (25-36 kg) were anesthetized, paralyzed with succinylcholine (2 mg/kg), and then exposed to 10 second discharges from a police-issue Taser X26. For most discharges, the barbed darts were pushed manually into the skin to their full depth (12 mm) and were arranged in either transcardiac (such that a straight line connecting the darts would cross the region of the heart) or non-transcardiac vectors. A total of 11 different vectors and 22 discharge conditions were studied. For each vector, by simply rotating the cartridge 180-degrees in the gun, the primary current-emitting dart was changed and the direction of current flow during the discharge was reversed without physically moving the darts. Echocardiography and electrocardiograms (ECGs) were performed before, during, and after all discharges. p values < 0.05 were considered significant. RESULTS ECGs were unreadable during the discharges because of electrical interference, but echocardiography images clearly demonstrated that ventricular rhythm was captured immediately in 52.5% (31 of 59) of the discharges on the ventral surface of the animal. In each of these cases, capture of the ventricular rhythm with rapid ventricular contractions consistent with ventricular tachycardia (VT) or flutter was seen throughout the discharge. A total of 27 discharges were administered with transcardiac vectors and ventricular capture occurred in 23 of these discharges (85.2% capture rate). A total of 32 non-transcardiac discharges were administered ventrally and capture was seen in only eight of these (25% capture rate). Ventricular fibrillation (VF) was seen with two vectors, both of which were transcardiac. In the remaining animals, VT occurred postdischarge until sinus rhythm was regained spontaneously. CONCLUSIONS For most transcardiac vectors, Taser X26 caused immediate ventricular rhythm capture. This usually reverted spontaneously to sinus rhythm but potentially fatal VF was seen with two vectors. For some non-transcardiac vectors, capture was also seen but with a significantly (p < 0.0001) decreased incidence.

A method of determining peritoneal penetration in gunshot wounds to the abdomen.

BACKGROUND It has previously been shown that 98% of gunshot wounds that penetrate the peritoneal cavity cause injuries that require surgical repair. Many gunshot wounds in the vicinity of the abdomen (GSWA) may actually be tangential and not penetrate the peritoneal cavity at all. Patients with such wounds may not require laparotomy. It is important to determine which patients with a potential tangential GSWA actually have penetration of the peritoneal cavity to minimize negative laparotomies. This study was undertaken to determine the sensitivity, specificity, and accuracy of diagnostic peritoneal lavage (DPL) in the determination of peritoneal penetration for patients who sustain GSWA. METHODS DPL was performed for all patients who had sustained a GSWA in whom peritoneal penetration was unclear, i.e., patients whose GSWA appeared to be tangential, thoracoabdominal, or transpelvic and for whom a clear indication for laparotomy (shock, peritonitis, etc.) did not exist. Our threshold for a positive DPL was 10,000 red blood cells (RBC)/mm3. A prospective data base was kept with information on the location of the wound, DPL result, findings at laparotomy, and outcome. RESULTS During a 4-year period, 429 consecutive DPLs were performed for GSWA at our urban Level I trauma center. One hundred fifty DPLs were positive, with more than 10,000 RBC/mm3. Six of these patients were found to have no peritoneal penetration at laparotomy (false-positive). The remaining 144 patients with positive DPLs were found to have operative injuries (true-positive). Of the 279 patients with DPL counts less than 10,000 RBC/mm3, 2 developed indications for laparotomy and were found to have intraperitoneal injuries (false-negative). The remaining 277 patients had no peritoneal injuries (true-negative). This was demonstrated either by laparotomy done for another indication (n = 7) or by uneventful inpatient observation for 24 hours (n = 270). The sensitivity, specificity, and accuracy of DPL in determining peritoneal penetration in GSWA is therefore 99, 98, and 98%, respectively. CONCLUSION For patients who sustain GSWA for whom peritoneal penetration is unclear, DPL is a sensitive, specific, and accurate test to determine the need for laparotomy. It remains our test of choice when confronted with these patients.

Trans-mediastinal Gunshot Wounds: Are "Stable" Patients Really Stable?

Abstract Gunshot wounds that traverse the mediastinum frequently cause serious injury to the cardiac, vascular, pulmonary, and digestive structures contained within. Most patients present with unstable vital signs signifying the need for emergency operation. An occasional patient will present with stable vital signs. Work-ups for such a patient may range from surgical exploration to radiographic and endoscopic testing to mere observation. We report our experience with diagnostic work-up of the stable patient with a transmediastinal gunshot wound. All stable patients who present to our urban level I trauma center following a transmediastinal gunshot wound undergo diagnostic work-up consisting of chest radiograph, cardiac ultrasound, angiography, esophagoscopy, barium swallow, and bronchoscopy. The work-up is dependent on the trajectory of the missile. Information on these patients is kept in a prospective database maintained by the trauma attending physicians. This database was analyzed and comparisons were made using Student’s t-test and the Fisher exact c2 as appropriate. Over a 68-month period, 50 stable patients were admitted following a transmediastinal gunshot wound. All of these patients had a chest radiograph followed by one or more of the above tests. 8 patients (16%) were found to have a mediastinal injury (4 cardiac, 3 vascular, and 1 tracheo-esophageal) requiring urgent operation (group 1). The remaining 42 patients (84%) did not have a mediastinal injury (group 2). There was no difference between groups with respect to blood pressure, pulse, respiratory rate, pH, base deficit, or initial chest tube output. There was one death in each group, and three complications in group 2. Patients may appear stable following a transmediastinal gunshot wound, even when they have life-threatening injuries. There is no difference in vital signs, blood gas, or hemothorax to indicate which patients have serious injuries. We advocate continued aggressive work-up of these patients to avoid missing an injury with disastrous consequences.