Homer C. Tien

Multi-drug resistant Acinetobacter infections in critically injured Canadian forces soldiers.

BackgroundMilitary members, injured in Afghanistan or Iraq, have returned home with multi-drug resistant Acinetobacter baumannii infections. The source of these infections is unknown.MethodsRetrospective study of all Canadian soldiers who were injured in Afghanistan and who required mechanical ventilation from January 1 2006 to September 1 2006. Patients who developed A. baumannii ventilator associated pneumonia (VAP) were identified. All A. baumannii isolates were retrieved for study patients and compared with A. baumannii isolates from environmental sources from the Kandahar military hospital using pulsed-field gel electrophoresis (PFGE).ResultsDuring the study period, six Canadian Forces (CF) soldiers were injured in Afghanistan, required mechanical ventilation and were repatriated to Canadian hospitals. Four of these patients developed A. baumannii VAP. A. baumannii was also isolated from one environmental source in Kandahar – a ventilator air intake filter. Patient isolates were genetically indistinguishable from each other and from the isolates cultured from the ventilator filter. These isolates were resistant to numerous classes of antimicrobials including the carbapenems.ConclusionThese results suggest that the source of A. baumannii infection for these four patients was an environmental source in the military field hospital in Kandahar. A causal linkage, however, was not established with the ventilator. This study suggests that infection control efforts and further research should be focused on the military field hospital environment to prevent further multi-drug resistant A. baumannii infections in injured soldiers.

An evaluation of tactical combat casualty care interventions in a combat environment.

BACKGROUND Tactical combat casualty care (TCCC) is a system of prehospital trauma care designed for the combat environment. Although widely adopted, very few studies have reported on how TCCC interventions are actually delivered on the battlefield, from a quality of care perspective. STUDY DESIGN This was a prospective study of all trauma patients treated at the Role 3 multinational medical unit (MMU) at Kandahar Airfield Base from February 7, 2006 to May 30, 2006. Primary outcomes were whether or not two TCCC interventions were underused, overused, or misused. Interventions studied were needle decompression of tension pneumothoraces and tourniquet application for exsanguinating extremity injuries. RESULTS One hundred thirty-four trauma patients were treated at the Role 3 MMU during the study period. Six patients had eight tourniquets applied. Five tourniquets were applied to four patients appropriately and saved their lives. There was one case of misuse where a venous tourniquet was applied. There was one case of overuse where one patient had two tourniquets placed for 4 hours on extremities with no vascular injury. There were seven cases where needle decompression was underused: seven patients presented with vital signs absent with no needle decompression. There was one case of overuse of needle decompression. There were seven cases of misuse where the patients were decompressed too medially. CONCLUSIONS Tourniquets save lives. Needle decompression can save lives, but is usually performed in patients with multiple critical injuries. TCCC instructors must reinforce proper techniques and indications for each procedure to ensure that the quality of care provided to injured soldiers on the battlefield remains high.

Clotting Factor Deficiency in Early Trauma-Associated Coagulopathy

BACKGROUND Coagulopathic bleeding is a leading cause of in-hospital death after injury. A recently proposed transfusion strategy calls for early and aggressive frozen plasma transfusion to bleeding trauma patients, thus addressing trauma-associated coagulopathy (TAC) by transfusing clotting factors (CFs). This strategy may dramatically improve survival of bleeding trauma patients. However, other studies suggest that early TAC occurs by protein C activation and is independent of CF deficiency. This study investigated whether CF deficiency is associated with early TAC. METHODS This is a prospective observational cohort study of severely traumatized patients (Injury Severity Score ≥ 16) admitted shortly after injury, receiving minimal fluids and no prehospital blood. Blood was assayed for CF levels, thromboelastography, and routine coagulation tests. Critical CF deficiency was defined as ≤ 30% activity of any CF. RESULTS Of 110 patients, 22 (20%) had critical CF deficiency: critically low factor V level was evident in all these patients. International normalized ratio, activated prothrombin time, and, thromboelastography were abnormal in 32%, 36%, and 35%, respectively, of patients with any critically low CF. Patients with critical CF deficiency suffered more severe injuries, were more acidotic, received more blood transfusions, and showed a trend toward higher mortality (32% vs. 18%, p = 0.23). Computational modeling showed coagulopathic patients had pronounced delays and quantitative deficits in generating thrombin. CONCLUSIONS Twenty percent of all severely injured patients had critical CF deficiency on admission, particularly of factor V. The observed factor V deficit aligns with current understanding of the mechanisms underlying early TAC. Critical deficiency of factor V impairs thrombin generation and profoundly affects hemostasis.

Societal Costs of Inappropriate Emergency Department Thoracotomy

BACKGROUND Emergency department (ED) thoracotomy can be lifesaving. It can also lead to resource waste and exposure to blood-borne infections. We investigated the frequency with which ED thoracotomy was performed for inappropriate indications and the resulting societal costs. STUDY DESIGN This retrospective cohort study examined all trauma patients admitted directly from the scene of injury from 1992 to 2009 who underwent ED thoracotomy. The main outcomes included inappropriate ED thoracotomy. Secondary outcomes included resource use and societal costs for performing ED thoracotomy for improper indications. Specifically, we analyzed for operating room use, blood transfusions, ICU and hospital stay, needlestick injuries, survivor rate, and neurological outcomes in this group. RESULTS One hundred and twenty-three patients underwent ED thoracotomy during the study period. Of those, 63 (51%) were considered inappropriate. In this group, we observed no survivors, none became organ donors, 3 cases of needlestick injuries to health care providers occurred, and 335 U of blood products were used in their care. Also, 4 patients of 63 survived to the operating room and required a total of 6 separate operating room visits. Three of these patients had an ICU stay of 1 day and 1 died on day 5. CONCLUSIONS ED thoracotomy should be reserved for potentially salvageable patients, but discouraged for other indications. From the societal point of view, inappropriate use of the procedure resulted in substantial costs and waste of resources, exposure of health care providers to possible blood-borne infections, and offered no survival benefit.

Hypoperfusion in severely injured trauma patients is associated with reduced coagulation factor activity.

BACKGROUND Recent studies have shown that acute traumatic coagulopathy is associated with hypoperfusion, increased plasma levels of soluble thrombomodulin, and decreased levels of protein C but with no change in factor VII activity. These findings led to the hypothesis that acute traumatic coagulopathy is primarily due to systemic anticoagulation, by activated protein C, rather than decreases in serine protease activity. This study was designed to examine the effect of hypoperfusion secondary to traumatic injury on the activity of coagulation factors. METHODS Post hoc analysis of prospectively collected data on severely injured adult trauma patients presenting to a single trauma center within 120 minutes of injury. Venous blood was analyzed for activity of factors II, V, VII, VIII, IX, X, and XI. Base deficit from arterial blood samples was used as a marker of hypoperfusion. RESULTS Seventy-one patients were identified. The activity of factors II, V, VII, IX, X, and XI correlated negatively with base deficit, and after stratification into three groups, based on the severity of hypoperfusion, a statistically significant dose-related reduction in the activity of factors II, VII, IX, X, and XI was observed. Hypoperfusion is also associated with marked reductions in factor V activity levels, but these appear to be relatively independent of the degree of hypoperfusion. The activity of factor VIII did not correlate with base deficit. CONCLUSIONS Hypoperfusion in trauma patients is associated with a moderate, dose-dependent reduction in the activity of coagulation factors II, VII, IX, X, and XI, and a more marked reduction in factor V activity, which is relatively independent of the severity of shock. These findings suggest that the mechanisms underlying decreased factor V activity--which could be due to activated protein C mediated cleavage, thus providing a possible link between the proposed thrombomodulin/thrombin-APC pathway and the serine proteases of the coagulation cascade--and the reductions in factors II, VII, IX, X, and XI may differ. Preservation of coagulation factor activity in the majority of normally and moderately hypoperfused patients suggests that aggressive administration of plasma is probably only indicated in severely hypoperfused patients. Markers of hypoperfusion, such as base deficit, might be better and more readily available predictors of who require coagulation support than international normalized ratio or activated partial thromboplastin time.

Causes of Death in Canadian Forces Members Deployed to Afghanistan and Implications on Tactical Combat Casualty Care Provision

BACKGROUND As part of its contribution to the Global War on Terror and North Atlantic Treaty Organizations International Security Assistance Force, the Canadian Forces deployed to Kandahar, Afghanistan, in 2006. We have studied the causes of deaths sustained by the Canadian Forces during the first 28 months of this mission. The purpose of this study was to identify potential areas for improving battlefield trauma care. METHODS We analyzed autopsy reports of Canadian soldiers killed in Afghanistan between January 2006 and April 2008. Demographic characteristics, injury data, location of death within the chain of evacuation, and cause of death were determined. We also determined whether the death was potentially preventable using both explicit review and implicit review by a panel of trauma surgeons. RESULTS During the study period, 73 Canadian Forces members died in Afghanistan. Their mean age was 29 (+/-7) years and 98% were male. The predominant mechanism of injury was explosive blast, resulting in 81% of overall deaths during the study period. Gunshot wounds and nonblast-related motor vehicle collisions were the second and third leading mechanisms of injury causing death. The mean Injury Severity Score was 57 (+/-24) for the 63 study patients analyzed. The most common cause of death was hemorrhage (38%), followed by neurologic injury (33%) and blast injuries (16%). Three deaths were deemed potentially preventable on explicit review, but implicit review only categorized two deaths as being potentially preventable. CONCLUSIONS The majority of combat-related deaths occurred in the field (92%). Very few deaths were potentially preventable with current Tactical Combat Casualty interventions. Our panel review identified several interventions that are not currently part of Tactical Combat Casualty that may prevent future battlefield deaths.

The Natural History of Trauma-related Coagulopathy: Implications for Treatment

BACKGROUND Hemorrhage is a leading cause of death in trauma patients and coagulopathy is a significant contributor. Although the exact mechanisms of trauma-associated coagulopathy (TAC) are incompletely understood, hemostatic resuscitation strategies have been developed to treat TAC. Our study sought to identify which trauma patients develop TAC and the factors associated with its development, to describe the natural history of TAC, and to identify patients with TAC who may not require hemostatic resuscitation. METHODS Patients with early coagulopathy (International Normalized Ratio >1.3) who were admitted directly from the scene within 1 hour of injury were identified in our institutional trauma registry. We analyzed these data for the presence of TAC, predictors of early and delayed TAC, and evolution of TAC during the first 24 hours of admission. RESULTS Of 2,473 patients, 290 (12%) had early TAC (International Normalized Ratio >1.3) and 271 (11%) developed delayed TAC. Multivariate analysis identified female gender (odds ratio [OR] 1.25 [1.11-1.41]), lower pH (OR 0.08 [0.015-0.47]), lower hemoglobin (OR 0.96 [0.95-0.97]), lower temperature (OR 0.82 [0.70-0.95]), and blunt mechanism (OR 0.49 [0.33-0.71]) as factors significantly associated with development of early TAC. Progression of early TAC occurred in 64%, and these patients had more severe abdominal injury and received more emergency room crystalloid. Of patients with early TAC who did not receive fresh frozen plasma, only 49% developed worsening coagulopathy. Patients with isolated intracranial hemorrhage had higher rates of bleeding progression (75% vs. 20%, p < 0.005) in the presence of early TAC. CONCLUSIONS TAC may appear in an early or delayed form and its presence and progression are associated with a number of identifiable factors. Although TAC commonly progresses, it also resolves spontaneously in many patients. Further research is required to identify which patients with TAC require hemostatic treatment, although those with intracranial hemorrhages seem to warrant aggressive therapy.

Design and preliminary results of a pilot randomized controlled trial on a 1:1:1 transfusion strategy: the trauma formula-driven versus laboratory-guided study.

BACKGROUND Retrospective reviews have recently shown an survival benefit for adopting a resuscitation strategy that transfuses plasma and platelets at a near 1:1 ratio with red blood cells (RBCs). However, a randomized controlled trial on the topic is lacking. We report on the design and preliminary results of our ongoing randomized control pilot trial (ClinicalTrial.gov NCT00945542). METHODS This is a 2-year feasibility randomized control trial at a single tertiary trauma center. Bleeding trauma patients were randomized to either a laboratory-driven or a formula-driven (1 plasma:1 platelet:1 RBC) transfusion protocols. Feasibility was assessed by analyzing for ability to enroll patients, appropriate activation of transfusion protocols, time to transfusion of each type of blood product, laboratory turnaround time, ratio of blood products transfused, and wastage of blood products. RESULTS From July 6, 2009, to May 31, 2010, n = 18 patients were randomized and included in the study. Issues that we noted were the need to do postrandomization exclusions, the need to have rapid and accurate predictors of massive bleeding to enroll patients quickly, and the need to have waived consent for study participation. As well, we noted that the logistics of administering 1:1:1 were formidable and required rapid access to thawed plasma. Similarly, challenges in the control arm of such a study included the turnaround time for obtaining laboratory results. CONCLUSION Despite major challenges, our initial experience suggests that with an organized system, it is possible to prospectively randomize massively bleeding trauma patients. The accomplishment of high ratios of plasma to RBCs is challenging with current thawing methods and unavailability of thawed plasma in Canada. Longer shelf-life for plasma and faster plasma thawing microwaves should overcome some of these obstacles. For a laboratory-guided transfusion protocol, massive transfusion protocols should be in place with faster turnaround time for coagulation tests. Finally, further research on predictors of massive transfusion is needed.

Physical rehabilitation of the critically ill trauma patient in the ICU.

Objectives:To 1) review the existing evidence for early mobilization of the critically ill patients in the ICU with polytrauma; 2) provide intensivists with an introduction to the biomechanics, physiology, and nomenclature of injuries; 3) summarize the evidence for early mobilization in each anatomic area; and 4) provide recommendations for the mobilization of these patients. Data Sources:A literature search of the MEDLINE and EMBASE databases for articles published in English between 1980 and 2011. Study Selection:Studies pertaining to physical therapy and rehabilitation in trauma patients were selected. Articles were excluded if they dealt with pediatrics, geriatrics, burn injuries, isolated hand injuries, chronic (i.e., not acute) injuries, nontraumatic conditions, and pressure/decubitus ulcers, were in a language other than English, were published only in abstract form, were letters to the editor, were case reports, or were published prior to 1980. Data Extraction:Reviewers extracted data and summarized results according to anatomical areas. Data Synthesis:Of 1,411 titles and abstracts, 103 met inclusion criteria. We found no articles specifically addressing the rehabilitation of polytrauma patients in the ICU setting or patients with polytrauma in general. We summarized the articles addressing the role of mobilization for specific injuries and treatments. We used this evidence, in combination with biologic rationale and physician and surgeon experience and expertise, to summarize the important considerations when providing physical therapy to these patients in the ICU setting. Conclusions:There is a paucity of evidence addressing the role of early mobilization of ICU patients with polytrauma and patients with polytrauma in general. Evidence for the beneficial role of early mobilization of specific injuries exists. Important considerations when applying a strategy of early physical therapy and mobilization to this distinctive patient group are summarized.

Detection of significant bowel and mesenteric injuries in blunt abdominal trauma with 64-slice computed tomography.

BACKGROUND Approximately 5% of blunt abdominal trauma patients experience blunt bowel and mesenteric injuries (BBMIs). The diagnosis may be elusive as computed tomography (CT) can occasionally miss these injuries. Recent advancements in CT technology, however, may improve detection rates. This study will assess the false-negative rate of BBMI using a 64-slice computed tomographic scanner in adults with blunt abdominal trauma. METHODS All blunt abdominal trauma patients with laparotomy confirmed BBMI were retrospectively identified within a 5-year period at a Level I trauma center. Only patients who underwent preoperative abdominal CT were included. CT reports were examined specifically for findings suggestive of BBMI and compared with operative findings. A completely normal computed tomographic scan result as interpreted by a staff radiologist but operative findings of BBMI was considered a false negative. RESULTS One hundred ninety five cases of laparotomy-proven BBMI were identified from the trauma registry, of which 68 patients met study inclusion criteria. All study patients had free fluid present on CT. As a result, there were no false-negative computed tomographic scan results for BBMI. Four patients had isolated small amounts of free fluid without any additional suggestive CT findings of BBMI or solid-organ injury. Mesenteric or bowel hematomas and bowel wall thickening were present in 57% and 50% of cases, respectively. CONCLUSION The false-negative rates of BBMI may be reduced with a 64-slice computed tomographic scan. In this study, all patients had free fluid identified on CT. Consequently, even minimal free fluid remains relevant in patients with blunt abdominal injury. LEVEL OF EVIDENCE Diagnostic test, level III.