S. David Cho

Management and outcome of pneumatosis intestinalis.

BACKGROUND Pneumatosis intestinalis (PI), infiltration of gas into the bowel wall, has traditionally been associated with immediate operative intervention and a high mortality rate. METHODS We retrospectively reviewed the diagnosis and management of pneumatosis in an attempt to characterize the disease, and examined management strategies. RESULTS Ninety-seven patients had a computed tomography (CT) diagnosis of pneumatosis. The location of pneumatosis was as follows: 46% colon, 27% small bowel, 5% stomach, and 7% both small and large bowel. Fourteen patients also had portal venous gas and 6 (43%) of these patients died. Management strategy was non-operative in 52%, operative in 33%, and futile care in 15%. The overall mortality rate was 22% (16% operative, 6% non-operative, and 87% futile). Patients who died had a higher mean APACHE II score (25 vs 11, P <.001). CONCLUSIONS Approximately 50% of patients with pneumatosis can be successfully managed non-operatively. The combination of PI and portal venous gas may confer a higher mortality rate.

Thrombelastography versus AntiFactor Xa levels in the assessment of prophylactic-dose enoxaparin in critically ill patients.

BACKGROUND A standard dose of enoxaparin is frequently used for deep venous thrombosis (DVT) prophylaxis. Evidence suggests inconsistent bioavailability in intensive care unit (ICU) patients. Antifactor Xa activity (anti-Xa) has been used to monitor enoxaparin dosing but its accuracy and availability are problematic. Thrombelastography (TEG) is used to evaluate coagulation in diverse settings. The purpose of this study was to analyze whether TEG could be used to predict which enoxaparin-treated patients would develop DVT. METHODS Two hundred sixty-one simultaneous enoxaparin-active (active) and enoxaparin-neutralized (neutral) TEGs were performed in 61 surgical ICU patients over four consecutive days. Patient characteristics and anti-Xa were collected. DVT screening was per ICU protocol. RESULTS Mean (+/-SEM) age was 54 (+/-2.3) years and Acute Physiology and Chronic Health Evaluation II score was 17 (+/-0.7). There were 30 trauma and 31 general surgery patients (69% men). The DVT rate was 28%. Time to clot formation (R) and percent lysis at 30 minutes were different between active versus neutralized blood (p < 0.001). R time was 1.5 minutes shorter in patients with DVT versus those without (p < 0.001) indicating hypercoagulability in DVT patients. Anti-Xa levels were similar in patients with (0.135 +/- 0.012) and without (0.135 +/- 0.007) DVT (p = 0.97). There were no differences in age, body mass index, injury severity score, Acute Physiology and Chronic Health Evaluation II score, or trauma status between DVT and non-DVT groups. CONCLUSIONS TEG demonstrates differences between enoxaparin-neutralized and enoxaparin-active blood in ICU patients that may be used to guide dosing. TEG differentiates enoxaparin-treated patients who subsequently develop DVT while anti-Xa levels do not. TEG demonstrates an enoxaparin-related increase in fibrinolysis.

Lyophilized Plasma for Resuscitation in a Swine Model of Severe Injury

HYPOTHESIS Lyophilized plasma (LP) is as safe and effective as fresh frozen plasma (FFP) for resuscitation after severe trauma. DESIGN Multicenter animal study. SETTING Animal laboratories, 2 level I trauma centers. PARTICIPANTS Thirty-two Yorkshire crossbred swine. INTERVENTIONS Lyophilized plasma was analyzed for factor levels and clotting activity before lyophilization and after reconstitution. Swine were subjected to complex multiple trauma including extremity fracture, hemorrhage, severe liver injury, acidosis, and hypothermia. They were then resuscitated with FFP, LP, FFP and packed red blood cells (PRBCs) in a ratio of 1:1, or 1:1 LP and PRBCs. MAIN OUTCOME MEASURES Residual clotting activity of LP after reconstitution, swine mortality, hemodynamic measures, total blood loss, coagulation profiles, and inflammatory measures. RESULTS Lyophilization decreased clotting factor activity by an average of 14%. Survival and heart rate were similar between all groups. Swine resuscitated with LP had equivalent or higher mean arterial pressures. Swine treated with LP had similar coagulation profiles, plasma lactate levels, and postinjury blood loss compared with those treated with FFP. Swine treated with 1:1 FFP-PRBCs were similar to those treated with 1:1 LP-PRBCs. Resuscitation with LP resulted in a reduction in postresuscitation interleukin 6 expression compared with resuscitation with FFP. CONCLUSIONS The process of lyophilization and reconstitution of plasma reduces coagulation factor activity by 14%, without acute differences in blood loss. Lyophilized plasma can be used for resuscitation in a severe multiple trauma and hemorrhagic shock swine model with efficacy equal to that of FFP and with decreased interleukin 6 production.

Reproducibility of an Animal Model Simulating Complex Combat-Related Injury in a Multiple-Institution Format

We developed a complex combat-relevant model of abdominal and extremity trauma, hemorrhagic shock, hypothermia, and acidosis. We then simulated injury, preoperative, and operative phases. We hypothesized that this model is reproducible and useful for randomized multicenter preclinical trials. Yorkshire swine were anesthetized, intubated, and instrumented. They then underwent femur fracture, 60% total blood volume hemorrhage, a 30-min shock period, induced hypothermia to 33°C, and hemorrhage volume replacement with 3:1 isotonic sodium chloride solution (NS) at each of three centers. Hemodynamic parameters were measured continuously. Thromboelastography, arterial blood gas, and laboratory values were collected at baseline, after the shock period, and after NS replacement. Thirty-seven animals were used for model development. Eight (21%) died before completion of the study period. Twenty-nine survivors were included in the analysis. MAP (±SEM) after the shock period was 32 ± 2 mmHg and was similar between centers (P = 0.4). Mean pH, base deficit, and lactate levels were 7.29 ± 0.02, 8.20 ± 0.65 mmol/L, and 5.29 ± 0.44 mmol/L, respectively, after NS replacement. These were similar between centers (P > 0.05). Prothrombin time values increased significantly over time at all centers, reflecting a progressive coagulopathy (P < 0.02). Thromboelastography maximum amplitude values were similar among centers (P > 0.05) and demonstrated progressively weakened platelet interaction over time (P < 0.03). Hematocrit was similar after controlled hemorrhage (P = 0.15) and dilution (P = 0.9). The pH, lactate, base deficit, and coagulation tests reflect a severely injured state. A complex porcine model of polytrauma and shock canbe used for multi-institutional study with excellent reproducibility. A consistent severe injury profile was achieved, afterwhich experimental interventions can be applied. This is the first report of a reproducible multicenter trauma and resuscitation-related animal model.

Correlation of Missed Doses of Enoxaparin With Increased Incidence of Deep Vein Thrombosis in Trauma and General Surgery Patients

IMPORTANCE Enoxaparin sodium is widely used for deep vein thrombosis (DVT) prophylaxis, yet DVT rates remain high in the trauma and general surgery populations. Missed doses during hospitalization are common. OBJECTIVE To determine if missed doses of enoxaparin correlate with DVT formation. DESIGN, SETTING, AND PARTICIPANTS Data were prospectively collected among 202 trauma and general surgery patients admitted to a level I trauma center. MAIN OUTCOMES AND MEASURES Deep vein thrombosis screening was performed using a rigorous standardized protocol. RESULTS The overall incidence of DVT was 15.8%. In total, 58.9% of patients missed at least 1 dose of enoxaparin. The DVTs occurred in 23.5% of patients who missed at least 1 dose and in 4.8% of patients who did not (P < .01). On univariate analysis, the need for mechanical ventilation (71.8% vs 44.1%), the performance of more than 1 operation (59.3% vs 40.0%), and male sex (75% vs 56%) were associated with DVT formation (P < .05 for all). A bivariate logistic regression was then performed, which revealed age 50 years or older and interrupted enoxaparin therapy as the only independent risk factors for DVT formation. The DVT rate did not differ between trauma and general surgery populations or in patients receiving once-daily vs twice-daily dosing regimens. CONCLUSIONS AND RELEVANCE Interrupted enoxaparin therapy and age 50 years or older are associated with DVT formation among trauma and general surgery patients. Missed doses occur commonly and are the only identified risk factor for DVT that can be ameliorated by physicians. Efforts to minimize interrupted enoxaparin prophylaxis in patients at risk for DVT should be optimized.

A novel highly porous silica and chitosan-based hemostatic dressing is superior to HemCon and gauze sponges.

BACKGROUND Hemostatic dressings have become increasingly popular as the optimal initial treatment for severe hemorrhage. The purpose of this study was to compare the hemostatic properties of a novel highly porous silica and chitosan-based dressing (TraumaStat) to HemCon, and gauze dressing in a severe groin injury model in swine. METHODS Thirty swine were blindly randomized to receive TraumaStat, HemCon, or standard gauze dressing for hemostatic control. A complex groin injury involving complete transaction of the femoral artery and vein was made. After 30 seconds of uncontrolled hemorrhage, the randomized dressing was applied and pressure was held for 5 minutes. Fluid resuscitation was initiated to achieve and maintain the baseline mean arterial pressure and the wound was inspected for bleeding. Failure of hemostasis was defined as pooling of blood outside of the wound. Animals were then monitored for 120 minutes and surviving animals were euthanized. RESULTS Blood loss before treatment was similar between groups (p > 0.1). TraumaStat had one failure, compared with five for gauze, and eight for HemCon (p = 0.005, TraumaStat vs. HemCon). TraumaStat significantly reduced median blood loss when compared with both HemCon and gauze (117 vs. 774 and 268 mL respectively, p < 0.05). At study conclusion, TraumaStat animals had a greater median hematocrit than both HemCon (24 vs. 19, p = 0.033), and gauze (24 vs. 19, p = 0.049) animals. Median volume of fluid resuscitation and mortality were not different between groups (p > 0.1). CONCLUSIONS TraumaStat was superior to HemCon and gauze dressings in controlling bleeding from a severe groin injury. TraumaStat may be a better hemostatic dressing for control of active hemorrhage than current standards of care.

A highly porous silica and chitosan-based hemostatic dressing is superior in controlling hemorrhage in a severe groin injury model in swine

BACKGROUND This study compared the efficacy of 3 hemostatic dressings in a severe groin injury model in swine. METHODS Twenty-three swine received TraumaStat (OreMedix, Lebanon, OR), Chitoflex (HemCon, Inc., Portland, OR), or standard gauze for hemostasis. Complete femoral vessel transections were followed by 30 seconds of uncontrolled hemorrhage. The groin was packed with the randomized dressing followed by 30 seconds of compression. Resuscitation with lactated Ringers solution commenced immediately postcompression to the preinjury mean arterial blood pressure. Hemostasis failure was defined as blood pooling outside the wound. Animals were monitored and maintained at the preinjury mean arterial pressure for 120 minutes, culminating with euthanization. RESULTS There were no differences in baseline values between groups. TraumaStat resulted in less hemostasis failure (P < .05), decreased postcompression blood loss (P < .05), and decreased fluid requirement (P < .05). No significant difference in mortality was seen between groups. There were no differences between standard gauze and Chitoflex with respect to dressing failure, posttreatment blood loss, or fluid resuscitation. CONCLUSIONS TraumaStat performed significantly better than Chitoflex and standard gauze in controlling hemorrhage from a severe groin injury in swine.

Management of colonic injuries in the combat theater.

PURPOSE: Combat injuries are more often associated with blast, penetrating, and high-energy mechanisms than civilian trauma, generating controversy about the management of combat colonic injury. Despite implementation of mandatory colostomy in World War II, recent civilian data suggest that primary repair without diversion is safe and feasible. This study describes the modern management of battle-related colonic injuries and seeks to determine whether management strategy affects early complications. METHODS: Records from the combat theater (downrange) and tertiary referral center in Germany were retrospectively reviewed from 2005 to 2006. Patient characteristics, management strategy, treatment course, and early complications were recorded. Comparison groups by management strategy were as follows: primary repair, diversion, and damage control. RESULTS: A total of 133 (97% male) patients sustained colonic injuries from penetrating (71%), blunt (5%), and blast (23%) mechanisms. Average injury severity score was 21 and length of stay in the referral center was 7.1 days. Injury distribution was 21% ascending, 21% descending, 15% transverse, 27% sigmoid, and 25% rectum. Downrange complications for primary repair, initial ostomy, and damage control groups were 14%, 15%, and 30%, respectively. On discharge from the center, 62% of patients had undergone a diversion. The complication rate was 18% overall and was unrelated to management strategy (P = .16). Multivariate analysis did not identify independent predictors of complications. CONCLUSION: Early complications were similar by mechanism, anatomic location, severity of injury, and management strategy. More diversions were performed for rectosigmoid injury. Good surgical judgment allows for low morbidity and supports primary repair in selected cases. Damage control surgery is effective in a multinational theater of operations.

Blood volume analysis can distinguish true anemia from hemodilution in critically ill patients.

BACKGROUND Peripheral hematocrit (pHct) is traditionally used as a marker for blood loss. In critically ill patients who are fluid resuscitated, pHct may not adequately represent red blood cell volume (RBCV). We hypothesize that the use of pHct alone may overestimate anemia, potentially leading to unnecessary interventions. METHODS Patients admitted to the intensive care unit underwent blood volume analysis. Serial blood samples were collected after injection of I-albumin. Samples were then processed by the Blood Volume Analyzer-100. RBCV and total blood volume (TBV) were calculated using the directly measured plasma volume (PV) and pHct. A computed normalized hematocrit (nHct) adjusts pHct to the patients ideal blood volume. RESULTS Thirty-six patients (21 men), aged 49.8 years ± 18.4 years, Acute Physiology And Chronic Health Evaluation II score 14.9 ± 8.1, and injury severity score 29.4 ± 12.4 had 84 blood volume analyses performed on 3 consecutive days. Using ratios of TBV compared with ideal TBV, patients were stratified into three separate groups: hypovolemic (16 of 84), normovolemic (23 of 84), and hypervolemic (45 of 84). Mean differences between pHct and nHct in each group were 4.5% ± 3.1% (p≤0.01), 0.0% ± 1.2% (p=0.85), and -6.5% ± 4.1% (p≤0.01), respectively. pHct, when compared with nHct, diagnosed anemia (Hct <30) nearly equal within the hypovolemic and normovolemic groups. However, pHct overdiagnosed anemia in 46.7% of hypervolemic patients. CONCLUSION Use of blood volume analysis in critically ill patients may help to distinguish true anemia from hemodilution, potentially preventing unnecessary interventions.

The use of lyophilized plasma in a severe multi-injury pig model

Shock and severe tissue injury lead to an endogenous coagulopathy mediated by activation of Protein C and hyperfibrinolysis known as acute traumatic coagulopathy. Together, hemodilution, acidosis, inflammation, and hypothermia result in a global trauma‐induced coagulopathy. Coagulopathy in trauma is associated with mortality. Early and effective hemostatic resuscitation is critical in restoring perfusion, correcting coagulopathy, and saving lives in exsanguinating trauma. Lyophilized plasma (LP) provides a logistically superior alternative to fresh frozen plasma (FFP).