Malek Tabbara

Fulminant Clostridium difficile colitis: Patterns of care and predictors of mortality

HYPOTHESIS There exist predictors of mortality and the need for colectomy among patients with fulminant Clostridium difficile colitis. DESIGN Retrospective study. SETTING Academic tertiary referral center. PATIENTS We reviewed the records of 4796 inpatients diagnosed as having C difficile colitis from January 1, 1996, to December 31, 2007, and identified 199 (4.1%) with fulminant C difficile colitis, as defined by the need for colectomy or admission to the intensive care unit for C difficile colitis. MAIN OUTCOME MEASURES Risk of inpatient mortality was determined by multivariate analysis according to clinical predictors, colectomy, and medical team. RESULTS The inhospital mortality rate for fulminant C difficile colitis was 34.7%. Independent predictors of mortality included the following: (1) age of 70 years or older, (2) severe leukocytosis or leukopenia (white blood cell count, >or=35 000/microL or <4000/microL) or bandemia (neutrophil bands, >or=10%), and (3) cardiorespiratory failure (intubation or vasopressors). When all 3 factors were present, the mortality rate was 57.1%; when all 3 were absent, the mortality rate was 0%. Patients who underwent colectomy had a trend toward decreased mortality rates (odds ratio, 0.49; 95% confidence interval, 0.21-1.1; P = .08). Among patients admitted primarily for fulminant C difficile colitis, care in the surgical department compared with the nonsurgical department resulted in a higher rate of operation (85.1% vs 11.2%; P < .001) and lower mortality rates (12.8% vs 39.3%; P = .001). Patients admitted directly to the surgical department had a shorter mean (SD) interval from admission to operation (0 vs 1.7 [2.8] days; P = .001). CONCLUSIONS Despite awareness and treatment, fulminant C difficile colitis remains a highly lethal disease. Reliable predictors of mortality exist and should be used to prompt aggressive surgical intervention. Survival rates are higher in patients who were cared for by surgical vs nonsurgical departments, possibly because of more frequent and earlier operations.

Pulmonary Embolism and Deep Venous Thrombosis in Trauma: Are They Related?

HYPOTHESIS Pulmonary embolism (PE) and deep venous thrombosis (DVT) in trauma are related. DESIGN Retrospective review of medical records. SETTING Academic level I trauma center. PATIENTS Trauma patients who underwent computed tomographic pulmonary angiography (CTPA) with computed tomographic venography (CTV) of the pelvic and proximal lower extremity veins over a 3-year period (January 1, 2004, to December 31, 2006) were reviewed. Data on demographics, injury type and severity, imaging findings, hospital length of stay, and mortality were collected. MAIN OUTCOME MEASURES Pulmonary embolism and DVT. RESULTS Among 247 trauma patients undergoing CTPA/CTV, PE was diagnosed in 46 (19%) and DVT in 18 (7%). Eighteen PEs were central (main or lobar pulmonary arteries), and 28 PEs were peripheral (segmental or subsegmental branches). Pulmonary embolism occurred within the first week of injury in two-thirds of patients. Seven patients with PE (4 femoral, 2 popliteal, and 1 iliac) had DVT. Pulmonary embolism was central in 5 patients and peripheral in 2 patients. No significant differences were noted in any of the examined variables between patients with PE having DVT and those not having DVT. CONCLUSIONS Few patients with PE have DVT of the pelvic or proximal lower extremity veins. Pulmonary embolism may not originate from these veins, as commonly believed, but instead may occur de novo in the lungs. These findings have implications for thromboprophylaxis and, particularly, the value of vena cava filters.

An evaluation of multidetector computed tomography in detecting pancreatic injury: results of a multicenter AAST study.

BACKGROUND Efforts to determine the suitability of low-grade pancreatic injuries for nonoperative management have been hindered by the inaccuracy of older computed tomography (CT) technology for detecting pancreatic injury (PI). This retrospective, multicenter American Association for the Surgery of Trauma-sponsored trial examined the sensitivity of newer 16- and 64-multidetector CT (MDCT) for detecting PI, and sensitivity/specificity for the identification of pancreatic ductal injury (PDI). METHODS Patients who received a preoperative 16- or 64-MDCT followed by laparotomy with a documented PI were enrolled. Preoperative MDCT scans were classified as indicating the presence (+) or absence (-) of PI and PDI. Operative notes were reviewed and all patients were confirmed as PI (+), and then classified as PDI (+) or (-). As all patients had PI, an analysis of PI specificity was not possible. PI patients formed the pool for further PDI analysis. As sensitivity and specificity data were available for PDI, multivariate logistic regression was performed for PDI patients using the presence or absence of agreement between CT and operative note findings as an independent variable. Covariates were age, gender, Injury Severity Score, mechanism of injury, presence of oral contrast, presence of other abdominal injuries, performance of the scan as part of a dedicated pancreas protocol, and image thickness < or =3 mm or > or =5 mm. RESULTS Twenty centers enrolled 206 PI patients, including 71 PDI (+) patients. Intravenous contrast was used in 203 studies; 69 studies used presence of oral contrast. Eight-nine percent were blunt mechanisms, and 96% were able to have their duct status operatively classified as PDI (+) or (-). The sensitivity of 16-MDCT for all PI was 60.1%, whereas 64-MDCT was 47.2%. For PDI, the sensitivities of 16- and 64-MDCT were 54.0% and 52.4%, respectively, with specificities of 94.8% for 16-MDCT scanners and 90.3% for 64-MDCT scanners. Logistic regression showed that no covariates were associated with an increased likelihood of detecting PDI for either 16- or 64-MDCT scanners. The area under the curve was 0.66 for the 16-MDCT PDI analysis and 0.77 for the 64-MDCT PDI analysis. CONCLUSION Sixteen and 64-MDCT have low sensitivity for detecting PI and PDI, while exhibiting a high specificity for PDI. Their use as decision-making tools for the nonoperative management of PI are, therefore, limited.

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.

Blunt pancreatoduodenal injury: A multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT)

OBJECTIVES To evaluate the safety of nonoperative management (NOM), to examine the diagnostic sensitivity of computed tomography (CT), and to identify missed diagnoses and related outcomes in patients with blunt pancreatoduodenal injury (BPDI). DESIGN Retrospective multicenter study. SETTING Eleven New England trauma centers (7 academic and 4 nonacademic). PATIENTS Two hundred thirty patients (>15 years old) with BPDI admitted to the hospital during 11 years. Each BPDI was graded from 1 (lowest) to 5 (highest) according to the American Association for the Surgery of Trauma grading system. MAIN OUTCOME MEASURES Success of NOM, sensitivity of CT, BPDI-related complications, length of hospital stay, and mortality. RESULTS Ninety-seven patients (42.2%) with mostly grades 1 and 2 BPDI were selected for NOM: NOM failed in 10 (10.3%), 10 (10.3%) developed BPDI-related complications (3 in patients in whom NOM failed), and 7 (7.2%) died (none related to failure of NOM). The remaining 133 patients were operated on urgently: 34 (25.6%) developed BPDI-related complications and 20 (15.0%) died. The initial CT missed BPDI in 30 patients (13.0%); 4 of them (13.3%) died but not because of the BPDI. The mortality rate in patients without a missed diagnosis was 8.8% (P = .50). There was no correlation between time to diagnosis and length of hospital stay (Spearman r = 0.06; P = .43). The sensitivity of CT for BPDI was 75.7% (76% for pancreatic and 70% for duodenal injuries). CONCLUSIONS The NOM of low-grade BPDI is safe despite occasional failures. Missed diagnosis of BPDI continues to occur despite advances in CT but does not seem to cause adverse outcomes in most patients.

Profound Hypothermia Decreases Cardiac Apoptosis Through Akt Survival Pathway

BACKGROUND Hypothermia increases the tolerable ischemia time for myocardium in hemorrhagic shock, but precise mechanisms are not clearly established. Here we studied activation of Akt cell survival pathway in a rodent model of emergency preservation and delayed resuscitation. STUDY DESIGN Wistar-Kyoto rats underwent 40% blood volume arterial hemorrhage during 10 minutes and were randomized into 2 groups based on core body temperatures (n = 7/group): hypothermia (15 degrees C) and normothermia (37 degrees C). Hypothermia was induced by infusing cold isotonic solution using cardiopulmonary bypass (CPB) setup. After reaching target body temperature, low-flow state (CPB flow rate of 20 mL/kg/min) was maintained for 60 minutes. Hypothermic rats were rewarmed to baseline temperature; all rats were resuscitated on CPB and monitored for 3 hours. The normothermia group underwent identical CPB management. Sham rats (no hemorrhage, no instrumentation) were used as controls (n = 7). Tissues were harvested at the end of experiment. RESULTS Induction of hypothermia increased survival rates (100% versus 0% in normothermia group). Western blot analysis of cardiac tissue revealed increased levels of phospho-Akt (active) in hypothermia and sham groups compared with the normothermia group (p < 0.05). Among downstream targets of Akt, phospho-GSK-3beta (inactive), phospho-Bad (inactive), beta-catenin, and Bcl-2 were considerably elevated in the hypothermia group compared with the normothermia group. Hypothermia also showed decreased activity of caspase-3 protein compared with normothermia (p < 0.05), suggesting decreased apoptosis. CONCLUSIONS Profound hypothermia increases survival in a rodent model of hemorrhagic shock and prolonged low-flow state. Hypothermia preserves Akt signaling pathway in cardiomyocytes with a concurrent decrease in cardiac apoptosis.

Putting life on hold-for how long? Profound hypothermic cardiopulmonary bypass in a Swine model of complex vascular injuries.

BACKGROUND Rapid induction of profound hypothermia for emergency preservation and resuscitation can improve survival from uncontrolled lethal hemorrhage in large animal models. We have previously demonstrated that profound hypothermia (10 degrees C) must be induced rapidly (2 degrees C/min) and reversed gradually (0.5 degrees C/min) for best results. However, the maximum duration of hypothermic arrest in a clinically relevant trauma model remains unknown. METHODS Uncontrolled lethal hemorrhage was induced in 22 swine by creating an iliac artery and vein injury, followed 30 minutes later (simulating transport time) by laceration of the descending thoracic aorta. Through a thoracotomy approach, a catheter was placed in the aorta, and cold organ preservation solution was infused using a roller pump to rapidly induce profound hypothermia (10 degrees C) which was maintained with low-flow cardiopulmonary bypass. Vascular injuries were repaired during the asanguinous hypothermic low flow period. Profound hypothermia was maintained (n = 10-12 per group) for either 60 minutes or 120 minutes. After repair of injuries, animals were rewarmed (0.5 degrees C/min) and resuscitated on cardiopulmonary bypass, and whole blood was infused during this period. Animals were monitored for 4 weeks for neurologic deficits, organ dysfunction, and postoperative complications. RESULTS The 4-week survival rates in 60- and 120-minute groups were 92% and 50%, respectively (p < 0.05). The surviving animals were neurologically intact and had no long-term organ dysfunction, except for one animal in the 120-minute group. The animals subjected to 120 minutes of hypothermia had significantly worse lactic acidosis, displayed markedly slower recovery, and had significantly higher rates of postoperative complications, including late deaths because of infections. CONCLUSION In a model of lethal injuries, rapid induction of profound hypothermia can prevent death. Profound hypothermia decreases but does not abolish metabolism. With current methods, the upper limit of hypothermic arrest in the setting of uncontrolled hemorrhage is 60 minutes.

MDCT for automated detection and measurement of pneumothoraces in trauma patients.

OBJECTIVE The size of a pneumothorax is an important index to guide the emergency treatment of trauma patients--chest tube drainage. The purpose of this study was to develop and validate an automated computer-aided volumetry scheme for detection and measurement of pneumothoraces for trauma patients imaged with MDCT. MATERIALS AND METHODS Three pigs and 68 trauma patients with at least one diagnosed occult pneumothorax (23 women and 45 men; age range, 14-89 years; mean age, 41 +/- 19 years) were selected for the development and validation of our computer-aided volumetry scheme for pneumothorax. Computer-aided volumetry of pneumothorax consisted of five automated steps: extraction of pleural region, detection of pneumothorax candidates, delineation of the detected pneumothorax candidates, reduction of false-positive findings, and report of the volumetric measurement of pneumothoraces. RESULTS In the animal study, our computer-aided volumetry scheme yielded a mean value of 24.27 +/- 0.64 mL (SD) compared with 25 mL of air volume manually injected in each scan. The correlation coefficients were 0.999 and 0.997 for the in vivo and ex vivo comparison, respectively. In the patient study, the sensitivity of our computer-aided volumetry scheme was 100% with a false-positive rate of 0.15 per case for 32 occult pneumothoraces > or = 25 mL. The correlation coefficient was 0.999 for manual volumetry comparison. This automated computer-aided volumetry scheme took approximately 3 minutes to finish the detection and measurement per case. CONCLUSION The results show that our computer-aided volumetry scheme provides an automated method for accurate and efficient detection and measurement of pneumothoraces in MDCT images of trauma patients.

Missed opportunities for primary repair in complicated acute diverticulitis

BACKGROUND Complicated acute diverticulitis (CAD) requiring an urgent operation is usually managed by fecal diversion (FD) despite reports suggesting that primary repair (PR) is safe. We aim to identify patient characteristics predicting successful PR and explore if patients are managed by FD despite the presence of such characteristics. METHODS We reviewed the medical records of 194 patients with CAD, requiring colectomy within 48 hr of admission from January 1996 to January 2006. Exclusion criteria included: admission for elective repair, treatment with antibiotics and/or percutaneous abscess drainage prior to operation (semi-elective), concurrent inflammatory disease, cancer, and inadequate documentation. Univariate and multivariate analysis identified independent predictors of PR. Patients who despite having these independent predictors underwent FD, were compared with the PR group. RESULTS Eighteen patients (9%) received PR. They were younger than FD patients, had a lower incidence of left-sided disease, were less frequently operated on within 4 hr of hospital arrival, and had less severe disease (Hinchey I or II). They also had shorter postoperative hospital stays (6.2 ± 2.3 vs 14.6 ±16.1; P = .002) and a trend towards a lower mortality (0% vs 6.8%; P = .38). The independent predictors of performing PR included: age less than 55 years, interval between admission and operation longer than 4 hr, and a Hinchey score I or II. There were 71 patients who had 2 (64) or all 3 (7) independent predictors of PR but still received FD. These patients were not different in any characteristic from the PR patients but had worse outcomes. CONCLUSION FD remains the prevailing operative method of choice of CAD. Despite the presence of factors favoring PR, many patients still receive FD and have worse outcomes. PR can be used more liberally in CAD.

Self-expanding hemostatic polymer for control of exsanguinating extremity bleeding

BACKGROUND Prehospital management of exsanguinating extremity injuries (EEI) includes direct compression or tourniquets or both. Direct compression may be ineffective in deep wounds and requires a person committed to compressing. Tourniquets may cause severe ischemic damage and may be ineffective in proximal wounds. This study aims to examine a new self-expanding hemostatic polymer (SEHP) for control of EEI. In contact with blood, the polymer absorbs the aqueous component of blood and exerts a tamponade effect by expanding against the walls of the wound cavity. METHODS Twenty-one pigs were subjected to a validated and reproducible model of lethal proximal extremity injury by transecting soft tissues and the femoral vessels. The pigs were left to bleed uncontrollably for 3 minutes and then randomized to receive either a standard compression dressing (Control group, N = 10) or SEHP (SEHP group, N = 11). After 5 minutes of manual compression, the dressing or SEHP were left in the wound and the animals resuscitated more than 2 hours. One animal in each group died soon after the injury before application of the dressings and was removed from final analysis. RESULTS SEHP animals had lower blood loss (1358 mL +/- 97 mL) than the Control animals (2028 mL +/- 177 mL, p = 0.006). The mortality was 55% in the Control group and 0% in the SEHP group (p = 0.006). CONCLUSION SEHP is a novel, light, and portable material to control EEI effectively. It does not require another person for compression nor does it compromise the circulation. As EEI occurs with alarming frequency in the battlefield, SEHP may not only present an optimal hemostatic method for military applications but also be useful in the civilian prehospital setting.