Kimberly A. Davis

Penetrating colon injuries requiring resection: Diversion or primary anastomosis? An AAST prospective multicenter study

BACKGROUND The management of colon injuries that require resection is an unresolved issue because the existing practices are derived mainly from class III evidence. Because of the inability of any single trauma center to accumulate enough cases for meaningful statistical analysis, a multicenter prospective study was performed to compare primary anastomosis with diversion and identify the risk factors for colon-related abdominal complications. METHODS This was a prospective study from 19 trauma centers and included patients with colon resection because of penetrating trauma, who survived at least 72 hours. Multivariate logistic regression analysis was used to compare outcomes in patients with primary anastomosis or diversion and identify independent risk factors for the development of abdominal complications. RESULTS Two hundred ninety-seven patients fulfilled the criteria for inclusion and analysis. Overall, 197 patients (66.3%) were managed by primary anastomosis and 100 (33.7%) by diversion. The overall colon-related mortality was 1.3% (four deaths in the diversion group, no deaths in the primary anastomosis group, p = 0.012). Colon-related abdominal complications occurred in 24% of all patients (primary repair, 22%; diversion, 27%; p = 0.373). Multivariate analysis including all potential risk factors with p values < 0.2 identified three independent risk factors for abdominal complications: severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis. The type of colon management was not found to be a risk factor. Comparison of primary anastomosis with diversion using multivariate analysis adjusting for the above three identified risk factors or the risk factors previously described in the literature (shock at admission, delay > 6 hours to operating room, penetrating abdominal trauma index > 25, severe fecal contamination, and transfusion of > 6 units blood) showed no statistically significant difference in outcome. Similarly, multivariate analysis and comparison of the two methods of colon management in high-risk patients showed no difference in outcome. CONCLUSION The surgical method of colon management after resection for penetrating trauma does not affect the incidence of abdominal complications, irrespective of associated risk factors. Severe fecal contamination, transfusion of > or = 4 units of blood within the first 24 hours, and single-agent antibiotic prophylaxis are independent risk factors for abdominal complications. In view of these findings, the reduced quality of life, and the need for a subsequent operation in colostomy patients, primary anastomosis should be considered in all such patients.

Ventilator-associated pneumonia: a review.

Ventilator-associated pneumonia is the most frequent intensive care unit (ICU)-related infection in patients requiring mechanical ventilation. In contrast to other ICU-related infections, which have a low mortality rate, the mortality rate for ventilator-associated pneumonia ranges from 20% to 50%. These clinically significant infections prolong duration of mechanical ventilation and ICU length of stay, underscoring the financial burden these infections impose on the health care system. The causes of ventilator-associated pneumonia are varied and differ across different patient populations and different types of ICUs. This varied presentation underscores the need for the intensivist treating the patient with ventilator-associated pneumonia to have a clear knowledge of the ambient microbiologic flora in their ICU. Prevention of this disease process is of paramount importance and requires a multifaceted approach. Once a diagnosis of ventilator-associated pneumonia is suspected, early broad-spectrum antibiotic administration decreases morbidity and mortality and should be based on knowledge of the sensitivities of common infecting organisms in the ICU. De-escalation of therapy, once final culture results are available, is necessary to minimize development of resistant pathogens. Duration of therapy should be based on the patient’s clinical response, and every effort should be made to minimize duration of therapy, thus further minimizing the risk of resistance.

Ten year experience of burn, trauma, and combined burn/trauma injuries comparing outcomes.

BACKGROUND Percent total body surface area (TBSA) burn, inhalation injury (INH), and age all have been shown to be independent predictors of mortality in burn victims. Little is known regarding patients sustaining combined thermal and mechanical injuries in relation to either injury sustained in isolation or with regard to these variables. This descriptive study profiles the 10-year experience of a single American Burn Association/American College of Surgeons verified Level I trauma and burn center and the treatment of this patient population. METHODS A retrospective review of all burn and trauma patients admitted between 1990 and 2000. Patients were divided into three groups; Burn only (B), Trauma only (T), and combined Burn/Trauma (B/T). Groups were compared with respect to age, TBSA burn, length of stay (LOS), Injury Severity Score (ISS), INH and mortality. These groups were then compared with B, T and B/T patients from the National Burn Repository (NBR) and National Trauma Data Bank (NTDB). Students t test and chi tests were performed, as well as multiple logistic regression to identify independent predictors of mortality. p <0.05 was considered significant. RESULTS Through our trauma registry, 24,093 patients were identified (T=22,284, B=1717 and B/T=92). When comparing B and T, there was no difference in age, LOS, ISS, or mortality to those patients in the NBR or NTDB. B/T patients showed significantly increased percentage with INH (B/T=44.5% versus 11%), increased LOS (B/T=18 days versus 13.7 B and 5.3 T) and increased mortality (B/T=28.3% versus 9.8% B and 4.3% T). B/T were also significantly older (B/T=40.1 years versus 31.0 B and 35.1 T). When these variables are compared with the NBR and the NTDB benchmarks, mortality (28.3% versus 11.6% NBR and 7.0% NTDB) and ISS (23 versus 11.7 NTDB) were significantly higher with no difference in age (40.1 versus 33.4 NTDB, 35.9 NBR), LOS (18 days versus 23.3 NBR) or TBSA (20.8% versus 19.5% NBR). Multiple logistic regression comparing TBSA, age, ISS and INH of survivors versus non-survivors identified only ISS as an independent predictor of mortality. CONCLUSION B combined with T presents a rare injury pattern that has a synergistic effect on mortality. Physicians and caregivers should be aware of a 2-3 fold increase in the incidence of INH in this population, and increased mortality despite similar TBSA burned when compared with patients with B as the sole mechanism; ISS appears to be an independent predictor of mortality in this combined injury pattern.

Use of presumptive antibiotics following tube thoracostomy for traumatic hemopneumothorax in the prevention of empyema and pneumonia--a multi-center trial.

OBJECTIVE To determine whether presumptive antibiotics reduce the risk of empyema or pneumonia following tube thoracostomy for traumatic hemopneumothorax. METHODS A prospective, randomized, double-blind trial was performed comparing the use of cefazolin for duration of tube thoracostomy placement (Group A) versus 24 hours (Group B) versus placebo (Group C). RESULTS A total of 224 patients received 229 tube thoracostomies. Logistic regression analysis revealed that duration of tube placement and thoracic acute injury score were predictive of empyema (p <0.05). Empyema tended to occur more frequently in patients with penetrating injuries (p=0.09). chi analysis showed pneumonia occurred significantly more frequently in blunt than penetrating injuries (p <0.05). Presumptive antibiotic use did not significantly effect the incidence of empyema or pneumonia, although no empyemas occurred in Group A. CONCLUSIONS The incidence of empyema was low and the use of presumptive antibiotics did not appear to reduce the risk of empyema or pneumonia.

Handsewn versus stapled anastomosis in penetrating colon injuries requiring resection: a multicenter study.

BACKGROUND Although the use of stapling devices in elective colon surgery has been shown to be as safe as handsewn techniques, there have been concerns about their safety in emergency trauma surgery. The purpose of this study was to compare stapled with handsewn colonic anastomosis following penetrating trauma. METHODS This was a prospective multicenter study and included patients who underwent colon resection and anastomosis following penetrating trauma. Multivariate logistic regression analysis was used to identify independent risk factors for abdominal complications and compare outcomes between stapled and handsewn repairs. RESULTS Two hundred seven patients underwent colon resection and primary anastomosis. In 128 patients (61.8%) the anastomosis was performed with handsewing and in the remaining 79 (38.2%) with stapling devices. There were no colon-related deaths and the overall incidence of colon-related abdominal complications was 22.7% (26.6% in the stapled group and 20.3% in the handsewn group, p = 0.30). The incidence of anastomotic leak was 6.3% in the stapled group and 7.8% in the handsewn group (p = 0.69). Multivariate analysis adjusting for blood transfusions, fecal contamination, and type of antibiotic prophylaxis showed that the adjusted odds ratio (OR) of complications in the stapled group was 0.83 (95% CI, 0.38-1.74, p = 0.63). In a second multivariate analysis adjusting for blood transfusions, hypotension, fecal contamination, Penetrating Abdominal Trauma Index, and preoperative delays the adjusted OR in the stapled group was 0.99 (95% CI, 0.46-2.11, p = 0.99). CONCLUSION The results of this study suggest that the method of anastomosis following colon resection for penetrating trauma does not affect the incidence of abdominal complications and the choice should be surgeons preference.

Prostanoids: early mediators in the secondary injury that develops after unilateral pulmonary contusion.

BACKGROUND We have previously shown a sequence of events after unilateral pulmonary contusion that suggests the release of blood-borne prostanoid mediators and that culminates in refractory bilateral pulmonary failure. PURPOSE To determine the role of platelet-derived thromboxane and endothelial-derived prostacyclin in the primary and secondary injury after unilateral blunt chest trauma, and to determine whether pretreatment with the cyclooxygenase inhibitor indomethacin alters the progression of secondary injury. METHODS Anesthetized, ventilated (FIO2 = 0.50) pigs received a unilateral, blunt injury to the right thorax (n = 20) or sham injury (n = 5) and were monitored for 24 hours. Either indomethacin (5 mg/kg i.v.; n = 10) or its saline vehicle (n = 10) were administered 15 minutes before injury. Serial bronchoalveolar lavages of each lung were analyzed for protein and neutrophil (polymorphonuclear neutrophil (PMN)) content. RESULTS Contusion caused profound hypoxemia; PaO2 partially recovered within 1 hour of injury to 50% of baseline. Thereafter, worsening hypoxemia required positive end-expiratory pressure. With indomethacin compared with vehicle, PaO2 was higher at any given level of positive end-expiratory pressure (p < 0.05). There was an early increase in serial bronchoalveolar lavage protein on the injured side (peak at 2 hours), with a delayed pulmonary capillary leak on the contralateral side (peak at 6 hours), which correlated with increasing PMN infiltration; this was reduced by 40 to 60% with indomethacin (p < 0.05). Thromboxane peaked within 1 hour after contusion at 800% baseline, then fell off rapidly. This peak preceded the maximal increase in permeability and was completely blocked by indomethacin. Prostacyclin slowly rose to 300% baseline by 3 hours and remained elevated; this change was blocked by indomethacin for 18 hours. CONCLUSIONS Contusion of the right thorax induced a delayed pulmonary capillary leak in the left lung, which reflects a progressive secondary inflammatory response. Elevations in thromboxane and prostacyclin preceded progressive bilateral PMN infiltration. Indomethacin blocked thromboxane and prostacyclin and attenuated, but did not prevent, the progression to pulmonary failure. Overall, these data suggest that prostanoids are released soon after unilateral contusion and initiate an inflammatory response in both lungs that is sustained by PMN infiltration.

Mechanism of injury does not predict acuity or level of service need: field triage criteria revisited ☆

BACKGROUND Trauma systems use specific criteria based on physiologic, anatomic, and mechanistic factors for field triage. The purpose of this study was to evaluate the emergency department disposition of patients not meeting mandatory criteria (ie, physiologic or anatomic factors) for triage to a trauma center and the potential for over- or undertriage. METHODS This was a retrospective review of trauma admissions from July 1999 to June 2001, to a level I trauma center. Triage criteria were classified as physiologic factors (n=300), anatomic factors (n=115), or mechanistic factors (n=414), according to the criteria of the American College of Surgeons Committee on Trauma. Physiologic and anatomic factors were combined and compared with mechanistic factors. RESULTS There were 1253 admissions during the study period. Sixty-six percent (n=830) met study inclusion criteria. Fifty percent (n=413) were admitted to the intensive care unit or operating room. Approximately 50% of each group (physiologic/anatomic, 52%; mechanistic, 47%; P=.08) were admitted directly to the operating room or to the intensive care unit. CONCLUSIONS Patients not meeting mandatory criteria for transfer to a trauma center often have serious injuries that require a higher level of care. The inclusion of all or select mechanistic criteria for evaluation at a trauma center is appropriate to achieve an acceptable rate of clinical undertriage, as well as resource undertriage and its subsequent complications.

Burn injury and pulmonary sepsis: development of a clinically relevant model.

BACKGROUND Despite improvements in the early resuscitation of the critically injured, mortality from multiple organ failure has remained stable, with the lung often the first organ to fail. Early intubation and mechanical ventilation predispose patients to the development of pneumonia and respiratory failure. Our objective was to establish a murine model of combined injury, consisting of burn/trauma and pulmonary sepsis with reproducible end-organ responses and mortality. METHODS Male B6D2F1 mice were divided into four groups: burn/infection (BI), burn (B), infection (I), and sham (S). Burned animals had a full-thickness 15% dorsal scald burn. BI and I groups were inoculated intratracheally with Pseudomonas aeruginosa (3-5 x 103 colony-forming units). S and B animals received saline intratracheally. All animals were resuscitated with 2 mL of intraperitoneal saline. Mortality was recorded at 24, 48, and 72 hours. Bacterial sepsis was confirmed by tissue Grams stain of the lungs and positive organ and blood cultures for Pseudomonas aeruginosa. Femoral bone marrow cells were collected at 72 hours from surviving animals. Clonogenic potential was assessed by response to macrophage (M) colony-stimulating factor (CSF) and granulocyte-macrophage (GM) CSF in a soft agar assay and the data were represented as colonies per femur. Isolated alveolar macrophages and whole lung tissue were assayed for levels of the inflammatory cytokines tumor necrosis factor-alpha and interleukin-6. RESULTS Mortality at 72 hours was 30% in BI, 12% in I, and <10% in B and S groups. Pneumonia was documented in all infected animals at 24 hours by Grams stain and positive tissue cultures for Pseudomonas aeruginosa. Systemic sepsis as confirmed by blood, and remote organ cultures was seen in BI animals only. Significantly increased responsiveness to M-CSF stimulations was noted in all groups (BI, 8,291 +/- 1,402 colonies/femur; B, 6,357 +/- 806 colonies/femur; and I, 8,054 +/- 1,112 colonies/femur; p < 0.05) relative to sham (3,369 +/- 883 colonies/femur, p < 0.05). Maximal responsiveness to GM-CSF stimulation was noted in the BI group (11,932 +/- 982 colonies/femur, p < 0.05), and similar GM responsiveness was noted in all other groups (B, 7,135 +/- 548 colonies/femur; I, 7,023 +/- 810 colonies/femur; and S, 6,829 +/- 1,439 colonies/femur). Alveolar macrophage release of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-6 increased in all animals, but the magnitude of increase was not proportional to the strength of the inciting stimulus. CONCLUSION Although minimal perturbations were seen after burn or pulmonary infection alone, the combined insult of burn and pulmonary sepsis resulted in statistically significant hematopoietic changes with increased monocytopoiesis. Only the combined injury resulted in systemic sepsis and significantly increased mortality. We have developed a clinically relevant model of trauma and pulmonary sepsis that will allow further clarification of the inflammatory response after injury and infection.

Ventilator-associated pneumonia in injured patients: Do you trust your Gram's stain?

BACKGROUND The results of sputum or bronchoalveolar lavage (BAL) fluid Grams stain have been used to guide presumptive antibiotic therapy for ventilator-associated pneumonia (VAP) in injured patients, despite reported variability in sensitivity, specificity, positive predictive value, negative predictive value, and accuracy. Our aim was to evaluate the utility of Grams stain of BAL fluid in the diagnosis of VAP. METHODS We conducted a retrospective chart review of all mechanically ventilated trauma patients who developed pneumonia over a 5-year period in whom Grams stain and final culture data were available. RESULTS One hundred fifty-five records with complete data sets were reviewed. VAP was diagnosed by Centers for Disease Control and Prevention criteria and confirmed by BAL and quantitative culture in all patients. Overall accuracy of Grams stain in diagnosing VAP for any organism was 88% (137 true-positives). When assessed for the ability to predict pneumonia caused by a specific organism, the accuracy decreased significantly, with only 63% of Gram-negative VAPs and 72% of Gram-positive VAPs accurately identified by Grams stain. However, the absence of Gram-positive organism of Grams stain excludes Gram-positive VAP in 80% of patients. CONCLUSION All trauma patients should be covered presumptively for gram-negative organisms, as they encompass 70% of infections, but are not reliably identified by Grams stain. As 88% of VAP can be identified by the presence of any organism on Grams stain, it may be useful in the early diagnosis of VAP but cannot reliably be used to guide presumptive therapy.

Endogenous adenosine and secondary injury after chest trauma.

BACKGROUND No previous studies have examined actions of adenosine or related compounds after blunt chest trauma, but we have shown that the prototype adenosine-regulating agent, acadesine (aminoimidazole carboxamide ribonucleotide [AICAR]), has multiple favorable anti-inflammatory actions after other forms of trauma, ischemia, hemorrhage, and sepsis; and that a progressive inflammatory response in the contralateral (uninjured) lung after unilateral blunt chest trauma is caused (in part) by activation and sequestration of circulating leukocytes (white blood cells [WBCs]). Thus, we hypothesized that AICAR would ameliorate WBC-dependent, secondary pathophysiologic changes after blunt chest trauma. METHODS Mongrel pigs (28+/-1 kg, n = 21) were anesthetized, mechanically ventilated, and injured on the right chest (pulmonary contusion) with a captive bolt gun. Either AICAR (1 mg/kg + 0.2 mg/kg/min) or its saline vehicle were administered for a 12-hour period, beginning 15 minutes before injury. RESULTS Injury caused a three- to fourfold increase in bronchoalveolar lavage (BAL) WBC counts, 10- to 20-fold increases in BAL protein, and 200% increases in lung edema as measured by wet-dry ratio (all p < 0.05), in both the injured (right) and the noninjured (left) lungs. With AICAR versus saline, BAL WBC counts, lung myeloperoxidase levels, and systemic hemodynamics were similar. However, the increases in BAL protein were attenuated by 30% to 50% (p < 0.14, NS) and edema was reduced (p < 0.05) in both lungs. Furthermore, oxygenation, hypercapnia, acidosis (all p < 0.05), and survival were improved (9 of 10 vs. 4 of 11, p < 0.04). CONCLUSION Pretreatment with AICAR before experimental pulmonary contusion ameliorates the trauma-induced destruction of the alveolar capillary membrane, and attenuates the delayed secondary injury in the contralateral uninjured lung, by a mechanism that may be independent of leukocytes. Endogenous adenosine could have a role in the pathophysiologic response after blunt chest injury, with potential sites of action including the endothelium and alveolar macrophage. Adenosine-regulating agents may have therapeutic potential after blunt chest injury, but further studies are needed in clinically relevant models, with administration begun at the time of resuscitation.