Vacuum-assisted complex wound closure with elastic vessel loop augmentation: a novel technique

Patients with serious abdominal or soft-tissue injuries may require multistaged surgical management. The Vacuum-Assisted Closure device, used in combination with a shoelace technique, can promote fascial and soft-tissue approximation.

Endovascular repair of a traumatic infrarenal aortic transection: a case report and review

Blunt abdominal aortic trauma occurs in up to 0.04% of all nonpenetrating traumas. Although uncommon, mortality from this injury ranges from 18% to 37%. Seat belt injury is associated with almost 50% of reported blunt abdominal aortic traumas. The authors present the case of a 21-year-old man, a restrained passenger who was involved in a high-speed motor vehicle accident. In the emergency room, he had obvious evidence of lap-belt injury. His peripheral pulses were normal and there was no pulsatile abdominal mass. Computer tomography (CT) revealed a large amount of free intraperitoneal fluid throughout with signs of mesenteric avulsion and fracture/dislocation of T11-T12. The patient underwent an exploratory laparotomy. Right hemicolectomy and resection of small bowel was performed. CT angiography revealed an aortic transection and surrounding pseudoaneurysm 2 cm above the aortic bifurcation. The patient returned to the operating room for endovascular repair. Via a right femoral cutdown, a 14 mm x 5.5 cm stent-graft was placed across the distal abdominal aorta. Follow-up arteriogram revealed complete obliteration of the pseudoaneurysm without evidence of leak. There were no complications related to the aortic stent-graft in the postoperative period. The patient was discharged in good condition. As this case demonstrates, endovascular repair of traumatic aortic injury is feasible and may represent an improved treatment in certain settings.

Trauma-specific intensive care units can be cost effective and contribute to reduced hospital length of stay

Our hypothesis was that clinical outcomes are improved and cost and hospital length of stay (LOS) reduced as a result of the opening of a closed trauma intensive care unit (ICU). We conducted a cross-sectional study in a university-affiliated Level I trauma center. Our study population comprised trauma patients admitted to the ICU between June 1, 1996 and July 1, 1998 for at least 24 hours and with an Injury Severity Score (ISS) >16 (excluding those with severe brain injury). The main outcome measures were changes in LOS and number of ventilator days, prevalence of complications, changes in patient charges, and hospital costs. Two hundred four patients were included [trauma ICU (TICU) 60, surgical ICU 144]. The two groups were not statistically different in age, ISS, mechanism of injury, infection rate, and mortality; however, the TICU patients had a lower number of ventilator hours (83.1 vs 100.0; P = 0.007), lower ICU LOS (9.4 vs 12.1 days; P = 0.06), and lower total hospital LOS (15.6 vs 22.3 days; P = 0.01). Although this was not of statistical significance TICU patients had lower hospital charges ($125,383 vs $152,994; P = 0.06) and lower cost per case ($42,306 vs $47,548; P = 0.35) for a net savings of $314,520 during the first 6 months of operation of the TICU. This study suggests that improved clinical outcomes and decreases in cost and LOS are directly related to the opening of a closed trauma ICU.

Recurrent trauma in elderly patients

HYPOTHESIS

Older patients (those aged > or = 70 years) who have experienced trauma have an increased risk of recurrent trauma. Demographic, medical, and functional factors are potential contributors to the risk of subsequent trauma among injured elderly patients.

DESIGN

Retrospective follow-up study.

PARTICIPANTS

Study participants were derived from the Longitudinal Study of Aging, an extension of the 1984 National Health Interview Survey focusing on persons who were aged 70 years and older in 1984. A cohort of elderly patients participating in the Longitudinal Study of Aging and hospitalized for injury in 1985 (n = 100) was identified using Medicare hospital discharge data. An uninjured cohort (n = 401) was also identified from the Longitudinal Study of Aging and matched for age (1 year) and sex.

MAIN OUTCOME MEASURES

Risk of admission for trauma among the injured cohort compared with the uninjured cohort and associations between demographic, medical, and functional characteristics and trauma recurrence.

RESULTS

Following adjustment for potential confounding factors, the injured cohort was 3.25 times more likely (95% confidence interval, 1.99-5.31) to be hospitalized for injury during the follow-up period compared with the uninjured cohort. Among the injured cohort, those at greatest risk of subsequent trauma included women and those with chronic medical conditions or functional impairments, the latter being the only factor independently associated with recurrence.

CONCLUSIONS

Elderly patients who have experienced trauma are at increased risk of subsequent injury. Interventions to reduce the likelihood of trauma recurrence should focus on those with chronic illnesses and functional impairments.

Long-term survival in the elderly after trauma

BACKGROUND

In the elderly, trauma has been associated with increased, long-term, all-cause mortality. Functional limitations secondary to injury may be responsible for the reduced survival rate. The objective of this study was to test this hypothesis using data from the Longitudinal Study of Aging (LSOA).

METHODS

The LSOA is an extension of the 1984 National Health Interview Survey, which focused on 7,527 persons who were 70 years and older in 1984. Using data from the LSOA, a cohort of elderly patients hospitalized for injury in 1985 (N = 102) was identified from Medicare hospital discharge data. An uninjured cohort (N = 408) was also identified using the LSOA and matched by age (within 1 year) and sex. Deaths in both cohorts were identified using the National Death Index. Hazard ratios (HRs) for mortality within 6 years subsequent to injury, adjusted for demographic, health status, and functional characteristics, were calculated.

RESULTS

The injured cohort had a significantly reduced rate of survival compared with the uninjured cohort (HR = 1.5; 95% confidence interval [CI] 1.1-2.2), and this relationship persisted after adjusting for demographic and health characteristics (HR = 1.4; 95% CI 1.0-2.0). After additional adjustment for measures of functional decline, the association diminished (HR = 1.2; 95% CI 0.8-1.7). Functional decline remained a strong, independent factor for the risk of mortality.

CONCLUSION

Trauma in the elderly has both an acute and long-term influence on mortality; the latter seems to be mediated through a decline in function resulting from the injury. This study suggests that strategies to return the elderly patient to preinjury functional status are of paramount importance. Future research should explore the impact of these interventions on long-term survival.

Reduction of vancomycin-resistant enterococcal infections by limitation of broad-spectrum cephalosporin use in a trauma and burn intensive care unit

Both vancomycin and third-generation cephalosporin use are believed to contribute to a rise in vancomycin-resistant enterococci (VRE) infections. In 1998, the largest number of VRE infections in our hospital occurred in the trauma/burn intensive care unit (TBICU), accounting for nearly 20% of hospital infections. In an attempt to control the VRE infection rate, antibiotic protocols for prophylaxis, empiric, and definitive therapy were initiated during the final quarter of 1998 to minimize cephalosporin use by the introduction of piperacillin/tazobactam. Therefore, we undertook a study of the VRE infection rate for the TBICU in relation to vancomycin, piperacillin/tazobactam, piperacillin, third-generation cephalosporin, and total cephalosporin use before and after efforts to limit cephalosporins. These data were compared to those in the medical and surgical intensive care units. During 1998, seven VRE infections occurred in the TBICU. Following initiation of antibiotic protocols, one case of VRE infection occurred in the subsequent month and no cases in the 17 months since. The decrease in the VRE infection rate corresponded with a significant increase in the use of piperacillin/tazobactam and a reduction in third-generation and total cephalosporin use. In contrast, cephalosporin use in the medical and surgical intensive care units remains significantly higher than in the TBICU, and neither unit has had a reduction in their VRE infection rates.

Prognostic factors in patients with inferior vena cava injuries

Inferior vena cava (IVC) injuries are potentially devastating insults that continue to be associated with high mortality despite advances in prehospital and in-hospital critical care. Between 1987 and 1996, 37 patients (32 males and 5 females; average age, 30 years) were identified from the trauma registry as having sustained IVC trauma. Overall mortality was 51 per cent (n = 19), with 13 intraoperative deaths and five patients dying within the first 48 hours. Blunt IVC injuries (n = 8) had a higher associated mortality than penetrating wounds (63% versus 48%). Of the 29 patients with penetrating IVC trauma, the wounding agent influenced mortality (shotgun-100% versus gunshot-43% versus stab-0%). Anatomical location of injury was also predictive of death [suprahepatic (n = 3)-100% versus retrohepatic (n = 9)-78% versus suprarenal (n = 6)-33% versus juxtarenal (n = 2)-50% versus infrarenal (n = 15)-33%]. A direct relationship existed between outcome and the number of associated injuries: nonsurvivors averaged four and survivors averaged three. Eighty per cent of patients sustaining four or more associated injuries died, by contrast to a 33 per cent mortality in those suffering less than four injuries. Physiological factors were also predictive of outcome. Patients in shock (systolic blood pressure < 80) on arrival had a higher mortality than those who were hemodynamically stable (76% versus 30%). Preoperative lactate levels were of prognostic value for death (> or = 4.0-59% versus < 4.0-0%), as was base deficit (< 4-22%, > or = 4, and < 10-36%, > or = 10-73%). Interestingly, neither time from injury to hospital arrival (47.4 minutes versus 33.0 minutes) nor time in the emergency department before surgery (45.6 minutes versus 42.6 minutes) differed between survivors and fatalities. Mortality remained high in the 34 patients who had operative control of their IVC injuries [lateral repair (n = 27)-44% versus ligation (n = 6)-66% versus Gortex graft (n = 1)-0%]. As wounding agent, anatomical location, associated injuries, and physiological status seem to most directly impact mortality, future efforts must focus both on establishing prevention programs directed at reducing the incidence of this injury, as well as on advancing the management of those who do survive to hospitalization, if we are to improve on the outcome of these devastating injuries.

Mediator-dependent secondary injury after unilateral blunt thoracic trauma

The pathophysiologic sequence leading to respiratory failure after chest trauma can be an inevitable consequence of the primary injury or a secondary, mediator-driven inflammatory process. To distinguish between these alternatives, a simple cross-transfusion experiment was performed. A captive bolt gun injured the chest of anesthetized pigs that were mechanically ventilated with FiO2 = .21, .50, or .50 plus indomethacin (5 mg/kg intravenous; 15 min before injury). Tube thoracostomy immediately followed. After 30 min, blood from these injured donors was transfused into three matched groups of naive recipients (n = 8, 6, and 4, respectively) for a 33% exchange transfusion. Two control groups received blood from uninjured donors with tube thoracostomies only (FiO2 = .21, n = 7; FiO2 = .50, n = 10). Within 15-30 min after transfusion, in recipients from injured donors versus controls, lung compliance was decreased 20%, stroke volume and cardiac output were decreased 50%, and pulmonary vascular resistance was increased >300% (all p < .05). These changes recovered to baseline within 60-90 min. The stable metabolite of thromboxane A2, thromboxane B2, increased >500% in plasma within 15 min and remained elevated for >120 min. All responses were similar at 21 % or 50% O2, which suggests that hypoxia per se is not a cause of mediator production. All responses were eliminated by indomethacin. By 24 h, histologic changes included atelectasis in 3/3 recipients from injured donors versus 0/3 recipients from uninjured donors. We conclude that 1) blunt chest trauma releases blood borne mediators, including prostanoids; 2) these mediators can cause secondary cardiopulmonary changes in naive recipients similar to those produced by chest trauma; 3) the progression to trauma-induced respiratory failure is multifactorial; 4) early pharmacologic intervention, rather than supportive care alone, may benefit some victims of severe chest trauma.

Acadesine during fluid resuscitation from shock and abdominal sepsis

OBJECTIVE

To determine properties of acadesine, the prototype adenosine regulating agent, in an experimental model in which abdominal sepsis is superimposed onto hemorrhagic shock.

DESIGN

Randomized, blinded animal study.

SETTING

University-based animal research facility.

SUBJECTS

Twenty-eight anesthetized mongrel pigs (35.5 +/- 1.1 kg).

INTERVENTIONS

The cecum was ligated and punctured to produce abdominal sepsis. To produce hemorrhagic shock, 45% to 47% of the estimated blood volume was withdrawn. After 1 hr, shed blood plus supplemental crystalloid (twice the shed blood volume) plus either acadesine (5 mg/kg bolus + 1 mg/kg x 60 min, n = 10) or its vehicle (n = 10) was administered. All animals were awakened and observed for 48 hrs. At 48 hrs, cardiac function, bacterial cultures from the septic focus, and inflammatory changes in the abdomen were quantified.

MEASUREMENTS AND MAIN RESULTS

After resuscitation with acadesine vs. vehicle, we observed the following: a) arterial blood pressure and cardiac filling pressures were similar but cardiac index, systemic oxygen delivery, and systemic oxygen consumption were increased; b) plasma lactate was higher, systemic vascular resistance was lower, but ileal mucosal blood flow was not measurably altered; c) lipopolysaccharide-evoked tumor necrosis factor production in whole blood ex vivo was reduced; d) in those animals that survived 48 hrs (10/10 vs. 8/10), sepsis-induced cardiac depression, amount of free intraperitoneal fluid, extra abscess inflammatory reaction, abscess wall formation, abscess bacterial counts, and peritoneal bacterial counts, were all similar, but blood bacterial counts were higher.

CONCLUSIONS

Fluid resuscitation with acadesine produced no adverse hemodynamic consequences and probably improved washout of metabolites from the reperfused microcirculation in sites other than the small intestine or heart. Taken together, these observations suggest that adenosine regulating agents might have therapeutic potential during fluid resuscitation from trauma. However, at least in these extreme conditions, the acute salutary effects of acadesine were probably overwhelmed by polymicrobial sepsis. Further studies must determine whether supplemental adjuvants to boost host defense during recovery from trauma will optimize adenosine-based resuscitation solutions.

Prognostic value of blood lactate, base deficit, and oxygen-derived variables in an LD50 model of penetrating trauma

OBJECTIVE

To determine whether blood lactate, base deficit, or oxygen-derived hemodynamic variables correlate with morbidity and mortality rates in a clinically-relevant LD50 model of penetrating trauma.

DESIGN

Prospective, controlled study.

SETTING

University research laboratory.

SUBJECTS

Anesthetized, mechanically-ventilated mongrel pigs (30+/-2 kg, n = 29).

INTERVENTIONS

A captive bolt gun delivered a penetrating injury to the thigh, followed immediately by a 40% to 60% hemorrhage. After 1 hr, shed blood and supplemental crystalloid were administered for resuscitation.

MEASUREMENTS AND MAIN RESULTS

After penetrating injury, 50.7+/-0.3% hemorrhage (range 50% to 52.5%), and a 1-hr shock period, seven of 14 animals died, compared with six of six animals after 55% to 60% hemorrhage, and 0 of nine animals after < or =47.5% hemorrhage. Only two of 13 deaths occurred during fluid resuscitation. At the LD50 hemorrhage, peak lactate concentration and base deficit were 11.2+/-0.8 mM and 9.3+/-1.5 mmol/L, respectively, and minimum mixed venous oxygen saturation, systemic oxygen delivery, and systemic oxygen consumption were 33+/-5%, 380+/-83 mL/min/kg, and 177+/-35 mL/min/kg, respectively. For comparison, baseline preinjury values were 1.6+/-0.1 mM, -6.7+/-0.6 mmol/L, 71+/-3%, 2189+/-198 mL/min/kg, and 628+/-102 mL/min/kg, respectively. Of all the variables, only lactate was significantly related to blood loss before and after fluid resuscitation in the 16 survivors. However, r2 values were relatively low (.20 to .50), which indicates that only a small fraction of the hyperiactacidemia was directly related to tissue hypoperfusion. In the whole population of survivors and nonsurvivors, both lactate and base deficit (but none of the oxygen-derived variables) correlated with blood loss.

CONCLUSIONS

Arterial lactate is a stronger index of blood loss after penetrating trauma than base deficit or oxygen-derived hemodynamic variables. The reliability of arterial lactate depends on several factors, such as the time after injury, the proportion of survivors and nonsurvivors in the study population, and on factors other than tissue hypoxia.

Determinants of myocardial performance after blunt chest trauma

OBJECTIVE

This study investigates whether factors that determine myocardial performance (preload, afterload, heart rate, and contractility) are altered after isolated unilateral pulmonary contusion.

METHODS

Catheters were placed in the carotid arteries, left ventricles, and pulmonary arteries of anesthetized, ventilated (FiO2=0.5) pigs (31.2+/-0.6 kg; n=26). A unilateral, blunt injury to the right chest was delivered with a captive bolt gun (n=17) followed by tube thoracostomy. To control for anesthesia and instrumentation at FiO2 of 0.5, one group received tube thoracostomy only (sham injury; n=6). To control for effects of hypoxia without chest injury, an additional sham-injury group (n=3) was ventilated with FiO2 of 0.12. To generate cardiac function (i.e., Starling) curves, lactated Ringer's solution was administered in three bolus infusions at serial time points; the slope of stroke index versus ventricular filling pressure defines cardiac contractility.

RESULTS

By 4 hours after pulmonary contusion, pulmonary vascular resistance, airway resistance, and dead space ventilation were increased, whereas PaO2 (72+/-6 mm Hg at FiO2=0.5) and dynamic compliance were decreased (all p < 0.05). Despite profound lung injury, arterial blood pressure, heart rate, cardiac filling pressures, and output remained within the normal range, which is inconsistent with direct myocardial contusion. The slope of pulmonary capillary wedge pressure versus left ventricular end-diastolic pressure (LVEDP) regression was reduced by more than 50% from baseline (p < 0.05), but there was no significant change in the slope of the central venous pressure versus LVEDP regression. By 4 hours after contusion, the slope of the stroke index versus LVEDP curve was reduced by more than 80% from baseline (p < 0.05). By the same time after sham injury with FiO2 of 0.12 (PaO2 < 50 mm Hg), the regression had decayed a similar amount, but there was no change in the slope after sham injury with FiO2 of 0.5 (PaO2 > 200 mm Hg).

CONCLUSION

After right-side pulmonary contusion, the most often used estimate of cardiac preload (pulmonary capillary wedge pressure) does not accurately estimate LVEDP, probably because of changes in the pulmonary circulation or mechanics. Central venous pressure is a better estimate of filling pressure, at least in these conditions, probably because it is not directly influenced by the pulmonary dysfunction. Also, ventricular performance can be impaired by depressed myocardial contractility and increased right ventricular afterload even with normal left ventricular afterload and preload. It is thus conceivable that occult myocardial dysfunction after pulmonary contusion could have a role in the progression to cardiorespiratory failure even without direct cardiac contusion.

Impact of stomach and colon injuries on intra-abdominal abscess and the synergistic effect of hemorrhage and associated injury

BACKGROUND

Colon wounds are recognized to be highly associated with intra-abdominal abscess (IAA) after penetrating trauma, whereas gastric wounds are thought to contribute minimally to abscess because of the bactericidal effect of low pH. This study evaluated the impact of stomach or colon wounds, the contribution of other risk factors, and associated abdominal injuries on IAA.

METHODS

Patients with penetrating colon or stomach wounds during a 10-year period were reviewed and stratified by age, Injury Severity Score, transfusions, and associated abdominal injuries. Early deaths (<48 hours) from hemorrhage were excluded. Outcomes analyzed were IAA and death.

RESULTS

A total of 812 patients were identified. There were 32 late deaths (4%), of which 28% were attributable to IAA and multiple organ failure. IAA rates for isolated stomach or colon wounds were 0 and 4.2%, respectively. The presence of associated injuries increased IAA rates to 7.5 and 8.8%, respectively. Independent predictors of IAA determined by multivariate analysis included age, transfusions, gunshot wounds, and associated injuries to the liver, pancreas, and kidney.

CONCLUSION

Gastric injuries are equivalent to colon wounds in their contribution to IAA. Contamination from either organ without associated injury is minimally associated with IAA, but injury to both appears synergistic. The immunosuppressive effects of age and hemorrhage, in addition to significant associated injury, enhance the development of IAA.

Partial liquid ventilation decreases the inflammatory response in the alveolar environment of trauma patients

BACKGROUND

Perflubron is a perfluorocarbon with unique physical characteristics. It has twice the density of water, allows free diffusion of O2 and CO2, is easily dispersed, and is insoluble. Thus, it can act as "liquid positive end-expiratory pressure" to recruit collapsed alveoli and improve oxygenation. Results of laboratory studies suggest that perflubron exerts an anti-inflammatory effect on alveolar cells. Limited clinical data in neonates and adults with severe acute respiratory distress syndrome are promising. We present a single institution's experience with partial liquid ventilation (PLV) in trauma patients compared with conventional mechanical ventilation (CMV) with particular attention to the alveolar inflammatory response.

METHODS

Ventilated patients with bilateral lung injury and PaO2/FIO2 < 300 were eligible in this prospective multicenter trial. Perflubron was administered by means of the endotracheal tube to fill up to functional residual capacity (approximately 30 mL/kg), followed by supplemental doses up to 96 hours. At this institution, bronchoscopy with bronchoalveolar lavage was performed serially for white blood cell count, protein, interleukin (IL)-1, IL-6, IL-8, and IL-10, and analyzed as early (< 48 hours) and late (48-96 hours). Clinical response was defined as a sustained 10% increase in PaO2/FIO2 at 48 hours.

RESULTS

16 patients were enrolled: 12 PLV patients and 4 CMV patients. There were no differences between groups relative to sex, Injury Severity Score, or initial PaO2/FIO2. There were no major outcome differences between groups in this pilot study relative to pneumonia (50% PLV and 75% CMV), deaths (one death in each group caused by multiple organ failure), or for oxygenation after 5 days. Eight PLV patients were responders (PLV-R) compared with four patients who did not (PLV-NR). The main differences between these subgroups was time from injury to study (1.8 days for PLV-R vs. 5.8 for PLV-NR, p < 0.02) and age (30 years for PLV-R vs. 42 years for PLV-NR, p < 0.04). Both white blood cell count and protein were higher in CMV, suggesting a greater inflammatory response. Neutrophils were significantly higher in CMV, despite equal IL-8 levels in both PLV and CMV. The inflammatory cytokines IL-1 and IL-6 were greater in CMV, and the anti-inflammatory IL-10 was lower in PLV.

CONCLUSION

Early institution of partial liquid ventilation is effective at reducing the alveolar inflammatory response. Perflubron exhibits an anti-inflammatory effect in the alveolar environment with reduction of proinflammatory IL-1 and IL-6 (possibly removing a stimulus for IL-10), white blood cell count, and protein capillary leak. PLV also reduces alveolar neutrophils independent of IL-8. Further characterization of this altered inflammatory response is necessary.

Cardiopulmonary function after pulmonary contusion and partial liquid ventilation

PURPOSE

To compare the effects of mechanical ventilation with either positive end-expiratory pressure (PEEP) or partial liquid ventilation (PLV) on cardiopulmonary function after severe pulmonary contusion.

METHODS

Mongrel pigs (32 +/- 1 kg) were anesthetized, paralyzed, and mechanically ventilated (8-10 mL/kg tidal volume; 12 breaths/min; FiO2 = 0.5). Systemic hemodynamics and pulmonary function were measured for 7 hours after a captive bolt gun delivered a blunt injury to the right chest. After 5 hours, FiO2 was increased to 1.0 and either PEEP (n = 7) in titrated increments to 25 cm H2O or PLV with perflubron (LiquiVent, 30 mL/kg, endotracheal) and no PEEP (n = 7) was administered for 2 hours. Two control groups received injury without treatment (n = 6) or no injury with PLV (n = 3). Fluids were liberalized with PEEP versus PLV (27 +/- 3 vs. 18 +/- 2 mL.kg-1.h-1) to maintain cardiac filling pressures.

RESULTS

Before treatment at 5 hours after injury, physiologic dead space fraction (30 +/- 4%), pulmonary vascular resistance (224 +/- 20% of baseline), and airway resistance (437 +/- 110% of baseline) were all increased (p < 0.05). In addition, PaO2/FiO2 had decreased to 112 +/- 18 mm Hg, compliance was depressed to 11 +/- 1 mL/cm H2O (36 +/- 3% of baseline), and shunt fraction was increased to 22 +/- 4% (all p < 0.05). Blood pressure and cardiac index remained stable relative to baseline, but stroke index and systemic oxygen delivery were depressed by 15 to 30% (both p < 0.05). After 2 hours of treatment with PEEP versus PLV, PO2/FiO2 was higher (427 +/- 20 vs. 263 +/- 37) and dead space ventilation was lower (4 +/- 3 vs. 28 +/- 7%) (both p < 0.05), whereas compliance tended to be higher (26 +/- 2 vs. 20 +/- 2) and shunt fraction tended to be lower (0 +/- 0 vs. 7 +/- 4). With PEEP versus PLV, however, cardiac index, stroke index, and systemic oxygen delivery were 30 to 60% lower (all p < 0.05). Furthermore, although contused lungs showed similar damage with either treatment, the secondary injury in the contralateral lung (as manifested by intra-alveolar hemorrhage) was more severe with PEEP than with PLV.

CONCLUSIONS

Both PEEP and PLV improved pulmonary function after severe unilateral pulmonary contusion, but negative hemodynamic and histologic changes were associated with PEEP and not with PLV. These data suggest that PLV is a promising novel ventilatory strategy for unilateral pulmonary contusion that might ameliorate secondary injury in the contralateral uninjured lung.

Prospective study of blunt aortic injury: helical CT is diagnostic and antihypertensive therapy reduces rupture

OBJECTIVE

There were two aims of this study. The first was to evaluate the application of helical computed tomography of the thorax (HCTT) for the diagnosis of blunt aortic injury (BAI). The second was to evaluate the efficacy of beta-blockers with or without nitroprusside in preventing aortic rupture.

SUMMARY BACKGROUND DATA

Aortography has been the standard for diagnosing BAI for the past 4 decades. Conventional chest CT has not proven to be of significant value. Helical CT scanning is faster and has higher resolution than conventional CT. Retrospective studies have suggested the efficacy of antihypertensives in preventing aortic rupture.

METHODS

A prospective study comparing HCTT to aortography in the diagnosis of BAI was performed. A protocol of beta-blockers with or without nitroprusside was also examined for efficacy in preventing rupture before aortic repair and in allowing delayed repair in patients with significant associated injuries.

RESULTS

Over a period of 4 years, 494 patients were studied. BAI was diagnosed in 71 patients. Sensitivity was 100% for HCTT versus 92% for aortography. Specificity was 83% for HCTT versus 99% for aortography. Accuracy was 86% for HCTT versus 97% for aortography. Positive predictive value was 50% for HCTT versus 97% for aortography. Negative predictive value was 100% for HCTT versus 97% for aortography. No patient had spontaneous rupture in this study.

CONCLUSIONS

HCTT is sensitive for diagnosing intimal injuries and pseudoaneurysms. Patients without direct HCTT evidence of BAI require no further evaluation. Aortography can be reserved for indeterminate HCTT scans. Early diagnosis with HCTT and presumptive treatment with the antihypertensive regimen eliminated in-hospital aortic rupture.

Utility of Gram's stain and efficacy of quantitative cultures for posttraumatic pneumonia: a prospective study

OBJECTIVE

This prospective trial examined the efficacy of using bronchoalveolar lavage (BAL) for the diagnosis of pneumonia (PN) and the utility of Gram's stain (GS) for dictating empiric therapy.

SUMMARY BACKGROUND DATA

Posttraumatic nosocomial PN remains a significant cause of morbidity and mortality. However, its diagnosis is elusive, especially in multiply injured patients. The systemic inflammatory response syndrome of fever, leukocytosis, and a hyperdynamic state is common in trauma patients, especially patients with pulmonary contusion. Bronchoscopy with BAL with quantitative cultures of the lavage effluent may distinguish between PN and systemic inflammatory response syndrome, and GS of the lavage effluent may guide empiric therapy before quantitative culture results.

METHODS

Mechanically ventilated trauma patients with a clinical diagnosis of PN (fever, leukocytosis, purulent sputum, and new or changing infiltrate on chest radiograph) underwent bronchoscopy with BAL. Effluent was sent for GS and quantitative cultures. The diagnostic threshold for PN was > or =10(5) colony-forming units (CFU)/mL, and antibiotics were continued. Antibiotics were stopped for < 10(5) CFU/mL and the diagnosis of systemic inflammatory response syndrome was made. Causative organisms for PN were compared to GS.

RESULTS

Over a 2-year period, 232 patients underwent 443 bronchoscopies with BAL (71% men, 29% women; mean age, 41). The mean injury severity score was 30. Sixty percent of the patients had pulmonary contusion, and 59% were cigarette smokers. The overall incidence of PN was 39% and was no different regardless of the number of BALs a patient had. The false-negative rate of BAL was 7%. GS identified gram-positive organisms in 80% of patients with gram-positive PN and 40% of patients with gram-negative PN. GS identified gram-negative organisms in 52% of patients with gram-positive PN and 77% with gram-negative PN. The duration of the intensive care unit stay relative to the timing of BAL was beneficial for guiding empiric therapy. BAL in week 1 primarily identified Haemophilus influenzae and gram-positive organisms; Acinetobacter sp. and Pseudomonas sp. were more common after week 1.

CONCLUSIONS

Bronchoscopy with BAL is an effective method to diagnose PN and avoids prolonged, unnecessary antibiotic therapy. Empiric therapy should be adjusted to the duration of the intensive care unit stay because the causative bacteria flora changes over time. GS of BAL effluent correlates poorly with quantitative cultures and is not reliable for dictating empiric therapy.

Popliteal artery trauma. Systemic anticoagulation and intraoperative thrombolysis improves limb salvage

OBJECTIVE

This study was conducted to evaluate those factors associated with popliteal artery injury that influence amputation, with emphasis placed on those that the surgeon can control.

SUMMARY BACKGROUND DATA

Generally accepted factors impacting amputation after popliteal artery injury include blunt trauma, prolonged ischemic times, musculoskeletal injuries, and venous disruption. Amputation ultimately results from microvascular thrombosis and subsequent tissue necrosis, predisposed by the paucity of collaterals around the knee.

METHODS

Patients with popliteal artery injuries over the 10-year period ending November 1995 were identified from the trauma registry. Preoperative (demographics, mechanism and severity of injury, vascular examination, ischemic times) and operative (methods of arterial repair, venous repair-ligation, anticoagulation-thrombolytic therapy, fasciotomy) variables were studied. Severity of extremity injury was quantitated by the Mangled Extremity Severity Score (MESS). Amputations were classified as primary (no attempt at vascular repair) or secondary (after vascular repair). After univariate analysis, logistic regression analysis was performed to identify the independent risk factors for limb loss.

RESULTS

One hundred two patients were identified; 88 (86%) were males and 14 (14%) were females. Forty injuries resulted from blunt and 62 from penetrating trauma. There were 25 amputations (25%; 11 primary and 14 secondary). Patients with totally ischemic extremities (no palpable or Doppler pulse) more likely were to be amputated (31% vs. 13%; p < 0.04). All requiring primary amputations had severe soft tissue injury and three had posterior tibial nerve transection; the average MESS was 7.6. Logistic regression analysis identified independent factors associated with secondary amputation: blunt injury (p = 0.06), vein injury (p = 0.06), MESS (p = 0.0001), heparin-urokinase therapy (p = 0.05). There were no complications with either heparin or urokinase.

CONCLUSIONS

Minimizing ischemia is an important factor in maximizing limb salvage. Severity of limb injury, as measured by the MESS, is highly predictive of amputation. Intraoperative use of systemic heparin or local urokinase or both was the only directly controllable factor associated with limb salvage. The authors recommend the use of these agents to maximize limb salvage in association with repair of popliteal artery injuries.

Some biomechanical considerations of polytetrafluoroethylene sutures

The biomechanical performance of polytetrafluoroethylene (PTFE) sutures has been compared with that of polypropylene sutures, the standard to which other sutures used in vascular and cardiac surgery are compared. The PTFE is supple and has no plastic memory, while the polypropylene suture is stiff and retains its plastic memory. In addition, the rate of creep encountered in the PTFE suture was significantly less than that of the polypropylene suture. The knotting profiles for knot security for either a square, granny, or surgeon's knot for polypropylene sutures were three throws each. In contrast, knot security with either a square or granny PTFE knot was accomplished with seven throws; six throws were needed for a secure surgeon's knot. The breaking strength of the unknotted and knotted PTFE sutures was approximately one half as great as that for the unknotted and knotted polypropylene sutures. Knot construction significantly reduced the breaking strength of polypropylene sutures but did not alter the breaking strength of PTFE sutures. The percent elongation experienced by both sutures before breakage did not differ significantly. The elasticity, as measured by work recovery, for the polypropylene suture was greater than that for the PTFE suture. On the basis of its unique biomechanical performance characteristics, the PTFE suture should have an important place in vascular and cardiac surgery.