Investigations on the role of the salmon louse, Lepeophtheirus salmonis (Caligidae), as a vector in the transmission of Aeromonas salmonicida subsp. salmonicida.

A bacteria-parasite challenge model was used to study the role of sea lice, Lepeophtheirus salmonis (Copepoda), as a vector of Aeromonas salmonicida subsp. salmonicida. Three hypotheses were tested: (i) L. salmonis can acquire A. salmonicida subsp. salmonicida via water bath exposure; (ii) L. salmonis can acquire the bacteria via parasitizing infected Atlantic salmon, Salmo salar; and (iii) L. salmonis can transmit the bacteria to naïve Atlantic salmon via parasitism. Adult L. salmonis exposed to varying A. salmonicida subsp. salmonicida suspensions (10(1) -10(7)  cells mL(-1) ) for 1.0, 3.0 or 6.0 h acquired the bacteria externally (12.5-100%) and internally (10.0-100%), with higher prevalences associated with the highest concentrations and exposures. After exposure to 10(7)  cells mL(-1) , viable A. salmonicida subsp. salmonicida could be isolated from the external carapace of L. salmonis for 120 h. Lepeophtheirus salmonis also acquired the bacteria externally and internally from parasitizing infected fish. Bacterial transmission was observed only when L. salmonis had acquired the pathogen internally via feeding on 'donor fish' and then by parasitizing smaller (<50 g) 'naive' fish. Under specific experimental conditions, L. salmonis can transfer A. salmonicida subsp. salmonicida via parasitism; however, its role as a mechanical or biological vector was not defined.

Modulation of cellular innate immunity by Lepeophtheirus salmonis secretory products.

Lepeophtheirus salmonis produces pharmacologically active substances that have been shown to modify genetic expression of inflammatory mediators in SHK-1 cells and head kidney macrophages of salmon. Differences in genetic expression among genera of Oncorhynchus and Salmo reflect different susceptibilities to L. salmonis. This study was conducted to determine if the presence of L. salmonis secretory products (SEPs)(1) alters the cellular innate immune response (specifically macrophage function) among several salmonids. Phagocytic assays were performed using SHK-1 cells and macrophages isolated from pink (Oncorhynchus gorbuscha), chum (Oncorhynchus keta) and Atlantic (Salmo salar) salmon following incubation with SEPs and Aeromonas salmonicida. Respiratory burst assays were analyzed using pink, chum and Atlantic salmon macrophages after exposure to SEPs. For SHK-1 cells, incubation with SEPS led to dose-dependent increases in phagocytosis. Following incubation with SEPs, chum salmon macrophages had the highest phagocytic index (55.1%) followed by Atlantic (26.4%) and pink (15.8%) salmon. In contrast, respiratory burst response was greatest in pink salmon and minimal in the other two species. Our results suggest that the cellular innate immune response of salmon is modified in the presence of L. salmonis secretions and differences observed among species provide insight into species-specific consequences of sea lice infection.

Vector potential of the salmon louse Lepeophtheirus salmonis in the transmission of infectious haematopoietic necrosis virus (IHNV).

To better understand the role of vector transmission of aquatic viruses, we established an in vivo virus-parasite challenge specifically to address (1) whether Lepeophtheirus salmonis can acquire infectious haematopoietic necrosis virus (IHNV) after water bath exposure or via parasitizing infected Atlantic salmon Salmo salar and if so, define the duration of this association and (2) whether L. salmonis can transmit IHNV to naive Atlantic salmon and whether this transmission requires attachment to the host. Salmon lice which were water bath-exposed to 1 x 10(5) plaque-forming units (pfu) ml(-1) of IHNV for 1 h acquired the virus (2.1 x 10(4) pfu g(-1)) and remained IHNV-positive for 24 h post exposure. After parasitizing IHNV-infected hosts (viral titer in fish mucus 3.3 x 10(4) pfu ml(-1)) salmon lice acquired IHNV (3.4 x 10(3) pfu g(-1)) and remained virus-positive for 12 h. IHNV-positive salmon lice generated through water bath exposure or after parasitizing infected Atlantic salmon successfully transmitted IHNV, resulting in 76.5 and 86.6% of the exposed Atlantic salmon testing positive for IHNV, respectively. In a second experiment, only salmon lice that became IHNV-positive through water bath exposure transmitted IHNV to 20% of the naive fish, and no virus was transmitted when IHNV-infected salmon lice were cohabitated but restrained from attaching to naive fish. Under laboratory conditions, adult L. salmonis can acquire IHNV and transmit it to naive Atlantic salmon through parasitism. However, the ephemeral association of IHNV with L. salmonis indicates that the salmon louse act as a mechanical rather than a biological vector or reservoir.

Maximizing tolerance of enteral nutrition in severely injured trauma patients: a comparison of enteral feedings by means of percutaneous endoscopic gastrostomy versus percutaneous endoscopic gastrojejunostomy.

BACKGROUND: Intolerance of enteral nutrition interrupts caloric balance and increases hospital costs. This study proposes that enteral feeding by percutaneous endoscopic gastrojejunostomy (PEGJ) provides continuous uninterrupted nutrition with greater consistency than percutaneous endoscopic gastrostomy (PEG). METHODS: This prospective nonrandomly assigned study was conducted at a Level I trauma center from December of 1997 through October of 1998. All feeding tubes were placed by trauma/critical care surgeons for nutritional support. Feeding course was monitored for 14 days from time of tube placement. Demographic data and outcome variables compared were age, sex, Injury Severity Score, Abbreviated Injury Score, hospital length of stay, number of days to reach nutritional goal feedings, caloric goal, protein goal, cc/hr at goal, total parenteral nutrition usage, complications, and hospital charges. Statistical analyses used the independent samples t test, Cox regression, and Pearson chi2 with significance level set at 0.05. RESULTS: Patients receiving enteral nutrition by PEGJ reached nutritional goal sooner than patients who received enteral nutrition by PEG (p = 0.02). Thirty-seven of 46 PEGJ patients (80%) were at goal rate at day 3, whereas 28 of 43 PEG patients (65%) were at goal on day 3. Nine of 43 PEG patients (21%) and 3 of 46 PEGJ patients (7%) failed to reach goal within 14 days. CONCLUSION: This study suggests that enteral nutrition delivered by means of PEGJ is better tolerated than enteral nutrition delivered by means of PEG in trauma patients with no abdominal conditions that preclude percutaneous feeding tube placement.

Vacuum pack technique of temporary abdominal closure: a 7-year experience with 112 patients.

BACKGROUND: Temporary abdominal wound closure after celiotomy for trauma is often desirable. The ideal method of temporary closure should allow rapid closure, easy maintenance, and allow reexploration and wound repair with minimal tissue damage. Over the past 7 years, we have successfully used a vacuum closure system (the vacuum pack) for temporary management of the open abdomen. METHODS: Medical records of trauma patients undergoing exploratory celiotomy from April of 1992 to February of 1999 were reviewed. Demographic data as well as indications for open-abdominal management and complications of open-abdominal management were collected. RESULTS: Two hundred sixteen vacuum packs were performed in 112 trauma patients. Of the 216 vacuum packs placed, 2.8% were placed for increased intra-abdominal pressure, 5.3% for inability to achieve tension-free fascial closure, 20% for damage control, 55% for reexploration, and 16.7% for a combination of factors. Sixty-two patients (55.4%) went on to primary closure and 25 patients (22.3%) underwent polyglactin mesh repair of the defect followed by wound granulation and eventual skin grafting. Twenty-two patients (19.6%) died before abdominal closure was attempted. Five patients (4.5%) developed enterocutaneous fistulae. Five patients (4.5%) developed intra-abdominal abscesses. There were no eviscerations. Three patients (2.7%) required further explorations after abdominal closure. Overall mortality rate was 25.9%, none related to the vacuum pack. CONCLUSIONS: The vacuum pack is the temporary abdominal wound closure of choice in patients undergoing open abdominal management at our institution. Primary closure is achieved in the majority of patients with a low rate of complication. The technique is simple and easily mastered. Technical complications are rare and easily repaired.

Prehospital blood transfusion versus crystalloid alone in the air medical transport of trauma patients.

INTRODUCTION: Differences in prehospital resuscitation measures and outcomes of trauma patients transported by two air medical programs were assessed comparing the prehospital administration of crystalloid only (Group A) with the administration of 2 liters of crystalloid followed by blood (Group B). METHODS: A 1-year retrospective review of flight and hospital records of patients taken to Level I trauma centers by two separate air medical programs was completed. Physiologic variables, total fluids infused, and flight times were compared. RESULTS: Thirty-one patients (Group A) received crystalloids in flight, and 17 patients received in-flight blood (Group B). No statistical differences were found between the two groups when comparing age, ISS, PS, RTS, GCS, survival, and total fluid volume. Group B had statistically greater mean flight times compared with Group A (P < .05). A difference was demonstrated between groups A and B in pH and HCO3 measurements (P < .05), with Group B presenting in a more acidotic state on admission to the hospital. CONCLUSION: Patients with lengthy flight times, despite the administration of blood products, presented to the trauma center more acidotic than trauma patients receiving only crystalloid. The true impact of blood products on outcome could not be demonstrated because of statistical differences in flight times between the groups. A multicenter study matching flight times, head injury status, and flight type of assess benefit of prehospital utilization of blood products is warranted.

Posttraumatic carotid cavernous fistula: frequency analysis of signs, symptoms, and disability outcomes after angiographic embolization.

OBJECTIVE: To increase awareness and understanding of posttraumatic carotid cavernous fistula (PTCCF) with the intent to expedite diagnosis and treatment of this disabling injury, a 14-year retrospective review of patients with angiographically identified PTCCF was conducted at this Level I trauma center. A frequency analysis of signs, symptoms, and disability was performed. The impact on disability of demographics, number of embolization attempts required for closure of the PTCCF, and time from injury to diagnosis was assessed by t test for independent samples. RESULTS: Nine patients were diagnosed with 10 PTCCFs. Mean patient age was 41.5 years. All patients with PTCCF had basilar skull fracture, loss of consciousness, bruit, and chemosis; 90% had exophthalmos; 70% had visual changes; 50% complained of headache; and 80% had some lasting disability. Mean age of patients with partial to total disability was 47 years, while the mean age of patients without lasting disability was 19.5 years (p = 0.013). No statistical correlation could be found between disability and sex, blunt versus penetrating injury, days to diagnosis, or number of embolization attempts. CONCLUSION: Patients sustaining head trauma with basilar skull fractures and presenting with the described signs and symptoms should be evaluated for PTCCF. Risk of disability does not appear to be influenced by number of attempts at embolization or time to diagnosis. However, age may have a significant impact on outcome.

Internal fixation of the sternum in median sternotomy dehiscence.

Sternal dehiscence may be defined as separation of the bony sternum and manubrium following median sternotomy. It may occur at any time postoperatively and has various etiologies. Restoration of sternal integrity in sternal dehiscence is a challenging problem, particularly when associated with deep-seated infection. This report reviews a single-stage technique that virtually eliminates the infected sternotomy wound and provides anatomic reduction and stabilization of the sternum. Complete debridement of infected and/or nonviable soft tissue, bone, and cartilage is followed by pulse irrigation. Parallel stainless steel mandibular reconstruction plates are then placed on each side of the remaining sternum and wired together. One or more transmanubrial compression plates may be added. Bilateral pectoralis major musculocutaneous flap advancement and primary skin closure is performed over two to three closed suction drains. From January of 1994 to July of 1996, this technique was used by the same surgeon in 26 male and 4 female patients aged 43 to 78 years (mean = 61). Indications for the operation were sternal dehiscence with infection (osteomyelitis and/or mediastinitis) in 14 patients and sternal dehiscence without infection in 16 patients. All patients survived to discharge with mean time on the ventilator, intensive care unit length of stay, and postoperative length of stay of 0.7, 2, and 8 days, respectively. Choice and duration of antibiotics were based on culture results and operative findings. Subsequent hardware removal was necessary in one patient for hardware loosening and three patients for late periplate infection. A closed wound was eventually achieved in all 30 patients, and sternal stability was restored in 29 patients. In the management of sternal dehiscence, the described technique of internal fixation can provide anatomic sternal reduction and stabilization, elimination of infection, and wound closure in a single-stage operation. Successful outcomes were achieved despite the presence of severe infection.

Mediastinal evaluation utilizing the reverse Trendelenburg radiograph.

When thoracic aortic rupture is suspected, a 45-degree reverse Trendelenburg (RT) anteroposterior (AP) chest radiograph should place the mediastinal structures in a more appropriate position and allow a more accurate evaluation than a supine AP radiograph. One hundred ninety-one consecutive hemodynamically stable adult patients with major blunt thoracic trauma were initially evaluated for mediastinal abnormalities associated with aortic disruption by both supine AP chest radiograph and an AP chest radiograph with the patient in 45-degree RT position. One hundred four patients underwent contrast aortography based on mediastinal abnormalities detected on the supine AP chest radiograph. Twenty of these patients had abnormal aortograms demonstrating traumatic aortic disruption confirmed at surgery. Supine and RT chest radiographs were retrospectively compared in a blinded fashion to evaluate their specificity and positive predictive value for detection of traumatic thoracic aortic rupture. If RT chest radiographic findings had been used to determine the need for further assessment, 29 angiograms (26%) would have been eliminated, specificity would have increased from 52 per cent to 69 per cent, and positive predictive value would have increased from 19 per cent to 27 per cent. Both supine and RT chest radiographs demonstrated mediastinal widening in all 20 patients with abnormal aortograms, with no missed thoracic aortic disruptions (100% sensitivity). This study indicated that the RT chest radiograph may be used instead of the standard supine radiograph as the initial screen for mediastinal evaluation, maintaining a high sensitivity and eliminating the cost and morbidity of many unnecessary aortograms.

Sledding injuries in the southeastern United States.

BACKGROUND: Heavy ice and snow accumulation combined with record low temperatures in Chattanooga, Tennessee, from February 2-6, 1996, contributed to many sledding injuries. METHODS: We retrospectively reviewed medical records of emergency visits to seven area hospitals from February 2-6, 1996. We further reviewed sledding injury records. Sledding was defined as sliding on snow or ice using any device except skis. RESULTS: Of 2,134 emergency room visits, 241 patients had 310 sledding injuries. Ages of patients ranged from 3 to 53 years (mean, 18.9; median, 16). One hundred twenty-eight injuries were severe. These included extremity injuries (65), head injuries (28), chest injuries (10), intra-abdominal injuries (10), vertebral column fractures (11), and pelvic fractures (4). Thirty-six patients required inpatient hospitalization; 18 had surgery. The minimum healthcare costs associated with these injuries were estimated at $220,000. CONCLUSIONS: Major trauma potential is associated with sledding, especially where significant winter storms are uncommon. Level I trauma centers should seasonally incorporate sledding safety into community-wide injury prevention programs.

Vacuum pack technique of temporary abdominal closure: a four-year experience.

The purpose of this review is to present a 4-year experience with the vacuum pack technique of temporary abdominal closure. From April 1992 to December 1996, 171 vacuum packs were performed on 93 patients. Eighty-seven vacuum packs were performed on 38 general surgical patients, and 84 vacuum packs were performed on 55 trauma patients. Overall hospital mortality was 32 per cent. Methods of achieving permanent wound closure varied in 73 patients. Four patients (4.3%) developed enterocutaneous fistulae; four patients developed intra-abdominal abscesses (4.3%). There were no eviscerations. Management of the complicated intra-abdominal process is discussed: 1) the decision to manage the abdomen in an open fashion; 2) which method of temporary closure to use; 3) subsequent explorations; 4) when the abdomen should be closed; 5) which type of closure to use; and 6) when the abdominal wall should be revised (herniorrhaphy). The vacuum pack is the method of choice for open abdomen management and temporary abdominal closure at our institution. With careful subsequent management, good patient outcome can be achieved.

Traumatic abdominal aortic pseudoaneurysm causing biliary obstruction: a case report and review of the literature.

A traumatic pseudoaneurysm of the suprarenal abdominal aorta was diagnosed in a 58-year-old man 32 years after he received a gunshot wound to the abdomen. Epigastric pain and obstructive jaundice were the presenting symptoms. Repair was performed by intraluminal polytetrafluoroethylene patch aortoplasty with resolution of the biliary obstruction. The literature on traumatic abdominal aortic pseudoaneurysm is reviewed and reveals that this report is the first to describe biliary obstruction caused by such a lesion.

The role of ultrasonography and inferior vena cava filter placement in high-risk trauma patients.

Undetected lower-extremity deep-vein thrombosis (LEDVT) in the trauma patient can lead to significant morbidity and mortality. The purpose of this study was to: 1) evaluate the role of ultrasonography in the early detection of LEDVT in high-risk trauma patients; 2) identify prognostic indicators that predict LEDVT; and 3) evaluate the efficacy of selected inferior vena cava (IVC) filter placement in the prevention of pulmonary emboli. From October 1993 through December 1994, all adult multiple-trauma patients admitted to the Trauma Service who required prolonged bed rest (>3 days) or sustained a lower-extremity, pelvic, or spinal fracture with paralysis were prospectively studied with serial physical examinations and lower-extremity venous ultrasounds within 72 hours of admission and then weekly until discharge. Two hundred twenty-eight patients were entered into the study. Thirty-nine patients (17%) developed ultrasound evidence of LEDVT; of these, only seven (18%) were evident on physical examination. This allowed 32 patients (82%) with unsuspected LEDVT to receive earlier definitive therapy. Multivariate logistic regression analysis of LEDVT with various predictors found age, hospital length of stay, and lower-extremity trauma to be significant predictors of LEDVT (P < 0.05). Twenty-nine patients (74%) had immediate IVC filter placement upon ultrasound identification of proximal LEDVT. None of these patients developed pulmonary emboli. Ten patients (26%) with a LEDVT were treated with systemic anticoagulation alone. One of these patients sustained a fatal pulmonary embolus. In a historic control group of 234 high-risk trauma patients admitted in the 14 months prior to implementing screening ultrasounds, six patients sustained pulmonary emboli (P < 0.05). Screening ultrasounds combined with selective placement of IVC filters play an important role in reducing the morbidity and mortality associated with LEDVT in high-risk trauma patients.

Autotransfusion utilization in abdominal trauma.

The purpose of this review is to investigate the utility of autotransfusion in trauma patients in the past 3 years. A retrospective review was conducted of the charts for whom the Haemonetics Cell Saver autotransfusion device (Haemonetics Corp., Natick, MA) was utilized between January 1, 1993, and December 31, 1995. The estimated blood loss and quantity of blood transfused were noted for abdominal trauma patients. Costs of autotransfusion were then compared to estimated blood bank costs for this group. The Haemonetics Cell Saver autotransfusion device was requested for 592 cases from January 1, 1993, to December 31, 1995. Nonorthopedic trauma cases comprised 25 per cent of all autotransfusion cases. One hundred twenty-six patients had isolated abdominal trauma and had a mean estimated blood loss of 4864 +/- 6070 cc. The average volume of intraoperatively salvaged autologous blood transfused (autotransfusion) per patient was 1547 +/- 2359 cc, or a bank blood equivalent of 6.9 units of packed red blood cells. The total cost of autotransfusion in these patients was $63,252.00. Had bank blood been used instead of salvaged autologous blood, the cost would have been $114,523.00; thus, autotransfusion resulted in a savings of $51,271.00. The use of salvaged autologous blood comprised 45 per cent of total blood transfused. On a case-by-case basis, 75 per cent of cases were cost-effective compared to blood bank costs for an equivalent transfusion. Transfusion of intraoperatively salvaged autologous blood (autotransfusion) is a cost-effective, efficient way to provide blood products to operative trauma patients.

Serum amylase and lipase in the evaluation of acute abdominal pain.

The purpose of this study was to determine 1) the incidence and magnitude of elevation in admission serum amylase and lipase levels in extrapancreatic etiologies of acute abdominal pain, and 2) the test most closely associated with the diagnosis of acute pancreatitis. Serum amylase and lipase levels were obtained in 306 patients admitted for evaluation of acute abdominal pain. Patients were categorized by anatomic location of identified pathology. Logistic regression analysis was used to compare the enzyme levels between patient groups and to determine the correlation between elevation in serum amylase and lipase. Twenty-seven (13%) of 208 patients with an extrapancreatic etiology of acute abdominal pain demonstrated an elevated admission serum amylase level with a maximum value of 385 units (U)/L (normal range 30-110 U/L). Twenty-six (12.5%) of these 208 patients had an elevated admission serum lipase value with a maximum of 3685 U/L (normal range 5-208 U/L). Of 48 patients with abdominal pain resulting from acute pancreatitis, admission serum amylase ranged from 30 to 7680 U/L and lipase ranged from 5 to 90,654 U/L. Both serum amylase and lipase elevations were positively associated with a correct diagnosis of acute pancreatitis (P < 0.001) with diagnostic efficiencies of 91 and 94 per cent, respectively. A close correlation between elevation of admission serum amylase and lipase was observed (r = 0.87) in both extrapancreatic and pancreatic disease processes. Serum amylase and lipase levels may be elevated in nonpancreatic disease processes of the abdomen. Significant elevations (greater than three times upper limit of normal) in either enzyme are uncommon in these disorders. The strong correlation between elevations in the two serum enzymes in both pancreatic and extrapancreatic etiologies of abdominal pain makes them redundant measures. Serum lipase is a better test than serum amylase either to exclude or to support a diagnosis of acute pancreatitis.

On the distribution and abundance of eel parasites in Nova Scotia: local versus regional patterns.

Site-to-site variation in macroparasite species distribution and richness was observed in eels (Anguilla rostrata) among 7 sites in the Timber Lake drainage system, Nova Scotia. There was a positive relationship between maximum local species distribution, as measured by maximum prevalence at a site, and regional distribution, as measured by the number of sites in which a parasite was found within the watershed and among 28 sites across Nova Scotia. Species richness increased with spatial scale. However, the species richness of host-specific parasites approached a maximum at the spatial scale of the watershed, whereas that of generalist parasites continued to increase with increasing scale. The near-peak in species richness of eel specialists at the watershed level suggests that in a functional sense for these parasites it is the spatial scale of the watershed that serves as a species pool from which local species richness is derived.

A novel herpes simplex virus 1 gene, UL43.5, maps antisense to the UL43 gene and encodes a protein which colocalizes in nuclear structures with capsid proteins.

An open reading frame mapping antisense to the UL43 gene of herpes simplex virus 1 encodes a protein with an apparent Mr of 38,000. The protein was detected in wild-type-infected cells with rabbit monospecific polyclonal antibody directed against a fusion protein containing all of the sequences encoded by the open reading frame. The antibody did not react with mutants from which the open reading frame was deleted. Expression of this gene, designated UL43.5, was grossly decreased or abolished in infected cells incubated in medium containing inhibitory concentrations of phosphonoacetic acid, suggesting that it is regulated as a gamma gene. UL43.5 is dispensable in cell culture. UL43.5 protein colocalized with the major capsid protein (infected cell protein 5) and the capsid scaffolding proteins (infected cell protein 35) in nuclear structures situated at the periphery of the nucleus. The predicted amino acid sequence indicates that the UL43.5 protein is a highly hydrophilic protein. The colocalization of UL43.5 protein with capsid proteins in discrete nuclear structures suggests that the former may be involved in assembly of viral particles in an accessory role in cells in culture.