Free fluid on abdominal computed tomography without solid organ injury after blunt abdominal injury does not mandate celiotomy.

BACKGROUND: Mandatory celiotomy has been proposed for all patients with unexplained free fluid on abdominal computed tomography (CT) scanning after blunt abdominal injury. This recommendation has been based upon retrospective data and concerns over the potential morbidity from the late diagnosis of blunt intestinal injury. This study examined the rate of intestinal injury in patients with free fluid on abdominal CT after blunt abdominal trauma. METHODS: This study was a multicenter prospective series of all patients with blunt abdominal trauma admitted to four level I trauma centers over 22 months. Data were collected concurrently at the time of patient enrollment and included demographics, injury severity score, findings on CT scan, and presence or absence of blunt intestinal injury. This database was specifically queried for those patients who had free fluid without solid organ injury. RESULTS: In all, 2,299 patients were evaluated. Free fluid was present in 265. Of these, 90 patients had isolated free fluid with only 7 having a blunt intestinal injury. Conversely, 91% of patients with free fluid did not. All patients with free fluid were observed for a mean of 8 days (95% confidence interval 6.1 to 10.4, range 1 to 131). There were no missed injuries. CONCLUSIONS: Free fluid on abdominal CT scan does not mandate celiotomy. Serial observation with the possible use of other adjunctive tests is recommended.

Basic aspects of and general problems in surgical infections.

Antibiotics are important in the prophylaxis and treatment of surgical infections as well as in the management of nosocomial infections acquired postoperatively in surgical patients. Surgeons encounter a range of infectious conditions, including established single-pathogen infections of soft tissues, polymicrobial intra-abdominal infections, and resistant gram-negative nosocomial infections such as ventilator-associated and aspiration pneumonia. Preoperative antibiotic administration has been shown to reduce the risk of surgical site infections and is now an accepted part of the standard care for most surgical patients. In patients with established single-pathogen or polymicrobial infections requiring surgery, studies have shown appropriate empiric antibiotic therapy to be an important adjunct to surgical intervention and general supportive measures in improving patient outcome. Antibiotics are also essential for those who develop postoperative nosocomial infections. Empiric coverage of the most likely causative organisms, especially in synergistic polymicrobial mixed infections, is one of the keys to successful prophylaxis and treatment of surgical infections.

Herpesviruses: emerging nosocomial pathogens?

BACKGROUND: Herpesviruses are ubiquitous pathogens that are known to cause infection in humans and animals. It is likely that more than 90% of adults have been infected by one or more herpesviruses. As hospitalized patients become increasingly immunosuppressed by virtue of illness or therapies, it is increasingly likely that human herpesvirus infection will become manifest in the hospital. Whether these manifestations represent manifestations of reactivated latent disease or true nosocomial infections is an open question. METHODS: Review of the pertinent English-language literature. RESULTS: There are eight known herpesviruses that cause disease in humans. Herpesviruses are double-stranded DNA viruses. The prototypical structure consists of an inner DNA core that is encased within a nucleocapsid that is icosahedral in configuration and consists of capsomere subunits. Herpesvirus infection generally occurs when virus is transmitted in oral secretions from an infected to a naive host. Clinical reactivation syndromes can occur in transplant patients, cancer chemotherapy patients, and patients with acquired immunodeficiency syndrome. Life-threatening infections are most closely associated with human herpesvirus-5 (cytomegalovirus), whereas the relationships between human herpesvirus-7 and clinical disease are largely undefined. CONCLUSION: Clinical expressions of herpesvirus in surgical patients are not nosocomial infections, but are in the vast majority of cases the reactivation of latent infection. Reactivation disease can be lethal to the immunosuppressed host.

Are antioxidant levels measured immediately postoperatively an indicator of magnitude of injury?

BACKGROUND: Little is known about the changes that occur in antioxidant levels in response to surgical trauma. The antioxidant system may influence recovery and healing after operation. Miller et al described a reliable assay for total antioxidant capacity of serum. We studied changes in antioxidant levels secondary to operation using this assay. METHODS: Twenty-seven patients were studied: 14 abdominal and 13 breast cancer operations. Initial blood samples were obtained when starting the preoperative intravenous line, the second in the recovery room, and every 6 hours thereafter. RESULTS: Levels did not correlate with diagnosis, extent of operation, age, body mass index, or complications. Differences between preoperative and postoperative values in the down and up groups were significant at P = 0.002 and P = 0.023, respectively. Differences in initial levels between the down and up groups were significant at P = 0.005. Levels 12 hours after operation were stable. CONCLUSIONS: Rapid return to a baseline of approximately 1 micromole/L, regardless of the direction of initial response, supports the concept of a set point for regulation of serum's antioxidant capacity.

Emergency department discharge of patients with a negative cranial computed tomography scan after minimal head injury.

OBJECTIVE: To determine the negative predictive value of cranial computed tomography (CT) scanning in a prospective series of patients and whether hospital admission for observation is mandatory after a negative diagnostic evaluation after minimal head injury (MHI). SUMMARY BACKGROUND DATA: Hospital admission for observation is a current standard of practice for patients who have sustained MHI, despite having undergone diagnostic studies that exclude the presence of an intracranial injury. The reasons for this practice are multifactorial and include the perceived false-negative rate of all standard diagnostic tests, the belief that admission will allow prompt diagnosis of occult injuries, and medicolegal considerations about the risk of early discharge. METHODS: In a prospective, multiinstitutional study during a 22-month period at four level I trauma centers, all patients with MHI were evaluated using the following protocol: a standardized physical and neurologic examination in the emergency department, cranial CT scanning, and then admission for observation. MHI was defined as either a documented loss of consciousness or evidence of posttraumatic amnesia and an emergency department Glasgow Coma Scale score of 14 or 15. Outcomes were measured at 20 hours and at discharge and included clinical deterioration, need for craniotomy, and death. RESULTS: Two thousand one hundred fifty-two consecutive patients fulfilled the study protocol. The CT was interpreted as negative for intracranial injury in 1,788, positive in 217, and equivocal in 119. Five patients with CT scans initially interpreted as negative required intervention. There was one craniotomy in a patient whose CT scan was initially interpreted as negative. This patient had facial fractures that required surgical intervention and elevation of depressed intracranial fracture fragments. The negative predictive power of a cranial CT scan based on the preliminary reading of the CT scan and defined by the subsequent need for neurosurgical intervention in the population fully satisfying the protocol was 99.70%. CONCLUSIONS: Patients with a cranial CT scan, obtained on a helical CT scanner, that shows no intracerebral injury and who do not have other body system injuries or a persistence of any neurologic finding can be safely discharged from the emergency department without a period of either inpatient or outpatient observation. Implementation of this practice could result in a potential decrease of more than 500,000 hospital admissions annually.

Sepsis syndrome.

A clinical syndrome including fever, leukocytosis, elevated cardiac output, and reduced systemic vascular resistance has been associated with severe infection (i.e., sepsis). However, during the last 15 years, many patients have demonstrated all of the findings that have traditionally been associated with "sepsis" but have not had demonstrated sources of infection. This led to the term "sepsis syndrome" to refer to that population of patients who appeared to have a physiologic and metabolic response associated with, but who did not have, severe infection. More commonly called the systemic inflammatory response syndrome (SIRS), the sepsis syndrome is now associated with the nonspecific systemic activation of the human inflammatory cascade by any of a number of clinical events. The management of the SIRS patient has been ineffective because of incomplete definition of the mechanisms responsible for the syndrome. It is argued that all of the biological mechanisms that are operative in a simple wound and are beneficial are negative for the host when activated systemically. Thus, SIRS is seen in three separate scenarios at present: (1) invasive infection; (2) dissemination of microbes secondary to failure of host defense mechanisms; and (3) severe activation of inflammation by injury, shock, severe soft tissue inflammation, and other noninfectious but proinflammatory events. Newer treatment strategies will need to focus not on the inciting event itself but on better control of the complex responses of the host.

Hepatitis: risks for the surgeon.

Six different hepatitis viruses have now been characterized. Hepatitis B and C are the two hepatitis infections that are of greatest concern for surgeons. Hepatitis B and C share several features that have led to this concern. Both are blood-borne infections. Both are associated with chronic infection ultimately leading to cirrhosis, portal hypertension, and hepatocellular carcinoma, and both can be occupational infections for the surgeon after percutaneous injury associated with infected blood. Chronic hepatitis B infection is seen in 1.25 million people in the U.S. It is associated with a transmission rate to healthcare workers of 25 to 30 per cent following a hollow needle stick injury. Five per cent of acute infections result in chronic disease. It can be effectively prevented as an occupational infection by vaccination with the highly effective hepatitis B vaccine. Chronic hepatitis C infection is present in nearly 4 million people in the U.S. It has a lower rate of transmission than hepatitis B following needle stick injury, but it has a 50 to 80 per cent rate of chronic disease after acute infections. There is no vaccine for hepatitis C, and only prevention of blood exposure will avoid the risks of this occupational infection. Other hepatitis viruses are likely to be identified. Prevention of blood exposure, by the better use of barriers in the operating room and modification of surgical techniques, is recommended to prevent occupational infection from both known and unknown blood-borne viruses from the surgical patient.

Multiple organ dysfunction syndrome: past, present and future.

In the past, our approach to multiple organ failure in the injured or critically ill surgical patient was driven by attempts to simplify a complex process. Early studies focused on uncontrolled invasive infection (sepsis) as the driving force of multiple organ dysfunction syndrome (MODS). However, some patients with adequately controlled infection and those without sepsis nevertheless develop MODS and signs of systemic inflammation. This discrepancy led to investigations of systemic activation of inflammation by a wider variety of biological modulators than just infection. Despite the apparent involvement of biological modulators such as endotoxin, tumor necrosis factor, and interleukin-1 receptor in MODS, agents that neutralize these modulators have failed to thwart the progression of sepsis, septic shock, and organ failure. A new paradigm suggests that, in the critically ill patient at risk for organ failure, an integrated process propagates an excessive systemic inflammatory response and/or an inadequate compensatory anti-inflammatory response. Future studies should examine the balance between these two processes at the level of the individual patient with organ failure. Careful stratification of individual patient responses to inflammatory stressors may be an essential step for creating better strategies for therapeutic interventions that can restore balance between the pro-inflammatory and anti-inflammatory processes in the critically ill patient and possibly prevent organ failure.

The consequences of suppression of anaerobic bacteria.

Anaerobic bacteria such as Bacteroides fragilis, Peptostreptococcus species, and Fusobacterium species, when accompanied by aerobic bacteria or in the presence of dead tissue, can cause severe infections. This article discusses the most common type of anaerobic infection, i.e., infection after colonic contamination of the abdominal cavity and soft tissues. Colonic anaerobes rarely cause infections as solitary pathogens. Mixed infections of aerobes and anaerobes are treated by source control, surgical drainage and debridement, and combination antibiotic therapy. Antimicrobial treatment should cover both anaerobes and aerobes; treatment of mixed infections with anti-anaerobic agents alone is likely to result in abscess formation. Recent trends toward cost cutting and the advent of antibiotics with good coverage of both aerobes and relevant pathogenic anaerobes have led to increased single-agent therapy with cefoxitin, cefotetan, ampicillin/sulbactam, imipenem/cilastatin, ticarcillin/clavulanate, trovafloxacin/alatrofloxacin, and piperacillin/tazobactam. In the past 15 years, research has begun to focus on the gut barrier, particularly on the beneficial effects of anaerobic microflora. Directing antibiotic therapy against the anaerobe when it is involved in clinical infection is important; however, the negative consequences of anti-anaerobic antibiotic therapy on the beneficial effects of normal distal gut colonization must also be considered.

The ABCs of hepatitis.

There are potentially seven hepatitis viruses in existence. Because hepatitis C and G do not fully explain the previous syndrome of non-A, non-B hepatitis, it is likely that at least one additional blood-borne hepatitis virus has yet to be identified. The consequences of the chronic hepatitis syndrome in the United States and around the world will be significant in coming decades. More patients with end-stage liver disease, portal hypertension, and hepatocellular carcinoma may be expected. The implication for surgeons is that there will be more patients with hepatitis. More importantly, the risk of hepatitis as an occupational infection will be with the current generation of surgeons for the rest of their careers. Effective hepatitis B vaccination and application of uniform practices for avoiding blood exposure and percutaneous injury become the hallmark in preventing the occupational transmission of these viruses.

Differential effects of heparin on the early and late phases of hepatic ischemia and reperfusion injury in the pig.

The mechanisms by which heparin protects the liver during induced episodes of liver ischemia-reperfusion are poorly understood. Previous work in a swine model demonstrated that serum levels of glycohydrolases and lipid peroxide peaked within 3 h after 45 minutes of hepatic ischemia followed by reperfusion. Serum levels of lactate dehydrogenase and aspartate aminotransferase peaked 20-24 h later. The aim of this study was to evaluate the effect of heparin on these two-phases of enzyme release, using a pig model of hepatic ischemia-reperfusion injury. Twenty male swine were divided into control (n = 8) and heparin (n = 12) groups. In the heparin group, heparin was administered prior to and concurrent with ischemia-reperfusion. Following 45 min of hepatic ischemia, the levels of beta-galactosidase, beta-glucosidase, acid phosphatase, purine nucleoside phosphorylase, lipid peroxides, lactate dehydrogenase, and aspartate aminotransferase in serum were monitored for up to 166 h and compared to pre-ischemic and control levels. With heparin infusion, the peak levels of beta-galactosidase, beta-glucosidase, and the lipid peroxide were reduced to 50-60% of the control levels. Acid phosphatase and purine nucleoside phosphorylase activities in serum were reduced to 25% and 60%, respectively. The peak concentrations of lactate dehydrogenase and aspartate aminotransferase were reduced to about 25% of the control level. In addition, the serum enzymes of control pigs did not return to pre-ischemic levels until 2 weeks after hepatic ischemia, while they normalized in less than 1 week in the heparin-treated animals. Systemic heparinization had different protective effects on the first and secondary phases of liver injury. These differences may reflect heparin protection of different types of liver cells. The protection of the parenchymal cells may be the combined result of reduced sinusoidal cell injury and the anticoagulant properties of heparin.

Stab wounds to the back/flank in hemodynamically stable patients: evaluation using triple-contrast computed tomography.

Triple-contrast computerized tomography (3CT) has been proposed as a method to detect high-risk injuries in hemodynamically stable patients with stab wounds (SWs) to the back/flank and to successfully triage patients with low-risk scans into a potentially cost-effective treatment algorithm. The purpose of this study was to retrospectively review our experience with the use of 3CT for diagnostic accuracy of SWs to the back/flank and to evaluate potential decreased length of stay (LOS) in the hospital for patients with low-risk scans and no associated injuries. Seventy-nine hemodynamically stable patients met criteria for inclusion in this review. Fifty-eight 3CTs were performed for initial evaluation, 44 low risk and 14 high risk, and 21 patients underwent mandatory laparotomy. The accuracy of 3CT was found to be 97.9 per cent. The LOS was significantly less in patients who had no associated injuries and a low-risk 3CT (16.5 hours), as compared with all other treatment groups. Hemodynamically stable patients with SWs to the back/flank may be safely triaged using 3CT. Patients with low-risk scans and no associated injuries may be discharged immediately, and those with potential delayed associated injuries should be observed for 6 to 24 hours. This strategy significantly decreases LOS in patients with low incidence of significant injury.

Clinical and scientific importance of source control in abdominal infections: summary of a symposium.

In May 1997, a panel of surgeon-investigators met to discuss the clinical importance and research implications of controlling the source of abdominal infections. It was concluded that source control is critical to therapeutic success and that antimicrobial therapy and other adjunctive interventions will fail if the source of infection is not controlled by resection, exteriorization or other means. The panelists presented different definitions of source control, depending on the scientific purpose of the definition. All participants agreed that failure to consider the adequacy of source control of infection has limited the value of most clinical trials of therapeutic anti-infective agents. Besides recognizing source control as an essential goal of patient care, the panelists emphasized the need for further investigative work to define, record and stratify the adequacy of source control in clinical trials of therapeutic agents for abdominal infections.

Infection in the ischemic lower extremity.

Infections in the lower extremity of the patient with ischemia can cover a broad spectrum of different diseases. An understanding of the particular pathophysiologic circumstances in the ischemic extremity can be of great value in understanding the natural history of the disease and the potential complications that may occur. Optimizing blood flow to the extremity by using revascularization techniques is important for any patient with an ischemic lower extremity complicated by infection or ulceration. Infections in the ischemic lower extremity require local débridement and systemic antibiotics. For severe infections, such as necrotizing fasciitis or the fetid foot, more extensive local débridement and even amputation may be required. Fundamentals of managing prosthetic graft infection require removing the infected prosthesis, local wound débridement, and systemic antibiotics while attempting to preserve viability of the lower extremity using autogenous graft reconstruction.

Parenteral feeding alters the fatty acid composition of serum phospholipids of rabbits.

BACKGROUND: Cholestatic liver disease develops in 30% to 70% of neonates receiving total parental nutrition (TPN). We analyzed the fatty acid composition of serum phospholipids from control and TPN-fed rabbits to determine if TPN altered the fatty acid profile. METHODS: Eleven male New Zealand White rabbits aged 9 to 11 weeks received TPN, whereas 11 other rabbits were offered standard laboratory rabbit chow ad libitum. After 14 days on the prescribed diet, serum samples were analyzed for their phospholipid fatty acid content by gas chromatography. RESULTS: The proportions of palmitolenic (16:2n7), alpha-linolenic (18:3n3), arachidic (20:0), and eicosaenoic (20:1n9) acids were significantly lower in the serum phospholipids of the TPN-fed animals compared with the control group. The proportion of docosahexaenoic acid (22:6n3), a fatty acid that is critical to the development of the nervous system, was increased two- to threefold. CONCLUSIONS: The differences in proportions of fatty acids observed between control and TPN-fed animals indicate that a fatty acid elongation and desaturation pathways are perturbed in rabbits on TPN.

Decreased polyunsaturated fatty acids in sickle cell anaemia.

The purpose of this study was to determine if the growth retardation often associated with sickle cell anaemia could be related in part to a deficiency of essential fatty acids. We reported recently that children with sickle cell disease in Jos, Nigeria have lower levels of serum amino acids and higher levels of urinary amino acids than their healthy counterparts. In the current study, we determined that the serum phospholipids of children with sickle cell anaemia did not deviate in the proportions of the essential fatty acids, linoleic and alpha-linolenic they contain compared to controls. However, their serum phospholipid profiles were significantly different in the proportions of four other fatty acids. Specifically, the phospholipids of children with sickle cell anaemia contained 19 per cent more palmitic acid (P = 0.006), 22 per cent more oleic acid (P = 0.014), 18 per cent less arachidonic acid (P = 0.008), 51 per cent less eicosapentaenoic acid (P = 0.0008), and 43 per cent less decosahexaenoic acid (P = 0.001). These data show that children with sickle cell anaemia are not deficient in essential fatty acids, but that the fatty acid elongation and desaturation pathway is somehow disturbed in this disease.

Admission or observation is not necessary after a negative abdominal computed tomographic scan in patients with suspected blunt abdominal trauma: results of a prospective, multi-institutional trial.

OBJECTIVES: Hospitalization for observation is the current standard of practice for patients who have sustained blunt abdominal trauma and who do not require emergent operation, despite having undergone diagnostic studies that exclude the presence of an intra-abdominal injury. The reasons for this practice are multifactorial and include the perceived false-negative rate of all standard diagnostic tests, the belief that hospitalization will allow for the prompt diagnosis of occult injuries, and medicolegal considerations about the risk of early discharge. The focus of this study was to determine whether hospitalization for observation is necessary after a negative diagnostic evaluation after blunt abdominal trauma, to determine the negative predictive value of abdominal computed tomographic (CT) scanning in a prospective series of patients, and to identify which patients can be safely released from the emergency department without observation or hospitalization after blunt abdominal trauma. METHODS: In a prospective, multi-institutional study over 22 months at four Level I trauma centers, all patients with blunt abdominal trauma suspected by either physical examination or mechanism of injury were evaluated using the following protocol: physical examination in the emergency department, followed by abdominal CT scanning, followed by hospitalization for observation. The standardized physical examination was repeated between 4 and 8 hours. Outcomes were measured at 20 hours and at discharge and included clinical deterioration, the need for celiotomy, and mortality. Other data collected included demographics, mechanism of injury, and findings on physical examination and abdominal CT scanning. RESULTS: Three thousand eight hundred twenty-two consecutive patients with suspected abdominal trauma presented to the four trauma centers. Two thousand seven hundred seventy-four of these met study eligibility criteria and were prospectively enrolled. Of these, 2299 fulfilled the entire study protocol. CT scan was negative in 1,809 patients, positive for organ injury or abdominal fluid in 389 patients, and nondiagnostic in 78 patients. Abdominal tenderness or bruising was present in 1,380 patients (61%), but only 22% had a positive CT scan. Nineteen percent of patients with a positive CT scan had no tenderness. Computed tomography detected 22 of the 25 blunt intestinal injuries in this series. Free intraperitoneal fluid without solid visceral injury was present in 90 patients, and but only 7 patients had intestinal injuries. There were nine celiotomies in patients whose CT scan was initially interpreted as negative: six were therapeutic (intestine in three, bladder in one, kidney in one, and diaphragm in one), two were nontherapeutic, and one was negative. The negative predictive power of an abdominal CT scan based on the preliminary reading and as defined by the subsequent need for a celiotomy in the population fully satisfying the protocol was 99.63% (lower 95 and 99% confidence bounds of 99.31 and 99.16%, respectively). CONCLUSION: These data indicate that abdominal tenderness is not predictive of an abdominal injury and that patients with a negative CT scan after suspected blunt abdominal trauma do not benefit from hospital admission and prolonged observation.