Risk of infection after penetrating abdominal trauma

Laparoscopic treatment of a sigmoid perforation after colonoscopy. Case report and review of literature

The authors report a case of sigmoid colon perforation post colonoscopic polypectomy. Such perforation is rare and has been estimated to occur between 0.1 and 3% of the time. Surgical treatment is necessary when there is deterioration of the clinical state. In this reported case, surgical closure of the perforation was achieved by laparoscopy. We believe that this approach is effective for colonic suture, peritoneal lavage, and drainage.

Multiple organ injuries and failures caused by shock and reperfusion after gunshot wounds

Experiments were performed to observe the changes of multiple system organ failure (MSOF) and gut barrier function caused by shock and reperfusion after gunshot wounds. Eighteen dogs were divided randomly into two groups. In the experimental group, the dogs were subjected to 60 minutes of shock (40mm Hg), followed by reinfusion of shed blood after hindlimb gunshot wounds. In the control group, the dogs experienced pure gunshot wounds without shock and reperfusion. The results showed that dogs in the experimental group developed multiple system organ injuries or failures compared with the control group. The levels of malondialdehyde (MDA) values in plasma were significantly elevated in the experimental group when compared with preinjury and the control group. Gut flora disorder, bacillus intestinalis overgrowth, and bacterial translocation occurred in the experimental group. The pathological results support the gut barrier function injury. The results indicated that pure gunshot wounds do not easily injure gut barrier function and produce MSOF. Gunshot wounds with shock and reperfusion are capable of causing gut flora disorder, bacillus intestinalis overgrowth, and lead to bacterial translocation, furthermore causing MSOF. Although fluid resuscitation is a potential treatment modality, pathogenically, it can lead to MSOF.

Effect of halothane on phenylephrine-induced vascular smooth muscle contractions in endotoxin-exposed rat aortic rings

OBJECTIVES

a) To determine the response of endotoxin-exposed vascular smooth muscle to exogenous vasoconstrictors during concomitant exposure to an inhaled anesthetic (halothane); and b) to determine if excess nitric oxide production is responsible for any altered response.

DESIGN

In vitro, prospective, repeated-measures, dose-response study.

SETTING

University/medical school experimental physiology laboratory.

SUBJECTS

Adult male Sprague-Dawley rats, whose aortae were studied in an in vitro preparation.

INTERVENTIONS

Thoracic aortae were excised from anesthetized animals and cut into 3-mm rings. After incubation in aerated organ baths containing a modified essential medium with or without Escherichia coli lipopolysaccharide (100 micrograms/mL) at 37 degrees C for 5 hrs, the rings were removed and suspended in separate baths for isometric tension recording. Phenylephrine dose-response data (10(-10) to 10(-5) M) were determined for lipopolysaccharide- and nonlipopolysaccharide-treated rings. After washout and equilibration, two vessels (one each lipopolysaccharide- and nonlipopolysaccharide-treated) were additionally exposed to 2% halothane and phenylephrine dose-response determinations were repeated for all vessels. This procedure was repeated for 1% halothane in a separate experiment. In some experiments, the nitric oxide synthase inhibitor, N omega-nitro-L-arginine (3 x 10(-4) M), was added to the bath after the washout from the second phenylephrine dose-response determination. Then, a third phenylephrine dose-response determination was performed, with and without 2% halothane.

MEASUREMENTS AND MAIN RESULTS

Dose-response curves were evaluated using a logistic regression analysis. In addition, absolute and percentage changes in tension were compared between the first and second contractions. Exposure to lipopolysaccharide resulted in a decrease in the maximum tension from 2.07 +/- 0.03 (controls) to 1.24 +/- 0.04 g/mg of vessel dry weight and an increase in the dose at which the contraction is 50% of maximum (ED50) from 3.78 x 10(-8) to 2.05 x 10(-7) M (p < .05). Exposure to 2% halothane produced significant reductions in the maximum tensions in both groups. The lipopolysaccharide-treated vessels showed not only a proportionately larger decrease (-51 +/- 5% vs. -18 +/- 2% in the control plus halothane group), but also a significantly greater absolute decrease (0.59 +/- 0.09 vs. 0.34 +/- 0.04 g/mg in the control plus halothane group). The addition of 1% halothane produced less pronounced decreases in tension, with only an additive effect in the lipopolysaccharide-treated vessels. The addition of N omega-nitro-L-arginine resulted in a reversal of the lipopolysaccharide-induced decrease in tension. However, 2% halothane still had a significantly greater effect on the lipopolysaccharide-exposed rings.

CONCLUSIONS

Exposure of rat aortic rings to lipopolysaccharide in vitro decreased the contractile response to phenylephrine. The addition of 2% halothane resulted in a more than additive decrease in tension in the lipopolysaccharide-treated vessels. Patients in septic or endotoxic shock are sensitive to most anesthetic regimens, and some of this sensitivity may be due to an altered vasoconstrictive response induced by lipopolysaccharide exposure. The inability of nitric oxide synthase inhibition to reverse this response completely suggests that induction of nitric oxide synthase and increased production of nitric oxide are not solely responsible for this finding.

Factors related to the occurrence of postoperative complications following penetrating gastric injuries

The aim of this study was to determine the relationship between diaphragmatic injury and gross contamination of the peritoneal cavity caused by gastric injuries and the occurrence of postoperative complications, especially those related to the pleural cavity. Charts of 73 patients sustaining gastric injuries due to penetrating trauma were retrospectively reviewed. There were 66 males and mean age was 28 years. Stab wounds were the most frequent mechanism of injury, occurring in 46 cases. Most of the injuries were treated using simple suture and minor debridement. Postoperative morbidity rate was 30 per cent and thoracic complications occurred in 11 patients. Twenty-six patients had diaphragmatic injuries; 54 per cent of them developed postoperative complications. Of the remaining 47 patients without diaphragmatic injuries, only eight developed complications. Of the 26 patients with diaphragmatic injuries, seven developed pleuropulmonary complications compared with 4 of 47 without diaphragmatic injury. Of sixteen patients who had gross contamination secondary to gastric injury, characterized by the presence of food or great amounts of gastric contents in the peritoneal cavity, 10 developed postoperative complications compared with 12 of 57 without gross contamination. Overall mortality rate was 11 per cent mostly due to sepsis. In conclusion, the presence of a diaphragmatic injury as well as gross contamination of the abdominal cavity are important factors related to the development of postoperative infections particularly in the pleural space.

Surgical antibiotic prophylaxis

Improvements in antibiotic prophylaxis, including the timing of initial administration, appropriate choice of antibiotic agents, and the limiting of the duration of administration, have more clearly defined the value of this technique in many clinical surgical settings. Studies of antibiotic prophylaxis designed during the next decade should strongly consider individual patient risk factors when new antibiotic agents are tested or administration techniques are refined. A concentrated effort should be made in areas of clinical surgery in which the value of antibiotic prophylaxis has not been proven. When in doubt, it appears that a one-dose systemic regimen of an appropriately chosen cephalosporin given during the immediate preoperative period is safe and the indicated practice.

Intra-abdominal sepsis

This article addresses controversial issues in the field of intra-abdominal sepsis with particular attention to major changes in management that have evolved during the past decade. In the area of diagnostics, scanning techniques have revolutionized the ability to detect loculated collections, although many of these techniques are of limited value in the early stages of inflammation. The greatest debate concerns the relative merits of scanning techniques; the author's choice is CT scans with contrast, although ultrasonography is preferred in patients who cannot be transported and is probably preferred for pelvic infections. In the area of therapeutics, virtually all studies seem to show that single-drug treatment is as effective as dual combinations or triple-combination therapy that has been standard practice in the past with the proviso that the drug used has activity versus Enterobacteriaceae and B. fragilis. The role of enterococcus remains enigmatic; this organism was readily discounted as an important pathogen in the great majority of cases 10 years ago, but it has subsequently become a major nosocomial pathogen that now commands newfound respect. P. aeruginosa is also controversial, but most studies show that antipseudomonad treatment is not necessary in the empiric selection of drugs and may not be necessary even when P. aeruginosa is found at infected sites; the corollary to this is that aminoglycosides may no longer be required in the dual drug treatment regimens. There is increasing resistance by B. fragilis and some other species of Bacteroides to some of the drugs considered "standard" in the past, including clindamycin, cefoxitin, and cefotetan; nevertheless, it has been difficult to demonstrate that resistance of these organisms correlates with antibiotic failure. It was demonstrated 20 years ago that elective colon surgery must be accompanied by preoperative antibiotics, and erythromycin plus neomycin has evolved as the regimen of choice according to recommendations of authoritative sources for the past 20 years. Nevertheless, surveys of practicing surgeons indicate that most actually combine this oral preparation with parenteral agents as well. The final controversy concerns percutaneous drainage, which has now become a standard technique for dealing with intra-abdominal abscesses in 50% to 90% of cases. This controversy has sometimes been seen as a territorial battle between surgeons and radiologists, and most cases are clearly the prerogative of one discipline or the other, but many are in a gray zone in which clearly defined indications are not readily available.

Preventive antibiotic usage in traumatic thoracic injuries requiring closed tube thoracostomy

OBJECTIVE

To evaluate the safety and effectiveness of antibiotics in reducing the infectious complications following closed tube thoracostomy for isolated chest trauma.

DESIGN

Double-blind, randomized clinical trial.

SETTING

Medical school affiliated large urban teaching hospital and trauma center.

PATIENTS

One hundred nineteen of 159 patients over 18 years old presenting to the emergency department requiring closed tube thoracostomy for isolated chest injuries (113 penetrating, 6 blunt).

INTERVENTION

Patients received either placebo or 1 g cefonicid daily intravenously started at chest tube insertion and stopped within 24 h of removal.

MEASUREMENTS AND RESULTS

The development of wound infections, pneumonia (CDC criteria), or empyema; the incidence of adverse events; length of hospitalization. One nonspecific infection was seen in the cefonicid group (1.6 percent) and six respiratory tract infections (10.7 percent) in the placebo group (three empyema, one empyema with pneumonia, two pneumonia) (p = 0.0505; p = 0.0094 [excluding nonspecific infection]). No significant differences with antibiotic use were seen in the duration of chest tube use (p = 0.766), peak WBC counts (p = 0.108), lower peak temperatures (p = 0.063), or length of hospitalization (p = 0.165). Patients who developed infectious complications averaged approximately 8 days longer hospitalization than those without (p < 0.0001).

CONCLUSION

This study showed that patients receiving antibiotics had a significantly reduced rate of infection than did patients administered placebo. No significant adverse events were seen in either group.

Transfusion-associated bacterial sepsis

The incidence of sepsis caused by transfusion of bacterially contaminated blood components is similar to or less than that of transfusion-transmitted hepatitis C virus infection, yet significantly exceeds those currently estimated for transfusion-associated human immunodeficiency and hepatitis B viruses. Outcomes are serious and may be fatal. In addition, transfusion of sterile allogenic blood can have generalized immunosuppressive effects on recipients, resulting in increased susceptibility to postoperative infection. This review examines the frequency of occurrence of transfusion-associated sepsis, the organisms implicated, and potential sources of bacteria. Approaches to minimize the frequency of sepsis are discussed, including the benefits and disadvantages of altering the storage conditions for blood. In addition, the impact of high levels of bacteria on the gross characteristics of erythrocyte and platelet concentrates is described. The potentials and limitations of current tests for detecting bacteria in blood are also discussed.

Piperacillin/tazobactam in the treatment of polymicrobial infections

Polymicrobial infections are characterized by the presence of micro-organisms from more than one group of bacteria. Empirical treatment of polymicrobial infections requires an agent active against both anaerobic and aerobic/facultative bacteria. An aminoglycoside used in combination with an anti-anaerobe agent is commonly used to treat polymicrobial infections. However, aminoglycoside nephrotoxicity and treatment failures raise questions about the use of such regimens. Among non-aminoglycoside treatment regimens such as penicillin and cephalosporins, effectiveness has been compromised by bacteria producing extended spectrum beta-lactamases. Cefoxitin shows satisfactory results for treatment of intra-abdominal infections. Other studies have shown good results with imipenem, cefotetan and piperacillin used as single agents. Piperacillin/tazobactam, a new combination broad-spectrum antibiotic and potent beta-lactamase inhibitor, can be used for the treatment of infections caused by piperacillin-sensitive micro-organisms as well as beta-lactamase-producing, piperacillin-resistant organisms. This broad-spectrum activity is appropriate for infections traditionally treated empirically by double or triple antibiotic therapy.

Pneumonia in the surgical intensive care unit. Immunologic keys to the silent epidemic

OBJECTIVE

The authors undertook a prospective study of trauma victims in the intensive care unit (ICU) to investigate the clinical course of pneumonia and the local and systemic immune responses to the pneumonia.

SUMMARY BACKGROUND DATA

The silent epidemic of pneumonia has been an "unappreciated killer" in terms of being overlooked in surgical ICUs for the past 5 years, and specifically, the most common major infection after severe trauma. Little is known about the immune response to an acute pulmonary infection.

METHODS

The authors studied 50 consecutive, critically ill trauma patients, with a mean injury severity score of 28 +/- 2, who developed pneumonia while ventilated mechanically. Patients were observed clinically, and specific immunologic parameters, including major histocompatibility antigen HLA-DR, complement receptor (CR3), and Fc receptor (FcRIII), were measured in circulating and local alveolar leukocytes for up to 30 days. Eleven patients provided unique clinical data via bronchoscopy for unilateral pneumonia, with collection of bronchoalveolar lavage (BAL) fluid from both the infected and uninfected sides.

RESULTS

Patients developed clinical pneumonia 5.3 +/- 0.4 days after admission to the ICU. At diagnosis, mean temperature was 101.4 F, white blood cell count was 16,000/mm3, arterial oxygen tension was 104 +/- 14, fraction of inspired oxygen was 0.47, and positive end-expiratory pressure was 5. Thirty patients (Group A) recovered relatively promptly; 20 patients had prolonged illnesses (Group B), 15 of whom ultimately survived, and five of whom died. Patients with poor outcomes had greater leukocytosis (p < 0.05) and temperature elevation (p < 0.05) after 5 days of pneumonia. Immunologically, peripheral leukocyte expression of HLA-DR, FcRIII, and CR3 was equivalent in both groups. However, the expression of all three antigens on local alveolar leukocytes was decreased to a greater extent in the poor outcome group compared to the good outcome group, evident before any clinical differentiation between the two outcome groups.

CONCLUSIONS

Pneumonia prolonged duration of mechanical ventilation, ICU and hospital stay, and overall infectious morbidity. Although immune suppression has been recognized as a result of initial injury, the development of pneumonia coincided with the nadir of immune function. Poor outcome patients were clinically identifiable 5 days after pneumonia and immunologically identifiable within 2 days. Moreover, there was localized suppression of pulmonary leukocytes at the site of the infiltrate compared to the uninfected lobes. This same alteration was noted in experimental Klebsiella pneumoniae pneumonia. This evidence suggests that there is active immune participation within the respiratory system. It also suggests that there are predispositions to pulmonary infections, and it may allow immune modulation targeted to pulmonary leukocytes to hasten clinical recovery and minimize pulmonary dysfunction.

Infectious disease markers in autologous and directed donations

Autologous collections are strongly advocated by the New South Wales Red Cross Blood Transfusion Service (BTS) and have increased more than sevenfold since 1988. Directed donations, although not promoted, have also increased during this time. The prevalence of infectious disease markers (HIV, hepatitis C, hepatitis B and syphilis) in donations collected by the BTS from different donor groups including overall volunteer homologous, first-time volunteer homologous, autologous and directed were evaluated over a 42-month period. Donations from first-time volunteer homologous donors had the highest prevalence of hepatitis B and C. Autologous donations had a significantly higher prevalence of hepatitis B, hepatitis C and syphilis compared with overall volunteer homologous donations. The percentage of directed donations testing positive for either hepatitis B or C was higher than overall volunteer homologous donations, but not statistically significant. This study demonstrates that donations from first-time donors are the least safe, that the crossover of autologous blood into the volunteer homologous pool decreases the safety of that pool and suggests that directed donations may not be as safe as volunteer homologous donations and cannot be generally advocated at this time.

[Antibiotic prophylaxis in multiple trauma patients]

Infection prophylaxis in multiple trauma patients includes prophylaxis of infections due to surgery, which is the true one as well as the prophylaxis of secondary acquired infections which are more frequent, especially in case of co-existing shock. The association an aminopenicillin with a beta-lactamase inhibitor is recommended for prophylaxis of surgical infections. These antibiotics need to be administered early and in high doses, as the pharmacokinetic parameters are modified in trauma patients, with an increased volume of distribution and a shortened half-life of elimination. Prevention of secondary infection relies on a medico-surgical treatment of haemorrhagic shock. Other preventive measures, such as early enteral nutrition, selective decontamination of the digestive tract and immunotherapy, still need to prove their efficacy.

Macrophage prostaglandin E2 and oxidative responses to endotoxin during immunosuppression associated with anaesthesia and transfusion

The widespread use of blood transfusion in major surgical procedures has led to concern about the immunosuppressive effect of transfusion on patients with underlying malignancy. Transfusion may also suppress the host response to infection. The cellular mechanisms of transfusion-associated immunosuppression may involve macrophage prostaglandin E2 (PGE2) in modulating the host response to cancer and infection. We previously observed that the transfusion of blood increased PGE2 production by unstimulated macrophages. To investigate this PGE2 associated immunosuppression, we studied the effect of transfusion of rats using a physiological stimulus of macrophage PGE2 production, bacterial endotoxin. In the same macrophages, we analysed intracellular oxidative activity. Both allogeneic and syngeneic blood transfusion were associated with increased PGE2 release by macrophages. This stimulation of PGE2 increased with duration of storage of blood. A similar effect of serum indicated that a humoral factor was involved. Endotoxin (50 ng/ml-500 micrograms/ml) stimulated PGE2 production in all transfused subjects. The lowest endotoxin concentration gave proportionately the greatest stimulation. Oxidative activity was down-regulated in macrophages of transfused rats, supporting an immunosuppressive role of PGE2 within the macrophage. An effect of surgery on the oxidative response was also detected.

Gunshot wounds of the colon: role of retained bullets in sepsis

The role in the development of local sepsis of retained bullets that have passed through the colon was investigated. Of 84 patients with gunshot wounds of the colon, the bullet was retained in the body in 40 and had left or was removed from the body in 44. The groups were similar with regard to Revised Trauma Score, Injury Severity Score, Penetrating Abdominal Trauma Index and type of colonic trauma. The incidence of major local complications was 5 per cent in patients with a retained bullet and 7 per cent in those without. These results suggest that retained bullets that have penetrated the colon do not contribute to local septic complications.

Empiric antibiotic therapy of abdominal sepsis and serious perioperative infections

This article discusses empiric therapy for several serious infections in surgical patients. The accepted antibiotic treatment for purulent peritonitis, the empiric treatment of postsurgical wound infection, and the empiric treatment of postsurgical pneumonia are discussed. The cost of the various regimens is listed. Recommendation of the various regimens is based on the seriousness of the infection, peculiarities of the hospital flora, effectiveness of the regimens, and cost.

Mechanism of increased susceptibility to infection following hemorrhage

Although hemorrhage is known to cause increased susceptibility to infection, the precise mechanism remains unknown. Regional hypoxia due to reduced blood flow following hemorrhage appears to be a primary mediator that initiates the cascade of events leading to immunodepression and increased susceptibility to infection. This was evident from depression of lymphocyte functions, production of various lymphokines, macrophage expression of receptors involved in opsonin-mediated phagocytosis, and antigen presentation function of peritoneal, splenic, and Kupffer cells following hemorrhage. The depression in various immune functions is apparent immediately after hemorrhage and persists for a prolonged period of time, despite volume resuscitation. Furthermore, it appears that the increased release of systemic mediators, such as interleukin-1 (IL-1), IL-6, tumor necrosis factor, transforming growth factor type beta, and prostaglandin E2 is associated with marked depression in immune responses and increased susceptibility to infection following hemorrhage.

Predicting infectious morbidity in elective operations

The determination of surgical risk is a major problem in general surgical practice and many studies have attempted to predict postoperative outcome. Clinical judgment is still a fundamental skill with which the experienced surgeon can estimate the risk of postoperative infectious morbidity. Predictive scores based on statistical analysis have also proven to be valid and useful tools. This discussion analyzes the importance of surgical risk prediction. With future research in this area, it is hoped that therapeutic strategies will result that will reduce or eliminate this risk.

Perioperative haemotherapy: II. Risks and complications of blood transfusion

Major life-threatening complications following blood transfusion are rare and human error remains an important aetiological factor in many. The infectious risk from blood transfusion is predominantly hepatitis, and non-A, non-B and hepatitis C (HCV) are the most common subtypes noted. The risk of post-transfusion hepatitis (PTH) appears to be decreasing and this is attributed to both deferral of high-risk donors and more aggressive screening of donated blood. Screening for HCV is expected to decrease this risk further. The risk of HIV transmission following blood transfusion is negligibly small. There are data to suggest that perioperative blood transfusion results in suppression of the recipient's immune system. Earlier recurrence of cancer and an increased incidence of postoperative infection have been associated with perioperative blood transfusion although the evidence is not persuasive. Microaggregate blood filters are not recommended for routine blood transfusion but do have a role in the prophylaxis of non-haemolytic febrile reactions caused by platelet and granulocyte debris in the donor blood. Patients should be advised when there is likely to be a requirement for perioperative blood transfusion and informed consent for transfusion should be obtained.

The Immunosuppressive Aspects of Blood Transfusion

Blood transfusion is associated with immunosuppression, although the exact etiology of the immunosuppressive effect is not fully understood. The clinical significance of the immunosuppressive effect of blood transfusion has been examined in three situations: (1) studies of renal allograft survival after renal transplantation, (2) outcome studies in patients who have had surgical resection of solid cancer tumors, and (3) studies of infection rates in postoperative patients. In each scenario, the data support the conclusion that transfusion is associated with immunosuppression as manifested by increased renal allograft survival, increased recurrence and mortality rates in patients with cancer, and increased infection rates in postoperative patients who are transfused. Not all studies demonstrate an immunosuppressive effect of transfusion. There are several possible explanations for these discrepancies. First, prognostic variables other than transfusion itself account for the outcome results in these retrospective studies. Second, the extent of immunosuppression may be influenced by the type of blood product transfused, the amount transfused, and the timing of the transfusion; these factors have not been considered in all studies. For example, whole blood has been implicated as having a greater immunosuppressive effect than packed red blood cells, and many studies have shown that more than three units of packed red blood cells are necessary to affect outcome. Controlled animal studies have tested the hypothesis that transfusions increase solid tumor growth or the risk for infection. These studies have yielded conflicting results. Nevertheless, evidence that blood transfusion influences clinical outcome mitigates that a decision to transfuse must consider both risks and benefits of a transfusion; the possible consequences of immunosuppression must be included among the risks. Use of autologous blood, erythropoietin, and, in the future, synthetic hemoglobin may lead to improved outcome in patients with certain disease processes.

Lipopolysaccharide-tumor necrosis factor-glucocorticoid interactions during cecal ligation and puncture-induced sepsis in mature versus senescent mice

Previous work in our laboratory demonstrated increased sensitivity of senescent (24-month-old) mice to cecal ligation and puncture (CLP) sepsis compared with that of mature (12-month-old) mice. In this study the median lethal dose of the strain of Escherichia coli most frequently isolated during CLP sepsis was determined. No significant age-associated difference in the mean lethal dose or the mean survival time was noted; however, sham surgery before injection of E. coli decreased the mean lethal dose by at least 100-fold. With surgical manipulation, the average time to death after bacterial injection simulated more closely that observed after CLP surgery. Host responses to CLP sepsis were investigated by measuring the levels of corticosterone, glucose, and tumor necrosis factor (TNF) in the sera of mature and senescent mice at 2-h intervals after surgery. Corticosterone levels increased gradually during the course of sepsis in mature mice; however, senescent mice demonstrated a pronounced elevation in hormone levels at 2 and 4 h after surgery. At subsequent sampling intervals the corticosterone levels remained elevated, although they were similar for both ages. At all sampling intervals, the glucose levels in serum were lower in senescent mice than in mature mice. Pronounced hypoglycemia (less than 80 mg/dl) was observed in senescent mice at 8 h postsurgery. TNF was detected in serum within a narrow time frame in both age groups at 6, 8, and 10 h postsurgery. Although elevated TNF levels in serum were not seen in every mouse in each group (approximately 50%), the data hinted that senescent animals produced larger quantities of TNF during CLP sepsis than did mature animals. E. coli lipopolysaccharide (1 mg/kg) was injected intraperitoneally, and the TNF levels in serum and peritoneal lavage fluid were measured at 30, 60, and 90 min. Senescent mice demonstrated a level of TNF in serum at 90 min after lipopolysaccharide treatment that was 20-fold higher than that of mature mice (299,877 pg/ml versus 15,594 pg/ml). The amount of TNF produced locally in the peritoneum was also substantially higher in senescent mice than in mature animals (1,716 pg/ml versus 776 pg/ml). The increased production of TNF in senescent animals, despite elevated circulating corticosterone levels, suggested an age-related defect in glucocorticoid-directed downregulation of TNF production. This was confirmed in lipopolysaccharide-treated animals given exogenous dexamethasone.(ABSTRACT TRUNCATED AT 400 WORDS)

Computerized identification of patients at high risk for hospital-acquired infection

Surveillance for hospital-acquired infections is required in U.S. hospitals, and statistical methods have been used to predict the risk of infection. We used the HELP (Health Evaluation through Logical Processing) Hospital Information System at LDS Hospital to develop computerized methods to identify and verify hospital-acquired infections. The criteria for hospital-acquired infection are standardized and based on the guidelines of the Study of the Efficacy of Nosocomial Infection Control and the Centers for Disease Control. The computer algorithms are automatically activated when key items of information, such as microbiology results, are reported. Computer surveillance identified more hospital-acquired infections than did traditional methods and has replaced manual surveillance in our 520-bed hospital. Data on verified hospital-acquired infections are electronically transferred to a microcomputer to facilitate outbreak investigation and the generation of reports on infection rates. Recently, we used the HELP system to employ statistical methods to automatically identify high-risk patients. Patient data from more than 6000 patients were used to develop a high-risk equation. Stepwise logistic regression identified 10 risk factors for nosocomial infection. The HELP system now uses this logistic-regression equation to monitor and determine the risk status for all hospitalized patients each day. The computer notifies infection control practitioners each morning of patients who are newly classified as being at high risk. Of 605 hospital-acquired infections during a 6-month period, 472 (78%) occurred in high-risk patients, and 380 (63%) were predicted before the onset of infection. Computerized regression equations to identify patients at risk of having hospital-acquired infections can help focus prevention efforts.

The effect of fibrin glue on intraperitoneal contamination in rats treated with systemic antibiotics

Intraperitoneal fibrin sealant lowers septic mortality in a rat model of peritoneal contamination (2 x 10(6) organism inoculum) at the cost of increased late intraabdominal abscesses. This study utilized parenteral antimicrobials to determine if the protective effect of intraperitoneal fibrin could be achieved without increasing the late abscess formation rate. One hundred and fifty-five rats were divided into four groups. Gelatin capsules containing various dilutions of feces (10(10) CFU/ml) and barium sulfate were placed into the abdomen in all groups. Group I controls had no antibiotics or fibrin. In group II, the capsule was surrounded by a solution of cryoprecipitate, thrombin, and calcium (fibrin "glue"). Groups III (no fibrin, antibiotics) and IV (fibrin, antibiotics) received a broad-spectrum cephalosporin intramuscularly postoperatively and then daily. Surviving rats were sacrificed on the tenth postoperative day. At a moderate volume of fecal inoculum (0.3 ml), fibrin reduced mortality from 100% in the control group to 0% in treated animals (P less than 0.001) that did not receive antibiotics. Abscesses formed in 10% of the surviving fibrin-treated rats which were implanted with 0.1 ml of inoculum. In the 0.2 and 0.3 ml inoculum groups substantially more abscesses occurred (75 and 70%, respectively). The protective effect of fibrin was not manifested in the antibiotic-treated rats since no deaths occurred in either group. At higher and lower inoculum doses, no significant differences between fibrin and control groups were observed in mortality or abscess formation, whether or not antibiotics were given.(ABSTRACT TRUNCATED AT 250 WORDS)

Pelvic abscess or pseudoaneurysm: diagnostic and therapeutic dilemma following iliac arterial trauma

Intra-abdominal abscesses often complicate operations for abdominal trauma and are particularly dangerous in patients whose injuries involve major vessels. We report our experience with 10 patients who developed pelvic abscesses among 75 survivors of iliac arterial injuries. Pseudoaneurysms of primarily repaired iliac arteries occurred in 8 of these 10 patients. Emergency operations were required for acute arterial thrombosis or hemorrhage in four patients; massive hemorrhage that complicated the drainage of pelvic abscesses led to the recognition of the pseudoaneurysms in the other four patients. Three of the eight patients with pseudoaneurysm died of postoperative complications; ischemic extremity sequelae occurred in all five survivors. The association of pelvic abscesses with the complications iliac arterial repairs has not been previously emphasized. The integrity of an arterial repair should be arteriographically confirmed before proceeding with drainage of a pelvic abscess that developed after iliac arterial trauma.

Antibiotic treatment for surgical peritonitis

The charts of 480 patients with secondary bacterial peritonitis were reviewed. The antibiotics used were compared with the culture and sensitivity data obtained at surgery, and the outcomes of patients were evaluated. Patients treated with a single broad-spectrum antibiotic had a better outcome than patients treated with multiple drug treatment. Inadequate empiric antibiotic treatment was associated with poorer outcome than any other type of treatment. The outcome of this inadequate treatment group could not be improved by any antibiotic response to culture and sensitivity information after operation. Those patients treated with antibiotic coverage for anticipated organisms and having no cultures taken did as well as patients having cultures taken. Surgeons typically ignore culture data after operation, and only 8.8% of patients in this study had an appropriate change in antibiotic treatment after operation. A benefit from obtaining operative cultures could not be identified.

Surgical wound infection

Wound infections remain a major source of postoperative morbidity, accounting for about a quarter of the total number of nosocomial infections. Today, many of these infections are first recognized in the outpatient clinic or in the patient's home due to the large number of operations done in the outpatient setting. This leads to errors in establishing the true incidence of their occurrence but undoubtedly decreases the overall real cost and length of hospital stay. The pathogens implicated in the development of wound infections remain largely the human microorganisms from the exogenous environment and the endogenous organ microflora. Many perioperative factors have been identified that increase the incidence of the development of postoperative wound infection. Avoidance of these factors as well as the appropriate use of perioperative antibiotic prophylaxis has decreased the incidence of wound infection. During the last decade many studies have reported on the individual risk factors that favor the development of postoperative infectious complications in various surgical procedures. It is hoped that this knowledge may allow for prospective alterations in the preventative and therapeutic modalities in the high-risk patient in the studies designed in the 1990s. The use of effective infection surveillance both in the hospital and in the outpatient setting is mandatory in order to collect meaningful data. The use of computer technology will greatly facilitate the proper surveillance, analysis, and control of infections in the surgical patient.

Nosocomial infections in surgical patients: developing valid measures of intrinsic patient risk

For surgeons or hospitals to compare their rates of wound infection meaningfully, the analysis must first control for the mix of intrinsic infection risk of their patients. Research over the past century has led to the development of several intrinsic risk indexes that can be used to stratify the wound infection rates so that valid comparisons can be made within risk strata. For an intrinsic risk index to be useful for comparing rates, it must control for all of the important intrinsic risk constructs; merely being statistically associated with infection rates does not ensure that a risk index will be useful. Understanding how a risk index can be both parsimonious and comprehensive requires consideration of the competing principles of multicollinearity and orthogonality. Various techniques of multivariate analysis are used to develop multivariate risk indexes, but the success of the process depends on having all of the important orthogonal risk constructs represented in the pool of predictor variables available for the analysis, either directly by variables in the pool or by demonstrated multicollinearity. Despite recent advances in risk measurement, many important questions remain.

Reoperation for intra-abdominal abscess

Reoperative procedures for patients with abscess and other septic complications remain among the most difficult management problems in general surgery. The diagnosis of intra-abdominal septic complications has been greatly enhanced within the last 10 years but remains imperfect and requires clinical judgment that transcends objective methods. Surgical drainage remains the mainstay of care for patients with postoperative intraabdominal abscess.

Short-course antibiotic prophylaxis in penetrating abdominal injuries: ceftriaxone versus cefoxitin

This was a prospective, randomized study of 123 patients with penetrating abdominal injuries. The patients received ceftriaxone or cefoxitin for 24 h (in the presence of colonic injury, 48 h). The overall incidence of abdominal sepsis was 7.3 per cent (ceftriaxone 5 per cent, cefoxitin 9.5 per cent, P greater than 0.05). Colonic injury was the most important risk factor for the development of septic complications. Other factors, such as the weapon used, a prehospital time longer than 4 h, shock on admission, multiple organ injuries, and small bowel perforation, did not influence the incidence of sepsis.

Trend toward nonoperative management of splenic injuries

Treatment of splenic injuries has evolved over the past decade to reflect more effort to conserve function of the spleen. Records of 169 patients admitted over a 6-year period were identified as documenting the treatment of splenic injuries. We collected data regarding patient age, gender, degree of hemodynamic stability, number of units of blood required, severity of splenic injury, Injury Severity Score, and results of treatment. There were 143 adults (age greater than 16 years) and 26 pediatric patients (age less than 17 years), with mean age in the 2 groups of 31.6 and 11.4 years, respectively. Males comprised 72% of the group, and blunt injury occurred in 154 of the 169 patients. In the adults, splenectomy, splenorrhaphy, laparotomy without operative treatment of the spleen, and nonoperative management were observed 48%, 30%, 14%, and 8% of the time and in the pediatric group 31%, 27%, 19%, and 23% of the time, respectively. By using operative splenic repair techniques and increased use of nonoperative management, the splenic salvage rate has increased in the last 6 years from 41% to 61% without an increase in morbidity and mortality. Incidence of spleen salvage correlated with severity of spleen and overall injury and cardiovascular stability.

Hematuria-A Diagnostic Challenge

In brief Athletes are prone to hematuria from diverse causes, and proper diagnosis hinges on a careful history, physical examination, and urinalysis, as well as on judicious use of screening tests, imaging studies, and cystoscopy. Using six illustrative cases, this article covers the adult athlete with hematuria: real and false, normal and abnormal, microscopic and gross. It focuses on when and how to evaluate hematuria, and offers practical tips on management.

Cefoxitin in the prevention and treatment of infections

A review of the literature indicates that cefoxitin is an effective single-agent therapy for community-acquired intra-abdominal infections, pelvic infections, and surgical prophylaxis. Hospital-acquired intra-abdominal infections may require the addition of an aminoglycoside.

Transfusion-induced immunomodulation and its clinical consequences

The bulk of experimental and clinical data support the theory that homologous transfusion causes significant down-regulation of immunologic functions in a number of settings. These changes in immune function may account for the beneficial associations of transfusion with increased renal allograft survival, and decreased recurrence in Crohn's disease. Conversely, these transfusion-induced effects may be responsible in part for the deleterious association of homologous transfusion with increased cancer recurrence, and increased posttransfusion bacterial and viral infection rates. Host defenses against malignancy and infection may in some instances be severely compromised by transfusions of homologous blood, but the circumstances under which this occurs need to be better defined. Likewise, the hypothesis that modification of blood components to contain fewer leukocytes or less plasma might ameliorate these effects is attractive, but little or no data exist to support or refute it. Future clinical studies will no doubt address these issues.

Colon wound management and prograde colonic lavage in large bowel trauma

Between 1983 and 1987 prograde colonic lavage was prospectively evaluated in 389 patients with colon trauma. Predefined high risk patients had exteriorization of the primarily sutured colon. Intraperitoneal primary closure was otherwise used. Patients received prograde colonic lavage by random allocation. The healing exteriorized colon was interiorized 5-10 days after the initial surgery. The median age was 29 years and only 28 patients were women. Injuries were due to stab (316), gunshot (54), shotgun (10) or blunt trauma (9). Exteriorization of the primarily sutured colon was carried out in 217 patients of whom 101 had prograde colonic lavage. Twenty (9 per cent) died. Of the survivors, 150 (76 per cent) had their colon successfully interiorized and this rate was unaffected by prograde colonic lavage. Intraperitoneal primary closure was performed in 172 patients of whom 91 had prograde colonic lavage. Seven (4 per cent) died. Mortality was directly related to the number of associated injuries. Prograde colonic lavage, irrespective of the type of colonic wound management used, did not reduce the mortality rate, which was 7.2 per cent for those who had such lavage and 6.6 per cent for the rest. Prograde colonic lavage cannot therefore be recommended in colon trauma.

Intra-abdominal abscess after blunt abdominal trauma

The relationship between blunt abdominal trauma and intra-abdominal abscess (IAA) is discussed infrequently; therefore we conducted a retrospective review of 4050 multiple blunt trauma admissions from January 1986 to July 1988. Of 325 patients who had a laparotomy for blunt abdominal trauma, we identified 15 (4.6%) who had 40 IAAs. The most common intra-abdominal injuries involved the spleen and liver. Splenectomy increased the risk for IAA in contrast to splenic salvage. Blunt injuries to the kidney and pancreas, when occurring in multiple trauma patients, carried a significant risk of IAA. Associated multiple extra-abdominal injuries and high transfusion requirements increased the risk for IAA formation. Most of the IAAs were located in the upper quadrants. There was a 46% incidence of multiple IAA, which in turn had an 80% chance of recurrence after initial drainage. Enterobacter species played an important role in the formation of IAA in our trauma patients. Three patients (20%) died. Poor prognostic indicators included a high injury severity score, high transfusion requirements, the presence of pelvic fracture, positive blood cultures, multiple organisms per abscess, and multiple-organ system failure.

Intraoperative blood salvage: medical controversies

Although a great deal has been learned about the medical aspects of intraoperative blood salvage, several fundamental medical issues remain controversial. As pressure increases to maximize the use of IBS, more research will be needed on the application of salvage techniques in cancer surgery and in the presence of bacterial contamination. The reintroduction of the use of devices that do not wash salvaged blood have reopened investigations into the effects of reinfusion of partially hemolyzed and partially clotted salvaged blood on coagulation, renal function, and cardiopulmonary performance. More studies are also needed so that empirically based standards of practice for the collection and storage of salvaged blood can be established. No longer confined to a few pioneering surgical departments, IBS is now widely practiced and likely to continue to grow rapidly. Knowledge and research of the medical issues surrounding its use will become increasingly valuable in transfusion medicine.

Pre-, intra-, and postoperative antibiotics

Endogenous contamination from perforation or rupture of the gastrointestinal tract; exogenous contamination from missiles, knives, or invasive lines and tubes; and immunodepression related to the severity of injury are responsible for the increased infectious complications noted in patients who have undergone laparotomy for abdominal trauma. Perioperative use of clindamycin and an aminoglycoside, a second- or third-generation cephalosporin, or an enhanced-spectrum penicillin is clearly beneficial in lowering the incidence of intra-abdominal and wound infections. A 12- to 48-hour length of administration of antibiotics after operation is as effective as regimens of longer duration, although presently used dosages may be inadequate in severely injured patients. Adjunctive surgical maneuvers such as peritoneal irrigation with saline-containing antibiotic(s) remain controversial. Perioperative use of antibiotic prophylaxis, coupled with early operation and appropriate surgical technique, results in a 4.4% rate of intra-abdominal abscesses and a 5.1% rate of wound infections after laparotomy for abdominal trauma in modern trauma centers.

Variable infection risk following allogeneic blood transfusions

These studies address infection risk of allogeneic transfusion in an untraumatized, nonseptic rodent model. A' Segaloff Cancer Institute rats served as blood donors and Lewis rats as recipients. Lewis rats' delayed-type hypersensitivity (DTH) response and their ability to clear subdermal Staphylococcus aureus abscesses and Candida albicans pyelonephritis were measured as tests of the effect of transfusions. The effect of pharmacological immunosuppression with either cortisone acetate or cyclosporine provided a "yardstick" to measure the magnitude of transfusion effects. Repeated transfusions at 1-week intervals diminished DTH response to recall antigens (keyhole limpet hemocyanin), but otherwise they showed no evidence of immunosuppression in these experiments. In contrast, we found that transfusions by themselves produced mild immunostimulation. Subcutaneous Staphylococcus abscesses were smaller in animals receiving transfusions. The magnitude of immunostimulation from one transfusion was sufficient to reverse the immunosuppressive effect of cyclosporine by about 50% in a Candida pyelonephritis infection. These studies suggest that blood transfusions have complex interactions with different components of the immune response. T-cell function is impaired by repeated transfusions (diminished DTH response), but other inflammatory responses are accentuated. This suggests that blood transfusions may harm immune response in traumatized animals by causing excessive complement activation or cytokine release.

Proposed definitions for diagnosis, severity scoring, stratification, and outcome for trials on intraabdominal infection. Joint Working Party of SIS North America and Europe

Analysis of the experience with scientific studies on patients with secondary intraabdominal infection has revealed that problems of interpretation and comparability between studies exist as they relate to variable diagnostic criteria, unmeasured severity of disease, and unclear outcome measures. A consistent system of definitions has been developed to address these deficiencies. Intraabdominal infection is defined as clinical peritonitis requiring both operative and microbiological confirmation for proof of infection. The APACHE II system is proposed for grading the severity of the infection and for stratification of patient risk of mortality. Mortality and time until death, on one hand, and recovery and time until recovery, on the other, are proposed as the main outcome measures, both being independently and positively defined. It is anticipated that this system of minimum rules will produce studies that can be compared, hence, accelerating knowledge and understanding about intraabdominal infection and its best treatment.

Mortality and bacteriology of sepsis following cecal ligation and puncture in aged mice

Epidemiologic data suggest that elderly adults are more susceptible to invasive bacterial infection by indigenous gut flora than are younger adults. The purpose of this investigation was to characterize a murine model of clinically encountered peritonitis in the aged. We subjected three different age groups (young, 16 weeks; mature, 12 months; senescent, 24 months) of C57BL/6NNia mice to surgically induced peritonitis by the cecal ligation and puncture procedure. Senescent mice died in a significantly shorter time following surgery than mature mice (median time to death, 24.4 versus 38.5 h, respectively; P less than or equal to 0.001). Blood, liver, spleen and occasionally, ceca were obtained at 2 and 12 h after the cecal ligation and puncture procedure and immediately following death, to characterize the bacterial kinetics of the model. Qualitative and quantitative aerobic, anaerobic, and coliform cultures were performed. No age-related differences were found in the types of bacteria isolated throughout the time course of progressive sepsis. In mice in the mature and senescent age groups, at 2 and 12 h postsurgery, gram-negative anaerobes and gram-positive aerobes predominated in all tissues that were cultured. At the time of death, however, blood and tissue isolates consisted predominantly of coliform bacteria. The shift from mixed infection during sepsis to predominantly gram-negative bacterial infection reflected a similar progressive shift in bacterial types found in the cecum. At death, senescent mice had 100-fold fewer coliform bacteria in the bloodstream than those found in mature mice (2.5 x 10(9) versus 4.6 x 10(11), respectively). The increased sensitivity of aged mice to invasive bacterial infection documented in this series of experiments accords well with human epidemiologic experience and demonstrates the appropriateness of the model for continued investigations of sepsis in the aged.

Monocyte HLA-DR antigen expression characterizes clinical outcome in the trauma patient

Immunological assessment is important to characterize the host defence response of trauma patients as infection is the most common cause of severe morbidity and late death. Sixty trauma patients were followed serially and divided into three groups: those with an uneventful recovery (n = 17), those with recovery after major sepsis (n = 27) and those who died (n = 16). The ability of peripheral blood monocytes to express the antigen HLA-DR was measured and compared to the results from 77 asymptomatic volunteers. After initial injury, there was a significant reduction from normal in the three trauma groups. It took one week for HLA-DR antigen expression to return to the normal range in the first group, three weeks in the second group, and in the third group it never returned to normal. Monocyte HLA-DR antigen expression, after incubation with lipopolysaccharide, distinguished those patients who survived from those who died. There was no difference in HLA-DR antigen expression between a high transfusion group of 31 patients who received 10 or more units of blood and a low transfusion group of 29 patients who received less than 10 units. The ability of monocytes to express HLA-DR antigen correlated directly with the clinical course in these patients and its measurement identified a group of patients at high risk of infection and death following trauma.