Contributions to the management of intraabdominal infections

Intraabdominal infection represents a spectrum of diseases with a common pathogenesis. Establishing a prompt diagnosis and avoiding treatment delays are keys to achieving the best outcomes. Mortality depends on initiating early appropriate treatment to restore fluid and electrolyte imbalances, supporting the function of vital organs, providing appropriate broad-spectrum antimicrobial therapy, and achieving adequate source control. Faculty from the Department of Surgery at the University of Louisville have made significant contributions to the understanding and management of intraabdominal infections that have affected clinical practice and patient outcomes.

Outcome of severe acute pancreatitis

BACKGROUND

The treatment of severe acute pancreatitis has been evolving from routine operative management to nonoperative care for patients without evidence of pancreatic infection.

METHODS

Retrospective chart review of patients with severe acute pancreatitis at a single institution during a 9-year period.

RESULTS

Sixty consecutive patients had severe pancreatitis. Forty-two had pancreatic necrosis on computed axial tomography (13 infected and 29 sterile). Patients with infected necrosis and 8 with sterile necrosis had operative debridement; the remaining patients were managed without operation (n = 39). The overall mortality was 15%. Mortality was directly related to the Acute Physiology and Chronic Health Examination II and Marshall organ failure scores (P <0.001). Patients who died had a greater incidence of nosocomial infection.

CONCLUSIONS

Patients with infected pancreatic necrosis require early operative debridement, whereas those with sterile necrosis or severe pancreatitis without necrosis can usually be managed safely without surgery.

Life after 80 Hours: The Impact of Resident Work Hours Mandates on Trauma and Emergency Experience and Work Effort for Senior Residents and Faculty

BACKGROUND

The purpose of this study was to evaluate the impact of work hours mandates on (1) senior resident patient exposure and operating experience in trauma and emergency surgery and (2) faculty work effort.

METHODS

We measured resident and faculty work on the trauma and emergency surgery services at our Level I trauma center during two comparable 6-month periods. Period 1 (July 1-December 31, 2002) had no call restrictions, separate trauma and emergency service resident call, and some overlap of faculty call responsibilities. Period 2 (July 1-December 31, 2003) had resident work hours compliance and complete integration of resident and faculty trauma and emergency call. Work hours were measured by surveys for faculty and residents. All data were collected prospectively.

RESULTS

Resident exposure to trauma patients was similar during both time periods. Emergency surgery admissions declined during period 2; however, intensive care unit admissions increased. The number of operations performed by senior residents did not change; however, there was a shift in the median number of emergency surgery cases to more senior residents. Faculty work hours increased slightly despite a decrease in faculty call.

CONCLUSION

Work hours compliance resulted in a 50% reduction in senior resident call and a 19% decrease in their work hours with no significant change in trauma/emergency patient care exposure or operative case load. Service call amalgamation reduced faculty call by 21% but did not result in a corresponding change in work hours or productivity.

Nosocomial Infections Adversely Affect the Outcomes of Patients with Serious Intraabdominal Infections

BACKGROUND

Patients with serious intraabdominal infections (IAI) who subsequently acquire nosocomial infections (NI) have been shown to have adverse outcomes. We evaluated factors that put patients at risk for developing NI and examined the effect of the NI on outcomes.

METHODS

This study was a retrospective review of NI among 168 patients diagnosed with IAI over a seven-year period.

RESULTS

Sixty-six patients (39.3%) developed 98 NI (23 urinary tract, 20 surgical site, 19 pneumonia, 14 bloodstream, 12 recurrent peritonitis, seven intravascular catheter-related, and three enteric). There were 35 males and 31 females. Patients with NI were older (56.0 +/- 18.3 vs. 47.0 +/- 15.6 years, p = 0.001), had a higher admission APACHE II score (10.7 +/- 6.1 vs. 7.5 +/- 5.1 points, p = 0.001), and more often had concomitant medical diagnoses (27.3% vs. 12.7%, OR = 2.57, 95% CI: 1.159-5.69, p = 0.018) than those who did not develop infection. Antimicrobial resistance among the IAI was higher in the NI group (19.7 vs. 5.9%, OR = 3.93, 95% CI: 1.41-10.93, p = 0.006). Patients who developed NI had an increased mortality rate (27.0% vs. 4.0%, OR = 8.87, 95% CI: 2.82-27.86, p < or = 0.0001), longer hospital stay (24.7 +/- 19.5 vs. 11.7 +/- 8.1 days, p < or = 0.0001), required more days of intravenous antibiotics (11.5 +/- 8.0 vs. 7.6 +/- 4.4 days, p < or = 0.0001), and were more likely to be admitted to an intensive care unit (54.5% vs. 25.5%, OR = 3.51, 95% CI: 1.82-6.77, p < or = 0.0001). Multivariate analysis demonstrated that antimicrobial resistance and an APACHE II score of > or = 10 independently predicted the development of a nosocomial infection. Age >/= 50 years, APACHE II score > or = 10, or the presence of a NI independently predicted death.

CONCLUSIONS

The development of NI following treatment of an IAI significantly affects mortality, hospital length of stay, and treatment. Early recognition and treatment of these infections, combined with strategies to prevent NI, may be important to improve outcomes in this patient population.

Current concepts in peritonitis

Peritonitis is a serious and common infection. Its pathogenesis and microbiology have been well defined. Such risk factors as age, site of infection, physiologic response of the patient, presence of organ dysfunction, and malnutrition may influence the outcome of this disease process. The presence of antibiotic-resistant organisms and delays in operative intervention are also associated with treatment failure and higher mortality. Surgeons have the greatest impact on this disease in their ability to control the source of infection and to administer proper antimicrobial therapy.

Continuing medical education activity and American Board of Surgery examination performance

BACKGROUND

Surgical knowledge is the basis of successful clinical problem solving, so is thought to be an important component of overall clinical ability. Continuing medical education (CME) reinforces basic knowledge and provides exposure to new knowledge within a field. Specialty board examination performance measures this knowledge but few studies have investigated a link between such performance and CME activity. This study assessed that link on the American Board of Surgery Recertification Examination.

STUDY DESIGN

The study sample comprised 278 randomly chosen applicants for the 2000 examination. Study variables included practice type, career activity, age, gender, other Board certifications, examination attempts, community size, geographic region, nationality, and ethnicity.

RESULTS

The study sample was remarkably similar to the total candidate cohort with regard to study variables. Of the 245 sample Diplomates who took the Recertification Examination, 10.2% failed. The Pass group reported 53% more total CME hours and 38% more Category I CME hours than the Fail group. The vast majority of Category I activities were surgical, clinical. Analyzed by quartiles of total CME hours, the failure rate was only 3.4% for the highest quartile but 25.8% for the lowest quartile. For Category I hours, respective failure rates were 4.8% and 19.4%. When further stratified by practice type, the failure rate of those in solo practice was 6% for those in the highest quartile of total CME hours and 37% for those in the lowest quartile. For Category I hours, the respective failure rates were 0% and 31%.

CONCLUSIONS

There is a strong relationship between CME activity and performance on the American Board of Surgery Recertification Examination. Low CME activity and practice type appear to be independent risk factors for examination failure. The relationship of these findings to patient care outcomes has important implications.

Necrotizing soft tissue infections: are we making any progress?

BACKGROUND

Necrotizing soft tissue infections are a group of diseases with significant associated mortality. A wide spectrum of bacteria can be involved, and diagnosis can be difficult.

METHODS

Review of pertinent literature of the diagnosis and therapy of necrotizing soft-tissue infection.

RESULTS

Mortality and other adverse outcomes are directly related to advanced age, the presence of organ system failure, lactic acidemia, the percentage of body surface area involved with infection, and delays in operative management. Patients usually die early from the consequences of septic shock, whereas late mortality is related to multiple organ failure.

CONCLUSION

Early recognition and treatment can lower mortality from necrotizing soft tissue infection. Prompt operative debridement, broad-spectrum antimicrobials, and physiologic support are important components of treatment.

Gastrointestinal surgery and pregnancy

Gastrointestinal disorders during pregnancy that require surgery often mimic the symptoms and signs of conditions that do not require surgery. Anatomic and physiologic changes of pregnancy can alter the usual clinical presentation of gastrointestinal disorders that require surgery. These alterations can be a challenge to diagnosis. Prompt treatment is critical to successful management. Most elective and urgent operations can be performed during pregnancy with minimal maternal and fetal risk. The condition of the mother should always take priority because proper treatment of the mother usually benefits the fetus as well.

Hypoxia increases nitric oxide concentrations that are not completely inhibited by L-NMMA

INTRODUCTION

Recent investigations have demonstrated a wealth of knowledge about the biology of nitric oxide (NO) and the synthases (NOS) that generate it, under both physiologic and pathophysiologic conditions. In this study, we investigated the generation of NO under conditions of hypoxia in the absence of confounding functions such as blood loss or hypovolemia.

METHODS

Rats were subjected to either 30 or 60 min of hypoxia and sacrificed immediately or after 1 or 24 h of recuperation. Splenocyte proliferative ability and NO concentrations were determined in whole splenocytes and purified T-cell populations, with and without the use of 20 mg/kg L-NMMA, a potent NOS inhibitor. RT-PCR was performed to determine the presence or absence of inducible NOS transcription after hypoxia and hypoxia followed by reoxygenation with and without L-NMMA.

RESULTS

Hypoxia followed by reoxygenation stimulated NO production in whole splenocytes, which correlated with a decrease in splenocyte proliferation. T-cell stimulation and NO production were not upregulated under these conditions. Additionally, NO generation occurred following hypoxia, even in the presence of L-NMMA.

CONCLUSION

These results demonstrate that NO production after hypoxia may be due to an alternate, O2-independent pathway. Further investigations into the generation of NO through alternate pathways may identify treatments for hypoxia-related injury.

Delayed operative intervention in the management of traumatic descending thoracic aortic rupture

BACKGROUND

Outcomes may be improved by purposefully delaying surgical intervention of the traumatically ruptured descending thoracic aorta.

METHODS

Fifty-seven patient records identified through the Trauma Registry of a level 1 trauma center between January 1993 and April 2002 were retrospectively analyzed between groups who underwent "clamp-and-sew" versus partial left heart bypass repair techniques and between emergent versus delayed repair.

RESULTS

Thirty-two (56%) of 57 patients were male. The mean age among survivors and nonsurvivors was 41 +/- 18 (range 13 to 70) and 52 +/- 23 (range 18 to 92; p = 0.04) years, and Injury Severity Score was 31 +/- 13 (range 17 to 75) and 40 +/- 16 (range 16 to 75; p = 0.04) points, respectively. Thirty-one (54%) underwent surgical intervention, 20 (35%) died during their initial resuscitation, and 6 (11%) were managed nonoperatively. Seventeen (55%) were repaired using partial left heart bypass and 14 (45%) using the clamp technique. Twenty-one (68%) had emergent repair and 10 (32%) had delayed repair. The rates of paraplegia, renal failure, and mortality were 12% (2 of 17), 0%, and 24% (4 of 17) in the bypass group, 0% (p = 0.29), 0%, and 36% (5 of 14, p = 0.36) in the clamp group, 9.5% (2 of 21), 0%, and 38% (8 of 21) in the emergent group (<24 hours after admission), and 0% (p = 0.45), 0%, and 10% (1 of 10, p = 0.12) in the delayed group (>24 hours after admission), respectively. Mean clamp times for the bypass and clamp groups were 44 +/- 18 (21 to 90) and 30 +/- 10 (14 to 52) minutes, respectively (p = 0.02). Overall operative mortality was 29% (9 of 31).

CONCLUSIONS

Purposefully delaying surgical intervention in selected cases of descending thoracic aortic rupture and using the clamp technique does not increase mortality or morbidity over immediate operation and use of partial left hear bypass.

Allopurinol protects enterocytes from hypoxia-induced apoptosis in vivo

BACKGROUND

Reactive oxygen species can cause apoptosis and may be involved in hypoxic injury to the small bowel. Xanthine oxidase (XO) has been implicated in reactive oxygen species production. We hypothesized that administration of allopurinol would protect rat enterocytes from hypoxia-induced apoptosis.

METHODS

Twenty-four Sprague-Dawley rats (weight, 250-300 g) were subjected to 30 minutes of hypoxia (10% Fio(2)), then killed immediately or allowed to recover for an hour in room air (21% Fio(2)). Intraperitoneal allopurinol (50 mg/kg) or an equivalent amount of 0.9% saline was administered 1 hour before hypoxia. Control rats were exposed to 21% Fio(2) under similar conditions. Proximal jejunum was harvested from all animals in both groups and stained to detect apoptotic cells using terminal deoxynucleotidyl transferase-mediated biotinylated deoxynucleotide end labeling. In addition, sections of proximal jejunum were removed and the mucosal membrane was removed and flash frozen in liquid nitrogen for DNA fragmentation gel.

RESULTS

Intraperitoneal administration of allopurinol significantly reduced the percentage of apoptotic villi in the proximal jejunum compared with those animals receiving saline (11 +/- 7 vs. 25 +/- 12 in the hypoxia no recovery group, 41 +/- 14 vs. 67 +/- 8 in the hypoxia with recovery group, mean +/- SD, Mann-Whitney test, < 0.05). Intestinal XO activity was also significantly reduced in the animals receiving allopurinol compared with those receiving saline (6.8 +/- 3.12 vs. 19.1 +/- 4.56 mU/mL/g wet tissue in the hypoxia no recovery group, 0.86 +/- 0.33 vs. 11.5 +/- 7.13 mU/mL/g wet tissue in the hypoxia with recovery group, mean +/- SD, Mann-Whitney test, < 0.05).

CONCLUSION

Inhibition of XO appears to protect rat enterocytes from hypoxia-induced apoptosis in vivo.

Withholding/Withdrawal of Life Support in Trauma Patients: Is There an Age Bias?

Our objective was to examine patterns of withholding/withdrawal (WH/WD) of life support in trauma patients and to determine whether WD/WH of life support is used more frequently in elderly patients. This is a retrospective cohort study of injured elderly (≤65 years) and young patients (<65 years) from 1994 through 1998 treated at a surgical intensive care unit in a community tertiary-care hospital. We studied the cases of 82 patients (30 elderly and 52 young patients) with WH/WD of life support after injury. Our main outcome measures were demographic and clinical characteristics of elderly and young patients undergoing WH/WD of life support after injury with an association between age and WH/WD of life support. Of 102 total trauma patient deaths 82 had WH/WD of life support. This mode was chosen in 52 (80%) patients under the age of 65 and in 30 (81%) patients age 65 or greater. Patients in the younger cohort had a higher mean Injury Severity Score and Abbreviated Injury Score of 5 ( P < 0.05). The elderly cohort had a higher incidence of pre-existing disease (<0.001). Length of stay was similar between the populations. We conclude that the elderly were no more likely to have WH/WD of life support than were younger patients. However, the older patients were less severely injured as measured by Injury Severity Score and percentage with Abbreviated Injury Score head of 5. Other factors such as the presence of pre-existing disease may influence the decision to withhold or withdraw life support to a greater degree than the actual severity of injuries.

Withholding/withdrawal of life support in trauma patients: is there an age bias?

Our objective was to examine patterns of withholding/withdrawal (WH/WD) of life support in trauma patients and to determine whether WD/WH of life support is used more frequently in elderly patients. This is a retrospective cohort study of injured elderly (> or = 65 years) and young patients (< 65 years) from 1994 through 1998 treated at a surgical intensive care unit in a community tertiary-care hospital. We studied the cases of 82 patients (30 elderly and 52 young patients) with WH/WD of life support after injury. Our main outcome measures were demographic and clinical characteristics of elderly and young patients undergoing WH/WD of life support after injury with an association between age and WH/WD of life support. Of 102 total trauma patient deaths 82 had WH/WD of life support. This mode was chosen in 52 (80%) patients under the age of 65 and in 30 (81%) patients age 65 or greater. Patients in the younger cohort had a higher mean Injury Severity Score and Abbreviated Injury Score of 5 (P < 0.05). The elderly cohort had a higher incidence of pre-existing disease (< 0.001). Length of stay was similar between the populations. We conclude that the elderly were no more likely to have WH/WD of life support than were younger patients. However, the older patients were less severely injured as measured by Injury Severity Score and percentage with Abbreviated Injury Score head of 5. Other factors such as the presence of pre-existing disease may influence the decision to withhold or withdraw life support to a greater degree than the actual severity of injuries.

Admitting service influences the outcomes of patients with small bowel obstruction

BACKGROUND

Small bowel obstruction (SBO) is a common problem that often requires operation. We tested the hypotheses that patients admitted to a surgical service have improved outcomes and that these outcomes are related to early operation.

METHODS

Retrospective review of 281 patients with 336 episodes of SBO between 1992 and 1998 was performed. Parametric and nonparametric analysis was used as appropriate.

RESULTS

There were 222 admissions to a surgical service and 114 admissions to a medical service. Patient characteristics were similar between groups. Eighty-seven percent of patients had a previous abdominal or pelvic operation. There were 211 patients (217 admissions) who required operation. Operated patients admitted to the surgical service had a shorter preoperative (2.7 vs 6.3 days, P <.01) and overall length of stay (LOS) (17.9 vs 22.8 days, P <.0001). There was no difference in time to resumption of diet between groups. The number of previous admissions or operations did not affect the need for operative intervention. Unoperated patients admitted to a medical service had a shorter time to resumption of diet (3.1 vs 4.3 days) and LOS (4.8 vs 7.2 days, both P <.05) than the surgical service group. Operative mortality was 3.4%. The likelihood of developing a complication was related to the occurrence of an enterotomy (n = 21, odds ratio = 2.69; 95% confidence interval [CI]: 1.1-6.7, P =.014) or the need for bowel resection (odds ratio = 1.97; 95% CI: 1.2-3.5, P =.02). The occurrence of a complication resulted in a 46% increase in LOS (P <.0001). Patients operated on within 24 hours of admission had a decreased LOS (P <.05) and mortality, with no difference in the occurrence of postoperative complications.

CONCLUSIONS

Patients with SBO who require operation benefit from a shorter time to operation and reduced LOS when admitted to a surgical service. Early operation is associated with a reduction in mortality, and avoidance of enterotomy decreases the risk of complications.

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.

Geriatric trauma hospitalization in the United States

The objective of this study was to characterize elderly trauma hospitalizations nationwide. Elderly Medicare beneficiaries hospitalized in 1989, with trauma as a primary or secondary diagnosis, were studied cross-sectionally. Descriptive analyses and primary mortality rates among different levels of trauma center designation were provided. Estimated relative risks, chi-square tests of association, and multivariate logistic regression were performed. There were 577,193 geriatric trauma patients admitted to 5227 short-stay U.S. hospitals. Level one trauma centers constituted less than 4% of hospitals, but admitted 7.5% of patients, including disproportionate numbers of blacks, males, and patients with more severe primary injury diagnoses. Risk of inpatient death increased with age, male gender, black race, and severity of injury. Level one trauma center patients displayed a 1.49 greater risk for inpatient death even after controlling for confounding variables in a multivariate model. This population-based study provides a detailed national picture of the elderly trauma hospitalization experience, contrasting profiles and outcomes between hospitals with and without designated trauma centers. Although demonstrating higher inpatient mortality rates, Level one trauma centers admit a decidedly different patient population than other hospitals, which is disproportionately younger, black and male and includes the most severely injured geriatric patients. Additional confounding factors should be explored.

Prospective randomized trials affect the outcomes of intraabdominal infection

OBJECTIVE

To compare the characteristics and outcomes of patients with intraabdominal infections enrolled in prospective randomized trials (PRTs) with those of a cohort of patients not enrolled in a trial.

SUMMARY BACKGROUND DATA

Prospective randomized trials are the gold standard for the evaluation of new treatments. Patients are screened using rigorous eligibility criteria and sometimes are excluded from PRTs because of associated medical conditions or more severe illness. However, the effect that the exclusion of these patients has on the applicability of clinical trial outcomes has not been defined.

METHODS

One hundred sixty-eight adults with intraabdominal infection were treated at a single institution during 7 years. Fifty-three patients were enrolled in four PRTs comparing various antibiotic regimens for treatment; 115 were not enrolled. Patient characteristics and outcomes of these two groups were compared.

RESULTS

Patients with infections from appendicitis (n = 68) had a low severity of illness and similar outcomes in both groups. These patients and those for whom a concurrent PRT was unavailable were excluded from subsequent analysis. Eighty-eight patients (42 PRT, 46 not enrolled) with serious infection remained for analysis. Patients enrolled in PRTs were younger, had less severe illness, had a decreased length of stay, a lower incidence of antibiotic resistance, and less frequent extraabdominal infections than those not enrolled in a trial. Patients enrolled in PRTs were more likely to be cured and were less likely to die. Logistic regression analysis demonstrated that cure was associated with a lower initial severity of illness, absence of antibiotic resistance, and participation in a PRT.

CONCLUSIONS

Patients with intraabdominal infection enrolled in PRTs have an increased likelihood of cure and survival. This is due in part to a lower incidence of antibiotic resistance, which may reflect improved drug selection. Patients not enrolled in PRTs are at greater risk for treatment failure and death because of concomitant illness. Outcomes from PRTs may not be applicable to all patients with intraabdominal infections.