Effect of an education program aimed at reducing the occurrence of ventilator-associated pneumonia

OBJECTIVE

The purpose of the study was to determine whether an education initiative could decrease the hospital rate of ventilator-associated pneumonia.

DESIGN

Pre- and postintervention observational study.

SETTING

Five intensive care units in Barnes-Jewish Hospital, an urban teaching hospital.

PATIENTS

Patients requiring mechanical ventilation who developed ventilator-associated pneumonia between October 1, 1999, and September 30, 2001.

INTERVENTIONS

An education program directed toward respiratory care practitioners and intensive care unit nurses was developed by a multidisciplinary task force to highlight correct practices for the prevention of ventilator-associated pneumonia. The program consisted of a ten-page self-study module on risk factors and practice modifications involved in ventilator-associated pneumonia, inservices at staff meetings, and formal didactic lectures. Each participant was required to take a preintervention test before the study module and identical postintervention tests following completion of the study module. Fact sheets and posters reinforcing the information in the study module were also posted throughout the intensive care units and the Department of Respiratory Care Services.

MEASUREMENTS AND MAIN RESULTS

One hundred ninety-one episodes of ventilator-associated pneumonia occurred in 15,094 ventilator days (12.6 per 1,000 ventilator days) in the 12 months before the intervention. Following implementation of the education module, the rate of ventilator-associated pneumonia decreased to 81 episodes in 14,171 ventilator days (5.7 per 1,000 ventilator days), a decrease of 57.6% (p <.001). The estimated cost savings secondary to the decreased rate of ventilator-associated pneumonia for the 12 months following the intervention were between $425,606 and $4.05 million.

CONCLUSIONS

A focused education intervention can dramatically decrease the incidence of ventilator-associated pneumonia. Education programs should be more widely employed for infection control in the intensive care unit setting and can lead to substantial decreases in cost and patient morbidity attributed to hospital-acquired infections.

Inhibition of intestinal epithelial apoptosis and survival in a murine model of pneumonia-induced sepsis

CONTEXT

Increased intestinal epithelial apoptosis is present in both human autopsy studies and animal models of sepsis. Whether altering gut apoptosis decreases mortality in sepsis induced by pathogenic bacteria outside the gut is unknown.

OBJECTIVE

To determine if decreasing levels of intestinal cell death improves survival in a murine model of Pseudomonas aeruginosa pneumonia-induced sepsis.

DESIGN AND MATERIALS

Prospective study in which transgenic mice that overexpress the antiapoptotic protein Bcl-2 in their intestinal epithelium (n = 25) and control littermates (n = 26) were subjected to intratracheal injection of P aeruginosa.

MAIN OUTCOME MEASURES

Survival at 7 postoperative days, compared between the 2 groups. Secondary outcomes included quantification of gut epithelial apoptosis.

RESULTS

Survival in transgenic mice that overexpress Bcl-2 in the intestinal epithelium was 40% (10/25) compared with 4% (1/26) in control littermates 7 days after intratracheal injection of P aeruginosa (P =.001), with differences in survival noted within 24 hours of surgery. Overexpression of Bcl-2 was associated with a decrease in gut epithelial apoptosis demonstrated by active caspase 3 staining, the terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling assay, and hematoxylin-eosin staining.

CONCLUSIONS

In this murine model, inhibiting gut epithelial apoptosis by overexpression of Bcl-2 was associated with a survival advantage in P aeruginosa pneumonia-induced sepsis. These results suggest that intestinal epithelial apoptosis may play a role in sepsis-related mortality.

Overexpression of Bcl-2 in the intestinal epithelium improves survival in septic mice

OBJECTIVES

The aim of this study was to determine whether decreasing intestinal epithelial apoptosis in sepsis would alter mortality rates. The roles of the antiapoptotic protein Bcl-2 and the "executioner" protease caspase-3 in sepsis-induced gut cell death also were evaluated.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Animal laboratory in an academic medical center.

INTERVENTIONS

Transgenic mice that overexpress Bcl-2 throughout the small intestinal epithelium (n = 23) and littermate controls (n = 27) were subjected to cecal ligation and puncture (CLP) and followed for 8 days to assess survival. A second group of transgenic (n = 15) and littermate animals (n = 15) were subjected to CLP and were killed between 16 and 48 hrs postoperatively to assess for intestinal apoptosis and active caspase-3 staining.

MEASUREMENTS AND MAIN RESULTS

Survival of transgenic animals was 83% 8 days after CLP compared with 44% for littermate controls (p < .005). Survival curves between the two groups of animals began diverging within 24 hrs. Overexpression of Bcl-2 was associated with a significant decrease in apoptosis between 16 and 24 hrs post-CLP (p < .05) as well as decreased staining for active caspase-3.

CONCLUSIONS

Decreasing intestinal epithelial cell death via overexpression of Bcl-2 improves survival in septic mice. The gut may play a central role in the pathophysiology of sepsis.

Effect of an education program on decreasing catheter-related bloodstream infections in the surgical intensive care unit

OBJECTIVE

The purpose of the study was to determine whether an education initiative aimed at improving central venous catheter insertion and care could decrease the rate of primary bloodstream infections.

DESIGN

Pre- and postintervention observational study.

SETTING

Eighteen-bed surgical/burn/trauma intensive care unit (ICU) in an urban teaching hospital.

PATIENTS

A total of 4,283 patients were admitted to the ICU between January 1, 1998, and December 31, 2000.

INTERVENTIONS

A program primarily directed toward registered nurses was developed by a multidisciplinary task force to highlight correct practice for central venous catheter insertion and maintenance. The program consisted of a 10-page self-study module on risk factors and practice modifications involved in catheter-related infections as well as a verbal in-service at staff meetings. Each participant was required to take a pretest before taking the study module and an identical test after its completion. Fact sheets and posters reinforcing the information in the study module were also posted throughout the ICU.

MEASUREMENTS AND MAIN RESULTS

Seventy-four primary bloodstream infections occurred in 6874 catheter days (10.8 per 1000 catheter days) in the 18 months before the intervention. After the implementation of the education module, the number of primary bloodstream infections fell to 26 in 7044 catheter days (3.7 per 1000 catheter days), a decrease of 66% (p < .0001). The estimated cost savings secondary to the decreased infection rate for the 18 months after the intervention was between $185,000 and $2.808 million.

CONCLUSIONS

A focused intervention primarily directed at the ICU nursing staff can lead to a dramatic decrease in the incidence of primary bloodstream infections. Educational programs may lead to a substantial decrease in cost, morbidity, and mortality attributable to central venous catheterization.

Hepatocellular carcinoma in a patient with focal nodular hyperplasia

BACKGROUND

Focal nodular hyperplasia is an uncommon liver tumour that typically requires no therapeutic intervention.

CASE OUTLINE

A 43-year-old woman with a 20-year history of oral contraceptive use presented with symptomatic bilateral liver masses. Biopsy revealed hepatocellular carcinoma in the right hemiliver and focal nodular hyperplasia in the left hemiliver. At operation,t he patient was noted to have multiple liver nodules bilaterally, and all intraoperative biopsies were consistent with focal nodular hyperplasia including a biopsy taken from the region that demonstrated carcinoma preoperatively. Because of the earlier biopsy results and the patient's preoperative symptoms, a right hemihepatectomy was performed. Final pathology revealed hepatocellular carcinoma directly adjacent to an area of focal nodular hyperplasia, as well as multiple other areas of hyperplastic liver tumour.

DISCUSSION

Although focal nodular hyperplasia is believed to be benign, few studies have followed patients with this tumour beyond three years. Longer-term follow-up studies are needed to determine the natural history of focal nodular hyperplasia, potentially focussing on a subset of patients with either diffuse tumours or prolonged oral contraceptive use.

Renal transplantation following previous heart, liver, and lung transplantation: an 8-year single-center experience

BACKGROUND

Long-term follow-up of heart, liver, and lung transplantation has led to an increased recognition of secondary end-stage renal failure (ESRF) in transplant recipients. This study examines our center's experience with renal transplantation following previous solid organ transplantation.

METHODS

From January 1, 1992, to September 30, 1999, our center performed 18 renal transplants in previous solid organ recipients. During the same period, 815 total renal transplants were performed. One- and 3-year graft and patient survival, recipient demographics, donor type, and reason for transplantation were compared between these groups.

RESULTS

Of the 18 recipients, 7 had prior heart transplants, 4 had prior liver transplants, and 7 had prior lung transplants. Cyclosporine toxicity contributed to renal failure in 17 (94.4%) of the patients-either as a sole factor (11 patients) or in combination with hypertension, renal artery stenosis, or tacrolimus toxicity (6 patients). Kaplan-Meier 1- and 3-year patient survival was 82.9% and 73.7%, compared with 95.5% and 90.7% in all renal transplant recipients. No surviving patient has suffered renal allograft loss. Mean current creatinine level is 1.4 mg/dL.

CONCLUSIONS

Renal transplantation is an excellent therapy for ESRF following prior solid organ transplantation. One and 3-year patient and graft survival demonstrate the utility of renal transplantation in this patient population.

Unusual presentations of nonmycotic hepatic artery pseudoaneurysms after liver transplantation

The clinical presentation and causes of hepatic artery pseudoaneurysm vary widely in the postoperative liver transplant recipient, although infection is the most common cause. Although uncommon, hepatic artery complications continue to be an important source of morbidity in liver transplant recipients. Thrombosis, stenosis, and pseudoaneurysm formation are the most common posttransplantation arterial complications. Pseudoaneurysms are most commonly mycotic in origin. Prompt recognition of hepatic artery pseudoaneurysms with aggressive intervention (both surgical and angiographic) may decrease the morbidity associated with this rare clinical entity. The records of 263 consecutive patients who underwent orthotopic liver transplantation between 1991 and 1996 were reviewed retrospectively and assessed for hepatic artery complications. Two patients (0.7%) developed hepatic artery pseudoaneurysm, neither associated with infection. Both patients required operative repair and are doing well without vascular complications at a mean follow-up of 22.5 months. The clinical presentation and causes of hepatic artery pseudoaneurysm vary widely in the postoperative liver transplant recipient. Prompt recognition of hepatic artery pseudoaneurysms with aggressive intervention (both surgical and angiographic) may decrease the morbidity associated with this rare clinical entity.

Bcl-2 inhibits ischemia-reperfusion-induced apoptosis in the intestinal epithelium of transgenic mice

Little is known about the effects of ischemia-reperfusion on the inductive, commitment, or execution phases of apoptosis. We have created a genetically defined model to study the response of small intestinal epithelial cells to ischemia-reperfusion injury as a function of their proliferative status and differentiation. Occlusion of the superior mesenteric artery for 20 min in adult FVB/N or C57BL/6 mice results in the appearance of TUNEL-positive apoptotic cells in the jejunal epithelium within 4 h, with a maximum response occurring at 24 h. Stimulation of apoptosis is greater in postmitotic, differentiated epithelial cells located in the upper portions of villi compared with undifferentiated, proliferating cells in the crypts of Lieberkühn (7-fold vs. 2-fold relative to sham-operated controls). Comparisons of p53(+/+) and p53(-/-) mice established that the apoptosis is p53 independent. To further characterize this response, we generated FVB/N transgenic mice that express human Bcl-2 in epithelial cells distributed from the base of crypts to the tips of their associated villi. The fivefold elevation in steady-state Bcl-2 concentration is not accompanied by detectable changes in the levels or cellular distributions of the related anti-apoptotic regulator Bcl-xL or of the proapoptotic regulators Bax and Bak and does not produce detectable effects on basal proliferation, differentiation, or death programs. The apoptotic response to ischemia-reperfusion is reduced twofold in the crypts and villi of transgenic mice compared with their normal littermates. These results suggest that both undifferentiated and differentiated cells undergo a commitment phase that is sensitive to Bcl-2. Forced expression of Bcl-2 also suppressed the p53-dependent death that occurs in proliferating crypt epithelial cells following gamma-irradiation. Thus suppressibility by Bcl-2 operationally defines a common feature of the apoptosis induced in the crypt epithelium by these two stimuli.

Surgery of the small intestine

This article reviews both clinical and scientific advances in surgery of the small intestine that have been reported in the last year. The management of both pediatric and adult intussusception is considered. Multiple studies on the evolving role of ileal pouch-anal anastomosis are assessed. The treatment and epidemiology of a wide variety of intestinal neoplasms are reviewed. Advances in small bowel transplantation are also reported. The cause of small bowel obstruction is considered as well as new strategies to prevent adhesion formation. Finally, a number of diverse topics relating to intestinal surgery, including new data on laparoscopic surgery, treatment of enterocutaneous fistulas, reconstruction after total gastrectomy, intestinal transit after ileocecal segment transposition, and ischemia/reperfusion and anastomotic healing, are reviewed.

Bi-transgenic mice reveal that K-rasVal12 augments a p53-independent apoptosis when small intestinal villus enterocytes reenter the cell cycle

Studies in cell culture systems have indicated that oncogenic forms of Ras can affect apoptosis. Activating mutations of Ras occur in approximately 30% of all human tumors and 50% of colorectal carcinomas. Since these mutations appear at early or intermediate stages in multistep journeys to neoplasia, an effect on apoptosis may help determine whether initiated cells progress towards a more neoplastic state. We have tested the effects of K-rasVal12 on apoptosis in transgenic mice. A lineage-specific promoter was used to direct expression of human K-rasVal12, with or without wild-type (wt) or mutant SV-40 T antigens (TAg), in postmitotic villus enterocytes, the principal cell type of the small intestinal epithelium. Enterocytes can be induced to reenter the cell cycle by TAgWt. Reentry is dependent upon the ability of TAg to bind pRB and is associated with a p53-independent apoptosis. Analyses of K-rasVal12 x TAgWt bi-transgenic animals indicated that K-rasVal12 can enhance this apoptosis threefold but only in cycling cells; increased apoptosis does not occur when K-rasVal12 is expressed alone or with a TAg containing Glu107,108two head right arrow Lys107, 108 substitutions that block its ability to bind pRB. Analysis of bi-transgenic K-rasVal12 x TAgWt mice homozygous for wild-type or null p53 alleles established that the enhancement of apoptosis occurs through a p53-independent mechanism, is not attributable to augmented proliferation or to an increase in abortive cell cycle reentry (compared to TAgWt mice), and is not associated with detectable changes in the crypt-villus patterns of expression of apoptotic regulators (Bcl-2, Bcl-xL, Bak, and Bax) or mediators of epithelial cell-matrix interactions and survival (e.g., alpha5beta1 integrin and its ligand, fibronectin). Coexpression of K-rasVal12 and TAgWt produces dysplasia. The K-rasVal12-augmented apoptosis is unrelated to this dysplasia; enhanced apoptosis is also observed in cycling nondysplastic enterocytes that produce K-rasVal12 and a TAg with a COOH-terminal truncation. The dysplastic epithelium of K-rasVal12 x TAgWt mice does not develop neoplasms. Our results are consistent with this finding: (a) When expressed in initiated enterocytes with a proliferative abnormality, K-rasVal12 facilitates progression to a dysplastic phenotype; (b) by diminishing cell survival on the villus, the oncoprotein may impede further progression; and (c) additional mutations may be needed to suppress this proapoptotic response to K-rasVal12.

gamma-Ray-induced apoptosis in transgenic mice with proliferative abnormalities in their intestinal epithelium: re-entry of villus enterocytes into the cell cycle does not affect their radioresistance but enhances the radiosensitivity of the crypt by inducing p53

The radiosensitivity of proliferating crypt epithelial cells makes the gut a major limiting factor in the use of radiotherapy for treatment of abdominal cancers. As post-mitotic epithelial cells migrate from mouse small intestinal crypts to the base of adjacent villi, they rapidly lose their ability to undergo apoptosis in response to ionizing irradiation (IR). To determine whether this radioresistance reflects withdrawal from the cell cycle, we used a lineage-specific promoter to direct expression of wild type Simian virus 40 T antigen (SV40 TAg(Wt)) to villus, but not crypt, enterocytes in FVB/N transgenic mice. SV40 TAg(Wt) induced, pRB-dependent, re-entry into the cell cycle is not associated with the acquisition of IR-stimulated apoptosis 4 h or 24 h after 6 Gy or 12 Gy of gamma-irradiation. Co-expression of SV40 TAg(Wt) and K-ras(val12) produces dysplasia in cycling villus enterocytes but no shift towards apoptotic responsiveness to IR. These findings suggest that the radioresistance of villus enterocytes is not simply due to their cell cycle arrest and may be a reflection of their microenvironment. Remarkably, reentry of villus enterocytes to the cell cycle increases the radiosensitivity of the crypt epithelium without changing Bcl-2, Bcl-xL, Bak, or Bax expression. This effect is only manifest after IR and, based upon results obtained with mutant SV40 TAgs, depends upon reaching a critical level of proliferation in villus enterocytes. Like the normal crypt response to IR, the villus-derived enhancement of IR-stimulated crypt apoptosis is associated with an induction of p53 and Raf-1, and is dependent upon p53. Unlike the normal crypt response to IR, the p53 induction involves cells distributed throughout the crypt and the apoptotic response is not confined to the lower half of the crypt. These results indicate that signals initiated by cycling enterocytes can be transmitted to the crypt epithelium to induce p53 and influence their IR-induced apoptosis. Understanding the underlying signaling pathways may provide clues about how to modify a normal crypt's radiosensitivity for therapeutic benefit.

Use of normal and transgenic mice to examine the relationship between terminal differentiation of intestinal epithelial cells and accumulation of their cell cycle regulators

A spatially well organized continuum of proliferation, differentiation, and death is displayed along crypt-villus units in the adult mouse small intestine. This continuum provides an opportunity to examine in vivo the mechanisms by which proliferative status changes as a function of cellular differentiation. Immunohistochemical studies of normal FVB/N mice revealed that as epithelial cells complete their terminal differentiation during a 48-72-h migration up villi, there is a marked and rapid fall in the levels of two important regulators of the G1/S transition, cyclin D1 and cyclin-dependent kinase (cdk) 2. However, cellular levels of their partners, cdk4 and cyclin E, remain unchanged as does the level of pRB. Adult FVB/N transgenic mice were studied that contained an intestinal fatty acid binding protein gene promoter (Fabpi) linked to wild type Simian virus 40 large T antigen (SV40 TAgWt) or a mutant TAg with Lys for Glu substitutions at residues 107 and 108 (SV40 TAgK107/8) that fails to bind pRB and related pocket proteins. Both transgenes are expressed only in villus enterocytes. SV40 TAgWt causes these terminally differentiated cells to re-enter the cycle. Re-entry is accompanied by a reduction in un/hypophosphorylated pRB, an induction of cyclin D1 and cdk2, but no change in cdk4, cyclin E, or E2F-1. In contrast, SV40 TAgK107/8 fails to induce re-entry and does not produce changes in un/hypophosphorylated pRB, cyclin D1, or cdk2 accumulation. These results suggest that un/hypophosphorylated pRB is an important mediator of the cell cycle arrest that normally occurs as enterocytes exit the crypt and complete their differentiation. Fabpi-directed expression of E2F-1 does not cause villus enterocytes to return to the cell cycle, alter their suppression of cyclin D1 or cdk2, or affect their state of differentiation, emphasizing the insensitivity of these cells to the effects of E2F-1. Analyses of p53(-/-) and p53(+/+) mice containing Fabpi-SV40 TAgWt and Fabpi-SV40 TAgK107/8 established that the proliferation induced by SV40 TAgWt does not require p53 and is associated with increased (p53-independent) apoptosis. The presence of cyclin E and cdk4 in differentiating villus enterocytes emphasizes that these cells retain part of their proliferative heritage expressed 24-72 h earlier in the crypt. The data suggest that down-regulation of cdk2 and/or cyclin D1 expression may be important for control of proliferative status and/or execution of terminal differentiation.

Expression of wild-type and mutant simian virus 40 large tumor antigens in villus-associated enterocytes of transgenic mice

The four principal gut epithelial cell lineages undergo continuous and rapid renewal during a geographically well-organized migration along the crypt-to-villus axis. The molecules that regulate their proliferation and differentiation programs are largely unknown. The large tumor antigen (TAg) of wild-type (wt) simian virus 40 (SV40) and its mutant derivatives represent tools for describing the contributions of regulators of the cell cycle to the proliferative state of each lineage. Expression of SV40 TAgwt in postmitotic, villus-associated enterocytes of transgenic mice causes them to reenter the cell cycle without an apparent effect on their state of differentiation. When human KRAS with a Val-12 substitution ([Val12]KRAS) is coexpressed with SV40 TAgwt in villus enterocytes of bitransgenic animals, the two oncoproteins cooperate to produce dedifferentiation (dysplasia). SV40 mutant d11137 expresses a TAg that is unable to complex with p53 but retains N-terminal transforming functions, including the ability to complex pRB, p107, and p300. When SV40 TAgd11137 is expressed in villus enterocytes, they reenter into the cell cycle. However, coexpression of SV40 TAgd11137 and [Val12]KRAS does not produce dysplastic changes. Thus, the N-terminal 121 residues of TAg are sufficient to perturb the proliferative state of the enterocyte but not to produce detectable changes in the state of differentiation when coexpressed with [Val12]KRAS.