Sepsis Syndrome, the Adult Respiratory Distress Syndrome, and Nosocomial Pneumonia

Ferret acute lung injury model induced by repeated nebulized lipopolysaccharide administration

Inflammatory lung diseases affect millions of people worldwide. These diseases are caused by a number of factors such as pneumonia, sepsis, trauma, and inhalation of toxins. Pulmonary function testing (PFT) is a valuable functional methodology for better understanding mechanisms of lung disease, measuring disease progression, clinical diagnosis, and evaluating therapeutic interventions. Animal models of inflammatory lung diseases are needed that accurately recapitulate disease manifestations observed in human patients and provide an accurate prediction of clinical outcomes using clinically relevant pulmonary disease parameters. In this study, we evaluated a ferret lung inflammation model that closely represents multiple clinical manifestations of acute lung inflammation and injury observed in human patients. Lipopolysaccharide (LPS) from Pseudomonas aeruginosa was nebulized into ferrets for 7 repeated daily doses. Repeated exposure to nebulized LPS resulted in a restrictive pulmonary injury characterized using Buxco forced maneuver PFT system custom developed for ferrets. This is the first study to report repeated forced maneuver PFT in ferrets, establishing lung function measurements pre- and post-injury in live animals. Bronchoalveolar lavage and histological analysis confirmed that LPS exposure elicited pulmonary neutrophilic inflammation and structural damage to the alveoli. We believe this ferret model of lung inflammation, with clinically relevant disease manifestations and parameters for functional evaluation, is a useful pre-clinical model for understanding human inflammatory lung disease and for the evaluation of potential therapies.

The prevalence of complications of pneumonia among adults admitted to a tertiary care center in Riyadh from 2010-2017

BACKGROUND

Pneumonia, the commonest lower respiratory tract infection, can result in respiratory and non-respiratory complications. Few studies have reported on the prevalence of many complications.

OBJECTIVES

Identify the prevalence of 18 complications of pneumonia and compare complication rates by age group and type of pneu.monia. Identify most prevalent comorbidities, the effect of the number of comorbidities on the presence of complications, and the association between specific comorbidities and specific complications.

DESIGN

Retrospective, cross-sectional prevalence study.

SETTING

Tertiary care center in Riyadh.

PATIENTS AND METHODS

The target population were patients aged 17 years and older, of different nationalities and both genders, diagnosed with pneumonia during the period of 2010 to 2017. Selection was by stratified sampling by year of admission.

MAIN OUTCOME MEASURES

Complications of pneumonia.

SAMPLE SIZE

800.

RESULTS

Complications were observed in 427 patients (53.4%). The complications were respiratory in 258 patients (32%), sepsis and septic shock in 186 (23%), cardiac in 125 (16%), neurological in 5 (0.6%), and cholestatic jaundice in 2 (0.3%). Pleural effusion was the commonest complication, observed in 230 patients. There was a significant difference (P less than .001) between the complication rates in older patients compared to younger (60% as compared to 41%). For the type of pneumonia, there was a significant difference (P less than .001) between community-acquired pneumonia and hospital-acquired pneumonia in the presence of complications (OR=2.41, 95% CI for OR=1.66, 3.49). The number of comorbidities was significantly associated with the presence of complications (P=.001) for those with multiple comorbidities (46% for patients with no comorbid illnesses versus 68% in patients with three or more comorbidities).

CONCLUSION

These results suggest that Saudi Arabia needs to establish better prevention and intervention programs, especially for the high-risk groups identified in this study: older patients, patients with hospital-acquired pneumonia and patients with two or more comorbidities.

LIMITATIONS

Retrospective design and single-centered.

CONFLICT OF INTEREST

None.

IFN-β Improves Sepsis-related Alveolar Macrophage Dysfunction and Postseptic Acute Respiratory Distress Syndrome-related Mortality

IFN-β is reported to improve survival in patients with acute respiratory distress syndrome (ARDS), possibly by preventing sepsis-induced immunosuppression, but its therapeutic nature in ARDS pathogenesis is poorly understood. We investigated the therapeutic effects of IFN-β for postseptic ARDS to better understand its pathogenesis in mice. Postseptic ARDS was reproduced in mice by cecal ligation and puncture to induce sepsis, followed 4 days later by intratracheal instillation of Pseudomonas aeruginosa to cause pneumonia with or without subcutaneous administration of IFN-β 1 day earlier. Sepsis induced prolonged increases in alveolar TNF-α and IL-10 concentrations and innate immune reprogramming; specifically, it reduced alveolar macrophage (AM) phagocytosis and KC (CXCL1) secretion. Ex vivo AM exposure to TNF-α or IL-10 duplicated cytokine release impairment. Compared with sepsis or pneumonia alone, pneumonia after sepsis was associated with blunted alveolar KC responses and reduced neutrophil recruitment into alveoli despite increased neutrophil burden in lungs (i.e., "incomplete alveolar neutrophil recruitment"), reduced bacterial clearance, increased lung injury, and markedly increased mortality. Importantly, IFN-β reversed the TNF-α/IL-10-mediated impairment of AM cytokine secretion in vitro, restored alveolar innate immune responsiveness in vivo, improved alveolar neutrophil recruitment and bacterial clearance, and consequently reduced the odds ratio for 7-day mortality by 85% (odds ratio, 0.15; 95% confidence interval, 0.03-0.82; P = 0.045). This mouse model of sequential sepsis → pneumonia infection revealed incomplete alveolar neutrophil recruitment as a novel pathogenic mechanism for postseptic ARDS, and systemic IFN-β improved survival by restoring the impaired function of AMs, mainly by recruiting neutrophils to alveoli.

Difficulties in modelling ARDS (2017 Grover Conference Series)

Fifty years after the first description of acute respiratory distress syndrome (ARDS), none of the many positive drug studies in animal models have been confirmed in clinical trials and translated into clinical practice. This bleak outcome of so many animal experiments shows how difficult it is to model ARDS. Lungs from patients are characterized by hyperinflammation, permeability edema, and hypoxemia; accordingly, this is what most models aim to reproduce. However, in animal models it is very easy to cause inflammation in the lungs, but difficult to cause hypoxemia. Often - and not unlike in patients - models with hypoxemia are accompanied by cardiovascular failure that necessitates fluid support and ventilation, raising the question as to the role of intensive care measures in models of ARDS. In our opinion, there are two major arguments in favor of modelling intensive care medicine in models of ARDS: (1) preventing death from shock; and (2) modelling ventilation and other ICU measures as a second hit. The preferable predictive endpoints in any model of ARDS remain unclear. At present, the best recommendation is to use endpoints that can be compared across studies (i.e. PaO₂/FiO₂ ratio, compliance, wet-to-dry weight ratio) rather than percentage data. Another important and often overlooked issue is the fact that the thermoneutral environmental temperatures for mice and rats are 30℃ and 28℃, respectively; thus, at room temperature (20-22℃) they suffer from cold stress with the associated significant metabolic changes. While, by definition, any model is an abstraction, we suggest that clinically relevant models of ARDS will have to closer recapitulate important properties of the disease while taking into account species-specific confounders.

The biology of natural killer cells during sepsis

Natural killer (NK) cells are large granular lymphocytes largely recognized for their importance in tumour surveillance and the host response to viral infections. However, as the major innate lymphocyte population, NK cells also coordinate early responses to bacterial infections by amplifying the antimicrobial functions of myeloid cells, especially macrophages, by production of interferon-γ (IFN-γ). Alternatively, excessive NK cell activation and IFN-γ production can amplify the systemic inflammatory response during sepsis resulting in increased physiological dysfunction and organ injury. Our understanding of NK cell biology during bacterial infections and sepsis is mostly derived from studies performed in mice. Human studies have demonstrated a correlation between altered NK cell functions and outcomes during sepsis. However, mechanistic understanding of NK cell function during human sepsis is limited. In this review, we will review the current understanding of NK cell biology during sepsis and discuss the challenges associated with modulating NK cell function during sepsis for therapeutic benefit.

The Management of Sepsis: A Practical Review

The incidence of the sepsis syndrome has increased dramatically in the last few decades. During this time we have gained new insights into the pathophysiologic mechanisms leading to organ dysfunction in sepsis and the importance of the host-bacterial interactions in mediating many of these processes. This knowledge has led to new therapeutic approaches and the investigation of a number of novel agents. An assessment of these approaches is presented to aid clinicians in the management of patients with severe sepsis. Criteria used to select studies included their relevance to the management of sepsis and their pertinence to clinicians. Appropriate antibiotic selection and volume resuscitation remain the cornerstone of treatment of septic patients. Hydroxyethyl starch solutions have theoretical advantages over crystalloids; there is, however, no data that the type of resuscitation fluid alters outcome. Vasoactive agents are required in patients who remain hemodynamically unstable or have evidence of tissue hypoxia after adequate volume resuscitation. Although dopamine is widely used, dobutamine and norepinephrine are our vasoactive agents of choice. Dopamine has no proven role in oliguric patients, with early dialysis recommended in patients with acute renal failure. The preferred method of renal replacement therapy remains to be determined. Blood products should be used cautiously in patients with disseminated intravascular coagulation. Therapeutic strategies that interfere with the immune system have not been proven to improve the outcome in unselected groups of patients. However, immunomodulation may prove to have a role in select subgroups of patients. Antibiotic therapy and intensive physiological support continues to be the main approach to the management of patients with severe sepsis. Despite the development of numerous novel therapeutic agents, these drugs have not been demonstrated to improve patient outcome.

Antibiotic resistance patterns in medical and surgical patients in a combined medical-surgical intensive care unit

PURPOSE

Studies have found different rates of antimicrobial resistance among patients in medical and surgical intensive care units (ICUs). We studied whether these differences were a function of geography or differences in the patient populations, by comparing resistance rates among bacteria isolated from a combined medical/surgical ICU.

MATERIALS AND METHODS

We retrospectively evaluated the results of bacterial cultures of each patient admitted to the ICU between February 2005 and September 2006. Data collection included patient demographics and culture and sensitivity results. Intensive care unit populations were compared using the Fisher exact test and the Student t test.

RESULTS

One hundred seventy-one medical and 94 surgical patients with positive cultures were studied. Organisms were grouped into 4 classes: Staphylococcus aureus, nonlactose fermenting gram-negative bacilli, Enterococcus species, and gram-negative enteric bacteria. In the 4 classes, no significant difference in antibiotic resistance was found between medical and surgical patients.

CONCLUSION

Reported differences in resistance patterns among bacteria cultured from medical and surgical patients may be due to geographic separation of the ICUs as opposed to differences in the patient characteristics. This study suggests that ICU-specific antibiograms remain a useful tool to guide the choice of antimicrobial therapy, even in medical/surgical ICUs.

Detection of tumor necrosis factor-α and interleukin-6 in exhaled breath condensate of rats with pneumonia due to staphylococcal enterotoxin B

Exhaled breath condensate (EBC) may contain mediators of acute lung injury. The objectives were to determine if EBC could be collected in a mechanically ventilated rat, to measure tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in the EBC after staphylococcal enterotoxin B administration (SEB) and to find out if the concentrations of TNF-α and IL-6 correlated with those in lung lavage. Four hours after SEB instillation, rats were placed on mechanical ventilation and EBC was collected over 90 minutes. Lung lavage was collected and white cell count was determined. TNF-α and IL-6 were measured in the EBC and lavage. EBC was available in a sufficient quantity (250-400 μL) for the measurement of cytokines. The rats that received SEB had an inflammatory response when compared to control rats as shown by an increase in white cell count. TNF-α and IL-6 were detected in the EBC. Concentration of TNF-α correlated with that in the lavage (r = .497, P = .021), whereas IL-6 did not. EBC can be collected in rats in sufficient quantities to study acute lung injury. TNF-α and IL-6 can be measured in the EBC. Correlation between TNF-α in the EBC and lavage was demonstrated in this rat model of lung injury.

Incidence of ionized hypocalcemia in septic dogs and its association with morbidity and mortality: 58 cases (2006-2007)

OBJECTIVE

To determine the incidence rate and prognostic significance of ionized hypocalcemia (iHCa) among septic dogs.

DESIGN

Retrospective study.

SETTING

Veterinary teaching hospital.

ANIMALS

Fifty-eight septic dogs that were presented to Cornell University Hospital for Animals between January 2006 and December 2007.

PROCEDURE

Cases were diagnosed with sepsis if they exhibited 2 or more criteria of the systemic inflammatory response syndrome with a concurrent documented infectious focus. Cases were excluded if diagnosed with a concurrent illness reportedly associated with calcium derangements. Lowest, mean, and highest blood ionized calcium concentrations were recorded and statistically analyzed for an association with morbidity, as measured by duration of hospitalization and number of blood product transfusions, and outcome. In addition, the incidence rate of iHCa was recorded.

RESULTS

Of the 58 cases included in this study, iHCa was documented in 4 of 6 (67%) patients that died, 5 of 19 (26%) euthanized patients and 5 of 33 (15%) patients that survived to discharge, with an overall incidence of 24%. Dogs that died during hospitalization had more severe iHCa than patients that were discharged or euthanized as well as significantly lower mean ionized calcium concentrations than patients who were discharged. Severity of iHCa was also associated with a longer duration of hospitalization. The highest ionized calcium concentration was not associated with outcome.

CONCLUSION AND CLINICAL RELEVANCE

This study is the first to document the incidence of iHCa among septic dogs. Because both low mean ionized calcium and the lowest documented ionized calcium concentration are associated with poor outcome, it is likely that both the severity and duration of hypocalcemia are important in these patients. Further prospective studies investigating the prognostic significance, etiology and treatment of iHCa among septic veterinary patients are needed to better understand its role in sepsis.

The influence of infection sites on development and mortality of ARDS

OBJECTIVE

Infection is the most frequent cause of acute respiratory distress syndrome (ARDS). However, little is known about the influence of infection sites on ARDS. This study aimed to assess the associations of infection sites with ARDS development and mortality in critically ill infected patients.

DESIGN

Prospective observational study.

SETTING

Adult intensive care units (ICUs) of an academic medical center.

PATIENTS

Study population included 1,973 consecutive patients admitted to ICUs with bacteremia, pneumonia or sepsis. During follow-up, 549 patients developed ARDS and 212 of them died within 60 days.

MAIN RESULTS

The distribution of infection sites in ARDS patients was: lung (77.2%), abdomen (19.3%), skin/soft tissues (6.0%), urinary tract (4.7%), unknown (2.6%), and multiple sites (17.7%). On multivariate analysis, lung was the only infection site associated with increased ARDS risk [adjusted odds ratio (OR) 3.49]. Urinary tract (adjusted OR 0.43), skin/soft tissue (adjusted OR 0.64), and unknown-site infections (adjusted OR 0.38) were associated with decreased risk. No association was found between individual infection site and ARDS mortality. However, unknown-site [adjusted hazard ratio (HR) 3.08] and multiple-site infections (adjusted HR 1.63) were associated with increased ARDS mortality. When grouping patients into pulmonary, nonpulmonary, and combined infections, nonpulmonary infection was associated with decreased ARDS risk (adjusted OR 0.28) and combined infections was associated with increased ARDS mortality (adjusted HR 1.69), compared with pulmonary infection.

CONCLUSIONS

In critically ill infected patients, pulmonary infection is associated with higher risk of ARDS development than are infections at other sites. Pulmonary versus nonpulmonary infection significantly affects ARDS development but not mortality.

INDUCTION OF INDUCIBLE NITRIC OXIDE SYNTHASE BY LIPOPOLYSACCHARIDE/INTERFERON GAMMA AND SEPSIS DOWN-REGULATES 5-LIPOXYGENASE METABOLISM IN MURINE ALVEOLAR MACROPHAGES

Pretreatment with lipopolysaccharide (LPS) suppresses rat alveolar macrophage leukotriene synthesis in a nitric oxide (NO)-dependent mechanism. The authors examined the effect of NO on alveolar macrophage leukotriene synthesis following in vitro and in vivo models of sepsis. Treatment of alveolar macrophages from inducible NO synthase (iNOS) wild-type but not knock-out mice with LPS inhibited leukotriene synthesis. iNOS was induced early in alveolar macrophages from cecal ligation and puncture rats and mice compared to sham animals with associated reduced leukotriene synthesis. iNOS knock-out mice were protected from the decrease in alveolar macrophage 5-lipoxygenase metabolism. iNOS regulates alveolar macrophage 5-lipoxygenase metabolism following endotoxin exposure.

Effects of IGM-enriched solution on polymorphonuclear neutrophil function, bacterial clearance, and lung histology in endotoxemia

Immunological interventions in endotoxemia and sepsis have been tested in experimental and clinical studies. Our group evaluated the effects of an immunoglobulin (Ig)M-enriched solution in an established model of Gram-negative bacteraemia. Ten New Zealand White rabbits (2-3 kg) were randomized to a treatment or control group. In both groups, LPS was infused at a rate of 40 mg kg(-1) h(-1). Immunoglobulin M-enriched solution (Pentaglobin; 2 mL kg(-1) h(-1)) was applied in the intervention group 15 min after beginning LPS infusion. 1 x 10(8) colony forming units of Escherichia coli were injected 30 min after LPS infusion was commenced. Baseline hemodynamic and respiratory parameters, blood E. coli concentration (30 min before and 1, 15, 30, 60, 90, 120, and 180 min after E. coli injection), polymorphonuclear neutrophil oxidative burst activity, and phagocytosis dead space (both 30 min before and 1, 15, 60, 120, and 180 min postinjection) were measured. Ex vivo phagocytosis activity was measured in a separate experiment and evaluated by electron microscopy. Diffuse alveolar damage (DAD) was measured. Organ colonization (kidney, lung, liver, spleen) was assessed in aseptic organ samples. Hemodynamic parameters did not differ between the two groups. Bacterial blood clearance was not influenced by application of IgM-enriched solution. Liver and spleen colonization was significantly reduced in the IgM group. Immunoglobulin M-enriched solution reduced in vitro residual phagocytosis capacity at 30, 90, and 180 min and improved respiratory burst at 180 min. Correspondingly, ex vivo phagocytosis activity as documented by electron microscopy was increased in the IgM group. The sum of all weighted DAD scores (except overdistension) was significantly better in the IgM group (23+/-5 vs. 30+/-8). Immunoglobulin M-enriched solution significantly improved six of seven DAD score parameters and reduced liver and spleen E. coli count. Residual phagocytosis capacity was significantly decreased in the IgM group, whereas burst activity was increased, pointing to an increased in vivo phagocytosis efficiency. Short-term IgM-enriched solution intervention had an especially beneficial effect on LPS-induced pulmonary histological changes.

Role of TNFalpha in pulmonary pathophysiology

Tumor necrosis factor alpha (TNFα) is the most widely studied pleiotropic cytokine of the TNF superfamily. In pathophysiological conditions, generation of TNFα at high levels leads to the development of inflammatory responses that are hallmarks of many diseases. Of the various pulmonary diseases, TNFα is implicated in asthma, chronic bronchitis (CB), chronic obstructive pulmonary disease (COPD), acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In addition to its underlying role in the inflammatory events, there is increasing evidence for involvement of TNFα in the cytotoxicity. Thus, pharmacological agents that can either suppress the production of TNFα or block its biological actions may have potential therapeutic value against a wide variety of diseases. Despite some immunological side effects, anti-TNFα therapeutic strategies represent an important breakthrough in the treatment of inflammatory diseases and may have a role in pulmonary diseases characterized by inflammation and cell death.

Chest Pain: A Clinical Assessment

Chest pain is one of the most common presentations in emergency medicine. The initial evaluation should always consider life-threatening causes such as aortic dissection, pulmonary embolism, pneumothorax, pneumomediastinum, pericarditis, and esophageal perforation. Radiographic imaging is performed in tandem with the initial clinical assessment and stabilization of the patient. Radiologic findings are key to diagnosis and management of this entity.

Sepsis: Still Going Strong

Sepsis definitions help to understand and to better define a group of syndromes secondary to an infectious insult. The hierarchical continuum of inflammatory response leads, in absence of counterregulatory forces, to organ damage and death. We have learned first the response to treatment and afterwards the pathophysiology behind it. This lesson has, of course, not always been followed by a reduction of mortality. The definition, natural history, risk factors, diagnoses, and treatment based on emerging evidence will help to improve patient outcomes and mortality. Standardized care seems to improve survival, and validation and further evaluation of this care is necessary to maximize resources and outcomes.

Leukotrienes: underappreciated mediators of innate immune responses

Leukotrienes are bronchoconstrictor and vasoactive lipid mediators that are targets in the treatment of asthma. Although they are increasingly recognized to exert broad proinflammatory effects, their role in innate immune responses is less well appreciated. These molecules are indeed synthesized by resident and recruited leukocytes during infection. Acting via cell surface G protein-coupled receptors and subsequent intracellular signaling events, they enhance leukocyte accumulation, phagocyte capacity for microbial ingestion and killing, and generation of other proinflammatory mediators. Interestingly, a variety of acquired states of immunodeficiency, such as HIV infection and malnutrition, are characterized by a relative deficiency of leukotriene synthesis. The data reviewed herein point to leukotrienes as underappreciated yet highly relevant mediators of innate immunity.

Recovery of bacteria by continuous renal replacement therapy in septic shock and by ultrafiltration from an in vitro model of bacteremia*

BACKGROUND

Severe sepsis is frequently associated with inflammation, multiple-organ dysfunction syndrome, and the accumulation of excess fluid that can be removed by continuous renal replacement therapy. Appropriate therapy for sepsis requires knowledge of the antibiotic susceptibility of the causative organism. However, bacterial isolation and identification are often unsuccessful. The objective of this study was to determine whether bacteria could be recovered from continuous renal replacement therapy ultrafiltrates of clinically septic patients who were either blood culture positive or repeatedly culture negative.

DESIGN

Clinical study.

SETTING

Adult medical intensive care unit.

SUBJECTS

Six clinically septic, blood culture-positive or repeatedly culture-negative patients and four clinically nonseptic patients.

INTERVENTIONS

We performed continuous renal replacement therapy on patients. In addition, we devised an in vitro system mimicking human bacteremia to determine whether bacteria traverse the hemofilter. In these experiments, a reservoir containing reconstituted blood was inoculated with Enterococcus faecalis and hemofiltered. The ultrafiltrates were centrifuged or secondarily filtered for bacterial recovery.

MEASUREMENTS AND MAIN RESULTS

Bacterial pathogens were recovered in culture from ultrafiltrates of all the clinically septic patients. Ultrafiltrates of the nonseptic patients were sterile. E. faecalis, the bacterium inoculated into the reconstituted blood, was the only organism recovered from the in vitro-derived ultrafiltrates.

CONCLUSIONS

Pathogenic bacteria were shown to traverse the hemofilter. Culture of ultrafiltrates of clinically septic, blood culture-negative patients may be useful in recovery of the etiological organism and confirmation of the clinical diagnosis and management of sepsis.

New approaches to the treatment of sepsis

The clinical spectrum of sepsis, severe sepsis, and septic shock is responsible for a growing number of deaths and excessive health care expenditures. Until recently, despite multiple clinical trials, no intervention provided a beneficial outcome in septic patients. Within the last 2 years, studies that involved drotrecogin alfa (activated), corticosteroid therapy, and early goal-directed therapy showed efficacy in those with severe sepsis and septic shock. These results have provided optimism for reducing sepsis-related mortality.

Resource utilization among patients with sepsis syndrome

OBJECTIVE

To assess the resource utilization associated with sepsis syndrome in academic medical centers.

DESIGN

Prospective cohort study.

SETTING

Eight academic, tertiary-care centers.

PATIENTS

Stratified random sample of 1,028 adult admissions with sepsis syndrome and all 248,761 other adult admissions between January 1993 and April 1994. The main outcome measures were length of stay (LOS) in total and after onset of sepsis syndrome (post-onset LOS) and total hospital charges.

RESULTS

The mean LOS for patients with sepsis was 27.7 +/- 0.9 days (median, 20 days), with sepsis onset occurring after a mean of 8.1 +/- 0.4 days (median, 3 days). For all patients without sepsis, the LOS was 7.2 +/- 0.03 days (median, 4 days). In multiple linear regression models, the mean for patients with sepsis syndrome was 18.2 days, which was 11.0 days longer than the mean for all other patients (P < .0001), whereas the mean difference in total charges was $43,000 (both P < .0001). These differences were greater for patients with nosocomial as compared with community-acquired sepsis, although the groups were similar after adjusting for pre-onset LOS. Eight independent correlates of increased post-onset LOS and 12 correlates of total charges were identified.

CONCLUSIONS

These data quantify the resource utilization associated with sepsis syndrome, and demonstrate that resource utilization is high in this group. Additional investigation is required to determine how much of the excess post-onset LOS and charges are attributable to sepsis syndrome rather than the underlying medical conditions.

Imaging of pneumonia: trends and algorithms

Pneumonia is one of the major infectious diseases responsible for significant morbidity and mortality throughout the world. Imaging plays a crucial role in the detection and management of patients with pneumonia. This review article discusses the different imaging methods used in the diagnosis and management of suspected pulmonary infections. The imaging examination should always begin with conventional radiography. When the results of routine radiography are inconclusive, computed tomography is mandatory. A combination of pattern recognition with knowledge of the clinical setting is the best approach to the pulmonary infectious processes. A specific pattern of involvement can suggest a likely diagnosis in many instances. In acquired immune deficiency syndrome patients, diffuse ground-glass and interstitial infiltrates are most commonly present in Pneumocystis carinii pneumonia whereas in the nonimmunosuppressed patients, a segmental lobar infiltrate is suggestive of a bacterial pneumonia. Round pneumonia is most often encountered in children than adults and is most often caused by Streptococcus pneumoniae. Different combinations of parenchymal and pleural abnormalities may be suggestive for additional diagnoses. When an infectious pulmonary process is suspected, knowledge of the varied radiographic manifestations will narrow the differential diagnosis, helping to direct additional diagnostic measures, and serving as an ideal tool for follow-up examinations.

Intrapulmonary TNF gene therapy reverses sepsis-induced suppression of lung antibacterial host defense

Sepsis syndrome is frequently complicated by the development of nosocomial infections, particularly Gram-negative pneumonia. Although TNF-alpha (TNF) has been shown to mediate many of the pathophysiologic events in sepsis, this cytokine is a critical component of innate immune response within the lung. Therefore, we hypothesized that the transient transgenic expression of TNF within the lung during the postseptic period could augment host immunity against nosocomial pathogens. To test this, mice underwent 26-gauge cecal ligation and puncture (CLP) as a model of abdominal sepsis, followed 24 h later by intratracheal (i.t.) administration of Pseudomonas aeruginosa. In animals undergoing sham surgery followed by bacterial challenge, Pseudomonas were nearly completely cleared from the lungs by 24 h. In contrast, mice undergoing CLP were unable to clear P. aeruginosa and rapidly developed bacteremia. Alveolar macrophages (AM) recovered from mice 24 h after CLP produced significantly less TNF ex vivo, as compared with AM from sham animals. Furthermore, the adenoviral mediated transgenic expression of TNF within the lung increased survival in CLP animals challenged with Pseudomonas from 25% in animals receiving control vector to 91% in animals administered recombinant murine TNF adenoviral vector. Improved survival in recombinant murine TNF adenoviral vector-treated mice was associated with enhanced lung bacterial clearance and proinflammatory cytokine expression, as well as enhanced AM phagocytic activity and cytokine expression when cultured ex vivo. These observations suggest that intrapulmonary immunostimulation with TNF can reverse sepsis-induced impairment in antibacterial host defense.

Incidence and susceptibility of pathogenic bacteria vary between intensive care units within a single hospital: implications for empiric antibiotic strategies

BACKGROUND

The purpose of this study was to determine whether the incidence of recovery and patterns of antibiotic susceptibility of pathogenic bacteria vary between intensive care units (ICUs) in a single teaching hospital.

METHODS

Culture and susceptibility results were collected prospectively for a 3-month period (April through June 1999) in each of the surgical, trauma, and medical ICUs. The number of unique isolates and susceptibility patterns were determined. Susceptibility of isolates among ICUs was compared with chi2.

RESULTS

Statistically significant differences between ICUs in susceptibility to various antibiotics were found for Staphylococcus aureus, Enterococcus sp, Acinetobacter sp, Enterobacter sp, Klebsiella sp, and Pseudomonas sp. Notably, vancomycin-resistant Enterococcus was not seen in the medical ICU, whereas it was seen in both the surgical and trauma ICUs. Klebsiella spp resistant to ceftazidime were seen only in the trauma ICU. The aminoglycosides and quinolones had attenuated activity against Pseudomonas sp in the surgical ICU, whereas they remained highly effective in the trauma ICU. Cefazolin had no activity against the Enterobacter sp in either of the surgical ICUs, but was highly effective in the medical ICU.

CONCLUSION

Although the microbiologic results of this study should not be extrapolated to other institutions, the principle is of value. There is variability between ICUs in a single large teaching hospital in susceptibility of bacterial pathogens to various antibiotics. This may have implications in the design of empiric antibiotic strategies and the planning of the hospital formulary. Hospital wide or composite ICU antibiograms are inadequate for planning empiric therapy in the ICU.

Prolonged exposure to lipopolysaccharide inhibits macrophage 5-lipoxygenase metabolism via induction of nitric oxide synthesis

LPS from bacteria can result in the development of sepsis syndrome and acute lung injury. Although acute exposure to endotoxin primes leukocytes for enhanced synthesis of leukotrienes (LT), little is known about the effect of chronic exposure. Therefore, we determined the effect of prolonged LPS treatment on 5-lipoxygenase (5-LO) metabolism of arachidonic acid in alveolar macrophages (AM) and in peripheral blood monocytes. Pretreatment of AM with LPS caused time- and dose-dependent suppression of LT synthetic capacity. LPS pretreatment failed to inhibit arachidonic acid (AA) release. The fact that LPS inhibited LT synthesis from endogenous AA more than from exogenous AA suggested an effect on 5-LO-activating protein (FLAP). In addition, an inhibitory effect of LPS treatment on AM 5-LO activity was suggested by cell-free 5-LO enzyme assay. No effect on the expression of either 5-LO or FLAP proteins was observed. New protein synthesis was necessary for LPS-induced reduction of 5-LO metabolism in AM, and immunoblotting demonstrated marked induction of NO synthase (NOS). Inhibition by LPS was reproduced by an NO donor and was abrogated by inhibitors of constitutive and inducible NOS. Compared with AM, peripheral blood monocytes exhibited no suppression by LPS of 5-LO metabolism and no induction of inducible NOS. We conclude that prolonged exposure to LPS impairs AM 5-LO metabolism by NO-mediated suppression of both 5-LO and FLAP function. Because LT contribute to antimicrobial defense, this down-regulation of 5-LO metabolism may contribute to the increased susceptibility to pneumonia in patients following sepsis.

Acute lung injury and acute respiratory distress syndrome in sepsis and septic shock

Sepsis remains the leading cause of ARDS, and ARDS is still an often fatal condition. With our expanding knowledge of the pathobiologic mechanisms and the relationship between these two entities, early recognition, treatment, and prevention of sepsis may prevent or hasten recovery from ARDS. Understanding the biologic markers involved in the complex inflammatory response of sepsis and acute lung injury offers the possibility of future investigations to target treatment based on these mediators.

Calcitonin precursors are reliable markers of sepsis in a medical intensive care unit

OBJECTIVE

The diagnosis of infection in critically ill patients is challenging because traditional markers of infection are often misleading. For example, serum concentrations of calcitonin precursors are increased in patients with infections. However, their predictive accuracy for the diagnosis of sepsis in unselected patients in a medical intensive care unit (ICU) is unknown. Therefore, we compared the usefulness of serum concentrations of calcitonin precursors, C-reactive protein, interleukin-6, and lactate for the diagnosis of sepsis in consecutive patients suffering from a broad range of diseases with an anticipated stay of > or =24 hrs in a medical ICU.

DESIGN

Prospective cohort study.

SETTING

Medical intensive care unit in a university medical center.

PATIENTS

101 consecutive critically ill patients.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Blood samples were collected at various time points during the course of the disease. Systemic inflammatory response syndrome, sepsis, severe sepsis, and septic shock were diagnosed according to standardized criteria, and patients were reclassified daily without prior knowledge of the serum concentrations of calcitonin precursors or interleukin-6. At admission, 99% of the patients had systemic inflammatory response syndrome, 53% had sepsis, and 5% developed sepsis during their stay in the ICU. Calcitonin precursors, C-reactive protein, interleukin-6, and lactate levels increased with the severity of infection (p < .01, one-way analysis of variance). In a receiver operating characteristic curve analysis, calcitonin precursors were found to be the most reliable laboratory variable for the diagnosis of sepsis as compared with C-reactive protein, interleukin-6, and lactate (p < .01, for each comparison). Calcitonin precursor concentrations of >1 ng/mL had sensitivity of 89% and specificity of 94% for the diagnosis of sepsis. High serum concentrations of calcitonin precursors were associated with poor prognosis (p = .01).

CONCLUSIONS

In a medical ICU, serum calcitonin precursor concentrations are more sensitive and are specific markers of sepsis as compared with serum C-reactive protein, interleukin-6, and lactate levels.

Tumor necrosis factor-alpha inhibits expression of CTP:phosphocholine cytidylyltransferase

We investigated the effects of tumor necrosis factor alpha (TNFalpha), a key cytokine involved in inflammatory lung disease, on phosphatidylcholine (PtdCho) biosynthesis in a murine alveolar type II epithelial cell line (MLE-12). TNFalpha significantly inhibited [(3)H]choline incorporation into PtdCho after 24 h of exposure. TNFalpha reduced the activity of CTP:phosphocholine cytidylyltransferase (CCT), the rate-regulatory enzyme within the CDP-choline pathway, by 40% compared with control, but it did not alter activities of choline kinase or cholinephosphotransferase. Immunoblotting revealed that TNFalpha inhibition of CCT activity was associated with a uniform decrease in the mass of CCTalpha in total cell lysates, cytosolic, microsomal, and nuclear subfractions of MLE cells. Northern blotting revealed no effects of the cytokine on steady-state levels of CCTalpha mRNA, and CCTbeta mRNA was not detected. Incorporation of [(35)S]methionine into immunoprecipitable CCTalpha protein in pulse and pulse-chase studies revealed that TNFalpha did not alter de novo synthesis of enzyme, but it substantially accelerated turnover of CCTalpha. Addition of N-acetyl-Leu-Leu-Nle-CHO (ALLN), the calpain I inhibitor, or lactacystin, the 20 S proteasome inhibitor, blocked the inhibition of PtdCho biosynthesis mediated by TNFalpha. TNFalpha-induced degradation of CCTalpha protein was partially blocked by ALLN or lactacystin. CCT was ubiquitinated, and ubiquitination increased after TNFalpha exposure. m-Calpain degraded both purified CCT and CCT in cellular extracts. Thus, TNFalpha inhibits PtdCho synthesis by modulating CCT protein stability via the ubiquitin-proteasome and calpain-mediated proteolytic pathways.

Continuous flow peritoneal dialysis as a method to treat severe anasarca in children with acute respiratory distress syndrome

OBJECTIVE

To describe a method of rapid fluid removal in children with anasarca and the acute respiratory distress syndrome (ARDS) secondary to sepsis or the systemic inflammatory response syndrome.

DESIGN

Consecutive case series.

SETTING

Pediatric Intensive Care Unit of a children's hospital.

PATIENTS

Six patients with ARDS secondary to sepsis or systemic inflammatory response syndrome, who had persistent anasarca complicating their respiratory course despite intravenous diuretic therapy.

INTERVENTIONS

Continuous flow peritoneal dialysis (CFPD) was instituted after percutaneously inserting two Tenckhoff dialysis catheters into the peritoneal cavity of each patient and tunneling them through the subcutaneous tissue to exit from opposite lower abdominal quadrants. A dialysis solution with 2.5% dextrose was administered continuously via one of the catheters at a rate ranging from 10-30 mL/kg/hr, and concomitantly drained via the other catheter. The concentration of the dialysis solution and rate of inflow were adjusted as needed to achieve the desired peritoneal outflow rate. CFPD was discontinued when adequate weight loss had occurred and the patient's daily urine output exceeded their daily fluid intake. The patient's overall fluid balance and change in weight were recorded daily. The PaO2/FiO2 ratio, alveolar-arterial oxygen gradient, and oxygenation index were also calculated daily.

MEASUREMENTS AND MAIN RESULTS

Six patients with ARDS, mean age 18.7+/-37.0 months were mechanically ventilated for 8.0+/-4.0 days before CFPD, during which time average body weight increased to 63%+/-22% above admission body weight, despite the use of intravenous diuretic therapy. They underwent CFPD for 126.7+/-60.0 hrs, during which time their body weight decreased to 30%+/-12% above admission weight (p<.05). During dialysis, the dialysis outflow rate exceeded the inflow rate by 4.2+/-0.9 mL/kg/hr. When compared with values calculated immediately before starting CFPD, post-CFPD PaO2/FiO2 increased from 97.0+/-32.0 to 215.0+/-40.4 mm Hg (12.9+/-4.3 to 28.7+/-5.4 kPa) (p<.05), post-CFPD alveolar-arterial oxygen gradient decreased from 390.7+/-85.8 to 206.7+/-72.8 mm Hg (52.1+/-11.4 to 27.6+/-9.7 kPa) (p<.05), and post-CFPD the oxygenation index decreased from 29.6+/-9.8 to 11.8+/-5.6 (p<.05). There were no complications associated with dialysis catheter insertion or CFPD therapy. Four patients survived. Two patients had an irreversible course of infections and septic shock and died.

CONCLUSION

Severe anasarca in the course of ARDS can be effectively treated in pediatric patients with continuous flow peritoneal dialysis, resulting in a significant improvement in respiratory status.

Estudo de crianças com síndrome do desconforto respiratório agudo: correlação anatomoclínica radiológica

Estudo retrospectivo com revisão dos casos clínicos de Síndrome do Desconforto Respiratório Agudo, realizado no período de out/88 a dez/90 na Unidade de Pacientes Graves do Instituto Fernandes Figueira. Os autores estudaram as características clínicas, radiológicas e histopatológicas de acordo com o estágio evolutivo da doença. Dentre 459 casos estudados, foram selecionados 49 (11%). Onze casos tiveram exame anatomopatologico [biopsia (4), necropsia (8)] e foram classificados de acordo com o estágio evolutivo em: fase exsudativa inicial, fase proliferativa celular e fase proliferativa fibrótica. Houve correlação clínica radiológica e anatomopatológica nos casos confirmados com exame histológico. Os autores consideram importante estudos futuros em que a interação entre a pesquisa clínica e experimental permita o melhor conhecimento desta Síndrome na população pediátrica.

New Frontiers in Cytokine Involvement during Experimental Sepsis

Despite significant advances in the antibiotic arsenal and in intensive care unit technology, including mechanical ventilation, sepsis-related morbidity and mortality remain unacceptably high. Ultimately, 25 to 50% of all septic episodes end in death. However, various subsets of septic patients, including those who experience septic peritonitis, and various secondary sequelae like the acute respiratory distress syndrome or nosocomial infections, demonstrate much higher mortality rates ranging from 60 to 95%. Although a number of strategies have been utilized to curb the progression of systemic inflammatory response syndrome with immune or inflammatory modulating therapies, none of these interventions has resulted in significant improvement in survival, and some have proven deleterious. The inability to utilize immune-modulating strategies effectively to treat septic patients likely reflects the inherent conflict that is illustrated by the two diagnostic criteria for the syndrome. The very immune/inflammatory response that has evolved to eliminate infection results in severe and life-threatening damage to host tissues. This review outlines the inflammatory pathways utilized by the host during a septic response. The basis of early immune-modulating therapies and possible reasons these approaches have failed in the treatment of sepsis are discussed. A picture of the ideal therapeutic approach for acute inflammatory diseases like sepsis is also created, and the reason therapies targeting chemokine pathways may more closely approximate the ideal therapy is proposed.

The epidemiology of bacterial sepsis

As a result of better understanding of pathogenesis, new definitions of sepsis have been proposed, and the complexity of this syndrome is clearer. Population-based studies of bloodstream infections--what now is called sepsis--have helped us to understand the natural history of this very frequent problem. The mortality and morbidity of each of the systemic inflammatory response syndrome stages have been described; our ability to better understand and predict these stages will help us to make better therapeutic decisions.

Acute lung injury, acute respiratory distress syndrome and inhalation injury: an overview

Acute Lung Injury (ALI) and the Acute Respiratory Distress Syndrome (ARDS) are severe respiratory diseases that have a very poor prognosis and have numerous causes. Despite a great deal of research and investigation since the initial description of ARDS 30 years ago many questions about the pathogenesis, treatment and outcome of the disease remain unanswered. Although there is evidence to suggest that outcome of ALI and ARDS is improving, the reasons why are unknown and there is not yet a well developed treatment for these diseases. Inhalation injury resulting from exposure to pyrolysis and combustion atmospheres is among the causes of ALI/ARDS. Little is known of the mechanisms of fire related inhalation injury that results in the development of ALI/ARDS. There is a paucity of information about fire atmosphere exposure response relationships for smoke-induced inhalation injury. Although there is considerable information about the pulmonary toxicity of many of the more common constituents of fire atmospheres, little is known about the pulmonary toxicity of mixtures of these constituents. Fire related pulmonary health risks are of particular concern to the Navy due to the limited opportunity to escape the inhalation hazards posed by shipboard fires. Consequently the Naval Medical Research Institute Detachment (Toxicology) has undertaken a research program to develop research models of combustion atmosphere induced ALI/ARDS which can be exploited to systematically address some of the questions surrounding fire related ALI/ARDS. ALI/ARDS has been the topic of a vast amount of research, numerous symposia, working groups and their published proceedings, book chapters, and books. Less information is available regarding experimental models of smoke induced lung damage, however the literature on the subject is extensive. Consequently this article is intended to provide the reader with a primer or cursory "overview" of ALI and ARDS from a toxicological perspective and should not be considered comprehensive.

IL-10 Is a Major Mediator of Sepsis-Induced Impairment in Lung Antibacterial Host Defense

To explore the mechanism of immunosuppression associated with sepsis, we developed a murine model of sepsis-induced Pseudomonas aeruginosa pneumonia. CD-1 mice underwent either cecal ligation and 26-gauge needle puncture (CLP) or sham surgery, followed by the intratracheal (i.t.) administration of P. aeruginosa or saline. Survival in mice undergoing CLP followed 24 h later by the i.t. administration of saline or P. aeruginosa was 58% and 10%, respectively, whereas 95% of animals undergoing sham surgery followed by P. aeruginosa administration survived. Increased mortality in the CLP/P. aeruginosa group was attributable to markedly impaired lung bacterial clearance and the early development of P. aeruginosa bacteremia. The i.t. administration of bacteria to CLP-, but not sham-, operated mice resulted in an impressive intrapulmonary accumulation of neutrophils. Furthermore, P. aeruginosa challenge in septic mice resulted in a relative shift toward enhanced lung IL-10 production concomitant with a trend toward decreased IL-12. The i.p., but not i.t., administration of IL-10 Abs given just before P. aeruginosa challenge in septic mice significantly improved both survival and clearance of bacteria from the lungs of septic animals administered P. aeruginosa. Finally, alveolar macrophages isolated from animals undergoing CLP displayed a marked impairment in the ability to ingest and kill P. aeruginosa ex vivo, and this defect was partially reversed by the in vivo neutralization of IL-10. Collectively, these observations indicate that the septic response substantially impairs lung innate immunity to P. aeruginosa, and this effect is mediated primarily by endogenously produced IL-10.

Histopathology of ventilator-associated pneumonia (VAP) and its clinical implications

Ventilator-associated pneumonia (VAP) is a diffuse polymicrobial and dynamic process, with heterogeneous distribution of lesions, showing different degrees of histological evolution predominating in the dependent lung zones, in which microbiology and histology can be dissociated. This might explain why blind endobronchial techniques to collect respiratory secretions have similar accuracy compared to visually guided samples, explaining the difficulties in validating any methods for its diagnosis. In the clinical setting the association of acute lung injury (ALI) and pneumonia is controversial. However, it is rare to detect diffuse alveolar damage (DAD) in absence of histological signs of pneumonia, probably evidencing that ALI favors the development of pneumonia. Histopathologically, it is difficult to distinguish initial and resolution phases of DAD from pneumonia and vice versa. On the other hand, there is a clear relationship between antimicrobial treatment and the decreased lung bacterial burden which strengthens the importance of distal airway sampling before starting antibiotic therapy.

Changing bacterial ecology during a five-year period of selective intestinal decontamination

The development of bacterial resistance during selective decontamination of the digestive tract (SDD) is controversial. We studied effects on bacterial resistance one year before and during a randomized, placebo-controlled trial of SDD in a surgical intensive care unit. We randomized patients within two different topical regimens (PTA, PCA) or placebo, administered four-times daily to both the oropharynx and gastrointestinal tract. All patients received intravenous ciprofloxacin (200 mg b.d.) for four days. Both SDD regimens successfully reduced aerobic Gram-negative intestinal colonization. There was no increase in resistance of Enterobacteriaceae or Pseudomonas aeruginosa. Acinetobacter calcoaceticus developed multi-resistance over one year, but differences between groups were not significant. We detected a shift towards Gram-positive organisms. Oxacillin-resistant Staphylococcus aureus increased in concert with ciprofloxacin resistance, from 17 to 80.7%, and frequencies of resistance were significantly higher in SDD patients (P < 0.001). Resistance of coagulase-negative staphylococci (CNS) to oxacillin increased initially (25 to 66.9%), but values returned to baseline in controls. Ciprofloxacin resistance in CNS remained higher (P < 0.001) in SDD-treated patients (52.5 vs. 23.3%). The incidence of late respiratory tract infections was unaltered by the prophylactic regimen (SDD 35.2%; Placebo 41.2%; n.s.). We cannot recommend SDD as a prophylactic tool in critically ill patients.

Reduced lipid peroxidation and ischemia-reperfusion injury after lung transplantation using low-potassium dextran solution for lung preservation

Ischemia-reperfusion injury is one of the significant problems in clinical lung transplantation. We investigated the effect of lung preservation with Euro-Collins solution (EC group) or low-potassium dextran solution (LPD group) on lipid peroxidation and ischemia-reperfusion injury in a pig model of lung allotransplantation. The donor lungs were preserved at 4 degrees C for 18 h. Left-sided single lung transplantation was performed, followed by 6 h of reperfusion. Lipid peroxidation was measured as thiobarbituric acid-reactive materials (TBARM) in bronchoalveolar lavage (BAL) fluid and effluent solutions from pulmonary artery (Effluent). After 18 h of ischemia, the LPD group showed lower TBARM in BAL and Effluent than the EC group (p < 0.05). After ischemia plus reperfusion, lung wetto-dry weight ratios and TBARM levels in BAL in the LPD group were lower than those of the EC group (p < 0.05). Lung wet-to-dry weight ratios correlated with TBARM levels in BAL (p < 0.05, r = 0.50). We conclude lipid peroxidation in BAL and Effluent may reflect the degree of ischemia-reperfusion injury, and lung preservation with LPD can reduce lipid peroxidation and lung injury as compared with EC.

Pneumonia in elders

In spite of the availability of potent antibiotics and sophisticated diagnostic techniques, pneumonia continues to be a serious problem among elders. Respiratory infections occur frequently and often are complex. Management is complicated by atypical clinical presentations and altered metabolism of pharmacologic agents. Community-acquired pneumonia and nosocomial pneumonia are caused by different organisms but can have similar clinical presentations. Current therapeutic measures and appropriateness of hospitalization are discussed. Via synthesis and application of this material, nurses can maximize positive outcomes by identifying symptoms, individualizing care, and implementing effective preventive education in the acute care setting, as well as in the community.

Selective intestinal decontamination in multiple trauma patients: prospective, controlled trial

BACKGROUND

Reduction of potential pathogens by selective intestinal decontamination has been proposed to improve intensive care. Despite large scientific interest in this method, little is known about its benefit in homogeneous trauma populations.

METHODS

In a prospective, controlled study, we enrolled non-infected trauma patients (age over 18 years, mechanical ventilation > or = 48 hours, intensive care for more than 3 days) who primarily were admitted to our university medical center. We randomized patients to be treated with two different topical regimens (polymyxin, tobramycin, and amphotericin (PTA) or polymyxin, ciprofloxin, amphotericin (PCA)) or the carrier only (placebo), administered four times daily both to the oropharynx and to the gastrointestinal tract. All patients received intravenous ciprofloxacin (200 mg, bd) for 4 days.

FINDINGS

Of 357 enrolled patients, 310 (age 38.0 +/- 16.5 years, Injury Severity Score 35.2 +/- 12.7) met all inclusion criteria. Selective decontamination successfully reduced intestinal bacterial colonization. However, we did not identify significant differences between groups regarding pneumonia (PTA 47.5%, PCA 39.0%, placebo 45.3%), sepsis (PTA 47.5%, PCA 37.8%, placebo 42.6%), multiple organ failure (PTA 56.3%; PCA 52.4%, placebo 58.1%), and death (PTA 11.3%, PCA 12.2%, placebo 10.8%). Total costs per patient were highest with the PTA regimen.

CONCLUSIONS

We found no benefit of selective decontamination in trauma patients. Apparently, bacterial overgrowth in the intestinal tract is not the sole link between trauma, sepsis, and organ failure.

Comparison of nonbronchoscopic techniques with bronchoscopic brushing in the diagnosis of ventilator-associated pneumonia

OBJECTIVE

To determine the diagnostic accuracy of quantitative cultures obtained via nonbronchoscopic protected specimen brushing (PSB) and nonbronchoscopic bronchoalveolar lavage (BAL) compared with quantitative cultures obtained by bronchoscopic PSB in surgical patients suspected of ventilator-associated pneumonia.

DESIGN

Prospective, crossover controlled study of 15 ventilated surgical intensive care unit patients in a university teaching hospital.

METHODS

Fifteen consecutive ventilated patients suspected of ventilator-associated pneumonia on the basis of leukocytosis, purulent sputum, and appearance of chest roentgenogram were enrolled. All patients underwent nonbronchoscopic PSB and BAL followed by bronchoscopic PSB. The duration of each procedure was noted. Culture results were considered positive only if greater than 10(4) colony forming units (CFU) per milliliter were present.

MAIN RESULTS

Perfect concordance was noted between bronchoscopic PSB and nonbronchoscopic BAL (kappa = 1.0). The concordance between bronchoscopic PSB and nonbronchoscopic PSB was 93% ((kappa = 0.86). The nonbronchoscopic procedures were performed in significantly less time than the bronchoscopic procedure.

CONCLUSION

Nonbronchoscopic PSB and BAL provide similar microbiologic data to bronchoscopic PSB in the diagnosis of ventilator-associated pneumonia while shortening procedure time significantly.

Clostridium difficile infection as a cause of severe sepsis

Although colitis is often seen in critically all patients who have received multiple broad-spectrum antibiotics, there are no reports describing severe sepsis as a result of Clostridium difficile infection. We describe three cases of severe sepsis with local intestinal Clostridium difficile infection as the only identifiable etiology. The mechanism of severe sepsis may be a derangement of the gastrointestinal barrier function. This could result in absorption of microbes or endotoxin or activation of inflammatory cascades in the submucosa of the intestine or liver.

Selective inhibition of the inducible isoform of nitric oxide synthase prevents pulmonary transvascular flux during acute endotoxemia

The inducible isoform of nitric oxide synthase (iNOS) is expressed in various organs, including the lung, during systemic endotoxemia. Overproduction of nitric oxide (NO) by iNOS contributes significantly to the vascular failure and end-organ damage in endotoxemia. Using selective pharmacological inhibitors of iNOS, the purpose of this study was to define the role of iNOS in a rat model of endotoxin-induced pulmonary transvascular flux (TVF). Lung TVF was assessed by a method of Evans Blue permeability index (PI). Bacterial lipopolysaccharide (LPS) (15 mg/kg intraperitoneally [IP]) significantly increased pulmonary iNOS activity and serum levels of nitrite/nitrate (NO2/NO3). This was accompanied by a significant elevation of the PI 5 hours after injection. Selective iNOS inhibition with either S-methyl isothiourea (SMT; 5 mg/kg IP) or aminoguanidine (AG; 20 mg/kg IP), administered 2 hours after LPS injection, significantly prevented the increase in PI associated with LPS injection. Similarly, inhibition of the induction of iNOS with dexamethasone (10 mg/kg IP), given 3 hours before LPS, also inhibited the increase in PI. All three treatments significantly prevented the increase in both lung iNOS activity and serum NO2/NO3 associated with endotoxemia. In conclusion, the overproduction of NO generated by iNOS during systemic endotoxemia causes a vascular leak in the lung. Thus, it is speculated that selective inhibition of iNOS may be beneficial in preventing the development of acute respiratory failure in sepsis.

Epidemiology of sepsis and multiple organ dysfunction syndrome in children

STUDY OBJECTIVES

To determine the cumulated incidence and the density of incidence of systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, septic shock, and multiple organ dysfunction syndrome (MODS) in critically ill children; to distinguish patients with primary from those with secondary MODS.

DESIGN

Prospective cohort study.

SETTING

Pediatric ICU of a university hospital.

PATIENTS

One thousand fifty-eight consecutive hospital admissions.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

SIRS occurred in 82% (n=869) of hospital admissions, 23% (n=245) had sepsis, 4% (n=46) had severe sepsis, 2% (n=25) had septic shock; 16% (n=168) had primary MODS and 2% (n=23) had secondary MODS; 6% (n=68) of the study population died. The pediatric risk of mortality (PRISM) scores on the first day of admission to pediatric ICU were as follows: 3.9 +/- 3.6 (no SIRS), 7.0 +/- 7.0 (SIRS), 9.5 +/- 8.3 (sepsis), 8.8 +/- 7.8 (severe sepsis), 21.8 +/- 15.8 (septic shock); differences among groups (p=0.0001), all orthogonal comparisons, were significant (p<0.05), except for patients with severe sepsis. The observed mortality for the whole study population was also different according to the underlying diagnostic category (p=0.0001; p<0.05 for patients with SIRS and those with septic shock, compared with all groups). Among, patients with MODS, the difference in mortality between groups did not reach significance (p=0.057). Children with secondary MODS had a longer duration of organ dysfunction (p<0.0001), a longer stay in pediatric ICU after MODS diagnosis (p<0.0001), and a higher risk of mortality (odds ratio, 6.5 [2.7 to 15.9], p<0.0001) than patients with primary MODS.

CONCLUSIONS

SIRS and sepsis occur frequently in critically ill children. The presence of SIRS, sepsis, or septic shock is associated with a distinct risk of mortality among critically ill children admitted to the pediatric ICU; more data are needed concerning children with MODS. Secondary MODS is much less common than primary MODS, but it is associated with an increased morbidity and mortality; we speculate that distinct pathophysiologic mechanisms are involved in these two conditions.

Early predictors of sepsis in the motor-vehicle crash trauma victim

INTRODUCTION

Sepsis is a major cause of late morbidity and mortality in the victim of trauma. Currently, there is no method that is clinically practical and accurate for predicting the occurrence of sepsis in trauma victims.

METHODS

Data were collected on 3,759 motor-vehicle crash victims from 16 hospitals during a 4 1/2 year period. Retrospective analysis was done to examine the relationship of patient and injury factors known within the first 24 hours of admission on the development of sepsis.

RESULTS

Sepsis developed in 154 patients (4.1%) who had a mortality rate of 17.5%. Significant early predictors of sepsis included: 1) certain pre-existing conditions; 2) blood transfusion required; 3) seven or more injuries; 4) Glasgow Coma Scale score <10 and hypotension [corrected]; 5) major blood vessel injury; 6) head trauma; 7) internal injury of the chest or abdomen; 8) spinal-cord injury; and 9) certain fracture types.

CONCLUSIONS

These predictors might help target high-risk patients and, thus, promote earlier and more effective treatment for those patients.

Intestinal barrier failure and the development of the systemic inflammatory response syndrome

At the present time, terms used to describe the clinical entity of sepsis are used inappropriately and interchangeably. The source and foci of infection are often unidentified, yet it is clear that some form of inflammatory episode is occurring. The following paper seeks to clarify the terminology used to describe 'sepsis' and link this with a non-bacteraemic source of this inflammatory response--the small intestine. The importance of accurately reflecting oxygen extraction and oxygen consumption by cells is addressed and a movement from the current emphasis on haemodynamic measurement to variables which reflect metabolic rate and lactic acidosis is discussed. Issues which are the concern of nurses working in intensive care are examined, in terms of primary prevention and secondary management.