Use of nebulized antimicrobials for the treatment of respiratory infections in invasively mechanically ventilated adults: a position paper from the European Society of Clinical Microbiology and Infectious Diseases

With an established role in cystic fibrosis and bronchiectasis, nebulized antibiotics are increasingly being used to treat respiratory infections in critically ill invasively mechanically ventilated adult patients. Although there is limited evidence describing their efficacy and safety, in an era when there is a need for new strategies to enhance antibiotic effectiveness because of a shortage of new agents and increases in antibiotic resistance, the potential of nebulization of antibiotics to optimize therapy is considered of high interest, particularly in patients infected with multidrug-resistant pathogens. This Position Paper of the European Society of Clinical Microbiology and Infectious Diseases provides recommendations based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology regarding the use of nebulized antibiotics in invasively mechanically ventilated adults, based on a systematic review and meta-analysis of the existing literature (last search July 2016). Overall, the panel recommends avoiding the use of nebulized antibiotics in clinical practice, due to a weak level of evidence of their efficacy and the high potential for underestimated risks of adverse events (particularly, respiratory complications). Higher-quality evidence is urgently needed to inform clinical practice. Priorities of future research are detailed in the second part of the Position Paper as guidance for researchers in this field. In particular, the panel identified an urgent need for randomized clinical trials of nebulized antibiotic therapy as part of a substitution approach to treatment of pneumonia due to multidrug-resistant pathogens.

Key considerations on nebulization of antimicrobial agents to mechanically ventilated patients

Nebulized antibiotics have an established role in patients with cystic fibrosis or bronchiectasis. Their potential benefit to treat respiratory infections in mechanically ventilated patients is receiving increasing interest. In this consensus statement of the European Society of Clinical Microbiology and Infectious Diseases, the body of evidence of the therapeutic utility of aerosolized antibiotics in mechanically ventilated patients was reviewed and resulted in the following recommendations: Vibrating-mesh nebulizers should be preferred to jet or ultrasonic nebulizers. To decrease turbulence and limit circuit and tracheobronchial deposition, we recommend: (a) the use of specifically designed respiratory circuits avoiding sharp angles and characterized by smooth inner surfaces, (b) the use of specific ventilator settings during nebulization including use of a volume controlled mode using constant inspiratory flow, tidal volume 8 mL/kg, respiratory frequency 12 to 15 bpm, inspiratory:expiratory ratio 50%, inspiratory pause 20% and positive end-expiratory pressure 5 to 10 cm H₂O and (c) the administration of a short-acting sedative agent if coordination between the patient and the ventilator is not obtained, to avoid patient's flow triggering and episodes of peak decelerating inspiratory flow. A filter should be inserted on the expiratory limb to protect the ventilator flow device and changed between each nebulization to avoid expiratory flow obstruction. A heat and moisture exchanger and/or conventional heated humidifier should be stopped during the nebulization period to avoid a massive loss of aerosolized particles through trapping and condensation. If these technical requirements are not followed, there is a high risk of treatment failure and adverse events in mechanically ventilated patients receiving nebulized antibiotics for pneumonia.

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Global survey on nebulization of antimicrobial agents in mechanically ventilated patients: a call for international guidelines

Nebulized antimicrobial agents are increasingly administered for treatment of respiratory infections in mechanically ventilated (MV) patients. A structured online questionnaire assessing the indications, dosages and recent patterns of use for nebulized antimicrobial agents in MV patients was developed. The questionnaire was distributed worldwide and completed by 192 intensive care units. The most common indications for using nebulized antimicrobial agent were ventilator-associated tracheobronchitis (VAT; 58/87), ventilator-associated pneumonia (VAP; 56/87) and management of multidrug-resistant, Gram-negative (67/87) bacilli in the respiratory tract. The most common prescribed nebulized agents were colistin methanesulfonate and sulfate (36/87, 41.3% and 24/87, 27.5%), tobramycin (32/87, 36.7%) and amikacin (23/87, 26.4%). Colistin methanesulfonate, amikacin and tobramycin daily doses for VAP were significantly higher than for VAT (p < 0.05). Combination of parenteral and nebulized antibiotics occurred in 50 (86%) of 58 prescriptions for VAP and 36 (64.2%) of 56 of prescriptions for VAT. The use of nebulized antimicrobial agents in MV patients is common. There is marked heterogeneity in clinical practice, with significantly different in use between patients with VAP and VAT. Randomized controlled clinical trials and international guidance on indications, dosing and antibiotic combinations to improve clinical outcomes are urgently required.

European perspective and update on the management of nosocomial pneumonia due to methicillin-resistant Staphylococcus aureus after more than 10 years of experience with linezolid

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of antimicrobial-resistant hospital-acquired infections worldwide and remains a public health priority in Europe. Nosocomial pneumonia (NP) involving MRSA often affects patients in intensive care units with substantial morbidity, mortality and associated costs. A guideline-based approach to empirical treatment with an antibacterial agent active against MRSA can improve the outcome of patients with MRSA NP, including those with ventilator-associated pneumonia. New methods may allow more rapid or sensitive diagnosis of NP or microbiological confirmation in patients with MRSA NP, allowing early de-escalation of treatment once the pathogen is known. In Europe, available antibacterial agents for the treatment of MRSA NP include the glycopeptides (vancomycin and teicoplanin) and linezolid (available as an intravenous or oral treatment). Vancomycin has remained a standard of care in many European hospitals; however, there is evidence that it may be a suboptimal therapeutic option in critically ill patients with NP because of concerns about its limited intrapulmonary penetration, increased nephrotoxicity with higher doses, as well as the emergence of resistant strains that may result in increased clinical failure. Linezolid has demonstrated high penetration into the epithelial lining fluid of patients with ventilator-associated pneumonia and shown statistically superior clinical efficacy versus vancomycin in the treatment of MRSA NP in a phase IV, randomized, controlled study. This review focuses on the disease burden and clinical management of MRSA NP, and the use of linezolid after more than 10 years of clinical experience.

A European survey of antibiotic management of methicillin-resistant Staphylococcus aureus infection: current clinical opinion and practice

Although the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) varies across Europe, healthcare-associated MRSA infections are common in many countries. Despite several national guidelines, the approach to treatment of MRSA infections varies across the continent, and there are multiple areas of management uncertainty for which there is little clinical evidence to guide practice. A faculty, convened to explore some of these areas, devised a survey that was used to compare the perspectives of infection specialists from across Europe on the management of MRSA infections with those of the faculty specialists. The survey instrument, a web-based questionnaire, was sent to 3840 registered delegates of the 19th European Congress of Clinical Microbiology and Infectious Diseases, held in April 2009. Of the 501 (13%) respondents to the survey, 84% were infection/microbiology specialists and 80% were from Europe. This article reports the survey results from European respondents, and shows a broad range of opinion and practice on a variety of issues pertaining to the management of minor and serious MRSA infections, such as pneumonia, bacteraemia, and skin and soft tissue infections. The issues include changing epidemiology, when and when not to treat, choice of treatment, and duration and route of treatment. The survey identified areas where practice can be improved and where further research is needed, and also identified areas of pan-European consensus of opinion that could be applied to European guidelines for the management of MRSA infection.

Microsatellite analysis of HSV-1 isolates: from oropharynx reactivation toward lung infection in patients undergoing mechanical ventilation

BACKGROUND

According to recent reports, herpes simplex virus type 1 (HSV-1) induces bronchopneumonitis (BPn) in immunocompetent patients undergoing prolonged mechanical ventilation (MV), whose respiratory functions deteriorate with a poor outcome. HSV-1 BPn is associated with HSV symptomatic or symptomless reactivation in the oropharynx.

OBJECTIVES

We sought to systematically and genetically characterize HSV-1 strains isolated from immunocompetent patients receiving prolonged MV and to characterize the genetic relationship of strains sequentially isolated from oropharyngeal samples (OPS) and broncho-alveolar liquids (BAL) to determine the natural course of HSV BPn.

STUDY DESIGN

In this molecular epidemiological study, microsatellite technology was used to determine genetic relationships between 211 HSV-1 strains isolated from OPS and/or BAL from 106 patients receiving MV.

RESULTS

Microsatellite haplotypes of HSV-1 strains sequentially isolated from the same individual were identical, and HSV-1 isolates from the lung were genetically indistinguishable from strains isolated from the oral cavity. Each patient was characterized by their own HSV-1 microsatellite haplotype, and no nosocomial transmission of strains between patients was observed.

CONCLUSION

Our results demonstrate that, in patients who receive MV, the HSV-1 pulmonary infection results from the reactivation of genetically related HSV-1 in the oropharynx, which progressively infects the lower respiratory tract.

Management of methicillin-resistant Staphylococcus aureus infections

This review addresses selected aspects of the management of severe healthcare-associated infections due to methicillin-resistant Staphylococcus aureus (MRSA), including the limitations of current therapy, potential alternative agents, new therapeutic options, clinical approaches to MRSA bacteraemia/endocarditis and ventilator-associated pneumonia, and strategies to improve outcomes in patients with severe MRSA infections.

Posterior reversible encephalopathy syndrome during systemic lupus erythematosus: four new cases and review of the literature

Posterior reversible encephalopathy syndrome (PRES) associates various neurological manifestations (headaches, seizures, altered mental status, cortical blindness, focal neurological deficits, vomiting) and transient changes on neuroimaging consistent with cerebral edema. Posterior reversible encephalopathy syndrome mainly occurs in the setting of hypertension, eclampsia, renal failure and/or use of immunosuppressive drugs. We report four cases of PRES complicating systemic lupus erythematosus (SLE). In all our cases, renal involvement and hypertension were present. Neurological symptoms were typical. Magnetic resonance imaging showed posterior cerebral edema and in one case hemorrhagic complication. With symptomatic treatment and immunosuppressor withdrawal when they were previously used, symptoms fully resolved within 15 days in all cases, but one who had only partial regression related to cerebral hemorrhage. Including our cases, we reviewed a total of 46 patients with SLE and PRES. Their clinical and radiological presentation was not specific. The peculiar role of SLE itself in the occurrence of PRES was not clear, since hypertension (95%), renal involvement (91%), recent onset of immunosuppressive drugs (54%) and/or recent treatment with high intravenous dose of steroids (43%) were often present. The hypertension and other worsening factors should be treated. Finally, the evolution of this clinical and radiological spectacular syndrome is generally rapidly favorable.

Hospital-acquired pneumonia guidelines in Europe: a review of their status and future development

Hospital-acquired pneumonia (HAP) is the most common healthcare-acquired infection contributing to death. Effective management requires accurate diagnosis, administration of a suitable antibiotic regimen early in infection and implementation of prevention strategies. In recent years, there has been a rapid increase in the number of country-specific HAP guidelines in Europe, which vary in their formulation, coverage of different disease aspects and overall recommendations. Development of comprehensive pan-European HAP guidelines would rationalize the conflicting proposals, provide a useful resource and limit guideline proliferation. However, careful consideration needs to be given to the principles of guideline development to ensure that the output is rigorous, broadly applicable and facilitates update as new data becomes available. The use of an evidence-based approach to HAP guideline development is optimal, but is compromised by limitations in the supporting data. The implementation of a formalized evidence grading system is key to introducing consistency into the guideline development process. Pan-European guidelines should provide recommendations on core aspects of HAP common to all treatment settings and locations, and reflect the differing perspectives of the countries involved. Given the different antibiotic susceptibility profiles across Europe, such guidelines should provide general treatment recommendations suitable for local adaptation. The development of such guidelines represents an ideal time to identify priorities for European research, by addressing controversies and identifying previously unconsidered aspects of HAP. Establishing a pan-European consensus on core processes of care should be viewed as an impetus for change to improve clinical practices and should include a suitable implementation strategy.

Diagnosis and treatment of nosocomial pneumonia in ALI/ARDS patients

Ventilator-associated pneumonia (VAP) is a common complication of the acute respiratory distress syndrome (ARDS) or acute lung injury (ALI), often leading to the development of sepsis, multiple organ failure, and death. However, the diagnosis of pulmonary infection in patients with ARDS/ALI is often difficult: the systemic signs of infection, such as fever, tachycardia, leukocytosis are nonspecific findings in such patients; a variety of causes other than pneumonia can explain asymmetric consolidation in patients with ARDS and marked asymmetry of radiographic abnormalities has also been reported in patients with uncomplicated ARDS. In 2003, physicians in charge of these patients have to identify patients with true bacterial lung infection, to select appropriate initial antibiotic therapy, to adjust therapy as soon as possible, and to withhold antibiotics in patients without VAP. To do that, a bacteriological strategy based on the use of quantitative cultures of specimen obtained with fibreoptic bronchoscopy performed before initiation or modification of antibiotic treatment seems better than a strategy based on clinical evaluation alone, lowering antibiotic consumption and improving outcome. When bronchoscopy is not available or contraindicated, a nonbronchoscopic strategy or a clinical strategy with reevaluation 3 days after initiation of treatment may be used. Antimicrobial treatment of VAP is a complex issue. Some general principles can be helpful for the selection of initial treatment: knowledge of most frequently identified responsible pathogens and their susceptibility patterns in the unit; prior duration of hospitalisation; previously prescribed antibiotics; information obtained by direct examination of pulmonary secretions; antibacterial activity and pharmacodynamic characteristics of antibiotics that could be used to treat this infection. Appropriateness of initial antimicrobial therapy is probably a major prognostic factor for patients with ventilator-associated pneumonia. Thus, before new antiboitics are administered, reliable pulmonary specimens must be obtained for direct examination and cultures.

Pseudomonas aeruginosa ventilator-associated pneumonia: comparison of episodes due to piperacillin-resistant versus piperacillin-susceptible organisms

We sought to determine the epidemiological characteristics of patients in an intensive care unit (ICU) who developed ventilator-associated pneumonia (VAP) caused by piperacillin-resistant Pseudomonas aeruginosa (PRPA; n=34) or piperacillin-susceptible P. aeruginosa (PSPA; n=101). According to univariate analysis, the factors associated with the development of PRPA VAP were presence of an underlying fatal medical condition, immunocompromised status, longer previous hospital stay, less-severe illness at the time of ICU admission, duration of mechanical ventilation before onset of VAP, number of classes of antibiotic received, and previous exposure to imipenem or fluoroquinolone. Multivariate logistic regression analysis identified the following significant independent factors: presence of an underlying fatal medical condition (odds ratio [OR], 5.6), previous fluoroquinolone use (OR, 4.6), and initial disease severity (OR, 0.8). We concluded that the clinical characteristics of patients who develop PRPA VAP differ from those of patients who develop PSPA VAP. Restricted fluoroquinolone use is the sole independent risk factor for PRPA VAP that is open to medical intervention.

Is it possible to cure mediastinitis in patients with major postcardiac surgery complications?

BACKGROUND

The prognosis for mediastinitis after cardiac operation has improved during the last two decades, but most series do not include patients who already have a major postoperative complication when the infection developed.

METHODS

Our 9-year prospective study of 371 consecutive patients with mediastinitis compared the characteristics of patients admitted to the intensive care unit primarily for mediastinitis with those who developed mediastinitis after intensive care unit admission for severe postoperative organ failure.

RESULTS

We identified 323 (87%) primary and 48 (13%) secondary mediastinitis patients. The incubation time for mediastinitis was longer for secondary mediastinitis patients, despite similar initial operations. Staphylococcus aureus was responsible for approximately 60% of the episodes in both groups; however, the incidence of methicillin resistance was 2.5 times higher in secondary mediastinitis patients (p < 0.0001). The mediastinitis cure rate was similar for both groups. However, intensive care unit mortality (63% versus 21%), duration of mechanical ventilation (40 versus 9 days), and length of intensive care unit stay (53 versus 28 days) were significantly higher for secondary mediastinitis patients (p < 0.0001).

CONCLUSIONS

The presence of a prior major postoperative complication does not alter the cure rate of mediastinal infections, but does greatly reduce the survival rate.

[Diagnosis and treatment of nosocomial pneumonia: bronchial fibroscopy, protected brushing and/or bronchial lavage is indispensable]

In case of suspected nosocomial lung infection in an intensive care patient, a strictly "clinical" strategy based on the physical exam and qualitative culture of tracheal secretions has three potential drawbacks: i) Numerous patients are given unnecessary antibiotic regimens unwarranted on the sole basis of colonization of the upper airways. In addition to the high cost of such regimens, these antibiotics also have important adverse effects favoring the emergence of multiresistant strains, and in addition, considerably complicating the search for the real cause and the treatment of the fever and the new lung images. ii) This strategy exposes the patient to diagnostic errors by omission if all patients with suspected infection are not treated. iii) Finally, even if the diagnosis of pneumonia is exact, the antibiotic prescribed on the basis of necessarily imprecise information can be most inappropriate or non-optimal in many cases. It is particularly difficult or often impossible to taper off the regimen on day 3 when tracheal cultures become available since the prescription would have to cover all the germs present in the upper airways even though only certain strains are undoubtedly causing the infection in the lung parenchyma. We prefer another strategy based on systematic bronchial fibroscopy before changing the antibiotic regimen in patients presenting signs suggestive of nosocomial pneumonia. The fibroscope allows us to obtain minimally-contaminated or non-contaminated specimens of the distal lung secretions in the suspected zone using the "Wimberley" brush for a protected sample and/or bronchoalveolar lavage. Although data in the literature on the usefulness of protected brushings and bronchoalveolar lavage specimens is rather confusing due to methodological differences, all the published work confirms that these techniques do allow identification of the germs present in the lung at the time of the sampling. Thus, on the basis of the culture results, it would be possible to discontinue any unnecessary antibiotic in patients with negative samples and inversely to use the narrowest possible treatment spectrum for those with positive samples, adapting the regimen to the susceptibility pattern or identified strains. The strongest arguments favoring this invasive strategy come from a multicentric French study on 413 patients with clinically suspected nosocomial pneumonia under artificial ventilation. The results demonstrated lower mortality in the fibroscopy group associated with a major reduction in the consumption of antibiotics.

Oncostatin M production by blood and alveolar neutrophils during acute lung injury

Polymorphonuclear neutrophils (PMN) are involved in the pathogenesis of acute lung injury (ALI), secreting numerous mediators such as proteases, reactive oxygen species, and cytokines. Because we had recently observed the ability of normal human PMN to degranulate and synthesize oncostatin M (OSM), an IL-6-family cytokine, we quantified OSM production ex vivo by highly purified blood and alveolar PMN from 24 ventilated patients with ALI, including some patients with severe pneumonia. Most of the patients had no detectable OSM in plasma, and OSM production by cultured blood PMN was similar to that of healthy controls. However, OSM was present in bronchoalveolar lavage (BAL) fluid supernatant, with significantly higher levels during pneumonia. In addition, alveolar OSM levels correlated with the number of PMN obtained by BAL, suggesting that PMN are an important source of OSM within the alveoli. Indeed, purified alveolar PMN from all of the patients, especially those with pneumonia, strongly produced OSM. Interestingly, in the latter patients, alveolar PMN always produced more OSM than autologous blood PMN. These results document the functional duality of PMN in ALI by showing the participation of PMN in the modulation of lung inflammation.

Problem pathogens (Pseudomonas aeruginosa and Acinetobacter)

A number of factors have been suspected of or identified as increasing the risk for pneumonia or colonization of the lower respiratory tract by Pseudomonas and/or Acinetobacter spp. in the intensive care unit (ICU), including advanced age, chronic lung disease, immunosuppression, surgery, use of antimicrobial agents, presence of such invasive devices as endotracheal and gastric tubes, and type of respiratory equipment. However, there is little doubt that of all these factors, extended ICU care because of severe underlying disease, prolonged respiratory therapy with mechanical ventilation, and prior antimicrobial therapy are the most important. Because the only factor amenable to prevention in this setting is antimicrobial therapy, avoiding unnecessary antibiotics should be a high priority in the management of such patients. Crude mortality rates of 30% to 75% have been reported for nosocomial pneumonia caused by Pseudomonas and/or Acinetobacter spp., with the highest rates reported in ventilator-dependent patients. It is therefore clear that the prognosis associated with this type of infection is considerably worse than that associated with infection caused by other gram-negative or gram-positive bacteria. Because bactericidal synergy against Pseudomonas and Acinetobacter spp. has been shown when carbenicillin and an aminoglycoside are combined, the use of an effective beta-lactam (piperacillin, ticarcillin, ceftazidime, or imipenem) and aminoglycoside combination remains the preferred therapeutic approach when possible. Future research efforts should also aim to improve our ability to diagnose and exclude infection in the ICU setting to avoid administering unnecessary antibiotics to patients without true pulmonary infection.

Multicenter prospective study of ventilator-associated pneumonia during acute respiratory distress syndrome. Incidence, prognosis, and risk factors. ARDS Study Group

We investigated the incidence, risk factors for, and outcome of ventilator-associated pneumonia (VAP) in patients with acute respiratory distress syndrome (ARDS). We compared 134 patients with ARDS with 744 patients without ARDS on mechanical ventilation. Fiberoptic bronchoscopic examination and quantitative bacterial cultures (protected brush or catheter sampling [threshold: 10(3) cfu/ml], or bronchoalveolar lavage [threshold: 10(4) cfu/ml]) were used to diagnose pneumonia. VAP occurred in 49 patients (36.5%). The incidence of pneumonia was 23% (173 of 744 patients) among patients without ARDS (p < 0.002). Nonfermenting gram-negative rods caused significantly more pneumonia in ARDS patients. Mortality rates were identical in ARDS patients with (28 of 49 patients, 57%) and without (50 of 85 patients, 59%) pulmonary infection (p = 0.8). VAP resulted in a considerable increase in attributable time on mechanical ventilation of both the overall population of ARDS patients and of survivors. Both the use of sucralfate (adjusted odds ratio [OR]: 4. 42; 95% confidence interval [CI]: 2.01 to 9.7, p = 0.0002) and the duration of exposure to sucralfate (adjusted OR: 1.206; 95% CI: 1. 095 to 1.328, p = 0.0002) were associated with an increased risk of VAP during ARDS. VAP considerably prolongs the time on mechanical ventilation without affecting survival. Patients given sucralfate may be at greater risk of developing pulmonary infection during ARDS.

Invasive and noninvasive strategies for management of suspected ventilator-associated pneumonia. A randomized trial

BACKGROUND

Optimal management of patients who are clinically suspected of having ventilator-associated pneumonia remains open to debate.

OBJECTIVE

To evaluate the effect on clinical outcome and antibiotic use of two strategies to diagnose ventilator-associated pneumonia and select initial treatment for this condition.

DESIGN

Multicenter, randomized, uncontrolled trial.

SETTING

31 intensive care units in France.

PATIENTS

413 patients suspected of having ventilator-associated pneumonia.

INTERVENTION

The invasive management strategy was based on direct examination of bronchoscopic protected specimen brush samples or bronchoalveolar lavage samples and their quantitative cultures. The noninvasive ("clinical") management strategy was based on clinical criteria, isolation of microorganisms by nonquantitative analysis of endotracheal aspirates, and clinical practice guidelines.

MEASUREMENTS

Death from any cause, quantification of organ failure, and antibiotic use at 14 and 28 days.

RESULTS

Compared with patients who received clinical management, patients who received invasive management had reduced mortality at day 14 (16.2% and 25.8%; difference, -9.6 percentage points [95% CI, -17.4 to -1.8 percentage points]; P = 0.022), decreased mean Sepsis-related Organ Failure Assessment scores at day 3 (6.1+/-4.0 and 7.0+/-4.3; P = 0.033) and day 7 (4.9+/-4.0 and 5.8+/-4.4; P = 0.043), and decreased antibiotic use (mean number of antibiotic-free days, 5.0+/-5.1 and 2.2+/-3.5; P < 0.001). At 28 days, the invasive management group had significantly more antibiotic-free days (11.5+/-9.0 compared with 7.5+/-7.6; P < 0.001), and only multivariate analysis showed a significant difference in mortality (hazard ratio, 1.54 [CI, 1.10 to 2.16]; P = 0.01).

CONCLUSIONS

Compared with a noninvasive management strategy, an invasive management strategy was significantly associated with fewer deaths at 14 days, earlier attenuation of organ dysfunction, and less antibiotic use in patients suspected of having ventilator-associated pneumonia.

Prevalence, etiologies and outcome of the acute respiratory distress syndrome among hypoxemic ventilated patients. SRLF Collaborative Group on Mechanical Ventilation. Société de Réanimation de Langue Française

OBJECTIVE

To evaluate the prevalence and outcome of the acute respiratory distress syndrome (ARDS) among patients requiring mechanical ventilation.

DESIGN

A prospective, multi-institutional, initial cohort study including 28-day follow-up.

SETTINGS

Thirty-six French intensive care units (ICUs) from a working group of the French Intensive Care Society (SRLF).

PATIENTS

All the patients entering the ICUs during a 14-day period were screened prospectively. Hypoxemic patients, defined as having a PaO(2)/FIO(2) ratio (P/F) of 300 mmHg or less and receiving mechanical ventilation, were classified into three groups, according to the Consensus Conference on ARDS: group 1 refers to ARDS (P/F: 200 mmHg or less and bilateral infiltrates on the chest X-ray); group 2 to acute lung injury (ALI) without having criteria for ARDS (200 < P/F </= 300 mmHg and bilateral infiltrates) and group 3 to patients with P/F of 300 mmHg or less but having exclusion criteria from the previous groups.

RESULTS

Nine hundred seventy-six patients entered the ICUs during the study period, 43 % of them being mechanically ventilated and 213 (22 %) meeting the criteria for one of the three groups. Among all the ICU admissions, ARDS, ALI and group 3 patients amounted, respectively, to 6.9 % (67), 1.8 % (17) and 13.3 % (129) of the patients, and represented 31.5 %, 8.1 % and 60.2 % of the hypoxemic, ventilated patients. The overall mortality rate was 41 % and was significantly higher in ARDS patients than in the others (60 % vs 31 % p < 0.01). In group 3, 42 patients had P/F less than 200 mmHg associated with unilateral lung injury; mortality was significantly lower (40.5 %) than in the ARDS group. In the whole group of hypoxemic, ventilated patients, septic shock and severity indices but not oxygenation indices were significantly associated with mortality, while the association with immunosuppression revealed only a trend (p = 0.06).

CONCLUSIONS

In this survey we found that very few patients fulfilled the ALI non-ARDS criteria and that the mortality of the group with ARDS was high.

Tidal volume reduction for prevention of ventilator-induced lung injury in acute respiratory distress syndrome. The Multicenter Trail Group on Tidal Volume reduction in ARDS

Because animal studies have demonstrated that mechanical ventilation at high volume and pressure can be deleterious to the lungs, limitation of airway pressure, allowing hypercapnia if necessary, is already used for ventilation of acute respiratory distress syndrome (ARDS). Whether a systematic and more drastic reduction is necessary is debatable. A multicenter randomized study was undertaken to compare a strategy aimed at limiting the end-inspiratory plateau pressure to 25 cm H2O, using tidal volume (VT) below 10 ml/kg of body weight, versus a more conventional ventilatory approach (with regard to current practice) using VT at 10 ml/kg or above and close to normal PaCO2. Both arms used a similar level of positive end-expiratory pressure. A total of 116 patients with ARDS and no organ failure other than the lung were enrolled over 32 mo in 25 centers. The two groups were similar at inclusion. Patients in the two arms were ventilated with different VT (7.1 +/- 1.3 versus 10.3 +/- 1.7 ml/kg at Day 1, p < 0.001) and plateau pressures (25.7 +/- 5. 0 versus 31.7 +/- 6.6 cm H2O at Day 1, p < 0.001), resulting in different PaCO2 (59.5 +/- 15.0 versus 41.3 +/- 7.6 mm Hg, p < 0.001) and pH (7.28 +/- 0.09 versus 7.4 +/- 0.09, p < 0.001), but a similar level of oxygenation. The new approach did not reduce mortality at Day 60 (46.6% versus 37.9% in control subjects, p = 0.38), the duration of mechanical ventilation (23.1 +/- 20.2 versus 21.4 +/- 16. 3 d, p = 0.85), the incidence of pneumothorax (14% versus 12%, p = 0. 78), or the secondary occurrence of multiple organ failure (41% versus 41%, p = 1). We conclude that no benefit could be observed with reduced VT titrated to reach plateau pressures around 25 cm H2O compared with a more conventional approach in which normocapnia was achieved with plateau pressures already below 35 cm H2O.

Nosocomial pneumonia in patients with acute respiratory distress syndrome

To describe the epidemiologic and microbial aspects of ventilator-associated pneumonia (VAP) in patients with acute respiratory distress syndrome (ARDS), we prospectively evaluated 243 consecutive patients who required mechanical ventilation (MV) for > or = 48 h, 56 of whom developed ARDS as defined by a Murray lung injury score > 2.5. We did this with bronchoscopic techniques when VAP was clinically suspected, before any modification of existing antimicrobial therapy. For all patients, the diagnosis of pneumonia was established on the basis of culture results of protected-specimen brush (PSB) (> or = 10(3) cfu/ml) and bronchoalvelolar lavage fluid (BALF) (> or = 10(4) cfu/ml) specimens, and direct examination of cells recovered by bronchoalveolar lavage (BAL) (< or = 5% of infected cells). Thirty-one (55%) of the 56 patients with ARDS developed VAP for a total of 41 episodes, as compared with only 53 (28%) of the 187 patients without ARDS for a total of 65 episodes (p = 0.0005). Only 10% of first episodes of VAP in patients with ARDS occurred before Day 7 of MV, as compared with 40% of the episodes in patients without ARDS (p = 0.005). All but two patients with ARDS who developed VAP had received antimicrobial treatment (mostly with broad-spectrum antibiotics) before the onset of infection, as compared with only 35 patients without ARDS (p = 0.004). The organisms most frequently isolated from patients with ARDS and VAP were methicillin-resistant Staphylococcus aureus (23%), nonfermenting gram-negative bacilli (21%), and Enterobacteriaceae (21%). These findings confirm that microbiologically provable VAP occurs far more often in patients with ARDS than in other ventilated patients. Because these patients are often treated with antibiotics early in the course of the syndrome, the onset of VAP is frequently delayed after the first week of MV, and is then caused mainly by methicillin-resistant S. aureus and other multiresistant microorganisms.

Ventilator-associated pneumonia caused by potentially drug-resistant bacteria

To determine risk factors for ventilator-associated pneumonia (VAP) caused by potentially drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and/or Stenotrophomonas maltophilia, 135 consecutive episodes of VAP observed in a single ICU over a 25-mo period were prospectively studied. For all patients, VAP was diagnosed based on results of bronchoscopic protected specimen brush (> or = 10(3) cfu/ml) and bronchoalveolar lavage (> or = 10(4) cfu/ml) specimens. Seventy-seven episodes were caused by "potentially resistant" bacteria and 58 episodes were caused by "other" organisms. According to logistic regression analysis, three variables among potential factors remained significant: duration of mechanical ventilation (MV) > or = 7 d (odds ratio [OR] = 6.0), prior antibiotic use (OR = 13.5), and prior use of broad-spectrum drugs (third-generation cephalosporin, fluoroquinolone, and/or imipenem) (OR = 4.1). Distribution of the 245 causative bacteria was analyzed according to four groups defined by prior duration of MV (< 7 or > or = 7 d) and prior use or lack of use (within 15 d) of antibiotics. Although 22 episodes of early-onset VAP in patients receiving no prior antibiotics were caused by antibiotic-susceptible bacteria, 84 episodes of late-onset VAP in patients receiving prior antibiotics were mainly caused by potentially resistant bacteria. Differences in the potential efficacies (ranging from 100% to 11%) against microorganisms of 15 antimicrobial regimens were studied according to classification into these four groups. These findings may provide a more rational basis for selecting the initial therapy of patients suspected of having VAP.

Usefulness of quantitative cultures of BAL fluid for diagnosing nosocomial pneumonia in ventilated patients

STUDY OBJECTIVE

To evaluate the role of quantitative cultures of BAL for diagnosing nosocomial pneumonia in mechanically ventilated patients.

DESIGN

Cohort study.

SETTING

Medical ICU, Hôpital Bichat, Paris, France, an academic tertiary care center.

PATIENTS

A total of 141 episodes of suspected lung infection in 84 consecutive patients mechanically ventilated for 48 h or more.

MEASUREMENTS AND RESULTS

Microbiologic findings obtained using BAL were compared with those obtained with protected specimen brush (PSB) samples and their operating characteristics were determined. The level of qualitative agreement between BAL and PSB specimen cultures was high, with 83% of the organisms isolated in PSB specimens being recovered simultaneously from BAL fluid. In addition, the results of quantitative BAL and PSB cultures were significantly correlated (rho = 0.46, p < 0.0001). Fifty-seven cases of pneumonia were diagnosed based on the following criteria: PSB sample yielding > or = 10(3) cfu/mL of at least one microorganism and/or > or = 5% of cells containing intracellular bacteria on direct examination of BAL. The operating characteristics of BAL fluid cultures were determined using different ways to report the results and over a range of values. The discriminative value of 10(4) cfu/mL was found to be an optimal threshold, with a sensitivity of 82% (95% confidence interval [CI], 76 to 88) and a specificity of 84.5% (95% CI, 79 to 90).

CONCLUSIONS

These results indicate that BAL fluid cultures can offer a sensitive and specific means to diagnose pneumonia in ventilated patients and may provide relevant information about the causative pathogens.

[Nosocomial pneumonia in intensive care units]

Nosocomial pneumonia is associated with substantial morbidity and mortality. Patients treated with mechanical ventilation have the highest risk for developing this intensive care unit acquired infection. Gram-negative bacilli are the predominant organisms responsible for pneumonia in this setting. However, Staphylococcus aureus has recently emerged as a significant isolate. Nosocomial pneumonia is difficult to diagnose clinically in ventilated patients because fever, lung infiltrate on chest X-ray, leukocytosis are frequent in severely ill patients under mechanical ventilation whatever lung infection is present or not and because lower respiratory tract of such patients is colonized by potentially pathogenic bacteria independently of the presence of true lung infection; thus, different diagnostic strategies are proposed. Our personal bias is that using bronchoscopic techniques to obtain bronchoalveolar lavage and protected-brush specimens permits us to devise a therapeutic strategy that is superior to one based only on clinical evaluation. Measures for prevention of nosocomial infection are essential to decrease the incidence of nosocomial pneumonia and the emergence of multiresistant pathogens.

Long-term outcome and quality of life of patients requiring multidisciplinary intensive care unit admission after cardiac operations

Patients with organ failure or severe infection after cardiac operations may require prolonged stays in the intensive care unit. This study examined long-term mortality and determined quality of life for surviving patients in this group. This observational cohort study was conducted at Bichat Hospital, Paris, an academic tertiary care center. The study group consisted of 116 consecutive patients who underwent cardiac operations and were transferred to the multidisciplinary intensive care unit between January 1986 and December 1987. Patients referred for mediastinitis were automatically excluded. Respiratory failure (88.8%) and hemodynamic instability (81.9%) were the main causes of transfer; an infection was present in 23.3% of patients at entry into the intensive care unit. Twenty-seven patients (23.3%) died in the intensive care unit. Presurgical New York Heart Association functional class, postoperative bacteremia before admission to the intensive care unit, and severity of illness on admission to the intensive care unit were independent predictors of death in the intensive care unit. After an average follow-up of 81 months (range 70 to 93 months), 69% of the patients alive at transfer from the intensive care unit were still alive. Preoperative New York Heart Association functional class was the only long-term independent prognostic factor. Quality of life, as evaluated by the Nottingham Health Profile, was good for more than 70% of the survivors and was not influenced by any recorded variables, with the exception of age.

Interactions between neutrophils and cytokines in blood and alveolar spaces during ARDS

Although the pathogenesis of the acute respiratory distress syndrome (ARDS) is complex and poorly understood, several observations point to an important role of interactions between polymorphonuclear neutrophils (PMN) and cytokines in this process. We therefore studied certain parameters involved in PMN transendothelial migration (adhesion molecule expression and cytoskeletal organization) in patients with ARDS (n = 14) in comparison with other ventilated patients (n = 15). We found that in the basal state, both whole-blood PMN and alveolar PMN obtained by bronchoalveolar lavage (BAL) were activated, as shown by decreased L-selectin CD62L and increased beta 2 integrin CD11b expression, as well as decreased F-actin content. The degree of PMN activation increased with the degree of lung injury and with the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-8 (IL-8). Moreover, the capacity of ex vivo stimulation of alveolar PMN by a bacterial peptide was low in ARDS and could partly account for the high susceptibility of these patients to lung infection. Therefore, ARDS-associated lung injury could be caused, at least in part, by inappropriate adhesion and transendothelial migration of proinflammatory cytokine-primed PMN.

Mortality due to ventilator-associated pneumonia or colonization with Pseudomonas or Acinetobacter species: assessment by quantitative culture of samples obtained by a protected specimen brush

Ventilator-associated pneumonia (VAP) due to multiresistant pathogens is associated with a high death rate. We analyzed the relationship between VAP due to Pseudomonas or Acinetobacter species and death by comparing the outcomes for patients colonized with these pathogens (bacterial counts of < 10(3) cfu/mL) with those for patients with pneumonia due to these pathogens (bacterial counts of > or = 10(3) cfu/mL). Samples were obtained systematically with a protected specimen brush when pneumonia was suspected. Clinical characteristics at admission to our intensive care unit and clinical features at the time of suspicion of VAP were not significantly different between colonized patients and those with VAP. Mortality rates were 29% among colonized patients and 73% among patients with VAP (P < .001). These results demonstrate a relationship between a high mortality rate and the development of pneumonia due to multiresistant, nonfermenting, gram-negative bacilli ( > or = 10(3) cfu/mL) in the lower airways of patients receiving ventilatory support.

Diagnosis of pulmonary infections in mechanically ventilated patients

The optimal management strategy for ventilator-dependent patients who develop symptoms suggestive of lung infection remains controversial. Proponents of the empirical approach prefer to treat most patients with fever and pulmonary infiltrates with one or more new antibiotics, even if it may be difficult (1) to determine whether pneumonia has developed in such patients, (2) in case of infection, to precisely identify the responsible microorganisms and thereby select the optimal antimicrobial treatment, and (3) to avoid resorting to broad-spectrum drug coverage in patients without true infection. Our personal bias is that using bronchoscopic techniques to obtain protected specimen brush and bronchoalveolar lavage specimens from the affected area in the lung permits to devise a therapeutic strategy superior to the one based only on clinical evaluation. These bronchoscopic techniques, when they are performed before new antibiotics are administered, enable physicians to identify most patients who need immediate treatment and select optimal therapy, in a manner that is safe and well tolerated by patients. Furthermore, they frequently permit the clinician to withhold antimicrobial treatment in patients without infection, minimizing the risk of the emergence of resistant microorganisms in the intensive care unit. In patients with clinical evidence of severe sepsis, the initiation of antibiotic therapy should not, however, be delayed while awaiting bronchoscopy, and patients should be given immediate treatment with antibiotics. In that case, "simplified" non-bronchoscopic diagnostic procedures might allow obtaining reliable distal pulmonary secretions for quantitative cultures on a 24-hour basis just before the initiation of a new antimicrobial therapy.

Severe exacerbations of COPD patients: the role of pulmonary infections

Infection is usually considered the main cause of acute exacerbation in chronic obstructive pulmonary disease (COPD). However, uncertainty persists concerning the exact role of bacterial and viral infection in this setting because of the confusing and conflicting data on the role of tracheobronchial microflora and the usefulness of antibiotics in treating this disease. Most COPD patients have evidence of lower respiratory tract chronic bacterial colonization during remission periods as well as during acute exacerbations. This is evidenced by using microbiological analysis of secretions, which reflect all the respiratory tract (sputum), the lower respiratory tract (transtracheal aspiration), or the distal respiratory tract (protected specimen brush). Potentially pathogenic organisms can be recovered from the respiratory tract secretions of virtually all patients with COPD at some time during the course of their disease. Absence of difference in isolation of potentially pathogenic organisms between remission periods and acute exacerbations suggests that bacterial infection is probably not the predominant cause of acute exacerbations in COPD. In contrast, data indicate that the association between viral infections and acute exacerbations is clearer than that with bacteria, affecting probably more than 20% of cases. The role of antibiotic therapy in acute exacerbations of COPD remains controversial. (1) Clearly, antibiotic therapy is urgently required in COPD patients with pneumonia. (2) Review of the conflicting results of studies evaluating the role of antibiotic therapy for preventing acute exacerbations suggests that there is no clear-cut rationale for prophylactic treatment of infection for all patients with COPD; it seems, however, that such treatment may be of some use in highly selected patients, such as those with many exacerbations in the winter. (3) Similarly, data are conflicting concerning the curative use of antibiotic therapy, with some studies suggesting acceleration of recovery, prevention of acute deterioration, and longer period of freedom from recurrent exacerbations; conversely many patients recover from exacerbations without resorting to an antibiotic. Unfortunately, no clear data identify patients who could benefit from antibiotic treatment, probably justifying most clinicians' choice to treat acute exacerbations as infectious events.

Nosocomial pneumonia and mortality among patients in intensive care units

OBJECTIVE

To evaluate the role that nosocomial pneumonia plays in the outcome of intensive care unit (ICU) patients.

DESIGN

Cohort study.

SETTING

Medical ICU, Hôpital Bichat, Paris, France, an academic tertiary care center.

PATIENTS

A total of 1978 consecutive patients admitted to the ICU for at least 48 hours.

MAIN OUTCOME MEASURES

Various parameters known to be strongly associated with death of ICU patients were recorded: age, location before admission to the ICU, diagnostic categories, Acute Physiology and Chronic Health Evaluation (APACHE) II score, Simplified Acute Physiologic Score, McCabe score, number and type of dysfunctional organs, and the development of nosocomial bacteremia and nosocomial urinary tract infection. These variables and the presence or absence of nosocomial pneumonia were compared between survivors and nonsurvivors and entered into a stepwise logistic regression model to evaluate their independent prognostic roles.

RESULTS

Nosocomial pneumonia developed in 328 patients (16.6%) whose mortality was 52.4% compared with 22.4% for patients without ICU-acquired pneumonia (P < .001), APACHE II score (odds ratio [OR] = 1.08; 95% confidence interval [CI], 1.06 to 1.10; P < .001), number of dysfunctional organs (OR = 1.54; 95% CI, 1.36 to 1.74; P < .001), nosocomial pneumonia (OR = 2.08; 95% CI, 1.55 to 2.80; P < .001), nosocomial bacteremia (OR = 2.51; 95% CI, 1.78 to 3.55; P < .001), ultimately or rapidly fatal underlying disease (OR = 1.76; 95% CI, 1.38 to 2.25; P < .001), and admission from another ICU (OR = 1.30; 95% CI, 1.01 to 1.68; P =.04) were significantly associated with mortality.

CONCLUSION

These data suggest that, in addition to the severity of underlying medical conditions and nosocomial bacteremia, nosocomial pneumonia independently contributes to ICU patient mortality.

Closed drainage using Redon catheters for local treatment of poststernotomy mediastinitis

BACKGROUND

Continuous irrigation has been used worldwide for the treatment of acute poststernotomy mediastinitis. However, its high rate of failure led to the development of new methods, among them closed drainage with Redon catheters.

METHODS

We evaluated the results obtained with Redon catheters in 70 patients, and compared them to those obtained in 38 patients treated with continuous irrigation.

RESULTS

The two treatment groups were not different for age, type of cardiac operation, and initial severity of illness. Local failure of Redon catheter drainage occurred less frequently (20 of 38 versus 9 of 70 patients; p = 0.0001). This reduced failure rate was mainly attributable to a lower incidence of superinfections (10 of 38 versus 2 of 70 patients; p = 0.0002), but also to a lower incidence of primary failure (10 of 38 versus 7 of 70 patients; p = 0.026). Mortality was significantly decreased (15 of 38 versus 12 of 70 patients; p = 0.01). The other major advantage of this technique was the simplicity of its use.

CONCLUSIONS

The technique using Redon catheters should be considered an effective and convenient treatment of acute poststernotomy mediastinitis.