Diagnosis and treatment of ventilator-associated pneumonia--impact on survival. A decision analysis

The Effect of Blind-Protected Specimen Brush Sampling on Antibiotic Use in Patients with Suspected Ventilator-Associated Pneumonia

The diagnosis of pneumonia in ventilated patients is exceedingly difficult. Although culture of tracheal aspirates have poor diagnostic value they are frequently used to diagnose ventilator-associated pneumonia (VAP). Recently a number of studies have reported on the diagnostic value of “blind” protected specimen brush (B-PSB) sampling in the diagnosis of VAP. B-PSB sampling can readily and safely be performed by respiratory care practitioners (RCPs). The aim of this study was to determine the cost-effectiveness of B-PSB sampling performed by respiratory therapists in patients with suspected VAP. During a 3-month run-in period, patients in our medical intensive care unit (MICU) with suspected VAP were treated based on clinical criteria and tracheal aspirate culture. Following this run-in period the house staff, nurses, and RCPs were prevented from sending tracheal aspirates for culture. All patients suspected of having VAP underwent B-PSB sampling with quantitative culture. The B-PSB sampling was performed by RCPs who had been trained to perform the technique. A PSB with a potential bacterial pathogen concentration greater than 500 CFU/ml was regarded as positive. During the 3-month run-in period 172 patients received mechanical ventilation with an average of 4.9 ±3.1 ventilator days/patient. During this period 79 patients were treated for VAP. During the 3-month study period 160 patients received mechanical ventilation, with an average of 5.1 ± 2.9 ventilator days/patient (NS). Fifty-eight B-PSB samplings were performed in 50 patients for suspected VAP. No complications related to the procedure were reported. No tracheal aspirates were cultured during this time period. Eight patients had positive PSB cultures. Antibiotics were changed in three of these patients based on the PSB results. Thirty-eight courses of antibiotics (in 36 patients) were stopped based on negative PSB results. Twelve cases of VAP were suspected in six patients receiving antibiotics for other reasons. No change in antibiotics were made in these cases based on the negative PSB results. The length of mechanical ventilation was 5.4 ± 3.2 days in the 38 culture-negative patients in whom antibiotics were stopped compared to 8.2 ± 4.7 days in the 8 patients with PSB-positive VAP (NS; p = 0.14). The direct cost savings as a result of discontinuing antibiotics was $9,500. There were additional cost savings due to the reduced number of culture specimens sent to the laboratory (approximately $3,000; taking the $23 cost of the PSB brush into account), with a projected annual cost savings of $50,000. B-PSB sampling is a simple and cost-efficient diagnostic test that can safely be performed by adequately trained RCPs. Furthermore, this study confirms that antibiotics may be safely discontinued in patients with negative quantitative culture results.

Management of Adults With Hospital-acquired and Ventilator-associated Pneumonia: 2016 Clinical Practice Guidelines by the Infectious Diseases Society of America and the American Thoracic Society

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.These guidelines are intended for use by healthcare professionals who care for patients at risk for hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), including specialists in infectious diseases, pulmonary diseases, critical care, and surgeons, anesthesiologists, hospitalists, and any clinicians and healthcare providers caring for hospitalized patients with nosocomial pneumonia. The panel's recommendations for the diagnosis and treatment of HAP and VAP are based upon evidence derived from topic-specific systematic literature reviews.

Agreement of decision analyses and subsequent clinical studies in infectious diseases

PURPOSE

Decision analysis techniques can compare management strategies when there are insufficient data from clinical studies to guide decision making. We compared the outcomes of decision analyses and subsequent clinical studies in the infectious disease literature to assess the validity of the conclusions of the decision analyses.

METHODS

A search strategy to identify decision analyses in infectious disease topics published from 1990 to 2005 was developed and performed using PubMed. Abstracts of all identified articles were reviewed, and infectious disease-related decision analyses were retained. Subsequent clinical trials and observational studies that corresponded to these decision analyses were identified using prespecified search strategies. Clinical studies were considered a match for the decision analysis if they assessed the same patient population, intervention, and outcome. Agreement or disagreement between the conclusions of the decision analysis and clinical study were determined by author review.

RESULTS

The initial PubMed search yielded 318 references. Forty decision analyses pertaining to 29 infectious disease topics were identified. Of the 40, 16 (40%) from 13 infectious disease topics had matching clinical studies. In 12 of 16 (75%), conclusions of at least 1 clinical study agreed with those of the decision analysis. Three of the 4 decision analyses in which conclusions disagreed were from the same topic (management of febrile children).

CONCLUSIONS

There was substantial agreement between the conclusions of decision analyses and clinical studies in infectious diseases, supporting the validity of decision analysis and its utility in guiding management decisions.

Ventilator-associated pneumonia: diagnosis, treatment, and prevention

While critically ill patients experience a life-threatening illness, they commonly contract ventilator-associated pneumonia. This nosocomial infection increases morbidity and likely mortality as well as the cost of health care. This article reviews the literature with regard to diagnosis, treatment, and prevention. It provides conclusions that can be implemented in practice as well as an algorithm for the bedside clinician and also focuses on the controversies with regard to diagnostic tools and approaches, treatment plans, and prevention strategies.

Use of quantitative cultures and reduced duration of antibiotic regimens for patients with ventilator-associated pneumonia to decrease resistance in the intensive care unit

Ventilator-associated pneumonia is responsible for approximately half of the infections acquired in the intensive care unit and represents one of the principal reasons for the prescription of antibiotics in this setting. Invasive diagnostic methods, including bronchoalveolar lavage and/or protected specimen bronchial brushing, could improve the identification of patients with true bacterial pneumonia and facilitate decisions of whether to treat. These techniques also permit rapid optimization of the choice of antibiotics in patients with proven bacterial infection, once the results of respiratory tract cultures become available, based on the identity of the specific pathogens and their susceptibility to specific antibiotics, to avoid prolonged use of a broader spectrum of antibiotic therapy than is justified by the available information. Because unnecessary prolongation of antibiotic therapy for patients with true bacterial infection may lead to the selection of multidrug-resistant microorganisms without improving clinical outcome, efforts to reduce the duration of therapy for nosocomial infections are also warranted. An 8-day regimen can probably be standard for patients with ventilator-associated pneumonia. Possible exceptions to this recommendation include immunosuppressed patients, patients who are bacteremic or whose initial antibiotic therapy was not appropriate for the causative microorganism(s), and patients whose infection is with very difficult-to-treat microorganisms and show no improvement in clinical signs of infection.

Nosocomial pneumonia in elderly patients following cardiac surgery

OBJECTIVE

To identify modifiable risk factors of nosocomial pneumonia (NP) in elderly patients post-cardiac surgery.

DESIGN

A case-control study.

SETTING

Post-operative intensive care unit of a tertiary-level university affiliated hospital.

SUBJECTS

Seventy three case-control pairs. Case patients referred to elderly patients who developed pneumonia post-cardiac surgery. Controls subjects were matched for age, gender, type of surgery, forced expiratory volume in 1s (FEV(1)), and ejection fraction.

MEASUREMENTS

Baseline sociodemograpahic information, Charlson Comorbidity Index score, intra- and post-operative data were collected. When suspected, the presence of NP was confirmed by quantitative culture of protected bronchoalveolar lavage fluid 10(3) colony forming unit/ml or positive blood/pleural fluid culture identical to that recovered from respiratory samples.

RESULTS

The incidence of NP in elderly post-heart surgery was 8.3%. The mean duration after heart surgery to the occurrence of pneumonia was 7.2+/-4.9 days. Four variables were found to be significantly related to the development of NP by multivariate analysis: Charlson Index >2 (adjusted odds ratio [AOR] 4.7; 95% confidence interval [CI], 1.9-11.4; P<0.001), reintubation (AOR 6.2; 95% CI, 1.1-36.1; P=0.04), transfusion 4 units of PRBC (AOR 2.8; 95% CI, 1.2-6.3; P=0.01), and the mean equivalent daily dose of morphine (AOR 4.6; 95% CI, 1.4-14.6; P=0.01).

CONCLUSIONS

Although there are limited effective measures to lessen the burden of comorbidities, avoiding reintubation, finding a substitute to allogenic blood transfusion, and improved assessment of pain management could reduce the rate of NP in the post-operative period of cardiac surgery in the elderly population.

Ventilator-associated pulmonary infection: the germ theory of disease remains viable

Pulmonary infection complicating mechanical ventilation is a major problem in critical care. The key issues surrounding care of patients suspected of having this disease are 1) appropriate diagnostic criteria; 2) when antibiotic therapy should be started; and 3) what constitutes adequate antibiotic therapy. Current data support use of quantitative cultures obtained by either bronchoscopic or blind catheter lavage or mini-brushing. Antibiotic therapy should be guided by duration of hospitalization prior to presumed infection and local predominating nosocomial organisms and their microbial resistance patterns. The key issue with timing of therapy now centers around early termination of therapy if quantitative cultures are negative.

Diagnosis of infection in sepsis: An evidence-based review

OBJECTIVE

In 2003, critical care and infectious disease experts representing 11 international organizations developed management guidelines for the diagnosis of infection in sepsis that would be of practical use for the bedside clinician, under the auspices of the Surviving Sepsis Campaign, an international effort to increase awareness and improve outcome in severe sepsis.

DESIGN

The process included a modified Delphi method, a consensus conference, several subsequent smaller meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee.

METHODS

The modified Delphi methodology used for grading recommendations built on a 2001 publication sponsored by the International Sepsis Forum. We undertook a systematic review of the literature graded along five levels to create recommendation grades from A to E, with A being the highest grade. Pediatric considerations to contrast adult and pediatric management are in the article by Parker et al. on p. S591.

CONCLUSIONS

Obtaining a precise bacteriological diagnosis before starting antibiotic therapy is, when possible, of paramount importance for the success of therapeutic strategy during sepsis. Two to three blood cultures should be performed, preferably from a peripheral vein, without interval between samples to avoid delaying therapy. A quantitative approach is preferred in most cases when possible, in particular for catheter-related infections and ventilator-associated pneumonia. Diagnosing community-acquired pneumonia is complex, and a diagnostic algorithm is proposed. Appropriate samples are indicated during soft tissue and intraabdominal infections, but cultures obtained through the drains are discouraged.

Decision analysis of antibiotic and diagnostic strategies in ventilator-associated pneumonia

The optimal strategy for ventilator-associated pneumonia remains controversial. To clarify the tradeoffs involved, we performed a decision analysis. Strategies evaluated included antibiotic therapy with and without diagnostic testing. Tests that were explored included endotracheal aspirates, bronchoscopy with protected brush or bronchoalveolar lavage, and nonbronchoscopic mini-bronchoalveolar lavage (mini-BAL). Outcomes included dollar cost, antibiotic use, survival, cost-effectiveness, antibiotic use per survivor, and the outcome perspective of financial cost-antibiotic use per survivor. Initial coverage with three antibiotics was better than expectant management or one or two antibiotic approaches, leading to both improved survival (54% vs. 66%) and decreased cost (US dollars 55447 vs. US dollars 41483 per survivor). Testing with mini-BAL did not improve survival but did decrease costs (US dollars 41483 vs. US dollars 39967) and antibiotic use (63 vs. 39 antibiotic days per survivor). From the perspective of minimizing cost, minimizing antibiotic use, and maximizing survival, the best strategy was three antibiotics with mini-BAL.

Correlation of intracellular organisms with quantitative endotracheal aspirate

BACKGROUND

The presence of intracellular organisms (ICOs) in polymorphonuclear cells obtained from respiratory secretions is a possible method for rapid diagnosis of ventilator-associated pneumonia. We correlated ICOs with quantitative endotracheal aspirate (QA) in intubated patients.

METHODS

Consecutive intubated patients in the surgical intensive care unit had respiratory samples obtained every 2 days until extubation. Two thresholds for ICOs and quantitative culture were examined. Sensitivity, specificity, and positive and negative predictive values were calculated using QA as reference.

RESULTS

One hundred one samples were obtained from 35 patients. Colony counts >or= 100,000 were found in 34 samples; 60 samples had colony counts >or= 10,000. Antibiotic use did not affect the sensitivity or specificity of ICOs. Sensitivity of ICOs was 39% to 85%, and specificity was 82% to 97%. Positive predictive value was 70% to 96%, and negative predictive value was 50% to 91%.

CONCLUSION

ICOs provide a quick method for establishing the presence of a significant bacterial load in the respiratory tract. Accuracy of ICOs in predicting a positive QA is not affected by concurrent antibiotics.

Ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) continues to complicate the course of 8 to 28% of patients receiving mechanical ventilation (MV). In contrast to infections of more frequently involved organs (e.g., urinary tract and skin), for which mortality is low, ranging from 1 to 4%, the mortality rate for VAP ranges from 24 to 50% and can reach 76% in some specific settings or when lung infection is caused by high-risk pathogens. The predominant organisms responsible for infection are Staphylococcus aureus, Pseudomonas aeruginosa, and Enterobacteriaceae, but etiologic agents widely differ according to the population of patients in an intensive care unit, duration of hospital stay, and prior antimicrobial therapy. Because appropriate antimicrobial treatment of patients with VAP significantly improves outcome, more rapid identification of infected patients and accurate selection of antimicrobial agents represent important clinical goals. Our personal bias is that using bronchoscopic techniques to obtain protected brush and bronchoalveolar lavage specimens from the affected area in the lung permits physicians to devise a therapeutic strategy that is superior to one based only on clinical evaluation. When fiberoptic bronchoscopy is not available to physicians treating patients clinically suspected of having VAP, we recommend using either a simplified nonbronchoscopic diagnostic procedure or following a strategy in which decisions regarding antibiotic therapy are based on a clinical score constructed from seven variables. Selection of the initial antimicrobial therapy should be based on predominant flora responsible for VAP at each institution, clinical setting, information provided by direct examination of pulmonary secretions, and intrinsic antibacterial activities of antimicrobial agents and their pharmacokinetic characteristics. Further trials will be needed to clarify the optimal duration of treatment and the circumstances in which monotherapy can be safely used.

Saturday night fever: finding and controlling the source of sepsis in critical illness

Fever is a daily concern in the intensive care unit. Although about half of all febrile cases are due to non-infectious causes, fear of sepsis frequently leads to diagnostic tests and escalation of therapy, including broadening antibiotic therapy. Using a case to illustrate this dilemma, we discuss the commonest non-infectious and infectious causes of fever, and suggests approaches to their management. Any unexplained fever in intensive care unit patients warrants investigation, which includes complete clinical assessment and blood cultures. When the source of fever is not immediately apparent, non-infectious and infectious causes should be considered. If stable, non-neutropenic patients should be monitored before further tests or empiric antibiotics are started. In an era of rapid emergence and spread of antimicrobial-resistant pathogens and intense scrutiny of resources, optimal diagnosis and management of patients with suspected infection entails much more than the escalation of antimicrobial therapy.

Controversies in the diagnosis of ventilator-acquired pneumonia

The appropriate investigation of patients with suspected VAP is controversial. Because it is unlikely that any new diagnostic technique will become available in the near future with better performance characteristics than those currently available, physicians need to tailor their diagnostic approach depending on individual patients and clinical scenarios. The most crucial factor in deciding which diagnostic approach to take is the influence that any test result would have on management. If preliminary screening tests, including Gram stain, are used to determine whether to start antibiotic therapy, invasive diagnostic techniques have an advantage over ETA. Quantitative cultures of respiratory specimens have a higher specificity than qualitative cultures and should be used if there is any possibility that a negative culture result would result in the discontinuation of antibiotic therapy. Physicians are caught between the need to treat VAP promptly with appropriate antibiotics and the undeniable problems of multidrug-resistant bacteria and their association with inappropriate antibiotic use. When clinically possible, a diagnostic strategy should be chosen that maximizes the possibility of limiting broad-spectrum antibiotic use. To give physicians greater comfort in the ability to withhold or discontinue antibiotics safely, further research is needed into the appropriate diagnostic strategies in different clinical settings that make this possible. The studies by Fagon et al and Singh et al are important steps in this direction.

Antibiotic therapy of ventilator-associated pneumonia--a reappraisal of rationale in the era of bacterial resistance

Ventilator-associated pneumonia (VAP) is the most frequent nosocomial infection in intensive care units (ICU). Resistance patterns seen in ICUs suggest that prescribing recommendations should be reappraised to limit practices engendering resistance to large families of antibiotics. Despite concern surrounding the use of antibiotics in the management of VAP, there is limited evidence to assist the clinician in making decisions about the indications for such therapy, the selection of the correct antibiotic(s), the timing of initiation of therapy and its duration. The high amount of antibiotic use, in combination with the low grade colonisation of patients with multi-resistant pathogens at the time of admission, turns the ICU into an environment where antibiotic policy is likely to have an effect on the resistance problem. Opinions are changing as to the validity of invasive techniques in guiding prescribing decisions. Invasive and semi-invasive diagnostic testing increases physician confidence in the diagnosis and management of VAP and helps to limit or discontinue antibiotic treatment.

Diagnostic investigation of ventilator-associated pneumonia using bronchoalveolar lavage: comparative study with a postmortem lung biopsy

The purpose of the present study was to validate the quantitative culture and cellularity of bronchoalveolar lavage (BAL) for the diagnosis of ventilator-associated pneumonia (VAP). A prospective validation test trial was carried out between 1992 and 1997 in a general adult intensive care unit of a teaching hospital. Thirty-seven patients on mechanical ventilation with suspected VAP who died at most three days after a BAL diagnostic procedure were submitted to a postmortem lung biopsy. BAL effluent was submitted to Gram staining, quantitative culture and cellularity count. Postmortem lung tissue quantitative culture and histopathological findings were considered to be the gold standard exams for VAP diagnosis. According to these criteria, 20 patients (54%) were diagnosed as having VAP and 17 (46%) as not having the condition. Quantitative culture of BAL effluent showed 90% sensitivity (18/20), 94.1% specificity (16/17), 94.7% positive predictive value and 88.8% negative predictive value. Fever and leukocytosis were useless for VAP diagnosis. Gram staining of BAL effluent was negative in 94.1% of the patients without VAP (16/17). Regarding the total cellularity of BAL, a cut-off point of 400,000 cells/ml showed a specificity of 94.1% (16/17), and a cut-off point of 50% of BAL neutrophils showed a sensitivity of 90% (19/20). In conclusion, BAL quantitative culture, Gram staining and cellularity might be useful in the diagnostic investigation of VAP.

Flexible bronchoscopy in nosocomial pneumonia

In this article, an overview on the diagnostic performances of bronchoscopic techniques for the diagnosis of nosocomial pneumonia is given with special emphasis on the inherent problems of the methodology of validation applied to different studies. The current evidence about the importance of bronchoscopic techniques for the outcome is reviewed. It is outlined that future prospects of bronchoscopic investigations mainly include the evaluation of its role in the reassessment of the patient with pneumonia not responding to the initial antimicrobial treatment.

An evaluation of the Gram stain in protected bronchoalveolar lavage fluid for the early diagnosis of ventilator-associated pneumonia

We investigated the usefulness and reliability of the Gram stain value versus quantitative cultures in the early diagnosis of ventilator-associated pneumonia (VAP) using the protected bronchoalveolar lavage (PBAL). One hundred four mechanically ventilated patients (age = 52 +/- 19; SAPS II = 38 +/- 15) with a strong suspicion of VAP were consecutively included. One hundred sixteen PBAL were performed and mini-bronchoalveolar lavage were analyzed using the Gram stain standard method and the conventional quantitative culture technique. VAP diagnosis was based on a positive quantitative culture of mini-bronchoalveolar lavage fluid (cutoff > or = 10(3) CFU/mL). A final diagnosis of VAP was established in 67 patients and there was no infection in 49 cases. Regarding detection of bacteria using the Gram stain, we found a sensitivity of 76.2%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 75.4%. There was a good agreement with the final diagnosis (kappa statistic 0.73; concordance 86.2%). The degree of qualitative agreement between Gram stain and quantitative cultures was analyzed in the VAP group: the correlation was complete in 39% (26 of 67 VAP), partial in 28% (19 of 67 VAP) and there was no correlation in 33% (22 of 67 VAP). We conclude that despite its overall "good agreement," the Gram stain is of limited use for the rapid diagnosis of VAP and unreliable for the early adaptation of empirical antimicrobial therapy when using the noninvasive PBAL procedure.

Impact of quantitative invasive diagnostic techniques in the management and outcome of mechanically ventilated patients with suspected pneumonia

OBJECTIVE

To assess how data obtained by invasive diagnostic techniques may affect management and outcome of patients with suspected ventilator-associated pneumonia (VAP), in comparison with noninvasive qualitative techniques.

DESIGN

Prospective study.

SETTING

An 18-bed medical and surgical intensive care unit.

PATIENTS

A total of 91 patients suspected of having VAP were randomized into two groups. In group A (n = 45), quantitative cultures obtained by either bronchoscopic or nonbronchoscopic techniques were performed, whereas in group B (n = 43), patients were treated based on clinical judgment and nonquantitative tracheal aspirates cultures. Three patients were excluded because of the absence of follow-up.

RESULTS

In patients with positive cultures, therapeutic changes were made in 20 patients. In four patients (three from group A and one from group B, p = NS), initial empirical antibiotic treatment was modified because the isolated microorganisms were not susceptible (all of them had late-onset pneumonia). The isolated organisms responsible for antibiotic modifications were methicillin-resistant Staphylococcus aureus (three patients) and Pseudomonas aeruginosa (one patient). In three patients, the antimicrobial therapy was considered inappropriate because the isolated microorganisms were multiresistant and treated with only one effective antibiotic. In 13 patients (ten from group A and three from group B, p < .05), treatment was changed to select a narrower spectrum antibiotic. No therapeutic modifications were made in patients with negative cultures based on the results of quantitative cultures. The overall mortality was 22.2% in group A and 20.9% in group B. There were no differences in intensive care unit stay or days of mechanical ventilation (23.67+/-3.15 vs. 22.42+/-3.01 and 19.99+/-2.88 vs. 19.24+/-3.04, respectively).

CONCLUSIONS

In our study population, the routine use of quantitative invasive diagnostic tools is not justified in the setting of ventilated patients clinically suspected of having nosocomial pneumonia.

Short-course empiric antibiotic therapy for patients with pulmonary infiltrates in the intensive care unit. A proposed solution for indiscriminate antibiotic prescription

Inappropriate antibiotic use for pulmonary infiltrates is common in the intensive care unit (ICU). We sought to devise an approach that would minimize unnecessary antibiotic use, recognizing that a gold standard for the diagnosis of nosocomial pneumonia does not exist. In a randomized trial, clinical pulmonary infection score (CPIS) (Pugin, J., R. Auckenthaler, N. Mili, J. P. Janssens, R. D. Lew, and P. M. Suter. Diagnosis of ventilator-associated pneumonia by bacteriologic analysis of bronchoscopic and nonbronchoscopic "blind" bronchoalveolar lavage fluid. Am. Rev. Respir. Dis. 1991;143: 1121-1129) was used as operational criteria for decision-making regarding antibiotic therapy. Patients with CPIS </= 6 (implying low likelihood of pneumonia) were randomized to receive either standard therapy (choice and duration of antibiotics at the discretion of physicians) or ciprofloxacin monotherapy with reevaluation at 3 d; ciprofloxacin was discontinued if CPIS remained </= 6 at 3 d. Antibiotics were continued beyond 3 d in 90% (38 of 42) of the patients in the standard as therapy compared with 28% (11 of 39) in the experimental therapy group (p = 0.0001). In patients in whom CPIS remained </= 6 at the 3 d evaluation point, antibiotics were still continued in 96% (24 of 25) in the standard therapy group but in 0% (0 of 25) of the patients in the experimental therapy group (p = 0.0001). Mortality and length of ICU stay did not differ despite a shorter duration (p = 0.0001) and lower cost (p = 0.003) of antimicrobial therapy in the experimental as compared with the standard therapy arm. Antimicrobial resistance, or superinfections, or both, developed in 15% (5 of 37) of the patients in the experimental versus 35% (14 of 37) of the patients in the standard therapy group (p = 0.017). Thus, overtreatment with antibiotics is widely prevalent, but unnecessary in most patients with pulmonary infiltrates in the ICU. The operational criteria used, regardless of the precise definition of pneumonia, accurately identified patients with pulmonary infiltrates for whom monotherapy with a short course of antibiotics was appropriate. Such an approach led to significantly lower antimicrobial therapy costs, antimicrobial resistance, and superinfections without adversely affecting the length of stay or mortality.

Noninvasive versus invasive microbial investigation in ventilator-associated pneumonia: evaluation of outcome

Noninvasive and invasive diagnostic techniques have been shown to achieve comparable performances in the evaluation of suspected ventilator-associated pneumonia (VAP). We studied the impact of both approaches on outcome in a prospective, open, and randomized study in three intensive care units (ICUs) of a 1,000-bed tertiary care university hospital. Patients with suspected VAP were randomly assigned to noninvasive (Group 1) versus invasive (Group 2) investigation (tracheobronchial aspirates [TBAS] versus bronchoscopically retrieved protected specimen brush [PSB] and bronchoalveolar lavage [BAL]. Samples were cultured quantitatively, and BAL fluid (BALF) was examined for intracellular organisms (ICO) additionally. Initial empiric antimicrobial treatment was administered following the guidelines of the American Thoracic Society (ATS) and adjusted according to culture results (and ICO counts in Group 2). Outcome variables included length of ICU stay and mechanical ventilation as well as mortality. Overall, 76 patients (39 noninvasive, 37 invasive) were investigated. VAP was microbiologically confirmed in 23 of 39 (59%) and 23 of 37 (62%) (p = 0.78). There were no differences with regard to the frequencies of community-acquired and potentially drug-resistant microorganisms (PDRM). Antimicrobial treatment was changed in seven patients (18%) of Group 1 and 10 patients (27%) of Group 2 because of etiologic findings (including five of 17 with ICO = 2% (p = not significant [NS]). Length of ICU stay and mechanical ventilation were also not significantly different in both groups. Crude 30-d mortality was 31 of 76 (41%), and 18 of 39 (46%) in Group 1 and 14 of 37 (38%) in Group 2 (p = 0.46). Adjusted mortality was 16% versus 11% (p = 0.53), and mortality of microbiologically confirmed pneumonia 10 of 23 (44%) in both groups (p = 1.0). We conclude that the outcome of VAP was not influenced by the techniques used for microbial investigation.

Rational empiric antibiotic prescription in the ICU

The prescribing of antibiotics in the ICU is usually empiric, given the critical nature of the conditions of patients hospitalized there. Appropriate antibiotic utilization in this setting is crucial not only in ensuring an optimal outcome, but in curtailing the emergence of resistance and containing costs. We propose that research in the ICUs is vitally important in guiding antibiotic prescription practices and, therefore, the achievement of above-stated goals. There is wide institutional diversity in the relative prevalence of predominant pathogens and their antimicrobial susceptibilities, and within individual ICUs there exist unique patient populations with varying risks for and susceptibilities to infections and specific pathogens. Appropriate antibiotic prescription practices should be formulated based on surveillance studies and research at individual ICUs; these goals can be accomplished utilizing existing resources.

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.

Comparison of direct examination of three types of bronchoscopy specimens used to diagnose nosocomial pneumonia

OBJECTIVE

To compare direct examination of bronchial aspirate and plugged telescopic catheter specimens (PTC) with infected cell counts in bronchoalveolar lavage (BAL) specimens for the diagnosis of nosocomial pneumonia.

DESIGN

Prospective study of critically ill patients.

SETTING

Intensive care unit in a university hospital.

PATIENTS

A total of 64 patients hospitalized for >48 hrs with suspected nosocomial pneumonia.

INTERVENTIONS

Fiberoptic bronchoscopy with bronchial aspirate and quantitative protected specimen brush, PTC, and BAL cultures. PTC and bronchial aspirate specimens were Gram-stained. BAL specimens for infected cell counts were examined as described previously in the literature.

MEASUREMENTS AND MAIN RESULTS

Nosocomial pneumonia was diagnosed by the medical staff based on all available clinical, radiologic, laboratory test, and microbiological data and on the course before and after appropriate therapy. A total of 71% of patients were ventilated, and 70.1% were receiving antibiotics. Nosocomial pneumonia was diagnosed in 54% of the cases. On direct examination, sensitivity (Se) and specificity (Sp) of bronchial aspirate specimens were Se, 82% and Sp, 60%; of BAL with 5% infected cells, Se, 56% and Sp, 100%; of BAL with 3% infected cells, Se, 74% and Sp, 96%; of PTC specimens, Se, 65% and Sp, 76%; and of PTC specimens plus BAL with 3% infected cells, Se, 83% and Sp, 78%. BAL with 3% infected cells was significantly better for predicting nosocomial pneumonia than direct examination of bronchial aspirate or PTC specimens (p = .0012). When the BAL showed 3% infected cells, neither direct examination of bronchial aspirate nor direct examination of PTC specimens was useful (p = .24 and p = .38, respectively). Combined use of direct examination of PTC specimens plus BAL with 3% infected cells markedly improved sensitivity. The total cost of each procedure was taken into account for the final evaluation.

CONCLUSIONS

Our data suggest that BAL with 3% infected cells is currently the only test whose predictive value for nosocomial pneumonia is sufficiently high to be of use for guiding the initial choice of antimicrobial class while waiting for quantitative culture results.

Fever in the ICU

Fever is a common problem in ICU patients. The presence of fever frequently results in the performance of diagnostic tests and procedures that significantly increase medical costs and expose the patient to unnecessary invasive diagnostic procedures and the inappropriate use of antibiotics. ICU patients frequently have multiple infectious and noninfectious causes of fever, necessitating a systematic and comprehensive diagnostic approach. Pneumonia, sinusitis, and blood stream infection are the most common infectious causes of fever. The urinary tract is unimportant in most ICU patients as a primary source of infection. Fever is a basic evolutionary response to infection, is an important host defense mechanism and, in the majority of patients, does not require treatment in itself. This article reviews the common infectious and noninfectious causes of fever in ICU patients and outlines a rational approach to the management of this problem.

Diagnostic testing for ventilator-associated pneumonia

This article discusses the interpretation of the diagnostic tests in the management of ventilated patients with suspicion of pneumonia. The specific steps for diagnostic evaluation are identified. An accurate interpretation of the significance of the bacterial burden requires previous evaluation of the sample quality, knowledge of administration of new antibiotics within the prior 48 hours, and evaluation of presence of comorbidities. Finally, the article presents a review of the current debate of impact on outcome.

Therapy for ventilator-associated pneumonia

Pneumonia is a serious complication of mechanical ventilation. Pneumonia occurs despite the best efforts at prevention. Multiple methods available to prevent ventilator-associated pneumonia are reviewed, and ventilation-associated pneumonia (VAP) is divided into early versus late onset. The authors discuss the organisms associated with each of these situations, the empiric antibiotic choices, and specific issues related to antibiotic therapy such as resistance, pharmcodynamics, tissue penetration, and types of modifications necessary in empiric choice when the cause of VAP is identified.

Fiberoptic bronchoscopy in coronary care unit patients: indications, safety, and clinical implications

STUDY OBJECTIVES

To evaluate the indications, safety, therapeutic impact, and outcome of fiberoptic bronchoscopy (FOB) in coronary care unit (CCU) patients.

DESIGN

Retrospective review of all CCU patients undergoing FOB during a 6-year period.

SETTING

Tertiary care university hospital.

RESULTS

Among 8,330 patients admitted to the CCU; 40 (0.5%) patients underwent FOB to evaluate pulmonary abnormalities, most often (78%) to appraise clinically suspected pneumonia. Thirty-five (88%) patients were intubated and 21 (53%) had acute myocardial infarction (MI) before FOB. There were two major complications (bleeding, intubation) occurring within 24 h of FOB, one of which appeared due to the procedure. No episodes of chest pain or ischemic events were recorded and no significant increase in major complications was noted in MI patients (3% vs 5%). Patients having FOB within 10 days of MI had higher survival (79%) than those undergoing FOB later (29%) (p = 0.05). Seven different bacterial pathogens were isolated in 6 (15%) patients, probably reflecting prior empiric antibiotics in 32 (80%) patients. Therapy was changed in 64% of patients in whom a potential pathogen was identified. Despite alterations in treatment, patients with clinically suspected pneumonia and any organisms isolated by FOB had greater mortality (79% vs 31%, p = 0.003) than those with sterile FOB cultures.

CONCLUSION

FOB may be diagnostically useful in the evaluation of pulmonary abnormalities in selected patients with acute cardiac disease, can be performed safely, and may influence management decisions. Positive bronchoscopy cultures often influence therapy but are associated with higher mortality, suggesting a lethal effect of nosocomial pneumonia in this subset of CCU patients. The risks of FOB must be weighed with the impact of FOB results on patient outcome, and its role requires further investigation.

Invasive diagnostic techniques for pneumonia: protected specimen brush, bronchoalveolar lavage, and lung biopsy methods

We suggest the following strategy for managing patients with pneumonia. For nonventilated patients with either CAP or HAP, empiric antibiotic treatment should be started according to approved guidelines, and if the clinical evolution of the patient is not adequate, fiberoptic bronchoscopy including PSB and BAL could be considered, with modification of the antibiotic treatment accordingly. In ventilated patients with either CAP or HAP, respiratory secretion sampling using noninvasive techniques should be conducted upon clinical suspicion of VAP and before starting a new antibiotic treatment. Antibiotic therapy according to approved guidelines should be started as soon as possible and maintained during the first 48 hours if the patient's evolution is satisfactory and condition has stabilized. Then, initial antibiotic treatment should be adjusted according to cultures. If there is a clear diagnostic alternative to VAP and cultures are negative, this is the only case in which antibiotic treatment could be withdrawn. If the patient's clinical evolution is inadequate (persistence of fever, leukocytosis, increasing infiltrates, and respiratory failure), fiberoptic bronchoscopy with PSB and BAL and modification of the initial antibiotic regimen should be sought. Open lung biopsy may be indicated in patients with diffuse pulmonary infiltrates in whom a diagnosis has not been achieved by other methods, including bronchoscopy. Transbronchial lung biopsy should not be viewed as a diagnostic technique for pneumonia except in immunosuppressed patients with diffuse alveolar infiltrates.

A comparison of mini-bronchoalveolar lavage and blind-protected specimen brush sampling in ventilated patients with suspected pneumonia

PURPOSE

Mini-bronchoalveolar lavage (m-BAL) and blind-protected brush sampling (b-PSB) are minimally invasive methods of diagnosing pneumonia in mechanically ventilated patients. The aim of this study was to compare these techniques in a prospective study at a medical and surgical intensive care unit in a university-affiliated community teaching hospital.

PATIENTS AND METHODS

One hundred and ninety episodes of pneumonia was suspected in 175 mechanically ventilated patients. Sequential b-PSB followed by m-BAL were performed by respiratory therapists who had undergone specialized training. A b-PSB quantitative culture greater than 1,000 cfu/mL and a m-BAL greater than 10(4) cfu/mL was considered diagnostic of pneumonia. Colony counts between 500 and 1,000 cfu/mL and 5,000 - 10(4) cfu/mL, respectively, were considered borderline positive.

RESULTS

One hundred and ninety paired specimens were obtained from 175 patients. The diagnostic agreement between the two techniques was 90%. Sixty-six patients (37%) were considered to have bacterial pneumonia. In 108 episodes, patients were receiving concurrent antibiotics; pneumonia was diagnosed in 30 (27%) of these cases compared with 36 of 82 (43%) episodes off antibiotics (P = .03). In 6 episodes, m-BAL was negative and b-PSB was positive (1 patient receiving antibiotics). In 13 episodes, b-PSB was negative and m-BAL was positive (7 patients were receiving antibiotics). The b-PSB took 30 +/- 8 seconds to perform and was complicated by minor bleeding in 3 cases. The m-BAL took 5 +/- 2 minutes to perform, was considered easy in 105 cases, difficult/very difficult in 63, and failed in 2 patients. Significant coughing occurred in 98 patients with other minor reversible complications occurring in a further 20 cases.

CONCLUSIONS

In mechanically ventilated patients with suspected pneumonia both b-PSB and m-BAL can be performed safely by respiratory therapists. The tests complement each other and likely reduce the number of false-negative results.