Reliability of the bronchoscopic protected catheter brush in intubated and ventilated patients

Flexible Fiberoptic Bronchoscopy in the Intensive Care Unit

For the past 20 years, flexible fiberoptic bronchoscopy (FOB) has been shown to be an important procedure in the diagnosis and management of patients in intensive care units (ICU). In adults, FOB is used therapeutically to remove retained secretions and to correct atelectasis not improved by conservative means. In the pediatric population, however, FOB is mainly used to diagnose tracheal disease in critically ill children. The principal risks of FOB are hypoxemia and dysrhythmias; hemor rhage and pneumothorax may occur as a result of biopsy procedures. In competent hands, these adverse compli cations of FOB are minimal. Although rigid bronchos copy remains pivotal in most pediatric bronchoscopic procedures, massive hemoptysis, foreign body removal, and laser therapy for occluding tumors of the upper airway, flexible FOB has an increasingly important role in the diagnosis and management of these disorders.

Quantitative cultures for diagnosing ventilator-associated pneumonia: a critique

The diagnosis of ventilator-associated pneumonia has been clouded by uncertainty, because a reference standard has never been established. The use of invasive procedures to obtain respiratory tract samples for culture, with quantitation of the bacteria isolated, has been the approach most commonly advocated. Quantitation of bacteria from lower respiratory tract specimens can be used to distinguish colonization from infection. We review the invasive procedures (bronchoalveolar lavage, protected specimen brushing, nonbronchoscopic bronchoalveolar lavage, and blinded bronchial sampling), the methods of quantitation used, the types of catheters used, the sample collection methods, and the criteria used as cutoffs for the quantitative cultures. Quantitation of lower respiratory tract samples is inherently unstable from a mathematical perspective, given the variability in the volume of fluid instilled and reaspirated and the magnitude and complexity of the area being sampled. We also briefly review the use of quantitation for bacterial infections other than pneumonia, including urinary tract infection and catheter-related bacteremia. The variability in both the methods and reference criteria in the studies reviewed show that the quantitation approach is neither standardized nor evidence based.

Diagnosis of ventilator-associated pneumonia: focus on nonbronchoscopic techniques (nonbronchoscopic bronchoalveolar lavage, including mini-BAL, blinded protected specimen brush, and blinded bronchial sampling) and endotracheal aspirates

The ideal diagnostic approach for ventilator-associated pneumonia currently is based on invasive procedures to obtain respiratory tract cultures. Given the lack of consensus and relatively poor acceptance of full bronchoscopic bronchoalveolar lavage (BAL) and protected specimen brush (PSB), less invasive procedures have been developed. We review the nonbronchoscopic procedures (nonbronchoscopic bronchoalveolar lavage, including mini-BAL, blinded protected specimen, and blinded bronchial sampling) and endotracheal aspiration. We provide a critique of the methods used, the types of catheters inserted, and the sample collection methods. Most studies were flawed in that antibiotic use before initiation of the procedure was not controlled. The variability of both the methods and the criteria for the gold standard in the numerous investigations show that these procedures are neither standardized nor proven to be accurate and often did not improve management. Pending future studies, use of endotracheal aspirates without the use of quantitation seems to be a reasonable approach for clinicians who are not committed to an invasive procedure.

Ventilator associated pneumonia and infection control

Ventilator associated pneumonia (VAP) is the leading cause of morbidity and mortality in intensive care units. The incidence of VAP varies from 7% to 70% in different studies and the mortality rates are 20-75% according to the study population. Aspiration of colonized pathogenic microorganisms on the oropharynx and gastrointestinal tract is the main route for the development of VAP. On the other hand, the major risk factor for VAP is intubation and the duration of mechanical ventilation. Diagnosis remains difficult, and studies showed the importance of early initiation of appropriate antibiotic for prognosis. VAP causes extra length of stay in hospital and intensive care units and increases hospital cost. Consequently, infection control policies are more rational and will save money.

Colonization of lower respiratory tract with anaerobic bacteria in mechanically ventilated patients

OBJECTIVE

To study lower respiratory tract colonization by anaerobic bacteria in ICU patients on prolonged mechanical ventilation using two types of protected tracheal sampling methods.

DESIGN AND SETTING

Prospective clinical investigation in the intensive care unit of a university hospital.

PATIENTS

Twenty-six consecutive patients mechanically ventilated within 24 h after their admission in ICU and with expected duration of mechanical ventilation longer than 7 days.

MEASUREMENTS AND RESULTS

Two types of protected tracheal sampling methods were obtained without the use of bronchoscopic guidance on the day following intubation and twice a week until extubation: protected tracheal aspiration and protected tracheal specimen brush. Specific methods for anaerobic isolation were used. Early colonization was defined if colonization occurred within the first 5 days after intubation. Of the 26 patients studied 22 were colonized by at least one bacterial strain. Twenty-one patients were colonized by aerobic and 15 by anaerobic bacteria. Twenty-eight anaerobic strains were identified, with bacterial counts higher than 10(3) cfu/ml in 11 cases. Of the 15 patients colonized by anaerobes 14 were also colonized by aerobic bacteria. The use of protected specimens ruled out oropharyngeal contamination. Early onset colonization occurred in 16 of 22 patients colonized by aerobes and in 8 of 15 patients colonized by anaerobes. Five patients developed ventilatory-acquired pneumonia following colonization (by anaerobic bacteria in two cases). In eight patients colonization by anaerobic bacteria occurred despite antimicrobial therapy.

CONCLUSIONS

These results show that anaerobic bacteria frequently colonize the lower respiratory tract of mechanically ventilated patients and underline the potential importance of the anaerobic bacteria in ventilatory acquired pneumonia.

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.

Diagnosis of nosocomial pneumonia in medical ward: repeatability of the protected specimen brush

The aims of this study were to assess the repeatability of two pairs of protected specimen brushes (PSB) done successively in the same lung area and either processed at the bedside or in the laboratory, and to provide a description of the bacteriological findings in 39 cases of suspected nosocomial pneumonia occurring in nonventilated patients. Four PSB were divided into two pairs. One pair of brushes (PB) was prepared at bedside and then sent to the laboratory; the other pair (PL) was immediately sent to the laboratory for complete processing. According to a 10(3) colony forming units (cfu) x mL(-1) threshold, 49% out of 156 PSB were positive. Using the 10(3) cfu x mL threshold, the PL brushes were 89.7% concordant while the PB brushes were 76.9% concordant. The repeatability as expressed by K-value of the cultures of PSB was higher for PL brushes than for PB brushes (K-values of 0.795 and 0.537 respectively, p=0.12). Bacterial species were isolated in 58.3% of 156 PSB (176 isolates). In 14 cases, cultures of PSB disclosed more than one micro-organism in a concentration > 10(3) cfu x mL(-1). The most frequently isolated organisms were Pseudomonas spp. (23.9%), Enterobacteriaceae (23.3%), Streptococcus spp. (21.6%) and Staphylococcus spp. (13.1%). Polymicrobial cultures were more frequent if the patient had a tracheostomy (seven out of the nine patients with a tracheostomy versus seven out of the 30 patients without a tracheostomy, p<0.01). Bacteriological discrepancies leading to a potential troublesome choice in antibiotherapy were observed in 31.8% of the patients for PL brushes and 56.5% of the patients for PB brushes. There is a low degree of repeatability of protected specimen brushes outside intensive care units which seem dependent on sampling processing. The distribution of pathogens found in case of suspicion of nosocomial pneumonia in nonventilated patients appears to be similar to that obtained in ventilator-associated pneumonia.

Are quantitative cultures useful in the diagnosis of hospital-acquired pneumonia?

Noninvasive and invasive tests have been developed and studied for their utility in diagnosing and guiding the treatment of hospital-acquired pneumonia, a condition with an inherently high mortality. Early empiric antibiotic treatment has been shown to reduce mortality, so delaying this treatment until test results are available is not justifiable. Furthermore, tailoring therapy based on results of either noninvasive or invasive tests has not been clearly shown to affect morbidity and mortality. This may be related to quantitative limitations of these tests or possibly to a high false-negative rate in patients who receive early antibiotic treatment and may therefore have suppressed bacterial counts. Results of these tests, however, do influence treatment. It is therefore hoped that they may ultimately provide a rational basis for making therapeutic decisions. In the future, outcomes research should be a part of large-scale clinical trials, and noninvasive and invasive tests should be incorporated into the design in an attempt to provide a better understanding of the value of such tests.

Protected specimen brush or bronchoalveolar lavage to diagnose bacterial nosocomial pneumonia in ventilated adults: a meta-analysis

OBJECTIVE

We conducted a meta-analysis by using summary receiver operating characteristic curves to compare the diagnostic value for bacterial nosocomial pneumonia of the following: a) quantitative culture (colony-forming units per milliliter or CFU/mL) of respiratory secretions collected with a bronchoscopic protected specimen brush (PSB); b) quantitative culture of a bronchoscopic bronchoalveolar lavage (BAL); and c) the percentage of infected cells (IC) in BAL.

DATA SOURCES

All studies published in the English or the French language, through January 1, 1995, on the evaluation of PSB or BAL for the diagnosis of pneumonia were considered for analysis. The relevant literature was identified through computer and reference searching and by experts in the field.

STUDY SELECTION

A study was included if at least two of three independent readers regarded its purpose as the evaluation of CFU-PSB, CFU-BAL, or IC-BAL for the diagnosis in human beings of bacterial nosocomial pneumonia in ventilated adults and if the study was prospective and published in a peer-reviewed journal.

DATA EXTRACTION

Three readers reviewed all published articles and decided whether to include each study; consensus was defined as agreement by at least two readers. The authors of each original article included in the meta-analysis were asked to complete a questionnaire in which they were asked to check and to correct the data extracted by one of the independent readers.

DATA SYNTHESIS

Summary receiver operating characteristic curves were used to compare the efficacy of three diagnostic tests. Eighteen studies on CFU-PSB (795 patients) were included, as well as 11 studies on CFU-BAL (435 patients) and 11 on IC-BAL (766 patients). The accuracy of these tests was not different. However, it seems that administration of previous antibiotics markedly decreased accuracy of CFU-PSB (p = .0002) but not the accuracy of CFU-BAL and that of IC-BAL.

CONCLUSION

Both PSB and BAL are reliable to diagnose bacterial nosocomial pneumonia. Because CFU-BAL and IC-BAL seemed more resistant to the effects of antibiotics, we recommend BAL rather than PSB if the patient is already receiving antibiotics.

Nosocomial pneumonia with isolation of anaerobic bacteria in ICU patients: therapeutic considerations and outcome

PURPOSE

Evaluate the influence of the anti-anaerobic antimicrobial therapy in the outcome of patients with nosocomial pneumonia.

MATERIALS AND METHODS

The population study included 53 intensive care unit patients with nosocomial pneumonia in whom, using a protected specimen brush, anaerobic bacteria were isolated, which were associated or not with aerobes. Current and empirical antibiotherapies were retrospectively analyzed, regarding their efficacy against anaerobic bacteria. Since it was debated, sensitivity to cefotaxime, ceftazidime, and ciprofloxacin was determined in 38 strains of Prevotella species. Outcome was evaluated 10 days after the day of protected specimen brushes. Improvement was defined as a decrease of Murray score or ventilator weaning.

RESULTS

The most frequently isolated bacteria were Prevotella species, which were more frequently resistant to cefotaxime (37%), ceftazidime (50%), and ciprofloxacine (32%) than usually reported in the literature. Sixty-six percent of these strains produced beta-lactamase. The effect of empirical anti-anaerobic antibiotherapy on the outcome at day 10 was evaluable in 39 patients. Twenty-nine patients were improved and 10 patients worsened. Interestingly, patients who had received well-adapted antibiotics against anaerobes had a better outcome after 10 days (P < .02).

CONCLUSIONS

This study suggests that specific antianaerobic therapy may be considered in the choice of empirical antibiotherapy in patients with nosocomial pneumonia.

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.

Ventilator-associated pneumonia

Mechanically ventilated patients are at a substantially higher risk for developing nosocomial pneumonia. Overall, there is a relatively constant 1&!TN!150;3% risk per day of developing pneumonia while receiving mechanical ventilation. The sensitivity and specificity of clinical criteria alone for diagnosis of ventilator-associated pneumonias (VAP) is low. Several techniques have been developed to sample and quantitate the lower respiratory tract to improve the diagnostic yield. Gram-negative bacillary pneumonias account for the majority of the VAP. Strategies for prevention of VAP such as use of sucralfate for stress ulcer prophylaxis and selective decontamination of the digestive tract have been the focus of many clinical studies. Cost-effective preventive measures are needed to combat the increasing antimicrobial resistance, growing population of immunocompromised patients and increasing number of mechanically ventilated patients.

Using bronchoalveolar lavage to distinguish nosocomial pneumonia from systemic inflammatory response syndrome: a prospective analysis

OBJECTIVE

Ventilator-associated pneumonia (PN) is difficult to distinguish from trauma-induced systemic inflammatory response syndrome (SIRS), especially in patients with multiple injuries. Previous work using bronchoscopy and quantitative cultures demonstrated significant bacterial growth in about one-third of patients with clinical evidence of PN. In this prospective study, antibiotic therapy for PN was based solely on quantitative bronchoalveolar lavage (BAL) cultures.

METHODS

Mechanically ventilated trauma patients underwent bronchoscopy with BAL when they developed clinical evidence of PN: fever (temperature > 100.5 degrees F), white blood cells > 10,000 or > 10% immature forms, purulent sputum, and new or changing infiltrate on chest roentgenogram. Patients with other infections or those receiving antibiotics for any other reason were excluded. Empiric antibiotic therapy for PN was started at the time of BAL. If the quantitative cultures revealed > or = 10(5) colony-forming units (CFU)/mL, that patient was defined as having PN and was treated. If the cultures revealed < 10(5) CFU/mL, that patient was defined as having SIRS, and empiric therapy was stopped.

RESULTS

Forty-three patients (88% blunt, 12% penetrating) underwent bronchoscopy with BAL 55 times. Mean age was 40 and Injury Severity Score was 25. Twenty patients had > or = 10(5) CFU/mL (47%) and 23 had < 10(5) CFU/mL (53%). There were no differences in age, Injury Severity Score, temperature, white blood cell count, or ventilator days before BAL between groups. Sixty-five percent of those with SIRS improved after empiric therapy was stopped (average 3.3 days), and 35% underwent repeat BAL. Three patients with the initial diagnosis of SIRS developed PN (13% of SIRS). Mortality for PN was 15%, compared with 17% for SIRS; no deaths were related to antibiotic therapy.

CONCLUSIONS

SIRS, which can mimic PN, is common in trauma patients. These entities can be distinguished by bronchoscopy with BAL. Basing antibiotic therapy solely on quantitative BAL cultures is efficacious in trauma patients.

The role of bronchoalveolar lavage in the diagnosis of bacterial pneumonia

Bronchoalveolar lavage (BAL) has become an invaluable diagnostic tool with important clinical implications in both opportunistic infections and the pulmonary pathology of immunologic disease. Until recently, the use of BAL was limited primarily to two areas: the study of interstitial lung diseases and the diagnosis of lung infections by opportunistic microorganisms in severely immunocompromised patients with lung infiltrates. Over the past decade, the use of BAL has been expanded to include the conventional diagnosis of bacterial pneumonia in non-immunocompromised patients. In the past, different clinical studies proposed using BAL to quantify cultures in the sample obtained as a means of increasing the tool's effectiveness. Recent developments have led to a number of newer applications of BAL, such as bronchoscopic BAL, non-bronchoscopic BAL and protected BAL. The most important use of BAL in the non-immunocompromised patient is the diagnosis of pneumonia in the mechanically ventilated patient.

Bronchoscopic diagnosis of pneumonia

Lower respiratory tract infections are characterized by significant morbidity and mortality but also by a relative inability to establish a specific etiologic agent on clinical grounds alone. With the recognized shortcomings of expectorated or aspirated secretions toward establishing an etiologic diagnosis, clinicians have increasingly used bronchoscopy to obtain diagnostic samples. A variety of specimen types may be obtained, including bronchial washes or brushes, protected specimen brushings, bronchoalveolar lavage, and transbronchial biopsies. Bronchoscopy has been applied in three primary clinical settings, including the immunocompromised host, especially human immunodeficiency virus-infected and organ transplant patients; ventilator-associated pneumonia; and severe, nonresolving community- or hospital-acquired pneumonia in nonventilated patients. In each clinical setting, and for each specimen type, specific laboratory protocols are required to provide maximal information. These protocols should provide for the use of a variety of rapid microscopic and quantitative culture techniques and the use of a variety of specific stains and selective culture to detect unusual organism groups.

New approaches in the diagnosis of nosocomial pneumonia

We have presented a review of the present literature on new modalities to diagnose nosocomial pneumonia. Procedures are now available that, when correctly used, can establish a diagnosis of pneumonia with a high degree of reliability. In our institution, reliance on bronchoscopic modalities has simplified management of patients with suspected VAP, by eliminating confusion and rationalizing antibiotic treatment. Invasive procedures, however, should be performed only if the results of cultures are consistently applied to treatment. As this field rapidly evolves, we hope that this review will provide the reader with a foundation to understand new developments.

Re-evaluation of pneumonia requiring admission to an intensive care unit: a prospective study

BACKGROUND

Appropriate treatment of severe community and hospital acquired pneumonias requiring admission to a medical intensive care unit depends on knowledge of the likely aetiological agents in any community. Little is known about the pattern and outcome of patients with such pneumonias in Saudi Arabia.

METHODS

In a prospective study 113 patients with pneumonia were investigated in the medical intensive care unit at King Khalid University Hospital, Riyadh, Saudi Arabia between September 1991 and December 1992. The diagnosis was established by microscopy and culture of sputum, blood culture, or serological examination. A standard proforma was used to collect demographic, clinical, and laboratory data.

RESULTS

A microbiological diagnosis was made in 80% of the cases with a single pathogen accounting for 69% of the isolates and multiple pathogens for 11%. Pseudomonas aeruginosa was the most common infecting agent (16%), followed by Streptococcus pneumoniae (12%), Staphylococcus aureus (9%), and Mycobacterium tuberculosis (8%). Pneumonia due to Legionella pneumophilia was diagnosed in three patients and infection due to Mycoplasma pneumoniae in two. These five cases were identified by serological examination. Gram negative rods were the predominant pathogens in both community and hospital acquired pneumonia. The aetiology of pneumonia was not identified in 20% of cases. The overall mortality was 37%. Patients with hospital acquired pneumonia had a higher mortality than those with a community acquired pneumonia. Similarly, a high mortality was found in patients who had a serious underlying disease, abnormal mental state, diastolic blood pressure < 60 mm Hg, blood urea > 7 mmol/l, abnormal liver function tests, serum albumin < 30 g/l, those who required mechanical ventilatory support, and those with APACHE II scores > 20.

CONCLUSIONS

This study highlights two major findings which differ from previous reports on the aetiology of pneumonia. Firstly, Gram negative rods were the predominant pathogens in community acquired pneumonia and secondly, M tuberculosis was an important cause of pneumonia in these patients, indicating that tuberculous pneumonia should be considered in the differential diagnosis of pneumonia in Saudi Arabia.

Diagnosis of nosocomial pneumonia in mechanically ventilated patients by the blind protected telescoping catheter

OBJECTIVES

To demonstrate that blind insertion of the protected telescoping catheter (PTC-NB) through the orotracheal tube can provide reliable pulmonary samples for the diagnosis of nosocomial pneumonia (NP) in ventilated patients.

DESIGN

We performed a random comparison between the protected telescoping catheter introduced through a bronchofiberscope (PTC-B) and the PTC-NB to diagnose NP.

SETTING

A general intensive care unit of a University Hospital.

PATIENTS

40 consecutive patients on mechanical ventilation and with suspicion of NP. The diagnosis of NP was suspected by clinical and chest X-ray findings.

MEASUREMENTS AND RESULTS

NP was confirmed microbiologically in 26 (65%) patients and maintained in 8 patients by clinical and radiological criteria. PTC-NB confirmed the microbiological diagnosis of PN in 21 (80%) patients. The use of antibiotics prior taking respiratory samples reduced the sensitivity of PTC-NB and PTC-B from 100-74% and from 94-70% (p = 0.001). Both techniques agreed in 24 of 33 (73%) patients but such agreement was better when PN was on the right lung. Two patients developed a self-limiting hemoptysis after the PTC-B procedure.

CONCLUSIONS

PTC-NB is as sensitive as specific as PTC-B for diagnosing PN in mechanically ventilated patients, being a much easier technique to use.

Fibreoptic bronchoscopy in the critically ill: a prospective study of its diagnostic and therapeutic value

AIM

A prospective study was undertaken to assess the diagnostic value and therapeutic usefulness of fibreoptic bronchoscopy in the critically ill.

METHOD

Fifty-six bronchoscopies were performed in fifty patients. Biochemical, radiological, microbiological and clinical assessments were made before and after each procedure.

RESULTS

Eighteen fibreoptic bronchoscopies were performed for therapeutic indications (32.1%) of which ten (55.6%) yielded a useful outcome. Thirty-eight bronchoscopies were for diagnostic purposes (67.8%) of which 22 (57.9%) were clinically useful. Broncho-alveolar lavage was performed in twenty-eight cases (50%) and it led to a clinically useful diagnosis in 17 (60.7%). There was no major complication. A subgroup of patients was defined (persistent left lower lobe collapse or consolidation following thoracic or abdominal surgery) in whom fibreoptic bronchoscopy usually did not yield a useful outcome.

CONCLUSION

The use of fibreoptic bronchoscopy in the Intensive Care Unit, in combination with the technique of broncho-alveolar lavage, results in a clinically useful outcome in the majority of cases. Fibreoptic bronchoscopy is an effective and safe diagnostic and therapeutic tool in critically ill patients.

Comparison of four methods for assessing airway bacteriology in intubated, mechanically ventilated patients

A prospective evaluation of lower airway bacteriology from intubated, mechanically ventilated patients was performed by comparing the qualitative and quantitative recovery of bacteria using four different techniques. Twelve intubated, mechanically ventilated patients who satisfied accepted clinical criteria for the suspicion of ventilator-associated pneumonia were studied. Airway secretions were obtained from each patient by: (1) blind endotracheal aspiration (ET); (2) Accu-cath pulmonary culture catheter (Accu); (3) bronchoscopic protected specimen brush (BPSB); and (4) bronchoalveolar lavage (BAL). ET specimens were cultured semi-quantitatively (1+ to 4+) aerobically, and all other specimens were cultured quantitatively both aerobically and anaerobically. The BPSB recovered 9 organisms in > or = 10(3) colony forming units/ml, a standard number often used to indicate significant growth. Of these 9 organisms, 7 were recovered at > or = 10(3) cfu/ml by Accu, and 6 were recovered at > or = 10(4) cfu/ml by BAL. All 8 aerobic isolates recovered in > or = 10(3) cfu/ml by BPSB also were recovered by ET aspirate. Five of these were recovered in > or = 3+ semi-quantitative growth by ET aspirate. Of 30 organisms recovered in < 3+ semi-quantitative growth by ET aspirate, 28 were recovered in < 10(3) cfu/ml by BPSB, indicating a negative predictive value of 93%. Thus, it appears that these four methods provide reasonably similar qualitative and quantitative recovery of bacteria from the lower airways of intubated, mechanically ventilated patients. In addition, routine Gram's stain and semi-quantitative aerobic culture of endotracheal aspirate may provide useful information in patients with suspected ventilator-associated pneumonia.

Management of bacterial pneumonia in ventilated patients. Protected bronchoalveolar lavage as a diagnostic tool

We conducted a prospective study to determine the effectiveness of protected bronchoalveolar lavage (PBAL) in diagnosing pneumonia in ventilated patients and the usefulness of bronchoscopic data in treating ventilated patients. Entrance criteria were (1) fever and a new or progressive infiltrate on chest roentgenogram with either leukocytosis or a macroscopically purulent tracheal aspirate, and (2) no antibiotic therapy for at least 48 h before bronchoscopy. Twenty-five ventilated patients met entrance criteria for the study and completed the protocol. PBAL was effective in retrieving distal airway secretions with a minimal degree of contamination as indicated by a specificity and a negative predictive value of 100 percent. Bacterial isolates grew in all patients with pneumonia at a concentration greater than or equal to 100,000 cfu/ml, with a median growth of 500,000 cfu/ml. The presence of a two-log difference between the highest quantitative culture count in patients without pneumonia and the lowest quantitative culture count in patients with pneumonia allowed a clearer determination of a patient's status, with regard to pneumonia, compared with the significant overlap in unprotected BAL. Gram and Giemsa stains of the PBAL were positive in all patients with pneumonia and negative in those without pneumonia. All but one patient with pneumonia received narrow-spectrum antibiotic therapy. All patients without infection had no antibiotic administered. Clinical and roentgenographic criteria could not discriminate between patients with and without pneumonia, confirming the findings of previous investigations. The results of microscopic and culture analyses of the PBAL effluent proved useful in directing antibiotic treatment in patients with pneumonia and in avoiding unnecessary antibiotic use in those patients without pneumonia.

Bronchoscopy in the intensive care unit

The development of the flexible, fiberoptic bronchoscope has made bronchoscopic examinations possible in ICU patients undergoing mechanical ventilation. Over the years, the number of such procedures has greatly increased, with both diagnostic and therapeutic objectives, such as performing difficult intubation, management of atelectasis and hemoptysis, diagnosis of nosocomial pneumonia in ventilated patients, and early detection of airway lesions in selected situations, such as high-frequency ventilation. The complication rate can be kept low if the endoscopist has a precise knowledge of the many pathophysiological and technical facets particular to bronchoscopy under these difficult conditions. This article reviews some of these aspects, in the light of our personal experience.

Etiology and diagnosis of pneumonia requiring ICU admission

The spectrum of pathogens and the microbiologic investigations used to obtain a diagnosis in 178 patients with severe pneumonia (88 percent requiring intermittent positive-pressure ventilation) are reviewed. Ninety-five patients had primary pneumonia, 31 had nosocomial pneumonia, 24 were immunocompromised patients, and 28 had aspiration pneumonia. While the spectrum of isolates conformed to the usual patterns for the different types of pneumonia, the incidence of Gram-positive infections (15 percent), predominantly Klebsiella pneumoniae, Staphylococcus aureus, (8 percent), and Legionella pneumophila (5 percent) in primary pneumonia was much higher than in community or general hospital-based studies, and only one case of Mycoplasma pneumoniae was identified. Gram stain of sputum or tracheal aspirate taken on intubation in primary pneumonia was reliably predictive of the causative organisms in both Gram-positive and Gram-negative infections when compared with infections proven by blood culture. Serologic studies were valuable in patients in whom no positive microbiologic diagnosis was evident; however, fiberoptic bronchoscopy contributed minimally to the microbiologic diagnosis in this group of patients. The cause of severe primary pneumonia differs from less severe disease, and this should be recognized when selecting empiric antibiotic therapy.

Procedures for the diagnosis of pneumonia in ICU patients

The optimal technique for diagnosing nosocomial bacterial pneumonia in critically ill patients cared for in the intensive care unit remains unclear, especially in the subgroup of patients requiring mechanical ventilation. An important advance has been the development of the protected specimen brush technique. Secretions obtained using this technique and evaluated by quantitative cultures are useful in distinguishing patients with and without pneumonia. However, this procedure has important limitations in that results are not available immediately, and in that a few false negative of false positive results may occur. Bronchoalveolar lavage has been suggested to be of value in establishing the diagnosis of pneumonia, because the cells and liquid recovered can be examined microscopically immediately after the procedure and are also suitable for quantitative culture. Microscopic identification of bacteria within cells recovered by lavage may provide a sensitive and specific means for the early and rapid diagnosis of pneumonia in this setting. The lavage technique can also be conveniently incorporated into a protocol along with quantitative culture of samples obtained using the protected specimen brush. This combination will probably improve the overall accuracy of diagnosis while allowing the administration of prompt empiric antimicrobial therapy in most patients with pneumonia.

Incidence, etiology, and outcome of nosocomial pneumonia in mechanically ventilated patients

This study assessed the incidence, etiology, and consequences of ventilator-associated pneumonia in 1,000 consecutive patients admitted in a medical-surgical intensive care unit (ICU). A total of 264 patients were submitted to mechanical ventilation (MV) for more than 48 hours. Fifty-eight (21.9 percent) patients developed a bacterial pneumonia after a mean of 7.9 days (range, 2 to 40 days) of MV. In addition, they were ten superinfections in nine patients, raising the mean incidence to 25.7 percent. Five patients developed secondary bacteremia, and another five had septic shock. Identification of the causative agent of pneumonia was possible in 47 episodes by means of highly specific techniques (telescoping plugged catheter, blood cultures, and/or necropsy). Thirteen (27.6 percent) of these cases were polymicrobial. The predominant pathogens isolated in the first episode of pneumonia were Gram-negative bacilli (62.6 percent), but a high incidence of Staphylococcus aureus infection (23.2 percent) was detected. Gram-negative bacilli represented 66.6 percent of the total organisms isolated in superinfections. The mortality rate in the pneumonia group was 42 percent; this percentage is similar to mortality rate among MV patients without pneumonia (37 percent). We conclude that nosocomial pneumonia is a frequent complication of MV in the medical-surgical ICU. Ventilator-associated pneumonia does not appear to increase fatality in critically ill patients with a high mortality rate (38 percent); however, it significantly prolongs the length of stay in the ICU for survivors.

Evaluation of the protected brush catheter and bronchoalveolar lavage in the diagnosis of nosocomial pneumonia

We assess the sensitivity and specificity of the protected brush catheter (PBC) and bronchoalveolar lavage (BAL) in diagnosing nosocomial pneumonia in nonimmunocompromised critically ill patients. Computerized bibliographic literature searches of MEDLINE were performed, and the reference list of each article selected was reviewed. Of 496 citations, there were 19 articles (describing 18 studies) that proved relevant. Study quality was assessed, and descriptive information concerning study populations, interventions, and clinically relevant outcome measurements was extracted. The sensitivity and specificity of PBC were high (pooled estimates, 89.9 and 94.5%, respectively). Criteria for a positive BAL have varied between studies, and sensitivity ranged from 53.3 to 100%, whereas specificity was 98.6%. Most studies did not report whether antibiotics were withheld on the basis of negative test results. In those that did, the incidence of adverse outcomes consequent on withholding antibiotics was low. BAL and PBC, combined with the use of quantitative cultures, appear to increase accuracy in diagnosing pneumonia. The strength of inference is hampered, however, by the absence of a "gold standard" for the diagnosis of pneumonia. Moreover, the generalizability of these findings is limited by the fact that there are so few methodologically sound studies from so few centers. A randomized trial of PBC is needed.

Diagnostic fiberoptic bronchoscopy and protected brush culture in patients with community-acquired pneumonia

A model for performing fiberoptic bronchoscopy as a supplement to noninvasive diagnostic methods, in patients with community-acquired pneumonia, was prospectively studied. Twenty-four patients underwent bronchoscopy, seven pilot patients and 17 of 277 (6 percent) consecutive patients with CAP. Indications for FOB were early therapy failure (less than or equal to 72h)(n = 7), late therapy failure (greater than 72h)(n = 11), or before start of antibiotic therapy in severely ill or immunocompromised patients (n = 6). Samples were obtained by aspiration of bronchial secretion and with a protected brush catheter from which quantitative cultures with a detection level of 10(4) colony forming units per ml were performed. Results concluded that FOB, with the use of quantitative PB-cultures, offered a safe and specific diagnostic tool, which on special indications, can be of great value in the management of patients with CAP.