Abstracts
OBJECTIVE:
To compare 28-day mortality rates and clinical outcomes in ICU patients with ventilator-associated pneumonia according to the diagnostic strategy used.
METHODS:
This was a prospective randomized clinical trial. Of the 73 patients included in the study, 36 and 37 were randomized to undergo BAL or endotracheal aspiration (EA), respectively. Antibiotic therapy was based on guidelines and was adjusted according to the results of quantitative cultures.
RESULTS:
The 28-day mortality rate was similar in the BAL and EA groups (25.0% and 37.8%, respectively; p = 0.353). There were no differences between the groups regarding the duration of mechanical ventilation, antibiotic therapy, secondary complications, VAP recurrence, or length of ICU and hospital stay. Initial antibiotic therapy was deemed appropriate in 28 (77.8%) and 30 (83.3%) of the patients in the BAL and EA groups, respectively (p = 0.551). The 28-day mortality rate was not associated with the appropriateness of initial therapy in the BAL and EA groups (appropriate therapy: 35.7% vs. 43.3%; p = 0.553; and inappropriate therapy: 62.5% vs. 50.0%; p = 1.000). Previous use of antibiotics did not affect the culture yield in the EA or BAL group (p = 0.130 and p = 0.484, respectively).
CONCLUSIONS:
In the context of this study, the management of VAP patients, based on the results of quantitative endotracheal aspirate cultures, led to similar clinical outcomes to those obtained with the results of quantitative BAL fluid cultures.
Bronchoalveolar lavage fluid/diagnosis; Respiratory aspiration; Pneumonia, ventilator-associated
OBJETIVO:
Comparar a mortalidade em 28 dias e desfechos clínicos em pacientes com pneumonia associada à ventilação mecânica (PAVM) internados em UTI conforme a estratégia diagnóstica utilizada.
MÉTODOS:
Ensaio clínico randomizado prospectivo. Dos 73 pacientes incluídos no estudo, 36 e 37, respectivamente, foram randomizados para a realização de LBA ou aspiração traqueal (AT). A antibioticoterapia inicial baseou-se em diretrizes e foi ajustada de acordo com os resultados das culturas quantitativas.
RESULTADOS:
A taxa de mortalidade em 28 dias foi semelhante nos grupos LBA e AT (25,0% e 37,8%, respectivamente; p = 0,353). Não houve diferenças entre os grupos em relação a duração da ventilação mecânica, antibioticoterapia, complicações secundárias, recidiva de PAVM ou tempo de permanência hospitalar e na UTI. A antibioticoterapia inicial foi considerada adequada em 28 (77,8%) e 30 (83,3%) dos pacientes nos grupos LBA e AT, respectivamente (p = 0,551). A mortalidade em 28 dias não se associou com a adequação da antibioticoterapia inicial nos grupos LBA e AT (tratamento apropriado: 35,7% vs. 43,3%; p = 0,553; e tratamento inapropriado: 62,5% vs. 50,0%; p = 1,000). O uso prévio de antibióticos não interferiu no rendimento das culturas nos grupos AT e LBA (p = 0,130 e p = 0,484, respectivamente).
CONCLUSÕES:
No contexto deste estudo, o manejo dos pacientes com PAVM, baseado nos resultados da cultura quantitativa do aspirado traqueal, resultou em desfechos clínicos semelhantes aos obtidos com os resultados da cultura quantitativa do LBA. (Registro Brasileiro de Ensaios Clínicos - ReBEC; número de identificação RBR-86DCDX [http://www.ensaiosclinicos.gov.br])
Lavado broncoalveolar/diagnóstico; Aspiração respiratória; Pneumonia associada à ventilação mecânica
Introduction
Ventilator-associated pneumonia (VAP) is a common complication of mechanical ventilation
(MV), with a significant mortality rate, especially when associated with potentially
antibiotic-resistant microorganisms.(
11. American Thoracic Society; Infectious Diseases Society of America.
Guidelines for the management of adults with hospital-acquired,
ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care
Med. 2005;171(4):388-416. http://dx.doi.org/10.1164/rccm.200405-644ST
http://dx.doi.org/10.1164/rccm.200405-64...
2. Melsen WG, Rovers MM, Bonten MJ. Ventilator-associated pneumonia and
mortality: a systematic review of observational studies. Crit Care Med.
2009;37(10):2709-18.http://dx.doi.org/10.1097/CCM.0b013e3181ab8655
http://dx.doi.org/10.1097/CCM.0b013e3181...
-
33. Rodrigues PM, Carmo Neto Ed, Santos LR, Knibel MF.
Ventilator-associated pneumonia: epidemiology and impact on the clinical evolution of
ICU patients. J Bras Pneumol. 2009;35(11):1084-91.
http://dx.doi.org/10.1590/S1806-37132009001100005
http://dx.doi.org/10.1590/S1806-37132009...
) Early appropriate antibiotic therapy is associated with better outcomes,
including a reduction in mortality.(
44. Alvarez-Lerma F. Modification of empiric antibiotic treatment in
patients with pneumonia acquired in the intensive care unit. ICU-Acquired Pneumonia
Study Group. Intensive Care Med. 1996;22(5):387-94.
http://dx.doi.org/10.1007/BF01712153
http://dx.doi.org/10.1007/BF01712153...
5. Luna CM, Vujacich P, Niederman MS, Vay C, Gherardi C, Matera J, et
al. Impact of BAL data on the therapy and outcome of ventilator-associated pneumonia.
Chest. 1997;111(3):678-85. http://dx.doi.org/10.1378/chest.111.3.676
http://dx.doi.org/10.1378/chest.111.3.67...
-
66. Muscedere JG, Shorr AF, Jiang X, Day A, HeylandDK; Canadian Critical
Care Trials Group.The adequacy of timely empiric antibiotic therapy for
ventilator-associated pneumonia: an important determinant of outcome. J Crit Care.
2012;27(3):322.e7-14.
)
The microbiological diagnosis of VAP can be reached by invasive methods, such as
fiberoptic bronchoscopic protected specimen brush (PSB) and BAL, or by noninvasive
methods, such as endotracheal aspiration (EA). The former methods demand expert
personnel, have potential complications, and are not promptly available; the latter
methods can be readily performed, being also cost-effective and less invasive. Ideally,
both specimens can be quantitatively cultured, aiming at reducing inappropriate
treatment and the selection of multiresistant organisms.(
77. el-Ebiary M, Torres A, González J, de la Bellacasa JP, García C,
Jiménez de Anta MT, et al. Quantitative cultures of endotracheal aspirates for the
diagnosis of ventilator-associated pneumonia. Am Rev Respir Dis. 1993;148(6 Pt
1):1552-7. http://dx.doi.org/10.1164/ajrccm/148.6_Pt_1.1552
http://dx.doi.org/10.1164/ajrccm/148.6_P...
,
88. Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani
R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial
pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40.
http://dx.doi.org/10.1164/ajrccm.152.1.7599829
http://dx.doi.org/10.1164/ajrccm.152.1.7...
) Few randomized trials examining the impact of microbiological information
on clinical outcomes related to the diagnostic strategies have shown no substantial
differences in mortality and etiologic diagnosis, although differences in the
therapeutic protocols prevent direct comparisons among them.(
99. Fagon JY, Chastre J, Wolff M, Gervais C, Parer-Aubas S, Stéphan F, et
al. Invasive and noninvasive strategies for management of suspected
ventilator-associated pneumonia. A randomized trial. Ann Intern Med.
2000;132:621-630. http://dx.doi.org/10.7326/0003-4819-132-8-200004180-00004
http://dx.doi.org/10.7326/0003-4819-132-...
10. Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, et al.
Noninvasive versus invasive microbial investigation in ventilator-associated
pneumonia: evaluation of outcome. Am J Respir Crit Care Med. 2000;162(1):119-25.
http://dx.doi.org/10.1164/ajrccm.162.1.9907090
http://dx.doi.org/10.1164/ajrccm.162.1.9...
-
1111. Sanchez-Nieto J, Torres A, Garcia-Cordoba F, El-Ebiary M, Carrillo
A, Ruiz J, et al. Impact of invasive and noninvasive quantitative culture sampling on
outcome of ventilator-associated pneumonia: a pilot study. Am J Respir Crit Care Med.
1998;157:371-6. Erratum in: Am J Respir Crit Care Med. 1998;157(3 Pt
1):1005.http://dx.doi.org/10.1164/ajrccm.157.2.97-02039
http://dx.doi.org/10.1164/ajrccm.157.2.9...
)
The objective of the present study was to compare the 28-day mortality rates in patients with microbiologically confirmed VAP. The patients were randomly assigned to two groups: LBA group, in which diagnostic work-up was carried out using BAL; and EA group, in which diagnostic work-up was carried out using EA. All of the samples of both groups were quantitatively cultured. Secondary outcomes included the length of ICU stay, adverse events due to sampling techniques, the appropriateness of antibiotic therapy and its impact on mortality, modifications in the antibiotic therapy, occurrence of secondary sepsis, occurrence of severe sepsis, occurrence of septic shock, VAP recurrence, and the need for additional diagnostic procedures.
Methods
Study population
The study population comprised consecutive adult patients (≥ 18 years of age) with a microbiologically confirmed VAP episode who had been admitted to the ICU of the institution.
The patients under MV for at least 48 h who presented with new or progressive pulmonary infiltrates on chest X-rays plus at least two of the following criteria-fever ≥ 38°C, purulent tracheal secretions, and leukocytosis ≥ 10,000 cells/mm3 or leukopenia ≤ 4,000 cells/mm3-were screened for enrollment. These patients were randomized to undergo BAL (BAL group) or EA (EA group). Both BAL fluid (BALF) and endotracheal aspirate samples were cultured. The patients whose cultures were positive-i.e., ≥ 104 CFU/mL in BALF cultures and ≥ 105 CFU/mL in quantitatively endotracheal aspirate cultures (QEACs)-were included in the study.
Patients with previously suspected nosocomial respiratory infection were enrolled only if that infection had been considered clinically and radiographically resolved. The exclusion criteria were a diagnosis of AIDS and inappropriate respiratory samples (> 10 squamous cells in the lower field magnification in endotracheal aspirate smears or > 1% bronchial cells in BALF smears). The protocol was approved by the research ethics committees of the institutions. Informed written consent was obtained from a close relative or a legal guardian of all subjects. Each patient participated only once in the study.
Study design, setting, and procedures
Between August of 2000 and January of 2003, this randomized clinical trial was conducted in a 20-bed medical and surgical ICU at a 200-bed tertiary hospital (the Hospital Madre Teresa, located in the city of Belo Horizonte, Brazil) under the auspices of the Postgraduate Program in Infectious Diseases and Tropical Medicine of the Federal University of Minas Gerais, also located in the city of Belo Horizonte.
The hypothesis was that the mortality rates and the secondary outcomes would be similar between the two study groups, regardless of the sampling method adopted.
The randomization was performed independently by one ICU administrative staff member.
Age, gender, reason for ICU admission, prior use of antibiotics, and clinical laboratory data, as well as a lung injury score, a radiological score, and the Acute Physiology and Chronic Health Evaluation II score on the day of inclusion, were also recorded. Two blood samples were drawn for bacterial cultures immediately before the retrieval of respiratory secretion specimens. The respiratory samples were quantitatively cultured for aerobic microorganisms, and diagnostic thresholds of ≥ 104 CFU/mL and ≥ 105 CFU/mL being adopted for BALF cultures and QEAC, respectively. Respiratory viruses, Legionella pneumophila, Chlamydia spp. and Mycobacterium pneumoniae were not investigated. Strains of Pseudomonas aeruginosa, Enterobacter sp., Acinetobacter sp., Stenotrophomonas maltophilia and methicillin-resistant Staphylococcus aureus (MRSA) were considered potentially resistant microorganisms. Candida sp. were considered to be colonizing microorganisms.
EA and BAL procedures
An ICU respiratory therapist performed the EA procedure. A detachable 40-cm catheter
was inserted through the endotracheal tube through a swivel adaptor without
suctioning until it had reached at least 30 cm of insertion. The specimen was drawn
with a sterile collector (Specimen Trap, St. Louis, MO, USA) and immediately sent to
the laboratory for cytological and microbiological analyses.(
88. Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani
R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial
pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40.
http://dx.doi.org/10.1164/ajrccm.152.1.7599829
http://dx.doi.org/10.1164/ajrccm.152.1.7...
)
One of the authors of the present study performed all bronchoscopies and BALF
collection procedures. After sedation, curarization, and adjustment of ventilatory
settings, BALF was collected using a fiberoptic bronchoscope without the instillation
of anesthetics or suctioning of secretions, as described in one study.(
88. Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani
R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial
pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40.
http://dx.doi.org/10.1164/ajrccm.152.1.7599829
http://dx.doi.org/10.1164/ajrccm.152.1.7...
) The bronchoscope (Olympus BF1T20D; Olympus Optical, Tokyo, Japan) was
inserted through the endotracheal tube and wedged in a subsegmental bronchus. Five
20-mL sterile saline aliquots at room temperature were infused and manually aspirated
with a 20-mL volume syringe.(
1212. Dohn MN, Baughman RP. Effect of changing instilled volume for
bronchoalveolar lavage in patients with interstitial lung disease. Am Rev Respir Dis.
1985;132(2):390-2.
) The first aliquot was discarded, and the others were pooled and
immediately sent to the laboratory. Pulse oximetry, electrocardiogram, and
ventilatory parameters were monitored throughout the procedure.
For quantitative cultures, endotracheal aspirate samples were managed using a
calibrated loop. Cytometry, cytology, and smear microscopy (May-Grünwald-Giemsa and
Gram stainings) were performed, and the proportion of cells containing intracellular
organisms (ICOs) was calculated after the counting of 300 cells at ×1000
magnification. Endotracheal aspirate samples were considered valid for culture if
< 10 squamous epithelial cells and > 25 neutrophils were present. The adopted
QEAC cut-off point for positivity was 105 CFU/mL. BALF samples were
considered appropriate for culture when < 1% of bronchial cells were found. After
cytocentrifugation, the proportion of cells containing ICOs was calculated
(May-Grünwald-Giemsa stain). BALF cultures that yielded ≥ 104 CFU/mL were
considered positive. A therapeutic protocol was employed in all of the cases, in
accordance with the American Thoracic Society guidelines (adapted to the local
epidemiology and microbial prevalence).(
11. American Thoracic Society; Infectious Diseases Society of America.
Guidelines for the management of adults with hospital-acquired,
ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care
Med. 2005;171(4):388-416. http://dx.doi.org/10.1164/rccm.200405-644ST
http://dx.doi.org/10.1164/rccm.200405-64...
)
The duration and adjustments of antibiotic therapy were based on the results of quantitative culture (BALF or endotracheal aspirate depending on the group), the clinical course, and the severity of the disease, at the discretion of the attending physician. Nonresponding patients were re-evaluated using the same initial strategy in order to establish a secondary diagnosis. Inappropriate initial antibiotic therapy was defined as the presence of bacteria resistant to or not covered by the initial antibiotic regimen. Radiological analyses were carried out independently by one of authors of the present study in accordance with a previously described methodology.(13)
Statistical analysis
Continuous data were reported as mean ± SD or median and interquartile range. Categorical data were compared using the chi-square test or Fisher's exact test. The Student's t-test or the Mann-Whitney test was used for the comparison of continuous variables. Sample size was estimated at 76 patients in order to detect a difference in the 28-day mortality rate of at least 30 percentage points between the groups studied, with a power of 0.80 and a level of significance of p < 0.05.
Results
Of the 80 screened patients, 73 were included in the study. The reasons for the exclusion of the 7 patients were as follows: negative cultures, in 2 patients; declining to participate in the study, in 2; and invalid respiratory samples, in 3 (2 endotracheal aspirate samples and 1 BALF sample). Thus, 73 patients were enrolled and randomized into the EA (n = 37) and the BAL groups (n = 36). Of the 73 patients, 47 (64.8%) were female. In the EA and BAL groups, respectively, the mean ages were 67.12 years and 64.49 years (p > 0.05; Table 1). The two groups were also similar regarding demographic data, prognostic scores, clinical data, and laboratory data. Of the 73 patients, 34 (46.6%) were on antibiotic therapy when they were included in the study (Table 1).
The mean volume of BALF collected was 34.33 ± 14.08 mL, and the mean results were 2,859.78 ± 7,635.50 cells/mL and 74.14 ± 31.3% of neutrophils. In 24 (66.7%) of the BALF samples, the mean proportion of cells containing ICOs was 3.00 ± 3.37% cells. Of the 36 BALF samples, 35 (97.2%) yielded positive quantitative cultures. On the basis of these values, the presence of cells containing ICO had a sensitivity of 0.69, a specificity of 1.0, a positive predictive value (PPV) of 1.0, and a negative predictive value (NPV) of 0.08 in relation to the presence of positive quantitative BALF cultures. The most commonly isolated bacteria in the BALF cultures were P. aeruginosa, in 9 samples (25.0%), K. pneumoniae, in 8 (22.2%); and MRSA, in 2 (5.6%). C. albicans was present in 11 cultures (30.6%).
Cells containing ICOs were found in 21 (56.8%) of the endotracheal aspirate samples, with a mean value of 4.3 ± 10.3% cells (range, 0-60%). Of the 37 QEACs, 36 (97.3%) were positive. Accordingly, the presence of ICOs showed a sensitivity of 0.59, a specificity of 0.0, a PPV of 0.98, and an NPV of 0.0 for the presence of VAP (positive QEAC being used as reference). The most commonly isolated bacteria in the endotracheal aspirate cultures were K. pneumoniae, in 12 samples (32.4%); P. aeruginosa, in 8 (21.6%), MRSA, in 5 (13.5%); S. pneumoniae, in 2 (5.4%); and others, in 27 (73.0%). C. albicans was identified in 14 samples (37.8%).
Regarding the primary outcome, the mortality rate at 28 days was 25.0% and 37.8% in the BAL and EA groups, respectively (p = 0.353; Table 2). The overall mortality and the mortality at 14 days were also similar (Table 2).
Regarding the secondary outcomes, the median duration of antibiotic therapy was 14 days in both groups. In almost 78% of the patients in the BAL group and in 83% of those in the EA group, the initial antibiotic therapy was deemed appropriate (p = 0.551), and mortality was similar in this subset of patients (35.7% vs. 43.3%, respectively; p = 0.553). When we compared the patients (of both groups) who received appropriate therapy with those who did not, mortality was also similar. The initial antibiotic regimens were modified in 87.5% and 100.0% of the patients with inappropriate antibiotic therapy in the BAL and EA groups (p = 1.0), respectively, mostly due to the microbiological results; escalation of therapy was necessary in 34.8% and in 38.1% of the patients in the BAL and EA groups, respectively, and was similar (p = 0.82). Median duration of antibiotic therapy, length of ICU stay, proportion of patients with appropriate antibiotic therapy, and mortality rates in the appropriate and inappropriate subgroup of patients, as well as the proportion and causes of modifications in the therapy, were also similar (Tables 3 and 4). Adverse events were all transient and expeditiously managed in accordance with specific recommendations. In the BAL group, no adverse events were found in 27 patients (75.0%); desaturation < 90% occurred in 2 (5.6%); transient hypotension occurred in 1 (2.8%); and sinus tachycardia > 120 bpm occurred in 7 (19.4%). In the EA group, there were no serious adverse events in 32 patients (86.5%), and all complications were transient and of no clinical significance: there were desaturation < 90% in 3 patients (8.1%), sinus tachycardia in 1 (2.7%), and bradycardia in 1 (2.7%).
Similarly, the proportions of responsive patients and of the occurrence of sepsis, severe sepsis, septic shock, secondary VAP, and noninfectious complications, as well as the need for other diagnostic procedures (data not shown) were evenly distributed in both groups (Table 5).
Discussion
The major findings of the present study were as follows: the mortality rates at 28 days after the inclusion of the patients in the study were similar, independently of the diagnostic strategy used; most patients in both groups were prescribed appropriate antibiotic therapy (78% and 83% of the patients in the BAL and EA groups, respectively), and the mortality rates were similar in these subsets of patients; other secondary outcomes were all proportionally similar, such as length of hospital and ICU stay, duration of antibiotic therapy, modification in antibiotic therapy after culture results, and use of additional diagnostic techniques, as well as the occurrence of sepsis, septic shock, secondary VAP, and organ failure.
The low accuracy of the clinical diagnosis of VAP has prompted the use of fiberoptic
bronchoscopy and quantitative cultures of respiratory samples in order to discriminate
colonization from true infection in mechanically ventilated ICU patients, which has been
supported by studies showing acceptable concordance among BALF, PSB, and postmortem
pulmonary biopsy cultures.(
88. Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani
R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial
pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40.
http://dx.doi.org/10.1164/ajrccm.152.1.7599829
http://dx.doi.org/10.1164/ajrccm.152.1.7...
,
1414. Torres A, Puig de la Bellacasa J, Xaubet A, Gonzalez J,
Rodríguez-Roisin R, Jiménez de Anta MT, et al. Diagnostic value of quantitative
cultures of bronchoalveolar lavage and telescoping plugged catheters in mechanically
ventilated patients with bacterial pneumonia. Am Rev Respir Dis.
1989;140(2):306-10.http://dx.doi.org/10.1164/ajrccm/140.2.306
http://dx.doi.org/10.1164/ajrccm/140.2.3...
15. Torres A, el-Ebiary M, Padró L, Gonzalez J, de la Bellacasa JP,
Ramirez J, et al. Validation of different techniques for the diagnosis of
ventilator-associated pneumonia. Comparison with immediate postmortem pulmonary
biopsy. Am J Respir Crit Care Med. 1994;149(2 Pt 1):324-31.
http://dx.doi.org/10.1164/ajrccm.149.2.8306025
http://dx.doi.org/10.1164/ajrccm.149.2.8...
-
1616. Marquette CH, Copin MC, Wallet F, Neviere R, Saulnier F, Mathieu D,
et al. Diagnostic tests for pneumonia in ventilated patients?: prospective evaluation
of diagnostic accuracy using histology as a diagnostic cold standard. Am J Respir
Crit Care Med. 1995;151(6):1878-88. http://dx.doi.org/10.1164/ajrccm.151.6.7767535
http://dx.doi.org/10.1164/ajrccm.151.6.7...
)
In one study, EA was considered a useful diagnostic method because of its similarity
with BAL in terms of microbial diagnosis and clinical outcomes, especially when
endotracheal aspirate samples are quantitatively cultured.(
1717. Carvalho MV, Winkeler GF, Costa FAM, Bandeira TJ, Pereira ED,
Holanda MA. Concordance between tracheal aspirate and bronchoalveolar lavage in the
diagnosis of ventilator associated pneumonia. J Bras Pneumol.
2004;30(1):26-38.
) However, robust evidence favoring one of these methods in the management of
VAP patients is still lacking. (
99. Fagon JY, Chastre J, Wolff M, Gervais C, Parer-Aubas S, Stéphan F, et
al. Invasive and noninvasive strategies for management of suspected
ventilator-associated pneumonia. A randomized trial. Ann Intern Med.
2000;132:621-630. http://dx.doi.org/10.7326/0003-4819-132-8-200004180-00004
http://dx.doi.org/10.7326/0003-4819-132-...
10. Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, et al.
Noninvasive versus invasive microbial investigation in ventilator-associated
pneumonia: evaluation of outcome. Am J Respir Crit Care Med. 2000;162(1):119-25.
http://dx.doi.org/10.1164/ajrccm.162.1.9907090
http://dx.doi.org/10.1164/ajrccm.162.1.9...
-
1111. Sanchez-Nieto J, Torres A, Garcia-Cordoba F, El-Ebiary M, Carrillo
A, Ruiz J, et al. Impact of invasive and noninvasive quantitative culture sampling on
outcome of ventilator-associated pneumonia: a pilot study. Am J Respir Crit Care Med.
1998;157:371-6. Erratum in: Am J Respir Crit Care Med. 1998;157(3 Pt
1):1005.http://dx.doi.org/10.1164/ajrccm.157.2.97-02039
http://dx.doi.org/10.1164/ajrccm.157.2.9...
,
1818. Niederman MS, Soulountsi V. De-escalation therapy: is it valuable
for the management of ventilator-associated pneumonia? Clin Chest Med.
2011;32(3):517-34.http://dx.doi.org/10.1016/j.ccm.2011.05.009
http://dx.doi.org/10.1016/j.ccm.2011.05....
19. Rouby JJ, Martin De Lassale E, Poete P, Nicolas MH, Bodin L, Jarlier
V, et al. Nosocomial bronchopneumonia in the critically ill. Histologic and
bacteriologic aspects. Am Rev Respir Dis. 1992;146(4):1059-66.
http://dx.doi.org/10.1164/ajrccm/146.4.1059
http://dx.doi.org/10.1164/ajrccm/146.4.1...
-
2020. Mentec H, May-Michelangeli L, Rabbat A, Varon E, Le Turdu F,
Bleichner G. Blind and bronchoscopic sampling methods in suspected
ventilator-associated pneumonia. A multicentre prospective study. Intensive Care Med.
2004;30(7):1319-26. http://dx.doi.org/10.1007/s00134-004-2284-7
http://dx.doi.org/10.1007/s00134-004-228...
) The adoption of invasive or noninvasive strategies has not resulted in
clear differences in terms of outcomes when quantitative cultures are
performed.(9-11,21,22) One group of authors reported that patients with
suspected VAP who had been managed by means of BAL showed lower 14-day mortality rate,
earlier resolution, earlier attenuation of organ failure, and less antibiotic use than
did controls managed by means of QEAC; however, those differences could have been
influenced by the use of qualitative cultures in the endotracheal aspirate arm of the
study, which prevented any adjustments to the therapy.(
99. Fagon JY, Chastre J, Wolff M, Gervais C, Parer-Aubas S, Stéphan F, et
al. Invasive and noninvasive strategies for management of suspected
ventilator-associated pneumonia. A randomized trial. Ann Intern Med.
2000;132:621-630. http://dx.doi.org/10.7326/0003-4819-132-8-200004180-00004
http://dx.doi.org/10.7326/0003-4819-132-...
) In two studies,(
1010. Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, et al.
Noninvasive versus invasive microbial investigation in ventilator-associated
pneumonia: evaluation of outcome. Am J Respir Crit Care Med. 2000;162(1):119-25.
http://dx.doi.org/10.1164/ajrccm.162.1.9907090
http://dx.doi.org/10.1164/ajrccm.162.1.9...
,
1111. Sanchez-Nieto J, Torres A, Garcia-Cordoba F, El-Ebiary M, Carrillo
A, Ruiz J, et al. Impact of invasive and noninvasive quantitative culture sampling on
outcome of ventilator-associated pneumonia: a pilot study. Am J Respir Crit Care Med.
1998;157:371-6. Erratum in: Am J Respir Crit Care Med. 1998;157(3 Pt
1):1005.http://dx.doi.org/10.1164/ajrccm.157.2.97-02039
http://dx.doi.org/10.1164/ajrccm.157.2.9...
) similar clinical outcomes were found concerning the use of quantitative
BAL, PSB, and EA techniques, except for a higher frequency of therapeutic modifications
in the quantitative BAL and PSB groups. No significant differences were found in terms
of mortality rates. One group of investigators also found that quantitative BALF
cultures and nonquantitative endotracheal aspirate cultures were associated with similar
clinical outcomes and use of antibiotics; however, some drawbacks of their research were
the exclusion of patients with MRSA or Pseudomonas sp., the
nonquantitative culture methodology used in the endotracheal aspirate samples, and the
use of broad-spectrum antibiotics in both groups, which could have limited the strength
of their results. (
2323. Canadian Critical Care Trials Group. A randomized trial of
diagnostic techniques for ventilator-associated pneumonia. N Engl J Med.
2006;355(25):2619-30.http://dx.doi.org/10.1056/NEJMoa052904
http://dx.doi.org/10.1056/NEJMoa052904...
) In addition, a meta-analysis demonstrated no evidence that the use of
invasive strategies could result in reduced mortality, shorter length of ICU stay,
shorter duration of MV, or higher rates of antibiotic regimen changes when compared with
the use of noninvasive strategies.(
2424. Berton DC, Kalil AC, Teixeira PJ. Quantitative versus qualitative
cultures of respiratory secretions for clinical outcomes in patients with ventilator-
associated pneumonia. Cochrane Database Syst Rev. 2008; 1:CD006482.
)
In spite of the limitations of the use of mortality rates as the endpoint in studies
involving ICU patients,(
22. Melsen WG, Rovers MM, Bonten MJ. Ventilator-associated pneumonia and
mortality: a systematic review of observational studies. Crit Care Med.
2009;37(10):2709-18.http://dx.doi.org/10.1097/CCM.0b013e3181ab8655
http://dx.doi.org/10.1097/CCM.0b013e3181...
,
2525. Muscedere J, Dodek P, Keenan S, Fowler R, Cook D, Heyland D, et al.
Comprehensive evidence-based clinical practice guidelines for ventilator-associated
pneumonia: prevention. J Crit Care. 2008;23(1):126-37.
http://dx.doi.org/10.1016/j.jcrc.2007.11.014
http://dx.doi.org/10.1016/j.jcrc.2007.11...
,
2626. Bekaert M, Timsit JF, Vansteelandt S, Depuydt P, Vésin A,
Garrouste-Orgeas M, et al. Attributable mortality of ventilator-associated pneumonia:
a reappraisal using causal analysis. Am J Respir Crit Care Med. 2011;184(10):1133-9.
http://dx.doi.org/10.1164/rccm.201105-0867OC
http://dx.doi.org/10.1164/rccm.201105-08...
) the present study reinforces the concept that the mortality rate involves
multifactorial variables, and it appears to be independent of diagnostic techniques used
for collection of respiratory samples in VAP patients as long as a comprehensive
protocol is appropriately followed.(
77. el-Ebiary M, Torres A, González J, de la Bellacasa JP, García C,
Jiménez de Anta MT, et al. Quantitative cultures of endotracheal aspirates for the
diagnosis of ventilator-associated pneumonia. Am Rev Respir Dis. 1993;148(6 Pt
1):1552-7. http://dx.doi.org/10.1164/ajrccm/148.6_Pt_1.1552
http://dx.doi.org/10.1164/ajrccm/148.6_P...
,
1010. Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, et al.
Noninvasive versus invasive microbial investigation in ventilator-associated
pneumonia: evaluation of outcome. Am J Respir Crit Care Med. 2000;162(1):119-25.
http://dx.doi.org/10.1164/ajrccm.162.1.9907090
http://dx.doi.org/10.1164/ajrccm.162.1.9...
,
1717. Carvalho MV, Winkeler GF, Costa FAM, Bandeira TJ, Pereira ED,
Holanda MA. Concordance between tracheal aspirate and bronchoalveolar lavage in the
diagnosis of ventilator associated pneumonia. J Bras Pneumol.
2004;30(1):26-38.
)
One important cofactor is the previous use of antibiotics, a usual context at the time
of suspicion of VAP. It has been accepted that this might impair the yield of cultures
and is associated with higher VAP mortality and selection of potentially resistant
bacteria.(
1313. Fagon JY, Chastre J, Hance AJ, Montravers P, Novara A, Gibert C.
Nosocomial pneumonia in ventilated patients: a cohort study evaluating attributable
mortality and hospital stay. Am J Med. 1993;94(3):281-8.
http://dx.doi.org/10.1016/0002-9343(93)90060-3
http://dx.doi.org/10.1016/0002-9343(93)9...
,
1515. Torres A, el-Ebiary M, Padró L, Gonzalez J, de la Bellacasa JP,
Ramirez J, et al. Validation of different techniques for the diagnosis of
ventilator-associated pneumonia. Comparison with immediate postmortem pulmonary
biopsy. Am J Respir Crit Care Med. 1994;149(2 Pt 1):324-31.
http://dx.doi.org/10.1164/ajrccm.149.2.8306025
http://dx.doi.org/10.1164/ajrccm.149.2.8...
,
2727. Kollef MH, Sherman G, Ward S, Fraser VJ. Inadequate antimicrobial
treatment of infections: a risk factor for hospital mortality among critically ill
patients. Chest. 1999;115(2):462-74. http://dx.doi.org/10.1378/chest.115.2.462
http://dx.doi.org/10.1378/chest.115.2.46...
28. Timsit JF, Misset B, Renaud B, Goldstein FW, Carlet J. Effect of
previous antimicrobial therapy on the accuracy of the main procedures used to
diagnose nosocomial pneumonia in patients who are using ventilation. Chest.
1995;108(4):1036-40. http://dx.doi.org/10.1378/chest.108.4.1036
http://dx.doi.org/10.1378/chest.108.4.10...
29. Trouillet JL, Chastre J, Vuagnat A, Joly-Guillou ML, Combaux D,
Dombret MC, et al. Ventilator-associated pneumonia caused by potentially
drug-resistant bacteria. Am J Respir Crit Care Med. 1998;157(2):531-9.
http://dx.doi.org/10.1164/ajrccm.157.2.9705064
http://dx.doi.org/10.1164/ajrccm.157.2.9...
-
3030. Wu CL, Yang DIe, Wang NY, Kuo HT, Chen PZ. Quantitative culture of
endotracheal aspirates in the diagnosis of ventilator-associated pneumonia in
patients with treatment failure. Chest. 2002;122(2):662-8.
http://dx.doi.org/10.1378/chest.122.2.662
http://dx.doi.org/10.1378/chest.122.2.66...
) In our series, almost half of our patients were on antibiotic therapy at
the time of enrollment (44.0% and 48.6% in the BAL and EA groups, respectively).
Similarly, it was associated with the isolation of resistant microorganisms. However, a
negative impact of this variable on the yield of cultures was not found, which is in
agreement with the available literature. This finding could be explained by the overall
median of 6 days of previous antibiotic use, which is longer than the limit of 3 days
reported in the literature as the point of no interference with culture
yield.(
2828. Timsit JF, Misset B, Renaud B, Goldstein FW, Carlet J. Effect of
previous antimicrobial therapy on the accuracy of the main procedures used to
diagnose nosocomial pneumonia in patients who are using ventilation. Chest.
1995;108(4):1036-40. http://dx.doi.org/10.1378/chest.108.4.1036
http://dx.doi.org/10.1378/chest.108.4.10...
,
3131. Souweine B, Veber B, Bedos JP, Gachot B, Dombret MC, Regnier B, et
al. Diagnostic accuracy of protected specimen brush and bronchoalveolar lavage in
nosocomial pneumonia: impact of previous antimicrobial treatments. Crit Care Med.
1998;26(2):236-44. http://dx.doi.org/10.1097/00003246-199802000-00017
http://dx.doi.org/10.1097/00003246-19980...
)
Although adjustments in the antibiotic regimens were similarly carried out in both groups, they had no impact on mortality rates, length of ICU stay, length of hospital stay, duration of antibiotic therapy, duration of MV, or rate of complications, regardless of the procedure adopted.
Our findings refer to a single ICU, which might not reflect other critical health care
contexts. Because VAP still lacks a gold standard method of diagnosis, the therapeutic
modifications were not exclusively based on the microbiological results. In addition, as
it has been reported on in other studies,(
88. Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani
R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial
pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40.
http://dx.doi.org/10.1164/ajrccm.152.1.7599829
http://dx.doi.org/10.1164/ajrccm.152.1.7...
,
1515. Torres A, el-Ebiary M, Padró L, Gonzalez J, de la Bellacasa JP,
Ramirez J, et al. Validation of different techniques for the diagnosis of
ventilator-associated pneumonia. Comparison with immediate postmortem pulmonary
biopsy. Am J Respir Crit Care Med. 1994;149(2 Pt 1):324-31.
http://dx.doi.org/10.1164/ajrccm.149.2.8306025
http://dx.doi.org/10.1164/ajrccm.149.2.8...
) we might have included false positive and false negative cases.
Nevertheless, the microbial identification might locally contribute to the optimal
management of VAP patients by recognizing the local flora and further enhancing the
rates of appropriate therapy.
In conclusion, we found no differences in the 28-day mortality rates or other clinical outcomes that could be linked to the diagnostic methods used in this study for the confirmation of VAP. Therefore, QEAC can be considered a practicable tool in the microbiological diagnosis of VAP. The prior use of antibiotics, in similar contexts, might not interfere with the yield of respiratory cultures.
References
-
1American Thoracic Society; Infectious Diseases Society of America. Guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia. Am J Respir Crit Care Med. 2005;171(4):388-416. http://dx.doi.org/10.1164/rccm.200405-644ST
» http://dx.doi.org/10.1164/rccm.200405-644ST -
2Melsen WG, Rovers MM, Bonten MJ. Ventilator-associated pneumonia and mortality: a systematic review of observational studies. Crit Care Med. 2009;37(10):2709-18.http://dx.doi.org/10.1097/CCM.0b013e3181ab8655
» http://dx.doi.org/10.1097/CCM.0b013e3181ab8655 -
3Rodrigues PM, Carmo Neto Ed, Santos LR, Knibel MF. Ventilator-associated pneumonia: epidemiology and impact on the clinical evolution of ICU patients. J Bras Pneumol. 2009;35(11):1084-91. http://dx.doi.org/10.1590/S1806-37132009001100005
» http://dx.doi.org/10.1590/S1806-37132009001100005 -
4Alvarez-Lerma F. Modification of empiric antibiotic treatment in patients with pneumonia acquired in the intensive care unit. ICU-Acquired Pneumonia Study Group. Intensive Care Med. 1996;22(5):387-94. http://dx.doi.org/10.1007/BF01712153
» http://dx.doi.org/10.1007/BF01712153 -
5Luna CM, Vujacich P, Niederman MS, Vay C, Gherardi C, Matera J, et al. Impact of BAL data on the therapy and outcome of ventilator-associated pneumonia. Chest. 1997;111(3):678-85. http://dx.doi.org/10.1378/chest.111.3.676
» http://dx.doi.org/10.1378/chest.111.3.676 -
6Muscedere JG, Shorr AF, Jiang X, Day A, HeylandDK; Canadian Critical Care Trials Group.The adequacy of timely empiric antibiotic therapy for ventilator-associated pneumonia: an important determinant of outcome. J Crit Care. 2012;27(3):322.e7-14.
-
7el-Ebiary M, Torres A, González J, de la Bellacasa JP, García C, Jiménez de Anta MT, et al. Quantitative cultures of endotracheal aspirates for the diagnosis of ventilator-associated pneumonia. Am Rev Respir Dis. 1993;148(6 Pt 1):1552-7. http://dx.doi.org/10.1164/ajrccm/148.6_Pt_1.1552
» http://dx.doi.org/10.1164/ajrccm/148.6_Pt_1.1552 -
8Chastre J, Fagon JY, Bornet-Lecso M, Calvat S, Dombret MC, al Khani R, et al. Evaluation of bronchoscopic techniques for the diagnosis of nosocomial pneumonia. Am J Respir Crit Care Med. 1995;152(1):231-40. http://dx.doi.org/10.1164/ajrccm.152.1.7599829
» http://dx.doi.org/10.1164/ajrccm.152.1.7599829 -
9Fagon JY, Chastre J, Wolff M, Gervais C, Parer-Aubas S, Stéphan F, et al. Invasive and noninvasive strategies for management of suspected ventilator-associated pneumonia. A randomized trial. Ann Intern Med. 2000;132:621-630. http://dx.doi.org/10.7326/0003-4819-132-8-200004180-00004
» http://dx.doi.org/10.7326/0003-4819-132-8-200004180-00004 -
10Ruiz M, Torres A, Ewig S, Marcos MA, Alcón A, Lledó R, et al. Noninvasive versus invasive microbial investigation in ventilator-associated pneumonia: evaluation of outcome. Am J Respir Crit Care Med. 2000;162(1):119-25. http://dx.doi.org/10.1164/ajrccm.162.1.9907090
» http://dx.doi.org/10.1164/ajrccm.162.1.9907090 -
11Sanchez-Nieto J, Torres A, Garcia-Cordoba F, El-Ebiary M, Carrillo A, Ruiz J, et al. Impact of invasive and noninvasive quantitative culture sampling on outcome of ventilator-associated pneumonia: a pilot study. Am J Respir Crit Care Med. 1998;157:371-6. Erratum in: Am J Respir Crit Care Med. 1998;157(3 Pt 1):1005.http://dx.doi.org/10.1164/ajrccm.157.2.97-02039
» http://dx.doi.org/10.1164/ajrccm.157.2.97-02039 -
12Dohn MN, Baughman RP. Effect of changing instilled volume for bronchoalveolar lavage in patients with interstitial lung disease. Am Rev Respir Dis. 1985;132(2):390-2.
-
13Fagon JY, Chastre J, Hance AJ, Montravers P, Novara A, Gibert C. Nosocomial pneumonia in ventilated patients: a cohort study evaluating attributable mortality and hospital stay. Am J Med. 1993;94(3):281-8. http://dx.doi.org/10.1016/0002-9343(93)90060-3
» http://dx.doi.org/10.1016/0002-9343(93)90060-3 -
14Torres A, Puig de la Bellacasa J, Xaubet A, Gonzalez J, Rodríguez-Roisin R, Jiménez de Anta MT, et al. Diagnostic value of quantitative cultures of bronchoalveolar lavage and telescoping plugged catheters in mechanically ventilated patients with bacterial pneumonia. Am Rev Respir Dis. 1989;140(2):306-10.http://dx.doi.org/10.1164/ajrccm/140.2.306
» http://dx.doi.org/10.1164/ajrccm/140.2.306 -
15Torres A, el-Ebiary M, Padró L, Gonzalez J, de la Bellacasa JP, Ramirez J, et al. Validation of different techniques for the diagnosis of ventilator-associated pneumonia. Comparison with immediate postmortem pulmonary biopsy. Am J Respir Crit Care Med. 1994;149(2 Pt 1):324-31. http://dx.doi.org/10.1164/ajrccm.149.2.8306025
» http://dx.doi.org/10.1164/ajrccm.149.2.8306025 -
16Marquette CH, Copin MC, Wallet F, Neviere R, Saulnier F, Mathieu D, et al. Diagnostic tests for pneumonia in ventilated patients?: prospective evaluation of diagnostic accuracy using histology as a diagnostic cold standard. Am J Respir Crit Care Med. 1995;151(6):1878-88. http://dx.doi.org/10.1164/ajrccm.151.6.7767535
» http://dx.doi.org/10.1164/ajrccm.151.6.7767535 -
17Carvalho MV, Winkeler GF, Costa FAM, Bandeira TJ, Pereira ED, Holanda MA. Concordance between tracheal aspirate and bronchoalveolar lavage in the diagnosis of ventilator associated pneumonia. J Bras Pneumol. 2004;30(1):26-38.
-
18Niederman MS, Soulountsi V. De-escalation therapy: is it valuable for the management of ventilator-associated pneumonia? Clin Chest Med. 2011;32(3):517-34.http://dx.doi.org/10.1016/j.ccm.2011.05.009
» http://dx.doi.org/10.1016/j.ccm.2011.05.009 -
19Rouby JJ, Martin De Lassale E, Poete P, Nicolas MH, Bodin L, Jarlier V, et al. Nosocomial bronchopneumonia in the critically ill. Histologic and bacteriologic aspects. Am Rev Respir Dis. 1992;146(4):1059-66. http://dx.doi.org/10.1164/ajrccm/146.4.1059
» http://dx.doi.org/10.1164/ajrccm/146.4.1059 -
20Mentec H, May-Michelangeli L, Rabbat A, Varon E, Le Turdu F, Bleichner G. Blind and bronchoscopic sampling methods in suspected ventilator-associated pneumonia. A multicentre prospective study. Intensive Care Med. 2004;30(7):1319-26. http://dx.doi.org/10.1007/s00134-004-2284-7
» http://dx.doi.org/10.1007/s00134-004-2284-7 -
21Kollef MH, Ward S. The influence of mini-BAL cultures on patient outcomes: implications for the antibiotic management of ventilator-associated pneumonia. Chest. 1998;113(2):412-20. http://dx.doi.org/10.1378/chest.113.2.412
» http://dx.doi.org/10.1378/chest.113.2.412 -
22Solé Violán J, Fernández JA, Benítez AB, Carde-osa Cendrero JA, Rodríguez de Castro F. Impact of quantitative invasive diagnostic techniques in the management and outcome of mechanically ventilated patients with suspected pneumonia. Crit Care Med. 2000;28(8):2737-41. http://dx.doi.org/10.1097/00003246-200008000-00009
» http://dx.doi.org/10.1097/00003246-200008000-00009 -
23Canadian Critical Care Trials Group. A randomized trial of diagnostic techniques for ventilator-associated pneumonia. N Engl J Med. 2006;355(25):2619-30.http://dx.doi.org/10.1056/NEJMoa052904
» http://dx.doi.org/10.1056/NEJMoa052904 -
24Berton DC, Kalil AC, Teixeira PJ. Quantitative versus qualitative cultures of respiratory secretions for clinical outcomes in patients with ventilator- associated pneumonia. Cochrane Database Syst Rev. 2008; 1:CD006482.
-
25Muscedere J, Dodek P, Keenan S, Fowler R, Cook D, Heyland D, et al. Comprehensive evidence-based clinical practice guidelines for ventilator-associated pneumonia: prevention. J Crit Care. 2008;23(1):126-37. http://dx.doi.org/10.1016/j.jcrc.2007.11.014
» http://dx.doi.org/10.1016/j.jcrc.2007.11.014 -
26Bekaert M, Timsit JF, Vansteelandt S, Depuydt P, Vésin A, Garrouste-Orgeas M, et al. Attributable mortality of ventilator-associated pneumonia: a reappraisal using causal analysis. Am J Respir Crit Care Med. 2011;184(10):1133-9. http://dx.doi.org/10.1164/rccm.201105-0867OC
» http://dx.doi.org/10.1164/rccm.201105-0867OC -
27Kollef MH, Sherman G, Ward S, Fraser VJ. Inadequate antimicrobial treatment of infections: a risk factor for hospital mortality among critically ill patients. Chest. 1999;115(2):462-74. http://dx.doi.org/10.1378/chest.115.2.462
» http://dx.doi.org/10.1378/chest.115.2.462 -
28Timsit JF, Misset B, Renaud B, Goldstein FW, Carlet J. Effect of previous antimicrobial therapy on the accuracy of the main procedures used to diagnose nosocomial pneumonia in patients who are using ventilation. Chest. 1995;108(4):1036-40. http://dx.doi.org/10.1378/chest.108.4.1036
» http://dx.doi.org/10.1378/chest.108.4.1036 -
29Trouillet JL, Chastre J, Vuagnat A, Joly-Guillou ML, Combaux D, Dombret MC, et al. Ventilator-associated pneumonia caused by potentially drug-resistant bacteria. Am J Respir Crit Care Med. 1998;157(2):531-9. http://dx.doi.org/10.1164/ajrccm.157.2.9705064
» http://dx.doi.org/10.1164/ajrccm.157.2.9705064 -
30Wu CL, Yang DIe, Wang NY, Kuo HT, Chen PZ. Quantitative culture of endotracheal aspirates in the diagnosis of ventilator-associated pneumonia in patients with treatment failure. Chest. 2002;122(2):662-8. http://dx.doi.org/10.1378/chest.122.2.662
» http://dx.doi.org/10.1378/chest.122.2.662 -
31Souweine B, Veber B, Bedos JP, Gachot B, Dombret MC, Regnier B, et al. Diagnostic accuracy of protected specimen brush and bronchoalveolar lavage in nosocomial pneumonia: impact of previous antimicrobial treatments. Crit Care Med. 1998;26(2):236-44. http://dx.doi.org/10.1097/00003246-199802000-00017
» http://dx.doi.org/10.1097/00003246-199802000-00017
-
Financial support: Manoel Otávio da Costa Rocha is a recipient of a Research Productivity Scholarship (Level 1B) from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, National Council for Scientific and Technological Development)
-
*
Study carried out under the auspices of the Postgraduate Program in Health Sciences, Infectology and Tropical Medicine, Federal University of Minas Gerais School of Medicine, Belo Horizonte, Brazil
-
**
A versão completa em português deste artigo está disponível em www.jornaldepneumologia.com.br
Publication Dates
-
Publication in this collection
Nov-Dec 2014
History
-
Received
02 Dec 2013 -
Accepted
12 May 2014