Diagnosis of Ventilator- Associated Pneumonia in Children: A Comparative Study of Bronchoscopic and Non-Bronchoscopic Methods
Condition: Ventilator Associated Pneumonia
MeSH terms: Pneumonia; Pneumonia, Ventilator-Associated
Study type: Interventional
Phase: Phase 3

Summary: 
      Background and Objectives: There is a need to validate and suggest easy and less costly
      diagnostic method for diagnosis of ventilator-associated pneumonia in developing country. The
      study was performed to compare available methods for the diagnosis and to characterize the
      organisms causing VAP.

      Design and Methods: All patients on mechanical ventilation for more than 48 hours and
      simplified CPIS ≥ 6 were enrolled prospectively. Four diagnostic procedures, endotracheal
      aspiration (ETA), blind bronchial sampling (BBS), blind bronchoalveolar lavage (blind BAL)
      and bronchoscopic BAL (BAL) were performed in same sequence within 12 hours. The bacterial
      density ≥ 104 cfu/ mL BAL samples were taken as reference standard.
    

Detailed description: 
      Introduction Ventilator associated pneumonia (VAP) is defined as nosocomial pneumonia
      developing in a patient 48 hours after the initiation of mechanical ventilatory support (by
      endotracheal tube (ETT) or tracheostomy tube) (1). Despite major advances in the techniques
      for the management of ventilator dependent patients, VAP continues to complicate the course
      of 8-28% of the patients receiving mechanical ventilation (MV) (1-3). Rates of pneumonia are
      considerably higher among patients hospitalized in intensive care units (ICUs) compared with
      those in the hospital wards. The risk of pneumonia is increased 3 to 10 folds for the
      intubated patient receiving mechanical ventilation (1, 2, 4-6). The mortality with VAP is
      considerably high, varying from 24 to 50% and can reach as high as 76% in some specific
      settings or when lung infection is caused by high risk pathogens (1).

      For many years, VAP was diagnosed by clinical criteria such as fever, leukocytosis and
      purulent tracheobronchial secretions supported by the radiological evidence of new or
      persistent pulmonary infiltrates (7). However these criteria are non-specific (8). Studies
      have shown that clinical criteria have imperfect diagnostic reliability in ventilated
      patients, and therefore, additional procedures such as cultures of the lower respiratory
      tract are required for the accurate diagnosis and treatment of VAP (9, 10). However, clinical
      criteria do remain crucial for defining those patients who may require respiratory sampling
      (1).

      Given the invasive nature and high incidence of complications with techniques such as lung
      biopsy and percutaneous needle aspiration, these have now been replaced by safer methods such
      as endotracheal aspiration (ETA), bronchoscopic bronchoalveolar lavage (BAL), protected
      sampling brushing (PSB) and non-bronchoscopic methods such as blind BAL and blind bronchial
      aspirates (BBA) as approaches for the definitive diagnosis of VAP (8, 12). The ETA is the
      most widely used sampling technique in ventilated patients (13). This technique is known to
      have a high sensitivity but also has a high false positive rate and correlates poorly to
      actual pathogen due to respiratory tract colonization (14). Invasive bronchoscopic sampling
      techniques like bronchoscopic BAL and PSB are currently considered as the reliable sampling
      techniques in adult ICU to recover organism from the lower respiratory tract (15) and have
      high sensitivity and specificity (16). The usefulness of these techniques in routine clinical
      practice is, however, hampered by the potential risks of bronchoscopy, the unavailability of
      equipment and trained personnel on a 24-hour basis in many critical care facilities and the
      associated cost.

      The microscopic identification of organisms causing pneumonia requires a simple, safe,
      effective and inexpensive method with good sensitivity and specificity with results at least
      equal to bronchoscopic BAL. Non-bronchoscopic bronchoalveolar lavage and BBS have been
      reported to have good efficacy in the microbiological diagnosis of VAP (17- 19). Though these
      techniques have not been standardized in children, they appear promising (20).

      The methods of diagnosing VAP are debatable and there is no accepted 'gold standard'. No
      study has shown the superiority of a specific method. The methods proposed have different
      sensitivities and specificities (11). So, additional validation studies are needed. Other
      indications of the need for further studies of the non-bronchoscopically directed techniques
      are the absence of standardized diagnostic thresholds for quantitative cultures, and to
      develop cheaper, reliable and easy to use diagnostic method involving inexpensive easily
      available equipment.

      Numerous studies have been conducted in the adult medical and surgical ICUs (1, 5, 12, 13,
      16-18) establishing the above-mentioned techniques as reliable methods for the diagnosis of
      VAP, but corresponding studies in children are very few (21, 22) and none from the developing
      world.

      Therefore this prospective study was conducted to know the causative microorganisms and to
      evaluate and compare the four procedures namely endotracheal aspirates (ETA), blind bronchial
      sampling (BBS),blind bronchoalveolar lavage (blind BAL), and bronchoscopic bronchoalveolar
      lavage (BAL) for the diagnosis of VAP in the tertiary care PICU of a developing country.

      Materials and Methods

      Hospital, ICU characteristics and Facilities. This prospective study was conducted in the
      6-bedded PICU of a tertiary care multidisciplinary teaching hospital. This 600-bedded
      hospital has separate adult medical and surgical, pediatric, neonatal, cardiac and post
      transplant ICUs.The PICU is equipped with 6 ventilators, central oxygen, air and vacuum
      supply. Each bed has multiparameter monitor for continuous hemodynamic and respiratory
      monitoring .Nurse on duty maintain vital sign and intake-output record on hourly basis.
      Besides standard treatment modalities and ventilation, bedside renal replacement therapy,
      electroencephalography, echocardiography and flexible bronchoscopy facilities are available.
      Extracorporeal membrane oxygenation and nitric oxide therapies are not yet available. The
      PICU is staffed with full time, experienced pediatric intensivists, critical care fellows and
      residents. The nurse / patient ratio of 1:2 is provided round the clock.

      Study Population and data collection. During 9 months period (January to September 2003) of
      study all patients on mechanical ventilation for more than 48 hours by endotracheal tube or
      tracheostomy were evaluated for the development of VAP. Data pertaining to the clinical
      suspicion of pneumonia included daily temperature, total leucocytes counts, PaO2 / FiO2
      ratio, nature of tracheobronchial secretions, and chest X-ray. Each patient was assigned a
      score based on the simplified clinical pulmonary infection score (CPIS) criteria (23). Total
      points in this composite score vary from 1 to 10 points. Only those patients with a CPIS
      score of 6 or more were included in the study.

      For all patients included as study case following data was recorded: age, gender, clinical
      presentation, dates of admission and discharge. Time period of ICU stay prior to initiation
      of ventilation, duration of mechanical ventilation, duration of ICU and hospital stays were
      also recorded. Date of suspicion of VAP and number of episodes of VAP were also noted. Chest
      radiographs at the time of admission, on initiation of ventilation and at the time of
      clinical suspicion of VAP were also recorded.

      Specimen collection. With each episode of clinically suspected VAP, the patient was subjected
      to four different sampling techniques within 12 hours of clinical diagnosis of VAP with an
      average of an hour between each procedure. All procedures including bronchoscopy were
      performed by same investigator. A set sequence of sampling was followed in each case with the
      ETA first, followed by BBS, then blind BAL, and BAL at the last. All patients were
      premedicated with midazolam and fentanyl prior to performing these sampling procedures unless
      they were already sedated and paralyzed.

      Endotracheal Aspiration. Sterile suction catheters of 53 cm length (model GS 2006 Romsons,
      Agra, India) of sizes appropriate for the different sized endotracheal tubes were used. The
      catheter connected to mucus trap unit (model GS 51800, Romson, Agra, India) was advanced
      through the ETT till some resistance was encountered and after withdrawing about 1-2 cm,
      suctioning was performed and the aspirate collected in a sterile mucus trap. During this
      procedure the patient was temporarily disconnected from the ventilator with mean duration of
      10 seconds.

      Blind Bronchial Sampling. Blind bronchial sampling was performed using sterile catheter 2
      sizes smaller than ETA catheter. For 4.0 size ETT, 6 Fr size suction catheter was used.
      Catheter was introduced and advanced into the ETT blindly to the length around 5 cm greater
      than the length of ETT tube at the lip level. To increase the chances of placing the suction
      tube in the affected lung, the patient's head was turned to the opposite side in cases where
      infiltrates were unilateral. No saline was injected before or during the procedure. The
      procedure was repeated 2-3 times to obtain sample.

      Blind Bronchoalveolar lavage. Patients were preoxygenated for 5-10 minutes with 100% oxygen
      and sterile, disposable swivel adapter was inserted between ETT tube and ventilator circuit.
      Thus, all the patients received ventilation during the procedure. The catheter used for
      performing the blind BAL was a balloon tipped wedge pressure catheter (Model A1- 07121, Arrow
      International, PA 19605, USA). This was 60cm in length, 4Fr, double lumen with inflatable
      balloon of 0.6 mL capacity at the distal end. The length of the catheter was primed and
      filled with saline before insertion. The catheter was introduced into the ETT tube via swivel
      adapter's small opening and advanced much further than the length of the ETT from the lip
      level till resistance met. To increase the chances of obtaining lavage from affected lung,
      head turning maneuver was used as described previously. The distal balloon was inflated with
      1.0mL of normal saline since fluid is less compressible than air. Attempt was also made to
      wedge the catheter properly by further pushing it if possible. The volume of saline aliquot
      injected through catheter varied with the weight of the child. We used 3 mL for babies less
      than 5 Kg, 5 mL for children between 5 - 10 Kg, 7.5 mL for 11- 20 Kg and 10 mL for patients
      above 20 Kg. An aliquot of sterile saline was injected over 10 seconds and immediately
      reaspirated into the syringe attached to the 3-way of the catheter. Four such separate
      aliquots were used without withdrawing the catheter and using 4 different syringes. The first
      syringe aspirate was discarded while other 3 samples were collected in a sterile mucus trap.

      Bronchoscopic bronchoalveolar lavage. Before starting BAL, all patients were pre-oxygenated
      with 100% oxygen for 5-10 minutes. The site for bronchoscopic BAL was chosen according to the
      x-ay appearance. BAL was thus performed in an area of localized pulmonary infiltration if
      present. In case the chest x-ray showed diffuse disease or no specific area with infiltrate,
      BAL was performed in the area with most inflammation or with purulent secretions. If no
      inflammation or purulent secretions were seen during bronchoscopy, BAL was performed in the
      right lower or middle lobe. All bronchoscopic lavages were obtained with Olympus BF type XP40
      bronchoscope (Olympus Optical Co. Japan) with outer diameter of 2.8mm and a suction channel
      of 1.2mm size. Endotracheal suction was done just prior to introduction of bronchoscope.
      Lignocaine spray was avoided as local anesthetic during the procedure. BAL was performed via
      the endotracheal tube using a swivel adapter. In infants with 4.5 or less endotracheal tube
      size, an appropriate size laryngeal airway mask was used for bronchoscopic lavage (24). Under
      visual control, the bronchoscope was advanced in the direction of the chosen segment until a
      wedged position was achieved. Lavage was carried out using 4 aliquots of sterile saline
      (depending on weight of the patient)

      All patients were monitored during and after all the four procedures with multiparameter
      monitor and any significant hypoxic episode (saturations dropping below 80) or cardiac
      arrhythmia were recorded as complications of the procedures. In 3 infants transient hypoxia
      was noticed during BBS procedure. This was corrected rapidly with bagging and the procedure
      was completed on second attempt using sterile disposable swivel adaptor providing continued
      ventilation.

      Microbiological methods. All the samples were transported to the laboratory within 15 minutes
      and cultured within an hour of collection. After receipt in the laboratory, the samples were
      first vortexed for 60 seconds after which, gram stained preparations were performed and
      studied for the presence of squamous cells, polymorphonuclear cells and the type of
      microorganism present. The presence of polymorphonuclear cells (PMN) in the aspirated fluid
      was semi-quantified using techniques published previously (25). Simultaneously, quantitative
      cultures using the calibrated loop method were performed on common media such as blood agar,
      chocolate agar and Mckonky's agar using standard techniques (26). Organisms were identified
      using automated Vitek - 1 system (bioMerieux, France). Microbiological examination for
      unusual organisms such as Mycoplasma, Chlamydia, Pneumocystis carinii and viruses did not
      form a part of this study.

      The institutional review board approval was obtained for the study and informed consent for
      all diagnostic procedures was taken from the parents.

      Statistical analysis. In accord with previous studies (1, 14, 15, 21, 22) of quantitative
      bacteriology of BAL cultures, a bacterial density of >104cfu/ml was considered as 'POSITIVE'
      for VAP and those episodes were referred to as 'DEFINITE VAP' episodes. The organisms
      isolated on blood culture were compared against the organisms isolated from the cultures of
      various tracheobronchial techniques using the chi square test. Analysis was also done for any
      relation between the semi-quantitation of PMN on gram stain and cultures of the lower
      tracheobronchial secretions. Taking BAL colony counts of ≥ 104 cfu/ml as the reference
      standard, the other three methodologies - ETA, BBS and blind BAL were analyzed and their
      receiver operating curves (ROC) were plotted and the area under the curve were also obtained.
      Following this, the sensitivities, specificities, positive and negative predictive values
      (PPV, NPV) and accuracies at various cut off values of colony counts for all the above
      mentioned techniques were calculated. Concordance between different diagnostic methods was
      analyzed using kappa score. P value less than 0.05 was considered significant.

      DISCUSSION To our knowledge this is the first prospective study from a developing country
      comparing the four methods ( ETA, BBS, blind BAL, bronchoscopic BAL) for the diagnosis of
      VAP. Taking bronchoscopic BAL as the reference standard, the operative characteristics of the
      first three techniques at different threshold values of colony counts were worked out along
      with the microbiology of VAP.

      Pseudomonas aeruginosa was the most common organism to be isolated from the forty episodes of
      VAP.This finding is in agreement with other studies, which have stated the incidence of
      Pseudomonas VAP to be the highest among all pathogens. (14, 27, 28). A systematic analysis
      reported that gram negative bacteria represented 58% of the recovered organisms (1). Of
      these, most of the episodes were caused predominantly by Pseudomonas aeruginosa (24.4%),
      Enterobacteriaceae (14.1%), Acinetobacter (7.9%) while Staphylococcus aureus was reported in
      20.4% and Candida sps for 0.9% of the episodes of VAP.

      In the present study simplified CPIS was used because it is simple and can be used
      repeatedly. This includes readily available parameters indicating clinical, laboratory and
      oxygenation status of patient. This score has been extensively studied in adults. This score
      has the sensitivity ranging from 72 - 77% and the specificity varying from 58 - 85% for the
      diagnosis of VAP (29, 30). The use of this score has been reported once in a retrospective
      pediatric study in 40 cases (31). This study showed CPIS has a PPV of 93% and was also found
      to be an early predictor of poor prognosis. In present study the CPIS score was also
      evaluated against the reference standard at values of 7, 8, 9 and 10. It was found that the
      most accurate value of CPIS to diagnose DEFINITE VAP was between 7 and 8 with the area under
      the ROC being 0.812 (p value=0.001). The mean CPIS in patients with definite VAP was 8.4
      while in no definite VAP group it was 6.7 (p 0.007). In a study by Pugin et al (18), the cut
      off of 6 for CPIS was found to show a good correlation (r 0.84, p < 0.0001) between this
      clinical score and quantitative bacteriology of BAL samples.

      There was not a single instance when the BAL culture was positive with a corresponding
      negative endotracheal aspirate. ETA cultures yielded microorganisms in 37 episodes as
      compared to 29 by the reference standard and therefore only 29 episodes (78%) could be called
      definite VAP on endotracheal aspirates It has been shown that ETA has high sensitivity but
      low specificity for the diagnosis of VAP (22). So a sterile ETA assures the absence of VAP.In
      a study by Torres et al (32) of the 51 isolates on qualitative ETA only 29 (57%) correlated
      with same organisms growth on PSB (103 cfu/mL) and BAL (>103 cfu/mL). In another study (22)
      endotracheal secretions culture was positive in 70% of 30 pediatric cases. The concordance
      between reference standard (expert's opinion) and positive ETA was 57% (kappa 0.24). This
      high false positive rate in our as well as the studies cited above, could be explained by the
      bacterial colonization of the proximal airways observed in most patients in the ICU.

      In the present study threshold value for ETA of 105 cfu/mL appeared to be most accurate with
      kappa statistic of 0.631. This cut off value was similar to that obtained by El Ebiary et al
      (33) where protected specimen brush (PSB) (>103 cfu/mL) and BAL (>103 cfu/mL) were used as
      the reference standard.

      Blind bronchial sampling showed 88% sensitivity and 82% specificity at 104 cfu/mL (kappa
      0.68). Thus quantitative cultures of BBS appear to be simple, non invasive and useful tool in
      the diagnosis of VAP. The high accuracy of BBS is not unusual as VAP is usually secondary to
      the aspiration of colonized oro-pharyngeal secretions into the dependent areas of the lung
      (especially the right), which can easily be reached with a catheter passed blindly through
      the endotracheal tube (19). Papazian et al (30) showed the sensitivity of BBS (58%) was
      greater than that of PSB (42%) but less than that of BAL (93%) and the area under ROC of BBS
      was greater than that of PSB (p<0.05). The author concluded that BBS was preferable to PSB
      for the diagnosis of VAP.

      The blind BAL performed with wedge pressure catheter was most accurate at ≥ 103 cfu /ml
      (kappa 0.78) in the present study. Pugin et al (18) compared blind BAL results with
      bronchoscopic BAL. They calculated a sensitivity of 73% and a specificity of 96% and PPV of
      92% for blind non-bronchoscopic BAL. Gaussorgues etal (34) used 7 Fr right heart
      catheterization cuffed catheter for blind BAL in 13 adults and compared with postmortem lung
      tissue histology and culture. When lung histology and cultures were negative for pneumonia
      and organisms, the blind BAL were also negative for organisms on culture. Among the 10
      positive blind- BAL cultures, lung biopsy showed histologic pneumonia in 9 cases. Fourteen
      organisms were cultured from lung tissue while blind BAL correctly identified the causative
      microbes in 13 cases. Alpert etal (35) used 4 Fr balloon tipped wedged pressure catheter to
      perform blind BAL in 20 pediatric cases aged 1 month to 6.5 years. Clinically significant
      information was obtained in 17 (85%) cases and no patients required an open lung biopsy.
      Other innovative method for blind BAL using feeding tube in small children has been described
      by Koumbourlis etal (36).

      Strengths of the study. This prospective study included consecutive patients selected with
      strict criteria including simplified CPIS and not on the attending physician suspicion, so
      reducing the selection bias. All the diagnostic procedures were done in the same sequence in
      a predefined time period and by the same investigators. As it appears, BBS and blind BAL can
      be used for the diagnosis of VAP. In this study performance of blind BAL was best, followed
      closely by BBS when compared with bronchoscopic BAL as a reference standard for the diagnosis
      of VAP. The imported balloon tipped pressure catheter used in this study for blind BAL costs
      INR 1600.00 whereas suction catheter made in India used for BBS costs less than INR 10.00.
      This huge cost difference is definitely a major consideration in the PICU of developing
      countries while investigating VAP.

      Limitations of study. Lung tissue specimen is the best tool for the diagnosis of VAP (37) but
      not perfect as a gold standard (22). Lung tissue sample results may be negative if the
      patient is already on antibiotics and histological changes may be disseminated in the
      different segments of the lungs and not in a homogenous fashion (39). Studies have shown that
      sampling limited to one specimen from the lungs cannot exclude VAP (40, 41). Moreover the
      autopsy is difficult to use as gold standard in the pediatric population because of the
      mortality attributed to VAP is as low as 8% (42). In the present study the mortality due to
      VAP was 10%. In this study the bronchoscopic BAL culture (≥104cfu/mL) was used as reference
      standard. Compared with lung specimen cultures and histology, PSB (≥ 103 cfu/mL) and
      bronchoscopic BAL (≥ 104 cfu/mL) showed strong correlation in identifying the causative
      organisms (38). Moreover BAL appears to have an acceptable level of reproducibility of 75%
      (28). High concordance has been found for the presence (93%), type (86%) and quantity (78%)
      of bacteria in two protected BAL samples taken 2 hours apart (20).

      CONCLUSIONS The most common organism responsible for VAP in this study was Pseudomonas
      aeruginosa. Negative ETA culture rules out the diagnosis of VAP. Quantitative cultures of BBS
      and blind BAL were useful in the diagnosis of VAP at threshold of ≥ 104 cfu / mL and ≥ 103
      cfu / mL respectively. The role of BBS should be reevaluated in the future studies since it
      is cheap, easy to perform, well tolerated by ventilated children and can be repeated easily.

      Table 1- Baseline Characteristics of the study population (n= 30)

      No of VAP episodes 40 Age median (range) 6.5 years (1 mo -12 yrs) Males 20 (66.5%) PRISM
      score (range) 13 ± 6 (0 - 34) Primary system involvement Central nervous system 9 (30)
      Respiratory system 6 (20) Septicemia 5 (16.6) Diabetic ketoacidosis 2 (6.6) Postoperative
      status 2 (6.6) Trauma 2 (6.6) Miscellaneous 4 (13.3) Multiorgan dysfunction 15 (50) Use of
      steroids 4 (13.3) Immunosuppressed state 2 (20) Use of H2 blockers 9 (30) Central lines 30
      (100) Arterial lines 30 (100) Chest x-ray At admission Normal 21 (70) ARDS 3 (10) Others 6
      (20) At initiation of MV Normal 14 (44.6) ARDS 9 (30) Others 7 (23.3) CPIS mean ±SD (range)
      7.8 ± 1.5; 6 - 10

      Figures in parentheses indicate percentage unless mentioned

      Table 2 - Clinical characteristics of study cases on the day of lower respiratory tract
      aspirate collection (n= 30)

      No. of VAP episodes 40 Temperature °C a 38.9 ± 0.81 (36 - 40.2) TLC a 17995± 6840 (3200 -
      32700) PaO2 / FiO2a 185 ± 65.3 (112 - 320) Purulent tracheo- bronchial secretions Scanty 1
      Moderate 14 Profuse 25 Abnormal chest X-ray Collapse 21 Consolidation 8 B/L pulmonary
      haziness 6 ARDS 4 Cavitatory lesions 1 CPIS a (range) 7.8 ± 1.5 (6-10)

      a mean ± SD . Figures in parentheses indicate range

      Table 3 - Operative indices of simplified clinical pulmonary infection score for the definite
      diagnosis of ventilator associated pneumonia (Reference standard BAL colony counts of ≥ 104
      cfu / ml)

      CPIS Sensitivity Specificity PPV NPV Accuracy

      6 100 0 62.5 0 62.5

      7 88 60 78.5 75 77.5

      8 80 80 87 70.5 80

      9 61 87 87.5 54 67.5

      10 24 93 85.7 42 50

      Table 4 -. Relation between polymorhonuclear cells on Gram stain samples of lower respiratory
      tract aspirate obtained by different techniques with positive culture of BAL (≥104 cfu /ml)
      (n= 40 in each category)

      Technique Gram stain PMN a No. of BAL culture Contingency p value

        -  104 <104 coefficient

      Endotracheal Few 0 3 Aspirate Moderate 0 1 0.39 0.02 Many 25 11

      BBS Few 0 3 Moderate 1 2 0.38 0.02 Many 24 10

      Blind BAL Few 1 6 Moderate 3 2 0.42 0.03 Many 21 7

      BAL Few 0 7 Moderate 2 1 0.51 0.003 Many 23 7

      a Reference 25

      Table 5. Microorganisms cultured from different lower respiratory tract aspiration techniques
      ( n= 40 in each category)

      Organisms ETA BBS Blind BAL BAL

      Pseudomonas aeruginosa 17 15 13 13 Acinetobacter baumannii 9 7 7 6 Klebsiella pneumoniae 6 5
      2 5 Enterobacter species 5 4 4 4 MRSA 3 2 4 2 Proteus mirabilis 1 1 1 1 Escherichia coli 2 0
      0 0 Candida species 3 3 3 3

      Number of isolates exceeds no. of aspirates due to polymicrobial growth

      Table 6. Operative indices of three sampling methods for the diagnosis of definite ventilator
      associated pneumonia compared with reference standard (BAL colony counts ≥104 cfu / mL)

      Technique cfu / mL Sensitivity Specificity PPV NPV Accuracy

      Endotracheal >103 100 27 69 100 72.5 Aspirate >104 96 60 80 90 81 >105 84 77 87.5 73 80 >106
      8 100 100 39.5 42.5

      BBS >102 100 60 81 100 85 >103 100 73 86 100 85 >104 88 82 88 83 87 >105 8 100 100 39.5 42.5

      Blind BAL >102 96 73 86 91.6 87.5 >103 96 80 88 92.3 90 >104 32 100 100 47 57.5

      A B

      C D Figure 1. Receiver operative curves depicting the relation between reference standard BAL
      culture colony count ≥ 104 cfu/ ml and (A) CPIS (AUC 0.81± 0.06, p = 0.001), (B) ETA ( AUC
      0.87± 0.06,p = 0.00), (C) BBS (AUC 0.89± 0.06, p= 0.01), (D) blind BAL ( AUC 0.89± 0.05, p=
      0.00).

      AUC- Area under curve
    

Intervention name(s): bronchoaleolar lavage; Bronchoscopy
Intervention type(s): Procedure; Procedure
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic
Keywords: Mechanical ventilation, Ventilator- associated pneumonia, Bronchoalveolar lavage, Pediatric intensive care unit, Flexible bronchoscopy, Critical care