Pneumonia, Ventilator-Associated
Conditions
Brief summary
The purpose of this study is to assess microbiologic concordance rates between right- and left-lung bronchoalveolar lavage cultures from patients with suspected ventilator-associated pneumonia, identify predictors of concordance, and evaluate the impact of discordant microbiology on clinicians' ability to prescribe appropriate antibiotic treatments, the investigators conducted a prospective observational study in the general intensive care unit of a large university hospital.
Detailed description
Bronchoscopic sampling of lower respiratory tract secretions is widely used in intensive care units (ICUs) for the microbiological diagnosis of ventilator-associated pneumonia (VAP). However, the importance of selecting a specific lung segment for sampling is still a matter of debate. Non-bronchoscopic blind mini-bronchoalveolar lavage (BAL) is currently used for the diagnosis of VAP with satisfactory sensitivity and specificity. In the presence of pneumonia, microbiologic concordance between the left and right lungs becomes crucial. If concordance is low, the reliability of blind sampling becomes questionable. When the bacterial distribution in the right and left lungs of VAP patients has been investigated using bronchoscopic sampling techniques, rates of microbiological concordance between the two specimens have varied widely (from 53% to 92%). The factors potentially associated with concordant culture yields have never been explored, and it is unclear whether the use of guided, bilateral lung sampling would actually improve the appropriateness of the antibiotic regimens prescribed for patients with suspected VAP. The primary objective of this study is to assess the frequency of microbiologic concordance between the right- and left-lung samples in ICU patients undergoing bronchoscopic BAL performed with two different fiberoptic bronchoscopes for the suspicion of VAP. Secondary objectives are to identify factors associated with such concordance and to evaluate the suitability of treatments prescribed based on unilateral vs. bilateral BAL cultures.
Interventions
PROCEDUREBilateral BAL
Sponsors
Catholic University of the Sacred Heart
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* invasive mechanical ventilation of ≥ 48 hours * clinically suspected pneumonia (simplified Clinical Pulmonary Infectious Score exceeded 6 or chest radiographs with a new or progressive pulmonary infiltrate in a patient with at least two of the following: purulent respiratory secretions, temperature \>38°C or \<36°C, white blood cell count \>12,000/mm3 or \<4,000/mm3)
Exclusion criteria
* age \<18 years * pregnancy * absence of informed consent * an arterial oxygen partial pressure to inspired oxygen fraction ratio (PaO2:FiO2) of ≤150 * use of positive end-expiratory pressure (PEEP) \>10 cmH2O * active uncontrolled bronchospasm * unstable angina or recent (\<6 weeks) myocardial infarction * unstable arrhythmia * intracranial hypertension * platelet count ≤20,000/mm3 * international normalized ratio (INR) or activated partial thromboplastin time (aPTT) ratio \>1.5 * documented treatment-limitation orders in the patient's chart
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Rate of microbiologic concordance between the right- and left-lung samples | After at least 48 hours of invasive mechanical ventilation | Pneumonia is microbiologically confirmed when the quantitative culture of one or both BAL specimens is positive at significant growth for at least one potential bacterial pathogen. Right and left BAL cultures are classified as concordant when both are positive for the same organism(s) or when neither show any growth. Cultures are classified as discordant when at least one of the microorganisms isolated from one specimen is not recovered from the contralateral specimen. |
Secondary
| Measure | Time frame |
|---|---|
| Possible association between purulent secretions and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between duration of mechanical ventilation and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between duration of ICU stay and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between duration of hospital stay and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between immunosuppression and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between antibiotic treatment and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between radiological infiltrate and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between WBC count and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between PaO2:FiO2 and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between PEEP and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between CPIS and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between type of humidification and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between procalcitonin and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between C-reactive protein and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
| Possible association between body temperature and microbiologic concordance between right- and left-lung BAL cultures | At an expected average of 48 hours after bronchoscopy |
Other
| Measure | Time frame | Description |
|---|---|---|
| Comparison of antibiotic regimens chosen on the basis of right or left-lung culture results alone with regimens chosen on the basis of bilateral culture results, by performing a simulated prescribing experiment. | At 18 months after study initiation | For each enrolled patient, actual treatment decisions are made by the ICU attending physicians in charge of the case on the basis of the results of bilateral BAL culture and sensitivity analyses. Later, at the end of the study, data for patients with discordant BAL cultures are reviewed in a simulated prescribing session by a second team composed of an ICU physician and an infectious disease specialist. The team is asked to propose an appropriate antimicrobial regimen based on the culture and in vitro antimicrobial susceptibility data for the right-lung BAL sample alone, the left-lung BAL sample alone, and the right and left BAL samples. Each microbiological report is presented separately to the team with a summary of the patient's relevant clinical data. The prescribed regimen is defined as appropriate if it provides active coverage for all of the organisms identified in both BAL specimens. |
Outcome results
None listed