Abstract
IntroductionVentilator-associated respiratory infection (VARI) is an important cause of morbidity in critically-ill patients. Clinical trials performed in heterogeneous populations have suggested there are limited benefits from invasive diagnostic testing to identify patients at risk or to target antimicrobial therapy. However, multiple patient subgroups (for example, immunocompromised, antibiotic-treated) have traditionally been excluded from randomization. We hypothesized that a prospective surveillance study would better identify patients with suspected VARI (sVARI) at high risk for adverse clinical outcomes, and who might be specifically targeted in future trials.MethodsWe performed a prospective observational study in all patients ventilated for greater than 48 hours. sVARI was identified by surveillance for changes in white blood cell count, temperature, sputum, and/or new chest X-ray infiltrates. Indices of disease co-morbidity, as well as mortality, duration of mechanical ventilation, and length of hospital or ICU stay were correlated with sVARI.ResultsOf 1806 patients admitted to the ICU over 14 months, 267 were ventilated for greater than 48 hours, and 77 developed sVARI. Incidence of sVARI was associated with iatrogenic immunosuppression or admission for respiratory illness. Any sVARI, whether suspected ventilator-associated pneumonia (sVAP) or ventilator-associated tracheobronchitis (sVAT), was associated with increased length of stay and duration of mechanical ventilation.ConclusionsClinical surveillance for sVARI identifies patients at risk for increased morbidity. Iatrogenically immunosuppressed patients, a subgroup previously excluded from randomized clinical trials, represent a growing proportion of the critically-ill at risk for sVARI who might be targeted for future investigations on diagnostic or therapeutic modalities.
Highlights
Ventilator-associated respiratory infection (VARI) is an important cause of morbidity in critically-ill patients
Immunosuppressed patients, a subgroup previously excluded from randomized clinical trials, represent a growing proportion of the critically-ill at risk for suspected VARI (sVARI) who might be targeted for future investigations on diagnostic or therapeutic modalities
Ventilator-associated respiratory infection (VARI), which includes ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT), is a common acquired infection in the ICU that contributes to excess length of stay, duration of ventilation, cost and likely mortality [1,2]
Summary
Ventilator-associated respiratory infection (VARI) is an important cause of morbidity in critically-ill patients. Clinical trials performed in heterogeneous populations have suggested there are limited benefits from invasive diagnostic testing to identify patients at risk or to target antimicrobial therapy. Quantitative cultures of lower respiratory tract samples resulted in reduced mortality, antibiotic use and organ failure [5]. A systematic review based on these, and two other small clinical trials [7,8,9,10], suggested that there is no effect of invasive sampling or quantitative cultures on mortality in patients with suspected VAP. The trials excluded the majority of screened patients, or those patients with risk factors commonly encountered in contemporary quaternary care ICUs (for example, iatrogenic immunosuppression, previous bacterial colonization, concurrent use of broad spectrum antibiotics)
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