Surveillance and evaluation of ventilator-associated events as per Centers for Disease Control and Prevention guidelines

Introduction

While ventilator-associated pneumonia (VAP) can affect all patients ventilated for >2 days in an ICU, an issue during the last two decades has been identification of a universally accepted definition. The Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA, have designed a new surveillance paradigm aiming to increase the objectivity of VAE diagnosis ranging from ventilator-associated condition (VAC), infective VAC to possible and probable VAP [1]. We assessed the feasibility and accessibility of the audit tool developed from the CDC guidelines as a marker of quality assurance.

Methods

A prospective audit of patients admitted to University Hospital Lewisham ICU for intubation and ventilation was performed for September and October 2013. Recording of minimum PEEP and FiO₂, minimum and maximum temperatures, WBC count, specimens sent, antibiotics administered and date of organisms found was performed on a daily basis. VAEs were recorded as per modified CDC criteria (absence of quantitative microbiological testing) and compared against a surrogate marker of clinically diagnosed VAEs based on information available to the clinician.

Results

Forty patients were admitted with 29 fulfilling inclusion criteria. Of n = 29, mean age was 58 (SD 21) with a median number of 5 (2 to 29) ventilator-days. We recorded eight VAEs based on CDC criteria, one VAC, four IVAC and three VAPs. Clinical decision-making indicated seven VAEs, of which five were VAPs. CDC and clinical criteria correlated in only five of eight VAPs and clinical criteria alone would have indicated 40% more VAPs than CDC criteria. Median time to VAE trigger was 8 days (4 to 20), median number of ventilator-days if a CDC VAE triggered was 14 compared with 3 if no CDC VAE was triggered (P < 0.01), and 11 compared with 3 (P < 0.01) for clinical VAEs.

Conclusion

While similar numbers of VAEs are triggered using CDC and clinical criteria, we noted a disparity in the VAP incidence. Four clinical VAPs were not triggered due to the hierarchical nature of the CDC criteria because the initial criterion of sustained minimum PEEP or FiO₂ rise was not met despite clear clinical criteria based on increased inflammatory markers, temperature spikes and new microbiology. We are therefore doubtful of the robustness of this tool in its current format as an accurate measure of quality assurance and agree with recent statements from the CDC [1] that modifications may be necessary.