The utility of a modified technique for lower respiratory tract sampling in COVID-19 ICU and review of diagnostic approaches in suspected ventilator associated pneumonia
INTRODUCTION: Lower respiratory tract (LRT) sampling is an aerosol generating procedure. In COVID 19 pandemic, guidelines have advocated caution against all aerosol generating procedures. However, microbial cultures on tracheobronchial aspirates are important to guide antibiotic usage in ventilator-associated pneumonia (VAP). MATERIAL AND METHODS: In our tertiary care COVID-19 intensive care unit (ICU), a protocol was set for using closed suction system for timely LRT sampling in VAP and to reduce the risk of exposure to respiratory secretions. Timing of sample collection was as per intensivist discretion following CDC VAP definition. This prospective study was conducted between June to November 2020, to assess the utility of this technique in diagnosis of suspected VAP. Microbiological and clinico-radiological parameters were documented. Heavy growth (>105 cfu/mL) on semiquantitative culture was taken as significant. RESULTS: Total 69 samples generated from 63 patients were analyzed. Mean age 54.48 years and 77.78% of patients had one or more comorbidities. Average duration of invasive ventilation prior to the first culture was 7.14 ± 4.36 days. Progressive radiological worsening at the time of sample collection was in 92.75% (64 of 69 episodes). Microbiological diagnosis of VAP was confirmed in 76.81%. Culture reports guided antibiotic change. Insignificant culture growth in 13.06%. The positivity rate for early and late (>4days) samples were 69.56% and 80.43% respectively. 95% of culture isolates were Gram negative microorganisms. Most common being Acinetobacter baumannii (41.67%) and Klebsiella pneumoniae (31.66%) in both early and late VAP. Around 85% were multidrug resistant organisms. There were no significant adverse events related to sampling technique. CONCLUSIONS: Lower respiratory tract sampling using closed suction system is easy to execute and minimizes procedure related risk to both patient and health care workers in COVID-19 ICU. Gram negative MDR pathogens are prevalent in both early and late VAP. Need further comparative study to understand effectiveness of this technique against other conventional techniques in VAP diagnosis
