Determining treatment effectiveness and period of treatment

SUMMARY • Judging the effect of treatment for hospital‐acquired pneumonia is difficult using only inflammatory parameters or findings from chest radiography. • Preferably, treatment effects should be judged comprehensively from body temperature, findings of chest radiography, inflammatory parameters, status of purulent discharge, bacteriological findings and oxygenation. • In VAP, the parameter most closely correlated with prognosis is trend in PaO 2 /FiO 2 . • Clinical improvements are normally seen within 72 h. Antimicrobials thus should not be changed until the third day unless a dramatic deterioration in symptoms is seen. • With the exception of pneumonia from microbes that tend to possess strong resistance, such as Pseudomonas aeruginosa , a treatment period of 7–10 days is adequate if the early‐stage drugs are effective. • If no improvements in the course are achieved by 3 days after starting treatment, an investigation should be made into whether treatment should be continued or changed to a different antimicrobial agent.