Determining treatment effectiveness and period of treatment

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.