Evaluation of Non-responding Patients with Ventilator-associated Pneumonia

Abstract

The high incidence and mortality rate of ventilator-associated pneumonia (VAP) mandate an early and aggressive assessment of the clinical evolution in order to detect the causes of nonresponse to empirical antibiotic treatment. Persistence of the initial clinical manifestations (fever, purulent tracheal secretion, leukocytosis), progression of the radiographic infiltrate, or lack of improvement of the gas exchange are the main criteria to define the failure to respond to treatment, at 72 hours of evolution. Monitoring other parameters of organ dysfunction, such as creatinine, bilirubin, and platelet count, may be useful for detecting and correcting concomitant disorders. The first approach to the nonresponding patient with VAP should be the evaluation of the spectrum and dosage of the antibiotic treatment. Resistant strains (i.e., methicillin-resistant Staphylococcus aureus) or unusual microorganisms (fungi, Legionella, cytomegalovirus), which are not covered by the routine therapy, need to be taken into account. Other concomitant infections should be considered in the case of persistent fever or systemic inflammatory response syndrome, such as sinusitis, empyema, lung abscess, vascular catheter-related sepsis, urinary infection, or abdominal sepsis. Other noninfectious conditions could mimic or complicate VAP, such as acute respiratory distress, atelectasis, bronchiolitis obliterans with organizing pneumonia, drug-related fever, or postpneumonectomy pulmonary edema. Investigations to be performed in nonresponding patients with VAP must be directed toward the diagnosis of these alternative conditions, and should rely on bronchoscopy, ultrasound, CT scan, echocardiography, and pulmonary scintigraphy.