Among the 53% of patients with negative bronchoalveolar lavage results, alternative explanations for fever and for pulmonary infiltrates were established in 61% and 46%, respectively.
Chest x-ray abnormalities, leukocytosis, purulent tracheal aspirate, or fever in a mechanically ventilated patient raise suspicion for ventilator-associated pneumonia (VAP), but specificity for each of these findings is poor. Nonbacterial infections and even noninfectious inflammatory processes can mimic VAP. Recent research has demonstrated that bronchoalveolar lavage (BAL) has better sensitivity and specificity for diagnosing VAP, ranging from 75% to 85%. But how frequently is suspected VAP not confirmed by BAL, and what are the alternative diagnoses?
Researchers in the Netherlands addressed this issue in a retrospective study involving 207 patients with suspected VAP according to clinical criteria. Of these, 110 (53%) had negative BAL results.
Intensive workup, including repeated BAL, radiographic studies, virologic assays, cultures, and pathologic examinations, revealed alternative explanations for fever in 67 (61%) of the 110 patients. These included bacteremia in 9 patients, pneumonitis caused by nonbacterial pathogens (e.g., herpes simplex virus-1, cytomegalovirus) in 10, resorption fever in 8, ischemia in 6, malignancy in 4, bronchiolitis obliterans with organizing pneumonia in 3, and drug-induced pneumonia in 3. Alternative diagnoses explaining pulmonary infiltrates, established in 51 (46%) of the patients, included congestive heart failure in 16, nonbacterial infectious pneumonia in 10, noninfectious pneumonitis in 10, and atelectasis in 7. In 43 patients (39%), no alternative explanation for either fever or pulmonary abnormalities could be found.
This study highlights the various diagnoses that need to be considered in a ventilated patient if suspected bacterial VAP is not supported by BAL results. Such diagnostic efforts are important because they help to avoid unnecessary antibiotic exposure and guide appropriate treatment.
VAP in intubated patient
Schoemakers RJ et al. Alternative diagnosis in the putative ventilator-associated pneumonia patient not meeting lavage-based diagnostic criteria. Scand J Infect Dis 2014 Sep 19