The Radiologic Diagnosis of Autopsyproven Ventilator-associated Pneumonia

doi:10.1378/chest.101.2.458

Chest

Volume 101, Issue 2, February 1992, Pages 458-463

https://doi.org/10.1378/chest.101.2.458 Get rights and content

An abnormal chest roentgenogram is essential for the diagnosis of ventilator-associated pneumonia. The diagnostic accuracy of various roentgenographic signs of pneumonia has not been assessed previously in the portable anteroposterior roentgenograms obtained in ventilated patients. Seven roentgenographic signs (air bronchograms, alveolar infiltrates, silhouette sign, cavities, fissure abutment, atelectasis, and asymmetric infiltrates superimposed on diffuse bilateral infiltrates) were evaluated for their accuracy in predicting pneumonia alone, in combination with other signs, or in combination with clinical parameters. The last roentgenogram prior to autopsy of 69 ventilated patients was interpreted by three reviewers and the above signs were correlated with autopsy evidence of pneumonia. Pneumonia was present in 24 (35 percent) of the 69 autopsies. No roentgenographic sign had a diagnostic efficiency of greater than 68 percent. By stepwise logistic regression, the presence of air bronchograms was the only roentgenographic sign that correlated with pneumonia in the total group, correctly predicting 64 percent of pneumonias. In patients without adult respiratory distress syndrome (ARDS), the presence of air bronchograms or alveolar infiltrates correlated with pneumonia, while in patients with ARDS, no roentgenographic sign and only the clinical parameter of purulent sputum correlated with pneumonia. Only a minority (7/22) of worsening alveolar infiltrates in all groups were due to pneumonia and were often confused with ARDS. Alveolar hemorrhage occurred with a surprising frequency (38 percent of autopsies), including 13/45 (29 percent) patients without pneumonia. Alveolar hemorrhage was associated with 29 percent of multiple air bronchograms and 30 percent of bilateral alveolar infiltrates in patients without pneumonia. We conclude that in intubated patients with diffuse bilateral roentgenographic infiltrates, no roentgenographic sign correlates well with pneumonia. No clinical parameter added to the accuracy of either an alveolar infiltrate or an air bronchogram in patients without diffuse infiltrates. Pulmonary hemorrhage and/or infarction are frequent autopsy findings in intubated patients and may be confused radio-logically with pneumonia.

Section snippets

Patient Selection

Autopsy records for the period January 1, 1985 to June 30, 1988 were reviewed. Patients were included in this study if they had received at least 12 h of mechanical ventilation prior to death and had at least two chest roentgenograms while receiving mechanical ventilation. Patients were excluded if chest roentgenograms had been microfilmed and destroyed (three patients), if charts were unavailable for review (three patients), or if incomplete autopsies had been performed (three patients). After

RESULTS

Twenty-four (35 percent) of the 69 patients had pneumonia present at autopsy (Table 1). Early ARDS, as confirmed by hyaline membranes, was present in 16 patients (23 percent). Twenty patients had pulmonary infarction. Only two of these patients had a thrombus present in the pulmonary artery at time of autopsy. Twenty-six patients were found to have either gross or microscopic pulmonary hemorrhage, ten of whom had an associated pulmonary infarction. An additional 16 patients had pulmonary

DISCUSSION

A new or changing roentgenographic infiltrate is required by practically all studies of pneumonia, as well as most clinical diagnoses.5, 6, 7, 11, 12, 13 Very few studies, however, have examined the accuracy of the portable chest roentgenograph in the intensive care unit (ICU). Bryant et al¹² reviewed clinical findings and chest roentgenograms in 60 surgical ICU patients suspected of having pneumonia. Only 18 (30 percent) of the 60 patients were ultimately found to have pneumonia definitely.

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Chest

Clinical InvestigationsThe Radiologic Diagnosis of Autopsyproven Ventilator-associated Pneumonia

Section snippets

Patient Selection

RESULTS

DISCUSSION

Clin Chest Med

Chest

Chest

Intensive care unit radiology: problems of interpretation

Radiol Clin North Am

Cardiopulmonary disorders in the critically ill

Localization of intrathoracic lesion

Diagnosis of nosocomial pneumonia in intubated, intensive care unit patients

Am Rev Respir Dis

The radiologic distinction of cardiogenic and noncardiogenic edema

AJR

Clinical Investigations
The Radiologic Diagnosis of Autopsyproven Ventilator-associated Pneumonia