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Correspondence |

Ultrasound Diagnosis of Ventilator-Associated Pneumonia: A Not-So-Easy Issue FREE TO VIEW

Marco Sperandeo, MD; Paola Filabozzi, MD; Vincenzo Carnevale, MD
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FINANCIAL/NONFINANCIAL DISCLOSURES: None declared.

CORRESPONDENCE TO: Marco Sperandeo, MD, Unit of Interventional and Diagnostic Ultrasound of Internal Medicine, “Casa Sollievo Della Sofferenza” Hospital, IRCCS, Viale dei Cappuccini 1, 71013 San Giovanni Rotondo (FG), Italy


Copyright 2016, American College of Chest Physicians. All Rights Reserved.


Chest. 2016;149(5):1350-1351. doi:10.1016/j.chest.2016.02.684
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In an article recently published in CHEST (April 2016), Mongodi et al investigated the fascinating hypothesis that, as in community-acquired pneumonia, thoracic ultrasonography (TUS) could also be a reliable complementary diagnostic tool in ventilator-associated pneumonia (VAP).

This study raises some relevant concerns. First, because of the anatomical constraints of the thoracic cage, TUS can at best explore about 70% of the pleural surface, and even in zones amenable to TUS examination, only lesions adherent to the pleural surface may be visualized. This partly explains the overall rather low sensitivity of TUS in the current study. In actuality, as also stated by the authors, because of the positive pressure generated by mechanical ventilation, the foci of bronchopneumonia in VAP tend to spread to the periphery; but, again, they are detectable by TUS only when adherent to the pleural surface. This could in turn result in a lower sensitivity of TUS in VAP as compared with community-acquired pneumonia. Sonographic patterns of subpleural abnormal aeration are frequently observed in patients mechanically ventilated for various diseases. Other conditions reducing lung aeration may be alternatively or concomitantly present in critically ill, mechanically ventilated patients, such as elevated diaphragm and atelectasis, atypical pulmonary edema, pulmonary hemorrhage, thromboembolism, drug reaction, and ARDS. All these conditions share common sonographic patterns, and each picture is further compounded by comorbidities, so that TUS features cannot be considered disease-specific. In addition, the authors lay particular emphasis on the results concerning “linear/arborescent bronchograms.” However, it should be stressed that no study or meta-analysis has so far demonstrated that such hyperechoic images do really correspond to the CT imaging finding of air bronchogram. Instead, we have shown that such images can also be detected in lung neoplasm masses (Fig 1). Moreover, according to our experience, it seems difficult to obtain reliable and repeatable results by synchronizing a TUS scan with mechanically induced inspiration, particularly when different operators are involved.

Figure Jump LinkFigure 1 Ultrasonographic pattern of a lung neoplasm (biopsy-proven undifferentiated carcinoma), including hyperechoic spots and/or bands, improperly called an air bronchograms (blue arrow) (A) and the corresponding CT image (B).Grahic Jump Location

It is worth noting that the authors do not report relevant technical aspects, which may significantly affect their results. In fact, in this multicentric study, no information is provided about the expertise and specific TUS training of the operators and their interobserver agreement, the ultrasound devices employed and their respective settings, or the probes used, all of which may affect the ultrasonographic pattern of a lesion. Last, the authors do not specify the position of the patients during TUS examination.

References

Mongodi S. .Via G. .Girard M. .et al Lung ultrasound for early diagnosis of ventilator-associated pneumonia. Chest. 2016;149:969-980 [PubMed]journal. [CrossRef] [PubMed]
 
Sperandeo M. .Carnevale V. .Muscarella S. .et al Clinical application of transthoracic ultrasonography in inpatients with pneumonia. Eur J Clin Invest. 2011;41:1-7 [PubMed]journal
 
Reissig A. .Gorg C. .Mathis G. . Transthoracic sonography in the diagnosis of pulmonary diseases: a systematic approach. Ultraschall Med. 2009;30:438-454 [PubMed]journal. [CrossRef] [PubMed]
 
Berlet T. .Etter R. .Fehr T. .Berger D. .Sendi P. .Merz T.M. . Sonographic patterns of lung consolidation in mechanically ventilated patients with and without ventilator-associated pneumonia: a prospective cohort study. J Crit Care. 2015;30:327-333 [PubMed]journal. [CrossRef] [PubMed]
 
Sperandeo M. .Rotondo A. .Guglielmi G. .Catalano D. .Feragalli B. .Trovato G.M. . Transthoracic ultrasound in the assessment of pleural and pulmonary diseases: use and limitations. Radiol Med. 2014;119:729-740 [PubMed]journal. [CrossRef] [PubMed]
 

Figures

Figure Jump LinkFigure 1 Ultrasonographic pattern of a lung neoplasm (biopsy-proven undifferentiated carcinoma), including hyperechoic spots and/or bands, improperly called an air bronchograms (blue arrow) (A) and the corresponding CT image (B).Grahic Jump Location

Tables

References

Mongodi S. .Via G. .Girard M. .et al Lung ultrasound for early diagnosis of ventilator-associated pneumonia. Chest. 2016;149:969-980 [PubMed]journal. [CrossRef] [PubMed]
 
Sperandeo M. .Carnevale V. .Muscarella S. .et al Clinical application of transthoracic ultrasonography in inpatients with pneumonia. Eur J Clin Invest. 2011;41:1-7 [PubMed]journal
 
Reissig A. .Gorg C. .Mathis G. . Transthoracic sonography in the diagnosis of pulmonary diseases: a systematic approach. Ultraschall Med. 2009;30:438-454 [PubMed]journal. [CrossRef] [PubMed]
 
Berlet T. .Etter R. .Fehr T. .Berger D. .Sendi P. .Merz T.M. . Sonographic patterns of lung consolidation in mechanically ventilated patients with and without ventilator-associated pneumonia: a prospective cohort study. J Crit Care. 2015;30:327-333 [PubMed]journal. [CrossRef] [PubMed]
 
Sperandeo M. .Rotondo A. .Guglielmi G. .Catalano D. .Feragalli B. .Trovato G.M. . Transthoracic ultrasound in the assessment of pleural and pulmonary diseases: use and limitations. Radiol Med. 2014;119:729-740 [PubMed]journal. [CrossRef] [PubMed]
 
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