- Email: [email protected]
Chest Ultrasonography as a Replacement for Chest Radiography for Community-Acquired Pneumonia
clinical sequelae and support a higher threshold for “meaningful” desaturation such as Spo2 , 90%. It would be useful to know whether milder desaturation to this level can predict the development of symptoms during flight, and consideration could be given to reanalyzing the study’s results to find out. This may reinforce and broaden the authors’ conclusions—perhaps clinically significant hypoxemia is even more common than reported, and evaluation for supplementary in-flight oxygen should be even more widely advocated. Thomas G. Smith, MBBS, DPhil Oxford, England Affiliations: From the Nuffield Division of Anaesthetics, University of Oxford. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Thomas G. Smith, MBBS, DPhil, Nuffield Division of Anaesthetics, University of Oxford, Level 6, West Wing, John Radcliffe Hospital, Oxford, OX3 9DU, England; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2619
References 1. Roubinian N, Elliott CG, Barnett CF, et al. Effects of commercial air travel on patients with pulmonary hypertension. Chest. 2012;142(4):885-892. 2. Smith TG, Talbot NP, Chang RW, et al. Pulmonary artery pressure increases during commercial air travel in healthy passengers. Aviat Space Environ Med. 2012;83(7):673-676. 3. Smith TG, Chang RW, Robbins PA, Dorrington KL. Commercial air travel and in-flight pulmonary hypertension. Aviat Space Environ Med. 2013;84(1):65-67.
Response To the Editor: We thank Dr Smith for his thoughtful comments regarding our recent publication in CHEST (October 2012).1 We took great interest in his recently published findings demonstrating an increase in estimated pulmonary artery pressures in healthy air passengers without hypoxemia.2 In our study, we used an a priori-defined oxygen desaturation value of pulse oxygen saturation (Spo2) , 85% (corresponding to partial pressure of oxygen in the blood of approximately 50 mm Hg at sea level). We chose this value to maintain a high specificity for oxygen desaturation events, consistent with this being the recommended threshold for prescribing in-flight supplemental oxygen in individuals, based on altitude simulation testing.3 We agree that a more sensitive threshold for oxygen desaturation may correlate better with flight symptoms and/or pulmonary vasoconstriction events. Using our original threshold of Spo2 , 85%, we did not find a significant association between desaturation events and flight symptoms (P 5 .25). However, we did find that the oxygen saturation nadir was lower in individuals with flight symptoms compared with those without symptoms (Spo2, 85% vs 89%; P 5 .03). Notably, even when using this more restrictive cutoff for Spo2 of 85%, there were four subjects who remained asymptomatic despite desaturation events. Using a more sensitive threshold of oxygen desaturation (Spo2 , 88%), we found a significant association with flight sympjournal.publications.chestnet.org
Downloaded From: http://journal.publications.chestnet.org/ on 03/07/2013
toms (P , .01) and a similar number of individuals with asymptomatic oxygen desaturation. When the threshold was further increased (Spo2 , 90%), we saw an even stronger association with flight symptoms, but there was also a substantial increase in the number of individuals with asymptomatic oxygen desaturation by this definition. Therefore, a cutpoint of Spo2 , 88% appeared to have the best performance characteristics with respect to reported symptoms. Dr Smith’s findings, taken together with our study results, imply that even under mildly hypoxic conditions, individuals with underlying pulmonary vascular disease may experience symptoms as a result of elevations in pulmonary artery pressure.1,4 Further studies are needed to better understand the relationship between changes in pulmonary artery pressures, symptoms, and desaturation events during flight, and their implications with regard to air travel safety for patients with pulmonary vascular disease. Nareg Roubinian, MD, MPH Paul D. Blanc, MD, MSPH, FCCP Hubert Chen, MD, MPH, FCCP San Francisco, CA Affiliations: From the Department of Medicine (Drs Roubinian, Blanc, and Chen), University of California-San Francisco; and Genentech, Inc (Dr Chen). Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Nareg Roubinian, MD, MPH, University of California-San Francisco, Department of Medicine, 533 Parnassus Ave, Room U127, San Francisco, CA 94143; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2898
References 1. Roubinian N, Elliott CG, Barnett CF, et al. Effects of commercial air travel on patients with pulmonary hypertension. Chest. 2012;142(4):885-892. 2. Smith TG, Talbot NP, Chang RW, et al. Pulmonary artery pressure increases during commercial air travel in healthy passengers. Aviat Space Environ Med. 2012;83(7):673-676. 3. Shrikrishna D, Coker RK; Air Travel Working Party of the British Thoracic Society Standards of Care Committee. Managing passengers with stable respiratory disease planning air travel: British Thoracic Society recommendations. Thorax. 2011;66(9):831-833. 4. Smith TG, Chang RW, Robbins PA, Dorrington KL. Commercial air travel and in-flight pulmonary hypertension. Aviat Space Environ Med. 2013;84(1):65-67.
Chest Ultrasonography as a Replacement for Chest Radiography for Community-Acquired Pneumonia To the Editor: The recently published prospective study by Reissig et al1 in CHEST (October 2012) has suggested the use of lung ultrasound (LUS) for diagnosis and follow-up of community-acquired pneumonia. This is an innovative study with achievement of very good specificity and sensitivity by highly trained sonographers. Clearly, there are advantages to the use of LUS over chest radiography CHEST / 143 / 3 / MARCH 2013
877
(CXR), specifically the lack of radiation, which would make this an attractive modality in children, women who are pregnant, and young female patients. In addition, LUS can detect other ancillary findings not always evident on the CXR2 as well as facilitating pleural sampling. What are the caveats? Like its use compared with CT scanning3 and CXR in pneumothorax,4 at the moment, the use of LUS should be seen as complementary to the CXR in communityacquired pneumonia. In smokers or adults . 50 years of age, CXR is recommended at follow-up to detect any underlying proximal disease (eg, lung cancer). How does LUS compare with CXR here? UK national guidelines in adults with communityacquired pneumonia still recommend the use of CXR; LUS is not mentioned once in the document.5 Training of ultrasonographers would require at least level two Royal College of Radiology training in chest ultrasound in the United Kingdom to perform and interpret the LUS.6 In addition, acquisition and interpretation of LUS images is notoriously operator dependent, unlike interpretation of CXR (or CT scan). Finally, the CXR may also give useful ancillary information not available from the LUS (eg, mediastinal adenopathy, pulmonary vascular or cardiac disease, underlying lung disease, or metastatic disease). In summary, LUS looks promising as an adjunctive technique in community-acquired pneumonia by adequately trained sonographers, with a particular role for those patients in whom radiation should be avoided. Otherwise, it should have a complementary role to CXR at the current time, pending further validation. Andrew R. L. Medford, MBChB, MD Bristol, England Affiliations: From the North Bristol Lung Centre, Southmead Hospital. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Andrew R. L. Medford, MBChB, MD, North Bristol Lung Centre, Southmead Hospital, Westbury-onTrym, Bristol, BS10 5NB, England; e-mail: andrewmedford@ hotmail.com © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2653
References 1. Reissig A, Copetti R, Mathis G, et al. Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia. A prospective, multicenter, diagnostic accuracy study. Chest. 2012;142(4):965-972. 2. Medford AR, Entwisle JJ. Indications for thoracic ultrasound in chest medicine: an observational study. Postgrad Med J. 2010;86(1011):8-11. 3. Medford AR, Entwisle JJ. Thoracic ultrasound in malignant pleural effusion: a real world perspective. Thorax. 2009;64(11): 1005. 4. Medford AR. Chest ultrasonography as a replacement for chest radiography in the ED. Chest. 2011;140(5):1386-1387. 5. Lim WS, Baudouin SV, George RC, et al; Pneumonia Guidelines Committee of the BTS Standards of Care Committee. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009;64(suppl 3): iii1-iii55. 6. Royal College of Radiologists. 2005. Ultrasound training recommendations for medical and surgical specialties. Ref No: BFCR (05)2. The Royal College of Radiologists website. http:// www.rcr.ac.uk/publications.aspx.Accessed October 26, 2012. 878
Downloaded From: http://journal.publications.chestnet.org/ on 03/07/2013
Response To the Editor: I thank Dr Medford for his interesting comments on our recent article in CHEST1 on lung ultrasound (LUS) in the diagnosis and follow-up of community-acquired pneumonia (CAP). I agree that the lack of radiation makes LUS an attractive modality in children, women who are pregnant, and young female patients. Furthermore, sonography may help stem the increasing levels of iatrogenic radiation exposure due to the increasing availability and use of CT scanning.2 Although LUS seems to be especially useful in situations in which chest radiography is not available (eg, home visits, emergency situations), not immediately available (eg, ED), or of limited use (eg, in bedridden patients not able to undergo radiographs in two planes), our study,1 as well as that of Parlamento et al,3 has demonstrated that LUS is an excellent diagnostic tool in the evaluation of all patients with suspected CAP. I agree that LUS is operator dependent. Proper training in LUS is essential, just as it is for interpretation of radiographs4 and CT scans. In the United States5 and Germany, ultrasound training is increasingly a part of the education of medical students. With respect to the question of the usefulness of chest radiography for identifying underlying malignancy, I would like to point out that the primary goal of our study was to establish the usefulness of LUS in diagnosing CAP. A study found a low incidence of new lung cancer after pneumonia: approximately 1% within 90 days and 2% over 5 years.6 The authors concluded that routine chest radiographs after pneumonia for detecting lung cancer are not warranted.6 However, the use of radiography may be questionable in light of recent studies showing a low sensitivity of radiography in identifying lung cancer, in comparison with CT scanning.7 In our study, fluid bronchograms, a possible sign of an occult obstructive process such as cancer, were identified in only 17 patients. In only one of these patients, lung carcinoma was diagnosed 3 months later. In another patient whose fluid bronchograms prompted the suspicion of lung carcinoma, no cancer was identified despite an extensive workup, including CT scanning and bronchoscopy. In a third patient, the incidental finding of liver metastases during LUS performed for suspected CAP diagnosed occult cancer that had not been identified by chest radiograph, resulting in immediate modification of the patient’s management. However, in all cases with incomplete or delayed recovery from CAP, persistent symptoms, especially in patients with evidence of fluid bronchogram and/or risk factors for lung cancer, further diagnostic procedures are indicated, especially CT scanning. Therefore, as we mentioned in our conclusions, a chest radiograph or CT scan is necessary in cases with a negative ultrasound, if other differential diagnoses are taken into account or if complications occur.1 Angelika Reissig, MD Jena, Germany Affiliations: From Pneumology and Allergology, Clinic for Internal Medicine I, University Hospital Jena, Friedrich-Schiller-University. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Angelika Reissig, MD, Pneumology and Allergology, Clinic for Internal Medicine I, University Hospital Jena, Friedrich-Schiller-University, Erlanger Allee 101, D-07740 Jena, Germany; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2780 Correspondence
References 1. Roubinian N, Elliott CG, Barnett CF, et al. Effects of commercial air travel on patients with pulmonary hypertension. Chest. 2012;142(4):885-892. 2. Smith TG, Talbot NP, Chang RW, et al. Pulmonary artery pressure increases during commercial air travel in healthy passengers. Aviat Space Environ Med. 2012;83(7):673-676. 3. Smith TG, Chang RW, Robbins PA, Dorrington KL. Commercial air travel and in-flight pulmonary hypertension. Aviat Space Environ Med. 2013;84(1):65-67.
Response To the Editor: We thank Dr Smith for his thoughtful comments regarding our recent publication in CHEST (October 2012).1 We took great interest in his recently published findings demonstrating an increase in estimated pulmonary artery pressures in healthy air passengers without hypoxemia.2 In our study, we used an a priori-defined oxygen desaturation value of pulse oxygen saturation (Spo2) , 85% (corresponding to partial pressure of oxygen in the blood of approximately 50 mm Hg at sea level). We chose this value to maintain a high specificity for oxygen desaturation events, consistent with this being the recommended threshold for prescribing in-flight supplemental oxygen in individuals, based on altitude simulation testing.3 We agree that a more sensitive threshold for oxygen desaturation may correlate better with flight symptoms and/or pulmonary vasoconstriction events. Using our original threshold of Spo2 , 85%, we did not find a significant association between desaturation events and flight symptoms (P 5 .25). However, we did find that the oxygen saturation nadir was lower in individuals with flight symptoms compared with those without symptoms (Spo2, 85% vs 89%; P 5 .03). Notably, even when using this more restrictive cutoff for Spo2 of 85%, there were four subjects who remained asymptomatic despite desaturation events. Using a more sensitive threshold of oxygen desaturation (Spo2 , 88%), we found a significant association with flight sympjournal.publications.chestnet.org
Downloaded From: http://journal.publications.chestnet.org/ on 03/07/2013
toms (P , .01) and a similar number of individuals with asymptomatic oxygen desaturation. When the threshold was further increased (Spo2 , 90%), we saw an even stronger association with flight symptoms, but there was also a substantial increase in the number of individuals with asymptomatic oxygen desaturation by this definition. Therefore, a cutpoint of Spo2 , 88% appeared to have the best performance characteristics with respect to reported symptoms. Dr Smith’s findings, taken together with our study results, imply that even under mildly hypoxic conditions, individuals with underlying pulmonary vascular disease may experience symptoms as a result of elevations in pulmonary artery pressure.1,4 Further studies are needed to better understand the relationship between changes in pulmonary artery pressures, symptoms, and desaturation events during flight, and their implications with regard to air travel safety for patients with pulmonary vascular disease. Nareg Roubinian, MD, MPH Paul D. Blanc, MD, MSPH, FCCP Hubert Chen, MD, MPH, FCCP San Francisco, CA Affiliations: From the Department of Medicine (Drs Roubinian, Blanc, and Chen), University of California-San Francisco; and Genentech, Inc (Dr Chen). Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Nareg Roubinian, MD, MPH, University of California-San Francisco, Department of Medicine, 533 Parnassus Ave, Room U127, San Francisco, CA 94143; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2898
References 1. Roubinian N, Elliott CG, Barnett CF, et al. Effects of commercial air travel on patients with pulmonary hypertension. Chest. 2012;142(4):885-892. 2. Smith TG, Talbot NP, Chang RW, et al. Pulmonary artery pressure increases during commercial air travel in healthy passengers. Aviat Space Environ Med. 2012;83(7):673-676. 3. Shrikrishna D, Coker RK; Air Travel Working Party of the British Thoracic Society Standards of Care Committee. Managing passengers with stable respiratory disease planning air travel: British Thoracic Society recommendations. Thorax. 2011;66(9):831-833. 4. Smith TG, Chang RW, Robbins PA, Dorrington KL. Commercial air travel and in-flight pulmonary hypertension. Aviat Space Environ Med. 2013;84(1):65-67.
Chest Ultrasonography as a Replacement for Chest Radiography for Community-Acquired Pneumonia To the Editor: The recently published prospective study by Reissig et al1 in CHEST (October 2012) has suggested the use of lung ultrasound (LUS) for diagnosis and follow-up of community-acquired pneumonia. This is an innovative study with achievement of very good specificity and sensitivity by highly trained sonographers. Clearly, there are advantages to the use of LUS over chest radiography CHEST / 143 / 3 / MARCH 2013
877
(CXR), specifically the lack of radiation, which would make this an attractive modality in children, women who are pregnant, and young female patients. In addition, LUS can detect other ancillary findings not always evident on the CXR2 as well as facilitating pleural sampling. What are the caveats? Like its use compared with CT scanning3 and CXR in pneumothorax,4 at the moment, the use of LUS should be seen as complementary to the CXR in communityacquired pneumonia. In smokers or adults . 50 years of age, CXR is recommended at follow-up to detect any underlying proximal disease (eg, lung cancer). How does LUS compare with CXR here? UK national guidelines in adults with communityacquired pneumonia still recommend the use of CXR; LUS is not mentioned once in the document.5 Training of ultrasonographers would require at least level two Royal College of Radiology training in chest ultrasound in the United Kingdom to perform and interpret the LUS.6 In addition, acquisition and interpretation of LUS images is notoriously operator dependent, unlike interpretation of CXR (or CT scan). Finally, the CXR may also give useful ancillary information not available from the LUS (eg, mediastinal adenopathy, pulmonary vascular or cardiac disease, underlying lung disease, or metastatic disease). In summary, LUS looks promising as an adjunctive technique in community-acquired pneumonia by adequately trained sonographers, with a particular role for those patients in whom radiation should be avoided. Otherwise, it should have a complementary role to CXR at the current time, pending further validation. Andrew R. L. Medford, MBChB, MD Bristol, England Affiliations: From the North Bristol Lung Centre, Southmead Hospital. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Andrew R. L. Medford, MBChB, MD, North Bristol Lung Centre, Southmead Hospital, Westbury-onTrym, Bristol, BS10 5NB, England; e-mail: andrewmedford@ hotmail.com © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2653
References 1. Reissig A, Copetti R, Mathis G, et al. Lung ultrasound in the diagnosis and follow-up of community-acquired pneumonia. A prospective, multicenter, diagnostic accuracy study. Chest. 2012;142(4):965-972. 2. Medford AR, Entwisle JJ. Indications for thoracic ultrasound in chest medicine: an observational study. Postgrad Med J. 2010;86(1011):8-11. 3. Medford AR, Entwisle JJ. Thoracic ultrasound in malignant pleural effusion: a real world perspective. Thorax. 2009;64(11): 1005. 4. Medford AR. Chest ultrasonography as a replacement for chest radiography in the ED. Chest. 2011;140(5):1386-1387. 5. Lim WS, Baudouin SV, George RC, et al; Pneumonia Guidelines Committee of the BTS Standards of Care Committee. BTS guidelines for the management of community acquired pneumonia in adults: update 2009. Thorax. 2009;64(suppl 3): iii1-iii55. 6. Royal College of Radiologists. 2005. Ultrasound training recommendations for medical and surgical specialties. Ref No: BFCR (05)2. The Royal College of Radiologists website. http:// www.rcr.ac.uk/publications.aspx.Accessed October 26, 2012. 878
Downloaded From: http://journal.publications.chestnet.org/ on 03/07/2013
Response To the Editor: I thank Dr Medford for his interesting comments on our recent article in CHEST1 on lung ultrasound (LUS) in the diagnosis and follow-up of community-acquired pneumonia (CAP). I agree that the lack of radiation makes LUS an attractive modality in children, women who are pregnant, and young female patients. Furthermore, sonography may help stem the increasing levels of iatrogenic radiation exposure due to the increasing availability and use of CT scanning.2 Although LUS seems to be especially useful in situations in which chest radiography is not available (eg, home visits, emergency situations), not immediately available (eg, ED), or of limited use (eg, in bedridden patients not able to undergo radiographs in two planes), our study,1 as well as that of Parlamento et al,3 has demonstrated that LUS is an excellent diagnostic tool in the evaluation of all patients with suspected CAP. I agree that LUS is operator dependent. Proper training in LUS is essential, just as it is for interpretation of radiographs4 and CT scans. In the United States5 and Germany, ultrasound training is increasingly a part of the education of medical students. With respect to the question of the usefulness of chest radiography for identifying underlying malignancy, I would like to point out that the primary goal of our study was to establish the usefulness of LUS in diagnosing CAP. A study found a low incidence of new lung cancer after pneumonia: approximately 1% within 90 days and 2% over 5 years.6 The authors concluded that routine chest radiographs after pneumonia for detecting lung cancer are not warranted.6 However, the use of radiography may be questionable in light of recent studies showing a low sensitivity of radiography in identifying lung cancer, in comparison with CT scanning.7 In our study, fluid bronchograms, a possible sign of an occult obstructive process such as cancer, were identified in only 17 patients. In only one of these patients, lung carcinoma was diagnosed 3 months later. In another patient whose fluid bronchograms prompted the suspicion of lung carcinoma, no cancer was identified despite an extensive workup, including CT scanning and bronchoscopy. In a third patient, the incidental finding of liver metastases during LUS performed for suspected CAP diagnosed occult cancer that had not been identified by chest radiograph, resulting in immediate modification of the patient’s management. However, in all cases with incomplete or delayed recovery from CAP, persistent symptoms, especially in patients with evidence of fluid bronchogram and/or risk factors for lung cancer, further diagnostic procedures are indicated, especially CT scanning. Therefore, as we mentioned in our conclusions, a chest radiograph or CT scan is necessary in cases with a negative ultrasound, if other differential diagnoses are taken into account or if complications occur.1 Angelika Reissig, MD Jena, Germany Affiliations: From Pneumology and Allergology, Clinic for Internal Medicine I, University Hospital Jena, Friedrich-Schiller-University. Financial/nonfinancial disclosures: The author has reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article. Correspondence to: Angelika Reissig, MD, Pneumology and Allergology, Clinic for Internal Medicine I, University Hospital Jena, Friedrich-Schiller-University, Erlanger Allee 101, D-07740 Jena, Germany; e-mail: [email protected] © 2013 American College of Chest Physicians. Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details. DOI: 10.1378/chest.12-2780 Correspondence