ATS SEMINARS Introduction to ATS Seminars: Intensive Care Ultrasound Few innovations have changed critical care as dramatically as pointof-care ultrasound. A decade ago, most intensivists used ultrasound solely for central venous catheter insertion, although some early adopters, mostly in Europe, recognized its broader potential. As devices became commonplace in the ICU, and as image quality improved, ultrasound proved to be highly useful for revealing fluid collections, interrogating the lungs, judging cardiac function and the nature of shock, seeking sources of sepsis, assessing the trauma victim, and many other uses. As important, placing the ultrasound transducer in the intensivist’s hand brought to light obvious advantages: immediacy, repeatability, and integration. Rather than waiting for an imaging specialist to send a technician, interpret the images, and produce a report, the ultrasound-capable intensivist personally performs, interprets, and integrates immediately the findings into the broader clinical assessment and plan. Moreover, when the ultrasound examination suggests a clinical hypothesis (say, that infusion of dobutamine will produce a meaningful improvement in severe systolic left ventricular dysfunction), the study can simply be repeated in 30 minutes to confirm or refute that hypothesis. Of course, ultrasound is not a panacea: quality images rely on skill, persistence, and luck, especially in those with obesity, anasarca, drains, wounds, and barriers to ideal positioning. The rapid pace of change has caught many intensivists off guard. Intensive care ultrasound demands learning to acquire and interpret images, and to recognize its limitations. Most clinicians did not learn critical care ultrasound during training and find it hard to carve out sufficient time to develop skills or find competent mentorship. Even now, fellowships are highly uneven in devoting educational resources to ultrasound and nurturing a critical mass of ultrasound-trained faculty. Only recently have standards for training and competence in intensive care ultrasound been published. Finally, in some hospitals logistical or political challenges may pose additional hurdles. To assist the aspiring intensivist, AnnalsATS introduces a Seminar in ICU Ultrasound. Consisting of six planned articles to be published in sets of two, the series describes the most common applications of intensivist-conducted ultrasonography and, as befits a visual diagnostic tool, is richly illustrated with figures and video files (on the ATS website at www.atsjournals.org). For intensivists using ultrasound regularly, these articles serve to describe the foundation supporting this blossoming field while using prototypical images to illuminate techniques and findings. For the novice seeking an introduction, we hope to show that mastery of ICU ultrasound cannot only improve patient care, but heighten the clinician’s appreciation for the pathophysiology of critical illness. Indeed, we are convinced that competence in critical care ultrasound is essential to clinical practice. The series begins this month with two articles, the first titled “I. Physics, Equipment, and Image Quality,” which explores the background underlying ultrasound imaging, including the tradeoffs of image depth and resolution. Also covered in broad strokes are the various ultrasound techniques available to the intensivist, including two-dimensional and M-mode imaging, 538
along with color, continuous wave, and pulse wave Doppler methods. Image artifacts that can confuse or frustrate the clinician are explained. In addition, this article should prove useful for those seeking to purchase ultrasound devices for ICU application. The second article included in this month’s issue is “II. Central Vascular Access and Venous Diagnostic Ultrasound.” The many advantages of ultrasound-guided central venous access (firstpass success, ultimate success, complications) have made older “anatomic” approaches obsolete, especially at the jugular and femoral sites. Thus, most intensivists are both comfortable and experienced in using ultrasound for this purpose. Nevertheless, all who insert central lines can learn something new from this article, especially by broadening their procedural repertoire or learning new ways to make a safe procedure even safer. Finally, this article reviews the anatomy and technique needed to diagnose or exclude deep venous thrombosis. The well-trained intensivist can not only perform these studies accurately but, in most ICUs, also more expeditiously than a consultant radiologist or vascular surgeon. Future articles will survey the wider use of intensive care ultrasound. Next is “III. Lung and Pleural Ultrasound,” describing how lung artifacts can be interpreted to reveal the nature and severity of lung conditions such as pulmonary edema and pneumonia, or to document the impact of ultrafiltration or PEEPinduced recruitment. Pleural diseases benefit, too, from ultrasound assessment. This is widely accepted for localizing and draining pleural fluid collections, but it is increasingly apparent that ultrasound holds real advantages over radiography for detecting and treating pneumothorax. Finally, ultrasound is the preferred method for judging diaphragm dysfunction. Fourth in the series is “IV. Abdominal and Retroperitoneal Ultrasound,” showing the role of ultrasound for hepato-biliary, renal, and splenic lesions, and for the assessment of ascites and blood, especially in the setting of trauma. Intensive care echocardiography can be divided into “goaldirected” (identify the cause for shock, severe left ventricular dysfunction, pericardial effusion, and major valve lesions) and “advanced” approaches (fluid and tissue Doppler, assess segmental wall motion, acquire additional views, measure pressure gradients, and identify diastolic dysfunction, for example). The fifth article in the series, “V. Goal-directed Echocardiography,” will address a skill that all intensivists should seek to attain. This article will not delve into advanced echocardiography nor the transesophageal approach; rather, the emphasis is on a set of standard images useful for guiding care of the patient in shock. Fortunately, adequate transthoracic images to conduct goal-oriented echocardiography can be obtained in nearly 90 percent of such patients. The final article, “VI. Assessing Shock and Predicting FluidResponsiveness,” will seek to link goal-directed echocardiography to the clinical assessment of shock. In addition, ultrasound’s role in predicting fluid-responsiveness by elucidating the interactions between respiration and the circulation will be examined in detail. Two additional effects of intensive care ultrasonography may contribute to its rise. First, ultrasonography opens a window onto pathophysiology, illuminating the way the pleura glides, or a vein collapses with inspiration, or how completely a cardiac valve slams shut. The demise of the pulmonary artery catheter left intensivists with one tool fewer to examine fundamentally important circulatory AnnalsATS Volume 10 Number 5 | October 2013
ATS SEMINARS parameters; ultrasound brings this back, and then some. Second, in an era dominated by technology, bedside ultrasound creates a rare moment of intimacy as the doctor lays on hands. All together, these attributes make ultrasound an essential part of modern critical care. Author disclosures are available with the text of this article at www.atsjournals.org.
ATS Seminars
Gregory A. Schmidt, M.D. Department of Internal Medicine University of Iowa Iowa City, Iowa Dean Schraufnagel, M.D. Department of Medicine University of Illinois at Chicago Chicago, Illinois Copyright © 2013 by the American Thoracic Society
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along with color, continuous wave, and pulse wave Doppler methods. Image artifacts that can confuse or frustrate the clinician are explained. In addition, this article should prove useful for those seeking to purchase ultrasound devices for ICU application. The second article included in this month’s issue is “II. Central Vascular Access and Venous Diagnostic Ultrasound.” The many advantages of ultrasound-guided central venous access (firstpass success, ultimate success, complications) have made older “anatomic” approaches obsolete, especially at the jugular and femoral sites. Thus, most intensivists are both comfortable and experienced in using ultrasound for this purpose. Nevertheless, all who insert central lines can learn something new from this article, especially by broadening their procedural repertoire or learning new ways to make a safe procedure even safer. Finally, this article reviews the anatomy and technique needed to diagnose or exclude deep venous thrombosis. The well-trained intensivist can not only perform these studies accurately but, in most ICUs, also more expeditiously than a consultant radiologist or vascular surgeon. Future articles will survey the wider use of intensive care ultrasound. Next is “III. Lung and Pleural Ultrasound,” describing how lung artifacts can be interpreted to reveal the nature and severity of lung conditions such as pulmonary edema and pneumonia, or to document the impact of ultrafiltration or PEEPinduced recruitment. Pleural diseases benefit, too, from ultrasound assessment. This is widely accepted for localizing and draining pleural fluid collections, but it is increasingly apparent that ultrasound holds real advantages over radiography for detecting and treating pneumothorax. Finally, ultrasound is the preferred method for judging diaphragm dysfunction. Fourth in the series is “IV. Abdominal and Retroperitoneal Ultrasound,” showing the role of ultrasound for hepato-biliary, renal, and splenic lesions, and for the assessment of ascites and blood, especially in the setting of trauma. Intensive care echocardiography can be divided into “goaldirected” (identify the cause for shock, severe left ventricular dysfunction, pericardial effusion, and major valve lesions) and “advanced” approaches (fluid and tissue Doppler, assess segmental wall motion, acquire additional views, measure pressure gradients, and identify diastolic dysfunction, for example). The fifth article in the series, “V. Goal-directed Echocardiography,” will address a skill that all intensivists should seek to attain. This article will not delve into advanced echocardiography nor the transesophageal approach; rather, the emphasis is on a set of standard images useful for guiding care of the patient in shock. Fortunately, adequate transthoracic images to conduct goal-oriented echocardiography can be obtained in nearly 90 percent of such patients. The final article, “VI. Assessing Shock and Predicting FluidResponsiveness,” will seek to link goal-directed echocardiography to the clinical assessment of shock. In addition, ultrasound’s role in predicting fluid-responsiveness by elucidating the interactions between respiration and the circulation will be examined in detail. Two additional effects of intensive care ultrasonography may contribute to its rise. First, ultrasonography opens a window onto pathophysiology, illuminating the way the pleura glides, or a vein collapses with inspiration, or how completely a cardiac valve slams shut. The demise of the pulmonary artery catheter left intensivists with one tool fewer to examine fundamentally important circulatory AnnalsATS Volume 10 Number 5 | October 2013
ATS SEMINARS parameters; ultrasound brings this back, and then some. Second, in an era dominated by technology, bedside ultrasound creates a rare moment of intimacy as the doctor lays on hands. All together, these attributes make ultrasound an essential part of modern critical care. Author disclosures are available with the text of this article at www.atsjournals.org.
ATS Seminars
Gregory A. Schmidt, M.D. Department of Internal Medicine University of Iowa Iowa City, Iowa Dean Schraufnagel, M.D. Department of Medicine University of Illinois at Chicago Chicago, Illinois Copyright © 2013 by the American Thoracic Society
539
