By Kathryn Radigan, MD
Attending Physician, Division of Pulmonary and Critical Care, Stroger Hospital of Cook County, Chicago; Assistant Professor of Medicine; Rush University Medical College
Dr. Radigan reports no financial relationships relevant to this field of study.
SYNOPSIS: The use of bedside ultrasound for patients with undifferentiated hypotension in the emergency department substantially changed the plan of care and reduced physician diagnostic uncertainty.
SOURCE: Shokoohi H, et al. Bedside ultrasound reduces diagnostic uncertainty and guides resuscitation in patients with undifferentiated hypotension. Crit Care Med 2015;43:2562-2569.
The use of bedside ultrasound has expanded tremendously over the last few decades. As it is readily available and relatively inexpensive, ultrasound provides the opportunity to examine hypotensive, critically ill patients, potentially leading to a faster, more accurate diagnosis.
Shokoohi et al used bedside ultrasound in an emergency department (ED) to help determine the etiology of undifferentiated hypotension. In this prospective, observational trial conducted at a single, academic, tertiary care hospital within a 32-month period, 118 patients with a systolic blood pressure < 90 mmHg after initial fluid resuscitation without an obvious source of hypotension were examined with an ultrasound using a standardized hypotension protocol. Although the duration of ultrasound exam was not recorded, a formally trained attending physician with extensive experience in emergency and critical care ultrasound performed the ultrasound protocol and included a focused cardiac scan to assess cardiac contractility, right ventricle size, and the presence of pericardial effusion/tamponade. It also included an inferior vena cava, abdominal, and transthoracic scan. Primary outcome measures included change in treating physician’s diagnostic certainty before and after ultrasound and concordance of post-ultrasound ED diagnosis with chart review final diagnosis. Secondary outcomes were changes in treatment plan, use of resources, and changes in disposition after performing ultrasound protocol.
Results of the study revealed a 28% decrease in mean aggregate complexity of diagnostic uncertainty before and after ultrasound protocol (1.85-1.34; -0.51; 95% confidence interval, -0.41 to -0.62) along with a significant increase in the proportion of patients with a definitive diagnosis from 0.8% to 12.7%. There was exceptional concordance with the blinded consensus final diagnosis (Cohen kappa = 0.80). Furthermore, 24.6% of patients experienced a significant change in the use of IV fluids, vasoactive agents, and blood products, and there were significant changes in plans for further diagnostic imaging (30.5%) and ED disposition (11.9%). Early use of bedside ultrasound for critically ill patients with undifferentiated hypotension had a clinically significant effect on physicians’ differential diagnosis with subsequent changes in patients’ ED management.
COMMENTARY
Performance of bedside ultrasound has become an invaluable tool for immediate assessment of the critically ill patient, especially for evaluation of goal-directed therapy in the setting of a hemodynamically unstable patient. Shokoohi et al were able to show that early use of bedside ultrasound by a formally trained, experienced attending physician resulted in a statistically significant reduction in physicians’ diagnostic uncertainty, with the leading diagnoses after ultrasound highly concordant with the final diagnosis. It also guided management decisions with significant changes in resuscitation efforts, diagnostic imaging, and ED disposition. Additionally, echo in the critically ill patient is known to be portable, quick, easy to use, and cost-effective.1 It can also be used serially in patients to assess response to interventions in “real-time.”
Proper training is the main challenge of utilizing ultrasound for the diagnostic assessment and treatment of the ICU patient. The recent International consensus statement on training standards for advanced critical care echocardiography states that training programs should be rigorous and include competence-based testing.2 The American College of Emergency Physicians suggests that didactic training, extensive hands-on experience, and expert review, along with formal certification, be included in every case.3 This is particularly important, as proper training for intensivists requires competence in patients who are the most technically difficult in the most challenging situations. Unfortunately, this particular study did not address proper training, as the ultrasonographers were only described as formally trained attending physicians with “extensive experience” in emergency and critical care ultrasound but without specific reference to the methods of training and/or certification. Fortunately, other recent studies have suggested that training internists and residents with minimal ultrasound skills is feasible and effective.1,4 Regardless of whether the ultrasonographer is a new resident early in training or a well-seasoned attending, it is most critical for the physician to appreciate when necessary images are not acquired or are insufficient for diagnosis. At that point, the timely acquisition of a formal, comprehensive, confirmatory 2-D echocardiogram is essential, which was only performed in a limited number of patients in this study.
It is also important to highlight that the ultrasonographers within this study were blinded to patient’s history and physical exam. It makes one consider the limitations of a trial that would randomize patients to standard care vs bedside echocardiography while blinded to details related to the clinical presentation. However, while these ultrasonographers were blinded to the clinical presentation, there was still a statistically significant change in diagnostic certainty, thus supporting application of ultrasound assessment despite the operator. In our practice, it is important to interpret information in the context of the available clinical presentation with the available hemodynamic information and respiratory data (i.e., central venous pressure, response to fluids, urine output, chest X-ray, venous oxygenation, etc.).
The role of bedside ultrasound in critically ill patients is extremely valuable and continually evolving. As this manuscript supports, bedside ultrasound has become a beneficial modality in the treatment, care, and monitoring of critically ill patients. Establishing optimal bedside echo protocols with the assurance of exceptional training and maintenance of skills remains a critical concern. We should continue to develop high quality and accuracy for echocardiography skills while applying this information to the clinical context of the patient to achieve the optimal benefit for each individual.
REFERENCES
- Razi R, et al. Bedside hand-carried ultrasound by internal medicine residents versus traditional clinical assessment for the identification of systolic dysfunction in patients admitted with decompensated heart failure. J Am Soc Echocardiogr 2011;24:1319-1324.
- Expert Round Table on Echocardiography in ICU. International consensus statement on training standards for advanced critical care echocardiography. Intensive Care Med 2014;40:654-666.
- Labovitz AJ, et al. Focused cardiac ultrasound in the emergent setting: A consensus statement of the American Society of Echocardiography and American College of Emergency Physicians. J Am Soc Echocardiogr 2010;23:1225-1230.
- Vignon P, et al. Focused training for goal-oriented hand-held echocardiography performed by noncardiologist residents in the intensive care unit. Intensive Care Med 2007;33:1795-1799.
