The Article: Shokoohi et al. “Bedside Ultrasound Reduces Diagnostic Uncertainty and Guides Resuscitation in Patients With Undifferentiated Hypotension” Critical Care Medicine 2015 Dec; 43(12):2562-2569
The Idea: Undifferentiated hypotension and shock are critical conditions in which time is of the essence for management; however, determining causes with only history and physical examination can be difficult and diagnostic uncertainty can lead to neglecting important parts of the clinical picture or delay definitive management. This article investigates the effectiveness of bedside ultrasound in evaluating the patient with undifferentiated hypotension and its utility in determining directions of management including pharmacologically, fluid/blood resuscitation, further diagnostic imaging and change in disposition.
The Study: This was a single center prospective observational study taking place in the emergency department of an academic tertiary care hospital.
Inclusion Criteria: 18+ years of age, systolic blood pressure of <90 mmHg after at least 1L of normal saline, AND lacking a obvious source of hypotension.
Exclusion Criteria: Patients with obvious source of hypotension (e.g. hemorrhage or MI), or trauma related hypotension, or patients with a Do Not Resuscitate order in whom the treating physician did not intend to use comprehensive resuscitation.
Physicians filled out a questionnaire evaluating their certainty of diagnosis and treatment plans prior to ultrasound and completed a post-ultrasound portion following receiving results (obtained by different ultrasound-experienced physicians). Ultrasound protocol included typical components of bedside echocardiogram including IVC measurements, FAST, aorta scans, and thoracic scanning for evaluation of effusion and pneumothorax. Chart review was completed by consensus of 2 intensivists to determine final diagnoses. Diagnostic certainty was evaluated according to the Shannon Information theory that is based on a “binary entropy function” where certainty is evaluated according to its closeness to either 0% or 100%.
Primary Endpoints: Change in treating physician’s diagnostic certainty and concordance between post-ultrasound diagnosis and final diagnosis following chart review.
Secondary Endpoints: Post-ultrasound change in treatment plans, use of diagnostic imaging, and disposition.
The Results: 118 patients with a mean age of 62 years were included in the study. There was a decrease in patient complexity and diagnostic uncertainty following the bedside ultrasound and a significant increase in definitive diagnoses. In 25% of the patients, they found a change in treatment plan. Plan for further imaging changed in 36 with number of CT scans increasing from 48 to 51. 25% of patients had a change in type of CT scan ordered (chest to abdominopelvic or vice versa). 16 patients had a change in plan for consultation, and 14 had a change in level of admission. An interesting inclusion in this article is the images from four cases where the diagnosis following ultrasound was not only drastically different from the initial suspicion, but also very time sensitive. The leading diagnosis following the ultrasound protocol was the same as the final discharge diagnosis 86% of the time, and ultrasound findings matched the inpatient CT findings in the discrepant cases.
The Takeaway: Despite the limitations of the study (relatively small, relatively unknown statistical analysis via binary entropy function, and lack of focus on patient outcomes), this article demonstrated that early utilization of ultrasound in patients with undifferentiated hypotension is an effective method to arrive at an early actionable diagnosis. Findings can significantly affect treatment plans and use of other imaging modalities. In summary, ultrasound plays a critical role in the diagnosis and management of patients with undifferentiated hypotension, and protocols implementing its use would likely improve outcomes.
Author: Connor Mooney, MS4