Bedside Ultrasound Reduces Diagnostic Uncertainty and Guides Resuscitation in Patients With Undifferentiated Hypotension*

OBJECTIVES: Utilization of ultrasound in the evaluation of patients with undifferentiated hypotension has been proposed in several protocols. We sought to assess the impact of an ultrasound hypotension protocol on physicians' diagnostic certainty, diagnostic ability, and treatment and resource utilization. DESIGN: Prospective observational study. SETTING: Emergency department in a single, academic tertiary care hospital. SUBJECTS: A convenience sample of patients with a systolic blood pressure less than 90 mm Hg after an initial fluid resuscitation, who lacked an obvious source of hypotension. INTERVENTIONS: An ultrasound-trained physician performed an ultrasound on each patient using a standardized hypotension protocol. Differential diagnosis and management plan was solicited from the treating physician immediately before and after the ultrasound. Blinded chart review was conducted for management and diagnosis during the emergency department and inpatient hospital stay. MEASUREMENTS AND MAIN RESULTS: The primary endpoints were the identification of an accurate cause for hypotension and change in physicians' diagnostic uncertainty. The secondary endpoints were changes in treatment plan, use of resources, and changes in disposition after performing the ultrasound. One hundred eighteen patients with a mean age of 62 years were enrolled. There was a significant 27.7% decrease in the mean aggregate complexity of diagnostic uncertainty before and after the ultrasound hypotension protocol (1.85-1.34; -0.51 95% CI, -0.41 to -0.62) as well as a significant increase in the absolute proportion of patients with a definitive diagnosis from 0.8% to 12.7%. Overall, the leading diagnosis after the ultrasound hypotension protocol demonstrated excellent concordance with the blinded consensus final diagnosis (Cohen k = 0.80). Twenty-nine patients (24.6%) had a significant change in the use of IV fluids, vasoactive agents, or blood products. There were also significant changes in major diagnostic imaging (30.5%), consultation (13.6%), and emergency department disposition (11.9%). CONCLUSIONS: Clinical management involving the early use of ultrasound in patients with hypotension accurately guides diagnosis, significantly reduces physicians' diagnostic uncertainty, and substantially changes management and resource utilization in the emergency department.