My patient has no blood pressure: are they empty or full? Point-of-care ultrasound of the inferior vena cava in the hypotensive emergency department patient

Bedside, focused or point-of-care ultrasound (PoCUS) is becoming an established technique within emergency and critical care medicine to answer time-dependent, focused clinical questions. Bedside sonography is not a complete radiological investigation, rather an extension of the clinical examination to rule in or rule out key diagnoses in specific clinical settings. PoCUS is geared to addressing highly time-dependent and focused questions, and in general most focused scans become more obviously positive as the patient becomes increasingly unwell. In the hypotensive patient, one of the first questions a clinician must address is whether the patient requires emergency fluid resuscitation. That is, is the patient under-filled or overloaded? So, how can we use ultrasound to add value to our clinical assessment of filling in the hypotensive patient?