We present the case of a 45-year-old female who presented multiple times to the emergency department with acute low back pain and was subsequently diagnosed with bilateral psoas muscle abscess. Psoas abscess is an uncommon cause of acute low back pain that is associated with high morbidity and mortality. The onset of symptoms is frequently insidious and the clinical presentation vague. Proper diagnosis requires vigilance of the physician to recognize signs in the history and physical examination that are suggestive of a potentially serious spinal condition and initiate further workup. While most patients with acute low back pain have a benign etiology, this case report demonstrates the challenge of diagnosing a patient with bilateral psoas abscess who had few known risk factors and symptoms typical of mechanical low back pain.

[West J Emerg Med. 2009;10(4):288-291.]

Introduction: The Masimo Radical-7 Pulse CO-Oximeter is a medical device recently approved by the US Food and Drug Administration that performs noninvasive oximetry and estimated venous or arterial hemoglobin measurements. A portable, noninvasive device that rapidly measures hemoglobin concentration could be useful in both austere and modern hospital settings. The objective of this study is to determine the degree of variation between the device’s estimated hemoglobin measurement and the actual venous hemoglobin concentration in undifferentiated emergency department (ED) patients.

Methods: We conducted a prospective, observational, cross-sectional study of adult patients presenting to the ED. The subjects consisted of a convenience sample of adult ED patients who required a complete blood count as part of their care in the ED. A simultaneous probe hemoglobin was obtained and recorded.

Results: Bias between probe and laboratory hemoglobin measurements was _0.5 (95% confidence interval,_0.8 to_0.1) but this was not statistically significant from 0 (t 0.05,124¼0.20, P . 0.5). The limits of agreement were _4.7 and 3.8, beyond the clinically relevant standard of equivalency of 6 1 g/dL.

Conclusion: These data suggest that noninvasive hemoglobin determination is not sufficiently accurate for emergency department use. [West J Emerg Med. 2013;14(3):283–286.]