Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues	$ 1,840	$ 1,809
Cost of revenues	1,467	1,415
Gross profit	373	394
Operating expenses:
Research and development	1,414	1,777
Selling, general and administrative	3,986	4,500
Total operating expenses	5,400	6,277
Loss from operations	(5,027)	(5,883)
Interest income	82	33
Interest expense	(350)	(4,672)
Other income, net	240	241
Net loss and comprehensive loss	(5,055)	(10,281)
Accretion of preferred stock dividends	(895)	(410)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock		(5,216)
Net loss applicable to common stockholders	$ (5,950)	$ (15,907)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.14)	$ (7.99)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	42,481	1,992