Shareholder's Equity	12 Months Ended
Dec. 31, 2019
Shareholder's Equity [Abstract]
Shareholder's Equity	Note 5—Shareholders’ Equity Series F Convertible Preferred Stock: On November 27, 2017, the Company closed on an underwritten public offering Series F Convertible Preferred Stock and warrants to purchase shares of common stock for gross proceeds of $18.0 million. Net proceeds totaled approximately $16.2 million after deducting the underwriting discounts and commissions and other costs associated with the offering. The offering was comprised of Series F convertible preferred stock, convertible into shares of the Company’s common stock at an initial conversion price of $63.00 per share. Each share of Series F preferred stock was accompanied by a Series 1 warrant, which was to expire on the first anniversary of its issuance, to purchase 16 shares of the Company’s common stock at an exercise price of $63.00 per share, and a Series 2 warrant, which expires on the seventh anniversary of its issuance, to purchase 16 shares of the Company’s common stock at an exercise price of $63.00 per share. The Series F preferred stock has full ratchet price based anti-dilution protection, subject to customary carve outs, in the event of a down-round financing at a price per share below the conversion price of the Series F preferred stock (which protection will expire if, during any 20 of 30 consecutive trading days, the volume weighted average price of the Company’s common stock exceeds 300% of the then-effective conversion price of the Series F preferred stock and the daily dollar trading volume for each trading day during such period exceeds $200,000). The exercise price of the warrants is fixed and does not contain any variable pricing features, nor any price based anti-dilutive features, apart from customary adjustments for stock splits, combinations, reclassifications, stock dividends or fundamental transactions. A total of 18,000 shares of Series F Convertible Preferred Stock initially convertible into 286,714 shares of common stock and warrants to purchase 573,310 shares of common stock were issued in the offering. As noted below, effective July 3, 2018, the conversion price of the Series F convertible preferred stock was reduced from $63.00 to $29.68, the per share price in the July 2018 Offering described below. Effective March 12, 2019, the conversion price of the Series F convertible preferred stock was reduced from $29.68 to $5.25, the per share price to the public of the Series G convertible preferred stock which closed in an underwritten public offering on March 12, 2019. Effective October 25, 2019, the conversion price of the Series F convertible preferred stock was reduced from $5.25 to $1.41, and on November 6, 2019 from $1.41 to $0.9942, the per share price to the public in the October and November 2019 transactions, respectively, described below. As of December 31, 2019, and 2018, 535 shares of the Series F convertible preferred stock remained outstanding. July 2018 Offering: On July 3, 2018, the Company closed on an underwritten public offering of 181,941 shares of its common stock at a public offering price of $29.68 per share, for gross proceeds of $5.4 million, including the full exercise of the underwriters’ over-allotment option to purchase additional shares of the Company’s common stock (the “July 2018 Offering”). Net proceeds totaled approximately $4.6 million after deducting underwriting discounts and commissions and offering expenses. In connection with the July 2018 Offering, and to induce certain institutional investors who hold warrants issued by the Company in November 2017 (“November 2017 Warrants”) to participate in the July 2018 Offering, the Company entered into letter agreements with such institutional investors. Pursuant to the terms of these agreements, the Company agreed, effective July 3, 2018, to reduce the per share exercise price of the November 2017 Warrants held by such institutional investors to $29.68 and to extend the expiration date of the warrants that were to expire on November 27, 2018 to November 27, 2019. The number of common shares underlying the warrants that were repriced did not change. The repriced warrants are exercisable for 554,322 shares of common stock in the aggregate, of which, following such amendment, half expire on November 27, 2019 and half expire on November 27, 2024. The repricing of the warrants was accounted as an equity financing cost, with no impact to net proceeds from the offering. Series G Convertible Preferred Stock and March 2019 Offering: On March 12, 2019, the Company closed on an underwritten public offering of common stock, Series G convertible preferred stock and warrants to purchase shares of common stock for gross proceeds of $12.4 million, which included the full exercise of the underwriter’s over-allotment option to purchase additional shares and warrants (“March 2019 Offering”). Net proceeds totaled approximately $11.0 million after deducting the underwriting discounts and commissions and other costs associated with the offering. The Series G convertible preferred stock included a beneficial conversion amount of $4.5 million, representing the intrinsic value of the shares at the time of issuance. This amount is reflected as an increase to the loss per share allocable to common stockholders in the years ended December 31, 2019. The March 2019 Offering was comprised of 455,178 shares of common stock priced at $5.25 per share and 1,910,536 shares of Series G convertible preferred stock, convertible into common stock at $5.25 per share. Each share of Series G convertible preferred stock and each share of common stock was accompanied by a Series 1 warrant and a Series 2 warrant. The Series 1 warrants are exercisable into 2,365,714 shares of common stock and the Series 2 warrants are exercisable into 2,365,714 shares of common stock. Series 1 warrants expire on the fifth anniversary of the date of issuance and are exercisable at $5.25 to purchase one share of common stock. Series 2 warrants expire on the earlier of: (i) the eighteen-month anniversary of the date of issuance and (ii) the 30th trading day following the public announcement of the receipt from the U.S. Food and Drug Administration of clearance or approval of a modification to the product label for the Aquadex System to include pediatric patients. Series 2 warrants are exercisable at $5.25 per share of common stock. The conversion price of the Series G convertible preferred stock as well as the exercise price of the warrants are fixed and do not contain any variable pricing features, nor any price based anti-dilutive features apart from customary adjustments for splits and reverse splits of common stock. The Series G convertible preferred stock included a beneficial ownership limitation of 4.99% but had no dividend preference (except to extent dividends are also paid on the common stock), liquidation preference or other preferences over common stock. The securities comprising the units were immediately separable and were issued separately. As of December 31, 2019, all 1,910,536 shares of the Series G convertible preferred stock had been converted into common stock and none remained outstanding. October and November 2019 Offerings: On October 25, 2019, the Company closed on a registered direct offering of 575,830 shares of common stock at a price of $1.15 per share, for gross proceeds of approximately $660,000, prior to deducting commissions and expenses related to the transaction. In a concurrent private placement, the Company agreed to issue to the investors in the registered direct offering unregistered warrants to purchase up to 575,830 shares of its common stock at an exercise price of $1.41 per share, which will be exercisable six months from the date of issuance, and will expire five years from the initial exercise date. On November 6, 2019, the Company closed on a registered direct offering of 1,219,076 shares of common stock, or common equivalents, at a price of $1.12 per share, for gross proceeds of approximately $1.36 million prior to deduction of commissions and offering expenses related to the transaction. In a concurrent private placement, the Company agreed to issue to the investors in the registered direct offering unregistered warrants to purchase up to 1,219,076 shares of our common stock at an exercise price of $0.9942 per share, which were exercisable upon the date of issuance, and will expire five years from the initial exercise date. The unregistered warrants issued in each offering were subsequently registered pursuant to a registration statement on Form S-1 that was declared effective by the SEC on December 30, 2019. Placement Agent Fees: In connection with the issuance of the Series F convertible preferred stock, the July 2018 Offering, the March 2019 Offering, and the October and November 2019 Offerings the Company paid the placement agent an aggregate cash placement fee equal to 8% of the aggregate gross proceeds raised in the offering and issued no warrants to the placement agent. Market-Based Warrants: On May 30, 2019, the Company granted a market-based warrant to a consultant in exchange for investor relations services. The warrant represents the right to acquire up to 100,000 shares of the Company’s common stock at an exercise price of $3.18 per share, the closing stock price of the Company’s common shares on May 30, 2019. The warrant is subject to a vesting schedule based on the Company achieving certain market stock prices within a specified period of time. The warrant expires on May 30, 2024. The warrant was valued at $1.93 per share using the Monte Carlo valuation methodology and is being expensed over the term of the consulting engagement which is twelve months. Significant inputs used for the Monte Carlo valuation were the expected stock price volatility of 136.21%, and management’s expectations regarding the timing of regulatory clearance for an expanded label in pediatrics. None of these warrants had vested as of December 31, 2019.

Note 5—Shareholders’ Equity

Series F Convertible Preferred Stock: On November 27, 2017, the Company closed on an underwritten public offering Series F Convertible Preferred Stock and warrants to purchase shares of common stock for gross proceeds of $18.0 million. Net proceeds totaled approximately $16.2 million after deducting the underwriting discounts and commissions and other costs associated with the offering.

The offering was comprised of Series F convertible preferred stock, convertible into shares of the Company’s common stock at an initial conversion price of $63.00 per share. Each share of Series F preferred stock was accompanied by a Series 1 warrant, which was to expire on the first anniversary of its issuance, to purchase 16 shares of the Company’s common stock at an exercise price of $63.00 per share, and a Series 2 warrant, which expires on the seventh anniversary of its issuance, to purchase 16 shares of the Company’s common stock at an exercise price of $63.00 per share. The Series F preferred stock has full ratchet price based anti-dilution protection, subject to customary carve outs, in the event of a down-round financing at a price per share below the conversion price of the Series F preferred stock (which protection will expire if, during any 20 of 30 consecutive trading days, the volume weighted average price of the Company’s common stock exceeds 300% of the then-effective conversion price of the Series F preferred stock and the daily dollar trading volume for each trading day during such period exceeds $200,000). The exercise price of the warrants is fixed and does not contain any variable pricing features, nor any price based anti-dilutive features, apart from customary adjustments for stock splits, combinations, reclassifications, stock dividends or fundamental transactions. A total of 18,000 shares of Series F Convertible Preferred Stock initially convertible into 286,714 shares of common stock and warrants to purchase 573,310 shares of common stock were issued in the offering.

As noted below, effective July 3, 2018, the conversion price of the Series F convertible preferred stock was reduced from $63.00 to $29.68, the per share price in the July 2018 Offering described below. Effective March 12, 2019, the conversion price of the Series F convertible preferred stock was reduced from $29.68 to $5.25, the per share price to the public of the Series G convertible preferred stock which closed in an underwritten public offering on March 12, 2019. Effective October 25, 2019, the conversion price of the Series F convertible preferred stock was reduced from $5.25 to $1.41, and on November 6, 2019 from $1.41 to $0.9942, the per share price to the public in the October and November 2019 transactions, respectively, described below.

As of December 31, 2019, and 2018, 535 shares of the Series F convertible preferred stock remained outstanding.

July 2018 Offering: On July 3, 2018, the Company closed on an underwritten public offering of 181,941 shares of its common stock at a public offering price of $29.68 per share, for gross proceeds of $5.4 million, including the full exercise of the underwriters’ over-allotment option to purchase additional shares of the Company’s common stock (the “July 2018 Offering”). Net proceeds totaled approximately $4.6 million after deducting underwriting discounts and commissions and offering expenses.

In connection with the July 2018 Offering, and to induce certain institutional investors who hold warrants issued by the Company in November 2017 (“November 2017 Warrants”) to participate in the July 2018 Offering, the Company entered into letter agreements with such institutional investors. Pursuant to the terms of these agreements, the Company agreed, effective July 3, 2018, to reduce the per share exercise price of the November 2017 Warrants held by such institutional investors to $29.68 and to extend the expiration date of the warrants that were to expire on November 27, 2018 to November 27, 2019. The number of common shares underlying the warrants that were repriced did not change. The repriced warrants are exercisable for 554,322 shares of common stock in the aggregate, of which, following such amendment, half expire on November 27, 2019 and half expire on November 27, 2024. The repricing of the warrants was accounted as an equity financing cost, with no impact to net proceeds from the offering.

Series G Convertible Preferred Stock and March 2019 Offering: On March 12, 2019, the Company closed on an underwritten public offering of common stock, Series G convertible preferred stock and warrants to purchase shares of common stock for gross proceeds of $12.4 million, which included the full exercise of the underwriter’s over-allotment option to purchase additional shares and warrants (“March 2019 Offering”). Net proceeds totaled approximately $11.0 million after deducting the underwriting discounts and commissions and other costs associated with the offering. The Series G convertible preferred stock included a beneficial conversion amount of $4.5 million, representing the intrinsic value of the shares at the time of issuance. This amount is reflected as an increase to the loss per share allocable to common stockholders in the years ended December 31, 2019.

The March 2019 Offering was comprised of 455,178 shares of common stock priced at $5.25 per share and 1,910,536 shares of Series G convertible preferred stock, convertible into common stock at $5.25 per share. Each share of Series G convertible preferred stock and each share of common stock was accompanied by a Series 1 warrant and a Series 2 warrant. The Series 1 warrants are exercisable into 2,365,714 shares of common stock and the Series 2 warrants are exercisable into 2,365,714 shares of common stock. Series 1 warrants expire on the fifth anniversary of the date of issuance and are exercisable at $5.25 to purchase one share of common stock. Series 2 warrants expire on the earlier of: (i) the eighteen-month anniversary of the date of issuance and (ii) the 30th trading day following the public announcement of the receipt from the U.S. Food and Drug Administration of clearance or approval of a modification to the product label for the Aquadex System to include pediatric patients. Series 2 warrants are exercisable at $5.25 per share of common stock. The conversion price of the Series G convertible preferred stock as well as the exercise price of the warrants are fixed and do not contain any variable pricing features, nor any price based anti-dilutive features apart from customary adjustments for splits and reverse splits of common stock. The Series G convertible preferred stock included a beneficial ownership limitation of 4.99% but had no dividend preference (except to extent dividends are also paid on the common stock), liquidation preference or other preferences over common stock. The securities comprising the units were immediately separable and were issued separately.

As of December 31, 2019, all 1,910,536 shares of the Series G convertible preferred stock had been converted into common stock and none remained outstanding.

October and November 2019 Offerings: On October 25, 2019, the Company closed on a registered direct offering of 575,830 shares of common stock at a price of $1.15 per share, for gross proceeds of approximately $660,000, prior to deducting commissions and expenses related to the transaction. In a concurrent private placement, the Company agreed to issue to the investors in the registered direct offering unregistered warrants to purchase up to 575,830 shares of its common stock at an exercise price of $1.41 per share, which will be exercisable six months from the date of issuance, and will expire five years from the initial exercise date. On November 6, 2019, the Company closed on a registered direct offering of 1,219,076 shares of common stock, or common equivalents, at a price of $1.12 per share, for gross proceeds of approximately $1.36 million prior to deduction of commissions and offering expenses related to the transaction. In a concurrent private placement, the Company agreed to issue to the investors in the registered direct offering unregistered warrants to purchase up to 1,219,076 shares of our common stock at an exercise price of $0.9942 per share, which were exercisable upon the date of issuance, and will expire five years from the initial exercise date.

The unregistered warrants issued in each offering were subsequently registered pursuant to a registration statement on Form S-1 that was declared effective by the SEC on December 30, 2019.

Placement Agent Fees: In connection with the issuance of the Series F convertible preferred stock, the July 2018 Offering, the March 2019 Offering, and the October and November 2019 Offerings the Company paid the placement agent an aggregate cash placement fee equal to 8% of the aggregate gross proceeds raised in the offering and issued no warrants to the placement agent.

Market-Based Warrants: On May 30, 2019, the Company granted a market-based warrant to a consultant in exchange for investor relations services. The warrant represents the right to acquire up to 100,000 shares of the Company’s common stock at an exercise price of $3.18 per share, the closing stock price of the Company’s common shares on May 30, 2019. The warrant is subject to a vesting schedule based on the Company achieving certain market stock prices within a specified period of time. The warrant expires on May 30, 2024. The warrant was valued at $1.93 per share using the Monte Carlo valuation methodology and is being expensed over the term of the consulting engagement which is twelve months. Significant inputs used for the Monte Carlo valuation were the expected stock price volatility of 136.21%, and management’s expectations regarding the timing of regulatory clearance for an expanded label in pediatrics. None of these warrants had vested as of December 31, 2019.