Inogen (NSDQ:INGN) today affirmed its guidance for the rest of this year and issued its 2015 financial forecast, saying it expects to post top-line growth of 20% to 25% over 2014.

The respiratory products maker said it still expects adjusted net income of between $5.5 million and $6 million on sales of $106 million to $110 million this year.

For 2015, Inogen forecast for adjusted net income of $8 million to $9.5 million, on sales growth of 20% to 25%, or between $130 million and $135 million – fueled in part by a more than 30% expected rise in direct-to-consumer sales.

“The company expects positive cash flow for the year with no additional equity capital required to meet its current plan,” Inogen said in a press release.

Inogen reported that 2013 revenue soared 55% year-over-year, to $75.4 million. Net income rose to $18.2 million, or $1.10 per share, from a loss of $5.2 million, or $19.97 per share, for the previous year. Excluding a 1-time tax benefit, Inogen would have posted 2013 earnings of $3.6 million, the Goleta, Calif.-based company said.

“Oxygen therapy is a large and growing market opportunity estimated to include 2.5 to 3 million patients in the U.S. and representing an approximately $3 to $4 billion market. Portable oxygen concentrators continue to be the fastest-growing oxygen equipment segment in the United States,” CEO Raymond Huggenberger said in prepared remarks. “In 2013, Inogen was the leading POC supplier in the U.S. for Medicare patients. That momentum has continued into 2014 as we saw better-than-expected results from our direct-to-consumer sales strategy shift, as well as an increase in domestic business-to-business sales, primarily due to consumer awareness and demand. As we look towards 2015, we see multiple avenues to drive our future growth, including the expansion of our direct-to-consumer network and an increase in our business-to-business distribution, both domestic and international.”

Inogen issued its 2015 financial forecast during a meeting with investors and analysts in New York today. The company held an initial public offering in February, raising $52.5 million after underwriting fees.

INGN shares closed up 0.3% at $24.94 apiece today. The stock is up 55.9% since its March debut at $16 per share.