ResMed, a San Diego company that makes devices and software for sleep issues, reported that revenue rose to $601.3 million in the second quarter, a 13 percent year-over-year increase.

“We had a strong quarter with double-digit revenue and operating profit growth” Mick Farrell, ResMed’s CEO, said in a news release on Jan. 22. “Our masks have performed well around the world, device sales are solid, and our cloud-based software continues to grow rapidly.”

Income from operations came to $146 million, a 51 percent increase compared with the prior year’s total.

But gross margin in the second quarter was 58.2 percent, lower than 58.3 percent in quarter two of the previous year, mainly due to declines in prices, which were partially offset by manufacturing and procurement efficiencies, according to the company.

Selling, general and administrative expenses were $151.8 million, a 9 percent year-over-year increase, or a 6 percent increase on a constant currency basis. These expenses represented 25.2 percent of revenue in the quarter, compared with 26.3 percent in the prior year’s quarter.