Sunrise Medical Inc. warned that its fiscal fourth-quarter results would fall substantially below analysts' estimates of 12 cents a share. The Carlsbad-based company, which makes medical rehabilitation devices, also said it would nearly double the number of planned layoffs to about 600 positions, or 12% of its worldwide work force. The cuts are expected to have one-time costs of $4 million in the fourth quarter, or 11 cents a share, the company said, adding that it will generate about $18 million in annual savings. The company said that the warning was due in part to slim margins at its Home Healthcare unit and because of a projected operating loss at its Continuing Care unit. Sunrise's announcement came after the close of U.S. markets. Its shares fell 13 cents to close at $6.69 on the New York Stock Exchange.