Spectramed Inc. of Newport Beach, which makes devices to monitor patients' vital signs during surgery, reported a fourth-quarter loss of $2.1 million, bringing its total losses for 1987 to nearly $3.7 million. By contrast, Spectramed lost $6.9 million in the fourth quarter of 1986. Although the company has not posted a profitable quarter in its 15-month history, business has been improving, said Chuck French, the company's chief financial officer. In the fourth quarter of 1987, the company achieved record sales of $19.9 million--up 6% or $1.1 million from the same period in 1986. French said Spectramed achieved a $1.1-million operating profit in the fourth quarter, but the company showed a loss because it budgeted $3.2 million in costs projected for the closing of a manufacturing plant in Puerto Rico. Spectramed went into business in 1986 by buying the assets of another company. At that time, French said, it had to assume a large financing debt, which has since hobbled the company's profitability. Spectramed raised $37 million toward that debt when it went public in June, but the company still owes about $50 million, French said.