A health insurance bill intended to protect more than 30 million elderly Americans from the financial ravages of serious illness is one short step away from final congressional approval.

"It's a landmark accomplishment, and it's going to remove an awful lot of fear from the minds of over 30 million seniors," Rep. Pete Stark, D-Calif., said after the House voted 328-72 Thursday to approve a catastrophic health insurance bill.The measure goes to the Senate where similarly overwhelming approval is assured, probably next week. It represents the biggest expansion of Medicare in the program's 23-year history.

Originally proposed by President Reagan more than a year ago - albeit in a less expansive version - the legislation is intended to protect the nation's 32 million Medicare beneficiaries from financial ruin stemming from illnesses that run up big hospital and doctor bills.

"The legislation will go a long way to alleviate the fears that elderly people have about being wiped out from financial costs when catastrophic illness hits," said Rep. Henry Waxman, D-Calif., who with Stark was a major mover in the project.

Waxman acknowledged that the measure does not address the problem of nursing home and other long-term costs for people not sick enough to be hospitalized, but unable to live alone.

"That has to be No. 1 on our agenda for the next breakthrough in the health area," said Waxman.

Although the final House-Senate version was considerably enriched along the way - mainly by the addition of an outpatient prescription drug benefit - Health and Human Services Secretary Otis R. Bowen has said he will ask President Reagan to sign the measure, which House Speaker Jim Wright has called "the most important health initiative in recent years."

The bill provides full hospital coverage after a once-a-year deductible estimated at $564 in 1989 and indexed to hospital inflation. Medicare now pays full charges for no more than 59 days a year and the recipient is subject to a deductible for each hospitalization.

The cap on costs for physicians is $1,370 a year. After a $75 deductible, Medicare now pays 80 percent of approved doctor bills, and that part of the program remains intact. Starting in 1989, however, the $75 deductible and the 20 percent share paid by beneficiaries count toward the $1,370 cap. After that is reached, Medicare pays 100 percent of approved doctor bills.

However, the beneficiary will remain liable for any portion of doctor bills that exceed the fees approved by Medicare.

Here are Utah and Idaho votes in the 328-72 roll call Thursday by which the House approved a House-Senate compromise bill adding catastrophic illness coverage to the Medicare program.

A "yes" vote is to pass the bill. Y is a yes vote. N is a no vote. X denotes those not voting.

UTAH

Democrat - Owens, Y.

Republicans - Hansen, X; Nielson, N.

IDAHO

Democrat - Stallings, Y.

Republican - Craig, N.