The Maryland House of Delegates, apparently dooming efforts to raise Maryland's legal drinking age for beer and wine this year, reversed itself tonight and defeated a measure that would have changed the statutory minimum from 18 to 21.

"The issue is like a seriously wounded person on the operating table in this House: If we vote against it, it's deceased," said Del. Patrick L. McDonough (D-Balitmore) shortly before the 64-to-62 vote, six short of the constitutional majority needed for passage.

Earlier today, the House Judiciary Committee, which advocated the 21-year old drinking age, acted favorably on two measures sought by Gov. Harry Huges to dea more stringently with drunk drivers. The bills approved by the panel are expected to receive General Assembly approval as part of what the state's motor vehicle administrator called the most comprehensive revision of drunk driving laws in a decade.

Tonight's recondsideration of the drinking age came three days after the House had approved the measure. In the interim, there was instense lobbying by tavern owners and several delegates who either opposed any change or said they favored raising the age only to 19. In floor debate, some argued that those aged 18 to 20 would simply flock to the District, Virginia and West Virginia where the legal limit is lower.

The Senate has already voted for 19, in part because its members believed the higher age would never pass the conservative House judiciary panel. In a surprise action, however, the committee rejected 19 in favor 21, leading to accusations of "subterfuge" against the committee and its chairman Joseph E. Owens (D-Montgomery).

The measure voted on twice this week was a judiciary committee-amended version of a bill with 63 co-sponsors that originally would have raised the age from 18 to 19. Del. Patrick Scanello (D-Anne Arudel), who introduced it in its original form, said tonight he was afraid the measure raising the age to 21 would expire in a conference committee of the House and Senate or through a veto by Gov. Harry Hughs, who prefers 19.

"I am pretty much confused," said Scanello, who voted against this amended bill Tuesday and ending up abstaining tonight."I'm between a proverbial rock and a hard place and I don't know where to go."

Owens, an opponent of the 1974 legislation lowering the age to 18 in Maryland, argued tonight that only by adopting the upper limit would the lawmakers stop the "trickle-down effect" by which 18-year-olds buy beer for 16- and 17-year-olds, increasing the incidence of alcoholism among teen-agers.

"The trickle-down theory sounds like something out of Republican economics," scoffed Del. Timothy Maloney (D-Prince George's). "D.C. liquor stores are licking their chops over this bill." "If one's old enough to fight and die, one's old enough to have a beer," asserted his collegue, Del. Thomas Mooney (D-Prince George's).

Proponents of 19 scheduled another reconsideration vote for Monday, but their procedural strategy was questioned by House Speaker Benjamin L. Cardin, suggesting its chances were extremely slim at best.

Before the session started, similar odds were given for some of the drunk driving reform measures that emerged from a governors task force last year. With Owens' committee perceived as the bottleneck, victims of drunk drivers and their supporters mounted a major lobbying effort that largely succeeded.

The bills approved by the Judiciary Committee today would mandate license suspensions for those refusing chemical tests to determine alcohol content of their blood and make court dispositions of probation before judgement in drunk driving cases available to law enforecement officers and judges. That information is not now available.

William V. Bricker, administrator of the Department of Motor Vehicles, beamed as the panel approved, and in some instances strengthened, the measures, which are sought by Hughes and the governor's task force on drunk driving. "It's beautiful, it really is," said Bricker. "It's better than we'd hoped for. This is the biggest highway safety package we've gotten in 19 years."

Members of the judiciary panel as well as Bricker described the measure recording probation before judgement -- a verdict that results in no description of the offense for which it is given -- as the most important part of the governor's package because it will enable judicial officers to identify repeat drunk driving offenders who might appear otherwise as first-time violaters.

In approving another bill requiring a 60-day license suspension for refusal to take a blood or breath alcohol test, the committee reluctantly accepted an amended Senate bill giving the state's Motor Vehicle Administration the option of permitting such an offender to drive to and from work or in the course of his employment.

The committee tacked on another amendment of its own, however, that strengthens another section dealing with whether or not a person must expressly consent to such a test. In Maryland drivers must sign a consent form, while in other states, the law states that such law is implicit.The amandment would do away with the consent form. Bricker said the deletion would permit police officers to administer such tests to juveniles without having to seek parental permission.

Last year, he said, the express consent provision had resulted in 75 refusals by juveniles stopped for driving under the influence of alcohol.