Some 2,200 registered nurses from six hospitals will return to work this week after ending a four-week strike that at one point involved 4,000 nurses from eight hospitals, union officials said. Of the 1,200 California Nurses Association members who voted Sunday, 77 percent approved a new contract, which offers a 21 percent wage increase over 34 months. The pact differs little from one rejected 11 days ago. The nurses are set to return to work on Wednesday, said CNA spokeswoman Maureen Anderson. Although 10 other hospitals were unaffected by the walkout, hundreds of patients were inconvenienced as some of the struck medical facilities closed emergency rooms, delayed surgeries and consolidated many other services. While many nurses weren't elated with the agreement, they said they demonstrated labor solidarity. ``We've put this message out to the hospitals: That nurses are serious about the issues facing them and we intend to be listened to,'' said Mary Scheib, a CNA nurse at Mt. Zion Hospital. ``We're going to be continuing our efforts (to improve pay and working conditions) when we go back to work,'' she added. ``Today is really day one of organizing for 1991, when the contract expires.'' A proposed CNA contract voted down Aug. 19 by a 2-1 margin offered 20 percent over 36 months. CNA went into the strike Aug. 2 demanding a 21 percent wage increase over two years. Karen Henry, chief negotiator for Affiliated Hospitals, the group representing the affected medical facilities, said Sunday that the CNA contract ``accomplished the hospitals' bargaining objectives.'' She defined that mainly as avoiding large pay raises in a two-year period. Under the CNA contract, a dayshift nurse at top scale will make $21.99 an hour by the end of the contract, or $45,700 annually. The 1,700 members of Local 250 of the Hospital and Health Care Workers Union, who went on strike July 26, began returning to work Wednesday. They walked out mainly over health benefits. CNA's negotiating committee unanimously endorsed the latest contract. The latest proposal was an unsolicited offer submitted Friday to Affiliated. The two sides had not met at the bargaining table for nearly a week. CNA nurses struck at Children's, Marshal Hale, St. Mary's, St. Francis and Mount Zion hospitals in San Francisco and Seton Medical Center in Daly City. Local 250 accepted a contract last week that provides up to 6 percent pay raises for nurses and some other hospital workers over two years. Some other workers will not receive raises, but bonuses ranging up to $300 by the end of the contract. About 100 nurses and service workers remain on strike at French Hospital, where talks have been held separately. A settlement there is expected to be routine.