ST. LOUIS • Trimming medical costs is the latest mantra among hospital executives, government bureaucrats, insurers and benefit managers as they grapple for ways to contain U.S. health care spending. But executive compensation in the health care industry shows few signs of hitting a ceiling. One sure bet: The salaries and benefits for hospital administrators will continue to rise. A recent survey by Equilar, an executive compensation data firm based in Redwood City, Calif., found that — for the fourth time in five years — health care chief executives commanded the highest pay packages last year among publicly traded companies.