Floor Vibrations on Healthcare Facilities: A Case Study on a Surgical Microscope

Abstract

The paper describes a vibration issue experienced on a surgical microscope and presents the results of a series of dynamic testing to resolve the issue. The microscope is located in an operating room (OR) on the fourth floor of a 10-story, steel framed, inpatient hospital building constructed in 2011. The fifth floor of the building is a mechanical space. On multiple occasions, neurosurgical cases have been disrupted due to the vibrations of the microscope. The microscope manufacturer did not provide any specific vibration limits. Generic vibration criteria available in the literature are provided for floors—with no reference to the eye vibrations of a microscope—and limit neurosurgery floor vibrations to 1,000 micro-in/s (mips) in RMS. An independent vibration criterion for the eye (3,500 mips) has been developed over the series of tests by comparing the subjective perception/tolerance of the OR personnel against the measured data. The largest vibration levels measured at the eye reached 10,000 mips at 21 Hz and coincided with the motor speed of a condenser water pump operating at 1,260 RPM on the fifth floor. Comparisons of floor and eye vibrations in the OR indicate that microscope amplifies the floor vibrations three to four times at 21 Hz.