STRESS

Noise

The operating room is a noisy environment, with surgical drills, saws, monitor alarms, and conversation all competing for the anesthesiologist's attention. The flat, water-impermeable walls of the modern operating room are outstanding reflecting surfaces for sound. Studies have shown that the effects of noise on people depend primarily on the duration and the timing of the sounds. The intensity of sound is displayed on a logarithmic scale and is reported in decibels (dB). A measured increase of 10 dB implies that the intensity of a sound has increased 10-fold. Sound-level meters are commonly biased to the A-weighted scale (dBA), which is thought to give a reasonably accurate measure of the response of humans to sound. Conversational speech, lecture-level speech, and nearby shouted speech have intensities of about 55, 65, and 75 dBA, respectively. OSHA standards mandate the use of protective devices in environments where continuous sound intensities and the duration of exposure are at least 90 dB and 8 hours, respectively. In addition to disrupting communication, unpleasant or unexpected noises may hinder concentration and thereby contribute to physiologic stress.^[103]

Noise levels in operating rooms can easily approach those from a diesel engine. Particularly loud are such actions as opening packages of gloves (86 dBA), striking instruments together (80 dBA), moving equipment (60 to 80 dBA), conversing (66 to 72 dBA), power drills, and various objects striking floors.^[104] The intensities of most of these sounds are greater than the intensity of normal conversation, 55 dBA. Nonspecific tones from monitors and surgical equipment, especially when several are sounding alarms at once, though perhaps not loud enough to impair communication, may also add to the confusion. Simultaneous conversations and other distracting sounds are frequently louder than the tones produced by monitors such as electrocardiography machines, pulse oximeters, and equipment alarms. If these unnecessary auditory diversions hamper communication between anesthesiologists during stressful events in patient management, they should be stopped. Loud sounds have been shown to contribute to stress, as measured by responses of the pituitary-adrenal axis. In addition to affecting health care workers, the din of the operating room and other acute care areas can be disconcerting to conscious patients.^[105] Although noise is not known to cause problems other than hearing loss, it appears prudent to limit unnecessary sources in the operating room.