June 11, 2012 -- Noisy hospitals have long been a major complaint among patients. Now, new research purports to show how hospital noise can possibly harm them.
The small study, published today in the Annals of Internal Medicine, found that as the overall level of noise increased in the hospital, sleep was more likely to be disrupted. When the patients' sleep was disrupted, their heart rates increased.
Researchers at Harvard Medical School studied 12 healthy adult volunteers in a sleep laboratory, using noises pre-recorded in an actual hospital -- medical monitor alarms, telephones, staff conversations, and outside traffic -- for three nights. They analyzed how the noises affected the patients' sleep and heart rate by using brain monitoring equipment and heart rate monitors.
Of the sounds that were used, sounds from medical equipment designed to alert medical staff, such as alarms, were more disruptive than the sounds of the environment or human voices. When the patients' sleep was disturbed, their heart rates increased -- even if they did not wake up.
Dr. Orfeu Buxton and Dr. Jo Solet, two of the study's authors, said they "have heard what the patients have been saying in patient satisfaction reports, which is that there is too much noise in the hospital," and they launched the study in order to better understand the types and volume of sounds that caused the most disruption while understanding how noise affects the patient.
Previous research had already shown that noise disrupts sleep -- and that these disruptions are linked to high blood pressure, higher rates of heart disease, impaired immune function, increased memory problems and depression.
"This is the first study that has actually recorded a hospital environment and systematically quantified the response of the brain and the heart rate to these sounds," Buxton said.
A noisy hospital environment that causes disturbed sleep "may lead to increased use of medicines like sedatives that have side effects such as increased falls and increased rates of delirium. This can lead to a longer hospital stay," he said.
The authors also suggest that hospital administrators need to address three key issues to create a restful environment -- the acoustics of the hospital, the routines of hospital staff, and eliminating the noises from medical equipment.
"Eighty percent of alarm monitors in patient rooms and on hospital floors have no clinical relevance," Buxton said.
Some hospitals are already ahead of the noise-canceling curve. Susan Alves-Rankin and Jason Phillips, who work in the department of Patient Services and Service Excellence at the University of California San Francisco Medical Center, say their hospital is one such institution.
"We built a brand new hospital and took many steps to reduce noise," Alves-Rankin said, adding that the changes include noise-reducing flooring from Sweden and a silent nurse calling system to eliminate electronic noises. They are currently piloting a program using special sound masking devices in their noisiest hospital units to decrease noise and increase privacy.
Other efforts to reduce noise range from using sound absorbent materials during the design and construction phase of new hospitals to educating staff about being aware of their noise levels. At the new Shapiro Cardiovascular Center at Brigham Women's Hospital in Boston, special acoustical insulation and ceiling tiles were used during construction.
Several hospitals are using traffic light indicators to make staff more aware of their noise levels. When noise escalates, the traffic light changes from green to yellow; and when noise is too loud, the light turns red. Other hospitals have noise reduction campaigns in place.
"[The campaigns] are not only a satisfier for patients, but our staff is happy about having some more restful periods as well," said Tom Moore of the University of Iowa Hospitals.
Dr. Vineet Arora of the University of Chicago, who studies the sleep quality of patients in the hospital setting, says "we need to generalize the findings [of this study] to real patients in an actual hospital setting" and change the culture of the hospital where "patients are empowered to talk to their doctors about their sleep needs."
The hope is that when patients have a quiet environment where they can sleep and heal, patient outcomes may improve. When the dial on hospital noise is turned down, Solet says, "we can expect decreased lengths of stay and lower rates of re-admission."