ASHRAE LV-11-C031-2011 Measured Levels of Hospital Noise Before During and After Renovation of a Hospital Wing and a Survey of Resulting Patient Perception.pdf

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1、 Cassandra H. Wiese is a graduate student in the Architectural Engineering Program at the University of Nebraska Lincoln, Omaha, NE. Lily M. Wang is an associate professor in the Durham School of Architectural Engineering and Construction at the University of Nebraska Lincoln, Omaha, NE. Measured Le

2、vels of Hospital Noise Before, During, and After Renovation of a Hospital Wing, and a Survey of Resulting Patient Perception Cassandra H. Wiese Lily M. Wang, PhD, PE Student Member ASHRAE Member ASHRAE ABSTRACT Acoustic conditions in hospitals can negatively influence a patients physical and psychol

3、ogical health. This paper reports on noise levels measured before, during, and after renovation of a hospital wing in an Omaha, Nebraska, facility that regularly receives unsatisfactory noise scores on patient satisfaction surveys. Sound pressure levels were logged every 10 seconds over four-day per

4、iods in three different locations: at the nurses station, in the hallway, and in a nearby patients room. The resulting data have been analyzed in terms of A-weighted equivalent sound levels (LAeq) as well as various exceedance levels (Ln). Results indicate that sound levels did not change much due t

5、o the renovation, due to a reduction in the scope of the renovation after the start of this project. The noise levels measured did regularly exceed currently recommended guidelines for hospital noise, though. A concurrent subjective survey on patient perception of hospital noise was conducted in the

6、 hospital wing during and after the renovation. Results from that survey show that patients in this hospital wing were most concerned with noise that originates from within their room, often linked to medical equipment or their roommate. The heating, ventilation, and air-conditioning systems ranked

7、quite low among noise sources of concern at this facility. Based on the survey results, it does not seem that adding absorptive materials to the hallway or nearby nurses stations would reduce noise from the sources considered most bothersome by the patients in this case study. INTRODUCTION Noise in

8、hospitals has become a topic of growing concern in recent years, since it is often cited as a major complaint by patients in hospitals (Busch-Vishniac et al 2005). Busch-Vishniac et al (2005) reported that noise levels in hospitals have been increasing steadily since 1960, with current background no

9、ise levels averaging 72 dBA during the day and 60 dBA at night. These values are much higher than the guidelines set by the World Health Organization (1999), which recommend that the A-weighted equivalent sound levels (LAeq) in hospital rooms not exceed 35 dBA during the day and 30 dBA at night. Unf

10、ortunately, research over the past 45 years has found that noisy conditions in hospitals lead to many non-auditory effects on patients and staff (Christensen 2005, Ryherd et al 2008). In particular, patient well-being is negatively impacted through sleep deprivation caused by noise disturbances (Top

11、f et al 1996, Freedman et al 1999, Parthasarathy and Tobin 2004). Higher noise levels also increase patient stress levels, all of which can lead to increased amounts of pain medication, lengths of hospital stay, and wound healing times (McCarthy et al 1991). Minckley (1968) reported that higher leve

12、ls of noise in a surgical recovery room were linked to a higher percentage of patients receiving pain medication; however, the data was only collected over five random work days. Another study found that cataract patients who experienced higher levels of noise LV-11-C031256 ASHRAE Transactions2011.

13、American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (www.ashrae.org). Published in ASHRAE Transactions, Volume 117, Part 1. For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAES prior

14、 written permission.due to the presence of nearby construction tended to require longer hospital stays, although the actual sound levels were not measured (Fife and Rappaport 1976). Other investigations have shown that higher levels of noise reduced the speed of wound healing in rats (Wysocki 1996);

15、 no definitive findings have been made regarding human wound healing, though. In addition to affecting patient health, acoustical conditions in a hospital have also been correlated to patient perception of the quality of care received. A study by Hagerman et al (2005) placed patients in an intensive

16、 coronary care unit which either had ceiling tiles that produced a quality or poor acoustical environment. Those in the quality acoustic environment responded in subjective surveys that they were more satisfied with their care, and these patients also saw less re-hospitalization rates. At a hospital

17、 in Omaha, Nebraska, responses from Press-Ganey Patient Satisfaction Surveys regularly indicate that noise in their hospital is an aspect about which patients express great dissatisfaction. Consequently, baseline noise level measurements were made by the authors in four similar wings at the hospital

18、 which had different material treatments (Wiese et al 2009). Results showed that acoustical material treatment such as absorptive ceiling tile and carpet did lower the ambient noise level (or the low-end) by just perceptible amounts; however, the peak levels (or high-end) did not vary greatly except

19、 in the neonatal intensive care unit (NICU), where other environmental controls have been instituted. In the NICU, the lighting levels are much dimmer than in other wings; also there are visual alarms that indicate if the noise level exceeds a certain amount. It is the authors belief that both the a

20、mbient and the peak noise levels need to be addressed to improve the acoustical environment in hospitals. Lowering ambient levels through using more acoustically absorptive materials may reduce the overall stress caused by the environment, while reducing peak levels through other environmental or be

21、havioral modifications may improve the likelihood that patients experience long restorative periods without noise interruption. Note that noise from the heating, ventilation and air-conditioning system was not an obvious cause of concern in these cases. Subsequent to these findings, the hospital pla

22、nned a renovation of one wing with the goal of incorporating both material and environmental changes to reduce the impact of noise on patient well-being. More absorptive materials were to be installed, as well as visual alarms and dimmed lighting at night. This paper reports on the objective and sub

23、jective data gathered before, during, and after the renovation. Objective measurements of the sound levels in that wing have been taken, before, during, and after the renovations were completed, while subjective data regarding patient perception were gathered only during and after the renovations, d

24、ue to delays in receiving approval of the study from the hospitals Institutional Review Board. Other researchers have found that implementing assorted material, environmental and/or behavioral changes can impact measured sound levels or patient perception (Webber 1984, Kahn et al 1998). MacLeod et a

25、l (2005) documented that adding absorptive materials to the hallway of a cancer unit at Johns Hopkins Hospital lowered sound levels and improved patient satisfaction; only 17 patients submitted the short five-question survey, though. Another study reported the results of a behavioral modification pr

26、ogram in an intensive care unit, in which staff members were educated about the importance of sleep, and non-disturbance periods were implemented from 1-3 PM and 12-5 AM (Monsen et al 2005). Nursing staff were asked to document sleep disturbance factors for nine patients over a period of two weeks b

27、efore and two weeks after the behavioral modification program, while sound levels were also recorded. Findings indicate that the intervention did reduce the number of sleep disturbance factors, as well as lower noise levels in some measure. However, patients were not polled for their own impressions

28、. Taylor-Ford et al (2008) measured sound levels and gathered noise perception data from both patients and staff, before and after a noise reduction program that included staff education about noise, the use of a visual alarm, and other minor physical alterations to the unit. These particular interv

29、entions did not yield statistically significant changes in overall sound levels, but patients and employees reported fewer disturbances after the interventions. Overman Dube et al (2008) conducted a similar study, surveying 30 patients before and after an intervention that included education of and

30、behavioral modifications by the staff (e.g. soft voices, closing doors, limiting overhead paging) and assorted environmental changes (e.g. dimming lights). While the measured noise level readings increased 4 dB from pre-intervention to post-intervention, the perception of bothersome noise decreased

31、as reported by both patients and staff. Evidence from another investigation highlights that changing staff behavior through noise awareness and education programs can reduce peak noise levels significantly but not 2011 ASHRAE 257ambient levels (Richardson et al 2009). The findings from these investi

32、gations all support the hypothesis that reducing peak levels through environmental or behavioral interventions may have a greater impact on patient perception, more so than reducing ambient levels. Results from Stanchina et al (2005) further suggest that reducing the relative range between peak leve

33、ls and ambient ones may be more important than only reducing absolute peak levels, since a smaller difference between peak and ambient levels reduced the number of sleep disruptions experienced by patients. More research is needed, however, to determine the upper limit for how much the ambient level

34、 may be raised before becoming a problem itself. The project presented in the current paper includes more detailed acoustic measurements and a longer time period over which data on patient perception was accumulated than in many of the previous studies. Exceedance levels (Ln) are calculated in addit

35、ion to LAeq; specifically, L10is the sound level exceeded 10% of the time, giving an approximate range of peak noise levels, while L90is the sound level exceeded 90% of the time, giving an approximate range of ambient noise levels. Unfortunately, the material and environmental changes that were orig

36、inally planned to the hospital ward under study were not fully implemented, which limited the significance of this projects findings regarding the benefit of the intervention. The data gathered from the patient surveys, however, remain useful towards understanding what type of interventions may have

37、 the most notable impact on the noise sources of greatest concern in this facility, as discussed below. RESEARCH METHODOLOGY Experimental Procedures The hospital wing being investigated includes twenty double occupancy patient rooms along its outside corridor, with a centralized nurses station and s

38、torage areas in the center (Figure 1). The flooring materials are hard linoleum in the hallway and patient rooms, and carpet in the nurses station. Standard absorptive acoustical ceiling tile are found in the hallway and nurses station, while the patient rooms have hard drywall ceilings. The walls o

39、f all the spaces are painted drywall. Sound level measurements were made with calibrated Larson Davis 824 sound level meters at three time periods: before (December 2009), during (March 2010), and after (June 2010) renovations to the wing. Three meters were used, one at each of the following locatio

40、ns marked in Figure 1: the nurses station, a patient room, and the hallway. The meters logged data on sound levels and frequency spectra every 10 seconds continuously over a four-day work week from Monday through Thursday, simultaneously at all three locations. Figure 1 Floor plan of the hospital wi

41、ng under study. Black dots indicate the locations of sound level meters. A survey on patient perception of hospital noise developed by the authors (Figure 2) was distributed to patients who met the following criteria. Subjects were at least 19 years old or older, able to read English, able to cognit

42、ively understand the survey as determined by the distributing staff, and must have stayed at least one night in the hospital wing (all the patient 258 ASHRAE Transactionsrooms in this wing appeared to have similar acoustic characteristics to the one in which sound level measurements were taken). The

43、 survey gathered data on age, gender, hearing impairment, and sensitivity to noise, as well as responses regarding how disturbed the subjects were by noise during the day and night, what noise sources were most bothersome, how difficult it was to hear spoken information, and how easily they overhear

44、d others discuss private patient information. The nursing staff assigned to this wing assisted with distributing and collecting the surveys from eligible subjects upon their being discharged from the hospital. Due to delayed approval of the subjective portion of the study by the hospitals Institutio

45、nal Review Board, the survey was only distributed during and after renovations, which spanned a period of three and a half months. Figure 2 The survey instrument used to gather data on patient perception of hospital noise. Data Analysis The sound level meter measurements were analyzed within Microso

46、ft Excel to calculate LAeq, L10and L90over a variety of time periods: the overall values over each 4-day measurement period; the daily daytime values between the hours of 7 AM to 10 PM; and the daily nighttime values between the hours of 10 PM to 7 AM. Spectral data were also examined. With regards

47、to the patient survey, responses to each survey question were coded numerically and input into the statistical analysis software SPSS (v18) for further analysis. Because many of the responses did not demonstrate normal or symmetric distributions, non-parametric tests were used to analyze the data, i

48、ncluding Chi-square tests, Kruskal-Wallis tests, 2011 ASHRAE 259and Mann-Whitney U tests (Field 2005, Pallant 2007). The accepted level of significance for all analyses was p0.05. The statistical tests were used to determine if there was any statistically significant difference between the responses

49、 gathered during the renovation and those gathered after the renovation. Also the statistical analyses indicated which responses to the different questions were significantly correlated (e.g. sensitivity to noise and degree of annoyance caused by hospital noise). RESULTS Objective Measurements A plot of the measured sound levels (overall LAeq, average daytime LAeq, and average nighttime LAeq) can be found in Figure 3. The values range between 51 and 63 dBA, much higher than WHO guidelines for day or night. When comparing the levels at each location taken before, dur