Patients’ Perception of Noise in the Operating Room—A Descriptive and Analytic Cross-Sectional Study Dorthe Hasfeldt, MSC, RNA, Helle Terkildsen Maindal, PhD, MPH, Palle Toft, PhD, MD, Regner Birkelund, PhD, MSC Purpose: Noise is a general stressor that affects the cardiovascular system, resulting in increased blood pressure and heart rate, both of which can be problematic for the patient preparing for anesthesia and surgery. The purpose of this study was to investigate the patient’s perception of noise in the OR before anesthesia, the correlation between the actual noise levels and the patient’s perception of noise, and if there are particular patient subgroups that are especially vulnerable to noise. Design: This cross-sectional study was performed within a mixed descriptive and analytical design, including 120 patients (60 acute/60 elective) undergoing general anesthesia for orthopaedic surgery. Methods: Data collection consisted of registration of demographic variables and measurements of noise levels in the OR combined with a questionnaire. Findings: Results showed that 10% of the patients perceived noise levels in the OR as very high and experienced the noise as annoying, disruptive, and stressful. There was no correlation between the actual noise levels to which patients were exposed and their perception of noise. Acute patients perceived significantly more noise than elective patients (P , .01), although they were actually exposed to less noise. Of the acute patients, those undergoing major surgery perceived more noise than patients undergoing minor surgery (P , .01), although actually exposed to less noise. There was a significant correlation between patients’ sense of coherence (SOC) and their perception of noise (P , .01). Most patients who perceived noise levels as very high had a SOC below 50 (scale: 13-91). Conclusions: Perianesthesia nurses need to maintain their focus on keeping noise levels in the OR as low as possible. When caring for acute patients, patients undergoing major surgery and patients with a low SOC perianesthesia nurses should be particularly aware, as these patients might be more vulnerable to noise.
Keywords: noise, operating room, patient perspective, sense of coherence, research, perianesthesia. Ó 2014 by American Society of PeriAnesthesia Nurses
Dorthe Hasfeldt, MSC, RNA, PhD student, Odense University Hospital, Department of Anesthesiology and Intensive Care, Denmark; Helle Terkildsen Maindal, PhD, MPH, Associate Professor, Aarhus University, Department of Public Health, Denmark; Palle Toft, PhD, MD, Professor, Odense University Hospital, Department of Anesthesiology and Intensive Care, Denmark; and Regner Birkelund, PhD, MSC, Associate Professor, University of Southern Denmark & Vejle Hospital, Denmark.
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Conflict of interest: None to report. Address correspondence to Dorthe Hasfeldt, Dept. Anesthetsiology and Intensive Care Sdr. boulevard 29, Intrance 5, 5000 Odense C, Denmark; e-mail address: d.hasfeldt@ hotmail.com. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.03.001
Journal of PeriAnesthesia Nursing, Vol 29, No 5 (October), 2014: pp 410-417
NOISE IN THE OR
NOISE IS A GENERAL stressor that can affect the cardiovascular system, resulting in increased blood pressure and heart rate, also known as the ‘‘startle effect.’’ This physical stress reaction provokes psychological stress responses.1-4 As such, noise in the operating room (OR) should be avoided as much as possible, particularly in the period between the patient’s arrival in the OR and until they are fully anesthetized. Patients are especially vulnerable to external stress stimuli during this period. Noise in the OR was first described in the 1970s, when Shapior and Baland5 registered noise levels in the OR and found that they equaled the level of noise on a freeway. They defined noise in the OR as ‘‘the third pollution,’’ equating noise with air and water pollution. In the Guidelines for Community Noise issued by the World Health Organization (WHO),6 it is pointed out that patients in hospital settings are particularly vulnerable to noise as their situation reduces their capacity to cope with stress. The WHO recommends that sound levels do not exceed 30 dB(A). Nevertheless, sound levels in ORs have been shown to be very high [average 50-75 dB(A), max peak 80-120 dB(A)] and in excess of the recommended levels.7 From our experience, noise is also a frequently discussed topic in clinical practice among OR staff. A literature review published in 20107 showed the topic of noise in the OR to be widely described with regards to noise levels in excess of the recommended levels,3,8-19 identifying noise sources as being related to equipment and staff behavior3,12,15,17 and identifying negative effects of noise on staff performances, mainly in relation to impaired communication.15,17,19 The review, however, revealed a lack of knowledge and understanding of the patient’s perspective. The literature on the patient’s perspective is sparse and contradictory.7 A previous study performed by Lui and Tan8 surprisingly revealed no correlation between patients’ perception of noise and the actual noise levels to which they were exposed. This could be explained by the fact that sound is perceived individually, and the degree to which a sound is perceived as noise not only depends on the character and the level of the sound but also on the person exposed to the sound and the context in which the sound is perceived. Patients in a particularly vulnerable situation, such as those facing acute surgery that they have not been able to
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prepare themselves for owing to the sudden need for surgery, might be more sensitive to the sound in the environment than patients experiencing more planned and predictable situations. Some patients might be more sensitive because their capacity to cope with stress stimuli in general is limited. According to the theory of salutogenesis, developed by the medical sociologist Antonovsky,20,21 people with a low sense of coherence (SOC) are more vulnerable to stress stimuli because they have limited general resistance resources to cope with stressful situations. According to this theory, patients’ SOC might therefore influence their perceptions of noise in the OR.
Purpose The purpose of this study was to investigate if patients undergoing general anesthesia perceive noise in the OR in the period from their arrival until they are fully anesthetized, if there is any correlation between the actual noise levels to which patients are exposed and their perception of noise, and if subgroups particularly vulnerable to noise could be identified.
Hypotheses Based on a previous study conducted by Lui and Tan,8 we hypothesized that (1) approximately 50% of the patients undergoing general anesthesia for orthopaedic surgery perceive noise in the OR in the preanesthesia period, and (2) there is no correlation between the actual noise levels to which the patients are exposed and their perception of noise. We also hypothesized that (3) acute patients perceive more noise than elective patients, and owing to the context of their situation, they are more vulnerable to noise. Additionally, we hypothesized that (4) patients with a low SOC experience more noise than patients with a high SOC.
Design This cross-sectional study was performed using a mixed descriptive and analytical design. Three types of data were collected, namely demographic variables available on the anesthesia record, noise levels in the OR, and a post recovery patient questionnaire.
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Methods Population and Inclusion The study was approved by The Investigational Committee at Odense University Hospital in Denmark and The Danish Data Protection Agency (jour.no 2011-41-5948). Data collection were conducted in two hospitals in Southern Denmark, namely one large University hospital (Odense University Hospital) and one regional hospital (Kolding Hospital). As orthopaedic ORs have been shown to be the noisiest,3,17,22 mainly because of the instruments used in orthopaedic operations, data collection were conducted in orthopaedic surgery units. A total of 60 patients undergoing acute surgery (defined by the fact that the surgery is not planned because the need for surgery arises suddenly and unexpectedly) and 60 patients undergoing elective surgery were included. Inclusion took place consecutively when patients arrived at the surgery unit. Adult patients (aged $18 years) undergoing general anesthesia (total intravenous anesthesia) for orthopaedic surgery were included. Patients with a hearing impairment, including hearing aid users, were excluded as this could negatively influence the perception of noise and thereby bias the results. Patients who, on cognitive or linguistical ground, were considered not able to read, comprehend, or fill out the questionnaire were also excluded. Patients meeting the inclusion criteria were informed about the study; and if they agreed to participate, were consented. Study enrolment was continued until 120 completed questionnaires were returned. A total of 141 patients were eligible. Of these, 21 patients (11 elective and 10 acute) were excluded from the analysis because they did not complete the questionnaire for the following reasons: Five patients did not manage to complete the questionnaire owing to postoperative stress, pain, or nausea; Four patients were hindered by linguistic or cognitive difficulties; Four patients failed to answer all the questions; and Eight questionnaires were unaccounted for. Demographic Variables Demographic variables were obtained from the anesthesia record. The demographic variables
represented the minimum information perianesthesia staff has on a patient before the patient enters the OR and included:
Sex (male/female), Age, Type (acute/elective), Surgery (minor/major), and Previous general anesthesia (yes/no).
Both operation size and severity were taken into account in determining if the surgery was minor or major. All surgery related to cancer or other life-threatening vital conditions was defined as major (Table 1). Measurement of Noise Levels The actual noise levels to which patients were exposed in the OR were recorded. The sound level in the OR was measured from the time the patient entered the room until the anesthesia staff assessed the patient to be fully anesthetized, that is, when they demonstrated no ciliary reflex and no breathing. The measurements were performed with a ‘‘Voltcraft Datalogger 322 Sound Level Meter’’ (Conrad Electronic AG, Soloturn, Switzerland), which measures noise levels in decibels (dB) on a logarithmic scale. The sound level meter was set according to the WHO recommendations6 for sound level measurements, that is, it was set to measure dB(A) using a filter that corresponds to the human ear and to ‘‘fast response time’’ in which measurements are recorded every 0.125 s. This provides the most representative measurement of human hearing. The Sound Level Meter was calibrated with a ‘‘standard acoustic calibrator’’ at 94 dB as prescribed in the instruction manual and mounted on the operating table beside the patient’s head, next to the ear. Measurements were data logged, labeled with serial numbers, and formatted into LAeq values (LAeq 5 long-term equivalent level with time constant applied). Peak sound levels Table 1. Surgery Categorized Into Two Major Categories Minor Surgery Biopsies Arthroscopies Minor bone fractures Removal of osteosynthetic
Major Surgery Traumas Amputations Cancer surgery Multi and major bone fractures
NOISE IN THE OR
(LPeak 5 peak sound pressure wave with no time constant applied) were also recorded. Patient Questionnaire Subjects filled out a questionnaire after being discharged from the recovery room. The patients were asked ‘‘How did you experience the sound level in the OR before you were anesthetized?’’ The response categories were based on a sevenpoint Likert scale with one as ‘‘very low’’ and seven as ‘‘very high.’’ This score was referred to as ‘‘the perception of noise score.’’ Subsequently, four detailed questions about the influence of the sound level followed, establishing if the sound level was perceived as annoying, disruptive, stressful, and noisy. The 13-item version of the SOC questionnaire (SOC13) was used to establish the patients’ SOC. This questionnaire contains 13 items and measures the degree to which the respondents view the world around them as comprehensible (five items), manageable (four items), and meaningful (four items).21 Responses to all items were scored on a seven-point Likert scale. The total SOC score was calculated by adding up the total sum score for all 13 questions. The total SOC score ranged from 13 to 91. A high score was indicative of a high SOC and a low score reflected a low SOC. The questionnaire has been shown to have a high degree of validity and reliability23 and has been translated into several languages. The Danish version, translated and retranslated by Due and Holstein,24 was used in this study. Statistical Analysis Based on the outcome ‘‘noise perception’’ and the assumption that 45% more acute patients than elective patients perceived noise, we calculated that 60 patients were required in each group (60 elective/60 acute) based on a power of 90% and a standardized difference of 0.9. The level of significance was set at P value lower than .05. The statistical analysis was performed in Stata/IC 12.1 statistics computer program for PC windows 2010 (StataCorp LP, College Station, TX). Univariate analyses were performed to determine the characteristics of patients and operations and to establish the distribution of the perception of noise score
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within the subgroups. Subgroup analyses were performed using Spearman’s rho test to establish correlation between the perception of noise score and the patient and operations characteristics. Cronbach’s alpha (a) was used to establish the degree of intercorrelation of items within the SOC scale and the five noise questions, respectively. Coefficients above 0.8 were regarded as acceptable. There is no ‘‘gold standard’’ for cut points within the SOC range to establish SOC as high, neutral, or low, and multiple ways of splitting SOC into subgroups have been used.23 To preserve the diversity within the scale, the SOC was analyzed and reported as a continuous variable using means and standard deviations (SDs), as this is the most common method of analyzing and reporting SOC used by the international researchers.23
Findings Characteristics of patients and operations are shown in Table 2. Findings are presented based on the three hypotheses: Table 2. Characteristics of Patients and Operations Characteristics of Patients Gender Men Female Age, y 18-39 40-59 , 60 Mean (SD) Previous anesthesia Yes No SOC, mean (SD) Characteristics of Operations Type Elective Acute (all) Acute (minor) Operation Minor Major LAeq, mean (SD) LPeak, mean (SD)
N (%) 62 (52) 58 (48) 32 (26.7) 50 (41.7) 38 (31.7) 50.3 (15.5) 105 (87.5) 15 (12.5) 67.5 (14.5) N (%) 60 (50) 60 (50) 36 (60) 96 (80) 24 (20) 61.3 (3.1) 78.4 (4.2)
SOC, sense of coherence; SD, standard deviation.
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Hypothesis 1
Hypothesis 3
Only 12 of the 120 patients (9 acute/3 elective) perceived the sound level in the OR to be very high (perception of noise score: 6-7). The intercorrelation between the five questions related to noise was very high (a 5 0.94). Patients with a high perception of noise score also scored high on the detailed questions, meaning that they also perceived the sound level as annoying, disruptive, stressful, and noisy.
As shown in Figure 2, acute patients perceived significantly more noise than elective patients (r 5 0.28/P , .01), despite the fact that acute patients were actually exposed to significantly lower noise levels than elective patients (mean LAeq: acute 5 60.2, elective 5 62.4; P , .01). All patients undergoing major surgery were acute. Adjusting for this, acute patients still perceived significantly more noise than elective patients (P 5 .04). Of the acute patients, those undergoing major surgery perceived more noise than patients undergoing minor surgery (r 5 0.25/P 5 .01), although patients undergoing major surgery were actually exposed to less noise than patients undergoing minor surgery (mean LAeq: minor surgery 5 61.8, major surgery 5 59.1; P #.01).
Hypothesis 2 The correlation between the perception of noise score and the patient and operations characteristics are shown in Figures 1 and 2. Figure 2 demonstrates the correlation between the actual noise levels to which the patients were exposed and their perception of noise. The correlation was very weak (LAeq: r 5 0.17/ P 5 .05, LPeak: r 5 0.19/P 5 .03), indicating that the actual noise levels in the OR do not greatly influence the patients’ perception of noise. Some of the patients who were exposed to the highest levels of noise did not perceive any noise, whereas several of the patients exposed to the lowest levels perceived a very high level of noise.
Hypothesis 4 Figure 1 illustrates that the patients’ SOC may influence their perception of noise (r 5 0.35/P , .01). Patients with a low SOC perceived more noise than those with a high SOC. About 92% of the patients who perceived sound levels as very high (perception of noise score: 6-7) had an SOC below 50. Among the patients who perceived the noise level
Figure 1. Correlation between perception of noise score and patients characteristics.
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Figure 2. Correlation between perception of noise score and operations characteristics.
as very high, mean SOC was 44.7 (SD 5 12.4), whereas mean SOC among the rest of the population was 70 (SD 5 12.4). Figure 1 also shows no correlation between patients’ perception of noise and the variables of sex, age, and previous anesthesia.
Discussion and Implications The results of this study indicate that noise in the OR in the preanesthesia period is not a problem for most patients. Our hypothesis was rejected, which of course is positive information for perianesthesia nurses and other staff working within the perianesthesia field. However, although it might only be a minority of patients who perceive noise, the results indicate that these patients actually perceive a very high level of noise, and furthermore, they also perceive the noise as annoying, disruptive, and stressful. Therefore, the problem of noise in the OR should not be ignored. Only a very weak correlation was found between actual noise levels and patients’ perception of noise (r , 0.2), confirming our hypothesis that there would be no correlation between actual noise levels and patients’ perception of noise. Although no correlation was found, awareness of noise levels and
the endeavor to keep them as low as possible coupled with efforts toward developing noise reduction procedures and routines are still important considerations for perianesthesia nurses. These results indicate that several variables other than the actual noise level impact the patients’ perception of noise in the OR before anesthesia. This is consistent with the definition of noise as a subjective experience dependent on the sound, context, and the individual. In this study, the characteristics of the sound are represented by measurements of LAeq and LPeak values. The context and the patient were represented by demographic variables and the SOC. The results indicate that being an acute patient is of significance in relation to the perception of noise. The correlation between these variables was highly significant, confirming our hypothesis and potentially explained by the fact that acute patients have not had the opportunity to prepare for the situation, which arises suddenly and unexpectedly. This can make them more vulnerable to stress stimuli such as noise. In the same way, patients undergoing major surgery will be more vulnerable to noise than those undergoing minor surgery because their situation is more serious and vital. This suggests that when caring for the patient in the preanesthesia period,
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perianesthesia nurses should be aware of the context of the situation. When caring for acute patients and patients undergoing major surgery, perianesthesia nurses should place particular focus on reducing unnecessary stress stimuli. The results of this study show that acute patients were actually exposed to significantly lower noise levels than elective patients, and patients undergoing major surgery were actually exposed to significantly lower noise levels than patients undergoing minor surgery. These findings suggest that perianesthesia nurses might already be aware of the importance of sparing acute patients and patients undergoing major surgery unnecessary noise as a stress stimulus. The results indicate that patients’ SOC influences their perception of noise and that patients with a low SOC might be particularly vulnerable to noise. This correlation was highly significant confirming the study hypothesis. However, this presents an issue that is difficult to act on. Perianesthesia nurses do not know when they are facing a patient with a low SOC. They know whether the patient is acute and/or is undergoing major surgery when receiving the patient in the OR, but the patient’s SOC is an unknown factor. Consequently, perianesthesia nurses cannot act on this fact. To be able to take action based on patients’ SOC, a way to screen patients to establish their SOC would have to be developed, a task that would be expensive and resource intensive. However, if patients’ SOC influences postoperative variables and impacts their postoperative recovery, such an exploration may be costeffective and should be investigated further.
aspects of the character of the sound are not fully investigated. The intercorrelation between the noise questions was very high (a 5 0.94). This indicates that we could have limited the number of noise questions used in the study. The intercorrelation within the SOC scale was also high (a 5 0.92). A simplified way of measuring SOC using only three questions (SOC3) has been developed by Lundberg and Peck.27 The reliability and validity of this short version has been shown to be questionable,28 and the SOC13 is still considered the shortest validated method to establish SOC.23 The SOC questions have an abstract dimension, as they refer to aspects of life in general. Subsequently, it is possible that some patients cannot or will not answer truthfully. The retrospective nature of the noise-related questions always has a tendency to produce more positive answers representing a higher degree of satisfaction than might have been the case at the time the event was experienced. Furthermore, the uncertainty regarding patients’ memory after anesthesia should be taken into account. Although the difference between acute and elective patients was highly significant, the difference was not as great as we expected. The validity of the results could therefore have been increased had the population been larger. On the other hand, because the results were so highly significant, we expect the results to be valid.
Conclusions Limitations We are aware that variables other than the ones investigated in this study can influence patients’ perception of noise in the OR. Not all variables related to the character of the sound were captured in this study. It is known that high, sharp sounds with a high pitch, high frequency, and intermittent appearance are more frequently perceived as noise.2,25 In addition, the unpredictability and controllability of the sound also influences whether the sound is perceived as noise, and sudden unpredictable sounds not controlled by the exposed person will more frequently be perceived as noise.22,26 Although Lpeak is included in this study, the
Perianesthesia nurses need to maintain their focus on keeping noise levels in the OR as low as possible. High levels of noise, and in particular high peak sounds, can be perceived as noise by patients. Although they are exposed to significantly lower noise levels, acute patients and patients with a low SOC (, 50) perceive significantly more noise than elective patients and patients with an SOC above 50. When caring for these patients, perianesthesia nurses should be particularly aware of reducing noise in the OR, as these patients might be more vulnerable to noise. The influence of SOC on postoperative variables related to patients’ recovery should be further investigated.
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References 1. Miller J. Effects of noise on people. J Acoust Soc Am. 1974; 56:729-764. 2. May DN. Handbook of Noise Assessment. Hartford, CT: Litton Educational Publishing, Inc.; 1978. 3. Shankar N, Malhotra KL, Ahuja S, et al. Noise pollution: A study of noise levels in the operating theatres of a general hospital during various surgical procedures. J Indian Med Assoc. 2001;99:244-247. 4. Hood LJ. Measurement of sound. Otolaryngol Clin North Am. 1991;24:233-251. 5. Shapior R, Baland T. Noise in the operating room. N Engl J Med. 1972;287:1236-1237. 6. WHO. Guidelines for Community Noise. Geneva, Switzerland: World Health Organization; 1999. 7. Hasfeldt D, Laerkner E, Birkelund R. Noise in the operating room—What do we know? A review of the literature. J Perianesth Nurs. 2010;25:380-386. 8. Lui EHC, Tan S-M. Patients’ perception of sound levels in the surgical suite. J Clin Anesth. 2000;12:298-302. 9. Leinonen T, Leino KH, Stahlberg M, et al. The quality of perioperative care: Development of a tool for the perceptions of patients. J Adv Nurs. 2001;35:294-306. 10. Nott MR, West PDB. Orthopaedic theatre noise: A potential hazard to patients. Anaesthesia. 2003;58:775-803. 11. Love H. Noise exposure in the orthopaedic operating theatre: A significant health hazard. ANZ J Surg. 2003;73: 836-838. 12. Christensen M. Do hospital personnel influence noise levels in an operating theatre and a postanaesthesia care unit? J Adv Periop Care. 2004;2:19-26. 13. Ullah R, Bailie N, Crowther S, et al. Noise exposure in orthopaedic practice: Potential health risk. J Laryngol Otol. 2004; 118:413-416. 14. Singh SA. Noise levels in the operating theatre environment. Natl Med J India. 2006;19:112-113. 15. Healey AN, Primus CP, Koutantji M. Quantifying distraction and interruption in urological surgery. Qual Saf Health Care. 2007;16:135-139.
16. Kracht JM, Busch-Vishniac IJ, West JE. Noise in the operating rooms of Johns Hopkins Hospital. J Acoust Soc Am. 2007; 121:2673-2680. 17. Tsiou C, Efthymiatos G, Koutantji M. Noise in the operating rooms of Greek hospitals. J Acoust Soc Am. 2008;123: 757-765. 18. Siverdeen Z, Ali A, Lakdawala AS, et al. Exposure to noise in the orthopaedic theatres—Do we need protection? Int J Clin Pract. 2008;62:1720-1722. 19. Stringer B, Haines TA, Oudyk JD. Noisiness in operating theatres: Nurses’ perceptions and potential difficulty communicating. J Perioper Pract. 2009;18:384-391. 20. Antonovsky A. Health, Stress and Coping: New perspectives on Mental and Physical Well-Being. San Francisco, CA: Jossey-Bass Inc., Publishers; 1979. 21. Antonovsky A. Unravelling the Mystery of Health—How People Manage Stress and Stay Well. San Francisco, CA: JosseyBass Inc., Publishers; 1987. 22. Hodge B, Thompson JF. Noise pollution in the operating theatre. Lancet. 1990;335:891-894. 23. Eriksson M. Unravelling The Mystery of Salutogenesis— The Evidence Base of the Salutogenic Research as Measures by Antonovsky’s Sense of Coherence Scale. Vasa, Finland: Folkh€alsan Research Centre, Health Promotion Research Programme; 2007. 24. Due EP, Holstein BE. Sense of coherence, socialgruppe og helbred i en dansk befolkningsundersøgelse. Ugeskr Læger. 1998;160:7424-7429. 25. Kahn DM. Measurement of sound. Otolaryngol Clin North Am. 1991;24:233-251. 26. Meyer-Falche A, Rack F, Eichwede F, et al. How noisy are anaesthesia and intensive care medicine? Quantification of the patients. Eur J Anaesthesiol. 1994;11:407-411. 27. Lundberg O, Peck MN. A simplified way of measuring sense of coherence. Eur J Public Health. 1995;5:56-59. 28. Schumann A, Hapke U, Meyer C, Rumpf H-J, John U. Measuring Sense of Coherence with only three items: A useful tool for population surveys. Br J Health Psychol. 2003;8:409-421.
Keywords: noise, operating room, patient perspective, sense of coherence, research, perianesthesia. Ó 2014 by American Society of PeriAnesthesia Nurses
Dorthe Hasfeldt, MSC, RNA, PhD student, Odense University Hospital, Department of Anesthesiology and Intensive Care, Denmark; Helle Terkildsen Maindal, PhD, MPH, Associate Professor, Aarhus University, Department of Public Health, Denmark; Palle Toft, PhD, MD, Professor, Odense University Hospital, Department of Anesthesiology and Intensive Care, Denmark; and Regner Birkelund, PhD, MSC, Associate Professor, University of Southern Denmark & Vejle Hospital, Denmark.
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Conflict of interest: None to report. Address correspondence to Dorthe Hasfeldt, Dept. Anesthetsiology and Intensive Care Sdr. boulevard 29, Intrance 5, 5000 Odense C, Denmark; e-mail address: d.hasfeldt@ hotmail.com. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.03.001
Journal of PeriAnesthesia Nursing, Vol 29, No 5 (October), 2014: pp 410-417
NOISE IN THE OR
NOISE IS A GENERAL stressor that can affect the cardiovascular system, resulting in increased blood pressure and heart rate, also known as the ‘‘startle effect.’’ This physical stress reaction provokes psychological stress responses.1-4 As such, noise in the operating room (OR) should be avoided as much as possible, particularly in the period between the patient’s arrival in the OR and until they are fully anesthetized. Patients are especially vulnerable to external stress stimuli during this period. Noise in the OR was first described in the 1970s, when Shapior and Baland5 registered noise levels in the OR and found that they equaled the level of noise on a freeway. They defined noise in the OR as ‘‘the third pollution,’’ equating noise with air and water pollution. In the Guidelines for Community Noise issued by the World Health Organization (WHO),6 it is pointed out that patients in hospital settings are particularly vulnerable to noise as their situation reduces their capacity to cope with stress. The WHO recommends that sound levels do not exceed 30 dB(A). Nevertheless, sound levels in ORs have been shown to be very high [average 50-75 dB(A), max peak 80-120 dB(A)] and in excess of the recommended levels.7 From our experience, noise is also a frequently discussed topic in clinical practice among OR staff. A literature review published in 20107 showed the topic of noise in the OR to be widely described with regards to noise levels in excess of the recommended levels,3,8-19 identifying noise sources as being related to equipment and staff behavior3,12,15,17 and identifying negative effects of noise on staff performances, mainly in relation to impaired communication.15,17,19 The review, however, revealed a lack of knowledge and understanding of the patient’s perspective. The literature on the patient’s perspective is sparse and contradictory.7 A previous study performed by Lui and Tan8 surprisingly revealed no correlation between patients’ perception of noise and the actual noise levels to which they were exposed. This could be explained by the fact that sound is perceived individually, and the degree to which a sound is perceived as noise not only depends on the character and the level of the sound but also on the person exposed to the sound and the context in which the sound is perceived. Patients in a particularly vulnerable situation, such as those facing acute surgery that they have not been able to
411
prepare themselves for owing to the sudden need for surgery, might be more sensitive to the sound in the environment than patients experiencing more planned and predictable situations. Some patients might be more sensitive because their capacity to cope with stress stimuli in general is limited. According to the theory of salutogenesis, developed by the medical sociologist Antonovsky,20,21 people with a low sense of coherence (SOC) are more vulnerable to stress stimuli because they have limited general resistance resources to cope with stressful situations. According to this theory, patients’ SOC might therefore influence their perceptions of noise in the OR.
Purpose The purpose of this study was to investigate if patients undergoing general anesthesia perceive noise in the OR in the period from their arrival until they are fully anesthetized, if there is any correlation between the actual noise levels to which patients are exposed and their perception of noise, and if subgroups particularly vulnerable to noise could be identified.
Hypotheses Based on a previous study conducted by Lui and Tan,8 we hypothesized that (1) approximately 50% of the patients undergoing general anesthesia for orthopaedic surgery perceive noise in the OR in the preanesthesia period, and (2) there is no correlation between the actual noise levels to which the patients are exposed and their perception of noise. We also hypothesized that (3) acute patients perceive more noise than elective patients, and owing to the context of their situation, they are more vulnerable to noise. Additionally, we hypothesized that (4) patients with a low SOC experience more noise than patients with a high SOC.
Design This cross-sectional study was performed using a mixed descriptive and analytical design. Three types of data were collected, namely demographic variables available on the anesthesia record, noise levels in the OR, and a post recovery patient questionnaire.
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Methods Population and Inclusion The study was approved by The Investigational Committee at Odense University Hospital in Denmark and The Danish Data Protection Agency (jour.no 2011-41-5948). Data collection were conducted in two hospitals in Southern Denmark, namely one large University hospital (Odense University Hospital) and one regional hospital (Kolding Hospital). As orthopaedic ORs have been shown to be the noisiest,3,17,22 mainly because of the instruments used in orthopaedic operations, data collection were conducted in orthopaedic surgery units. A total of 60 patients undergoing acute surgery (defined by the fact that the surgery is not planned because the need for surgery arises suddenly and unexpectedly) and 60 patients undergoing elective surgery were included. Inclusion took place consecutively when patients arrived at the surgery unit. Adult patients (aged $18 years) undergoing general anesthesia (total intravenous anesthesia) for orthopaedic surgery were included. Patients with a hearing impairment, including hearing aid users, were excluded as this could negatively influence the perception of noise and thereby bias the results. Patients who, on cognitive or linguistical ground, were considered not able to read, comprehend, or fill out the questionnaire were also excluded. Patients meeting the inclusion criteria were informed about the study; and if they agreed to participate, were consented. Study enrolment was continued until 120 completed questionnaires were returned. A total of 141 patients were eligible. Of these, 21 patients (11 elective and 10 acute) were excluded from the analysis because they did not complete the questionnaire for the following reasons: Five patients did not manage to complete the questionnaire owing to postoperative stress, pain, or nausea; Four patients were hindered by linguistic or cognitive difficulties; Four patients failed to answer all the questions; and Eight questionnaires were unaccounted for. Demographic Variables Demographic variables were obtained from the anesthesia record. The demographic variables
represented the minimum information perianesthesia staff has on a patient before the patient enters the OR and included:
Sex (male/female), Age, Type (acute/elective), Surgery (minor/major), and Previous general anesthesia (yes/no).
Both operation size and severity were taken into account in determining if the surgery was minor or major. All surgery related to cancer or other life-threatening vital conditions was defined as major (Table 1). Measurement of Noise Levels The actual noise levels to which patients were exposed in the OR were recorded. The sound level in the OR was measured from the time the patient entered the room until the anesthesia staff assessed the patient to be fully anesthetized, that is, when they demonstrated no ciliary reflex and no breathing. The measurements were performed with a ‘‘Voltcraft Datalogger 322 Sound Level Meter’’ (Conrad Electronic AG, Soloturn, Switzerland), which measures noise levels in decibels (dB) on a logarithmic scale. The sound level meter was set according to the WHO recommendations6 for sound level measurements, that is, it was set to measure dB(A) using a filter that corresponds to the human ear and to ‘‘fast response time’’ in which measurements are recorded every 0.125 s. This provides the most representative measurement of human hearing. The Sound Level Meter was calibrated with a ‘‘standard acoustic calibrator’’ at 94 dB as prescribed in the instruction manual and mounted on the operating table beside the patient’s head, next to the ear. Measurements were data logged, labeled with serial numbers, and formatted into LAeq values (LAeq 5 long-term equivalent level with time constant applied). Peak sound levels Table 1. Surgery Categorized Into Two Major Categories Minor Surgery Biopsies Arthroscopies Minor bone fractures Removal of osteosynthetic
Major Surgery Traumas Amputations Cancer surgery Multi and major bone fractures
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(LPeak 5 peak sound pressure wave with no time constant applied) were also recorded. Patient Questionnaire Subjects filled out a questionnaire after being discharged from the recovery room. The patients were asked ‘‘How did you experience the sound level in the OR before you were anesthetized?’’ The response categories were based on a sevenpoint Likert scale with one as ‘‘very low’’ and seven as ‘‘very high.’’ This score was referred to as ‘‘the perception of noise score.’’ Subsequently, four detailed questions about the influence of the sound level followed, establishing if the sound level was perceived as annoying, disruptive, stressful, and noisy. The 13-item version of the SOC questionnaire (SOC13) was used to establish the patients’ SOC. This questionnaire contains 13 items and measures the degree to which the respondents view the world around them as comprehensible (five items), manageable (four items), and meaningful (four items).21 Responses to all items were scored on a seven-point Likert scale. The total SOC score was calculated by adding up the total sum score for all 13 questions. The total SOC score ranged from 13 to 91. A high score was indicative of a high SOC and a low score reflected a low SOC. The questionnaire has been shown to have a high degree of validity and reliability23 and has been translated into several languages. The Danish version, translated and retranslated by Due and Holstein,24 was used in this study. Statistical Analysis Based on the outcome ‘‘noise perception’’ and the assumption that 45% more acute patients than elective patients perceived noise, we calculated that 60 patients were required in each group (60 elective/60 acute) based on a power of 90% and a standardized difference of 0.9. The level of significance was set at P value lower than .05. The statistical analysis was performed in Stata/IC 12.1 statistics computer program for PC windows 2010 (StataCorp LP, College Station, TX). Univariate analyses were performed to determine the characteristics of patients and operations and to establish the distribution of the perception of noise score
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within the subgroups. Subgroup analyses were performed using Spearman’s rho test to establish correlation between the perception of noise score and the patient and operations characteristics. Cronbach’s alpha (a) was used to establish the degree of intercorrelation of items within the SOC scale and the five noise questions, respectively. Coefficients above 0.8 were regarded as acceptable. There is no ‘‘gold standard’’ for cut points within the SOC range to establish SOC as high, neutral, or low, and multiple ways of splitting SOC into subgroups have been used.23 To preserve the diversity within the scale, the SOC was analyzed and reported as a continuous variable using means and standard deviations (SDs), as this is the most common method of analyzing and reporting SOC used by the international researchers.23
Findings Characteristics of patients and operations are shown in Table 2. Findings are presented based on the three hypotheses: Table 2. Characteristics of Patients and Operations Characteristics of Patients Gender Men Female Age, y 18-39 40-59 , 60 Mean (SD) Previous anesthesia Yes No SOC, mean (SD) Characteristics of Operations Type Elective Acute (all) Acute (minor) Operation Minor Major LAeq, mean (SD) LPeak, mean (SD)
N (%) 62 (52) 58 (48) 32 (26.7) 50 (41.7) 38 (31.7) 50.3 (15.5) 105 (87.5) 15 (12.5) 67.5 (14.5) N (%) 60 (50) 60 (50) 36 (60) 96 (80) 24 (20) 61.3 (3.1) 78.4 (4.2)
SOC, sense of coherence; SD, standard deviation.
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Hypothesis 1
Hypothesis 3
Only 12 of the 120 patients (9 acute/3 elective) perceived the sound level in the OR to be very high (perception of noise score: 6-7). The intercorrelation between the five questions related to noise was very high (a 5 0.94). Patients with a high perception of noise score also scored high on the detailed questions, meaning that they also perceived the sound level as annoying, disruptive, stressful, and noisy.
As shown in Figure 2, acute patients perceived significantly more noise than elective patients (r 5 0.28/P , .01), despite the fact that acute patients were actually exposed to significantly lower noise levels than elective patients (mean LAeq: acute 5 60.2, elective 5 62.4; P , .01). All patients undergoing major surgery were acute. Adjusting for this, acute patients still perceived significantly more noise than elective patients (P 5 .04). Of the acute patients, those undergoing major surgery perceived more noise than patients undergoing minor surgery (r 5 0.25/P 5 .01), although patients undergoing major surgery were actually exposed to less noise than patients undergoing minor surgery (mean LAeq: minor surgery 5 61.8, major surgery 5 59.1; P #.01).
Hypothesis 2 The correlation between the perception of noise score and the patient and operations characteristics are shown in Figures 1 and 2. Figure 2 demonstrates the correlation between the actual noise levels to which the patients were exposed and their perception of noise. The correlation was very weak (LAeq: r 5 0.17/ P 5 .05, LPeak: r 5 0.19/P 5 .03), indicating that the actual noise levels in the OR do not greatly influence the patients’ perception of noise. Some of the patients who were exposed to the highest levels of noise did not perceive any noise, whereas several of the patients exposed to the lowest levels perceived a very high level of noise.
Hypothesis 4 Figure 1 illustrates that the patients’ SOC may influence their perception of noise (r 5 0.35/P , .01). Patients with a low SOC perceived more noise than those with a high SOC. About 92% of the patients who perceived sound levels as very high (perception of noise score: 6-7) had an SOC below 50. Among the patients who perceived the noise level
Figure 1. Correlation between perception of noise score and patients characteristics.
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Figure 2. Correlation between perception of noise score and operations characteristics.
as very high, mean SOC was 44.7 (SD 5 12.4), whereas mean SOC among the rest of the population was 70 (SD 5 12.4). Figure 1 also shows no correlation between patients’ perception of noise and the variables of sex, age, and previous anesthesia.
Discussion and Implications The results of this study indicate that noise in the OR in the preanesthesia period is not a problem for most patients. Our hypothesis was rejected, which of course is positive information for perianesthesia nurses and other staff working within the perianesthesia field. However, although it might only be a minority of patients who perceive noise, the results indicate that these patients actually perceive a very high level of noise, and furthermore, they also perceive the noise as annoying, disruptive, and stressful. Therefore, the problem of noise in the OR should not be ignored. Only a very weak correlation was found between actual noise levels and patients’ perception of noise (r , 0.2), confirming our hypothesis that there would be no correlation between actual noise levels and patients’ perception of noise. Although no correlation was found, awareness of noise levels and
the endeavor to keep them as low as possible coupled with efforts toward developing noise reduction procedures and routines are still important considerations for perianesthesia nurses. These results indicate that several variables other than the actual noise level impact the patients’ perception of noise in the OR before anesthesia. This is consistent with the definition of noise as a subjective experience dependent on the sound, context, and the individual. In this study, the characteristics of the sound are represented by measurements of LAeq and LPeak values. The context and the patient were represented by demographic variables and the SOC. The results indicate that being an acute patient is of significance in relation to the perception of noise. The correlation between these variables was highly significant, confirming our hypothesis and potentially explained by the fact that acute patients have not had the opportunity to prepare for the situation, which arises suddenly and unexpectedly. This can make them more vulnerable to stress stimuli such as noise. In the same way, patients undergoing major surgery will be more vulnerable to noise than those undergoing minor surgery because their situation is more serious and vital. This suggests that when caring for the patient in the preanesthesia period,
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perianesthesia nurses should be aware of the context of the situation. When caring for acute patients and patients undergoing major surgery, perianesthesia nurses should place particular focus on reducing unnecessary stress stimuli. The results of this study show that acute patients were actually exposed to significantly lower noise levels than elective patients, and patients undergoing major surgery were actually exposed to significantly lower noise levels than patients undergoing minor surgery. These findings suggest that perianesthesia nurses might already be aware of the importance of sparing acute patients and patients undergoing major surgery unnecessary noise as a stress stimulus. The results indicate that patients’ SOC influences their perception of noise and that patients with a low SOC might be particularly vulnerable to noise. This correlation was highly significant confirming the study hypothesis. However, this presents an issue that is difficult to act on. Perianesthesia nurses do not know when they are facing a patient with a low SOC. They know whether the patient is acute and/or is undergoing major surgery when receiving the patient in the OR, but the patient’s SOC is an unknown factor. Consequently, perianesthesia nurses cannot act on this fact. To be able to take action based on patients’ SOC, a way to screen patients to establish their SOC would have to be developed, a task that would be expensive and resource intensive. However, if patients’ SOC influences postoperative variables and impacts their postoperative recovery, such an exploration may be costeffective and should be investigated further.
aspects of the character of the sound are not fully investigated. The intercorrelation between the noise questions was very high (a 5 0.94). This indicates that we could have limited the number of noise questions used in the study. The intercorrelation within the SOC scale was also high (a 5 0.92). A simplified way of measuring SOC using only three questions (SOC3) has been developed by Lundberg and Peck.27 The reliability and validity of this short version has been shown to be questionable,28 and the SOC13 is still considered the shortest validated method to establish SOC.23 The SOC questions have an abstract dimension, as they refer to aspects of life in general. Subsequently, it is possible that some patients cannot or will not answer truthfully. The retrospective nature of the noise-related questions always has a tendency to produce more positive answers representing a higher degree of satisfaction than might have been the case at the time the event was experienced. Furthermore, the uncertainty regarding patients’ memory after anesthesia should be taken into account. Although the difference between acute and elective patients was highly significant, the difference was not as great as we expected. The validity of the results could therefore have been increased had the population been larger. On the other hand, because the results were so highly significant, we expect the results to be valid.
Conclusions Limitations We are aware that variables other than the ones investigated in this study can influence patients’ perception of noise in the OR. Not all variables related to the character of the sound were captured in this study. It is known that high, sharp sounds with a high pitch, high frequency, and intermittent appearance are more frequently perceived as noise.2,25 In addition, the unpredictability and controllability of the sound also influences whether the sound is perceived as noise, and sudden unpredictable sounds not controlled by the exposed person will more frequently be perceived as noise.22,26 Although Lpeak is included in this study, the
Perianesthesia nurses need to maintain their focus on keeping noise levels in the OR as low as possible. High levels of noise, and in particular high peak sounds, can be perceived as noise by patients. Although they are exposed to significantly lower noise levels, acute patients and patients with a low SOC (, 50) perceive significantly more noise than elective patients and patients with an SOC above 50. When caring for these patients, perianesthesia nurses should be particularly aware of reducing noise in the OR, as these patients might be more vulnerable to noise. The influence of SOC on postoperative variables related to patients’ recovery should be further investigated.
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