Effects of guidelines implementation in a surgical intensive care unit to control nighttime light and noise levels

OBJECTIVE: Because of around-the-clock activities, environmental noise and light are among the many causes of sleep disturbance in an intensive care unit (ICU). The implementation of guidelines may potentially change behavior rules and improve sleep quality. DESIGN: A prospective interventional study, observing the effects of simple nighttime guidelines on light and noise levels in an ICU. SETTING: A modern surgical ICU, subdivided into six identical three-bed rooms. PATIENTS: Critically ill adult patients. INTERVENTION: Between two observation periods, five guidelines were implemented to decrease both light and noise during the night shift in the patient's room. MEASUREMENT: Light levels and noise levels were obtained using a luxmeter and a sound level meter [A-weighted decibels (dB) scale] and were monitored continuously from 11 pm to 5 am both before (period P1) and after (period P2) the implementation of guidelines. MAIN RESULTS: Similar patient's gravity and nursing workload scores were observed between P1 and P2. A low mean (<5 Lux) and maximal light level were measured during both P1 and P2. The implementation of guidelines lowered mean light disturbance intensity with a greater variability of light during P2. All noise levels were high and corresponded more to a quiet office for noise level equivalents and to a busy restaurant for peak noise levels during both P1 and P2. Guidelines decreased the noise level equivalent (P1, 51.3 dB; P2, 48.3 dB), peak noise level (P1, 74.9 dB; P2, 70.8 dB), and the number of acoustic identified alarms (P1, 22.1 dB; P2, 15.8 dB) during P2. CONCLUSION: The night light levels were low during both periods, and lowering the light levels induced a greater variation of light, which may impair sleep quality. All measured noise levels were high during both periods, which could contribute to sleep disturbance, and the implementation of guidelines significantly lowers some important noise levels. The background noise level was unchanged.     

Noise levels in a general intensive care unit: a descriptive study

The aim of this small-scale study was to measure, analyse and compare levels of acoustic noise, in a nine-bedded general intensive care unit (ICU). Measurements were undertaken using the Norsonic 116 sound level meter recording noise levels in the internationally agreed 'A' weighted scale. Noise level data were obtained and recorded at 5 min over 3 consecutive days. Results of noise level analysis indicated that mean noise levels within this clinical area was 56.42 dB(A), with acute spikes reaching 80 dB(A). The quietest noise level attained was that of 50 dB(A) during sporadic intervals throughout the 24-h period. Parametric testing using analysis of variance found a positive relationship (p or= 0.05). While the results of this study may seem self-evident in many respects, what it has highlighted is that the problem of excessive noise exposure within the ICU continues to go unabated. More concerning is that the prolonged effects of excessive noise exposure on patients and staff alike can have deleterious effect on the health and well-being of these individuals.     

Noise perception,heart rate and blood pressure in relation to aircraft noise in the vicinity of the Frankfurt airport

Summary The aim of this study was to evaluate subjective noise perception and objective parameters of circulation in the vicinity of the Frankfurt airport. Two areas were selected in which aircraft noise was the predominant source of noise (and was) created by planes induced by take off but not during landing. Data of residents living in the two areas were observed over a period of twelve weeks, one area being exposed to air traffic noise for three quarters of the given time, the other for one quarter of the time. Methods Fifty three volunteers (age 50–52 ± 15 y) monitored their blood pressure and heart rate over a period of three months by using an automatic device with digitized readings. They also protocolled their own subjective perception of noise and sleep quality. Thirty one probands were living West of the airport (West group) and were exposed to a nocturnal equivalent continuous air traffic noise level of L_eq(3) = 50 dB(A) outside, during flight direction 25 to the West. Twenty two probands were living East of the airport (East group) and were exposed to L_eq(3) = 50 dB (A) during flight direction 07 to the East. During the opposite flight directions air craft noise corresponded to L_eq(3) = 40 dB(A) in both areas. Frankfurt airport operates direction 25 for about 75% of the time on average and direction 07 for 25% of the time. Results The average blood pressure was significantly higher in the West group with higher noise exposure. Morning systolic blood pressure was 10 mmHg and diastolic pressure 8 mmHg higher in the West group. Throughout the observation period, the East group showed a parallel between daily changes in noise and subjective noise perception. In the West group such a parallel did not appear. This reaction was considered to be the consequence of the high noise exposure of the West group. Conclusions It is concluded that a population exposed to a nocturnal equivalent continuous air traffic noise level of L_eq(3) = 50 dB(A) for three quarters of a given time has a higher average blood pressure compared to a population exposed to the same equal energy noise level for only one quarter of the time. Within the East group a parallel between noise exposure and noise perception was observed, while in the West group this parallel did not appear. The difference is considered to be the consequence of higher noise stress levels in the West group. The data are in accordance with recent epidemiological studies and indicate that a nocturnal aircraft noise of L_eq(3) = 50 dB(A) can have negative effects on subjective noise perception and on objective parameters of circulation.     

Contribution of alarm noise to average sound pressure levels in the ICU: An observational cross-sectional study

ObjectivesTo explore sound levels, alarm frequencies and the association between alarms and sound levels.DesignA single center observational cross-sectional study.SettingFour intensive care units.Main outcome measuresContribution of alarms: red (life threatening), yellow (indicate excess of limits) and blue (technical) to sound pressure levels dB(A) at nursing stations.ResultsMean sound pressure levels differed significantly between day (56.1 ± 5.5), evening (55.1 ± 5.7) and night periods 53.6 ± 5.6; p < 0.01. 175,996 alarms were recorded of which 149,764 (85%) were yellow, 18,080 (10%) were red and 8,152 (5%) were blue. The mean sound levels without alarms (background) is 56.8 dB(A), with only red: 56.0 dB(A), only yellow: 55.6 dB(A), only blue: 56.0 dB(A) and mixed alarms: 56.3 dB(A). Yellow alarms (b = −0.93; 95% CI: −1.26 to −0.6; p < 0.001) were weakly but significantly associated with mean sound levels and lead to a slight decrease in noise level (1 dB), Red alarms (b = −0.3; 95% CI: −1.237 to 0.63; p = 0.52). The R Square of the model with all alarms was 0.01 (standard error of estimate, 6.9; p < 0.001).ConclusionsSound levels were high during all day-periods. Alarms exceeding limits occurred most frequently. However, the contribution of alarms to sound levels measured at the nursing station is clinically limited.     

An observational study of sound exposure in a single-room configured neonatal unit (SENSE study)

AimTo measure sound exposure in an Australian single-room configured, neonatal unit and compare findings to current sound level recommendations.MethodsSound meters were placed inside 51 internal environments (incubators or open cots), and within the surrounding environment of each occupied single room between September 15 and October 28, 2015. One-second incremental monitoring of decibels on an A-weighted scale (dBA), occurred over a minimum of 48 h.ResultsAll equivalent continuous sound pressure levels (L_eq) were significantly higher than the recommended 45 dBA for both incubators and open cots. Maximum sound levels (L_max) were significantly higher than the recommended 65 dBA, peaking at 126.7 dBA inside the incubator and 124.7 dBA inside the open cot. Incubators were observed to have a higher total percentage of time above 45 dBA than open cots for both day (99.84% vs. 75.59%) and night (98.66% vs. 59.56%).ConclusionSound levels exceeded the recommended maximum exposure levels outlined by the American Academy of Pediatrics (AAP). The long-term sequelae of adverse sensory exposure on preterm neurodevelopment remains unclear. Renewed attention on factors contributing to increased sound levels in neonatal units needs to be a clinical priority.     

水杨酸对C57BL/6小鼠耳蜗声损伤的作用

目的:探讨水杨酸对prestin正常表达小鼠耳蜗声损伤作用。方法:以出生18~30d的雄性C57BL/6小鼠为研究对象,分为3组(水杨酸 噪声;0.9%氯化钠 噪声;单纯水杨酸)。给予中心频率为8kHz强度为110d SPL的1/3倍频程噪声暴露3h。以听诱发脑干反应、扫描和透射电镜方法比较有、无水杨酸干预情况下小鼠耳蜗听力及形态损伤程度。用荧光定量PCR方法比较两组小鼠耳蜗prestin mRNA总量的变化情况。结果:噪声暴露后第1天,水杨酸干预组的ABR阈移较0.9%氯化钠组减少27dBSPL;第10天减少17dBSPL。水杨酸提前干预使耳蜗的噪声损伤后扫描电镜和透射电镜上外毛细胞及支持细胞损伤减轻。在噪声暴露后第10天,水杨酸组prestin mRNA总量较0.9%氯化钠组及噪声暴露前均升高。结论:水杨酸提前干预可以显著减轻prestin正常表达小鼠耳蜗的噪声损伤;水杨酸干预可能会导致外毛细胞马达蛋白prestin表达上升。     

对侧抑制效应对强声所致耳蜗听力功能降低的影响

背景耳声发射是了解听觉功能受损情况的敏感测量方法,而对侧抑制可改变耳蜗的功能状态. 目的了解对侧抑制效应对噪声暴露后畸变产物耳声发射( DPOAE) 听力图幅值的影响. 设计自身对照的前瞻性研究. 地点和对象在同济医科大学协和医院完成,耳科正常人 20例 40 耳,男 9例,女 11例. 干预对受试者以宽带噪声为对侧抑制声 (60 dB SPL), 105 dB SPL 2 kHz窄带噪声暴露 10 min,以 L1=70 dB SPL,L2=60 dB SPL,f2/f1=1.21的初始音进行 DPOAE听力图测试观察. 主要观察指标 DPOAE幅值. 结果噪声暴露可引起暴露声以上各频率测量点的 DPOAE 2f1-f2反应幅值显著性降低 (t=5.468,4.984,4.796,5.966,3.546,P均 < 0.05),以暴露声半倍频 f2频率处 (f2=3kHz)降低最为显著 (t=4.984,P=0.000 02). 而对侧抑制效应主要表现在 2 kHz 测量点,使此处幅值显著降低 (t=3.148,P=0.003).暴露后存在对侧抑制与否对 2～ 6 kHz f2频率处的 2f1-f2幅值改变具有明显影响( t=5.452,4.037,4.798,5.964,3.564,P 均 < 0.001). 结论 DPOAE听力图测试具有较好的频率特异性和高度敏感性,能特异而敏感地反映出对侧抑制和噪声暴露的效应.对侧抑制效应明显增加了 DPOAE测量对强声所引起的耳蜗功能降低的敏感性.     

Effects of intensive care unit noise on patients: a study on coronary artery bypass graft surgery patients

Aims and objectives. The aim of this study was to measure the noise levels in specific locations of an intensive care unit and determine the disturbance levels of patients owing to noise. Background. Studies have shown that hospital noise is a potential stressor for patients. Noise levels measured in the intensive care unit are mostly far beyond the recommended standards for hospitals, and generally measured around 60–70 dB (A). Although there are a few studies on noise levels in the intensive care unit, no study could be found that compares 24‐hour intensive care unit noise measurement data at several locations of intensive care unit. Methods. The study was conducted with 35 coronary artery bypass graft surgery patients. The intensive care unit noise level was measured by using Bruel & Kjaer 2144 Model Frequency Analyzer next to the bed of each patient. A patient's disturbance owing to the intensive care unit noise was questioned. Results. Noise levels ranged between 49 and 89 dB (A) with a mean of 65 dB (A). Peak noise levels were measured as high as 89 dB (A). The noise levels measured at different locations in the intensive care unit did not differ significantly. Noises created by other patients, those who were admitted from emergency room and operating room into intensive care unit, monitor alarms, conversations among staff were the most disturbing noise sources for patients. Conclusion. The patients who were located in the bed which was closer to the nurses' station were more affected by the intensive care unit noise than other patients. Having a previous intensive care unit experience also affected the patients’ disturbance levels owing to noise. Relevance to clinical practice. Nurses are in key positions where they can identify physical, psychological and social stressors that affect patients during their hospital stay. Staff education, planned nursing activities and proper design of intensive care unit may help combat this overlooked problem.     

西洛他唑对强噪声所致豚鼠耳蜗血流及听阈偏移的影响

目的:探讨在强噪声条件下,磷酸二酯-3A(phosphodiasterase-3A,PDE3A)特异性抑制剂西洛他唑(cilostazol)对豚鼠耳蜗血流及听阈偏移的影响。方法:将40只雄性豚鼠随机分为4组(每组10只):对照组、无噪声给药组、强噪声不给药组,强噪声给药组。强噪声组给予4 KHz的倍频窄带噪声(105 dB SPL)处理13 h。处理后立即腹腔注射西洛他唑(10 mg/kg),分别测定处理后各组动物的耳蜗血流速度及ABR阈值。结果:与对照组相比较,强噪声不给药组的血流速度在处理后60、90、120 min时均显著性下降(P<0.01);与强噪声不给药组比较,强噪声给药组的血流速度在处理后30、60、90、120 min时均显著性增高(P<0.05)。与对照组相比较,强噪声不给药组在处理后ABR阈值显著性高于对照组(P<0.05);与强噪声组不给药组相比较,强噪声组给药组ABR阈值要显著性降低(P<0.01)。结论:西洛他唑能有效改善耳蜗的血流状况及恢复强噪声所致豚鼠的听阈偏移     

Effects of underwater sound exposure on neurological function and brain histology

To evaluate the safety of sonar exposure from a neurological perspective, the vulnerability of the central nervous system to underwater exposure with high-intensity, low-frequency sound (HI-LFS) was experimentally examined. Physiological, behavioral and histological parameters were measured in anesthetized, ventilated rats exposed to brief (5 min), underwater HI-LFS. Exposure to 180 dB sound pressure level (SPL) re 1 microPa at 150 Hz (n = 9) did not alter acute cardiovascular physiology (arterial blood pH, pO(2), pCO(2), heart rate, or mean arterial blood pressure) from that found in controls (n = 11). Rats exposed to either 180 dB SPL re 1 microPa at 150 Hz (n = 12) or 194 dB SPL re 1 microPa at 250 Hz (n = 12) exhibited normal cognitive function at 8 and 9 days after sound exposure. Evaluation of neurological motor function revealed a minor deficit 7 days after 180 dB SPL/150 Hz exposure that resolved by 14 days, and no deficits after 194 dB SPL/250 Hz exposure. No overt histological damage was detected in any group. These data suggest that underwater HI-LFS exposure may cause transient, mild motor dysfunction.     

Noise exposure during noninvasive ventilation with a helmet,a nasal mask,and a facial mask

Objective To assess noise exposure during noninvasive ventilation (NIV) with different types of interface (helmet, nasal, and facial masks).Subjects and methods Ten naive healthy volunteers underwent NIV at pressure support levels of 10 and 15 cmH₂O with: (a) helmet, (b) helmet equipped with HME filters at the junctions between the helmet and the inspiratory and expiratory branches of the respiratory circuit, (c) nasal mask, and (d) facial mask. Noise intensity was assessed with a sound level meter by placing a microphone near the right ear. Noise intensity and degree of discomfort were also assessed subjectively with a visual analogue scale.Results Inside the helmet noise exceeded 100 dB. Noise intensity was poorly affected by pressure support level and unaffected by the presence of HME filters. During NIV with nasal or facial masks the noise did not exceed 70 dB (i.e., noise was not louder than the usual noise background in ICU). Subjective evaluation of noise intensity mirrored objective measurements; however, the presence of HME filters was associated with the feeling of less noise inside the helmet. The discomfort associated with the helmet did not significantly differ from that associated with the masks.Conclusions NIV helmet is associated with significantly greater noise than nasal and facial masks, but is as comfortable as masks, at least in the short term. Medium- and long-term exposure to loud noise may potentially impair ear function and increase the patients discomfort.     

Low melatonin excretion during mechanical ventilation in the intensive care unit

Biochemical markers for the circadian rhythm were studied in patients treated at the ICU (intensive care unit) of two regional hospitals. A normal rhythm is characterized by a relatively higher melatonin and a lower cortisol excretion at night. Disturbances affect sleep, mood and cognitive performance. All urine excreted between 07:00 and 22:00 hours (day) and between 22:00 and 07:00 hours (night) was collected and sampled throughout the entire ICU period (median, 10 days) in 16 patients for the excretion of 6-SMT (6-sulphatoxymelatonin), which is a metabolite of melatonin, and free cortisol. The overall excretion of 6-SMT was slightly lower and the cortisol excretion higher than reported for healthy reference populations. Mechanical ventilation was associated with a markedly lower 6-SMT excretion (median, 198 ng/h) compared with periods without such help (555 ng/h; P<0.0001), whereas infusion of adrenergic drugs increased the 6-SMT excretion (P<0.01). Five patients (31%) showed a virtually absent melatonin excretion for 24 h or more. The diurnal rhythms were consistently or periodically disturbed in 65% and 75% of the patients. These alterations cannot be explained by excessive exposure to light at night. In conclusion, there was hyposecretion of melatonin during mechanical ventilation, an overall high cortisol excretion and a disturbed diurnal rhythm of both of these hormones in most patients treated in two ICU departments.     

Changes in muscle tissue oxygenation during stagnant ischemia in septic patients

Objective To determine changes in the rate of thenar muscles tissue deoxygenation during stagnant ischemia in patients with severe sepsis and septic shock.Design and setting Prospective observational study in the medical ICU of a general hospital.Patients and participants Consecutive patients admitted to ICU with septic shock (n=6), severe sepsis (n=6), localized infection (n=3), and healthy volunteers (n=15).Interventions Upper limb ischemia was induced by rapid automatic pneumatic cuff inflation around upper arm.Measurements and results Thenar muscle tissue oxygen saturation (StO₂) was measured continuously by near-infrared spectroscopy before and during upper limb ischemia. StO₂ before intervention was comparable in patients with septic shock, severe sepsis, or localized infection and healthy volunteers (89 [65, 92]% vs. 82 [72, 91]% vs. 87 [85, 92]% vs. 83 [79, 93]%, respectively; p>0.1). The rate of StO₂ decrease during stagnant ischemia after initial hemodynamic stabilization was slower in septic shock patients than in those with severe sepsis or localized infection and in controls (–7.0 [–3.6, –11.0] %/min vs. –10.4 [–7.8, –13.3] %/min vs. –19.5 [–12.3, –23.3] vs. –37.4 [–27.3, –56.2] %/min, respectively; p=0.041). At ICU discharge the rate of StO₂ decrease did not differ between the septic shock, severe sepsis, and localized infection groups (–17.0 [–9.3, –28.9] %/min vs. –19.9 [–13.3, –23.6] %/min vs. –23.1 [–20.7, –26.2] %/min, respectively), but remained slower than in controls (p<0.01). The rate of StO₂ decrease was correlated with Sequential Organ Failure Assessment (SOFA) score (r=0.739, p<0.001).Conclusions After hemodynamic stabilization thenar muscle tissue oxygen saturation during stagnant ischemia decreases slower in septic shock patients than in patients with severe sepsis or localized infection and in healthy volunteers. During ICU stay and improvement of sepsis the muscle tissue deoxygenation rate increases in survivors of both septic shock and severe sepsis and was correlated with SOFA score.     

重症医学科护士仪器设备报警疲劳现状及其影响因素分析

目的探讨重症医学科(ICU)护士仪器设备报警疲劳现状及其影响因素分析。方法2020年1月-6月应用一般资料调查问卷、仪器设备报警管理问卷、临床仪器报警疲劳量表对3所三甲医院共125名ICU护士进行调查,采用多元回归分析影响ICU护士仪器设备报警疲劳的相关因素。结果ICU护士仪器报警疲劳总评分为(19.25±3.78)分,处于较高水平。经多元回归分析结果显示,大专学历、科室为综合科室、职称为护士、值夜班、带病工作是影响ICU护士对仪器报警疲劳的主要因素(P<0.05),而护士设备报警功能认知能力及设备功能管理能力是保护因素(P<0.05)。结论ICU护士对仪器设备报警疲劳较明显,因此护理管理者应强化护士仪器设备报警安全意识,提高护士仪器设备管理能力,降低护士仪器设备报警疲劳感。     

Characterisation of sleep in intensive care using 24-hour polysomnography: an observational study

Introduction

Many intensive care patients experience sleep disruption potentially related to noise, light and treatment interventions. The purpose of this study was to characterise, in terms of quantity and quality, the sleep of intensive care patients, taking into account the impact of environmental factors.

Methods

This observational study was conducted in the adult ICU of a tertiary referral hospital in Australia, enrolling 57 patients. Polysomnography (PSG) was performed over a 24-hour period to assess the quantity (total sleep time: hh:mm) and quality (percentage per stage, duration of sleep episode) of patients'' sleep while in ICU. Rechtschaffen and Kales criteria were used to categorise sleep. Interrater checks were performed. Sound pressure and illuminance levels and care events were simultaneously recorded. Patients reported on their sleep quality in ICU using the Richards Campbell Sleep Questionnaire and the Sleep in Intensive Care Questionnaire. Data were summarised using frequencies and proportions or measures of central tendency and dispersion as appropriate and Cohen''s Kappa statistic was used for interrater reliability of the sleep data analysis.

Results

Patients'' median total sleep time was 05:00 (IQR: 02:52 to 07:14). The majority of sleep was stage 1 and 2 (medians: 19 and 73%) with scant slow wave and REM sleep. The median duration of sleep without waking was 00:03. Sound levels were high (mean Leq 53.95 dB(A) during the day and 50.20 dB(A) at night) and illuminance levels were appropriate at night (median <2 lux) but low during the day (median: 74.20 lux). There was a median 1.7 care events/h. Patients'' mean self-reported sleep quality was poor. Interrater reliability of sleep staging was highest for slow wave sleep and lowest for stage 1 sleep.

Conclusions

The quantity and quality of sleep in intensive care patients are poor and may be related to noise, critical illness itself and treatment events that disturb sleep. The study highlights the challenge of quantifying sleep in the critical care setting and the need for alternative methods of measuring sleep. The results suggest that a sound reduction program is required and other interventions to improve clinical practices to promote sleep in intensive care patients.

Trial registration

Australian New Zealand clinical trial registry (http://www.anzctr.org.au/): ACTRN12610000688088.     

Healthcare-related costs in very elderly intensive care patients

Introduction

The long-term outcome of “very old intensive care unit patients” (VOPs; ≥?80 years) is often disappointing. Little is known about the healthcare costs of these VOPs in comparison to younger ICU patients and the very elderly in the general population not admitted to the ICU.

Methods

Data from a national health insurance claims database and a national quality registry for ICUs were combined. Costs of VOPs admitted to the ICU in 2013 were compared with costs of younger ICU patients (two groups, respectively 18–65 and 65–80 years old) and a matched control group of very elderly subjects who were not admitted to the ICU. We compared median costs and median costs per day alive in the year before ICU admission (2012), the year of ICU admission (2013) and the year after ICU admission (2014).

Results

A total of 9272 VOPs were included and compared to three equally sized study groups. Median costs for VOPs in 2012, 2013 and 2014 (€5944, €35,653 and €12,565) are higher compared to the ICU 18–65 population (€3022, €30,223 and €5052, all p?<?0.001) and the very elderly control population (€3590, €4238 and €4723, all p?<?0.001). Compared to the ICU 65–80 population, costs of VOPs are higher in the year before and after ICU admission (€4323 and €6750, both p?<?0.001), but not in the year of ICU admission (€34,448, p?=?0.950). The median healthcare costs per day alive in the year before, the year of and the year after ICU admission are all higher for VOPs than for the other groups (p?<?0.001).

Conclusions

VOPs required more healthcare resources in the year before, the year of and the year after ICU admission compared to younger ICU patients and the very elderly control population, except compared to the ICU 65–80 population in the year of ICU admission. Healthcare costs per day alive, however, are substantially higher for VOPs than for all other study groups in all three studied years.

     

An Effective, Economical Method of Reducing Environmental Noise in the Vivarium

High levels of ambient noise can have detrimental effects on laboratory animal wellbeing and may affect experimental results. In addition, excessive noise can reduce technician comfort and performance. This study was performed to determine whether inexpensive, passive acoustic noise abatement measures could meaningfully reduce noise levels. Sound level measurements for various activities were obtained in the incoming processing room for pigs before and after installing gypsum acoustic paneling, covering metal-to-metal contact points with strips of adhesive-backed rubber, and replacing hard plastic wheels on transport carts with neoprene wheels. The modifications reduced the overall average noise level by 8.1 dB. Average noise levels for each activity were all less than 85 dB after the modifications. Average noise levels can be reduced effectively and economically with passive abatement methods. Intermittent spikes in noise are more difficult to control and may require attention to the individual activity.Abbreviation: SPL, sound pressure levelAs noted in a special issue of this journal several years ago,¹⁵ environmental noise can affect virtually every system of the body, affecting the wellbeing of both the laboratory animals and the vivarium staff. Although veterinarians and technicians, who spend more time in the animal facilities, may recognize noise problems, frequently investigators are unaware of noise levels or how noise can affect experimental results.¹We regularly process incoming pigs in a hogwash that was thought to be one of the noisiest rooms in the vivarium. Added to the stress of being transferred to a new facility, background noise, sounds from the movement of equipment, and vocalization of the animals themselves can compound the existing stress level of the pigs, disturbing their homeostasis and overall health. Not only is the quality of life of the animal diminished by noise, later experimental findings can be affected negatively.^8,12,14 Physiologic changes arising from the stress of loud ambient noise can interfere with the experimental measurements, thus confounding the results of the study.Short-term exposure of pigs to noise levels in the range of 80 to 97 dB has been observed to increase ambulation scores in proportion to level and frequency.¹⁴ Noise levels over 80 dB have been found to cause behavioral changes in pigs, and the combination of noise and elevated ambient ammonia levels resulted in altered nasal and ocular discharge.^11,13 Although moderate levels of noise (less than 80 dB) had no apparent effect on pigs in one study, higher levels (95 dB) produced an increase in anxiety.² Pigs repeatedly exposed to broad-band noise (2 h, 90 dB) displayed markedly increased levels of the stress-related hormones ACTH and cortisol, with reduced social interaction and growth.^8,12 Noise levels in the range of 92 to 102 dB led to infertility, abortion, and decreased growth rate.¹⁷ Acute exposure of pigs to high levels of noise (120 dB) resulted in increased corticosteroid levels, whereas more prolonged exposure led to an increase in catecholamines.^,9,10Humans and pigs have similar hearing ranges. The average human hearing range extends from 31 Hz to 17.6 kHz at 60 dB sound pressure level (SPL), with the range of highest sensitivity at 10 dB SPL being 250 Hz to 8.1 kHz.⁴ Pigs have a slightly wider overall range, from 42 Hz to 40.5 kHz at 60 dB SPL and a region of high sensitivity at 10 dB SPL from 250 Hz to 16 kHz.⁵ Reduction of the overall noise within these overlapping audio ranges is likely to benefit both pigs and humans.In the current study, we sought to determine whether relatively inexpensive, passive noise-abatement measures could reduce environmental noise in the initial processing room for pigs in the entrance portion of the vivarium. We felt that reducing noise, especially decreasing average levels below 85 dB, would improve environmental conditions for both for the animals and the staff.     

An investigation of sound levels on intensive care units with reference to the WHO guidelines

Introduction

Patients in intensive care units (ICUs) suffer from sleep deprivation arising from nursing interventions and ambient noise. This may exacerbate confusion and ICU-related delirium. The World Health Organization (WHO) suggests that average hospital sound levels should not exceed 35 dB with a maximum of 40 dB overnight. We monitored five ICUs to check compliance with these guidelines.

Methods

Sound levels were recorded in five adult ICUs in the UK. Two sound level monitors recorded concurrently for 24 hours at the ICU central stations and adjacent to patients. Sample values to determine levels generated by equipment and external noise were also recorded in an empty ICU side room.

Results

Average sound levels always exceeded 45 dBA and for 50% of the time exceeded between 52 and 59 dBA in individual ICUs. There was diurnal variation with values decreasing after evening handovers to an overnight average minimum of 51 dBA at 4 AM. Peaks above 85 dBA occurred at all sites, up to 16 times per hour overnight and more frequently during the day. WHO guidelines on sound levels could be only achieved in a side room by switching all equipment off.

Conclusion

All ICUs had sound levels greater than WHO recommendations, but the WHO recommended levels are so low they are not achievable in an ICU. Levels adjacent to patients are higher than those recorded at central stations. Unit-wide noise reduction programmes or mechanical means of isolating patients from ambient noise, such as earplugs, should be considered.     

A PET Study of Visuomotor Learning under Optical Rotation

We measured the regional cerebral blood flow (rCBF) in six healthy volunteers with PET (positron emission tomography) and H¹⁵₂O to identify the areas of the human brain involved in sensorimotor learning. The learning task was visually guided reaching with sensorimotor discrepancy caused by optical rotation. PET measurements were performed in the early and late stages of the adaptation to the sensorimotor perturbation. Control measurements were obtained during an eye movement task and a reaching task without optical rotation. The rCBF data of each learning stage were compared to those of both control conditions. During the early stage, rCBF increases were detected in the rostral premotor cortex bilaterally, the posterior part of the left superior parietal lobule (SPL), and the right SPL including the intraparietal sulcus (IPS). During the late stage, rCBF increases were detected in the left caudal premotor area, the left supplementary motor area proper, the left SPL, the right SPL including the IPS, and the right postcentral sulcus extending to the inferior parietal lobule. These results reveal that sensorimotor learning accompanies changes in the recruited cortical areas during different stages of the adaptation, reflecting the different functional roles of each area for different components of adaptation, from learning of new sensorimotor coordination to retention or retrieval of acquired coordination.