The Effect of Noise and Light on Sedation in Critical Care Patients. A Cross-Sectional Study of Critical Care Nurses in Three Intensive Care Units in Norway

Introduction

Sleep in patients in intensive care units (ICUs) is severely disturbed, and can be characterised as short, light, and fragmented (1). International guidelines for pain, sedation, delirium, immobility, and sleep (PADIS) recommend analgosedation in critically ill patients. Analgosedation is a strategy where patient pain and discomfort are managed first, before providing sedative therapy (2,3). Consequently, patients might be more awake during their ICU stay (4).

Several studies have identified that noise and light are factors that interfere with patients’ sleep in ICUs (5–7). In addition, ICU survivors have reported a frequent recall of noise during their ICU stay (8). Sleeping disorders has a significant pathophysiological effect on critical care patients, because lack of sleep contributes to inhibiting the recovery of health, and is a predisposing factor for delirium, which is associated with increased mortality (2,9). A bundle concept of non-pharmacological strategies with comfort and patient-centred care, which includes control of the environmental factors such as noise and light, has therefore become a mainstay of ICU care (10–12).

Critical care patients are surrounded by high-tech equipment that supports and monitors vital signs (13). To avoid interrupted sleep, the World Health Organization recommends a sound level of below 35–40 decibels (14). However, high levels of sound are frequently reported in ICUs (5,6). Technical equipment is also a source of light in ICU environments, and light at night is a common cause of sleep interruptions (7,15). Consequently, the patient’s circadian rhythms are misaligned and disrupted, which in turn may interfere with their critical condition (9,16). To handle different sources of noise and light in the ICU, further studies investigating sources of noise and light in ICUs are needed.

Critical care patients are subjected to both noise and light during their ICU stay, which makes it challenging for the critical care nurse (CCN) to facilitate sleep for the patients. The PADIS guidelines recommend a non-pharmacological intervention to facilitate sleep (2,3). However, this might not always be feasible or appropriate in all clinical settings (17,18). CCNs assess the patient’s condition and facilitate recovery, including deep natural sleep. In several countries, CCNs have a delegated mandate to give medication on indication, and studies indicate that CCNs frequently use hypnotics to facilitate sleep (19,20). However, sedatives are not recommended, and sedatives might even potentiate the challenge of achieving deep, natural sleep (2,3). There remains a lack of studies demonstrating sedation practice when a patient’s sleep is disturbed by noise or light. The aims of this study were: 1) to evaluate the CCNs’ perceptions regarding sources of noise and light in the ICU, and 2) to identify factors associated with critical care patients’ need for sedation when their sleep is disturbed by noise or light.

Methods

This study is reported in adherence with the STROBE statements for reporting cross-sectional studies (21).

Results

Discussion

To our knowledge, this is the first study demonstrating an association between CCNs’ use of sedatives to induce sleep for ICU patients as compensation for environmental factors such as noise and light during the night. We found that a large majority of the responding CCNs agreed or strongly agreed that noise and light disturbed sleep at night for the ICU patients. Furthermore, we identified a difference in CCNs’ perceptions across three ICUs.

Our findings showed a relationship between the CCNs’ awareness of noise and light and the need for sedatives to induce sleep. This indicates that, on the personal level, CCNs might use sedative medications to compensate for disturbing environmental factors, which may result in higher dosages, leading to potentially negative consequences such as increased time on mechanical ventilation, longer ICU stay, higher mortality, greater cognitive decline and more psychological complications (28–30).

One study indicates that people have different sensitivity to what they perceive as noise, which makes people react differently to the same sound level (31). This is more a personality trait that is influenced by individual perspectives and behaviours that contribute to the decision-making process of choices. Consequently, CCNs may have different responses to the same sound level, which can lead to a mismatch between the nurse’s interpretation of symptoms and the patient’s perceived symptoms (32,33). One study suggests that nurses do not assess a patient’s discomfort systematically, resulting in CCNs individually interpreting what is in the best interest of the patient (17). In contrast, a patient’s self-reporting is the gold standard when it comes to both symptoms and discomfort. Inconforts des patients de reanimation (IPREA) is a recommended and validated questionnaire where patients self-report 18 ICU-related discomforts, including light and noise (34–37). Using the IPREA questionnaire to assess comfort in ICU patients, to facilitate the inclusion of local interventions to reduce discomforts, is shown to reduce both self-perceived discomfort and post-traumatic stress disorder (35,38). In the future, the use of self-reported questionnaires, such as IPREA, should be used to improve unit-specific problems such as noise and light.

On a system level, we found a significant difference between the ICUs. This might indicate different cultures for both awareness of disturbing environmental factors and for sedation practice. However, CCNs from both university and regional hospitals were included in this study, which might represent some important dissimilarities between the units, for example related to patient characteristics (e.g., severity of illness) or the construction of the ICUs (e.g., units with single rooms may provide lower levels of noise and light, versus units with shared rooms). A recently published paper indicated that analgosedation is implemented in different degrees across ICUs in Norway (22). A review identified that sedatives were mainly administered as continuous infusions, added with boluses as needed (3). However, one study reported a significant differences across ICUs regarding the use of continuous infusion versus bolus dosages of sedatives (22). A multicentre study did not find a significant difference in clinical outcomes between no sedation and lighter sedation practice (39). In addition, there is an increased trend of using dexmedetomidine, clonidine, and remifentanil, and a decreased use of benzodiazepines, in the past 20 years. There is therefore still a need for more and stronger evidence for clinical outcomes after implementing the PADIS guidelines (3,40,41).

The CCNs perceived that there was a high level of noise in their ICUs, and the sources of noise were most frequently alarms or nurses talking. These results are in accordance with other studies (32,42). Measures of the sound level in ICUs are shown to be high throughout the day, especially during oral nursing reports (43). Another study showed that alarm limits are seldom set at an appropriate level (44). It therefore seems to be easy for the CCNs to ignore alarm sounds, which results in sound levels becoming a burden for patients, making it difficult for them to sleep and rest. The association between disturbing environmental factors and the development of delirium is well-known, which in turn might result in adverse outcomes and even increase the mortality (45,46). One study suggests that more reliable alarms may increase the precise response of the CCNs, and thereby both increase patient safety and reduce noise pollution (47).

A large majority of the responding CCNs agreed or strongly agreed that there was a difference in light during day versus night, which indicates a strategy of circadian rhythm in their ICU. However, there were variations between units, and at one unit fewer CCN reported a systematic use of difference between night and day. To maintain normality and to facilitate sleep for the ICU patients, it is recommended to implement a circadian rhythm in the ICU (2,3). Conflicts might therefore arise between what is in the best interest of the patient and what is in the best interest of the nurse. The shift work schedule and night workload for nurses, in addition to factors that enable nurses to make good observations at night, may require light in the patient’s room (48). This conflict should be discussed in the ICUs to find a balance between good working conditions for the CCN and optimal comfort for the patient.

Several studies show that the implementation of guidelines regarding the management of pain, sedation, and delirium has been challenging in clinical practice, however, quality improvement has been shown to have a good effect (49–52). Factors including implementation planning, training, effective documentation, and reflections are identified as promoting implementation (53,54). A multimodal approach, such as comfort and patient-centred care without excessive sedation (eCASH), has also been proposed (11). In addition to interventions such as pain-relief first and the comprehensive use of spontaneous mechanical ventilation settings, it is important to highlight nursing actions – for example, reducing noise and regulating light in accordance with the circadian rhythm (55).

Strengths and limitations

A strength in this study was a high response rate, and respondents were included from three different ICUs at three different hospitals, thereby making the findings generalisable or at least transferable to other ICUs in Norway. There were few missing values in the study, which strengthens the face validity. It is a strength that the questionnaire was pilot-tested before start-up. Another strength is that the participants in the study were clinicians who work closely with ICU patients, which strengthens the content validity of the study.

The questionnaire used in this study has not been psychometric-tested for reliability and validity, which is the main limitation in the study. The questionnaire has been constructed based on relevant literature and discussions with experts, but not using a validated questionnaire might influence the content validity in the study. Data used in this study is from 2015–2016, which might affect the answers, as guidelines for sedation practice has changed the last years. Another weakness is that only CCNs were included in the study, not registered nurses. The staff of other ICUs may include registered nurses.

Conclusion

Even though there are clear international guidelines for managing pain, sedation, delirium, immobility, and sleep in critically ill patients, the present study showed perceived variations in sedation practice between ICUs in Norway. The findings indicated that CCNs used sedatives to compensate critical care patients lack of sleep during the night. Important factors were identified as affecting the CCNs’ perception of whether noise and light were a contributing factor for sleep interruption. The most important factors for noise in the ICU were reported to be alarms from technical equipment and nurses talking together. The most important factor for light in the ICU at night was light from small lamps.

Further studies should involve the implementation of analgosedation, with a specific focus on management of sleep using the analgosedation approach. In addition, studies evaluating which actions nurses perform to reduce noise and light should be performed. To attain the goal of minimising the strain experienced by an ICU patient during a stay in intensive care, this paper recommends that ICUs carry out quality improvement, including a clinical audit, to explore the practice of sleep and sedation in critical care patients.

Acknowledgement

The authors would like to thank all the CCNs for their participation, and Idunn Brekke at Oslo Metropolitan University for excellent supervision during the period of the study.