Effect of nature-based sounds’ intervention on agitation, anxiety, and stress in patients under mechanical ventilator support: A randomised controlled trial

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Abstract

Background

Few studies have been conducted to investigate the effect of nature-based sounds (N-BS) on agitation, anxiety level and physiological signs of stress in patients under mechanical ventilator support. Non-pharmacological nursing interventions such as N-BS can be less expensive and efficient ways to alleviate anxiety and adverse effects of sedative medications in patients under mechanical ventilator support.

Objectives

This study was conducted to identify the effect of the nature-based sounds’ intervention on agitation, anxiety level and physiological stress responses in patients under mechanical ventilation support.

Methods

A randomized placebo-controlled trial design was used to conduct this study. A total of 60 patients aged 18–65 years under mechanical ventilation support in an intensive care unit were randomly assigned to the control and experimental groups. The patients in the intervention group received 90 min of N-BS. Pleasant nature sounds were played to the patients using media players and headphones. Patients’ physiological signs were taken immediately before the intervention and at the 30th, 60th, 90th minutes and 30 min after the procedure had finished. The physiological signs of stress assessed were heart rate, respiratory rate, and blood pressure. Data were collected over eight months from Oct 2011 to June 2012. Anxiety levels and agitation were assessed using the Faces Anxiety Scale and Richmond Agitation Sedation Scale, respectively.

Results

The experimental group had significantly lower systolic blood pressure, diastolic blood pressure, anxiety and agitation levels than the control group. These reductions increased progressively in the 30th, 60th, 90th minutes, and 30 min after the procedure had finished indicating a cumulative dose effect.

Conclusions

N-BS can provide an effective method of decreasing potentially harmful physiological responses arising from anxiety in mechanically ventilated patients. Nurses can incorporate N-BS intervention as a non-pharmacologic intervention into the daily care of patients under mechanical ventilation support in order to reduce their stress and anxiety.

Introduction

Mechanical ventilation (MV) is a common, lifesaving and frequently employed treatment modality for a variety of medical diagnoses in intensive care units (ICU) (Besel, 2006). While this intervention itself is a life saving treatment, patients who are mechanically ventilated often face a variety of distressing situations including anxiety and agitation due to emotional distress, fear of pain or dying, fear raised from family members’ previous experiences of those who have died in similar situations, discomfort, thirst, immobility, dyspnoea, confusion, and inability to relax (Dijkstra et al., 2010), pain, lack of sleep, tenseness, lack of control and loneliness, which are typically common stress and anxious reactions even when patients are sedated (Yagan et al., 2000, Rotondi et al., 2002, Thomas, 2003).

Patients undergoing MV require endotracheal intubation and often have either intermittent or sustained periods of agitation because of the endotracheal tube itself. Intubated patients who are relatively alert mostly become frustrated by their inability to communicate verbally and then fall into a cycle of continued agitation. Finally, the ICU environment, with its high noise levels, lights, and continual other stimuli can significantly contribute to increasing distress and agitation (Heiderscheit et al., 2011, Khalaila et al., 2011).

Having a dependency on MV to breathe can result in sleep disturbances, increased myocardial oxygen consumption and increased sympathetic output (Tracy and Chlan, 2011). Poorly managed stress can result in the patient's inability to adjust to the disease and the use of medical assistance or anti-anxiety agents (Wong et al., 2001). Thus, MV may be a distressing experience for the patient, and may result in an increase in anxiety and reduced comfort even when the patient is sedated (Besel, 2006).

Nurses in the ICU frequently administer sedative medication to ventilated patients to counteract the negative effects of treatment. However, sedative agents have a number of undesirable side effects, which may result in complications such as nausea and vomiting, decreased gut motility, urinary retention, mental status instability, respiratory depression, pruritus, venous stasis, hypotension, soft tissue damage, respiratory and extremity muscle weakness or atrophia, increased risk of infection, central nervous system changes and even death, and delayed weaning from MV (Chlan, 2002). These, in turn, prolong the length of dependency on the ventilator (Lee et al., 2005, Lindgren and Ames, 2005), increase length of stay in the ICU, increase the need for medication, and costs of hospital care (Seneff et al., 2000, Arroliga et al., 2005).

Drugs may be prescribed to preserve patient safety during periods of severe agitation and anxiety. However, use of complementary therapies in conjunction with sedative agents may potentiate the effects of both types of therapies and decrease the amount of sedative drugs needed to get the same outcome. Complementary therapies, if used on a routine basis, can help reduce anxiety (Pun and Dunn, 2007). Therefore, sedative drugs do not have to be the first choice in attempts to mitigate patients’ distress associated with MV support (Chlan, 2002).

There is a need for additional research examining alternative non-pharmacological interventions for patients requiring MV. Non-pharmacological approaches consist of a variety of environmental adjustments that are frequently underutilized (Summer, 2002). Although music therapy has been shown to be an effective intervention in the care of patients under MV, not all patients welcome this intervention. Nurses caring for patients under MV support must have several non-pharmacological adjuncts, which can be implemented in order to provide a humanistic caring environment in which healing can occur (Chlan, 2002). In this respect, sound therapy can act as a non-pharmacological nursing intervention to allay the signs of anxiety in such patients. Sound therapy has been used to reduce anxiety and distress and improve physiological functioning in medical patients; however its effect on patients under mechanical ventilation support needs to be investigated.

Ulrich (1984) demonstrated that patients whose windows faced a park recovered faster compared to patients whose windows faced a brick wall. Since then, several studies have demonstrated restorative effects of natural environments in comparison with urban environments. These effects include increased well-being and decreased physiological stress responses (Grinde and Patil, 2009, Maller et al., 2006).

Ulrich suggested that natural environments have restorative effects by inducing positive emotional states, decreased physiological activity, and sustained attention (Ulrich, 1984). This is concurrent with Kaplan and Kaplan's theory (1995) that a natural environment facilitates recovery of directed attention capacity and thereby reduces mental fatigue (Kaplan, 1995). It has also been found that positive emotion improves physiological recovery after stress (Fredrickson et al., 2000). Soundscape research has shown that natural sounds are typically perceived to be pleasant (Lavandier and Defréville, 2006, Nilsson and Berglund, 2006).

Nature sounds have a positive emotional effect on all people (Maller et al., 2006), and are used in studies as they have the most relaxing effect in comparison to other interventions (Lavandier and Defréville, 2006, Nilsson and Berglund, 2006). Nature sounds are limited only by geographical boundaries and have the capacity to appeal to all cultures. Nature-based sounds (NB-S) in the pre-operative area can be considered culturally neutral (Cullum, 1997).

Investigators at Johns Hopkins Medical Centre (2003) have strong evidence that distracting patients during and after bronchoscopy with a colourful mural of a meadow and the gurgle of a babbling brook significantly enhances efforts to reduce pain (Anon., 2003). The Hopkins group tested the natural sights and sounds on 41 men and women during their 25-min bronchoscopies and three-hour recovery periods. They listened to nature sounds through headphones and a tape player. Thirty-nine similar patients underwent the procedures without distraction therapy, but with comparable levels of care and pain control. Both groups completed questionnaires rating their pain on a five-point scale, along with their anxiety, perceptions of privacy, difficulty in breathing, willingness to have the procedure done again and safety. Patients who listened to the nature sounds and looked at the mural during bronchoscopy were 43% more likely to report pain control as very good or excellent, even after controlling for such factors as pain medication, health, race and education (Anon., 2003).

No studies have focused on the effect of NB-S on physiological stress responses, agitation and anxiety level in patients receiving MV support. This study was conducted to identify the effect of nature-based sounds’ intervention on agitation, anxiety level and physiological stress responses in patients under mechanical ventilation support.

Section snippets

Study design

A randomized placebo-controlled trial was used to conduct this study (Fig. 1) from Oct 2011 to June 2012. To determine the sample size, a pilot study was conducted with five patients. The least amount of difference in each endpoint was related to agitation 30 and 60 min after the intervention in the experiment group (0.0 ± 0.707) and in the control group (0.6 ± 0.548). Using the statistical parameters of α = 0.5 and β = 0.5, the sample size was determined to be 30 patients in both the intervention and

Demographical and baseline characteristics of the patients

In this study, 60 patients were randomly assigned to the control (n = 30) and intervention (n = 30) groups. In the control group, 20 patients (66.7%) were male and 10 patients (33.3%) female. In the intervention group, 14 patients (46.7%) were male and 16 patients (53.3%) female (p = 0.118). The mean ± SD age of the patients were 46.60 ± 16.76 and 41.23 ± 15.31 in the control and intervention groups, respectively (p = 0.201). The rate of illiteracy was 23.3% (7 patients) in the control group and 30.0% (9

Discussion

This study was conducted to determine the effect of the N-BS intervention on the physiological stress responses, anxiety level, and agitation of patients under mechanical ventilation support. Specifically, the anxiety responses of the patients were measured using their physiological parameters when provided with N-BS in the intervention group, and no sound for the control group.

In recent years, use of the N-BS intervention as a complementary therapy has increased and this, to some extent, may

Conclusion

This study provides evidence for the use of nature-sound as an anxiolytic intervention. The benefits of preventing physiological reactions to anxiety were demonstrated, in patients who were under mechanical ventilator support. Therefore, nature-sound can provide an easy, simple, safe and effective method of reducing potentially harmful physiological responses arising from anxiety.

This study showed that changing surrounding environmental sounds decreases environmental stimulation, which results

Acknowledgments

This research was supported financially by the Shahed University. The researchers would like to thank the patients for their participation in this study.

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