Psychoacoustic analysis of noise and the application of earplugs in an ICU: A randomised controlled clinical trial.

BACKGROUND: Patients and medical staff are exposed to high noise levels in ICUs, which may have a negative impact on their health. Due to the diversity of noise sources present, including the operating noise of medical devices, staff conversations and the unwrapping of disposables, noise profiles are varied. Psychoacoustics deals with the analysis of sound, focusing on its effects on physiological perception and stress. OBJECTIVES: The aim of our study was to examine and to classify noise and its psychoacoustic properties in different locations in our ICU at different times. The impact of noise on subjective parameters and stress-related physiological data was also assessed with and without interventional methods. DESIGN: A randomised, controlled, single-blinded clinical trial. SETTING: University Hospital, from November 2010 to May 2011. PATIENTS: One hundred and forty-four patients in the ICU. INTERVENTIONS: In the first part, multidisciplinary psychoacoustic measurement was performed on the patients in our ICU. In the subsequent clinical trial, patients were equipped with effective earplugs, less effective earplugs and no earplugs. Thereafter, active noise cancellation headphones with or without sound masking were employed on a third patient population. MAIN OUTCOME MEASURES: Cortisol and α-amylase in saliva, skin conductance measures, vital signs, psychoacoustic analyses and two standardised questionnaires [State-Trait Anxiety Inventory (STAI) and Hospital Anxiety and Depression Scale (HADS)] were assessed. RESULTS: In the first part, the mean ±â€Šstandard deviation (SD) subjective loudness was 9.2 ±â€Š4.0 sone. Although absolute sound pressure level and loudness were lower during the night, the number of loud events increased significantly. Skin conductance in the earplug groups was significantly reduced in comparison to that in the control population but not the active noise reduction groups. Nevertheless, noise reduction was found to be comfortable for most patients. CONCLUSION: Noise in the ICU is of high clinical relevance. Diverse noise reduction methods, such as earplugs and active noise cancellation, are available. The avoidance of unnecessary noise, however, should be the primary focus. TRIAL REGISTRATION: German Clinical Trials Register (DRKS00000534).

Acute pain therapy in postanesthesia care unit directed by skin conductance: a randomized controlled trial.

BACKGROUND: After surgery, effective and well-directed acute pain therapy is a necessary and integral part of the overall treatment plan. Generally, the assessment of pain intensity depends on a patient's self-evaluation using scoring systems such as numeric rating scales (NRS, 0 to 10). Recently, a "Pain Monitor" was commercially provided which is based on measurements of fluctuations of skin conductance (NFSC). In this randomized, controlled, single-blind trial, possible benefits of this certain device were studied. METHODS: Postoperative patients (n = 44) were randomly assigned to a test or a control group during their stay in the postanesthesia care unit (PACU). All patients were treated and monitored according to internal hospital standards. Whereas all patients systematically evaluated their pain each 15 min, test group patients were additionally addressed when NFSC exceeded a predefined level. In cases of NRS≥5 during a routine elevation or in between, pain relief was achieved by standard procedures irrespective of group allocation. RESULTS: During their stay in PACU, both test and control groups experienced a significant decrease in NRS as a consequence of pain therapy. No significant differences in mean NRS or in NFSC values were found between the test and control groups. No correlation was observed between NRS and NFSC. CONCLUSION: Postoperative patients experience diverse stressors, such as anxiety, disorientation, shivering, sickness and pain. Although the application of continuous pain monitoring would be meaningful in this clinical setting, the tested device failed to distinguish pain from other stressors in postoperative adult patients. TRIAL REGISTRATION: German Clinical Trials Register DRKS00000755.