Introduction
Humans use their senses to evaluate situations in which they find themselves. From birth and beyond, optimal survival requires accurate interpretation of senses of taste, touch, smell, sight, and sound. Hearing ranks as the most important sense after sight. Critically ill adults are vulnerable when admitted to the intensive care unit (ICU) because patients are bombarded with unfamiliar sounds, bright lights, and interruptions, creating a potentially hostile environment.
Imagine waking up to the sounds of a bedside computer keeping track of blood pressure, heart rate, and respiratory rate or oxygen saturation; mechanical ventilation; continuous lateral rotation; feeding pumps; external pneumatic compressions devices; medication pumps and a continuous Yankauer suction setup tucked under a pillow. Then consider audible alarms from any 1 or 2 of those technical devices. Now interpret those sounds accurately. And by the way, the 10-member multidisciplinary team is rounding in the hallway just outside your room. Several loud voices are heard discussing medication profiles and treatment plans. Interpret those sounds as well.
Noisy ICUs and bright lights are undesirable because evidence shows that such stimuli can cause both psychological and physiologic harm in an environment otherwise focused on recovery and healing. Negative psychological states such as agitation, confusion, and delirium follow the stimuli of sleepinterrupting noises or bright lights. The incidence of ICU-acquired delirium has been reported to be as low as 20% and as high as 80%. A continuously noisy atmosphere as just described can cause physiologic harm with cardiovascular stimulation and suppression of immune response to infection. ICU patients already in septic shock or recovering from massive or acute myocardial infarction do not need increased demands on cardiovascular or immune systems. Undesirable consequences follow sensory overload, especially in critically ill adults.
Instead of getting quieter, ICUs may in fact be getting noisier over time. Experts report that sound levels or decibels (dB) all exceed recommended levels for hospital care. Interest in reducing noise in ICUs is growing. Several teams are studying ways to reduce or eliminate unwanted or unnecessary noise to improve patients' outcomes. Thus, the PICO (patient/problem, intervention, comparison, outcomes) question that this review addresses is, What effect do the interventions of earplugs and eye masks have on sleep and delirium outcomes in critically ill adults?