Effects of Family-Proxy-Selected Natural Sound Therapy Versus Standardized Natural Sound and Noise Reduction on Procedural Pain During Endotracheal Suctioning in Non-Communicative Mechanically Ventilated Adults: A Four-Arm Randomized Controlled Trial

**Background and Rationale**

Endotracheal suctioning is frequently performed in mechanically ventilated patients to maintain airway patency and remove accumulated respiratory secretions. Despite its clinical importance, suctioning can be associated with pain and physiological stress. Patients who are unable to communicate verbally may be particularly vulnerable because they cannot directly describe the intensity or nature of their pain.

Pain assessment in non-communicative critically ill patients therefore requires systematic observation using an appropriate validated behavioral pain assessment instrument. In addition to routine clinical pain management, non-pharmacological interventions may provide supportive strategies for reducing procedural pain.

Natural sound therapy is a potential non-pharmacological intervention that may help reduce distress during painful or uncomfortable procedures. However, the effect of natural sounds may depend on the type of sound used and its relevance to the individual patient. Family members may provide useful information about a patient's familiar sounds and preferences when the patient cannot communicate these preferences directly. Family-proxy-selected natural sounds may therefore offer a personalized approach, whereas standardized natural sounds provide a more uniform intervention that can be delivered consistently across participants.

Environmental noise reduction represents a separate approach that focuses on minimizing unnecessary sound exposure rather than introducing therapeutic sounds. Comparing these strategies may help clarify their respective effects on procedural pain during endotracheal suctioning.

**Study Objective**

The primary objective is to compare procedural pain during endotracheal suctioning among non-communicative, mechanically ventilated adults assigned to family-proxy-selected natural sound therapy, standardized natural sound therapy, noise reduction, or the protocol-defined control condition.

The study will evaluate whether these approaches differ in their effects on observed procedural pain. The results may contribute to evidence-based nursing care for critically ill patients who cannot communicate verbally.

**Study Design**

This study is a four-arm randomized controlled trial involving non-communicative adults receiving mechanical ventilation who require endotracheal suctioning. Eligible participants will be randomly allocated to one of four groups according to the study's randomization procedure.

The four groups will be defined as follows:

1. **Family-Proxy-Selected Natural Sound Therapy Group:** Participants will receive natural sound therapy using sounds selected by a family member or designated proxy based on the proxy's knowledge of the patient's preferences or familiarity with particular sounds.
2. **Standardized Natural Sound Therapy Group:** Participants will receive a predefined natural sound intervention selected by the research team according to a standardized protocol.
3. **Noise Reduction Group:** Participants will receive the protocol-defined environmental noise reduction intervention during the relevant procedural period. The intervention will focus on reducing unnecessary environmental sound exposure.
4. **Control Group:** Participants will receive the standard care specified in the study protocol without the additional intervention assigned to the other groups.

The precise intervention procedures, timing, duration, sound delivery method, and control condition will follow the finalized study protocol.

**Study Population**

The study population will consist of adults receiving invasive mechanical ventilation who are unable to communicate their pain verbally and require endotracheal suctioning. Participants will be screened against prespecified eligibility criteria before enrollment.

**Outcome Assessment**

The primary outcome will be procedural pain associated with endotracheal suctioning. Pain will be assessed using the behavioral pain assessment instrument specified in the protocol and appropriate for non-communicative critically ill adults. Assessments will be conducted at prespecified time points in relation to the suctioning procedure.

The study will compare pain scores across the four randomized groups according to the prespecified statistical analysis plan. Any secondary outcomes, additional physiological measurements, assessment time points, and safety assessments will be defined in the finalized protocol and registered in the appropriate outcome fields.

**Potential Significance**

This study will provide a comparative evaluation of three non-pharmacological approaches to procedural pain management in mechanically ventilated adults who cannot communicate verbally. By examining personalized natural sound therapy, standardized natural sound therapy, and environmental noise reduction within a randomized design, the study may help identify approaches that can be considered as supportive components of nursing care during endotracheal suctioning.

These interventions are intended to be evaluated within the context of appropriate routine clinical care and should not replace indicated analgesia, established pain assessment, or other necessary clinical management.