Background & Purpose: Family caregivers of critically ill patients are at high risk of developing adverse psychological outcomes such as anxiety, depression, and post-traumatic stress disorder (PTSD). Family caregivers of mechanically ventilated (MV) patients in the ICU also experience difficulty communicating with MV patients. However, little is known about patient-family communication in the ICU and the associated emotional distress. The goal of this pilot study was to assess the feasibility, acceptability, and preliminary efficacy of a newly developed evidence-based electronic communication application, VidaTalk TM among ICU family caregivers and explore family member communication experience, perceptions of the VidaTalk TM , and emotional reactions to the communication. Methods: This study used a mixed-methods design with repeated measures nested within an existing randomized controlled trial (RCT). The intervention group received the VidaTalk TM application whereas the attention control (AC) group received a standard electronic tablet format during the patient's MV treatment in the ICU. Participants completed Family Visitation Logs during the study period to track their ICU visits and tablet usage during each visit. Family caregiver perceived communication difficulty (Family Communication Scale [FCS]), anxiety (Hospital Anxiety and Depression Scale [HADS] -anxiety subscale), and depressive symptoms (HADS-depression) were measured at baseline, at extubation/ICU discharge, and 1-, 3-, and 6months post-ICU discharge. PTSD-related symptoms (Impact of Event Scale-revised [IES-R])were measured at 1-, 3-, and 6-months post-ICU discharge. Semi-structured qualitative interviews were performed with family caregivers in the VidaTalk TM group. Feasibility was determined by recruitment rate, retention rates, and number of ICU visits (>/= 3 days per week).iii Acceptability was measured by reported use of VidaTalk TM and qualitative evaluation of the VidaTalk TM . t-tests were used for group comparisons for anxiety and depression, and Mann-Whitney U tests were used for PTSD-related symptom comparisons.Results: Thirty four family caregivers of MV ICU patients participated in the study. Analyses indicated that the VidaTalk TM was feasible and acceptable for family caregivers during the ICU stay. The VidaTalk TM and AC groups were not significantly different regarding anxiety, depression, and PTSD-related symptoms across all time points. Although no statistically significant difference was found, the VidaTalk TM application was associated with medium effect size in anxiety symptom reduction (d = 0.42) at 1-month. The VidaTalk TM group had lower PTSD-related symptoms with a medium-to-large effect size (ɳ2=0.09) at 3-months. The qualitative data indicated that, overall, the families had a positive experience with the VidaTalk TM , found it helpful to communicate with MV patients, and experienced both positive and negative emotions while communicating with the patients. Family's perceptions of the VidaTalk TM clustered into seve...